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Sample records for retinal vessel diameters

  1. Heritability of retinal vessel diameters and blood pressure

    DEFF Research Database (Denmark)

    Taarnhøj, Nina C B B; Larsen, Michael; Sander, Birgit

    2006-01-01

    PURPOSE: To assess the relative influence of genetic and environmental effects on retinal vessel diameters and blood pressure in healthy adults, as well as the possible genetic connection between these two characteristics. METHODS: In 55 monozygotic and 50 dizygotic same-sex healthy twin pairs......%-80%) for CRAE, 83% (95% CI: 73%-89%) for CRVE, and 61% (95% CI: 44%-73%) for mean arterial blood pressure (MABP). Retinal artery diameter decreased with increasing age and increasing arterial blood pressure. Mean vessel diameters in the population were 165.8 +/- 14.9 microm for CRAE, 246.2 +/- 17.7 microm...... for CRVE, and 0.67 +/- 0.05 microm for AVR. No significant influence on artery or vein diameters was found for gender, smoking, body mass index (BMI), total cholesterol, fasting blood glucose, or 2-hour oral glucose tolerance test values. CONCLUSIONS: In healthy young adults with normal blood pressure...

  2. Novel Computerized Method for Measurement of Retinal Vessel Diameters

    Directory of Open Access Journals (Sweden)

    Hichem Guedri

    2017-03-01

    Full Text Available Several clinical studies reveal the relationship between alterations in the topologies of the human retinal blood vessel, the outcrop and the disease evolution, such as diabetic retinopathy, hypertensive retinopathy, and macular degeneration. Indeed, the detection of these vascular changes always has gaps. In addition, the manual steps are slow, which may be subjected to a bias of the perceiver. However, we can overcome these troubles using computer algorithms that are quicker and more accurate. This paper presents and investigates a novel method for measuring the blood vessel diameter in the retinal image. The proposed method is based on a thresholding segmentation and thinning step, followed by the characteristic point determination step by the Douglas-Peucker algorithm. Thereafter, it uses the active contours to detect vessel contour. Finally, Heron’s Formula is applied to assure the calculation of vessel diameter. The obtained results for six sample images showed that the proposed method generated less errors compared to other techniques, which confirms the high performance of the proposed method.

  3. Does Physical Fitness Buffer the Relationship between Psychosocial Stress, Retinal Vessel Diameters, and Blood Pressure among Primary Schoolchildren?

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    Endes, Katharina; Herrmann, Christian; Colledge, Flora; Brand, Serge; Donath, Lars; Faude, Oliver; Pühse, Uwe; Hanssen, Henner; Zahner, Lukas

    2016-01-01

    Background. Strong evidence exists showing that psychosocial stress plays an important part in the development of cardiovascular diseases. Because physical inactivity is associated with less favourable retinal vessel diameter and blood pressure profiles, this study explores whether physical fitness is able to buffer the negative effects of psychosocial stress on retinal vessel diameters and blood pressure in young children. Methods. 325 primary schoolchildren (51% girls, Mage = 7.28 years) took part in this cross-sectional research project. Retinal arteriolar diameters, retinal venular diameters, arteriolar to venular ratio, and systolic and diastolic blood pressure were assessed in all children. Interactions terms between physical fitness (performance in the 20 m shuttle run test) and four indicators of psychosocial stress (parental reports of critical life events, family, peer and school stress) were tested in a series of hierarchical regression analyses. Results. Critical life events and family, peer, and school-related stress were only weakly associated with retinal vessel diameters and blood pressure. No support was found for a stress-buffering effect of physical fitness. Conclusion. More research is needed with different age groups to find out if and from what age physical fitness can protect against arteriolar vessel narrowing and the occurrence of other cardiovascular disease risk factors. PMID:27795958

  4. Visual function and retinal vessel diameters during hyperthermia in man

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    Jensen, Bettina Hagström; Bram, Thue; Kappelgaard, Per

    2017-01-01

    .01), a 10.6-mmHg mean reduction in diastolic blood pressure (p vein...... laser ophthalmoscopy was used to measure retinal trunk vessel diameters. Assessment was made at baseline, during hyperthermia and after cooling. RESULTS: The induction of a mean increase in core body temperature of 1.02°C was associated with a 7.15-mmHg mean reduction in systolic blood pressure (p

  5. Quantitative measurement of changes in retinal vessel diameter in ocular fundus images

    DEFF Research Database (Denmark)

    Pedersen, Lars; Grunkin, Michael; Ersbøll, Bjarne Kjær

    2000-01-01

    The change in diameter of retinal vessels as a function of increasing distance to the optic disc is believed to be indicative of the risk level of various vascular diseases such as generalised arteriosclerosis and Diabetes Mellitus. In particular, focal arteriolar narrowing (FAN) is considered re...

  6. Relationship between retinal vessel diameters and retinopathy in the Inter99 Eye Study

    DEFF Research Database (Denmark)

    Drobnjak, Dragana; Munch, Inger Christine; Glümer, Charlotte

    2017-01-01

    PURPOSE: To examine the association between retinal vessel diameters and retinopathy in participants with and without type 2 diabetes in a Danish population-based cohort. METHODS: The study included 878 persons aged 30 to 60 years from the Inter99 Eye Study. Retinopathy was defined as a presence...... was 6.3 µm (CI 95%: 1.0 to 11.6, p = 0.020) wider and CRVE was 7.9 µm (CI 95%: 0.7 to 15.2, p = 0.030) wider in those with retinopathy compared to those without retinopathy, after adjusting for age, gender, HbA1c, blood pressure, smoking, serum total and HDL cholesterol. In all participants, CRAE.......001), and decreased with higher HDL cholesterol (p gender was associated with wider CRVE (p = 0.029). CONCLUSIONS: Wider retinal vessel diameters were associated with the presence of retinopathy in participants with diabetes, but not in participants without diabetes...

  7. Retinal hemodynamic oxygen reactivity assessed by perfusion velocity, blood oximetry and vessel diameter measurements

    DEFF Research Database (Denmark)

    Klefter, Oliver Niels; Lauritsen, Anne Øberg; Larsen, Michael

    2015-01-01

    PURPOSE: To test the oxygen reactivity of a fundus photographic method of measuring macular perfusion velocity and to integrate macular perfusion velocities with measurements of retinal vessel diameters and blood oxygen saturation. METHODS: Sixteen eyes in 16 healthy volunteers were studied at two...... is a valid method for assessing macular perfusion. Results were consistent with previous observations of hyperoxic blood flow reduction using blue field entoptic and laser Doppler velocimetry. Retinal perfusion seemed to be regulated around individual set points according to blood glucose levels. Multimodal...

  8. Automated detection and classification of major retinal vessels for determination of diameter ratio of arteries and veins

    Science.gov (United States)

    Muramatsu, Chisako; Hatanaka, Yuji; Iwase, Tatsuhiko; Hara, Takeshi; Fujita, Hiroshi

    2010-03-01

    Abnormalities of retinal vasculatures can indicate health conditions in the body, such as the high blood pressure and diabetes. Providing automatically determined width ratio of arteries and veins (A/V ratio) on retinal fundus images may help physicians in the diagnosis of hypertensive retinopathy, which may cause blindness. The purpose of this study was to detect major retinal vessels and classify them into arteries and veins for the determination of A/V ratio. Images used in this study were obtained from DRIVE database, which consists of 20 cases each for training and testing vessel detection algorithms. Starting with the reference standard of vasculature segmentation provided in the database, major arteries and veins each in the upper and lower temporal regions were manually selected for establishing the gold standard. We applied the black top-hat transformation and double-ring filter to detect retinal blood vessels. From the extracted vessels, large vessels extending from the optic disc to temporal regions were selected as target vessels for calculation of A/V ratio. Image features were extracted from the vessel segments from quarter-disc to one disc diameter from the edge of optic discs. The target segments in the training cases were classified into arteries and veins by using the linear discriminant analysis, and the selected parameters were applied to those in the test cases. Out of 40 pairs, 30 pairs (75%) of arteries and veins in the 20 test cases were correctly classified. The result can be used for the automated calculation of A/V ratio.

  9. Retinal vessel diameters decrease with macular ganglion cell layer thickness in autosomal dominant optic atrophy and in healthy subjects

    DEFF Research Database (Denmark)

    Rönnbäck, Cecilia; Grønskov, Karen; Larsen, Michael

    2014-01-01

    diameters (central retinal artery equivalent, CRAE, and central retinal vein equivalent, CRVE). Statistical analysis was corrected for age, gender, spherical equivalent refraction, axial length and mean arterial blood pressure (MABP) in a mixed model analysis. RESULTS: Retinal arteries and veins were...... ganglion cell-inner plexiform layer (GC-IPL) thickness (p = 0.0017 and p = 0.0057, respectively). CONCLUSION: Narrow retinal arteries and veins were associated not only with the severity of ADOA but with ganglion cell volume in patients with ADOA and in healthy subjects. This suggests that narrow vessels...

  10. Retinal vessel diameter and estimated cerebrospinal fluid pressure in arterial hypertension: the Beijing Eye Study.

    Science.gov (United States)

    Jonas, Jost B; Wang, Ningli; Wang, Shuang; Wang, Ya Xing; You, Qi Sheng; Yang, Diya; Wei, Wen Bin; Xu, Liang

    2014-09-01

    Hypertensive retinal microvascular abnormalities include an increased retinal vein-to-artery diameter ratio. Because central retinal vein pressure depends on cerebrospinal fluid pressure (CSFP), we examined whether the retinal vein-to-artery diameter ratio and other retinal hypertensive signs are associated with CSFP. Participants of the population-based Beijing Eye Study (n = 1,574 subjects) underwent measurement of the temporal inferior and superior retinal artery and vein diameter. CSFP was calculated as 0.44 × body mass index (kg/m(2)) + 0.16 × diastolic blood pressure (mm Hg) - 0.18 × age (years) - 1.91. Larger retinal vein diameters and higher vein-to-artery diameter ratios were significantly associated with higher estimated CSFP (P = 0.001) in multivariable analysis. In contrast, temporal inferior retinal arterial diameter was marginally associated (P = 0.03) with estimated CSFP, and temporal superior artery diameter was not significantly associated (P = 0.10) with estimated CSFP; other microvascular abnormalities, such as arteriovenous crossing signs, were also not significantly associated with estimated CSFP. In a reverse manner, higher estimated CSFP as a dependent variable in the multivariable analysis was associated with wider retinal veins and higher vein-to-artery diameter ratio. In the same model, estimated CSFP was not significantly correlated with retinal artery diameters or other retinal microvascular abnormalities. Correspondingly, arterial hypertension was associated with retinal microvascular abnormalities such as arteriovenous crossing signs (P = 0.003), thinner temporal retinal arteries (P arterial hypertension, an increased retinal vein-to-artery diameter ratio depends on elevated CSFP, which is correlated with blood pressure. © American Journal of Hypertension, Ltd 2014. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. Dependence of diameters and oxygen saturation of retinal vessels on visual field damage and age in primary open-angle glaucoma.

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    Ramm, Lisa; Jentsch, Susanne; Peters, Sven; Sauer, Lydia; Augsten, Regine; Hammer, Martin

    2016-05-01

    To investigate the interrelationship between the oxygen supply of the retina and its regulation with the severity of primary open-angle glaucoma (POAG). Central retinal artery (CRAE) and vein (CRVE) diameters and oxygen saturation of peripapillary retinal vessels in 41 patients suffering from POAG (64.1 ± 12.9 years) and 40 healthy volunteers (63.6 ± 14.1 years) were measured using the retinal vessel analyzer. All measures were taken before and during flicker light stimulation. The mean retinal nerve fiber layer thickness (RNFLT) was determined by OCT and the visual field mean defect (MD) was identified using perimetry. In glaucoma patients, CRAE (r = -0.48 p = 0.002) and CRVE (r = -0.394 p = 0.014) at baseline were inversely related to MD, while arterial and venous oxygen saturation showed no significant dependence on the severity of the damage. However, the flicker light-induced change in arterio-venous difference in oxygen saturation was correlated with the MD (r = 0.358 p = 0.027). The diameters of arteries and veins at baseline decreased with reduction of the mean RNFLT (arteries: r = 0.718 p field loss, may be explained by a reduction of the retinal metabolic demand with progressive loss of neuronal tissue in glaucoma. © 2015 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  12. Retinal Oximetry and Vessel Diameter Measurements With a Commercially Available Scanning Laser Ophthalmoscope in Diabetic Retinopathy.

    Science.gov (United States)

    Blair, Norman P; Wanek, Justin; Felder, Anthony E; Joslin, Charlotte E; Kresovich, Jacob K; Lim, Jennifer I; Chau, Felix Y; Leiderman, Yannek; Shahidi, Mahnaz

    2017-10-01

    To test the hypothesis that retinal vascular diameter and hemoglobin oxygen saturation alterations, according to stages of diabetic retinopathy (DR), are discernible with a commercially available scanning laser ophthalmoscope (SLO). One hundred eighty-one subjects with no diabetes (No DM), diabetes with no DR (No DR), nonproliferative DR (NPDR), or proliferative DR (PDR, all had photocoagulation) underwent imaging with an SLO with dual lasers (532 nm and 633 nm). Customized image analysis software determined the diameters of retinal arteries and veins (DA and DV) and central retinal artery and vein equivalents (CRAE and CRVE). Oxygen saturations of hemoglobin in arteries and veins (SO2A and SO2V) were estimated from optical densities of vessels on images at the two wavelengths. Statistical models were generated by adjusting for effects of sex, race, age, eye, and fundus pigmentation. DA, CRAE, and CRVE were reduced in PDR compared to No DM (P ≤ 0.03). DV and CRVE were similar between No DM and No DR, but they were higher in NPDR than No DR (P ≤ 0.01). Effect of stage of disease on SO2A differed by race, being increased relative to No DM in NPDR and PDR in Hispanic participants only (P ≤ 0.02). Relative to No DM, SO2V was increased in NPDR and PDR (P ≤ 0.05). Alterations in retinal vascular diameters and SO2 by diabetic retinopathy stage can be detected with a widely available SLO, and covariates such as race can influence the results.

  13. Retinal vessel diameters in relation to hematocrit variation during acclimatization of highlanders to sea level altitude

    DEFF Research Database (Denmark)

    Kofoed, Peter Kristian; Sander, Birgit; Zubieta-Calleja, Gustavo

    2009-01-01

    PURPOSE: To examine variations in retinal vessel diameters during acclimatization of native highlanders to normobaric normoxia at sea level. METHODS: Fifteen healthy residents of the greater La Paz region in Bolivia (3600 m above sea level) were examined thrice over a 72-day period, after having...... traveled by airplane to Copenhagen, Denmark, near sea level. RESULTS: In the study subjects, hematocrit decreased from 49.6% (day 2) to 45.9% (P = 0.0066, day 23) and 41.7% (P ... diameters were indistinguishable from baseline after 72 days. No funduscopic signs of retinopathy were observed. Arterial blood pressure remained stable throughout the study. CONCLUSIONS: Although a 16% reduction in hematocrit occurred between days 2 and 72 after arrival at sea level, the only significant...

  14. Application of morphological bit planes in retinal blood vessel extraction.

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    Fraz, M M; Basit, A; Barman, S A

    2013-04-01

    The appearance of the retinal blood vessels is an important diagnostic indicator of various clinical disorders of the eye and the body. Retinal blood vessels have been shown to provide evidence in terms of change in diameter, branching angles, or tortuosity, as a result of ophthalmic disease. This paper reports the development for an automated method for segmentation of blood vessels in retinal images. A unique combination of methods for retinal blood vessel skeleton detection and multidirectional morphological bit plane slicing is presented to extract the blood vessels from the color retinal images. The skeleton of main vessels is extracted by the application of directional differential operators and then evaluation of combination of derivative signs and average derivative values. Mathematical morphology has been materialized as a proficient technique for quantifying the retinal vasculature in ocular fundus images. A multidirectional top-hat operator with rotating structuring elements is used to emphasize the vessels in a particular direction, and information is extracted using bit plane slicing. An iterative region growing method is applied to integrate the main skeleton and the images resulting from bit plane slicing of vessel direction-dependent morphological filters. The approach is tested on two publicly available databases DRIVE and STARE. Average accuracy achieved by the proposed method is 0.9423 for both the databases with significant values of sensitivity and specificity also; the algorithm outperforms the second human observer in terms of precision of segmented vessel tree.

  15. Probabilistic retinal vessel segmentation

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    Wu, Chang-Hua; Agam, Gady

    2007-03-01

    Optic fundus assessment is widely used for diagnosing vascular and non-vascular pathology. Inspection of the retinal vasculature may reveal hypertension, diabetes, arteriosclerosis, cardiovascular disease and stroke. Due to various imaging conditions retinal images may be degraded. Consequently, the enhancement of such images and vessels in them is an important task with direct clinical applications. We propose a novel technique for vessel enhancement in retinal images that is capable of enhancing vessel junctions in addition to linear vessel segments. This is an extension of vessel filters we have previously developed for vessel enhancement in thoracic CT scans. The proposed approach is based on probabilistic models which can discern vessels and junctions. Evaluation shows the proposed filter is better than several known techniques and is comparable to the state of the art when evaluated on a standard dataset. A ridge-based vessel tracking process is applied on the enhanced image to demonstrate the effectiveness of the enhancement filter.

  16. Automatic Vessel Segmentation on Retinal Images

    Institute of Scientific and Technical Information of China (English)

    Chun-Yuan Yu; Chia-Jen Chang; Yen-Ju Yao; Shyr-Shen Yu

    2014-01-01

    Several features of retinal vessels can be used to monitor the progression of diseases. Changes in vascular structures, for example, vessel caliber, branching angle, and tortuosity, are portents of many diseases such as diabetic retinopathy and arterial hyper-tension. This paper proposes an automatic retinal vessel segmentation method based on morphological closing and multi-scale line detection. First, an illumination correction is performed on the green band retinal image. Next, the morphological closing and subtraction processing are applied to obtain the crude retinal vessel image. Then, the multi-scale line detection is used to fine the vessel image. Finally, the binary vasculature is extracted by the Otsu algorithm. In this paper, for improving the drawbacks of multi-scale line detection, only the line detectors at 4 scales are used. The experimental results show that the accuracy is 0.939 for DRIVE (digital retinal images for vessel extraction) retinal database, which is much better than other methods.

  17. C - reactive protein and chitinase 3-like protein 1 as biomarkers of spatial redistribution of retinal blood vessels on digital retinal photography in patients with diabetic retinopathy

    Directory of Open Access Journals (Sweden)

    Sonja Predrag Cekic

    2014-08-01

    Full Text Available The aim of the study was to investegate the correlation between the levels of CRP and YKL-40 in blood samples with morphometric parameters of retinal blood vessels in patients with diabetic retinopathy.Blood laboratory examination of 90 patients included the measurement of glycemia, HbA1C, total cholesterol, LDL-C, HDL-C, triglycerides and CRP. Levels of YKL-40 were detected and measured in serum by ELISA (Micro VueYKL-40 EIA Kit, Quidel Corporation, San Diego, USA.Morphmetric analysis was performed with ImageJ software (http://rsbweb.nih.gov/ij/ for digital retinal photography. We measured the number, diameter of retinal blood vessels in five different parts concentric to the optic disc. Differences between the morphometric parameters and the blood test analysis results were evaluated using the Student’s t – test. One Way ANOVA was used to establish the significance of differences.CRP and YKL-40 levels were moderately higher in the group of patients with severe diabetic retinopathy. Levels of YKL-40 correlated positively with diameter and negatively with number of retinal blood vessels. The average number of the blood vessels per retinal zone was significantly higher in the group of patients with mild non-proliferative diabetic retinopathy than in the group with severe form in the optic disc and all five retinal zones. The average outer diameter of the evaluated retinal zones and optic disc vessels was significantly higher in the group with severe compared to the group with mild diabetic retinopathy.Morphological analysis of the retinal vessels on digital fundus photography and correlation with YKL-40 may be valuable for the follow-up of diabetic retinopathy.

  18. Fast retinal vessel detection and measurement using wavelets and edge location refinement.

    Directory of Open Access Journals (Sweden)

    Peter Bankhead

    Full Text Available The relationship between changes in retinal vessel morphology and the onset and progression of diseases such as diabetes, hypertension and retinopathy of prematurity (ROP has been the subject of several large scale clinical studies. However, the difficulty of quantifying changes in retinal vessels in a sufficiently fast, accurate and repeatable manner has restricted the application of the insights gleaned from these studies to clinical practice. This paper presents a novel algorithm for the efficient detection and measurement of retinal vessels, which is general enough that it can be applied to both low and high resolution fundus photographs and fluorescein angiograms upon the adjustment of only a few intuitive parameters. Firstly, we describe the simple vessel segmentation strategy, formulated in the language of wavelets, that is used for fast vessel detection. When validated using a publicly available database of retinal images, this segmentation achieves a true positive rate of 70.27%, false positive rate of 2.83%, and accuracy score of 0.9371. Vessel edges are then more precisely localised using image profiles computed perpendicularly across a spline fit of each detected vessel centreline, so that both local and global changes in vessel diameter can be readily quantified. Using a second image database, we show that the diameters output by our algorithm display good agreement with the manual measurements made by three independent observers. We conclude that the improved speed and generality offered by our algorithm are achieved without sacrificing accuracy. The algorithm is implemented in MATLAB along with a graphical user interface, and we have made the source code freely available.

  19. C-reactive protein and chitinase 3-like protein 1 as biomarkers of spatial redistribution of retinal blood vessels on digital retinal photography in patients with diabetic retinopathy.

    Science.gov (United States)

    Cekić, Sonja; Cvetković, Tatjana; Jovanović, Ivan; Jovanović, Predrag; Pesić, Milica; Stanković Babić, Gordana; Milenković, Svetislav; Risimić, Dijana

    2014-08-20

    The aim of the study was to investigate the correlation between the levels of C-reactive protein (CRP) and chitinase 3-like protein 1 (YKL-40) in blood samples with morpohometric parameters of retinal blood vessels in patients with diabetic retinopathy. Blood laboratory examination of 90 patients included the measurement of glycemia, HbA1C, total cholesterol, LDL-C, HDL-C, triglycerides and CRP. Levels of YKL-40 were detected and measured in serum by ELISA (Micro VueYKL-40 EIA Kit, Quidel Corporation, San Diego, USA). YKL-40 correlated positively with diameter and negatively with number of retinal blood vessels. The average number of the blood vessels per retinal zone was significantly higher in the group of patients with mild non-proliferative diabetic retinopathy than in the group with severe form in the optic disc and all five retinal zones. The average outer diameter of the evaluated retinal zones and optic disc vessels was significantly higher in the group with severe compared to the group with mild diabetic retinopathy. Morphological analysis of the retinal vessels on digital fundus photography and correlation with YKL-40 may be valuable for the follow-up of diabetic retinopathy.

  20. Carbonic anhydrase inhibition increases retinal oxygen tension and dilates retinal vessels

    DEFF Research Database (Denmark)

    Pedersen, Daniella Bach; Koch Jensen, Peter; la Cour, Morten

    2005-01-01

    Carbonic anhydrase inhibitors (CAIs) increase blood flow in the brain and probably also in the optic nerve and retina. Additionally they elevate the oxygen tension in the optic nerve in the pig. We propose that they also raise the oxygen tension in the retina. We studied the oxygen tension in the...... in the pig retina and optic nerve before and after dorzolamide injection. Also the retinal vessel diameters during carbonic anhydrase inhibition were studied....

  1. Retinal Vessels Segmentation Techniques and Algorithms: A Survey

    Directory of Open Access Journals (Sweden)

    Jasem Almotiri

    2018-01-01

    Full Text Available Retinal vessels identification and localization aim to separate the different retinal vasculature structure tissues, either wide or narrow ones, from the fundus image background and other retinal anatomical structures such as optic disc, macula, and abnormal lesions. Retinal vessels identification studies are attracting more and more attention in recent years due to non-invasive fundus imaging and the crucial information contained in vasculature structure which is helpful for the detection and diagnosis of a variety of retinal pathologies included but not limited to: Diabetic Retinopathy (DR, glaucoma, hypertension, and Age-related Macular Degeneration (AMD. With the development of almost two decades, the innovative approaches applying computer-aided techniques for segmenting retinal vessels are becoming more and more crucial and coming closer to routine clinical applications. The purpose of this paper is to provide a comprehensive overview for retinal vessels segmentation techniques. Firstly, a brief introduction to retinal fundus photography and imaging modalities of retinal images is given. Then, the preprocessing operations and the state of the art methods of retinal vessels identification are introduced. Moreover, the evaluation and validation of the results of retinal vessels segmentation are discussed. Finally, an objective assessment is presented and future developments and trends are addressed for retinal vessels identification techniques.

  2. Automated retinal vessel type classification in color fundus images

    Science.gov (United States)

    Yu, H.; Barriga, S.; Agurto, C.; Nemeth, S.; Bauman, W.; Soliz, P.

    2013-02-01

    Automated retinal vessel type classification is an essential first step toward machine-based quantitative measurement of various vessel topological parameters and identifying vessel abnormalities and alternations in cardiovascular disease risk analysis. This paper presents a new and accurate automatic artery and vein classification method developed for arteriolar-to-venular width ratio (AVR) and artery and vein tortuosity measurements in regions of interest (ROI) of 1.5 and 2.5 optic disc diameters from the disc center, respectively. This method includes illumination normalization, automatic optic disc detection and retinal vessel segmentation, feature extraction, and a partial least squares (PLS) classification. Normalized multi-color information, color variation, and multi-scale morphological features are extracted on each vessel segment. We trained the algorithm on a set of 51 color fundus images using manually marked arteries and veins. We tested the proposed method in a previously unseen test data set consisting of 42 images. We obtained an area under the ROC curve (AUC) of 93.7% in the ROI of AVR measurement and 91.5% of AUC in the ROI of tortuosity measurement. The proposed AV classification method has the potential to assist automatic cardiovascular disease early detection and risk analysis.

  3. An approach to localize the retinal blood vessels using bit planes and centerline detection.

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    Fraz, M M; Barman, S A; Remagnino, P; Hoppe, A; Basit, A; Uyyanonvara, B; Rudnicka, A R; Owen, C G

    2012-11-01

    The change in morphology, diameter, branching pattern or tortuosity of retinal blood vessels is an important indicator of various clinical disorders of the eye and the body. This paper reports an automated method for segmentation of blood vessels in retinal images. A unique combination of techniques for vessel centerlines detection and morphological bit plane slicing is presented to extract the blood vessel tree from the retinal images. The centerlines are extracted by using the first order derivative of a Gaussian filter in four orientations and then evaluation of derivative signs and average derivative values is performed. Mathematical morphology has emerged as a proficient technique for quantifying the blood vessels in the retina. The shape and orientation map of blood vessels is obtained by applying a multidirectional morphological top-hat operator with a linear structuring element followed by bit plane slicing of the vessel enhanced grayscale image. The centerlines are combined with these maps to obtain the segmented vessel tree. The methodology is tested on three publicly available databases DRIVE, STARE and MESSIDOR. The results demonstrate that the performance of the proposed algorithm is comparable with state of the art techniques in terms of accuracy, sensitivity and specificity. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  4. Retinal Vessel Oxygen Saturation during 100% Oxygen Breathing in Healthy Individuals.

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    Olof Birna Olafsdottir

    Full Text Available To detect how systemic hyperoxia affects oxygen saturation in retinal arterioles and venules in healthy individuals.Retinal vessel oxygen saturation was measured in 30 healthy individuals with a spectrophotometric retinal oximeter (Oxymap T1. Oximetry was performed during breathing of room air, 100% oxygen (10 minutes, 6L/min and then again room air (10 minutes recovery.Mean oxygen saturation rises modestly in retinal arterioles during 100% oxygen breathing (94.5%±3.8 vs. 92.0%±3.7% at baseline, p<0.0001 and dramatically in retinal venules (76.2%±8.0% vs. 51.3%±5.6%, p<0.0001. The arteriovenous difference decreased during 100% oxygen breathing (18.3%±9.0% vs. 40.7%±5.7%, p<0.0001. The mean diameter of arterioles decreased during 100% oxygen breathing compared to baseline (9.7±1.4 pixels vs. 10.3±1.3 pixels, p<0.0001 and the same applies to the mean venular diameter (11.4±1.2 pixels vs. 13.3±1.5 pixels, p<0.0001.Breathing 100% oxygen increases oxygen saturation in retinal arterioles and more so in venules and constricts them compared to baseline levels. The dramatic increase in oxygen saturation in venules reflects oxygen flow from the choroid and the unusual vascular anatomy and oxygen physiology of the eye.

  5. Unsupervised Retinal Vessel Segmentation Using Combined Filters.

    Directory of Open Access Journals (Sweden)

    Wendeson S Oliveira

    Full Text Available Image segmentation of retinal blood vessels is a process that can help to predict and diagnose cardiovascular related diseases, such as hypertension and diabetes, which are known to affect the retinal blood vessels' appearance. This work proposes an unsupervised method for the segmentation of retinal vessels images using a combined matched filter, Frangi's filter and Gabor Wavelet filter to enhance the images. The combination of these three filters in order to improve the segmentation is the main motivation of this work. We investigate two approaches to perform the filter combination: weighted mean and median ranking. Segmentation methods are tested after the vessel enhancement. Enhanced images with median ranking are segmented using a simple threshold criterion. Two segmentation procedures are applied when considering enhanced retinal images using the weighted mean approach. The first method is based on deformable models and the second uses fuzzy C-means for the image segmentation. The procedure is evaluated using two public image databases, Drive and Stare. The experimental results demonstrate that the proposed methods perform well for vessel segmentation in comparison with state-of-the-art methods.

  6. Inter-eye comparison of retinal oximetry and vessel caliber between eyes with asymmetrical glaucoma severity in different glaucoma subtypes

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    Cheng CS

    2016-07-01

    Full Text Available Clarissa Shu Ming Cheng,1,2 Yi Fang Lee,2 Charles Ong,3 Zhu Li Yap,2 Andrew Tsai,2 Aditi Mohla,2 Monisha E Nongpiur,4 Tin Aung,2,4 Shamira A Perera2,4 1Department of Ophthalmology, Tan Tock Seng Hospital, 2Department of Ophthalmology, Singapore National Eye Centre, 3Yong Loo Lin School of Medicine, National University of Singapore, 4Singapore Eye Research Institute, Singapore National Eye Centre, Singapore Background: To compare retinal vessel oxygenation and vessel caliber in primary angle-closure glaucoma (PACG, primary open-angle glaucoma (POAG, normal-tension glaucoma (NTG, and normal controls, as well as between eyes of asymmetrical glaucoma severity.Methods: This was a prospective, cross-sectional study. The 159 subjects (PACG, n=39; POAG, n=41; NTG, n=41; normal controls, n=38 underwent retinal oxygen saturation measurements using the Oxymap T1 Retinal Oximeter, optical coherence tomography, and Humphrey visual field testing. Retinal oxygen saturation and vessel diameter were compared between the glaucoma groups and normal controls, as well as between eyes of asymmetrical glaucoma severity. Kruskal–Wallis test was performed for comparison among different subtypes of glaucoma. Wilcoxon signed-rank test was used to compare the inter-eye differences.Results: Compared to normal controls, arteriolar oxygen saturation was increased in PACG eyes (P=0.048 but not in POAG or NTG eyes. There were no significant differences in oxygen saturation in venules or arteriovenous (AV difference in all three glaucoma groups. Venular diameter was significantly reduced in all glaucoma groups compared to normal controls (P<0.001, but no such change was observed in arteriolar diameter (P=0.10. When comparing between eyes of asymmetrical glaucoma severity, arteriolar oxygen saturation (P=0.03 and AV difference (P=0.04 were significantly higher, while arteriolar diameter was significantly lower (P=0.001 in the worse eye in PACG group. There were no significant

  7. Automatic segmentation of blood vessels from retinal fundus images ...

    Indian Academy of Sciences (India)

    The retinal blood vessels were segmented through color space conversion and color channel .... Retinal blood vessel segmentation was also attempted through multi-scale operators. A few works in this ... fundus camera at 35 degrees field of view. The image ... vessel segmentation is available from two human observers.

  8. Novel method for edge detection of retinal vessels based on the model of the retinal vascular network and mathematical morphology

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    Xu, Lei; Zheng, Xiaoxiang; Zhang, Hengyi; Yu, Yajun

    1998-09-01

    Accurate edge detection of retinal vessels is a prerequisite for quantitative analysis of subtle morphological changes of retinal vessels under different pathological conditions. A novel method for edge detection of retinal vessels is presented in this paper. Methods: (1) Wavelet-based image preprocessing. (2) The signed edge detection algorithm and mathematical morphological operation are applied to get the approximate regions that contain retinal vessels. (3) By convolving the preprocessed image with a LoG operator only on the detected approximate regions of retinal vessels, followed by edges refining, clear edge maps of the retinal vessels are fast obtained. Results: A detailed performance evaluation together with the existing techniques is given to demonstrate the strong features of our method. Conclusions: True edge locations of retinal vessels can be fast detected with continuous structures of retinal vessels, less non- vessel segments left and insensitivity to noise. The method is also suitable for other application fields such as road edge detection.

  9. Automated method for identification and artery-venous classification of vessel trees in retinal vessel networks.

    Science.gov (United States)

    Joshi, Vinayak S; Reinhardt, Joseph M; Garvin, Mona K; Abramoff, Michael D

    2014-01-01

    The separation of the retinal vessel network into distinct arterial and venous vessel trees is of high interest. We propose an automated method for identification and separation of retinal vessel trees in a retinal color image by converting a vessel segmentation image into a vessel segment map and identifying the individual vessel trees by graph search. Orientation, width, and intensity of each vessel segment are utilized to find the optimal graph of vessel segments. The separated vessel trees are labeled as primary vessel or branches. We utilize the separated vessel trees for arterial-venous (AV) classification, based on the color properties of the vessels in each tree graph. We applied our approach to a dataset of 50 fundus images from 50 subjects. The proposed method resulted in an accuracy of 91.44% correctly classified vessel pixels as either artery or vein. The accuracy of correctly classified major vessel segments was 96.42%.

  10. Relaxin 2 fails to lower intraocular pressure and to dilate retinal vessels in rats.

    Science.gov (United States)

    Hampel, Ulrike; Träger, Katharina; Liu, Hanhan; Teister, Julia; Grus, Franz; Prokosch-Willing, Verena

    2018-03-13

    Recently, the vasodilator relaxin 2 has been introduced as a treatment for acute heart failure. However, its role on vessels of the eye and intraocular pressure (IOP) remains unclear though it has been hypothesized to induce a decrease IOP after intramuscular injection in humans. We aimed to test whether the hormone relaxin 2 lowers IOP and dilates retinal vessels in animals. The IOP of female Sprague-Dawley rats before and after application of relaxin 2 was measured using an Icare Tonolab device calibrated for rats. Recombinant human relaxin 2 in phosphate-buffered saline with 0.1% bovine serum albumin was either applied as eye drops (1000, 2000 or 3000 ng/ml), injected intravitreally (500 ng/ml) or intravenously (13.3 μg/kg body weight). Retinal vessel thickness was monitored using infrared fundus images compiled with optical coherence tomography (Heidelberg Engineering) before and several time points after application of relaxin 2. Neither topical nor intravitreous or intravenous application of relaxin 2 lowered the IOP or changed the arterial or venous vessel diameter after 1 or 3 h after application. Now that relaxin 2 is more easily available, the hormone came again into focus as a potential glaucoma therapeutic. However, our study in rats could not support the hypothesis that relaxin 2 lowers IOP or dilates retinal vessels.

  11. Improvement of retinal blood vessel detection using morphological component analysis.

    Science.gov (United States)

    Imani, Elaheh; Javidi, Malihe; Pourreza, Hamid-Reza

    2015-03-01

    Detection and quantitative measurement of variations in the retinal blood vessels can help diagnose several diseases including diabetic retinopathy. Intrinsic characteristics of abnormal retinal images make blood vessel detection difficult. The major problem with traditional vessel segmentation algorithms is producing false positive vessels in the presence of diabetic retinopathy lesions. To overcome this problem, a novel scheme for extracting retinal blood vessels based on morphological component analysis (MCA) algorithm is presented in this paper. MCA was developed based on sparse representation of signals. This algorithm assumes that each signal is a linear combination of several morphologically distinct components. In the proposed method, the MCA algorithm with appropriate transforms is adopted to separate vessels and lesions from each other. Afterwards, the Morlet Wavelet Transform is applied to enhance the retinal vessels. The final vessel map is obtained by adaptive thresholding. The performance of the proposed method is measured on the publicly available DRIVE and STARE datasets and compared with several state-of-the-art methods. An accuracy of 0.9523 and 0.9590 has been respectively achieved on the DRIVE and STARE datasets, which are not only greater than most methods, but are also superior to the second human observer's performance. The results show that the proposed method can achieve improved detection in abnormal retinal images and decrease false positive vessels in pathological regions compared to other methods. Also, the robustness of the method in the presence of noise is shown via experimental result. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  12. Roi Detection and Vessel Segmentation in Retinal Image

    Science.gov (United States)

    Sabaz, F.; Atila, U.

    2017-11-01

    Diabetes disrupts work by affecting the structure of the eye and afterwards leads to loss of vision. Depending on the stage of disease that called diabetic retinopathy, there are sudden loss of vision and blurred vision problems. Automated detection of vessels in retinal images is a useful study to diagnose eye diseases, disease classification and other clinical trials. The shape and structure of the vessels give information about the severity of the disease and the stage of the disease. Automatic and fast detection of vessels allows for a quick diagnosis of the disease and the treatment process to start shortly. ROI detection and vessel extraction methods for retinal image are mentioned in this study. It is shown that the Frangi filter used in image processing can be successfully used in detection and extraction of vessels.

  13. ROI DETECTION AND VESSEL SEGMENTATION IN RETINAL IMAGE

    Directory of Open Access Journals (Sweden)

    F. Sabaz

    2017-11-01

    Full Text Available Diabetes disrupts work by affecting the structure of the eye and afterwards leads to loss of vision. Depending on the stage of disease that called diabetic retinopathy, there are sudden loss of vision and blurred vision problems. Automated detection of vessels in retinal images is a useful study to diagnose eye diseases, disease classification and other clinical trials. The shape and structure of the vessels give information about the severity of the disease and the stage of the disease. Automatic and fast detection of vessels allows for a quick diagnosis of the disease and the treatment process to start shortly. ROI detection and vessel extraction methods for retinal image are mentioned in this study. It is shown that the Frangi filter used in image processing can be successfully used in detection and extraction of vessels.

  14. Macular Retinal Vessel Oxygen Saturation Elevation in Chinese Central Serous Chorioretinopathy

    Directory of Open Access Journals (Sweden)

    Cheng Li

    2017-01-01

    Full Text Available Purpose. To evaluate the retinal vessel oxygen saturation in central serous chorioretinopathy (CSC cases among the Chinese. Methods. Relative oxygen saturation of retinal blood vessels was measured in 33 Chinese patients with single-eye CSC using the Oxymap T1 retinal oximeter. The contralateral eyes were the control. The mean saturation of the retinal arteriole (AS and venule (VS, arteriovenous difference (AVS, and arteriole and venule diameters (AD, VD was analyzed in the optic disc area and macular region. Results. In the optic disc area, the inferotemporal quadrant (TI AS (93.2 ± 10.2% and inferonasal quadrant (NI VS (61.3 ± 7.3% were higher in the affected eyes than in the contralateral eyes (88.7 ± 7.7% and 56.9 ± 6.5% and AVS in NI (36.7 ± 10.4% decreased compared to the contralateral eyes (41.5 ± 11.2%. The VD in TI was expanded (19.9 ± 2.5 pixels versus 18.1 ± 3.4 pixels. Around the macular region, AS was 93.6 ± 7.6%, higher than in the contralateral eyes (89.5 ± 6.3%. No other significant changes were found. Conclusions. AS increased in the TI, and VS decreased in the NI in the eyes with CSC. In addition, AS also increased around the macular region, suggesting that these are contributors to CSC pathophysiology.

  15. Semi-automated retinal vessel analysis in nonmydriatic fundus photography.

    Science.gov (United States)

    Schuster, Alexander Karl-Georg; Fischer, Joachim Ernst; Vossmerbaeumer, Urs

    2014-02-01

    Funduscopic assessment of the retinal vessels may be used to assess the health status of microcirculation and as a component in the evaluation of cardiovascular risk factors. Typically, the evaluation is restricted to morphological appreciation without strict quantification. Our purpose was to develop and validate a software tool for semi-automated quantitative analysis of retinal vasculature in nonmydriatic fundus photography. matlab software was used to develop a semi-automated image recognition and analysis tool for the determination of the arterial-venous (A/V) ratio in the central vessel equivalent on 45° digital fundus photographs. Validity and reproducibility of the results were ascertained using nonmydriatic photographs of 50 eyes from 25 subjects recorded from a 3DOCT device (Topcon Corp.). Two hundred and thirty-three eyes of 121 healthy subjects were evaluated to define normative values. A software tool was developed using image thresholds for vessel recognition and vessel width calculation in a semi-automated three-step procedure: vessel recognition on the photograph and artery/vein designation, width measurement and calculation of central retinal vessel equivalents. Mean vessel recognition rate was 78%, vessel class designation rate 75% and reproducibility between 0.78 and 0.91. Mean A/V ratio was 0.84. Application on a healthy norm cohort showed high congruence with prior published manual methods. Processing time per image was one minute. Quantitative geometrical assessment of the retinal vasculature may be performed in a semi-automated manner using dedicated software tools. Yielding reproducible numerical data within a short time leap, this may contribute additional value to mere morphological estimates in the clinical evaluation of fundus photographs. © 2013 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  16. A computational algorithm addressing how vessel length might depend on vessel diameter

    Science.gov (United States)

    Jing Cai; Shuoxin Zhang; Melvin T. Tyree

    2010-01-01

    The objective of this method paper was to examine a computational algorithm that may reveal how vessel length might depend on vessel diameter within any given stem or species. The computational method requires the assumption that vessels remain approximately constant in diameter over their entire length. When this method is applied to three species or hybrids in the...

  17. An automated vessel segmentation of retinal images using multiscale vesselness

    International Nuclear Information System (INIS)

    Ben Abdallah, M.; Malek, J.; Tourki, R.; Krissian, K.

    2011-01-01

    The ocular fundus image can provide information on pathological changes caused by local ocular diseases and early signs of certain systemic diseases, such as diabetes and hypertension. Automated analysis and interpretation of fundus images has become a necessary and important diagnostic procedure in ophthalmology. The extraction of blood vessels from retinal images is an important and challenging task in medical analysis and diagnosis. In this paper, we introduce an implementation of the anisotropic diffusion which allows reducing the noise and better preserving small structures like vessels in 2D images. A vessel detection filter, based on a multi-scale vesselness function, is then applied to enhance vascular structures.

  18. Retinal vessels caliber assessment in patients with arterial hypertension

    Directory of Open Access Journals (Sweden)

    N. S. Semenova

    2014-07-01

    Full Text Available Purpose: to evaluate the diagnostic capability of automated retinal vessels (RV caliber estimation for hypertensive angiopathy.Methods: this study included 146 patients (292 eyes with arterial hypertension. All the subjects underwent fundus photography and RV caliber estimation. the latter was performed using newly developed computer-based method for automated vessel detection and central retinal arteriolar and venular equivalents determination (CRAE & CRVE. Sensitivity, specificity, and reproducibility of the method were estimated.Results: the method of RV caliber assessment showed good reproducibility. the overall specificity and sensitivity were 74% and 80.77%, respectively. Computer-based method of retinal vascular caliber assessment revealed higher predictive value comparing with ophthalmoscopic assessment (AUC = 0.903 and 0.85, respectively. Retinal arteriolar and venular caliber and AVR tend to decrease with age. Higher blood pressure is associated with narrower retinal arterioles.Conclusion: Novel method of RV caliber estimation demonstrated high information value. these findings are in good agreementwith data from major population-based studies.

  19. Retinal vessels caliber assessment in patients with arterial hypertension

    Directory of Open Access Journals (Sweden)

    N. S. Semenova

    2012-01-01

    Full Text Available Purpose: to evaluate the diagnostic capability of automated retinal vessels (RV caliber estimation for hypertensive angiopathy.Methods: this study included 146 patients (292 eyes with arterial hypertension. All the subjects underwent fundus photography and RV caliber estimation. the latter was performed using newly developed computer-based method for automated vessel detection and central retinal arteriolar and venular equivalents determination (CRAE & CRVE. Sensitivity, specificity, and reproducibility of the method were estimated.Results: the method of RV caliber assessment showed good reproducibility. the overall specificity and sensitivity were 74% and 80.77%, respectively. Computer-based method of retinal vascular caliber assessment revealed higher predictive value comparing with ophthalmoscopic assessment (AUC = 0.903 and 0.85, respectively. Retinal arteriolar and venular caliber and AVR tend to decrease with age. Higher blood pressure is associated with narrower retinal arterioles.Conclusion: Novel method of RV caliber estimation demonstrated high information value. these findings are in good agreementwith data from major population-based studies.

  20. Platform image processing to study the structural properties of retinal vessel

    Directory of Open Access Journals (Sweden)

    Miguel Ángel MERCHÁN

    2013-05-01

    Full Text Available This paper presents a technological platform specialized in assessing retinal vessel caliber and describing the relationship of the results obtained to cardiovascular risk. Retinal circulation is an area of active research by numerous groups, and there is general experimental agreement on the analysis of the patterns of the retinal blood vessels in the normal human retina. The development of automated tools designed to improve performance and decrease interobserver variability, therefore, appears necessary. 

  1. Comparative Study of Retinal Vessel Segmentation Based on Global Thresholding Techniques

    Directory of Open Access Journals (Sweden)

    Temitope Mapayi

    2015-01-01

    Full Text Available Due to noise from uneven contrast and illumination during acquisition process of retinal fundus images, the use of efficient preprocessing techniques is highly desirable to produce good retinal vessel segmentation results. This paper develops and compares the performance of different vessel segmentation techniques based on global thresholding using phase congruency and contrast limited adaptive histogram equalization (CLAHE for the preprocessing of the retinal images. The results obtained show that the combination of preprocessing technique, global thresholding, and postprocessing techniques must be carefully chosen to achieve a good segmentation performance.

  2. Retinal vascular and structural dynamics during acute hyperglycaemia

    DEFF Research Database (Denmark)

    Klefter, Oliver N; Lauritsen, Tina Vilsbøll; Knop, Filip K

    2015-01-01

    PURPOSE: To compare retinal vascular dynamics during acute hyperglycaemia in patients with type 2 diabetes and healthy volunteers. METHODS: Twenty-one patients with type 2 diabetes and 27 healthy controls were examined with fundus photographic measurement of retinal vessel diameters, retinal...

  3. NOVEL PRERETINAL HAIR PIN-LIKE VESSEL IN RETINAL ASTROCYTIC HAMARTOMA WITH VITREOUS HEMORRHAGE.

    Science.gov (United States)

    Soeta, Megumi; Arai, Yusuke; Takahashi, Hidenori; Fujino, Yujiro; Tanabe, Tatsuro; Inoue, Yuji; Kawashima, Hidetoshi

    2018-01-01

    To report a case of retinal astrocytic hamartoma with vitreous hemorrhage and a hair pin-like vessel adhering to a posterior vitreous membrane. A 33-year-old man with a retinal astrocytic hamartoma presented with vitreous hemorrhage 5 times. Multimodal imaging, including fundus photography, fluorescein angiography, optical coherence tomography, and B-mode ultrasonography. Multimodal imaging demonstrated a novel hair pin-like vessel that adhered to the posterior vitreous membrane. Some cases of retinal astrocytic hamartoma with vitreous hemorrhage may be related to structure abnormalities of tumor vessels.

  4. Multi-level deep supervised networks for retinal vessel segmentation.

    Science.gov (United States)

    Mo, Juan; Zhang, Lei

    2017-12-01

    Changes in the appearance of retinal blood vessels are an important indicator for various ophthalmologic and cardiovascular diseases, including diabetes, hypertension, arteriosclerosis, and choroidal neovascularization. Vessel segmentation from retinal images is very challenging because of low blood vessel contrast, intricate vessel topology, and the presence of pathologies such as microaneurysms and hemorrhages. To overcome these challenges, we propose a neural network-based method for vessel segmentation. A deep supervised fully convolutional network is developed by leveraging multi-level hierarchical features of the deep networks. To improve the discriminative capability of features in lower layers of the deep network and guide the gradient back propagation to overcome gradient vanishing, deep supervision with auxiliary classifiers is incorporated in some intermediate layers of the network. Moreover, the transferred knowledge learned from other domains is used to alleviate the issue of insufficient medical training data. The proposed approach does not rely on hand-crafted features and needs no problem-specific preprocessing or postprocessing, which reduces the impact of subjective factors. We evaluate the proposed method on three publicly available databases, the DRIVE, STARE, and CHASE_DB1 databases. Extensive experiments demonstrate that our approach achieves better or comparable performance to state-of-the-art methods with a much faster processing speed, making it suitable for real-world clinical applications. The results of cross-training experiments demonstrate its robustness with respect to the training set. The proposed approach segments retinal vessels accurately with a much faster processing speed and can be easily applied to other biomedical segmentation tasks.

  5. Automatic detection of blood vessels in retinal images for diabetic retinopathy diagnosis.

    Science.gov (United States)

    Raja, D Siva Sundhara; Vasuki, S

    2015-01-01

    Diabetic retinopathy (DR) is a leading cause of vision loss in diabetic patients. DR is mainly caused due to the damage of retinal blood vessels in the diabetic patients. It is essential to detect and segment the retinal blood vessels for DR detection and diagnosis, which prevents earlier vision loss in diabetic patients. The computer aided automatic detection and segmentation of blood vessels through the elimination of optic disc (OD) region in retina are proposed in this paper. The OD region is segmented using anisotropic diffusion filter and subsequentially the retinal blood vessels are detected using mathematical binary morphological operations. The proposed methodology is tested on two different publicly available datasets and achieved 93.99% sensitivity, 98.37% specificity, 98.08% accuracy in DRIVE dataset and 93.6% sensitivity, 98.96% specificity, and 95.94% accuracy in STARE dataset, respectively.

  6. Improvement of retinal blood vessel detection by spur removal and Gaussian matched filtering compensation

    Science.gov (United States)

    Xiao, Di; Vignarajan, Janardhan; An, Dong; Tay-Kearney, Mei-Ling; Kanagasingam, Yogi

    2016-03-01

    Retinal photography is a non-invasive and well-accepted clinical diagnosis of ocular diseases. Qualitative and quantitative assessment of retinal images is crucial in ocular diseases related clinical application. In this paper, we proposed approaches for improving the quality of blood vessel detection based on our initial blood vessel detection methods. A blood vessel spur pruning method has been developed for removing the blood vessel spurs both on vessel medial lines and binary vessel masks, which are caused by artifacts and side-effect of Gaussian matched vessel enhancement. A Gaussian matched filtering compensation method has been developed for removing incorrect vessel branches in the areas of low illumination. The proposed approaches were applied and tested on the color fundus images from one publicly available database and our diabetic retinopathy screening dataset. A preliminary result has demonstrated the robustness and good performance of the proposed approaches and their potential application for improving retinal blood vessel detection.

  7. Automated artery-venous classification of retinal blood vessels based on structural mapping method

    Science.gov (United States)

    Joshi, Vinayak S.; Garvin, Mona K.; Reinhardt, Joseph M.; Abramoff, Michael D.

    2012-03-01

    Retinal blood vessels show morphologic modifications in response to various retinopathies. However, the specific responses exhibited by arteries and veins may provide a precise diagnostic information, i.e., a diabetic retinopathy may be detected more accurately with the venous dilatation instead of average vessel dilatation. In order to analyze the vessel type specific morphologic modifications, the classification of a vessel network into arteries and veins is required. We previously described a method for identification and separation of retinal vessel trees; i.e. structural mapping. Therefore, we propose the artery-venous classification based on structural mapping and identification of color properties prominent to the vessel types. The mean and standard deviation of each of green channel intensity and hue channel intensity are analyzed in a region of interest around each centerline pixel of a vessel. Using the vector of color properties extracted from each centerline pixel, it is classified into one of the two clusters (artery and vein), obtained by the fuzzy-C-means clustering. According to the proportion of clustered centerline pixels in a particular vessel, and utilizing the artery-venous crossing property of retinal vessels, each vessel is assigned a label of an artery or a vein. The classification results are compared with the manually annotated ground truth (gold standard). We applied the proposed method to a dataset of 15 retinal color fundus images resulting in an accuracy of 88.28% correctly classified vessel pixels. The automated classification results match well with the gold standard suggesting its potential in artery-venous classification and the respective morphology analysis.

  8. Rotation invariant eigenvessels and auto-context for retinal vessel detection

    Science.gov (United States)

    Montuoro, Alessio; Simader, Christian; Langs, Georg; Schmidt-Erfurth, Ursula

    2015-03-01

    Retinal vessels are one of the few anatomical landmarks that are clearly visible in various imaging modalities of the eye. As they are also relatively invariant to disease progression, retinal vessel segmentation allows cross-modal and temporal registration enabling exact diagnosing for various eye diseases like diabetic retinopathy, hypertensive retinopathy or age-related macular degeneration (AMD). Due to the clinical significance of retinal vessels many different approaches for segmentation have been published in the literature. In contrast to other segmentation approaches our method is not specifically tailored to the task of retinal vessel segmentation. Instead we utilize a more general image classification approach and show that this can achieve comparable results. In the proposed method we utilize the concepts of eigenfaces and auto-context. Eigenfaces have been described quite extensively in the literature and their performance is well known. They are however quite sensitive to translation and rotation. The former was addressed by computing the eigenvessels in local image windows of different scales, the latter by estimating and correcting the local orientation. Auto-context aims to incorporate automatically generated context information into the training phase of classification approaches. It has been shown to improve the performance of spinal cord segmentation4 and 3D brain image segmentation. The proposed method achieves an area under the receiver operating characteristic (ROC) curve of Az = 0.941 on the DRIVE data set, being comparable to current state-of-the-art approaches.

  9. Vessel Sampling and Blood Flow Velocity Distribution With Vessel Diameter for Characterizing the Human Bulbar Conjunctival Microvasculature.

    Science.gov (United States)

    Wang, Liang; Yuan, Jin; Jiang, Hong; Yan, Wentao; Cintrón-Colón, Hector R; Perez, Victor L; DeBuc, Delia C; Feuer, William J; Wang, Jianhua

    2016-03-01

    This study determined (1) how many vessels (i.e., the vessel sampling) are needed to reliably characterize the bulbar conjunctival microvasculature and (2) if characteristic information can be obtained from the distribution histogram of the blood flow velocity and vessel diameter. Functional slitlamp biomicroscope was used to image hundreds of venules per subject. The bulbar conjunctiva in five healthy human subjects was imaged on six different locations in the temporal bulbar conjunctiva. The histograms of the diameter and velocity were plotted to examine whether the distribution was normal. Standard errors were calculated from the standard deviation and vessel sample size. The ratio of the standard error of the mean over the population mean was used to determine the sample size cutoff. The velocity was plotted as a function of the vessel diameter to display the distribution of the diameter and velocity. The results showed that the sampling size was approximately 15 vessels, which generated a standard error equivalent to 15% of the population mean from the total vessel population. The distributions of the diameter and velocity were not only unimodal, but also somewhat positively skewed and not normal. The blood flow velocity was related to the vessel diameter (r=0.23, Psampling size of the vessels and the distribution histogram of the blood flow velocity and vessel diameter, which may lead to a better understanding of the human microvascular system of the bulbar conjunctiva.

  10. [Static Retinal Vessel Analysis in Population-based Study SHIP-Trend].

    Science.gov (United States)

    Theophil, Constanze; Jürgens, Clemens; Großjohann, Rico; Kempin, Robert; Ittermann, Till; Nauck, Matthias; Völzke, Henry; Tost, Frank H W

    2017-08-24

    Background Interdisciplinary investigations of possible connections between general diseases and ophthalmological changes are difficult to perform in the clinical environment. But they are gaining in importance as a result of the age-related increase in chronic diseases. The collection of health-related parameters in the Study of Health in Pomerania (SHIP) project allows to derive conclusions for the general population. Methods The population-based SHIP trend study was conducted between 2008 and 2012 in Greifswald. The baseline cohort included 4420 subjects (response 50.1%) at the age of 20 to 84 years. The pre-existence of arterial hypertension, diabetes mellitus and smoking status were questioned in a standardized questionnaire, the blood pressure and the HbA 1c were determined by the laboratory. The vascular diameter of retinal arterioles and venules were determined by means of non-mydriatic fundus images and the retinal arterial (CRAE) and venous equivalent (CRVE) were calculated therefrom. The association of diabetes mellitus, HbA 1c , smoking status and blood pressure with the retinal vascular parameters was tested for age and sex with linear regression models. Results In 3218 subjects with evaluable standardized fundus photographs, significant associations of elevated HbA 1c (> 6.5%), smoking status and systolic and diastolic blood pressure were found with the retinal vessel widths CRAE and CRVE. Anamnestic diabetes mellitus, on the other hand, was not associated with any of the vascular parameters. Conclusion This research study reveals a relevant correlation between general diseases and the retinal blood flow in the eye. Therefore, general diseases can induce ophthalmological changes and eye examination can provide information for the assessment of general diseases. Georg Thieme Verlag KG Stuttgart · New York.

  11. Neonatal systemic inflammation in rats alters retinal vessel development and simulates pathologic features of retinopathy of prematurity.

    Science.gov (United States)

    Hong, Hye Kyoung; Lee, Hyun Ju; Ko, Jung Hwa; Park, Ji Hyun; Park, Ji Yeon; Choi, Chang Won; Yoon, Chang-Hwan; Ahn, Seong Joon; Park, Kyu Hyung; Woo, Se Joon; Oh, Joo Youn

    2014-05-15

    Alteration of retinal angiogenesis during development leads to retinopathy of prematurity (ROP) in preterm infants, which is a leading cause of visual impairment in children. A number of clinical studies have reported higher rates of ROP in infants who had perinatal infections or inflammation, suggesting that exposure of the developing retina to inflammation may disturb retinal vessel development. Thus, we investigated the effects of systemic inflammation on retinal vessel development and retinal inflammation in neonatal rats. To induce systemic inflammation, we intraperitoneally injected 100 μl lipopolysaccharide (LPS, 0.25 mg/ml) or the same volume of normal saline in rat pups on postnatal days 1, 3, and 5. The retinas were extracted on postnatal days 7 and 14, and subjected to assays for retinal vessels, inflammatory cells and molecules, and apoptosis. We found that intraperitoneal injection of LPS impaired retinal vessel development by decreasing vessel extension, reducing capillary density, and inducing localized overgrowth of abnormal retinal vessels and dilated peripheral vascular ridge, all of which are characteristic findings of ROP. Also, a large number of CD11c+ inflammatory cells and astrocytes were localized in the lesion of abnormal vessels. Further analysis revealed that the number of major histocompatibility complex (MHC) class IIloCD68loCD11bloCD11chi cells in the retina was higher in LPS-treated rats compared to controls. Similarly, the levels of TNF-α, IL-1β, and IL-12a were increased in LPS-treated retina. Also, apoptosis was increased in the inner retinal layer where retinal vessels are located. Our data demonstrate that systemic LPS-induced inflammation elicits retinal inflammation and impairs retinal angiogenesis in neonatal rats, implicating perinatal inflammation in the pathogenesis of ROP.

  12. The blood pressure-induced diameter response of retinal arterioles decreases with increasing diabetic maculopathy

    DEFF Research Database (Denmark)

    Frederiksen, Christian Alcaraz; Jeppesen, Peter; Knudsen, Søren Tang

    2006-01-01

    A consisted of normal individuals and groups B-D consisted of type 2 diabetic patients matched for diabetes duration, age, and gender, and characterized by: Group B no retinopathy, Group C mild retinopathy, Group D maculopathy not requiring laser treatment. The diameter changes of a large retinal arteriole......+/-4.5 microm), and Group C (253+/-4.4 microm), but was significantly (p=0.006) increased in Group D (279+/-5.3 microm). CONCLUSIONS: The diameter response was reduced in type 2 diabetic patients with retinopathy, whereas retinal thickness was increased in patients with diabetic maculopathy. This suggests......BACKGROUND: The aim of the study was to compare the diameter response of retinal arterioles and retinal thickness in patients with different stages of diabetic maculopathy during an increase in the arterial blood pressure. METHODS: Four groups each consisting of 19 individuals were studied. Group...

  13. 3-D segmentation of retinal blood vessels in spectral-domain OCT volumes of the optic nerve head

    Science.gov (United States)

    Lee, Kyungmoo; Abràmoff, Michael D.; Niemeijer, Meindert; Garvin, Mona K.; Sonka, Milan

    2010-03-01

    Segmentation of retinal blood vessels can provide important information for detecting and tracking retinal vascular diseases including diabetic retinopathy, arterial hypertension, arteriosclerosis and retinopathy of prematurity (ROP). Many studies on 2-D segmentation of retinal blood vessels from a variety of medical images have been performed. However, 3-D segmentation of retinal blood vessels from spectral-domain optical coherence tomography (OCT) volumes, which is capable of providing geometrically accurate vessel models, to the best of our knowledge, has not been previously studied. The purpose of this study is to develop and evaluate a method that can automatically detect 3-D retinal blood vessels from spectral-domain OCT scans centered on the optic nerve head (ONH). The proposed method utilized a fast multiscale 3-D graph search to segment retinal surfaces as well as a triangular mesh-based 3-D graph search to detect retinal blood vessels. An experiment on 30 ONH-centered OCT scans (15 right eye scans and 15 left eye scans) from 15 subjects was performed, and the mean unsigned error in 3-D of the computer segmentations compared with the independent standard obtained from a retinal specialist was 3.4 +/- 2.5 voxels (0.10 +/- 0.07 mm).

  14. A thresholding based technique to extract retinal blood vessels from fundus images

    Directory of Open Access Journals (Sweden)

    Jyotiprava Dash

    2017-12-01

    Full Text Available Retinal imaging has become the significant tool among all the medical imaging technology, due to its capability to extract many data which is linked to various eye diseases. So, the accurate extraction of blood vessel is necessary that helps the eye care specialists and ophthalmologist to identify the diseases at the early stages. In this paper, we have proposed a computerized technique for extraction of blood vessels from fundus images. The process is conducted in three phases: (i pre-processing where the image is enhanced using contrast limited adaptive histogram equalization and median filter, (ii segmentation using mean-C thresholding to extract retinal blood vessels, (iii post-processing where morphological cleaning operation is used to remove isolated pixels. The performance of the proposed method is tested on and experimental results show that our method achieve an accuracies of 0.955 and 0.954 on Digital retinal images for vessel extraction (DRIVE and Child heart and health study in England (CHASE_DB1 databases respectively.

  15. In 6- to 8-year-old children, hair cortisol is associated with body mass index and somatic complaints, but not with stress, health-related quality of life, blood pressure, retinal vessel diameters, and cardiorespiratory fitness.

    Science.gov (United States)

    Gerber, Markus; Endes, Katharina; Brand, Serge; Herrmann, Christian; Colledge, Flora; Donath, Lars; Faude, Oliver; Pühse, Uwe; Hanssen, Henner; Zahner, Lukas

    2017-02-01

    Hair cortisol measurement has become an increasingly accepted approach in endocrinology and biopsychology. However, while in adult research hair cortisol has been proposed as a relevant biomarker for chronic stress (and its adverse consequences), studies with children are scarce. Therefore, the goal of the present exploratory study was to examine the associations between hair cortisol concentrations (HCCs), stress, and a series of health-related outcomes in a sample of Swiss first grade schoolchildren. The sample consisted of 318 children (53% girls, M age =7.26, SD=0.35). Hair strands were taken near the scalp from a posterior vertex position, and HCCs were tested for the first 3-cm hair segment. Parents provided information about their children's age, gender, parental education, children's stress (recent critical life events, daily hassles), health-related quality of life, and psychosomatic complaints. Body composition, blood pressure, retinal vessel diameters, and cardiorespiratory fitness were measured with established methods. In multiple regression analyses, higher HCCs were weakly associated with increased BMI in girls (β=0.22, pstress, health-related quality of life, blood pressure, retinal vessel diameters, and cardiorespiratory fitness. Although small significant relationships were found between HCCs, BMI and somatic complaints, the findings of this exploratory study challenge the view that HCCs can be used as a reliable biomarker of recent critical life events, daily hassles, health-related quality of life, and cardiovascular health indicators in non-clinical young children. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. A Review of Algorithms for Retinal Vessel Segmentation

    Directory of Open Access Journals (Sweden)

    Monserrate Intriago Pazmiño

    2014-10-01

    Full Text Available This paper presents a review of algorithms for extracting blood vessels network from retinal images. Since retina is a complex and delicate ocular structure, a huge effort in computer vision is devoted to study blood vessels network for helping the diagnosis of pathologies like diabetic retinopathy, hypertension retinopathy, retinopathy of prematurity or glaucoma. To carry out this process many works for normal and abnormal images have been proposed recently. These methods include combinations of algorithms like Gaussian and Gabor filters, histogram equalization, clustering, binarization, motion contrast, matched filters, combined corner/edge detectors, multi-scale line operators, neural networks, ants, genetic algorithms, morphological operators. To apply these algorithms pre-processing tasks are needed. Most of these algorithms have been tested on publicly retinal databases. We have include a table summarizing algorithms and results of their assessment.

  17. In-vivo imaging of blood flow in human retinal vessels using color Doppler optical coherence tomography

    Science.gov (United States)

    Yazdanfar, Siavash; Rollins, Andrew M.; Izatt, Joseph A.

    1999-04-01

    Quantification of retinal blood flow may lead to a better understanding of the progression and treatment of several ocular disorders, including diabetic retinopathy, age- related macular degeneration, and glaucoma. Current techniques, such as fluorescein angiography and laser Doppler velocimetry are limited, failing to provide sufficient information to the clinician. Color Doppler optical coherence tomography (CDOCT) is a novel technique using coherent heterodyne detection for simultaneous cross- sectional imaging of tissue microstructure and blood flow. This technique is capable of high spatial and velocity resolution imaging in highly scattering media. We implemented CDOCT for retinal blood flow mapping in human subjects. No dilation of the pupil was necessary. CDOCT is demonstrated for determining bidirectional flow in sub- 100micrometers diameter vessels in the retina. Additionally, we calculated Doppler broadening using the variance of depth- resolved spectra to identify regions with large velocity gradients within the Xenopus heart. This technique may be useful in quantifying local tissue perfusion in highly vascular retinal tissue.

  18. Evidence of Flicker-Induced Functional Hyperaemia in the Smallest Vessels of the Human Retinal Blood Supply.

    Directory of Open Access Journals (Sweden)

    Angelina Duan

    Full Text Available Regional changes in blood flow are initiated within neural tissue to help fuel local differences in neural activity. Classically, this response was thought to arise only in larger arterioles and venules. However, recently, it has been proposed that a the smallest vessels of the circulation make a comparable contribution, and b the response should be localised intermittently along such vessels, due to the known distribution of contractile mural cells. To assess these hypotheses in human neural tissue in vivo, we imaged the retinal microvasculature (diameters 3-28 μm non-invasively, using adaptive optics, before and after delivery of focal (360 μm patches of flickering visible light. Our results demonstrated a definite average response in 35% of all vessel segments analysed. In these responding vessels, the magnitude of proportional dilation (mean ± SEM for pre-capillary arterioles 13 ± 5%, capillaries 31 ± 8%, and post-capillary venules 10 ± 3% is generally far greater than the magnitudes we and others have measured in the larger retinal vessels, supporting proposition a above. The dilations observed in venules were unexpected based on previous animal work, and may be attributed either to differences in stimulus or species. Response heterogeneity across the network was high; responses were also heterogeneous along individual vessels (45% of vessel segments showed demonstrable locality in their response. These observations support proposition b above. We also observed a definite average constriction across 7% of vessel segments (mean ± SEM constriction for capillaries -16 ± 3.2%, and post-capillary venules -18 ± 12%, which paints a picture of dynamic redistribution of flow throughout the smallest vessel networks in the retina in response to local, stimulus-driven metabolic demand.

  19. Retinal blood vessel extraction using tunable bandpass filter and fuzzy conditional entropy.

    Science.gov (United States)

    Sil Kar, Sudeshna; Maity, Santi P

    2016-09-01

    Extraction of blood vessels on retinal images plays a significant role for screening of different opthalmologic diseases. However, accurate extraction of the entire and individual type of vessel silhouette from the noisy images with poorly illuminated background is a complicated task. To this aim, an integrated system design platform is suggested in this work for vessel extraction using a sequential bandpass filter followed by fuzzy conditional entropy maximization on matched filter response. At first noise is eliminated from the image under consideration through curvelet based denoising. To include the fine details and the relatively less thick vessel structures, the image is passed through a bank of sequential bandpass filter structure optimized for contrast enhancement. Fuzzy conditional entropy on matched filter response is then maximized to find the set of multiple optimal thresholds to extract the different types of vessel silhouettes from the background. Differential Evolution algorithm is used to determine the optimal gain in bandpass filter and the combination of the fuzzy parameters. Using the multiple thresholds, retinal image is classified as the thick, the medium and the thin vessels including neovascularization. Performance evaluated on different publicly available retinal image databases shows that the proposed method is very efficient in identifying the diverse types of vessels. Proposed method is also efficient in extracting the abnormal and the thin blood vessels in pathological retinal images. The average values of true positive rate, false positive rate and accuracy offered by the method is 76.32%, 1.99% and 96.28%, respectively for the DRIVE database and 72.82%, 2.6% and 96.16%, respectively for the STARE database. Simulation results demonstrate that the proposed method outperforms the existing methods in detecting the various types of vessels and the neovascularization structures. The combination of curvelet transform and tunable bandpass

  20. Segmentation of retinal blood vessels for detection of diabetic retinopathy: A review

    Directory of Open Access Journals (Sweden)

    Rezty Amalia Aras

    2016-05-01

    Full Text Available Diabetic detinopathy (DR is effect of diabetes mellitus to the human vision that is the major cause of blindness. Early diagnosis of DR is an important requirement in diabetes treatment. Retinal fundus image is commonly used to observe the diabetic retinopathy symptoms. It can present retinal features such as blood vessel and also capture the pathologies which may lead to DR. Blood vessel is one of retinal features which can show the retina pathologies. It can be extracted from retinal image by image processing with following stages: pre-processing, segmentation, and post-processing. This paper contains a review of public retinal image dataset and several methods from various conducted researches. All discussed methods are applicable to each researcher cases. There is no further analysis to conclude the best method which can be used for general cases. However, we suggest morphological and multiscale method that gives the best accuracy in segmentation.

  1. AN EFFICIENT TECHNIQUE FOR RETINAL VESSEL SEGMENTATION AND DENOISING USING MODIFIED ISODATA AND CLAHE

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    Khan Bahadar Khan

    2016-11-01

    Full Text Available Retinal damage caused due to complications of diabetes is known as Diabetic Retinopathy (DR. In this case, the vision is obscured due to the damage of retinal tinny blood vessels of the retina. These tinny blood vessels may cause leakage which affect the vision and can lead to complete blindness. Identification of these new retinal vessels and their structure is essential for analysis of DR. Automatic blood vessels segmentation plays a significant role to assist subsequent automatic methodologies that aid to such analysis. In literature most of the people have used computationally hungry a strong preprocessing steps followed by a simple thresholding and post processing, But in our proposed technique we utilize an arrangement of  light pre-processing which consists of Contrast Limited Adaptive Histogram Equalization (CLAHE for contrast enhancement, a difference image of green channel from its Gaussian blur filtered image to remove local noise or geometrical object, Modified Iterative Self Organizing Data Analysis Technique (MISODATA for segmentation of vessel and non-vessel pixels based on global and local thresholding, and a strong  post processing using region properties (area, eccentricity to eliminate the unwanted region/segment, non-vessel pixels and noise that never been used to reject misclassified foreground pixels. The strategy is tested on the publically accessible DRIVE (Digital Retinal Images for Vessel Extraction and STARE (STructured Analysis of the REtina databases. The performance of proposed technique is assessed comprehensively and the acquired accuracy, robustness, low complexity and high efficiency and very less computational time that make the method an efficient tool for automatic retinal image analysis. Proposed technique perform well as compared to the existing strategies on the online available databases in term of accuracy, sensitivity, specificity, false positive rate, true positive rate and area under receiver

  2. Fast vessel segmentation in retinal images using multi-scale enhancement and second-order local entropy

    Science.gov (United States)

    Yu, H.; Barriga, S.; Agurto, C.; Zamora, G.; Bauman, W.; Soliz, P.

    2012-03-01

    Retinal vasculature is one of the most important anatomical structures in digital retinal photographs. Accurate segmentation of retinal blood vessels is an essential task in automated analysis of retinopathy. This paper presents a new and effective vessel segmentation algorithm that features computational simplicity and fast implementation. This method uses morphological pre-processing to decrease the disturbance of bright structures and lesions before vessel extraction. Next, a vessel probability map is generated by computing the eigenvalues of the second derivatives of Gaussian filtered image at multiple scales. Then, the second order local entropy thresholding is applied to segment the vessel map. Lastly, a rule-based decision step, which measures the geometric shape difference between vessels and lesions is applied to reduce false positives. The algorithm is evaluated on the low-resolution DRIVE and STARE databases and the publicly available high-resolution image database from Friedrich-Alexander University Erlangen-Nuremberg, Germany). The proposed method achieved comparable performance to state of the art unsupervised vessel segmentation methods with a competitive faster speed on the DRIVE and STARE databases. For the high resolution fundus image database, the proposed algorithm outperforms an existing approach both on performance and speed. The efficiency and robustness make the blood vessel segmentation method described here suitable for broad application in automated analysis of retinal images.

  3. Blood Vessel Extraction in Color Retinal Fundus Images with Enhancement Filtering and Unsupervised Classification

    Directory of Open Access Journals (Sweden)

    Zafer Yavuz

    2017-01-01

    Full Text Available Retinal blood vessels have a significant role in the diagnosis and treatment of various retinal diseases such as diabetic retinopathy, glaucoma, arteriosclerosis, and hypertension. For this reason, retinal vasculature extraction is important in order to help specialists for the diagnosis and treatment of systematic diseases. In this paper, a novel approach is developed to extract retinal blood vessel network. Our method comprises four stages: (1 preprocessing stage in order to prepare dataset for segmentation; (2 an enhancement procedure including Gabor, Frangi, and Gauss filters obtained separately before a top-hat transform; (3 a hard and soft clustering stage which includes K-means and Fuzzy C-means (FCM in order to get binary vessel map; and (4 a postprocessing step which removes falsely segmented isolated regions. The method is tested on color retinal images obtained from STARE and DRIVE databases which are available online. As a result, Gabor filter followed by K-means clustering method achieves 95.94% and 95.71% of accuracy for STARE and DRIVE databases, respectively, which are acceptable for diagnosis systems.

  4. Spontaneous high frequency diameter oscillations of larger retinal arterioles are reduced in type 2 diabetes mellitus

    DEFF Research Database (Denmark)

    Bek, Toke; Jeppesen, Peter; Kanters, Jørgen K.

    2013-01-01

    Diabetic retinopathy is characterized by morphological changes in the retina secondary to disturbances in retinal blood flow. Vasomotion is a mechanism for regulating blood flow by spontaneous oscillations in the diameter of retinal resistance arterioles, and has been shown to be disturbed outside...... the eye in diabetic patients. Therefore, the purpose of the present study was to characterize spontaneous oscillations in the diameter of retinal arterioles in normal persons and in persons with different severity of diabetic retinopathy....

  5. Vessel Segmentation in Retinal Images Using Multi-scale Line Operator and K-Means Clustering.

    Science.gov (United States)

    Saffarzadeh, Vahid Mohammadi; Osareh, Alireza; Shadgar, Bita

    2014-04-01

    Detecting blood vessels is a vital task in retinal image analysis. The task is more challenging with the presence of bright and dark lesions in retinal images. Here, a method is proposed to detect vessels in both normal and abnormal retinal fundus images based on their linear features. First, the negative impact of bright lesions is reduced by using K-means segmentation in a perceptive space. Then, a multi-scale line operator is utilized to detect vessels while ignoring some of the dark lesions, which have intensity structures different from the line-shaped vessels in the retina. The proposed algorithm is tested on two publicly available STARE and DRIVE databases. The performance of the method is measured by calculating the area under the receiver operating characteristic curve and the segmentation accuracy. The proposed method achieves 0.9483 and 0.9387 localization accuracy against STARE and DRIVE respectively.

  6. A robust technique based on VLM and Frangi filter for retinal vessel extraction and denoising.

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    Khan Bahadar Khan

    Full Text Available The exploration of retinal vessel structure is colossally important on account of numerous diseases including stroke, Diabetic Retinopathy (DR and coronary heart diseases, which can damage the retinal vessel structure. The retinal vascular network is very hard to be extracted due to its spreading and diminishing geometry and contrast variation in an image. The proposed technique consists of unique parallel processes for denoising and extraction of blood vessels in retinal images. In the preprocessing section, an adaptive histogram equalization enhances dissimilarity between the vessels and the background and morphological top-hat filters are employed to eliminate macula and optic disc, etc. To remove local noise, the difference of images is computed from the top-hat filtered image and the high-boost filtered image. Frangi filter is applied at multi scale for the enhancement of vessels possessing diverse widths. Segmentation is performed by using improved Otsu thresholding on the high-boost filtered image and Frangi's enhanced image, separately. In the postprocessing steps, a Vessel Location Map (VLM is extracted by using raster to vector transformation. Postprocessing steps are employed in a novel way to reject misclassified vessel pixels. The final segmented image is obtained by using pixel-by-pixel AND operation between VLM and Frangi output image. The method has been rigorously analyzed on the STARE, DRIVE and HRF datasets.

  7. Impaired Retinal Vasodilator Responses in Prediabetes and Type 2 Diabetes

    Science.gov (United States)

    Lott, Mary E.J.; Slocomb, Julia E.; Shivkumar, Vikram; Smith, Bruce; Quillen, David; Gabbay, Robert A.; Gardner, Thomas W.; Bettermann, Kerstin

    2013-01-01

    Purpose In diabetes, endothelial dysfunction and subsequent structural damage to blood vessels can lead to heart attacks, retinopathy and strokes. However, it is unclear whether prediabetic subjects exhibit microvascular dysfunction indicating early stages of arteriosclerosis and vascular risk. The purpose of this study was to examine whether retinal reactivity may be impaired early in the hyperglycemic continuum and may be associated with markers of inflammation. Methods Individuals with prediabetes (n = 22), type 2 diabetes (n = 25) and healthy age and body composition matched controls (n = 19) were studied. We used the Dynamic Vessel Analyzer to assess retinal vasoreactivity (percent change in vessel diameter) during a flickering light stimulation. Fasting highly sensitive c-reactive protein (hs-CRP), a marker of inflammation, was measured in blood plasma. Results Prediabetic and diabetic individuals had attenuated peak vasodilator and relative amplitude changes in retinal vein diameters to the flickering light stimulus compared to healthy controls (peak dilation: prediabetic subjects 3.3 ± 1.8 %, diabetic subjects 3.3 ± 2.1% controls 5.6 ± 2.6%, p = .001; relative amplitude: prediabetic subjects 4.3 ± 2.2%, diabetic subjects 5.0 ± 2.6% and control subjects 7.2 ± 3.2%, p = .003). Similar findings were observed in retinal arteries. Levels of hs-CRP were not associated with either retinal vessel response parameters. Conclusion Retinal reactivity was impaired in prediabetic and type 2 diabetic individuals in parallel with reduced insulin sensitivity but not associated with levels of hs-CRP. Retinal vasoreactivity measurements may be a sensitive tool to assess early vascular risk. PMID:23742315

  8. Retinal vascular fractals predict long-term microvascular complications in type 1 diabetes mellitus

    DEFF Research Database (Denmark)

    Broe, Rebecca; Rasmussen, Malin L; Frydkjaer-Olsen, Ulrik

    2014-01-01

    : We included 180 patients with type 1 diabetes in a 16 year follow-up study. In baseline retinal photographs (from 1995), all vessels in a zone 0.5-2.0 disc diameters from the disc margin were traced using Singapore Institute Vessel Assessment-Fractal image analysis software. Artefacts were removed......AIMS/HYPOTHESIS: Fractal analysis of the retinal vasculature provides a global measure of the complexity and density of retinal vessels summarised as a single variable: the fractal dimension. We investigated fractal dimensions as long-term predictors of microvasculopathy in type 1 diabetes. METHODS....... Retinal fractal analysis therefore is a potential tool for risk stratification in type 1 diabetes....

  9. Automatic segmentation of blood vessels from retinal fundus images ...

    Indian Academy of Sciences (India)

    The retinal blood vessels were segmented through color space conversion and color channel extraction, image pre-processing, Gabor filtering, image postprocessing, feature construction through application of principal component analysis, k-means clustering and first level classification using Naïve–Bayes classification ...

  10. A Morphological Hessian Based Approach for Retinal Blood Vessels Segmentation and Denoising Using Region Based Otsu Thresholding.

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    Khan BahadarKhan

    Full Text Available Diabetic Retinopathy (DR harm retinal blood vessels in the eye causing visual deficiency. The appearance and structure of blood vessels in retinal images play an essential part in the diagnoses of an eye sicknesses. We proposed a less computational unsupervised automated technique with promising results for detection of retinal vasculature by using morphological hessian based approach and region based Otsu thresholding. Contrast Limited Adaptive Histogram Equalization (CLAHE and morphological filters have been used for enhancement and to remove low frequency noise or geometrical objects, respectively. The hessian matrix and eigenvalues approach used has been in a modified form at two different scales to extract wide and thin vessel enhanced images separately. Otsu thresholding has been further applied in a novel way to classify vessel and non-vessel pixels from both enhanced images. Finally, postprocessing steps has been used to eliminate the unwanted region/segment, non-vessel pixels, disease abnormalities and noise, to obtain a final segmented image. The proposed technique has been analyzed on the openly accessible DRIVE (Digital Retinal Images for Vessel Extraction and STARE (STructured Analysis of the REtina databases along with the ground truth data that has been precisely marked by the experts.

  11. Automated identification of retinal vessels using a multiscale directional contrast quantification (MDCQ) strategy

    Energy Technology Data Exchange (ETDEWEB)

    Zhen, Yi; Zhang, Xinyuan; Wang, Ningli, E-mail: wningli@vip.163.com, E-mail: puj@upmc.edu [National Engineering Research Center for Ophthalmic Equipments, Beijing, 100730 (China); Gu, Suicheng; Meng, Xin [Imaging Research Center, Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, 15213 (United States); Zheng, Bin [School of Electrical and Computer Engineering, University of Oklahoma, Norman, Oklahoma 73019 (United States); Pu, Jiantao, E-mail: wningli@vip.163.com, E-mail: puj@upmc.edu [Imaging Research Center, Departments of Radiology and Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, 15213 (United States)

    2014-09-15

    Purpose: A novel algorithm is presented to automatically identify the retinal vessels depicted in color fundus photographs. Methods: The proposed algorithm quantifies the contrast of each pixel in retinal images at multiple scales and fuses the resulting consequent contrast images in a progressive manner by leveraging their spatial difference and continuity. The multiscale strategy is to deal with the variety of retinal vessels in width, intensity, resolution, and orientation; and the progressive fusion is to combine consequent images and meanwhile avoid a sudden fusion of image noise and/or artifacts in space. To quantitatively assess the performance of the algorithm, we tested it on three publicly available databases, namely, DRIVE, STARE, and HRF. The agreement between the computer results and the manual delineation in these databases were quantified by computing their overlapping in both area and length (centerline). The measures include sensitivity, specificity, and accuracy. Results: For the DRIVE database, the sensitivities in identifying vessels in area and length were around 90% and 70%, respectively, the accuracy in pixel classification was around 99%, and the precisions in terms of both area and length were around 94%. For the STARE database, the sensitivities in identifying vessels were around 90% in area and 70% in length, and the accuracy in pixel classification was around 97%. For the HRF database, the sensitivities in identifying vessels were around 92% in area and 83% in length for the healthy subgroup, around 92% in area and 75% in length for the glaucomatous subgroup, around 91% in area and 73% in length for the diabetic retinopathy subgroup. For all three subgroups, the accuracy was around 98%. Conclusions: The experimental results demonstrate that the developed algorithm is capable of identifying retinal vessels depicted in color fundus photographs in a relatively reliable manner.

  12. Fractal analysis reveals reduced complexity of retinal vessels in CADASIL.

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    Michele Cavallari

    2011-04-01

    Full Text Available The Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL affects mainly small cerebral arteries and leads to disability and dementia. The relationship between clinical expression of the disease and progression of the microvessel pathology is, however, uncertain as we lack tools for imaging brain vessels in vivo. Ophthalmoscopy is regarded as a window into the cerebral microcirculation. In this study we carried out an ophthalmoscopic examination in subjects with CADASIL. Specifically, we performed fractal analysis of digital retinal photographs. Data are expressed as mean fractal dimension (mean-D, a parameter that reflects complexity of the retinal vessel branching. Ten subjects with genetically confirmed diagnosis of CADASIL and 10 sex and age-matched control subjects were enrolled. Fractal analysis of retinal digital images was performed by means of a computer-based program, and the data expressed as mean-D. Brain MRI lesion volume in FLAIR and T1-weighted images was assessed using MIPAV software. Paired t-test was used to disclose differences in mean-D between CADASIL and control groups. Spearman rank analysis was performed to evaluate potential associations between mean-D values and both disease duration and disease severity, the latter expressed as brain MRI lesion volumes, in the subjects with CADASIL. The results showed that mean-D value of patients (1.42±0.05; mean±SD was lower than control (1.50±0.04; p = 0.002. Mean-D did not correlate with disease duration nor with MRI lesion volumes of the subjects with CADASIL. The findings suggest that fractal analysis is a sensitive tool to assess changes of retinal vessel branching, likely reflecting early brain microvessel alterations, in CADASIL patients.

  13. Supervised retinal vessel segmentation from color fundus images based on matched filtering and AdaBoost classifier.

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    Nogol Memari

    Full Text Available The structure and appearance of the blood vessel network in retinal fundus images is an essential part of diagnosing various problems associated with the eyes, such as diabetes and hypertension. In this paper, an automatic retinal vessel segmentation method utilizing matched filter techniques coupled with an AdaBoost classifier is proposed. The fundus image is enhanced using morphological operations, the contrast is increased using contrast limited adaptive histogram equalization (CLAHE method and the inhomogeneity is corrected using Retinex approach. Then, the blood vessels are enhanced using a combination of B-COSFIRE and Frangi matched filters. From this preprocessed image, different statistical features are computed on a pixel-wise basis and used in an AdaBoost classifier to extract the blood vessel network inside the image. Finally, the segmented images are postprocessed to remove the misclassified pixels and regions. The proposed method was validated using publicly accessible Digital Retinal Images for Vessel Extraction (DRIVE, Structured Analysis of the Retina (STARE and Child Heart and Health Study in England (CHASE_DB1 datasets commonly used for determining the accuracy of retinal vessel segmentation methods. The accuracy of the proposed segmentation method was comparable to other state of the art methods while being very close to the manual segmentation provided by the second human observer with an average accuracy of 0.972, 0.951 and 0.948 in DRIVE, STARE and CHASE_DB1 datasets, respectively.

  14. New algorithm for detecting smaller retinal blood vessels in fundus images

    Science.gov (United States)

    LeAnder, Robert; Bidari, Praveen I.; Mohammed, Tauseef A.; Das, Moumita; Umbaugh, Scott E.

    2010-03-01

    About 4.1 million Americans suffer from diabetic retinopathy. To help automatically diagnose various stages of the disease, a new blood-vessel-segmentation algorithm based on spatial high-pass filtering was developed to automatically segment blood vessels, including the smaller ones, with low noise. Methods: Image database: Forty, 584 x 565-pixel images were collected from the DRIVE image database. Preprocessing: Green-band extraction was used to obtain better contrast, which facilitated better visualization of retinal blood vessels. A spatial highpass filter of mask-size 11 was applied. A histogram stretch was performed to enhance contrast. A median filter was applied to mitigate noise. At this point, the gray-scale image was converted to a binary image using a binary thresholding operation. Then, a NOT operation was performed by gray-level value inversion between 0 and 255. Postprocessing: The resulting image was AND-ed with its corresponding ring mask to remove the outer-ring (lens-edge) artifact. At this point, the above algorithm steps had extracted most of the major and minor vessels, with some intersections and bifurcations missing. Vessel segments were reintegrated using the Hough transform. Results: After applying the Hough transform, both the average peak SNR and the RMS error improved by 10%. Pratt's Figure of Merit (PFM) was decreased by 6%. Those averages were better than [1] by 10-30%. Conclusions: The new algorithm successfully preserved the details of smaller blood vessels and should prove successful as a segmentation step for automatically identifying diseases that affect retinal blood vessels.

  15. A multi-scale tensor voting approach for small retinal vessel segmentation in high resolution fundus images.

    Science.gov (United States)

    Christodoulidis, Argyrios; Hurtut, Thomas; Tahar, Houssem Ben; Cheriet, Farida

    2016-09-01

    Segmenting the retinal vessels from fundus images is a prerequisite for many CAD systems for the automatic detection of diabetic retinopathy lesions. So far, research efforts have concentrated mainly on the accurate localization of the large to medium diameter vessels. However, failure to detect the smallest vessels at the segmentation step can lead to false positive lesion detection counts in a subsequent lesion analysis stage. In this study, a new hybrid method for the segmentation of the smallest vessels is proposed. Line detection and perceptual organization techniques are combined in a multi-scale scheme. Small vessels are reconstructed from the perceptual-based approach via tracking and pixel painting. The segmentation was validated in a high resolution fundus image database including healthy and diabetic subjects using pixel-based as well as perceptual-based measures. The proposed method achieves 85.06% sensitivity rate, while the original multi-scale line detection method achieves 81.06% sensitivity rate for the corresponding images (p<0.05). The improvement in the sensitivity rate for the database is 6.47% when only the smallest vessels are considered (p<0.05). For the perceptual-based measure, the proposed method improves the detection of the vasculature by 7.8% against the original multi-scale line detection method (p<0.05). Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Associations of blood pressure variability and retinal arteriolar diameter in participants with type 2 diabetes.

    Science.gov (United States)

    Veloudi, Panagiota; Blizzard, Leigh; Srikanth, Velandai K; McCartney, Paul; Lukoshkova, Elena V; Hughes, Alun D; Head, Geoffrey A; Sharman, James E

    2016-07-01

    Blood pressure variability is associated with macrovascular complications and stroke, but its association with the microcirculation in type II diabetes has not been assessed. This study aimed to determine the relationship between blood pressure variability indices and retinal arteriolar diameter in non-diabetic and type II diabetes participants. Digitized retinal images were analysed to quantify arteriolar diameters in 35 non-diabetic (aged 52 ± 11 years; 49% male) and 28 type II diabetes (aged 61 ± 9 years; 50% male) participants. Blood pressure variability was derived from 24-h ambulatory blood pressure. Arteriolar diameter was positively associated with daytime rate of systolic blood pressure variation (p = 0.04) among type II diabetes participants and negatively among non-diabetics (p = 0.008; interaction p = 0.001). This finding was maintained after adjusting for age, sex, body mass index and mean daytime systolic blood pressure. These findings suggest that the blood pressure variability-related mechanisms underlying retinal vascular disease may differ between people with and without type II diabetes. © The Author(s) 2016.

  17. Vessel diameter measurements in gadolinium contrast-enhanced three-dimensional MRA of peripheral arteries

    NARCIS (Netherlands)

    Westenberg, J.J.M.; Geest, van der R.J.; Wasser, M.N.J.M.; Linden, van der E.L.; Walsum, van T.; Assen, van H.C.; Roos, de A.; Vanderschoot, J.; Reiber, J.H.C.

    2000-01-01

    In this study, the possibilities for quantification of vessel diameters of peripheral arteries in gadolinium contrast-enhanced magnetic resonance angiography (Gd CE MRA) were evaluated. Absolute vessel diameter measurements were assessed objectively and semi-automatically in maximum intensity

  18. Retinal Vessel Segmentation Based on Primal-Dual Asynchronous Particle Swarm Optimisation (pdAPSO Algorithm

    Directory of Open Access Journals (Sweden)

    E. G. Dada

    2017-04-01

    Full Text Available Acute damage to the retina vessel has been identified to be main reason for blindness and impaired vision all over the world. A timely detection and control of these illnesses can greatly decrease the number of loss of sight cases. Developing a high performance unsupervised retinal vessel segmentation technique poses an uphill task. This paper presents study on the Primal-Dual Asynchronous Particle Swarm Optimisation (pdAPSO method for the segmentation of retinal vessels. A maximum average accuracy rate 0.9243 with an average specificity of sensitivity rate of 0.9834 and average sensitivity rate of 0.5721 were achieved on DRIVE database. The proposed method produces higher mean sensitivity and accuracy rates in the same range of very good specificity.

  19. Retinal arterioles narrow with increasing duration of anti-retroviral therapy in HIV infection: a novel estimator of vascular risk in HIV?

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    Sophia Pathai

    Full Text Available HIV infection is associated with an increased risk of age-related morbidity mediated by immune dysfunction, atherosclerosis and inflammation. Changes in retinal vessel calibre may reflect cumulative structural damage arising from these mechanisms. The relationship of retinal vessel calibre with clinical and demographic characteristics was investigated in a population of HIV-infected individuals in South Africa.Case-control study of 491 adults ≥30 years, composed of 242 HIV-infected adults and 249 age- and gender-matched HIV-negative controls. Retinal vessel calibre was measured using computer-assisted techniques to determine mean arteriolar and venular diameters of each eye.The median age was 40 years (IQR: 35-48 years. Among HIV-infected adults, 87.1% were receiving highly active antiretroviral therapy (HAART (median duration, 58 months, their median CD4 count was 468 cells/µL, and 84.3% had undetectable plasma viral load. Unadjusted mean retinal arteriolar diameters were 163.67±17.69 µm in cases and 161.34±17.38 µm in controls (p = 0.15. Unadjusted mean venular diameters were 267.77±18.21 µm in cases and 270.81±18.98 µm in controls (p = 0.07. Age modified the effect of retinal arteriolar and venular diameters in relation to HIV status, with a tendency towards narrower retinal diameters in HIV cases but not in controls. Among cases, retinal arteriolar diameters narrowed with increasing duration of HAART, independently of age (167.83 µm 6 years, p-trend = 0.02, and with a HIV viral load >10,000 copies/mL while on HAART (p = 0.05. HIV-related venular changes were not detected.Narrowing of retinal arteriolar diameters is associated with HAART duration and viral load, and may reflect heightened inflammatory and pro-atherogenic states of the systemic vasculature. Measurement of retinal vascular calibre could be an innovative non-invasive method of estimating vascular risk in HIV-infected individuals.

  20. Knockdown of Zebrafish Blood Vessel Epicardial Substance Results in Incomplete Retinal Lamination

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    Yu-Ching Wu

    2014-01-01

    Full Text Available Cell polarity during eye development determines the normal retinal lamination and differentiation of photoreceptor cells in the retina. In vertebrates, blood vessel epicardial substance (Bves is known to play an important role in the formation and maintenance of the tight junctions essential for epithelial cell polarity. In the current study, we generated a transgenic zebrafish Bves (zbves promoter-EGFP zebrafish line to investigate the expression pattern of Bves in the retina and to study the role of zbves in retinal lamination. Immunostaining with different specific antibodies from retinal cells and transmission electron microscopy were used to identify the morphological defects in normal and Bves knockdown zebrafish. In normal zebrafish, Bves is located at the apical junctions of embryonic retinal neuroepithelia during retinogenesis; later, it is strongly expressed around inner plexiform layer (IPL and retinal pigment epithelium (RPE. In contrast, a loss of normal retinal lamination and cellular polarity was found with undifferentiated photoreceptor cells in Bves knockdown zebrafish. Herein, our results indicated that disruption of Bves will result in a loss of normal retinal lamination.

  1. Summarising the retinal vascular calibres in healthy, diabetic and diabetic retinopathy eyes.

    Science.gov (United States)

    Leontidis, Georgios; Al-Diri, Bashir; Hunter, Andrew

    2016-05-01

    Retinal vessel calibre has been found to be an important biomarker of several retinal diseases, including diabetic retinopathy (DR). Quantifying the retinal vessel calibres is an important step for estimating the central retinal artery and vein equivalents. In this study, an alternative method to the already established branching coefficient (BC) is proposed for summarising the vessel calibres in retinal junctions. This new method combines the mean diameter ratio with an alternative to Murray׳s cube law exponent, derived by the fractal dimension,experimentally, and the branch exponent of cerebral vessels, as has been suggested in previous studies with blood flow modelling. For the above calculations, retinal images from healthy, diabetic and DR subjects were used. In addition, the above method was compared with the BC and was also applied to the evaluation of arteriovenous ratio as a biomarker of progression from diabetes to DR in four consecutive years, i.e. three/two/one years before the onset of DR and the first year of DR. Moreover, the retinal arteries and veins around the optic nerve head were also evaluated. The new approach quantifies the vessels more accurately. The decrease in terms of the mean absolute percentage error was between 0.24% and 0.49%, extending at the same time the quantification beyond healthy subjects. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Retinal Vessel Segmentation via Structure Tensor Coloring and Anisotropy Enhancement

    Directory of Open Access Journals (Sweden)

    Mehmet Nergiz

    2017-11-01

    Full Text Available Retinal vessel segmentation is one of the preliminary tasks for developing diagnosis software systems related to various retinal diseases. In this study, a fully automated vessel segmentation system is proposed. Firstly, the vessels are enhanced using a Frangi Filter. Afterwards, Structure Tensor is applied to the response of the Frangi Filter and a 4-D tensor field is obtained. After decomposing the Eigenvalues of the tensor field, the anisotropy between the principal Eigenvalues are enhanced exponentially. Furthermore, this 4-D tensor field is converted to the 3-D space which is composed of energy, anisotropy and orientation and then a Contrast Limited Adaptive Histogram Equalization algorithm is applied to the energy space. Later, the obtained energy space is multiplied by the enhanced mean surface curvature of itself and the modified 3-D space is converted back to the 4-D tensor field. Lastly, the vessel segmentation is performed by using Otsu algorithm and tensor coloring method which is inspired by the ellipsoid tensor visualization technique. Finally, some post-processing techniques are applied to the segmentation result. In this study, the proposed method achieved mean sensitivity of 0.8123, 0.8126, 0.7246 and mean specificity of 0.9342, 0.9442, 0.9453 as well as mean accuracy of 0.9183, 0.9442, 0.9236 for DRIVE, STARE and CHASE_DB1 datasets, respectively. The mean execution time of this study is 6.104, 6.4525 and 18.8370 s for the aforementioned three datasets respectively.

  3. A confocal scanning laser ophthalmoscope for retinal vessel oximetry

    Science.gov (United States)

    Lompado, Arthur

    Measurement of a person's blood oxygen saturation has long been recognized as a useful metric for the characterizing ailments ranging from chronic respiratory disorders to acute, potentially life threatening, traumas. The ubiquity of oxygen saturation monitors in the medical field, including portable pulse oximeters and laboratory based CO-oximeters, is a testament to the importance of this technique. The work presented here documents the design, fabrication and development of a unique type of oxygen saturation monitor, a confocal scanning retinal vessel oximeter, with the potential to expand the usefulness of the present devices. A large part of the knowledge base required to construct the instrument comes from the consideration of light scattering by red blood cells in a blood vessel. Therefore, a substantial portion of this work is devoted to the process of light scattering by whole human blood and its effects on the development of a more accurate oximeter. This light scattering effect has been both measured and modeled stochastically to determine its contribution to the measured oximeter signal. It is shown that, although well accepted in the published literature, the model only correlates marginally to the measurements due to inherent limitations imposed by the model assumptions. Nonetheless, enough material has been learned about the scattering to allow development of a mathematical model for the interaction of light with blood in a vessel, and this knowledge has been applied to the data reduction of the present oximeter. This data reduction technique has been tested in a controlled experiment employing a model eye with a blood filled mock retinal vessel. It will be shown that the presently developed technique exhibited strong correlation between the known blood oxygen saturation and that calculated by the new system.

  4. Retinal changes in diabetic patients without diabetic retinopathy.

    Science.gov (United States)

    Dumitrescu, Alina Gabriela; Istrate, Sinziana Luminita; Iancu, Raluca Claudia; Guta, Oana Maria; Ciuluvica, Radu; Voinea, Liliana

    2017-01-01

    The purpose of this study was to measure retinal vessel caliber and to examine early changes in macular thickness using optical coherence tomography (OCT). We evaluated to what extend vascular caliber and macular thickness differed between patients with type 2 diabetes mellitus without diabetic retinopathy compared with healthy individuals. 26 diabetic patients without diabetic retinopathy and 26 normal participants without any retinal and optic nerve diseases underwent ophthalmic examination, fundus photography, and OCT imaging. Temporal inferior retinal vessel diameters were measured using OCT. Also, we measured macular thickness in nine ETDRS subfields using Cirrus OCT. The mean age in the diabetic group was 61.5 years and in the control group, 55.5 years. Wider retinal arterioles and venules were found in patients with diabetes compared with healthy subjects (120 µm versus 96 µm, pdiabetes mellitus, central macular thickness was significantly thinner than that of control eyes (243.5 µm versus 269.9 µm, p value diabetes without diabetic retinopathy.

  5. Lack of differences in the regional variation of oxygen saturation in larger retinal vessels in diabetic maculopathy and proliferative diabetic retinopathy.

    Science.gov (United States)

    Jørgensen, Christina Mørup; Bek, Toke

    2017-06-01

    Diabetic retinopathy is characterised by morphological lesions in the ocular fundus related to disturbances in retinal blood flow. The two vision threatening forms of retinopathy show specific patterns of distribution of retinal lesions with proliferative diabetic retinopathy (PDR) developing secondary to ischaemia and hypoxia in the retinal periphery and diabetic maculopathy (DM) developing secondary to hyperperfusion and increased vascular permeability in the macular area. These differences in the distribution of retinal lesions might be reflected in regional differences in oxygen saturation in the larger retinal vessels. Dual-wavelength retinal oximetry was performed in 30 normal persons, 30 patients with DM and 30 patients with PDR, and the oxygen saturation was measured in peripapillary vessels supplying the four retinal quadrants and in branches from the upper temporal arcades supplying, respectively, the macular area and the retinal periphery. The overall oxygen saturation was significantly higher in diabetic patients than in normal persons and the arteriovenous (AV) saturation difference significantly lower in the patients with DM. The regional variation in oxygen saturation was similar in the three studied groups with a decreasing saturation from the upper nasal through the lower nasal, lower temporal and the upper temporal peripapillary vessels, and with a significantly higher oxygen saturation in venules draining the macular area than in venules draining the retinal periphery. The regional differences in retinal lesions in vision threatening diabetic retinopathy are not reflected in regional differences in the oxygen saturation of larger retinal vessels. The development of vision threatening diabetic retinopathy depends on other factors, such as, for example, regional differences in the retinal microcirculation. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  6. Estimation of center line and diameter of brain blood vessel using three-dimensional blood vessel matching method with head three-dimensional CTA image

    International Nuclear Information System (INIS)

    Maekawa, Masashi; Shinohara, Toshihiro; Nakayama, Masato; Nakasako, Noboru

    2010-01-01

    To support and automate the brain blood vessel disease diagnosis, a novel method to obtain the center line and the diameter of a blood vessel is proposed with a three-dimensional head computed tomographic angiography (CTA) image. Although the line thinning processing with distance transform or gray information is generally used to obtain the blood vessel center line, this method is not essentially one to obtain the center line and tends to yield extra lines depending on CTA images. In this study, the center line of the blood vessel is obtained by tracing the vessel. The blood vessel is traced by sequentially estimating the center point and direction of the blood vessel. The center point and direction of the blood vessel are estimated by taking the correlation between the blood vessel and a solid model of the blood vessel that is designed by considering noise influence. In addition, the vessel diameter is also estimated by correlating the blood vessel and the blood vessel model of which the diameter is variable. The validity of the proposed method is confirmed by experimentally applied the proposed method to an actual three-dimensional head CTA image. (author)

  7. Novel algorithm by low complexity filter on retinal vessel segmentation

    Science.gov (United States)

    Rostampour, Samad

    2011-10-01

    This article shows a new method to detect blood vessels in the retina by digital images. Retinal vessel segmentation is important for detection of side effect of diabetic disease, because diabetes can form new capillaries which are very brittle. The research has been done in two phases: preprocessing and processing. Preprocessing phase consists to apply a new filter that produces a suitable output. It shows vessels in dark color on white background and make a good difference between vessels and background. The complexity is very low and extra images are eliminated. The second phase is processing and used the method is called Bayesian. It is a built-in in supervision classification method. This method uses of mean and variance of intensity of pixels for calculate of probability. Finally Pixels of image are divided into two classes: vessels and background. Used images are related to the DRIVE database. After performing this operation, the calculation gives 95 percent of efficiency average. The method also was performed from an external sample DRIVE database which has retinopathy, and perfect result was obtained

  8. Retinal vessel caliber as a potential marker of treatment outcome in patients with proliferative diabetic retinopathy

    DEFF Research Database (Denmark)

    Vergmann, Anna Stage; Torp, Thomas Lee; Lundberg, Kristian

    Title of abstract: Retinal vessel caliber as a potential marker of treatment outcome in patients with proliferative diabetic retinopathy Design of study: Three months prospective, interventional clinical study. Purpose: The retinal vascular tree can be measured non-invasively and summarized...... into the central retinal artery and vein equivalent (CRAE and CRVE). The purpose of this study was to evaluate retinal calibers as biomarkers for disease activity 3 months after panretinal photocoagulation (PRP) in patients with proliferative diabetic retinopathy (PDR). Methods: Fifty one eyes from 40 newly...... with proliferative diabetic retinopathy....

  9. Localized changes in Retinal Vessel Caliber after focal/grid laser treatment in Patients with Diabetic Macular Edema

    DEFF Research Database (Denmark)

    Lundberg, Lars Kristian; Kawasaki, Ryo; Sjølie, Anne K

    2013-01-01

    PURPOSE:: To compare retinal vessel caliber changes at the macula region and surrounding the optic disk after focal/grid laser treatment for diabetic macular edema. METHODS:: The study included 69 eyes from 46 patients treated with focal/grid laser for diabetic macular edema. Retinal photographs...

  10. Relationship between retinal blood flow and arterial oxygen.

    Science.gov (United States)

    Cheng, Richard W; Yusof, Firdaus; Tsui, Edmund; Jong, Monica; Duffin, James; Flanagan, John G; Fisher, Joseph A; Hudson, Chris

    2016-02-01

    Vascular reactivity, the response of the vessels to a vasoactive stimulus such as hypoxia and hyperoxia, can be used to assess the vascular range of adjustment in which the vessels are able to compensate for changes in PO2. Previous studies in the retina have not accurately quantified retinal vascular responses and precisely targeted multiple PaO2 stimuli at the same time as controlling the level of carbon dioxide, thus precluding them from modelling the relationship between retinal blood flow and oxygen. The present study modelled the relationship between retinal blood flow and PaO2, showing them to be a combined linear and hyperbolic function. This model demonstrates that the resting tonus of the vessels is at the mid-point and that they have great vascular range of adjustment, compensating for decreases in oxygen above a PETCO2 of 32-37 mmHg but being limited below this threshold. Retinal blood flow (RBF) increases in response to a reduction in oxygen (hypoxia) but decreases in response to increased oxygen (hyperoxia). However, the relationship between blood flow and the arterial partial pressure of oxygen has not been quantified and modelled in the retina, particularly in the vascular reserve and resting tonus of the vessels. The present study aimed to determine the limitations of the retinal vasculature by modelling the relationship between RBF and oxygen. Retinal vascular responses were measured in 13 subjects for eight different blood gas conditions, with the end-tidal partial pressure of oxygen (PETCO2) ranging from 40-500 mmHg. Retinal vascular response measurements were repeated twice; using the Canon laser blood flowmeter (Canon Inc., Tokyo, Japan) during the first visit and using Doppler spectral domain optical coherence tomography during the second visit. We determined that the relationship between RBF and PaO2 can be modelled as a combination of hyperbolic and linear functions. We concluded that RBF compensated for decreases in arterial oxygen content

  11. Differential diagnosis of retinal vasculitis.

    Science.gov (United States)

    Abu El-Asrar, Ahmed M; Herbort, Carl P; Tabbara, Khalid F

    2009-10-01

    Retinal vaculitis is a sight-threatening inflammatory eye condition that involves the retinal vessels. Detection of retinal vasculitis is made clinically, and confirmed with the help of fundus fluorescein angiography. Active vascular disease is characterized by exudates around retinal vessels resulting in white sheathing or cuffing of the affected vessels. In this review, a practical approach to the diagnosis of retinal vasculitis is discussed based on ophthalmoscopic and fundus fluorescein angiographic findings.

  12. Retinal displacement toward optic disc after internal limiting membrane peeling for idiopathic macular hole.

    Science.gov (United States)

    Ishida, Masahiro; Ichikawa, Yoshikazu; Higashida, Rieko; Tsutsumi, Yorihisa; Ishikawa, Atsushi; Imamura, Yutaka

    2014-05-01

    To examine the retinal displacement following successful macular hole (MH) surgery with internal limiting membrane (ILM) peeling and gas tamponade, and to determine the correlation between the extent of displacement and the basal MH size. Retrospective, interventional, observational case series. The medical records of consecutive patients with an idiopathic MH that had undergone vitrectomy with ILM peeling and gas tamponade were studied. The distances between the optic disc and the intersection of 2 retinal vessels located nasal or temporal to the fovea were measured manually preoperatively (A), and 2 weeks and 1, 3, 6, and 12 months postoperatively (B), on the fundus autofluorescence or near-infrared images. The basal and minimum diameters of the MHs were measured in the spectral-domain optical coherence tomographic images. The correlations between the ratio of the retinal displacement (A - B/A) and basal diameters of the MHs were determined. Twenty-one eyes of 21 patients (9 men, mean age: 64.6 ± 8.4 years) were studied. Ten eyes (47.6%) had stage 2 MH, 9 eyes (42.9%) had stage 3 MH, and 2 eyes (9.5%) had stage 4 MH. The temporal retinal vessels were displaced 260.8 ± 145.8 μm toward the optic disc at 2 weeks postoperatively, which was significantly greater than the 91.1 ± 89.7 μm of the nasal retinal vessels (paired t test, P displacement in the temporal field at 2 weeks was significantly correlated with the basal diameter of the MH (Spearman's rank correlation coeffieient = -0.476, P = .033. The greater displacement of the temporal retina than the nasal retina toward the optic disc postoperatively suggests that the temporal retina is more flexible and can be retracted toward the optic disc during the MH closure. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Automated detection of kinks from blood vessels for optic cup segmentation in retinal images

    Science.gov (United States)

    Wong, D. W. K.; Liu, J.; Lim, J. H.; Li, H.; Wong, T. Y.

    2009-02-01

    The accurate localization of the optic cup in retinal images is important to assess the cup to disc ratio (CDR) for glaucoma screening and management. Glaucoma is physiologically assessed by the increased excavation of the optic cup within the optic nerve head, also known as the optic disc. The CDR is thus an important indicator of risk and severity of glaucoma. In this paper, we propose a method of determining the cup boundary using non-stereographic retinal images by the automatic detection of a morphological feature within the optic disc known as kinks. Kinks are defined as the bendings of small vessels as they traverse from the disc to the cup, providing physiological validation for the cup boundary. To detect kinks, localized patches are first generated from a preliminary cup boundary obtained via level set. Features obtained using edge detection and wavelet transform are combined using a statistical approach rule to identify likely vessel edges. The kinks are then obtained automatically by analyzing the detected vessel edges for angular changes, and these kinks are subsequently used to obtain the cup boundary. A set of retinal images from the Singapore Eye Research Institute was obtained to assess the performance of the method, with each image being clinically graded for the CDR. From experiments, when kinks were used, the error on the CDR was reduced to less than 0.1 CDR units relative to the clinical CDR, which is within the intra-observer variability of 0.2 CDR units.

  14. Retinal vessel caliber and myopic retinopathy: the blue mountains eye study.

    Science.gov (United States)

    Li, Haitao; Mitchell, Paul; Rochtchina, Elena; Burlutsky, George; Wong, Tien Y; Wang, Jie Jin

    2011-12-01

    To evaluate changes in the retinal vasculature in eyes with myopic retinopathy. Population-based, cross-sectional study. Emmetropic and myopic participants from the Blue Mountains Eye Study baseline survey were included in this study. Myopia was defined as a refractive error of less than -1.00 diopter. Myopic retinopathy was defined if either staphyloma, lacquer crack, Fuchs' spot or chorioretinal atrophy were present in myopic eyes. Retinal vascular caliber was measured from fundus photographs using standardized methods. The association of retinal vascular caliber with myopic retinopathy was assessed using generalized estimating equation models. A total of 2598 eyes of 1409 subjects were selected from 3654 baseline participants, with 2076 emmetropic eyes (normal controls), 486 myopic eyes without myopic retinopathy (myopic controls) and 36 myopic eyes with myopic retinopathy (cases). After adjusting for age, gender, height, body mass index and blood pressure, eyes with myopic retinopathy had significantly narrower mean arteriolar (166.6μm) and venular caliber (213.3μm), compared to normal (188.1μm and 226.9μm, respectively) or myopic control eyes (190.4μm and 227.0μm, respectively) (all P retinopathy and the two control groups remained significant after additional adjustment for refraction (all P retinopathy is associated with attenuation of retinal vessels.

  15. THE SECOND BLIND SPOT: SMALL RETINAL VESSEL VASCULOPATHY AFTER VACCINATION AGAINST NEISSERIA MENINGITIDIS AND YELLOW FEVER.

    Science.gov (United States)

    Moysidis, Stavros N; Koulisis, Nicole; Patel, Vivek R; Kashani, Amir H; Rao, Narsing A; Humayun, Mark S; Rodger, Damien C

    2017-01-01

    To describe a case of small retinal vessel vasculopathy postvaccination. We report the case of a 41-year-old white man who presented with a "second blind spot," describing a nasal scotoma in the right eye that started 4 days after vaccinations against Neisseria meningitidis and the yellow fever virus, and after a 2-month period of high stress and decreased sleep. Clinical examination, Humphrey visual field testing, and multimodal imaging with fundus photographs, autofluorescence, fluorescein angiography, and spectral domain optical coherence tomography and angiography were performed. Clinical examination revealed a well-circumscribed, triangular area of retinal graying of about 1-disk diameter in size, located at the border of the temporal macula. This corresponded to a deep scotoma similar in size to the physiologic blind spot on Humphrey visual field 24-2 testing. There was mild hypoautofluoresence of this lesion on autofluorescence, hypofluorescence on fluorescein angiography, and focal attenuation of a small artery just distal to the bifurcation of an artery supplying the involved area. Spectral domain optical coherence tomography through the lesion conveyed hyperreflectivity most prominent in the inner and outer plexiform layers, with extension of the hyperreflectivity into the ganglion cell and inner nuclear layers. Spectral domain optical coherence tomography angiography demonstrated arteriolar and capillary dropout, more pronounced in the superficial retinal layer compared to the deeper retinal layer. At 1-month follow-up, his scotoma improved with monitoring, with reduction from -32 dB to -7 dB on Humphrey visual field testing. There was clinical resolution of the area of graying and decreased hyperreflectivity on spectral domain optical coherence tomography, with atrophy of the inner retina. Spectral domain optical coherence tomography angiography showed progression of arteriolar and capillary dropout, more so in the superficial than in the deep capillary

  16. Dependence of light scattering profile in tissue on blood vessel diameter and distribution: a computer simulation study.

    Science.gov (United States)

    Duadi, Hamootal; Fixler, Dror; Popovtzer, Rachela

    2013-11-01

    Most methods for measuring light-tissue interactions focus on the volume reflectance while very few measure the transmission. We investigate both diffusion reflection and diffuse transmission at all exit angles to receive the full scattering profile. We also investigate the influence of blood vessel diameter on the scattering profile of a circular tissue. The photon propagation path at a wavelength of 850 nm is calculated from the absorption and scattering constants via Monte Carlo simulation. Several simulations are performed where a different vessel diameter and location were chosen but the blood volume was kept constant. The fraction of photons exiting the tissue at several central angles is presented for each vessel diameter. The main result is that there is a central angle that below which the photon transmission decreased for lower vessel diameters while above this angle the opposite occurred. We find this central angle to be 135 deg for a two-dimensional 10-mm diameter circular tissue cross-section containing blood vessels. These findings can be useful for monitoring blood perfusion and oxygen delivery in the ear lobe and pinched tissues. © 2013 Society of Photo-Optical Instrumentation Engineers (SPIE)

  17. Automatic evaluation of vessel diameter variation from 2D X-ray angiography.

    Science.gov (United States)

    M'hiri, Faten; Duong, Luc; Desrosiers, Christian; Dahdah, Nagib; Miró, Joaquim; Cheriet, Mohamed

    2017-11-01

    Early detection of blood vessel pathologies can be made through the evaluation of functional and structural abnormalities in the arteries, including the arterial distensibility measure. We propose a feasibility study on computing arterial distensibility automatically from monoplane 2D X-ray sequences for both small arteries (such as coronary arteries) and larger arteries (such as the aorta). To compute the distensibility measure, three steps were developed: First, the segment of an artery is extracted using our graph-based segmentation method. Then, the same segment is tracked in the moving sequence using our spatio-temporal segmentation method: the Temporal Vessel Walker. Finally, the diameter of the artery is measured automatically at each frame of the sequence based on the segmentation results. The method was evaluated using one simulated sequence and 4 patients' angiograms depicting the coronary arteries and three depicting the ascending aorta. Results of the simulated sequence achieved a Dice index of 98%, with a mean squared error in diameter measurement of [Formula: see text] mm. Results obtained from patients' X-ray sequences are consistent with manual assessment of the diameter by experts. The proposed method measures changes in diameter of a specific segment of a blood vessel during the cardiac sequence, automatically based on monoplane 2D X-ray sequence. Such information might become a key to help physicians in the detection of variations of arterial stiffness associated with early stages of various vasculopathies.

  18. Influencing factors affecting the retinal blood vessel morphology in patients with diabetes mellitus

    Directory of Open Access Journals (Sweden)

    Xiao-Lu Kong

    2017-03-01

    Full Text Available AIM: To analyze the influencing factors affecting retinal blood vessel morphology in patients with diabetes mellitus. METHODS: Totally 312 patients with type 2 diabetes mellitus in our hospital from January 2012 to September 2016 were selected as study subjects. The patients were examined by fundus photography and related laboratory. As grouping factors in the patients'age, sex, disease duration, smoking, drinking, hypertension, hyperlipidemia or diabetic nephropathy, we compared the incidence of retinal vascular changes in different groups. The meaningful factors were introduced into the Logistic regression equation again. Independent risk factors for retinal vascular changes in patients with diabetes mellitus were screened out. RESULTS:In 312 cases of patients with type 2 diabetes mellitus,169 cases were accompanied with retinal vascular abnormalities, and 143 cases were not associated with retinal vascular abnormalities. Univariate analysis showed that age, duration of disease, hypertension, hyperlipidemia or diabetes nephropathy were significantly correlated with retinal vascular morphological changes(PP>0.05. Retinal vascular abnormalities were used as the dependent variable, and the above mentioned factors were grouped as independent variables. By Logistic stepwise regression analysis showed that the course of disease, patients with hypertension or diabetic nephropathy were the independent risk factors of abnormal retinal vascular morphology(PCONCLUSION: The independent risk factors for the occurrence of retinal vascular changes in patients with diabetes mellitus are increased course of disease, hypertension or diabetic nephropathy. Early diagnosis and intervention, to take measures and control blood pressure, reduce kidney damage can reduce the incidence of diabetic retinopathy, and macrovascular disease caused by diabetes, the incidence of adverse cardiovascular and cerebrovascular events.

  19. Segmentation of retinal blood vessels using artificial neural networks for early detection of diabetic retinopathy

    Science.gov (United States)

    Mann, Kulwinder S.; Kaur, Sukhpreet

    2017-06-01

    There are various eye diseases in the patients suffering from the diabetes which includes Diabetic Retinopathy, Glaucoma, Hypertension etc. These all are the most common sight threatening eye diseases due to the changes in the blood vessel structure. The proposed method using supervised methods concluded that the segmentation of the retinal blood vessels can be performed accurately using neural networks training. It uses features which include Gray level features; Moment Invariant based features, Gabor filtering, Intensity feature, Vesselness feature for feature vector computation. Then the feature vector is calculated using only the prominent features.

  20. Aging decreases CO2 reactivity in the retinal artery, but not in the ocular choroidal vessels; a cross-sectional study.

    Science.gov (United States)

    Miyaji, Akane; Ikemura, Tsukasa; Hayashi, Naoyuki

    2018-04-14

    The CO2 reactivity is often used to assess vascular function, but it is still unclear whether this reactivity is affected by aging. To investigate the effects of aging on the CO2 reactivity in ocular and cerebral vessels, both of which are highly sensitive to hypercapnia, we compared the CO2 reactivity in the retinal artery (RA), retinal and choroidal vessels (RCV), optic nerve head (ONH), and middle cerebral artery (MCA) between young and middle-aged subjects. We measured the CO2 reactivity in 14 young and 11 middle-aged males using laser-speckle flowgraphy during a 3-min inhalation of CO2-rich air. The CO2 reactivity in the RA and ONH were lower in the middle-aged group than in the young group, but no significant effect of age was observed in the RCV or MCA. The CO2 reactivity in the RA and ONH were correlated significantly with age, whereas those in the RCV or MCA were not. These findings suggest that there are regional differences in the effect of age on the CO2 reactivity among not only ocular and cerebral vessels, but also the retinal and choroidal vessels, even though these vessels are in neighboring areas.

  1. Middle Cerebral Artery, Ophthalmic Artery, and Multibranch Retinal Vessel Occlusion After Cosmetic Autologous Fat Transfer to Forehead.

    Science.gov (United States)

    Roshandel, Danial; Soheilian, Masoud; Pakravan, Mohammad; Aghayan, Sara; Peyman, Gholam A

    2015-05-01

    A 65-year-old woman with left hemiparesis and sudden loss of visual acuity in her right eye presented a few hours after cosmetic injection of autologous fat to her forehead. Right eye visual acuity was no light perception. Funduscopy revealed widespread retinal whitening and multibranch retinal vessel occlusion. Fluorescein angiography showed markedly delayed choroidal and retinal filling together with occlusion of multiple branches of retinal arteries and veins. On magnetic resonance imaging of the brain, multiple lesions compatible with recent infarction were detected. The authors diagnosed multibranch retinal artery and vein occlusion in the right ophthalmic and middle cerebral arteries due to fat emboli. This case emphasizes the need to reevaluate the safety of such aesthetic procedures, particularly in the facial zone to prevent devastating complications. Copyright 2015, SLACK Incorporated.

  2. Flow patterns on spectral-domain optical coherence tomography reveal flow directions at retinal vessel bifurcations

    DEFF Research Database (Denmark)

    Willerslev, Anne; Li, Xiao Q; Munch, Inger C

    2014-01-01

    PURPOSE: To study intravascular characteristics of flowing blood in retinal vessels using spectral-domain optical coherence tomography (SD-OCT). METHODS: Examination of selected arterial bifurcations and venous sites of confluence in 25 healthy 11-year-old children recruited as an ad hoc subsample...

  3. Thickening of inner retinal layers in the parafovea after bariatric surgery in patients with type 2 diabetes

    DEFF Research Database (Denmark)

    Brynskov, Troels; Laugesen, Caroline S; Floyd, Andrea K

    2016-01-01

    . METHODS: We examined 51 patients with T2D 2 weeks before and 1, 3, 6 and 12 months after bariatric surgery. Retinal thickness was measured with optical coherence tomography and automated segmentation in the fovea, parafovea and perifovea in each retinal layer. Retinal vessels were semiautomatically...... measured in a zone 0.5-1 disc diameters from the optic disc. RESULTS: The total macula thickened with a peak after 6 months in both univariate (2.7 ± 0.4 μm, p

  4. Straight versus tortuous retinal arteries in relation to blood pressure and genetics

    DEFF Research Database (Denmark)

    Taarnhøj, N C B B; Munch, I C; Sander, B

    2008-01-01

    dizygotic same-sex healthy twin pairs, aged 20 to 46 years, who were characterised by determination of retinal vessel diameters, arterial blood pressure, blood glucose, body mass index, smoking habits and retinal arterial tortuosity, using a three-level grading scale (straight, wavy, tortuous). Heritability......BACKGROUND/AIMS: To assess the relative influence of genetic and environmental factors on retinal arterial tortuosity and the association between tortuosity and various health indices in healthy young to middle-aged persons. METHODS: This cross-sectional study included 57 monozygotic and 52...... accounting for the remaining 18% (CI(95 )8, 36%). Increasing values of mean arterial blood pressure and body mass index were both associated with decreasing levels of retinal arterial tortuosity. CONCLUSION: There was a large variation in tortuosity of retinal arteries in these healthy subjects...

  5. The design of lifting attachments for the erection of large diameter and heavy wall pressure vessels

    International Nuclear Information System (INIS)

    Antalffy, Leslie P.; Miller, George A.; Kirkpatrick, Kenneth D.; Rajguru, Anil; Zhu, Yong

    2016-01-01

    Lifting attachments for the erection of large diameter and heavy wall pressure vessels require special consideration to ensure that their attachment to their vessel shells or heads do not overstress the vessel during the erection process when lifting these from grade onto their respective foundations. Today, in refinery and petrochemical services, large diameter vessels with diameters ranging up to 15 m and reactors with lifting weights in the range of 700–1400 tons are not uncommon. In today's fabrication market, these vessels may be purchased and fabricated in shops dispersed globally and will require unique equipment for their safe handling, transportation and subsequent erection. The challenge is to design the lifting attachments in such a manner that the attachments provide a safe, cost effective and effective solution based upon the limitations of the job site lift equipment available for erection. Such equipment for the transportation and subsequent lifting of large diameter and heavy wall pressure equipment is usually scarce and quite expensive. Planning ahead, well in advance of the lift date is almost a mandatory requirement. Usually, the specific parameters of the vessel to be lifted and the lifting equipment available at the site will dictate the type of lifting attachments to be designed for the vessel. Once the type of vessel attachment has been chosen, careful consideration must be given to the design of attachments to the pressure vessel in consideration to ensure that the vessel and lifting components are not overstressed during the lifting process. The paper also discusses different types of lifting attachments that may be attached to each end of the vessel either by bolting or welding and discusses the pros and cons of each. The paper also provides an example of a finite element analysis (FEA) of a top nozzle, a FEA of a pair of lifting trunnions and a FEA of welded on lifting lugs for buried pipe. The purpose of the paper is to outline the

  6. SWEPT-SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY REVEALS INTERNAL LIMITING MEMBRANE PEELING ALTERS DEEP RETINAL VASCULATURE.

    Science.gov (United States)

    Michalewska, Zofia; Nawrocki, Jerzy

    2018-04-30

    To describe morphology of retinal and choroidal vessels in swept-source optical coherence tomography angiography before and after vitrectomy with the temporal inverted internal limiting membrane (ILM) flap technique for full-thickness macular holes. Prospective, observational study of 36 eyes of 33 patients with full-thickness macular holes swept-source optical coherence tomography angiography was performed in patients before and 1 month after vitrectomy. Vitrectomy with the temporal inverted ILM flap technique was performed. In this method, ILM is peeled only at one side of the fovea. An ILM flap is created to cover the macular hole. Comparison of retina vasculature in the areas of ILM peeling vs. no ILM peeling at 1 and 3 months after successful vitrectomy was performed. The study demonstrated lower density of vessels in the deep retinal plexus in the area where ILM was peeled as compared to the rest of the fovea. Visual acuity and central retinal thickness 1 month after surgery correlates with fovea avascular zone diameter in deep retinal layers at the same time point (P = 0.001). This study confirmed that ILM peeling might alter blood flow in deep retinal vessels below the peeling area in the early postoperative period. The area of the fovea avascular zone corresponds to functional results at the same time point.

  7. Pulmonary artery pulsatility and effect on vessel diameter assessment in magnetic resonance imaging

    International Nuclear Information System (INIS)

    Shariat, Masoud; Schantz, Daryl; Yoo, Shi-Joon; Wintersperger, Bernd J.; Seed, Mike; Alnafisi, Bahiyah; Chu, Leysia; MacGowan, Christopher K.; Amerom, Joshua van; Grosse-Wortmann, Lars

    2014-01-01

    Background: Information about thoracic vascular sizes can crucially affect clinical decision-making in cardiovascular disease. A variety of imaging techniques such as catheter angiography, contrast enhanced computed tomography (CT) and cardiac magnetic resonance imaging (CMR) are routinely used to measure vascular diameters. Traditionally, CMR black blood sequences were the main anatomical tool for visualization of vascular anatomy and still are in many centers. More recently, the vessel diameters are measured on multiplanar reconstructions derived from static magnetic resonance angiography (MRA). This study was performed to investigate the variation of vessel diameter measurements on different CMR techniques with respect to their data acquisition scheme. Methods: We recruited two groups of patients for this prospective study. One group included patients with repaired tetralogy of Fallot (TOF), with at least moderate pulmonary insufficiency and another group of patients who underwent CMR as part of a diagnostic work-up for arrhythmogenic right ventricular cardiomyopathy (ARVC). Additional images of the right pulmonary artery (RPA) were acquired in the double inversion recovery (DIR) black blood, cine steady state free precession (SSFP) and MRA. All images were reviewed by two CMR trained readers using the electronic caliper provided within the picture archiving and communication system package. The maximum diameter of each artery was recorded in millimeters with up to one decimal point. Paired t-tests and Bland–Altman plots were used for comparison of measurements between different sequences. Results: A total of 52 patients were recruited for this study, 26 patients in the TOF group (15 males, age 12.55 ± 2.9) and 26 patients in the ARVC group (15 males, age 15.6 ± 2.3). In both groups, the RPA sizes were not significantly different between the DIR images and diastolic cine SSFP (p > 0.05). Measurements on DIR were significantly smaller than those made on

  8. Pulmonary artery pulsatility and effect on vessel diameter assessment in magnetic resonance imaging

    Energy Technology Data Exchange (ETDEWEB)

    Shariat, Masoud, E-mail: masoudshariat@gmail.com [Department of Medical Imaging, University Health Network, University of Toronto, Toronto, Ontario (Canada); Department of Diagnostic Imaging, Hospital for Sick Children, Toronto, Ontario (Canada); Schantz, Daryl, E-mail: daryl.schantz@gmail.com [Department of Diagnostic Imaging, Hospital for Sick Children, Toronto, Ontario (Canada); Yoo, Shi-Joon, E-mail: shi-joon.yoo@sickkids.ca [Department of Diagnostic Imaging, Hospital for Sick Children, Toronto, Ontario (Canada); Wintersperger, Bernd J., E-mail: bernd.wintersperger@uhn.ca [Department of Medical Imaging, University Health Network, University of Toronto, Toronto, Ontario (Canada); Seed, Mike, E-mail: mike.seed@sickkids.ca [Department of Diagnostic Imaging, Hospital for Sick Children, Toronto, Ontario (Canada); Department of Cardiology, Hospital for Sick Children, Toronto, Ontario (Canada); Alnafisi, Bahiyah, E-mail: bahiyah.alnafisi@uhn.ca [Department of Medical Imaging, University Health Network, University of Toronto, Toronto, Ontario (Canada); Chu, Leysia, E-mail: leysia_99@yahoo.com [Department of Diagnostic Imaging, Hospital for Sick Children, Toronto, Ontario (Canada); MacGowan, Christopher K., E-mail: christopher.macgowan@sickkids.ca [Department of Physiology and Experimental Medicine, Hospital for Sick Children, Toronto, Ontario (Canada); Amerom, Joshua van, E-mail: Joshu.vanamerom@sickkids.ca [Department of Physiology and Experimental Medicine, Hospital for Sick Children, Toronto, Ontario (Canada); Grosse-Wortmann, Lars, E-mail: lars.grosse-wortmann@sickkids.ca [Department of Diagnostic Imaging, Hospital for Sick Children, Toronto, Ontario (Canada); Department of Cardiology, Hospital for Sick Children, Toronto, Ontario (Canada)

    2014-02-15

    Background: Information about thoracic vascular sizes can crucially affect clinical decision-making in cardiovascular disease. A variety of imaging techniques such as catheter angiography, contrast enhanced computed tomography (CT) and cardiac magnetic resonance imaging (CMR) are routinely used to measure vascular diameters. Traditionally, CMR black blood sequences were the main anatomical tool for visualization of vascular anatomy and still are in many centers. More recently, the vessel diameters are measured on multiplanar reconstructions derived from static magnetic resonance angiography (MRA). This study was performed to investigate the variation of vessel diameter measurements on different CMR techniques with respect to their data acquisition scheme. Methods: We recruited two groups of patients for this prospective study. One group included patients with repaired tetralogy of Fallot (TOF), with at least moderate pulmonary insufficiency and another group of patients who underwent CMR as part of a diagnostic work-up for arrhythmogenic right ventricular cardiomyopathy (ARVC). Additional images of the right pulmonary artery (RPA) were acquired in the double inversion recovery (DIR) black blood, cine steady state free precession (SSFP) and MRA. All images were reviewed by two CMR trained readers using the electronic caliper provided within the picture archiving and communication system package. The maximum diameter of each artery was recorded in millimeters with up to one decimal point. Paired t-tests and Bland–Altman plots were used for comparison of measurements between different sequences. Results: A total of 52 patients were recruited for this study, 26 patients in the TOF group (15 males, age 12.55 ± 2.9) and 26 patients in the ARVC group (15 males, age 15.6 ± 2.3). In both groups, the RPA sizes were not significantly different between the DIR images and diastolic cine SSFP (p > 0.05). Measurements on DIR were significantly smaller than those made on

  9. A clinical approach to the diagnosis of retinal vasculitis.

    Science.gov (United States)

    El-Asrar, Ahmed M Abu; Herbort, Carl P; Tabbara, Khalid F

    2010-04-01

    Retinal vasculitis is a sight-threatening inflammatory eye condition that involves the retinal vessels. Detection of retinal vasculitis is made clinically, and is confirmed with the help of fundus fluorescein angiography. Active vascular disease is characterized by exudates around retinal vessels resulting in white sheathing or cuffing of the affected vessels. In this review, a practical approach to the diagnosis of retinal vasculitis is discussed based on ophthalmoscopic and fundus fluorescein angiographic findings.

  10. Scleral electrocautery and its effects on choroid vessels: implications for subretinal fluid drainage during scleral buckling surgery.

    Science.gov (United States)

    Roybal, C Nathaniel; Tsui, Irena; Sanfilippo, Christian; Hubschman, Jean-Pierre

    2013-01-01

    External drainage of subretinal fluid as part of a scleral buckling procedure rapidly restores the retinal pigment epithelium-neural retina interface in rhegmatogenous retinal detachments but carries the inherent risk of subretinal hemorrhage and retinal incarceration. The authors investigated variations to the technique to reduce the chance of subretinal hemorrhage originating from the choroid. A novel method for needle drainage using electrocautery of the sclerochoroidal layers before puncture was employed. The effect of 0% to 50% scleral electrocautery in a porcine model was investigated. A significant decrease in choroidal vessel diameter and choroidal vessel density at 40% electrocautery was demonstrated. Electrocautery without scleral cut-down before external drainage of subretinal fluid likely decreases the chance of subretinal hemorrhage by decreasing choroidal vascularity. Copyright 2013, SLACK Incorporated.

  11. Movement of retinal vessels toward the optic nerve head after increasing intraocular pressure in monkey eyes with experimental glaucoma.

    Science.gov (United States)

    Kuroda, Atsumi; Enomoto, Nobuko; Ishida, Kyoko; Shimazawa, Masamitsu; Noguchi, Tetsuro; Horai, Naoto; Onoe, Hirotaka; Hara, Hideaki; Tomita, Goji

    2017-09-01

    A shift or displacement of the retinal blood vessels (RBVs) with neuroretinal rim thinning indicates the progression of glaucomatous optic neuropathy. In chronic open angle glaucoma, individuals with RBV positional shifts exhibit more rapid visual field loss than those without RBV shifts. The retinal vessels reportedly move onto the optic nerve head (ONH) in response to glaucoma damage, suggesting that RBVs are pulled toward the ONH in response to increased cupping. Whether this phenomenon only applies to RVBs located in the vicinity or inside the ONH or, more generally, to RBVs also located far from the ONH, however, is unclear. The aim of this study was to evaluate the movement of RBVs located relatively far from the ONH edge after increasing intraocular pressure (IOP) in an experimental monkey model of glaucoma. Fundus photographs were obtained in 17 monkeys. High IOP was induced in the monkeys by laser photocoagulation burns applied uniformly with 360° irradiation around the trabecular meshwork of the left eye. The right eye was left intact and used as a non-treated control. Considering the circadian rhythm of IOP, it was measured in both eyes of each animal at around the same time-points. Then, fundus photographs were obtained. Using Image J image analysis software, an examiner (N.E.) measured the fundus photographs at two time-points, i.e. before laser treatment (time 1) and the last fundus photography after IOP elevation (time 2). The following parameters were measured (in pixels): 1) vertical diameter of the ONH (DD), 2) distance from the ONH edge to the first bifurcation point of the superior branch of the central retinal vein (UV), 3) distance from the ONH edge to the first bifurcation point of the inferior branch of the central retinal vein (LV), 4) ONH area, and 5) surface area of the cup of the ONH. We calculated the ratios of UV to DD (UV/DD), LV to DD (LV/DD), and the cup area to disc area ratio (C/D). The mean UV/DD at time 1 (0.656 ± 0.233) was

  12. Accelerated and Improved Differentiation of Retinal Organoids from Pluripotent Stem Cells in Rotating-Wall Vessel Bioreactors

    Directory of Open Access Journals (Sweden)

    Tyler DiStefano

    2018-01-01

    Full Text Available Pluripotent stem cells can be differentiated into 3D retinal organoids, with major cell types self-patterning into a polarized, laminated architecture. In static cultures, organoid development may be hindered by limitations in diffusion of oxygen and nutrients. Herein, we report a bioprocess using rotating-wall vessel (RWV bioreactors to culture retinal organoids derived from mouse pluripotent stem cells. Organoids in RWV demonstrate enhanced proliferation, with well-defined morphology and improved differentiation of neurons including ganglion cells and S-cone photoreceptors. Furthermore, RWV organoids at day 25 (D25 reveal similar maturation and transcriptome profile as those at D32 in static culture, closely recapitulating spatiotemporal development of postnatal day 6 mouse retina in vivo. Interestingly, however, retinal organoids do not differentiate further under any in vitro condition tested here, suggesting additional requirements for functional maturation. Our studies demonstrate that bioreactors can accelerate and improve organoid growth and differentiation for modeling retinal disease and evaluation of therapies.

  13. Estimation of vessel diameter and blood flow dynamics from laser speckle images

    DEFF Research Database (Denmark)

    Postnov, Dmitry D.; Tuchin, Valery V.; Sosnovtseva, Olga

    2016-01-01

    Laser speckle imaging is a rapidly developing method to study changes of blood velocity in the vascular networks. However, to assess blood flow and vascular responses it is crucial to measure vessel diameter in addition to blood velocity dynamics. We suggest an algorithm that allows for dynamical...

  14. Genetic determinants of hyaloid and retinal vasculature in zebrafish

    Directory of Open Access Journals (Sweden)

    Hyde David R

    2007-10-01

    Full Text Available Abstract Background The retinal vasculature is a capillary network of blood vessels that nourishes the inner retina of most mammals. Developmental abnormalities or microvascular complications in the retinal vasculature result in severe human eye diseases that lead to blindness. To exploit the advantages of zebrafish for genetic, developmental and pharmacological studies of retinal vasculature, we characterised the intraocular vasculature in zebrafish. Results We show a detailed morphological and developmental analysis of the retinal blood supply in zebrafish. Similar to the transient hyaloid vasculature in mammalian embryos, vessels are first found attached to the zebrafish lens at 2.5 days post fertilisation. These vessels progressively lose contact with the lens and by 30 days post fertilisation adhere to the inner limiting membrane of the juvenile retina. Ultrastructure analysis shows these vessels to exhibit distinctive hallmarks of mammalian retinal vasculature. For example, smooth muscle actin-expressing pericytes are ensheathed by the basal lamina of the blood vessel, and vesicle vacuolar organelles (VVO, subcellular mediators of vessel-retinal nourishment, are present. Finally, we identify 9 genes with cell membrane, extracellular matrix and unknown identity that are necessary for zebrafish hyaloid and retinal vasculature development. Conclusion Zebrafish have a retinal blood supply with a characteristic developmental and adult morphology. Abnormalities of these intraocular vessels are easily observed, enabling application of genetic and chemical approaches in zebrafish to identify molecular regulators of hyaloid and retinal vasculature in development and disease.

  15. Retinal characteristics during 1 year of insulin pump therapy in type 1 diabetes

    DEFF Research Database (Denmark)

    Klefter, Oliver Niels; Hommel, Eva; Munch, Inger Christine

    2016-01-01

    of CSII led to an HbA1c reduction relative to continued MDI and a small increase in retinal thickness but not to early retinopathy worsening or to changes in retinal vascular, structural or functional characteristics. Longer duration of type 1 diabetes appears to be associated with lower macular venous......PURPOSE: To investigate changes in retinal metabolism, function, structure and morphology in relation to initiation of insulin pump therapy (continuous subcutaneous insulin infusion, CSII). METHODS: Visual acuity, retinopathy level, dark adaptation kinetics, retinal and subfoveal choroidal...... thickness, macular perfusion velocities, retinal vessel diameters and blood oxygen saturations were measured at baseline and after 1, 4, 16, 32 and 52 weeks in 31 patients with type 1 diabetes who started CSII and 20 patients who continued multiple daily insulin injections (MDI). RESULTS: One year of CSII...

  16. Retinal biometrics based on Iterative Closest Point algorithm.

    Science.gov (United States)

    Hatanaka, Yuji; Tajima, Mikiya; Kawasaki, Ryo; Saito, Koko; Ogohara, Kazunori; Muramatsu, Chisako; Sunayama, Wataru; Fujita, Hiroshi

    2017-07-01

    The pattern of blood vessels in the eye is unique to each person because it rarely changes over time. Therefore, it is well known that retinal blood vessels are useful for biometrics. This paper describes a biometrics method using the Jaccard similarity coefficient (JSC) based on blood vessel regions in retinal image pairs. The retinal image pairs were rough matched by the center of their optic discs. Moreover, the image pairs were aligned using the Iterative Closest Point algorithm based on detailed blood vessel skeletons. For registration, perspective transform was applied to the retinal images. Finally, the pairs were classified as either correct or incorrect using the JSC of the blood vessel region in the image pairs. The proposed method was applied to temporal retinal images, which were obtained in 2009 (695 images) and 2013 (87 images). The 87 images acquired in 2013 were all from persons already examined in 2009. The accuracy of the proposed method reached 100%.

  17. An Automatic Cognitive Graph-Based Segmentation for Detection of Blood Vessels in Retinal Images

    Directory of Open Access Journals (Sweden)

    Rasha Al Shehhi

    2016-01-01

    Full Text Available This paper presents a hierarchical graph-based segmentation for blood vessel detection in digital retinal images. This segmentation employs some of perceptual Gestalt principles: similarity, closure, continuity, and proximity to merge segments into coherent connected vessel-like patterns. The integration of Gestalt principles is based on object-based features (e.g., color and black top-hat (BTH morphology and context and graph-analysis algorithms (e.g., Dijkstra path. The segmentation framework consists of two main steps: preprocessing and multiscale graph-based segmentation. Preprocessing is to enhance lighting condition, due to low illumination contrast, and to construct necessary features to enhance vessel structure due to sensitivity of vessel patterns to multiscale/multiorientation structure. Graph-based segmentation is to decrease computational processing required for region of interest into most semantic objects. The segmentation was evaluated on three publicly available datasets. Experimental results show that preprocessing stage achieves better results compared to state-of-the-art enhancement methods. The performance of the proposed graph-based segmentation is found to be consistent and comparable to other existing methods, with improved capability of detecting small/thin vessels.

  18. Effects of hyperbaric, normobaric and hypobaric oxygen supplementation on retinal vessels in newborn rats: a preliminary study.

    Science.gov (United States)

    Ricci, B

    1987-03-01

    An experimental study was conducted on eight litters of newborn rats to evaluate the effects of supplemental oxygen administration on the retinal vasculature. The animals and their mothers were kept inside a pressure chamber and treated for the first 5 days of life. On the sixth day, they were removed and kept for five more days under room air and normobaric conditions. Three litters received continuous flow oxygen at 80% at a compression pressure of +81 kPa, one litter oxygen at 80% at a pressure of -39.5 kPa atms and three other litters received oxygen at 80% under normobaric conditions. The eighth litter was treated with room air oxygen at a compression pressure of +81 kPa. A severe retinopathy with marked retinal neovascularization was seen only in the newborn animals of the litters that received oxygen supplementation under normobaric or hypobaric conditions. Retinal vessels showed no pathological changes in the litters treated with hyperbaric normoxia or hyperoxia. It is possible to hypothesize that the prolonged period of oxygen supplementation failed to produce harmful effects on the retinal vasculature because the moderate hyperbarism caused mild retinal and choroidal vasoconstriction thus preventing excessive oxygen transport to the inner retina from the choroid during hyperoxia without inducing structural damage to the retinal tissue.

  19. Inter-arm Blood Pressure Difference and its Relationship with Retinal Microvascular Calibres in Young Individuals: The African-PREDICT Study.

    Science.gov (United States)

    Strauss, Michél; Smith, Wayne; Schutte, Aletta E

    2016-08-01

    Bilateral systolic blood pressure (SBP) differences > 10mmHg is a common finding in clinical practice. Such BP differences in older individuals are associated with peripheral vascular disease, linked to microvascular dysfunction. Investigating retinal vessel calibres could provide insight into systemic microvascular function and may predict cardiovascular outcomes. Therefore we investigated the link between inter-arm systolic blood pressure differences (IASBPD) and the retinal microvasculature to determine the usefulness of IASBPD as an early marker of microvascular changes. In this cross-sectional study, we used data from 403 apparently healthy participants (20-30 years) (42% men; 49% black) taking part in the African-PREDICT study. Participants underwent retinal vessel imaging, anthropometric measurements and blood sampling. Brachial BP was measured sequentially in both arms to determine the mean IASBPD. Participants were stratified into two groups with an IASBPD difference in characteristics being a higher right arm SBP in the latter group (p=0.005). We found no association between IASBPD and retinal vessel calibres in any group. Less than 2% of the variance in IASBPD was explained by potential risk factors, with only SBP associating independently with IASBPD (β=115; p=0.039). In a young population an increased IASBPD is not related to retinal vessel diameters suggesting that it does not reflect early microvascular alterations. Copyright © 2016 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

  20. Classic beta-amyloid deposits cluster around large diameter blood vessels rather than capillaries in sporadic Alzheimer's disease.

    Science.gov (United States)

    Armstrong, Richard A

    2006-11-01

    Various hypotheses could explain the relationship between beta-amyloid (Abeta) deposition and the vasculature in Alzheimer's disease (AD). Amyloid deposition may reduce capillary density, affect endothelial cells of blood vessels, result in diffusion from blood vessels, or interfere with the perivascular clearance mechanism. Hence, the spatial pattern of the classic ('cored') type of Abeta deposit was studied in the upper laminae (I,II/III) of the superior frontal gyrus in nine cases of sporadic AD (SAD). Sections were immunostained with antibodies against Abeta and with collagen IV to study the relationships between the spatial distribution of the classic deposits and the blood vessel profiles. Both the classic deposits and blood vessel profiles were distributed in clusters. In all cases, there was a positive spatial correlation between the clusters of the classic deposits and the larger diameter (>10 microm) blood vessel profiles and especially the vertically penetrating arterioles. In only 1 case, was there a significant spatial correlation between the clusters of the classic deposits and the smaller diameter (upper laminae of the frontal cortex. This aggregation could result from diffusion of proteins from blood vessels or from overloading the system of perivascular clearance from the brain.

  1. Retinal vascular speed prematurity requiring treatment.

    Science.gov (United States)

    Solans Pérez de Larraya, Ana M; Ortega Molina, José M; Fernández, José Uberos; Escudero Gómez, Júlia; Salgado Miranda, Andrés D; Chaves Samaniego, Maria J; García Serrano, José L

    2018-03-01

    To analyse the speed of temporal retinal vascularisation in preterm infants included in the screening programme for retinopathy of prematurity. A total of 185 premature infants were studied retrospectively between 2000 and 2017 in San Cecilio University Hospital of Granada, Spain. The method of binocular indirect ophthalmoscopy with indentation was used for the examination. The horizontal disc diameter was used as a unit of length. Speed of temporal retinal vascularisation (disc diameter/week) was calculated as the ratio between the extent of temporal retinal vascularisation (disc diameter) and the time in weeks. The weekly temporal retinal vascularisation (0-1.25 disc diameter/week, confidence interval) was significantly higher in no retinopathy of prematurity (0.73 ± 0.22 disc diameter/week) than in stage 1 retinopathy of prematurity (0.58 ± 0.22 disc diameter/week). It was also higher in stage 1 than in stages 2 (0.46 ± 0.14 disc diameter/week) and 3 of retinopathy of prematurity (0.36 ± 0.18 disc diameter/week). The rate of temporal retinal vascularisation (disc diameter/week) decreases when retinopathy of prematurity stage increases. The area under the receiver operating characteristic curve was 0.85 (95% confidence interval: 0.79-0.91) for retinopathy of prematurity requiring treatment versus not requiring treatment. The best discriminative cut-off point was a speed of retinal vascularisation prematurity may be required. However, before becoming a new standard of care for treatment, it requires careful documentation, with agreement between several ophthalmologists.

  2. Rat retinal vasomotion assessed by laser speckle imaging

    DEFF Research Database (Denmark)

    Neganova, Anastasiia Y; Postnov, Dmitry D; Sosnovtseva, Olga

    2017-01-01

    Vasomotion is spontaneous or induced rhythmic changes in vascular tone or vessel diameter that lead to rhythmic changes in flow. While the vascular research community debates the physiological and pathophysiological consequence of vasomotion, there is a great need for experimental techniques...... that can address the role and dynamical properties of vasomotion in vivo. We apply laser speckle imaging to study spontaneous and drug induced vasomotion in retinal network of anesthetized rats. The results reveal a wide variety of dynamical patterns. Wavelet-based analysis shows that (i) spontaneous...

  3. Retinal blood vessel segmentation in high resolution fundus photographs using automated feature parameter estimation

    Science.gov (United States)

    Orlando, José Ignacio; Fracchia, Marcos; del Río, Valeria; del Fresno, Mariana

    2017-11-01

    Several ophthalmological and systemic diseases are manifested through pathological changes in the properties and the distribution of the retinal blood vessels. The characterization of such alterations requires the segmentation of the vasculature, which is a tedious and time-consuming task that is infeasible to be performed manually. Numerous attempts have been made to propose automated methods for segmenting the retinal vasculature from fundus photographs, although their application in real clinical scenarios is usually limited by their ability to deal with images taken at different resolutions. This is likely due to the large number of parameters that have to be properly calibrated according to each image scale. In this paper we propose to apply a novel strategy for automated feature parameter estimation, combined with a vessel segmentation method based on fully connected conditional random fields. The estimation model is learned by linear regression from structural properties of the images and known optimal configurations, that were previously obtained for low resolution data sets. Our experiments in high resolution images show that this approach is able to estimate appropriate configurations that are suitable for performing the segmentation task without requiring to re-engineer parameters. Furthermore, our combined approach reported state of the art performance on the benchmark data set HRF, as measured in terms of the F1-score and the Matthews correlation coefficient.

  4. Retinal vasculitis.

    Science.gov (United States)

    Abu El-Asrar, Ahmed M; Herbort, Carl P; Tabbara, Khalid F

    2005-12-01

    Retinal vasculitis is a sight-threatening intraocular inflammation affecting the retinal vessels. It may occur as an isolated ocular condition, as a manifestation of infectious or neoplastic disorders, or in association with a systemic inflammatory disease. The search for an underlying etiology should be approached in a multidisciplinary fashion based on a thorough history, review of systems, physical examination, and laboratory evaluation. Discrimination between infectious and noninfectious etiologies of retinal vasculitis is important because their treatment is different. This review is based on recently published articles on retinal vasculitis and deals with its clinical diagnosis, its link with systemic diseases, and its laboratory investigation.

  5. Quantification of retinal tangential movement in epiretinal membranes

    DEFF Research Database (Denmark)

    Kofod, Mads; la Cour, Morten

    2012-01-01

    To describe a technique of quantifying retinal vessel movement in eyes with epiretinal membrane (ERM) and correlate the retinal vessel movement with changes in best-corrected visual acuity (BCVA), central macular thickness (CMT), and patients' subjective reports about experienced symptoms (sympto...

  6. The dimensional changes of a 24 inch diameter vessel during a campaign of successive glass making runs

    International Nuclear Information System (INIS)

    Chidley, B.E.

    1983-01-01

    Throughout the life of a 24 inch diameter Glass Making Vessel used on the inactive Harvest Vitrification Plant dimensional measurements have been recorded. When glass is present the diameter increases due to thermal stresses. Some permanent longitudinal extension (about 1%) occurred over the 20 runs comprising the glass-making campaign. (author)

  7. Association of Retinopathy and Retinal Microvascular Abnormalities With Stroke and Cerebrovascular Disease.

    Science.gov (United States)

    Hughes, Alun D; Falaschetti, Emanuela; Witt, Nicholas; Wijetunge, Sumangali; Thom, Simon A McG; Tillin, Therese; Aldington, Steve J; Chaturvedi, Nish

    2016-11-01

    Abnormalities of the retinal circulation may be associated with cerebrovascular disease. We investigated associations between retinal microvascular abnormalities and (1) strokes and subclinical cerebral infarcts and (2) cerebral white matter lesions in a UK-based triethnic population-based cohort. A total of 1185 participants (age, 68.8±6.1 years; 77% men) underwent retinal imaging and cerebral magnetic resonance imaging. Cerebral infarcts and white matter hyperintensities were identified on magnetic resonance imaging, retinopathy was graded, and retinal vessels were measured. Higher retinopathy grade (odds ratio [OR], 1.40 [95% confidence interval (95% CI), 1.16-1.70]), narrower arteriolar diameter (OR, 0.98 [95% CI, 0.97-0.99]), fewer symmetrical arteriolar bifurcations (OR, 0.84 [95% CI, 0.75-0.95]), higher arteriolar optimality deviation (OR, 1.16 [95% CI, 1.00-1.34]), and more tortuous venules (OR, 1.20 [95% CI, 1.09-1.32]) were associated with strokes/infarcts and white matter hyperintensities. Associations with quantitative retinal microvascular measures were independent of retinopathy. Abnormalities of the retinal microvasculature are independently associated with stroke, cerebral infarcts, and white matter lesions. © 2016 American Heart Association, Inc.

  8. Protein kinase C in porcine retinal arteries and neuroretina following retinal ischemia-reperfusion

    DEFF Research Database (Denmark)

    Gesslein, Bodil; Gustafsson, Lotta; Wackenfors, Angelica

    2009-01-01

    Identification of the intracellular signal-transduction pathways activated in retinal ischemia may be important in revealing novel pharmacological targets. To date, most studies have focused on identifying neuroprotective agents. The retinal blood vessels are key organs in circulatory failure, an...

  9. Automated detection and measurement of isolated retinal arterioles by a combination of edge enhancement and cost analysis.

    Directory of Open Access Journals (Sweden)

    José A Fernández

    Full Text Available Pressure myography studies have played a crucial role in our understanding of vascular physiology and pathophysiology. Such studies depend upon the reliable measurement of changes in the diameter of isolated vessel segments over time. Although several software packages are available to carry out such measurements on small arteries and veins, no such software exists to study smaller vessels (<50 µm in diameter. We provide here a new, freely available open-source algorithm, MyoTracker, to measure and track changes in the diameter of small isolated retinal arterioles. The program has been developed as an ImageJ plug-in and uses a combination of cost analysis and edge enhancement to detect the vessel walls. In tests performed on a dataset of 102 images, automatic measurements were found to be comparable to those of manual ones. The program was also able to track both fast and slow constrictions and dilations during intraluminal pressure changes and following application of several drugs. Variability in automated measurements during analysis of videos and processing times were also investigated and are reported. MyoTracker is a new software to assist during pressure myography experiments on small isolated retinal arterioles. It provides fast and accurate measurements with low levels of noise and works with both individual images and videos. Although the program was developed to work with small arterioles, it is also capable of tracking the walls of other types of microvessels, including venules and capillaries. It also works well with larger arteries, and therefore may provide an alternative to other packages developed for larger vessels when its features are considered advantageous.

  10. [Hemodynamic phenomena in retrobulhar and eyeball vessels].

    Science.gov (United States)

    Modrzejewska, Monika

    2011-01-01

    The purpose of this review was to evaluate factors connected with blood flow and indices regulating vascular diameter and some parameters influencing retrobulbar circulation such as type of vascular resistance, anatomical structure of vascular wall and vessel lumen. Neurogenic and angiogenic factors, rheological blood composition, presence of anatomical and pathological obstructions on blood flow pathway as well as degree of development of collateral circulation pathways--have influence on the volume and blood flow velocity in eyeball. There were discussed bulbar circulation hemodynamics, emphasizing the importance of perfusion pressure. The role of risk factors was underlined for pathological lesions in vessels supplying blood to eyeball and in ophthalmic artery (OA) and its collaterals, in central retinal artery (CRA) as well as posterior ciliary arteries (PCAs), and in venous system carrying away blood from eye. IN CONCLUSION--the results of many studies of retrobulbar blood flow in different types of ophthalmic diseases of the vascular etiopathogenesis indicate that registry of the mean values of blood flow parameters and vascular resistance indices parallel to measurement of blood flow spectrum in OA, CRA, PCAs arteries, might contribute much information to explain or to evaluate nature of pathological changes in retinal and choroidal circulation.

  11. Turbulent flow in a vessel agitated by side entering inclined blade turbine with different diameter using CFD simulation

    Science.gov (United States)

    Fathonah, N. N.; Nurtono, T.; Kusdianto; Winardi, S.

    2018-03-01

    Single phase turbulent flow in a vessel agitated by side entering inclined blade turbine has simulated using CFD. The aim of this work is to identify the hydrodynamic characteristics of a model vessel, which geometrical configuration is adopted at industrial scale. The laboratory scale model vessel is a flat bottomed cylindrical tank agitated by side entering 4-blade inclined blade turbine with impeller rotational speed N=100-400 rpm. The effect of the impeller diameter on fluid flow pattern has been investigated. The fluid flow patterns in a vessel is essentially characterized by the phenomena of macro-instabilities, i.e. the flow patterns change with large scale in space and low frequency. The intensity of fluid flow in the tank increase with the increase of impeller rotational speed from 100, 200, 300, and 400 rpm. It was accompanied by shifting the position of the core of circulation flow away from impeller discharge stream and approached the front of the tank wall. The intensity of fluid flow in the vessel increase with the increase of the impeller diameter from d=3 cm to d=4 cm.

  12. Feature-Based Retinal Image Registration Using D-Saddle Feature

    Directory of Open Access Journals (Sweden)

    Roziana Ramli

    2017-01-01

    Full Text Available Retinal image registration is important to assist diagnosis and monitor retinal diseases, such as diabetic retinopathy and glaucoma. However, registering retinal images for various registration applications requires the detection and distribution of feature points on the low-quality region that consists of vessels of varying contrast and sizes. A recent feature detector known as Saddle detects feature points on vessels that are poorly distributed and densely positioned on strong contrast vessels. Therefore, we propose a multiresolution difference of Gaussian pyramid with Saddle detector (D-Saddle to detect feature points on the low-quality region that consists of vessels with varying contrast and sizes. D-Saddle is tested on Fundus Image Registration (FIRE Dataset that consists of 134 retinal image pairs. Experimental results show that D-Saddle successfully registered 43% of retinal image pairs with average registration accuracy of 2.329 pixels while a lower success rate is observed in other four state-of-the-art retinal image registration methods GDB-ICP (28%, Harris-PIIFD (4%, H-M (16%, and Saddle (16%. Furthermore, the registration accuracy of D-Saddle has the weakest correlation (Spearman with the intensity uniformity metric among all methods. Finally, the paired t-test shows that D-Saddle significantly improved the overall registration accuracy of the original Saddle.

  13. Personal identification based on blood vessels of retinal fundus images

    Science.gov (United States)

    Fukuta, Keisuke; Nakagawa, Toshiaki; Hayashi, Yoshinori; Hatanaka, Yuji; Hara, Takeshi; Fujita, Hiroshi

    2008-03-01

    Biometric technique has been implemented instead of conventional identification methods such as password in computer, automatic teller machine (ATM), and entrance and exit management system. We propose a personal identification (PI) system using color retinal fundus images which are unique to each individual. The proposed procedure for identification is based on comparison of an input fundus image with reference fundus images in the database. In the first step, registration between the input image and the reference image is performed. The step includes translational and rotational movement. The PI is based on the measure of similarity between blood vessel images generated from the input and reference images. The similarity measure is defined as the cross-correlation coefficient calculated from the pixel values. When the similarity is greater than a predetermined threshold, the input image is identified. This means both the input and the reference images are associated to the same person. Four hundred sixty-two fundus images including forty-one same-person's image pairs were used for the estimation of the proposed technique. The false rejection rate and the false acceptance rate were 9.9×10 -5% and 4.3×10 -5%, respectively. The results indicate that the proposed method has a higher performance than other biometrics except for DNA. To be used for practical application in the public, the device which can take retinal fundus images easily is needed. The proposed method is applied to not only the PI but also the system which warns about misfiling of fundus images in medical facilities.

  14. Blood vessel classification into arteries and veins in retinal images

    Science.gov (United States)

    Kondermann, Claudia; Kondermann, Daniel; Yan, Michelle

    2007-03-01

    The prevalence of diabetes is expected to increase dramatically in coming years; already today it accounts for a major proportion of the health care budget in many countries. Diabetic Retinopathy (DR), a micro vascular complication very often seen in diabetes patients, is the most common cause of visual loss in working age population of developed countries today. Since the possibility of slowing or even stopping the progress of this disease depends on the early detection of DR, an automatic analysis of fundus images would be of great help to the ophthalmologist due to the small size of the symptoms and the large number of patients. An important symptom for DR are abnormally wide veins leading to an unusually low ratio of the average diameter of arteries to veins (AVR). There are also other diseases like high blood pressure or diseases of the pancreas with one symptom being an abnormal AVR value. To determine it, a classification of vessels as arteries or veins is indispensable. As to our knowledge despite the importance there have only been two approaches to vessel classification yet. Therefore we propose an improved method. We compare two feature extraction methods and two classification methods based on support vector machines and neural networks. Given a hand-segmentation of vessels our approach achieves 95.32% correctly classified vessel pixels. This value decreases by 10% on average, if the result of a segmentation algorithm is used as basis for the classification.

  15. EFFECTUAL HUMAN AUTHENTICATION FOR CRITICAL SECURITY APPLICATIONS USING RETINAL IMAGES

    Directory of Open Access Journals (Sweden)

    L. Latha

    2010-11-01

    Full Text Available A robust method of human authentication based on the retinal blood vessel pattern is presented in this paper. This method entails a segmentation process to identify retinal blood vessel pattern, template generation consisting of the bifurcation points in the retina and matching of the intersection points in the template patterns. The number of matched blood vessel intersection points between the two patterns compared is used as a measure of similarity. As Liveness detection is a highly desirable anti-spoofing measure in biometric authentication, it is ensured while acquiring retinal images in realtime. The validity of our approach is verified with experimental results obtained from 603 comparisons made using 303 retinal images from three different publicly available databases, namely DRIVE, VARIA and STARE. We found that the proposed retinal recognition method gives 100%, 96.3% and 91.1% recognition rates respectively for the above databases. To the best of our knowledge, this is the first work that uses a large number of retinal images from different retinal databases for the authentication purpose.

  16. End-to-End Adversarial Retinal Image Synthesis.

    Science.gov (United States)

    Costa, Pedro; Galdran, Adrian; Meyer, Maria Ines; Niemeijer, Meindert; Abramoff, Michael; Mendonca, Ana Maria; Campilho, Aurelio

    2018-03-01

    In medical image analysis applications, the availability of the large amounts of annotated data is becoming increasingly critical. However, annotated medical data is often scarce and costly to obtain. In this paper, we address the problem of synthesizing retinal color images by applying recent techniques based on adversarial learning. In this setting, a generative model is trained to maximize a loss function provided by a second model attempting to classify its output into real or synthetic. In particular, we propose to implement an adversarial autoencoder for the task of retinal vessel network synthesis. We use the generated vessel trees as an intermediate stage for the generation of color retinal images, which is accomplished with a generative adversarial network. Both models require the optimization of almost everywhere differentiable loss functions, which allows us to train them jointly. The resulting model offers an end-to-end retinal image synthesis system capable of generating as many retinal images as the user requires, with their corresponding vessel networks, by sampling from a simple probability distribution that we impose to the associated latent space. We show that the learned latent space contains a well-defined semantic structure, implying that we can perform calculations in the space of retinal images, e.g., smoothly interpolating new data points between two retinal images. Visual and quantitative results demonstrate that the synthesized images are substantially different from those in the training set, while being also anatomically consistent and displaying a reasonable visual quality.

  17. Pericytes derived from adipose-derived stem cells protect against retinal vasculopathy.

    Directory of Open Access Journals (Sweden)

    Thomas A Mendel

    Full Text Available Retinal vasculopathies, including diabetic retinopathy (DR, threaten the vision of over 100 million people. Retinal pericytes are critical for microvascular control, supporting retinal endothelial cells via direct contact and paracrine mechanisms. With pericyte death or loss, endothelial dysfunction ensues, resulting in hypoxic insult, pathologic angiogenesis, and ultimately blindness. Adipose-derived stem cells (ASCs differentiate into pericytes, suggesting they may be useful as a protective and regenerative cellular therapy for retinal vascular disease. In this study, we examine the ability of ASCs to differentiate into pericytes that can stabilize retinal vessels in multiple pre-clinical models of retinal vasculopathy.We found that ASCs express pericyte-specific markers in vitro. When injected intravitreally into the murine eye subjected to oxygen-induced retinopathy (OIR, ASCs were capable of migrating to and integrating with the retinal vasculature. Integrated ASCs maintained marker expression and pericyte-like morphology in vivo for at least 2 months. ASCs injected after OIR vessel destabilization and ablation enhanced vessel regrowth (16% reduction in avascular area. ASCs injected intravitreally before OIR vessel destabilization prevented retinal capillary dropout (53% reduction. Treatment of ASCs with transforming growth factor beta (TGF-β1 enhanced hASC pericyte function, in a manner similar to native retinal pericytes, with increased marker expression of smooth muscle actin, cellular contractility, endothelial stabilization, and microvascular protection in OIR. Finally, injected ASCs prevented capillary loss in the diabetic retinopathic Akimba mouse (79% reduction 2 months after injection.ASC-derived pericytes can integrate with retinal vasculature, adopting both pericyte morphology and marker expression, and provide functional vascular protection in multiple murine models of retinal vasculopathy. The pericyte phenotype demonstrated

  18. 3D Reconstruction of the Retinal Arterial Tree Using Subject-Specific Fundus Images

    Science.gov (United States)

    Liu, D.; Wood, N. B.; Xu, X. Y.; Witt, N.; Hughes, A. D.; Samcg, Thom

    Systemic diseases, such as hypertension and diabetes, are associated with changes in the retinal microvasculature. Although a number of studies have been performed on the quantitative assessment of the geometrical patterns of the retinal vasculature, previous work has been confined to 2 dimensional (2D) analyses. In this paper, we present an approach to obtain a 3D reconstruction of the retinal arteries from a pair of 2D retinal images acquired in vivo. A simple essential matrix based self-calibration approach was employed for the "fundus camera-eye" system. Vessel segmentation was performed using a semi-automatic approach and correspondence between points from different images was calculated. The results of 3D reconstruction show the centreline of retinal vessels and their 3D curvature clearly. Three-dimensional reconstruction of the retinal vessels is feasible and may be useful in future studies of the retinal vasculature in disease.

  19. Plastic roles of pericytes in the blood-retinal barrier.

    Science.gov (United States)

    Park, Do Young; Lee, Junyeop; Kim, Jaeryung; Kim, Kangsan; Hong, Seonpyo; Han, Sangyeul; Kubota, Yoshiaki; Augustin, Hellmut G; Ding, Lei; Kim, Jin Woo; Kim, Hail; He, Yulong; Adams, Ralf H; Koh, Gou Young

    2017-05-16

    The blood-retinal barrier (BRB) consists of tightly interconnected capillary endothelial cells covered with pericytes and glia, but the role of the pericytes in BRB regulation is not fully understood. Here, we show that platelet-derived growth factor (PDGF)-B/PDGF receptor beta (PDGFRβ) signalling is critical in formation and maturation of BRB through active recruitment of pericytes onto growing retinal vessels. Impaired pericyte recruitment to the vessels shows multiple vascular hallmarks of diabetic retinopathy (DR) due to BRB disruption. However, PDGF-B/PDGFRβ signalling is expendable for maintaining BRB integrity in adult mice. Although selective pericyte loss in stable adult retinal vessels surprisingly does not cause BRB disintegration, it sensitizes retinal vascular endothelial cells (ECs) to VEGF-A, leading to upregulation of angiopoietin-2 (Ang2) in ECs through FOXO1 activation and triggering a positive feedback that resembles the pathogenesis of DR. Accordingly, either blocking Ang2 or activating Tie2 greatly attenuates BRB breakdown, suggesting potential therapeutic approaches to reduce retinal damages upon DR progression.

  20. Correlation between Retinal Vessel Calibre and Neurodegeneration in Patients with Type 2 Diabetes Mellitus in the European Consortium for the Early Treatment of Diabetic Retinopathy (EUROCONDOR)

    DEFF Research Database (Denmark)

    Frydkjaer-Olsen, Ulrik; Soegaard Hansen, Rasmus; Simó, Rafael

    2016-01-01

    .04). In a multivariable linear regression model, CRAE was associated with macular ganglion cell layer thickness (coefficient 0.27 per micrometre, p correlated with macular retinal thickness (coefficient -0.07 per micrometre, p = 0.04) and retinal nerve fibre layer thickness at the optic disc......PURPOSE: To investigate the correlation between retinal vessel calibre and measurements of neurodegeneration in patients with type 2 diabetes (T2D) and no or early diabetic retinopathy (DR). METHODS: Baseline data on 440 patients with T2D from the EUROCONDOR clinical trial were used. DR was graded...... (coefficient 0.32 per micrometre, p

  1. Automatic detection of retinal anatomy to assist diabetic retinopathy screening

    Science.gov (United States)

    Fleming, Alan D.; Goatman, Keith A.; Philip, Sam; Olson, John A.; Sharp, Peter F.

    2007-01-01

    Screening programmes for diabetic retinopathy are being introduced in the United Kingdom and elsewhere. These require large numbers of retinal images to be manually graded for the presence of disease. Automation of image grading would have a number of benefits. However, an important prerequisite for automation is the accurate location of the main anatomical features in the image, notably the optic disc and the fovea. The locations of these features are necessary so that lesion significance, image field of view and image clarity can be assessed. This paper describes methods for the robust location of the optic disc and fovea. The elliptical form of the major retinal blood vessels is used to obtain approximate locations, which are refined based on the circular edge of the optic disc and the local darkening at the fovea. The methods have been tested on 1056 sequential images from a retinal screening programme. Positional accuracy was better than 0.5 of a disc diameter in 98.4% of cases for optic disc location, and in 96.5% of cases for fovea location. The methods are sufficiently accurate to form an important and effective component of an automated image grading system for diabetic retinopathy screening.

  2. Automatic detection of retinal anatomy to assist diabetic retinopathy screening

    Energy Technology Data Exchange (ETDEWEB)

    Fleming, Alan D [Biomedical Physics, University of Aberdeen, Aberdeen, AB25 2ZD (United Kingdom); Goatman, Keith A [Biomedical Physics, University of Aberdeen, Aberdeen, AB25 2ZD (United Kingdom); Philip, Sam [Grampian Diabetes Retinal Screening Programme, Woolmanhill Hospital, Aberdeen, AB25 1LD (United Kingdom); Olson, John A [Grampian Diabetes Retinal Screening Programme, Woolmanhill Hospital, Aberdeen, AB25 1LD (United Kingdom); Sharp, Peter F [Biomedical Physics, University of Aberdeen, Aberdeen, AB25 2ZD (United Kingdom)

    2007-01-21

    Screening programmes for diabetic retinopathy are being introduced in the United Kingdom and elsewhere. These require large numbers of retinal images to be manually graded for the presence of disease. Automation of image grading would have a number of benefits. However, an important prerequisite for automation is the accurate location of the main anatomical features in the image, notably the optic disc and the fovea. The locations of these features are necessary so that lesion significance, image field of view and image clarity can be assessed. This paper describes methods for the robust location of the optic disc and fovea. The elliptical form of the major retinal blood vessels is used to obtain approximate locations, which are refined based on the circular edge of the optic disc and the local darkening at the fovea. The methods have been tested on 1056 sequential images from a retinal screening programme. Positional accuracy was better than 0.5 of a disc diameter in 98.4% of cases for optic disc location, and in 96.5% of cases for fovea location. The methods are sufficiently accurate to form an important and effective component of an automated image grading system for diabetic retinopathy screening.

  3. Automatic detection of retinal anatomy to assist diabetic retinopathy screening

    International Nuclear Information System (INIS)

    Fleming, Alan D; Goatman, Keith A; Philip, Sam; Olson, John A; Sharp, Peter F

    2007-01-01

    Screening programmes for diabetic retinopathy are being introduced in the United Kingdom and elsewhere. These require large numbers of retinal images to be manually graded for the presence of disease. Automation of image grading would have a number of benefits. However, an important prerequisite for automation is the accurate location of the main anatomical features in the image, notably the optic disc and the fovea. The locations of these features are necessary so that lesion significance, image field of view and image clarity can be assessed. This paper describes methods for the robust location of the optic disc and fovea. The elliptical form of the major retinal blood vessels is used to obtain approximate locations, which are refined based on the circular edge of the optic disc and the local darkening at the fovea. The methods have been tested on 1056 sequential images from a retinal screening programme. Positional accuracy was better than 0.5 of a disc diameter in 98.4% of cases for optic disc location, and in 96.5% of cases for fovea location. The methods are sufficiently accurate to form an important and effective component of an automated image grading system for diabetic retinopathy screening

  4. Automatic detection of retinal anatomy to assist diabetic retinopathy screening.

    Science.gov (United States)

    Fleming, Alan D; Goatman, Keith A; Philip, Sam; Olson, John A; Sharp, Peter F

    2007-01-21

    Screening programmes for diabetic retinopathy are being introduced in the United Kingdom and elsewhere. These require large numbers of retinal images to be manually graded for the presence of disease. Automation of image grading would have a number of benefits. However, an important prerequisite for automation is the accurate location of the main anatomical features in the image, notably the optic disc and the fovea. The locations of these features are necessary so that lesion significance, image field of view and image clarity can be assessed. This paper describes methods for the robust location of the optic disc and fovea. The elliptical form of the major retinal blood vessels is used to obtain approximate locations, which are refined based on the circular edge of the optic disc and the local darkening at the fovea. The methods have been tested on 1056 sequential images from a retinal screening programme. Positional accuracy was better than 0.5 of a disc diameter in 98.4% of cases for optic disc location, and in 96.5% of cases for fovea location. The methods are sufficiently accurate to form an important and effective component of an automated image grading system for diabetic retinopathy screening.

  5. A study of magnification effect to precision of computerized diameter measurement of a 3-mm vessel phantom in cineangiograms

    International Nuclear Information System (INIS)

    Yanagihara, Yoshio; Sugahara, Tetsuo; Sugimoto, Naozou; Fukunishi, Yasunobu.

    1994-01-01

    To estimate influence of magnification on digitizing to Precision of computerized measurement of coronary vessel diameter, the two measurement methods, i.e., a combined filter and Entropy filter, were applied to magnified images (x1-x6) of cineangiograms radiographed for a 3-mm vessel phantom. In conclusion, the desirable precision in clinical use, we thought, was obtainable at the magnification of x3 to x4. (author)

  6. Long-term changes in retinal vascular diameter and cognitive impairment in type 1 diabetes.

    Science.gov (United States)

    Nunley, Karen A; Metti, Andrea L; Klein, Ronald; Klein, Barbara E; Saxton, Judith A; Orchard, Trevor J; Costacou, Tina; Aizenstein, Howard J; Rosano, Caterina

    2018-05-01

    To assess associations between cognitive impairment and longitudinal changes in retinal microvasculature, over 18 years, in adults with type 1 diabetes. Participants of the Pittsburgh Epidemiology of Diabetes Complications Study received ≥3 fundus photographs between baseline (1986-1988) and time of cognitive assessment (2010-2015: N = 119; 52% male; mean age and type 1 diabetes duration 43 and 34 years, respectively). Central retinal arteriolar equivalent and central retinal venular equivalent were estimated via computer-based methods; overall magnitude and speed of narrowing were quantified as cumulative average and slope, respectively. Median regression models estimated associations of central retinal arteriolar equivalent and central retinal venular equivalent measures with cognitive impairment status, adjusted for type 1 diabetes duration. Interactions with HbA1c, proliferative retinopathy and white matter hyperintensities were assessed. Compared with participants without cognitive impairment, those with clinically relevant cognitive impairment experienced 1.8% greater and 31.1% faster central retinal arteriolar equivalent narrowing during prior years (t = -2.93, p = 0.004 and t = -3.97, p impairment. Long-term arterial retinal changes could indicate type 1 diabetes-related cognitive impairment. Studies examining longitudinal central retinal arteriolar equivalent changes as early biomarkers of cognitive impairment risk are warranted.

  7. An automated retinal imaging method for the early diagnosis of diabetic retinopathy.

    Science.gov (United States)

    Franklin, S Wilfred; Rajan, S Edward

    2013-01-01

    Diabetic retinopathy is a microvascular complication of long-term diabetes and is the major cause for eyesight loss due to changes in blood vessels of the retina. Major vision loss due to diabetic retinopathy is highly preventable with regular screening and timely intervention at the earlier stages. Retinal blood vessel segmentation methods help to identify the successive stages of such sight threatening diseases like diabetes. To develop and test a novel retinal imaging method which segments the blood vessels automatically from retinal images, which helps the ophthalmologists in the diagnosis and follow-up of diabetic retinopathy. This method segments each image pixel as vessel or nonvessel, which in turn, used for automatic recognition of the vasculature in retinal images. Retinal blood vessels were identified by means of a multilayer perceptron neural network, for which the inputs were derived from the Gabor and moment invariants-based features. Back propagation algorithm, which provides an efficient technique to change the weights in a feed forward network, is utilized in our method. Quantitative results of sensitivity, specificity and predictive values were obtained in our method and the measured accuracy of our segmentation algorithm was 95.3%, which is better than that presented by state-of-the-art approaches. The evaluation procedure used and the demonstrated effectiveness of our automated retinal imaging method proves itself as the most powerful tool to diagnose diabetic retinopathy in the earlier stages.

  8. Feasibility study on retinal vascular bypass surgery in isolated arterially perfused caprine eye model

    Science.gov (United States)

    Chen, Y; Wu, W; Zhang, X; Fan, W; Shen, L

    2011-01-01

    Purpose To investigate the feasibility of bypassing occluded segments of retinal venous main vessels in isolated, arterially perfused caprine eyes via the closed-sky vitrectomy approach using keratoprosthesis. Methods Isolated caprine eyes were used in this study. For each eye, the retinal vessel was perfused by Krebs solution via ophthalmic artery, and pars plana vitrectomy was performed using temporary keratoprosthesis. All retinal micro-vascular maneuvers were performed in a closed-sky eyeball. The main retinal vein was blocked by endodiathermy at the site of the vessel's first branching. Two openings, several millimeters apart, were created by vascular punctures in both the main vein and its branch vein wall straddling the induced occluded segment. Catheterization was achieved using a flexible polyimide tube, with each end inserted into the vessel wall opening. A sealed connection between the vessel and the tube was obtained by endodiathermy. Bypass of the occluded retinal vein segment was thus achieved, and the patency of this vascular bypass was confirmed by intravascular staining. Results Puncturing, catheterization, and endodiathermy were viable by closed-sky approach using keratoprosthesis. Bypassing of the occluded retinal main vein segment was accomplished with the combination of these maneuvers. Good results were obtained in 23 of 38 (60%) caprine eyes. Conclusions This study demonstrated that bypassing the occluded segment of retinal main vein can be successfully performed in a closed-sky eyeball model of isolated, arterially perfused caprine eye. This early work indicated that the more advanced retinal vascular bypass surgery in in vivo eye may be feasible in the future. PMID:21921946

  9. Influence of transverse mode on retinal spot size and retinal injury effect: A theoretical analysis on 532-nm laser

    Directory of Open Access Journals (Sweden)

    Jia-Rui Wang

    2014-05-01

    Full Text Available The fundamental transverse mode (TEM00 is preferable for experimental and theoretical study on the laser-induced retinal injury effect, for it can produce the minimal retinal image and establish the most strict laser safety standards. But actually lasers with higher order mode were frequently used in both earlier and recent studies. Generally higher order mode leads to larger retinal spot size and so higher damage threshold, but there are few quantitative analyses on this problem. In this paper, a four-surface schematic eye model is established for human and macaque. The propagation of 532-nm laser in schematic eye is analyzed by the ABCD law of Gaussian optics. It is shown that retinal spot size increases with laser transverse mode order. For relative lower mode order, the retinal spot diameter will not exceed the minimum laser-induced retinal lesion (25 ~ 30 μm in diameter, and so has little effect on retinal damage threshold. While for higher order mode, the larger retinal spot requires more energy to induce injury and so the damage threshold increases. When beam divergence is lowered, the retinal spot size decreases correspondingly, so the effect of mode order can be compensated. The retinal spot size of macaque is slightly smaller than that of human and the ratio between them is independent of mode order. We conclude that the laser mode order has significant influence on retinal spot size but limited influence on the retinal injury effect.

  10. Applying photoacoustics to quantification of melanin concentration in retinal pigment epithelium (Conference Presentation)

    Science.gov (United States)

    Shu, Xiao; Zhang, Hao F.; Liu, Wenzhong

    2016-03-01

    The melanin in the retinal pigment epithelium (RPE) protects retina and other ocular tissues by photo-screening and acting as antioxidant and free radical scavenger. It helps maintain normal visual functions since human eye is subjected to lifelong high oxygen stress and photon exposure. Loss of the RPE melanin weakens the protection mechanism and jeopardizes ocular health. Local decrease in the RPE melanin concentration is believed to be both a cause and a sign of early-stage age-related macular degeneration (AMD), the leading blinding disease in developed world. Current technology cannot quantitatively measure the RPE melanin concentration which might be a promising marker in early AMD screening. Photoacoustic ophthalmoscopy (PAOM), as an emerging optical absorption-based imaging technology, can potentially be applied to measure the RPE melanin concentration if the dependence of the detectable photoacoustic (PA) signal amplitudes on the RPE melanin concentrations is verified. In this study, we tested the feasibility of using PA signal ratio from RPE melanin and the nearby retinal blood vessels as an indicator of the RPE melanin variation. A novel whole eye optical model was designed and Monte Carlo modeling of light (MCML) was employed. We examined the influences on quantification from PAOM axial resolution, the depth and diameter of the retinal blood vessel, and the RPE thickness. The results show that the scheme is robust to individual histological and illumination variations. This study suggests that PAOM is capable of quantitatively measuring the RPE melanin concentration in vivo.

  11. A consonant construction of the hyaloid and retinal vascular systems by the angiogenic process.

    Science.gov (United States)

    Gergely, K; Gerinec, A

    2011-01-01

    There has been much debate as to whether the retinal vasculature forms by angiogenesis or vasculogenesis, thus angiogenesis is now accepted. We suppose that signals necessary for proper localization and development of the hyaloid and retinal vascular systems are already in place prior to the time at which these systems are developed. The remarkable conservation of vascular patterning suggests that specific genetic programs coordinate its formation. Evidence for a genetic program comes particularly from the characterization of gene-targeted mice and mutational analysis in zebrafish, but the exact genetic pathways remain poorly defined. Considering all the things from the aspect of angiogenesis significant differences exist between the mentioned vascular systems only in their lifetime (a) and location (b): (a) The hyaloid vasculature is a complex of transient intraocular vessels, while the retinal vessels are adapted for the whole life. (b) The hyaloid system fills the interior of the optic cup and this way "occupies" three-dimensional space while the distribution of the retinal vessels is relatively planar (two-dimensional) in the retina. We assume that retinal vessels are "built" in the same manner as the hyaloid vasculature and the outcomes at the embryological, histological, cellular and molecular levels confirm it. We show a consonant construction of both systems. The human organism does not have any rational reason to build up one system (i.e. the hyaloid vasculature) by angiogenesis and practically the same system (i.e. the retinal vessels) by another, de novo process, in the eye. It would be a waste of energy and various essential molecules. Thus, it seems that the retinal vascular system is an advanced copy of the hyaloid vessels (Tab. 1, Ref. 143).

  12. An Unusual Case of Extensive Lattice Degeneration and Retinal Detachment

    OpenAIRE

    Mathew, David J.; Sarma, Saurabh Kumar; Basaiawmoit, Jennifer V.

    2016-01-01

    Lattice degeneration of the retina is not infrequently encountered on a dilated retinal examination and many of them do not need any intervention. We report a case of atypical lattice degeneration variant with peripheral retinal detachment. An asymptomatic 35-year-old lady with minimal refractive error was found to have extensive lattice degeneration, peripheral retinal detachment and fibrotic changes peripherally with elevation of retinal vessels on dilated retinal examination. There were al...

  13. A new retinal vessel tracking method based on orientation scores

    NARCIS (Netherlands)

    Bekkers, E.J.; Duits, R.; Haar Romeny, ter B.M.; Berendschot, T.T.J.M.

    2012-01-01

    The retinal vasculature is the only part of the body's circulatory system that can be observed non-invasively. A large variety of diseases affect the vasculature, in ways that may cause geometrical and functional changes. Retinal images are therefore not only suitable for investigation of ocular

  14. Retinal Photoreceptors and Microvascular Changes in Prediabetes Measured with Adaptive Optics (rtx1™: A Case-Control Study

    Directory of Open Access Journals (Sweden)

    Anna Zaleska-Żmijewska

    2017-01-01

    Full Text Available Background. Patients with prediabetes are at risk for diabetes, cardiovascular events, and microvascular complications. The rtx1 (Imagine Eyes, France permits early detection of changes in the retinal photoreceptors and vessels. Objective. Cone parameters and retinal microvasculature were analyzed with the rtx1 in 12 prediabetic patients and 22 healthy subjects. The analysis was based on cone density (DM, interphotoreceptor distance (SM, cone packing regularity, and retinal vessel parameters: wall thickness, lumen diameter (LD, wall-to-lumen ratio (WLR, and cross-sectional area of the vascular wall. Results. DM in the prediabetic group was not significantly lower than that in the control group (18,935 ± 1713 cells/mm2 and 19,900 ± 2375 cells/mm2, respectively; p=0.0928. The LD and WLR means differed significantly between the prediabetic and the control groups (LD 94.3 ± 10.9 versus 101.2 ± 15, p=0.022; WLR 0.29 ± 0.05 versus 0.22 ± 0.03, p<0.05. A multivariate regression analysis showed that the WLR was significantly correlated with BMI and total cholesterol. Conclusions. Abnormalities found in rtx1 examinations indicated early signs of arteriolar dysfunction, prior to impaired glucose tolerance progressing to diabetes. The rtx1 retinal image analysis offers noninvasive measurement of early changes in the vasculature that routine clinical examination cannot detect.

  15. Long-term consequences of developmental vascular defects on retinal vessel homeostasis and function in a mouse model of Norrie disease.

    Science.gov (United States)

    Beck, Susanne C; Feng, Yuxi; Sothilingam, Vithiyanjali; Garcia Garrido, Marina; Tanimoto, Naoyuki; Acar, Niyazi; Shan, Shenliang; Seebauer, Britta; Berger, Wolfgang; Hammes, Hans-Peter; Seeliger, Mathias W

    2017-01-01

    Loss of Norrin signalling due to mutations in the Norrie disease pseudoglioma gene causes severe vascular defects in the retina, leading to visual impairment and ultimately blindness. While the emphasis of experimental work so far was on the developmental period, we focus here on disease mechanisms that induce progression into severe adult disease. The goal of this study was the comprehensive analysis of the long-term effects of the absence of Norrin on vascular homeostasis and retinal function. In a mouse model of Norrie disease retinal vascular morphology and integrity were studied by means of in vivo angiography; the vascular constituents were assessed in detailed histological analyses using quantitative retinal morphometry. Finally, electroretinographic analyses were performed to assess the retinal function in adult Norrin deficient animals. We could show that the primary developmental defects not only persisted but developed into further vascular abnormalities and microangiopathies. In particular, the overall vessel homeostasis, the vascular integrity, and also the cellular constituents of the vascular wall were affected in the adult Norrin deficient retina. Moreover, functional analyses indicated to persistent hypoxia in the neural retina which was suggested as one of the major driving forces of disease progression. In summary, our data provide evidence that the key to adult Norrie disease are ongoing vascular modifications, driven by the persistent hypoxic conditions, which are ineffective to compensate for the primary Norrin-dependent defects.

  16. Effect of doxycycline vs placebo on retinal function and diabetic retinopathy progression in patients with severe nonproliferative or non-high-risk proliferative diabetic retinopathy

    DEFF Research Database (Denmark)

    Scott, Ingrid U; Jackson, Gregory R; Quillen, David A

    2014-01-01

    IMPORTANCE: Inflammation may contribute to the pathogenesis of diabetic retinopathy (DR). OBJECTIVES: To investigate, in a proof-of-concept clinical trial, whether low-dose oral doxycycline monohydrate can (1) slow the deterioration of, or improve, retinal function or (2) induce regression or slow......: We conducted a randomized, double-masked, 24-month proof-of-concept clinical trial. Thirty patients (from hospital-based retina practices) with 1 or more eyes with severe NPDR or PDR less than Early Treatment Diabetic Retinopathy Study-defined high-risk PDR. INTERVENTIONS: Patients were randomized...... adaptation, visual acuity, and quality of life) and anatomic factors (Early Treatment Diabetic Retinopathy Study DR severity level, area of retinal thickening, central macular thickness, macular volume, and retinal vessel diameters). RESULTS: From baseline to month 24, mean FDP foveal sensitivity decreased...

  17. The relationship of flow velocities to vessel diameters differs between extracranial carotid and vertebral arteries of stroke patients.

    Science.gov (United States)

    Owolabi, Mayowa O; Agunloye, Atinuke M; Ogunniyi, Adesola

    2014-01-01

    Chronic changes in flow rate through arteries produce adjustment of arterial diameters. We compared the relationship between flow velocity and diameter in the carotid and in the vertebral arteries of stroke patients. Using triplex ultrasonography, the internal diameter and flow velocities of the common carotid, internal carotid, and vertebral arteries of 176 consecutive stroke patients were measured. Correlations were examined with Pearson's statistics at an alpha level of 0.05. Mean age of the patients was 59.3 ± 12 years, and 66% had cerebral infarcts. Diameter and blood flow velocities showed significant negative correlations (-0.115 ≥ r ≥ -0.382) in the carotid arteries on both sides, but positive correlations (0.211 ≤ r ≤ 0.320) in the vertebral arteries, even after controlling for age, gender, and blood pressure. Our study demonstrated different diameter/flow relationships in the carotid and the vertebral arteries of stroke patients, which may suggest pathologic changes in the adaptive processes governing vessel diameter and growth, especially in the carotid arteries. Copyright © 2013 Wiley Periodicals, Inc.

  18. Retinal vessel calibre and micro- and macrovascular complications in type 1 diabetes

    DEFF Research Database (Denmark)

    Grauslund, J; Hodgson, L; Kawasaki, R

    2009-01-01

    AIMS/HYPOTHESIS: The purpose of the study was to evaluate the association between retinal vascular calibre and micro- and macrovascular complications in a population-based cohort of Danish type 1 diabetic patients. METHODS: This was a cross-sectional study of 208 long-surviving type 1 diabetic...... and a standardised protocol. Associations between retinal vascular calibre and micro- and macrovascular complications were examined after adjusting for confounding clinical characteristics. RESULTS: Retinal photographs were gradable for 188 of 208 patients (90.3%). The median age and duration of diabetes...... in CRAE), but not neuropathy (OR 1.10, 95% CI 0.70-1.71, per SD decrease in CRAE). Retinal venular calibre was not associated with any micro- or macrovascular complications. CONCLUSIONS/INTERPRETATION: In type 1 diabetic patients, retinal arteriolar narrowing is associated with nephropathy...

  19. Long-term consequences of developmental vascular defects on retinal vessel homeostasis and function in a mouse model of Norrie disease.

    Directory of Open Access Journals (Sweden)

    Susanne C Beck

    Full Text Available Loss of Norrin signalling due to mutations in the Norrie disease pseudoglioma gene causes severe vascular defects in the retina, leading to visual impairment and ultimately blindness. While the emphasis of experimental work so far was on the developmental period, we focus here on disease mechanisms that induce progression into severe adult disease. The goal of this study was the comprehensive analysis of the long-term effects of the absence of Norrin on vascular homeostasis and retinal function. In a mouse model of Norrie disease retinal vascular morphology and integrity were studied by means of in vivo angiography; the vascular constituents were assessed in detailed histological analyses using quantitative retinal morphometry. Finally, electroretinographic analyses were performed to assess the retinal function in adult Norrin deficient animals. We could show that the primary developmental defects not only persisted but developed into further vascular abnormalities and microangiopathies. In particular, the overall vessel homeostasis, the vascular integrity, and also the cellular constituents of the vascular wall were affected in the adult Norrin deficient retina. Moreover, functional analyses indicated to persistent hypoxia in the neural retina which was suggested as one of the major driving forces of disease progression. In summary, our data provide evidence that the key to adult Norrie disease are ongoing vascular modifications, driven by the persistent hypoxic conditions, which are ineffective to compensate for the primary Norrin-dependent defects.

  20. Results of laser treatment for sub-retinal neovascular membranes

    African Journals Online (AJOL)

    1990-09-01

    Sep 1, 1990 ... haemonhagic detachment of the retinal pigment epithelium and sensory· retina produced by exudation from these new vessels.I-l This exudative and sometimes haemorrhagic process often leads to severe and permanent loss of central vision because of sub-retinal fibrovascular organisation.2 Progressive.

  1. Optical coherence tomography angiography indicates associations of the retinal vascular network and disease activity in multiple sclerosis.

    Science.gov (United States)

    Feucht, Nikolaus; Maier, Mathias; Lepennetier, Gildas; Pettenkofer, Moritz; Wetzlmair, Carmen; Daltrozzo, Tanja; Scherm, Pauline; Zimmer, Claus; Hoshi, Muna-Miriam; Hemmer, Bernhard; Korn, Thomas; Knier, Benjamin

    2018-01-01

    Patients with multiple sclerosis (MS) and clinically isolated syndrome (CIS) may show alterations of retinal layer architecture as measured by optical coherence tomography. Little is known about changes in the retinal vascular network during MS. To characterize retinal vessel structures in patients with MS and CIS and to test for associations with MS disease activity. In all, 42 patients with MS or CIS and 50 healthy controls underwent retinal optical coherence tomography angiography (OCT-A) with analysis of the superficial and deep vascular plexuses and the choriocapillaries. We tested OCT-A parameters for associations with retinal layer volumes, history of optic neuritis (ON), and the retrospective disease activity. Inner retinal layer volumes correlated positively with the density of both the superficial and deep vascular plexuses. Eyes of MS/CIS patients with a history of ON revealed reduced vessel densities of the superficial and deep vascular plexuses as compared to healthy controls. Higher choriocapillary vessel densities were associated with ongoing inflammatory disease activity during 24 months prior to OCT-A examination in MS and CIS patients. Optic neuritis is associated with rarefaction of the superficial and deep retinal vessels. Alterations of the choriocapillaries might be linked to disease activity in MS.

  2. Porous hybrid structures based on P(DLLA-co-TMC) and collagen for tissue engineering of small-diameter blood vessels

    NARCIS (Netherlands)

    Buttafoco, L.; Boks, Niels P.; Engbers-Buijtenhuijs, P.; Grijpma, Dirk W.; Poot, Andreas A.; Dijkstra, Pieter J.; Vermes, I.; Feijen, Jan

    2006-01-01

    Poly (D,L-lactide)-7co-(1,3-trimethylene carbonate) [P(DLLA-co-TMC)] (83 mol % DLLA) was used to produce matrices suitable for tissue engineering of small-diameter blood vessels. The copolymer was processed into tubular structures with a porosity of 98% by melt spinning and fiber winding, thus

  3. Retinal expression, regulation, and functional bioactivity of prostacyclin-stimulating factor

    OpenAIRE

    Hata, Yasuaki; Clermont, Allen Charles; Yamauchi, Teruaki; Pierce, Eric Adam; Suzuma, Izumi; Kagokawa, Hiroyuki; Yoshikawa, Hiroshi; Robinson, Gregory S.; Ishibashi, Tatsuro; Hashimoto, Toshihiko; Umeda, Fumio; Bursell, Sven E.; Aiello, Lloyd Paul

    2000-01-01

    Prostacyclin-stimulating factor (PSF) acts on vascular endothelial cells to stimulate the synthesis of the vasodilatory molecule prostacyclin (PGI2). We have examined the expression, regulation, and hemodynamic bioactivity of PSF both in whole retina and in cultured cells derived from this tissue. PSF was expressed in all retinal cell types examined in vitro, but immunohistochemical analysis revealed PSF mainly associated with retinal vessels. PSF expression was constitutive in retinal pericy...

  4. Registration of retinal sequences from new video-ophthalmoscopic camera.

    Science.gov (United States)

    Kolar, Radim; Tornow, Ralf P; Odstrcilik, Jan; Liberdova, Ivana

    2016-05-20

    Analysis of fast temporal changes on retinas has become an important part of diagnostic video-ophthalmology. It enables investigation of the hemodynamic processes in retinal tissue, e.g. blood-vessel diameter changes as a result of blood-pressure variation, spontaneous venous pulsation influenced by intracranial-intraocular pressure difference, blood-volume changes as a result of changes in light reflection from retinal tissue, and blood flow using laser speckle contrast imaging. For such applications, image registration of the recorded sequence must be performed. Here we use a new non-mydriatic video-ophthalmoscope for simple and fast acquisition of low SNR retinal sequences. We introduce a novel, two-step approach for fast image registration. The phase correlation in the first stage removes large eye movements. Lucas-Kanade tracking in the second stage removes small eye movements. We propose robust adaptive selection of the tracking points, which is the most important part of tracking-based approaches. We also describe a method for quantitative evaluation of the registration results, based on vascular tree intensity profiles. The achieved registration error evaluated on 23 sequences (5840 frames) is 0.78 ± 0.67 pixels inside the optic disc and 1.39 ± 0.63 pixels outside the optic disc. We compared the results with the commonly used approaches based on Lucas-Kanade tracking and scale-invariant feature transform, which achieved worse results. The proposed method can efficiently correct particular frames of retinal sequences for shift and rotation. The registration results for each frame (shift in X and Y direction and eye rotation) can also be used for eye-movement evaluation during single-spot fixation tasks.

  5. Clinicopathologic correlation of argon laser photocoagulation of retinal angiomas in a patient with von Hippel-Lindau disease followed for more than 20 years.

    Science.gov (United States)

    Rosa, R H; Goldberg, M F; Green, W R

    1996-01-01

    The authors review the histopathologic findings in the eyes of a patient with multiple retinal angiomas and von Hippel-Lindau disease, who underwent treatment with argon laser photocoagulation with follow-up of more than 20 years. The patient was studied ophthalmoscopically and by fluorescein angiography before and after argon laser photocoagulation of retinal angiomas. The eyes were obtained postmortem, and the central portion of the right eye, including the macula and optic nerve head, was sectioned serially for light microscopy. The pupil-optic nerve segment of the left eye was step-sectioned serially for light microscopy. Histopathologic study of the right eye disclosed mild cystoid macular edema and focal areas of exudation in the midperiphery possibly secondary to irradiation of the head. A 1.5 x 0.3-mm area of residual angioma was present in the nasal peripapillary retina. Superotemporally, four chorioretinal scars were present in one photocoagulated area. These scars were composed of dense fibrous tissue with vascularization and variable retinal pigment epithelium hyperplasia. Large, nonangiomatous vessels within each of the scars were continuous with other retinal vessels. Inferotemporally, two chorioretinal scars were present in one photocoagulated area. Histopathologically, these scars were similar to the superotemporal scars, except that no patent retinal vessels traversed the inferotemporal scars. Neovascularization of the retina was associated with one superotemporal and one inferotemporal scar. No residual angiomatous tissue was present in the supero- or inferotemporal areas. Histopathologic examination of the left eye disclosed extensive vitreous organization and periretinal fibrovascular proliferation, extensive gliosis of the retina, and a 4.5 x 2-mm schisis cavity filled with fibrinous exudate. Three angiomas with variable fibrosis were present in the left eye. Despite a poor clinical course in one eye treated with xenon arc photocoagulation

  6. Retinal oxygen saturation before and after glaucoma surgery.

    Science.gov (United States)

    Nitta, Eri; Hirooka, Kazuyuki; Shimazaki, Takeru; Sato, Shino; Ukegawa, Kaori; Nakano, Yuki; Tsujikawa, Akitaka

    2017-08-01

    This study compared retinal vessel oxygen saturation before and after glaucoma surgery. Retinal oxygen saturation in glaucoma patients was measured using a non-invasive spectrophotometric retinal oximeter. Adequate image quality was found in 49 of the 108 consecutive glaucoma patients recruited, with 30 undergoing trabeculectomy, 11 EX-PRESS and eight trabeculotomy. Retinal oxygen saturation measurements in the retinal arterioles and venules were performed at 1 day prior to and at approximately 10 days after surgery. Statistical analysis was performed using a Student's t-test. After glaucoma surgery, intraocular pressure (IOP) decreased from 19.8 ± 7.7 mmHg to 9.0 ± 5.7 mmHg (p glaucoma surgery had an effect on the retinal venous oxygen saturation. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  7. Pharmacologic Activation of Wnt Signaling by Lithium Normalizes Retinal Vasculature in a Murine Model of Familial Exudative Vitreoretinopathy.

    Science.gov (United States)

    Wang, Zhongxiao; Liu, Chi-Hsiu; Sun, Ye; Gong, Yan; Favazza, Tara L; Morss, Peyton C; Saba, Nicholas J; Fredrick, Thomas W; He, Xi; Akula, James D; Chen, Jing

    2016-10-01

    Familial exudative vitreoretinopathy (FEVR) is characterized by delayed retinal vascular development, which promotes hypoxia-induced pathologic vessels. In severe cases FEVR may lead to retinal detachment and visual impairment. Genetic studies linked FEVR with mutations in Wnt signaling ligand or receptors, including low-density lipoprotein receptor-related protein 5 (LRP5) gene. Here, we investigated ocular pathologies in a Lrp5 knockout (Lrp5(-/-)) mouse model of FEVR and explored whether treatment with a pharmacologic Wnt activator lithium could bypass the genetic defects, thereby protecting against eye pathologies. Lrp5(-/-) mice displayed significantly delayed retinal vascular development, absence of deep layer retinal vessels, leading to increased levels of vascular endothelial growth factor and subsequent pathologic glomeruloid vessels, as well as decreased inner retinal visual function. Lithium treatment in Lrp5(-/-) mice significantly restored the delayed development of retinal vasculature and the intralaminar capillary networks, suppressed formation of pathologic glomeruloid structures, and promoted hyaloid vessel regression. Moreover, lithium treatment partially rescued inner-retinal visual function and increased retinal thickness. These protective effects of lithium were largely mediated through restoration of canonical Wnt signaling in Lrp5(-/-) retina. Lithium treatment also substantially increased vascular tubular formation in LRP5-deficient endothelial cells. These findings suggest that pharmacologic activation of Wnt signaling may help treat ocular pathologies in FEVR and potentially other defective Wnt signaling-related diseases. Copyright © 2016 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  8. Inter-Eye Agreement in Measurement of Retinal Vascular Fractal Dimension in Patients with Type 1 Diabetes Mellitus

    DEFF Research Database (Denmark)

    Pedersen, Knud B; Broe, Rebecca; Grauslund, Jakob

    2016-01-01

    PURPOSE: To investigate inter-eye agreement in retinal vascular fractal dimension (FD) in patients with type 1 diabetes. METHODS: In a cross-sectional study, both eyes were exained in 178 patients with type 1 diabetes. All vessels in a zone 0.5-2.0 disc diameters from the optic disc were traced...... and FD calculated with the box-counting method using SIVA-Fractal semiautomatic software. The modified Early Treatment Diabetic Retinopathy Study (ETDRS) scale was used to grade diabetic retinopathy (DR). Pitman's test of difference in variance was used to calculated inter-eye agreement in FD according...

  9. Retinal Vascular and Oxygen Temporal Dynamic Responses to Light Flicker in Humans.

    Science.gov (United States)

    Felder, Anthony E; Wanek, Justin; Blair, Norman P; Shahidi, Mahnaz

    2017-11-01

    To mathematically model the temporal dynamic responses of retinal vessel diameter (D), oxygen saturation (SO2), and inner retinal oxygen extraction fraction (OEF) to light flicker and to describe their responses to its cessation in humans. In 16 healthy subjects (age: 60 ± 12 years), retinal oximetry was performed before, during, and after light flicker stimulation. At each time point, five metrics were measured: retinal arterial and venous D (DA, DV) and SO2 (SO2A, SO2V), and OEF. Intra- and intersubject variability of metrics was assessed by coefficient of variation of measurements before flicker within and among subjects, respectively. Metrics during flicker were modeled by exponential functions to determine the flicker-induced steady state metric values and the time constants of changes. Metrics after the cessation of flicker were compared to those before flicker. Intra- and intersubject variability for all metrics were less than 6% and 16%, respectively. At the flicker-induced steady state, DA and DV increased by 5%, SO2V increased by 7%, and OEF decreased by 13%. The time constants of DA and DV (14, 15 seconds) were twofold smaller than those of SO2V and OEF (39, 34 seconds). Within 26 seconds after the cessation of flicker, all metrics were not significantly different from before flicker values (P ≥ 0.07). Mathematical modeling revealed considerable differences in the time courses of changes among metrics during flicker, indicating flicker duration should be considered separately for each metric. Future application of this method may be useful to elucidate alterations in temporal dynamic responses to light flicker due to retinal diseases.

  10. Automated vessel shadow segmentation of fovea-centered spectral-domain images from multiple OCT devices

    Science.gov (United States)

    Wu, Jing; Gerendas, Bianca S.; Waldstein, Sebastian M.; Simader, Christian; Schmidt-Erfurth, Ursula

    2014-03-01

    Spectral-domain Optical Coherence Tomography (SD-OCT) is a non-invasive modality for acquiring high reso- lution, three-dimensional (3D) cross sectional volumetric images of the retina and the subretinal layers. SD-OCT also allows the detailed imaging of retinal pathology, aiding clinicians in the diagnosis of sight degrading diseases such as age-related macular degeneration (AMD) and glaucoma.1 Disease diagnosis, assessment, and treatment requires a patient to undergo multiple OCT scans, possibly using different scanning devices, to accurately and precisely gauge disease activity, progression and treatment success. However, the use of OCT imaging devices from different vendors, combined with patient movement may result in poor scan spatial correlation, potentially leading to incorrect patient diagnosis or treatment analysis. Image registration can be used to precisely compare disease states by registering differing 3D scans to one another. In order to align 3D scans from different time- points and vendors using registration, landmarks are required, the most obvious being the retinal vasculature. Presented here is a fully automated cross-vendor method to acquire retina vessel locations for OCT registration from fovea centred 3D SD-OCT scans based on vessel shadows. Noise filtered OCT scans are flattened based on vendor retinal layer segmentation, to extract the retinal pigment epithelium (RPE) layer of the retina. Voxel based layer profile analysis and k-means clustering is used to extract candidate vessel shadow regions from the RPE layer. In conjunction, the extracted RPE layers are combined to generate a projection image featuring all candidate vessel shadows. Image processing methods for vessel segmentation of the OCT constructed projection image are then applied to optimize the accuracy of OCT vessel shadow segmentation through the removal of false positive shadow regions such as those caused by exudates and cysts. Validation of segmented vessel shadows uses

  11. Retinal Oximetry with Scanning Laser Ophthalmoscope in Infants.

    Directory of Open Access Journals (Sweden)

    Wouter B Vehmeijer

    Full Text Available Dual wavelength retinal oximetry has been developed for adults, but is not available for infants. Retinal oximetry may provide insight into the pathophysiology of oxygen-mediated diseases like retinopathy of prematurity. More insight in the oxygen metabolism of the retina in infants may provide valuable clues for better understanding and subsequent prevention or treatment of the disease. The measurements of oxygen saturation are obtained with two fundus images simultaneously captured in two different wavelengths of light. The comparison in light absorption of oxygenated and deoxygenated hemoglobin can be used to estimate the oxygen saturation within the retinal vessels by means of a software algorithm. This study aims to make retinal oximetry available for neonates. The first step towards estimating retinal oxygen saturation is determining the optical density ratio. Therefore, the purpose of this study is to image healthy newborn infants with a scanning laser ophthalmoscope and determine the optical density ratio for retinal oximetry analysis.Images of the retina of full-term healthy infants were obtained with an SLO, Optomap 200Tx (Optos, with two laser wavelengths (532nm and 633nm. The infant lay face down on the lower arm of the parent, while the parent supported the chest and chin with one hand, and stabilized the back with the other hand. No mydriatics or eyelid specula were used during this study. The images were analyzed with modified Oxymap Analyzer software for calculation of the Optical Density Ratio (ODR and vessel width. The ODR is inversely and approximately linearly related to the oxygen saturation. Measurements were included from the superotemporal vessel pair. A paired t-test was used for statistical analysis.Fifty-nine infants, (58% female, were included with mean gestational age of 40 ± 1.3 weeks (mean ± SD and mean post-natal age of 16 ± 4.8 days. A total of 28 images were selected for retinal oximetry analysis. The ODR was

  12. Retinal vascular calibres are significantly associated with cardiovascular risk factors

    DEFF Research Database (Denmark)

    von Hanno, T.; Bertelsen, G.; Sjølie, Anne K.

    2014-01-01

    . Association between retinal vessel calibre and the cardiovascular risk factors was assessed by multivariable linear and logistic regression analyses. Results: Retinal arteriolar calibre was independently associated with age, blood pressure, HbA1c and smoking in women and men, and with HDL cholesterol in men......Purpose: To describe the association between retinal vascular calibres and cardiovascular risk factors. Methods: Population-based cross-sectional study including 6353 participants of the TromsO Eye Study in Norway aged 38-87years. Retinal arteriolar calibre (central retinal artery equivalent...... cardiovascular risk factors were independently associated with retinal vascular calibre, with stronger effect of HDL cholesterol and BMI in men than in women. Blood pressure and smoking contributed most to the explained variance....

  13. Zingiber officinale attenuates retinal microvascular changes in diabetic rats via anti-inflammatory and antiangiogenic mechanisms

    Science.gov (United States)

    Dongare, Shirish; Mathur, Rajani; Saxena, Rohit; Mathur, Sandeep; Agarwal, Renu; Nag, Tapas C.; Srivastava, Sushma; Kumar, Pankaj

    2016-01-01

    Purpose Diabetic retinopathy is a common microvascular complication of long-standing diabetes. Several complex interconnecting biochemical pathways are activated in response to hyperglycemia. These pathways culminate into proinflammatory and angiogenic effects that bring about structural and functional damage to the retinal vasculature. Since Zingiber officinale (ginger) is known for its anti-inflammatory and antiangiogenic properties, we investigated the effects of its extract standardized to 5% 6-gingerol, the major active constituent of ginger, in attenuating retinal microvascular changes in rats with streptozotocin-induced diabetes. Methods Diabetic rats were treated orally with the vehicle or the ginger extract (75 mg/kg/day) over a period of 24 weeks along with regular monitoring of bodyweight and blood glucose and weekly fundus photography. At the end of the 24-week treatment, the retinas were isolated for histopathological examination under a light microscope, transmission electron microscopy, and determination of the retinal tumor necrosis factor-α (TNF-α), nuclear factor-kappa B (NF-κB), and vascular endothelial growth factor (VEGF) levels. Results Oral administration of the ginger extract resulted in significant reduction of hyperglycemia, the diameter of the retinal vessels, and vascular basement membrane thickness. Improvement in the architecture of the retinal vasculature was associated with significantly reduced expression of NF-κB and reduced activity of TNF-α and VEGF in the retinal tissue in the ginger extract–treated group compared to the vehicle-treated group. Conclusions The current study showed that ginger extract containing 5% of 6-gingerol attenuates the retinal microvascular changes in rats with streptozotocin-induced diabetes through anti-inflammatory and antiangiogenic actions. Although precise molecular targets remain to be determined, 6-gingerol seems to be a potential candidate for further investigation. PMID:27293376

  14. Racial differences in retinal vessel geometric characteristics: a multiethnic study in healthy Asians.

    Science.gov (United States)

    Li, Xiang; Wong, Wan Ling; Cheung, Carol Yim-Lui; Cheng, Ching-Yu; Ikram, Mohammad Kamran; Li, Jialiang; Chia, Kee Seng; Wong, Tien Yin

    2013-05-01

    To investigate potential racial/ethnic differences in retinal vascular geometric parameters in a multiethnic Asian population (Chinese, Malay, and Indian) free of clinical diseases. A series of retinal vascular parameters were measured from retinal photographs using a computer-assisted program following a standardized protocol. Healthy participants were defined as nonsmokers, the absence of diabetes mellitus, uncontrolled hypertension, obesity, stroke, heart disease, glaucoma, and retinopathy. THERE WERE SIGNIFICANT DIFFERENCES IN MEASUREMENTS OF RETINAL VASCULAR CALIBER, TORTUOSITY, AND FRACTAL DIMENSION AMONG THE THREE ETHNIC GROUPS. IN MULTIPLE LINEAR REGRESSION MODEL CONTROLLING FOR AGE, SEX, BODY MASS INDEX, SYSTOLIC BLOOD PRESSURE, CHOLESTEROL, AND GLUCOSE LEVELS, INDIANS HAD THE LARGEST ARTERIOLAR AND VENULAR CALIBERS (ARTERIOLES [SE]: 158.94 μm [1.00]; venules: 228.26 μm [1.53]), followed by Malays (arterioles: 138.31 μm [0.74]; venules: 204.26 μm [1.13]), and then Chinese (arterioles: 131.20 μm [0.84]; venules: 195.09 μm [1.28]). Chinese had the largest arteriolar and venular tortuosity (arterioles [× $${10}^{5}$$]: 7.20 [0.08] VENULES [ $${10}^{5}$$]: 9.09 [0.10]), and venular fractal dimension (1.244 [0.003]). There were no statistically significant differences in other retinal vascular parameters after correcting multiple comparisons by the method of modified false discovery rate. We found that among ethnic groups composed of healthy Chinese, Malay, and Indians, there were statistically significant differences in several retinal parameters. There exist racial influences in retinal vascular parameters and other yet unknown or unmeasured environmental factor or lifestyle habits and genetic variations not related to race that may also contribute to these differences.

  15. FFTF and CRBRP reactor vessels

    International Nuclear Information System (INIS)

    Morgan, R.E.

    1977-01-01

    The Fast Flux Test Facility (FFTF) reactor vessel and the Clinch River Breeder Reactor Plant (CRBRP) reactor vessel each serve to enclose a fast spectrum reactor core, contain the sodium coolant, and provide support and positioning for the closure head and internal structure. Each vessel is located in its reactor cavity and is protected by a guard vessel which would ensure continued decay heat removal capability should a major system leak develop. Although the two plants have significantly different thermal power ratings, 400 megawatts for FFTF and 975 megawatts for CRBRP, the two reactor vessels are comparable in size, the CRBRP vessel being approximately 28% longer than the FFTF vessel. The FFTF vessel diameter was controlled by the space required for the three individual In-Vessel Handling Machines and Instrument Trees. Utilization of the triple rotating plug scheme for CRBRP refueling enables packaging of the larger CRBRP core in a vessel the same diameter as the FFTF vessel

  16. Non-invasive imaging of retinal blood flow in myeloproliferative neoplasms

    DEFF Research Database (Denmark)

    Willerslev, Anne; Hansen, Mathias M; Klefter, Oliver Niels

    2017-01-01

    PURPOSE: To study the circulation in the retinal vessels in patients with blood dyscrasia due to myeloproliferative neoplasms using non-invasive retinal imaging. METHODS: Prospective consecutive case series of seven treatment-naïve patients with chronic myeloid leukaemia (n = 2), polycythemia vera...... present at baseline in patients with chronic myeloid leukaemia and were replaced by normal patterns at follow-up. Retinopathy, in the form of cotton-wool spots and retinal haemorrhages, was found at presentation in the two patients with chronic myeloid leukaemia and in one patient with polycythemia vera...

  17. An Unusual Case of Extensive Lattice Degeneration and Retinal Detachment.

    Science.gov (United States)

    Mathew, David J; Sarma, Saurabh Kumar; Basaiawmoit, Jennifer V

    2016-07-01

    Lattice degeneration of the retina is not infrequently encountered on a dilated retinal examination and many of them do not need any intervention. We report a case of atypical lattice degeneration variant with peripheral retinal detachment. An asymptomatic 35-year-old lady with minimal refractive error was found to have extensive lattice degeneration, peripheral retinal detachment and fibrotic changes peripherally with elevation of retinal vessels on dilated retinal examination. There were also areas of white without pressure, chorioretinal scarring and retinal breaks. All the changes were limited to beyond the equator but were found to span 360 degrees. She was treated with barrage laser all around to prevent extension of the retinal detachment posteriorly. She remained stable till her latest follow-up two years after the barrage laser. This case is reported for its rarity with a discussion of the probable differential diagnoses. To the best of our knowledge, this is the first report of such findings in lattice degeneration.

  18. Comparative analysis of the development of collateral vessels in macular edema due to branch retinal vein occlusion following grid laser or ranibizumab treatment

    Directory of Open Access Journals (Sweden)

    Kokolaki AE

    2015-09-01

    Full Text Available Afroditi Eleni Kokolaki, Ilias Georgalas, Chryssanthi Koutsandrea, Athanasios Kotsolis, Maria Niskopoulou, Ioannis LadasDepartment of Ophthalmology, University of Athens, Athens, Greece Purpose: To evaluate the differences in the development of collateral vessels in patients with macular edema due to branch retinal vein occlusion (BRVO after treatment with either grid laser or ranibizumab (RNB.Methods: Comparative study including patients with macular edema due to acute BRVO and best-corrected visual acuity (BCVA between 20/40 and 20/200. The sample was divided into two groups according to the treatment applied: laser group, including eyes treated with Argon laser when retinal hemorrhages were sufficiently absorbed to perform the treatment, and RNB group,  including patients treated initially with one monthly intravitreal injection for a period of 3 months of RNB and more injections according to need thereafter.. Before treatment patients in both groups, received a complete ophthalmic examination, including BCVA, fundus examination, optical coherence tomography, fundus color photography, and fundus fluorescein angiography (FA. This same protocol of examination was repeated in every visit after treatment, except FA that was only repeated every 3 months. The detection of the collateral vessels was done by two experienced examiners based on the analysis of the early phase of the FA. If there was a discrepancy in their judgment, the criterion of a third examiner evaluating the FA was considered.Results: Mean baseline BCVA was 0.86±0.26 and 0.82±0.25 (logMAR [logarithm of the minimum angle of resolution] in the RNB and laser groups, respectively (P=0.83. At the end of the follow-up, mean BCVA was 0.38±0.18 and 0.64±0.33 (logMAR in the RNB and laser groups, respectively. The difference in the final BCVA between both groups was statistically significant (P=0.002. Collaterals developed in both groups; 66.67% of patients (14 out of 21

  19. Intraocular pressure, blood pressure, and retinal blood flow autoregulation: a mathematical model to clarify their relationship and clinical relevance.

    Science.gov (United States)

    Guidoboni, Giovanna; Harris, Alon; Cassani, Simone; Arciero, Julia; Siesky, Brent; Amireskandari, Annahita; Tobe, Leslie; Egan, Patrick; Januleviciene, Ingrida; Park, Joshua

    2014-05-29

    This study investigates the relationship between intraocular pressure (IOP) and retinal hemodynamics and predicts how arterial blood pressure (BP) and blood flow autoregulation (AR) influence this relationship. A mathematical model is developed to simulate blood flow in the central retinal vessels and retinal microvasculature as current flowing through a network of resistances and capacitances. Variable resistances describe active and passive diameter changes due to AR and IOP. The model is validated by using clinically measured values of retinal blood flow and velocity. The model simulations for six theoretical patients with high, normal, and low BP (HBP-, NBP-, LBP-) and functional or absent AR (-wAR, -woAR) are compared with clinical data. The model predicts that NBPwAR and HBPwAR patients can regulate retinal blood flow (RBF) as IOP varies between 15 and 23 mm Hg and between 23 and 29 mm Hg, respectively, whereas LBPwAR patients do not adequately regulate blood flow if IOP is 15 mm Hg or higher. Hemodynamic alterations would be noticeable only if IOP changes occur outside of the regulating range, which, most importantly, depend on BP. The model predictions are consistent with clinical data for IOP reduction via surgery and medications and for cases of induced IOP elevation. The theoretical model results suggest that the ability of IOP to induce noticeable changes in retinal hemodynamics depends on the levels of BP and AR of the individual. These predictions might help to explain the inconsistencies found in the clinical literature concerning the relationship between IOP and retinal hemodynamics. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

  20. Automated detection of retinal whitening in malarial retinopathy

    Science.gov (United States)

    Joshi, V.; Agurto, C.; Barriga, S.; Nemeth, S.; Soliz, P.; MacCormick, I.; Taylor, T.; Lewallen, S.; Harding, S.

    2016-03-01

    Cerebral malaria (CM) is a severe neurological complication associated with malarial infection. Malaria affects approximately 200 million people worldwide, and claims 600,000 lives annually, 75% of whom are African children under five years of age. Because most of these mortalities are caused by the high incidence of CM misdiagnosis, there is a need for an accurate diagnostic to confirm the presence of CM. The retinal lesions associated with malarial retinopathy (MR) such as retinal whitening, vessel discoloration, and hemorrhages, are highly specific to CM, and their detection can improve the accuracy of CM diagnosis. This paper will focus on development of an automated method for the detection of retinal whitening which is a unique sign of MR that manifests due to retinal ischemia resulting from CM. We propose to detect the whitening region in retinal color images based on multiple color and textural features. First, we preprocess the image using color and textural features of the CMYK and CIE-XYZ color spaces to minimize camera reflex. Next, we utilize color features of the HSL, CMYK, and CIE-XYZ channels, along with the structural features of difference of Gaussians. A watershed segmentation algorithm is used to assign each image region a probability of being inside the whitening, based on extracted features. The algorithm was applied to a dataset of 54 images (40 with whitening and 14 controls) that resulted in an image-based (binary) classification with an AUC of 0.80. This provides 88% sensitivity at a specificity of 65%. For a clinical application that requires a high specificity setting, the algorithm can be tuned to a specificity of 89% at a sensitivity of 82%. This is the first published method for retinal whitening detection and combining it with the detection methods for vessel discoloration and hemorrhages can further improve the detection accuracy for malarial retinopathy.

  1. Optical Coherence Tomography Angiography of Retinal Cavernous Hemangioma.

    Science.gov (United States)

    Pierro, Luisa; Marchese, Alessandro; Gagliardi, Marco; Bandello, Francesco

    2017-08-01

    Retinal cavernous hemangioma is a rare, benign, retinal tumor characterized by angiomatous proliferation of vessels within the inner retina or the optic disc.1 Here we report a case of retinal cavernous hemangioma on the margin of the optic disc in the right eye of a 61-year-old asymptomatic female. The lesion was studied with multimodal imaging which included structural optical coherence tomography, fluorescein angiography, blue fundus auto-fluorescence, optical coherence tomography angiography (OCTA) (DRI OCT Triton; Topcon, Tokyo, Japan) and visual field examination. Blood circulation inside retinal cavernous hemangioma lesion is typically low-stagnant.2 However, OCTA demonstrated blood flow inside the lesion, illustrating its vascular circulation.3 Visual field was within the normal limits, except from a slight enlargement of the blind spot. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:684-685.]. Copyright 2017, SLACK Incorporated.

  2. Zerumbone, a Bioactive Sesquiterpene, Ameliorates Diabetes-Induced Retinal Microvascular Damage through Inhibition of Phospho-p38 Mitogen-Activated Protein Kinase and Nuclear Factor-κB Pathways

    Directory of Open Access Journals (Sweden)

    Wayne Young Liu

    2016-12-01

    Full Text Available Zerumbone ameliorates retinal damage by blocking advanced glycation end products and their receptor system in streptozotocin-diabetic rats. Because of the multiple factors involved in diabetic retinopathy (DR etiology, the mechanisms of zerumbone that are mainly responsible for its ameliorative effect on DR need to be further clarified. In the present study, zerumbone (20 mg or 40 mg/kg or fenofibric acid (100 mg/kg was orally administered to diabetic rats by intragastric gavage once daily for three consecutive months. Zerumbone displayed similar characteristics to fenofibric acid in reducing retinal vascular permeability and leukostasis in diabetic rats. Fundus photographs showed that large retinal vessel diameters were decreased in zerumbone-treated diabetic rats. Zerumbone not only down-regulated the gene expression of retinal angiogenic parameters, but also reduced the expression of inflammatory cytokines and chemokines in the retina of diabetic rats. Moreover, zerumbone reduced the p38 MAPK phosphorylation and abrogated the nuclear translocation of NF-κB p65 in the retina of diabetic rats. In conclusion, treatment of diabetic rats with zerumbone attenuates the severity of retinal inflammation and angiogenesis, via inhibition of p38 MAPK and NF-κB signaling pathways. These benefits of zerumbone for DR appear to be linked to its antihyperglycemic and antihyperlipidemic effects.

  3. Nampt/PBEF/visfatin serum levels: a new biomarker for retinal blood vessel occlusions

    Directory of Open Access Journals (Sweden)

    Kaja S

    2015-04-01

    Full Text Available Simon Kaja,1,* Anna A Shah,1,* Shamim A Haji,1,* Krishna B Patel,1 Yuliya Naumchuk,1 Alexander Zabaneh,1 Bryan C Gerdes,1 Nancy Kunjukunju,1 Nelson R Sabates,1 Michael A Cassell,1 Ron K Lord,1 Kevin P Pikey,1 Abraham Poulose,1 Peter Koulen1,21Vision Research Center, Department of Ophthalmology, 2Department of Basic Medical Science, School of Medicine, University of Missouri – Kansas City, Kansas City, MO, USA*These authors contributed equally to this workAbstract: The main objective of the study was to quantify serum levels of nicotinamide phosphoribosyltransferase (Nampt/pre-B-Cell colony-enhancing factor 1/visfatin in subjects with a history of retinal vascular occlusions (RVOs, disease conditions characterized by pronounced ischemia, and metabolic energy deficits. A case–control study of 18 subjects with a history of RVO as well as six healthy volunteers is presented. Serum Nampt levels were quantified using a commercially available enzyme-linked immunosorbent assay kit. Serum Nampt levels were 79% lower in patients with a history of RVO compared with that in healthy volunteers (P<0.05. There was no statistically significant difference among the types of RVOs, specifically branch retinal vein occlusions (n=7, central retinal vein occlusions (n=5, hemiretinal vein occlusions (n=3, and central retinal artery occlusions (n=3; P=0.69. Further studies are needed to establish the temporal kinetics of Nampt expression and to determine whether Nampt may represent a novel biomarker to identify at-risk populations, or whether it is a druggable target with the potential to ameliorate the long-term complications associated with the condition, ie, macular edema, macular ischemia, neovascularization, and permanent loss of vision.Keywords: Nampt, PBEF, visfatin, nicotinamide phosphoribosyltransferase, pre-B-cell colony-enhancing factor, retinal artery occlusion, retinal vein occlusion, biomarker, retina, vasculature

  4. Bilateral retinal vein occlusion and rubeosis irides: lessons to learn.

    Science.gov (United States)

    Md Noh, Umi Kalthum; Ahem, Amin; Mustapha, Mushawiahti

    2013-01-01

    Uncontrolled hypertension is well- known to give rise to systemic complications involving multiple central organs. Artherosclerosis leads to damage of the retinal vessels wall, contributing to venous stasis, thrombosis and finally, occlusion. Retinal vein occlusions compromise vision through development of ischaemic maculopathy, macular oedema, and rubeotic glaucoma. Laser photocoagulation remains the definitive treatment for ischaemic vein occlusion with secondary neovascularization. Timely treatment with anti- vascular endothelial growth factor prevents development of rubeotic glaucoma. We hereby report an unusual case of bilateral retinal vein occlusion complicated by rubeosis irides, which was successfully managed to improve vision and prevent rubeotic glaucoma.

  5. Hypertensive retinopathy identification through retinal fundus image using backpropagation neural network

    Science.gov (United States)

    Syahputra, M. F.; Amalia, C.; Rahmat, R. F.; Abdullah, D.; Napitupulu, D.; Setiawan, M. I.; Albra, W.; Nurdin; Andayani, U.

    2018-03-01

    Hypertension or high blood pressure can cause damage of blood vessels in the retina of eye called hypertensive retinopathy (HR). In the event Hypertension, it will cause swelling blood vessels and a decrese in retina performance. To detect HR in patients body, it is usually performed through physical examination of opthalmoscope which is still conducted manually by an ophthalmologist. Certainly, in such a manual manner, takes a ong time for a doctor to detetct HR on aa patient based on retina fundus iamge. To overcome ths problem, a method is needed to identify the image of retinal fundus automatically. In this research, backpropagation neural network was used as a method for retinal fundus identification. The steps performed prior to identification were pre-processing (green channel, contrast limited adapative histogram qualization (CLAHE), morphological close, background exclusion, thresholding and connected component analysis), feature extraction using zoning. The results show that the proposed method is able to identify retinal fundus with an accuracy of 95% with maximum epoch of 1500.

  6. Retinitis pigmentosa, pigmentary retinopathies, and neurologic diseases.

    Science.gov (United States)

    Bhatti, M Tariq

    2006-09-01

    Retinitis pigmentosa (RP) refers to a group of inherited retinal diseases with phenotypic and genetic heterogeneity. The pathophysiologic basis of the progressive visual loss in patients with RP is not completely understood but is felt to be due to a primary retinal photoreceptor cell degenerative process mainly affecting the rods of the peripheral retina. In most cases RP is seen in isolation (nonsyndromic), but in some other cases it may be a part of a genetic, metabolic, or neurologic syndrome or disorder. Nyctalopia, or night blindness, is the most common symptom of RP. The classic fundus appearance of RP includes retinal pigment epithelial cell changes resulting in retinal hypo- or hyperpigmentation ("salt-and-pepper"), retinal granularity, and bone spicule formation. The retinal vessels are often narrowed or attenuated and there is a waxy pallor appearance of the optic nerve head. Electroretinography will demonstrate rod and cone photoreceptor cell dysfunction and is a helpful test in the diagnosis and monitoring of patients with RP. A detailed history with pedigree analysis, a complete ocular examination, and the appropriate paraclinical testing should be performed in patients complaining of visual difficulties at night or in dim light. This review discusses the clinical manifestations of RP as well as describing the various systemic diseases, with a special emphasis on neurologic diseases, associated with a pigmentary retinopathy.

  7. Oxygen-induced retinopathy in mice with retinal photoreceptor cell degeneration.

    Science.gov (United States)

    Zhang, Qian; Zhang, Zuo-Ming

    2014-04-25

    It is reported that retinal neovascularization seems to rarely co-exist with retinitis pigmentosa in patients and in some mouse models; however, it is not widely acknowledged as a universal phenomenon in all strains of all animal species. We aimed to further explore this phenomenon with an oxygen-induced retinopathy model in mice with retinal photoreceptor cell degeneration. Oxygen-induced retinopathy of colored and albino mice with rapid retinal degeneration were compared to homologous wild-type mice. The retinas were analyzed using high-molecular-weight FITC-dextran stained flat-mount preparation, hematoxylin and eosin (H&E) stained cross-sections, an immunohistochemical test for vascular endothelial growth factor (VEGF) distribution and Western blotting for VEGF expression after exposure to hyperoxia between postnatal days 17 (P17) and 21. Leakage and areas of non-perfusion of the retinal blood vessels were alleviated in the retinal degeneration mice. The number of preretinal vascular endothelial cell nuclei in the retinal degeneration mice was smaller than that in the homologous wild-type mice after exposure to hyperoxia (Poxygen-induced retinopathy was positively correlated with the VEGF expression level. However, the VEGF expression level was lower in the retinal degeneration mice. Proliferative retinopathy occurred in mice with rapid retinal degeneration, but retinal photoreceptor cell degeneration could partially restrain the retinal neovascularization in this rapid retinal degeneration mouse model. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. Intravascular drug delivery with a pulsed liquid microjet.

    Science.gov (United States)

    Fletcher, Daniel A; Palanker, Daniel V; Huie, Philip; Miller, Jason; Marmor, Michael F; Blumenkranz, Mark S

    2002-09-01

    Occlusions of the retinal veins and arteries, associated with diseases such as hypertension and arteriosclerosis, are a major cause of severe and irreversible loss of vision. Treatments for retinal vascular diseases have been unsatisfactory owing in part to the difficulty of delivering drugs to the site of disease within the eye. In this article, we demonstrate that a new device, the vapor bubble-driven pulsed liquid microjet, can deliver drugs into the lumen of small vessels such as those found in the retina. A 15- micro m-diameter liquid jet traveling at more than 60 m/s was shown to penetrate and deliver fluid through the wall of a blood vessel that was 60 micro m in diameter. Perforation of the wall of the blood vessel did not extend beyond the jet diameter.

  9. Optical Coherence Tomography Angiography Vessel Density in Healthy, Glaucoma Suspect, and Glaucoma Eyes

    Science.gov (United States)

    Yarmohammadi, Adeleh; Zangwill, Linda M.; Diniz-Filho, Alberto; Suh, Min Hee; Manalastas, Patricia Isabel; Fatehee, Naeem; Yousefi, Siamak; Belghith, Akram; Saunders, Luke J.; Medeiros, Felipe A.; Huang, David; Weinreb, Robert N.

    2016-01-01

    Purpose The purpose of this study was to compare retinal nerve fiber layer (RNFL) thickness and optical coherence tomography angiography (OCT-A) retinal vasculature measurements in healthy, glaucoma suspect, and glaucoma patients. Methods Two hundred sixty-one eyes of 164 healthy, glaucoma suspect, and open-angle glaucoma (OAG) participants from the Diagnostic Innovations in Glaucoma Study with good quality OCT-A images were included. Retinal vasculature information was summarized as a vessel density map and as vessel density (%), which is the proportion of flowing vessel area over the total area evaluated. Two vessel density measurements extracted from the RNFL were analyzed: (1) circumpapillary vessel density (cpVD) measured in a 750-μm-wide elliptical annulus around the disc and (2) whole image vessel density (wiVD) measured over the entire image. Areas under the receiver operating characteristic curves (AUROC) were used to evaluate diagnostic accuracy. Results Age-adjusted mean vessel density was significantly lower in OAG eyes compared with glaucoma suspects and healthy eyes. (cpVD: 55.1 ± 7%, 60.3 ± 5%, and 64.2 ± 3%, respectively; P glaucoma and healthy eyes, the age-adjusted AUROC was highest for wiVD (0.94), followed by RNFL thickness (0.92) and cpVD (0.83). The AUROCs for differentiating between healthy and glaucoma suspect eyes were highest for wiVD (0.70), followed by cpVD (0.65) and RNFL thickness (0.65). Conclusions Optical coherence tomography angiography vessel density had similar diagnostic accuracy to RNFL thickness measurements for differentiating between healthy and glaucoma eyes. These results suggest that OCT-A measurements reflect damage to tissues relevant to the pathophysiology of OAG. PMID:27409505

  10. Retinal vascular imaging technology to monitor disease severity and complications in type 1 diabetes mellitus: A systematic review.

    Science.gov (United States)

    Kee, Ae Ra; Wong, Tien Yin; Li, Ling-Jun

    2017-02-01

    Type 1 diabetes mellitus (T1DM) is a major disease affecting a large number of young patients. In the recent years, retinal vascular imaging has provided an objective assessment of vascular health in patients with T1DM. Our study aimed to review the current literature on retinal vascular parameters in young patients with T1DM in order to understand the following: (i) How retinal vessels are affected in T1DM (ii) How such vascular changes can be predictive of future diabetic microvascular complications METHODS: We performed a systematic review and extracted relevant data from 17 articles. We found significant correlations between retinal vessel changes and diabetes-related risk factors (eg, hypertension, hyperlipidemia, and obesity), diabetes-related features (eg, diabetes duration and glycemic control), and diabetes-related microvascular complications (eg, diabetic retinopathy, nephropathy, and neuropathy). Our findings suggest that retinal microvasculature is associated with both disease severity and complications in young patients with T1DM. © 2016 John Wiley & Sons Ltd.

  11. Role of the Norrie disease pseudoglioma gene in sprouting angiogenesis during development of the retinal vasculature.

    Science.gov (United States)

    Luhmann, Ulrich F O; Lin, Jihong; Acar, Niyazi; Lammel, Stefanie; Feil, Silke; Grimm, Christian; Seeliger, Mathias W; Hammes, Hans-Peter; Berger, Wolfgang

    2005-09-01

    To characterize developmental defects and the time course of Norrie disease in retinal and hyaloid vasculature during retinal development and to identify underlying molecular angiogenic pathways that may be affected in Norrie disease, exudative vitreoretinopathy, retinopathy of prematurity, and Coats' disease. Norrie disease pseudoglioma homologue (Ndph)-knockout mice were studied during retinal development at early postnatal (p) stages (p5, p10, p15, and p21). Histologic techniques, quantitative RT-PCR, ELISA, and Western blot analyses provided molecular data, and scanning laser ophthalmoscopy (SLO) angiography and electroretinography (ERG) were used to obtain in vivo data. The data showed that regression of the hyaloid vasculature of Ndph-knockout mice occurred but was drastically delayed. The development of the superficial retinal vasculature was strongly delayed, whereas the deep retinal vasculature did not form because of the blockage of vessel outgrowth into the deep retinal layers. Subsequently, microaneurysm-like lesions formed. Several angiogenic factors were differentially transcribed during retinal development. Increased levels of hypoxia inducible factor-1alpha (HIF1alpha) and VEGFA, as well as a characteristic ERG pattern, confirmed hypoxic conditions in the inner retina of the Ndph-knockout mouse. These data provide evidence for a crucial role of Norrin in hyaloid vessel regression and in sprouting angiogenesis during retinal vascular development, especially in the development of the deep retinal capillary networks. They also suggest an early and a late phase of Norrie disease and may provide an explanation for similar phenotypic features of allelic retinal diseases in mice and patients as secondary consequences of pathologic hypoxia.

  12. A Fovea Localization Scheme Using Vessel Origin-Based Parabolic Model

    Directory of Open Access Journals (Sweden)

    Chun-Yuan Yu

    2014-09-01

    Full Text Available At the center of the macula, fovea plays an important role in computer-aided diagnosis. To locate the fovea, this paper proposes a vessel origin (VO-based parabolic model, which takes the VO as the vertex of the parabola-like vasculature. Image processing steps are applied to accurately locate the fovea on retinal images. Firstly, morphological gradient and the circular Hough transform are used to find the optic disc. The structure of the vessel is then segmented with the line detector. Based on the characteristics of the VO, four features of VO are extracted, following the Bayesian classification procedure. Once the VO is identified, the VO-based parabolic model will locate the fovea. To find the fittest parabola and the symmetry axis of the retinal vessel, an Shift and Rotation (SR-Hough transform that combines the Hough transform with the shift and rotation of coordinates is presented. Two public databases of retinal images, DRIVE and STARE, are used to evaluate the proposed method. The experiment results show that the average Euclidean distances between the located fovea and the fovea marked by experts in two databases are 9.8 pixels and 30.7 pixels, respectively. The results are stronger than other methods and thus provide a better macular detection for further disease discovery.

  13. Laser beam diameter for port wine stain treatment

    NARCIS (Netherlands)

    Keijzer, M.; Pickering, J. W.; van Gemert, M. J.

    1991-01-01

    Optimal port wine stain treatment requires the selective absorption of light by the ectatic blood vessels. We investigated whether deeper blood vessels can be coagulated, without damaging other cutaneous structures, by varying the laser beam diameter. The penetration of the light was simulated with

  14. Comparison of subjective and objective methods to determine the retinal arterio-venous ratio using fundus photography

    Directory of Open Access Journals (Sweden)

    Rebekka Heitmar

    2015-10-01

    Conclusion: Grader education and experience leads to inter-grader differences but more importantly, subjective grading is not capable to pick up subtle differences across healthy individuals and does not represent true AVR when compared with an objective assessment method. Technology advancements mean we no longer rely on opthalmoscopic evaluation but can capture and store fundus images with retinal cameras, enabling us to measure vessel calibre more accurately compared to visual estimation; hence it should be integrated in optometric practise for improved accuracy and reliability of clinical assessments of retinal vessel calibres.

  15. Towards Vision-Based Control of a Handheld Micromanipulator for Retinal Cannulation in an Eyeball Phantom

    Science.gov (United States)

    Becker, Brian C.; Yang, Sungwook; MacLachlan, Robert A.; Riviere, Cameron N.

    2012-01-01

    Injecting clot-busting drugs such as t-PA into tiny vessels thinner than a human hair in the eye is a challenging procedure, especially since the vessels lie directly on top of the delicate and easily damaged retina. Various robotic aids have been proposed with the goal of increasing safety by removing tremor and increasing precision with motion scaling. We have developed a fully handheld micromanipulator, Micron, that has demonstrated reduced tremor when cannulating porcine retinal veins in an “open sky” scenario. In this paper, we present work towards handheld robotic cannulation with the goal of vision-based virtual fixtures guiding the tip of the cannula to the vessel. Using a realistic eyeball phantom, we address sclerotomy constraints, eye movement, and non-planar retina. Preliminary results indicate a handheld micromanipulator aided by visual control is a promising solution to retinal vessel occlusion. PMID:24649479

  16. Body fat distribution, metabolic and inflammatory markers and retinal microvasculature in school-age children. The Generation R Study.

    Science.gov (United States)

    Gishti, O; Jaddoe, V W V; Hofman, A; Wong, T Y; Ikram, M K; Gaillard, R

    2015-10-01

    To examine the associations of body fatness, metabolic and inflammatory markers with retinal vessel calibers among children. We performed a population-based cohort study among 4145 school-age children. At the median age of 6.0 years (95% range 5.8, 8.0 years), we measured body mass index, total and abdominal fat mass, metabolic and inflammatory markers (blood levels of lipids, insulin and C-peptide and C-reactive protein) and retinal vascular calibers from retinal photographs. We observed that compared with normal weight children, obese children had narrower retinal arteriolar caliber (difference -0.21 s.d. score (SDS; 95% confidence interval (CI) -0.35, -0.06)), but not venular caliber. Continuous analyses showed that higher body mass index and total body fat mass, but not android/gynoid fat mass ratio and pre-peritoneal fat mass, were associated with narrower retinal arteriolar caliber (Pfat mass), but not with retinal venular caliber. Lipid and insulin levels were not associated with retinal vessel calibers. Higher C-reactive protein was associated with only wider retinal venular caliber (difference 0.10 SDS (95% CI 0.06, 0.14) per SDS increase in C-reactive protein). This latter association was not influenced by body mass index. Higher body fatness is associated with narrower retinal arteriolar caliber, whereas increased C-reactive protein levels are associated with wider retinal venular caliber. Increased fat mass and inflammation correlate with microvascular development from school-age onwards.

  17. Detection of retinal nerve fiber layer defects in retinal fundus images using Gabor filtering

    Science.gov (United States)

    Hayashi, Yoshinori; Nakagawa, Toshiaki; Hatanaka, Yuji; Aoyama, Akira; Kakogawa, Masakatsu; Hara, Takeshi; Fujita, Hiroshi; Yamamoto, Tetsuya

    2007-03-01

    Retinal nerve fiber layer defect (NFLD) is one of the most important findings for the diagnosis of glaucoma reported by ophthalmologists. However, such changes could be overlooked, especially in mass screenings, because ophthalmologists have limited time to search for a number of different changes for the diagnosis of various diseases such as diabetes, hypertension and glaucoma. Therefore, the use of a computer-aided detection (CAD) system can improve the results of diagnosis. In this work, a technique for the detection of NFLDs in retinal fundus images is proposed. In the preprocessing step, blood vessels are "erased" from the original retinal fundus image by using morphological filtering. The preprocessed image is then transformed into a rectangular array. NFLD regions are observed as vertical dark bands in the transformed image. Gabor filtering is then applied to enhance the vertical dark bands. False positives (FPs) are reduced by a rule-based method which uses the information of the location and the width of each candidate region. The detected regions are back-transformed into the original configuration. In this preliminary study, 71% of NFLD regions are detected with average number of FPs of 3.2 per image. In conclusion, we have developed a technique for the detection of NFLDs in retinal fundus images. Promising results have been obtained in this initial study.

  18. Retinal vascular injuries and intravitreal human embryonic stem cell-derived haemangioblasts.

    Science.gov (United States)

    Wang, Jin-Da; An, Ying; Zhang, Jing-Shang; Wan, Xiu-Hua; Zhang, Wei; Lanza, Robert; Lu, Shi-Jiang; Jonas, Jost B; Xu, Liang

    2017-09-01

    To investigate whether intravitreally applied haemangioblasts (HB) derived from human embryonic stem cells (hESCs) are helpful for the repair of vascular damage caused in animals by an oxygen-induced retinopathy (OIR), by an induced diabetic retinopathy (DR) or by an induced retinal ischaemia with subsequent reperfusion. Human embryonic stem cell-derived HBs were transplanted intravitreally into C57BL/6J mice (OIR model), into male Wistar rats with an induced DR and into male Wistar rats undergoing induced retinal ischaemia with subsequent reperfusion. Control groups of animals received an intravitreal injection of endothelial cells (ECs) or phosphate-buffered saline (PBS). We examined the vasculature integrity in the mice with OIR, the blood-retina barrier in the rats with induced DR, and retinal thickness and retinal ganglion cell density in retina flat mounts of the rats with the retinal ischaemic-reperfusion retinopathy. In the OIR model, the study group versus control groups showed a significantly (p < 0.001) smaller retinal avascular area [5.1 ± 2.7%;n = 18 animals versus 12.2 ± 2.8% (PBS group; n = 10 animals) and versus 11.8 ± 3.7% (EC group; n = 8 animals)] and less retinal neovascularization [6.3 ± 2.5%;n = 18 versus 15.2 ± 6.3% (n = 10; PBS group) and versus 15.8 ± 3.3% (n = 8; EC group)]. On retinal flat mounts, hESC-HBs were integrated into damaged retinal vessels and stained positive for PECAM (CD31) as EC marker. In the DR model, the study group versus the EC control group showed a significantly (p = 0.001) better blood-retina barrier function as measured at 2 days after the intravitreal injections [study group: 20.2 ± 12.8 μl/(g × hr); n = 6; versus EC control group: 52.9 ± 9.9 μl/(g × hr; n = 6)]. In the retinal ischaemia-reperfusion model, the groups did not differ significantly in retinal thickness and retinal ganglion cell density at 2, 5 and 7 days after baseline. By integrating into

  19. E2f1 mediates high glucose-induced neuronal death in cultured mouse retinal explants.

    Science.gov (United States)

    Wang, Yujiao; Zhou, Yi; Xiao, Lirong; Zheng, Shijie; Yan, Naihong; Chen, Danian

    2017-10-02

    Diabetic retinopathy (DR) is the most common complication of diabetes and remains one of the major causes of blindness in the world; infants born to diabetic mothers have higher risk of developing retinopathy of prematurity (ROP). While hyperglycemia is a major risk factor, the molecular and cellular mechanisms underlying DR and diabetic ROP are poorly understood. To explore the consequences of retinal cells under high glucose, we cultured wild type or E2f1 -/- mouse retinal explants from postnatal day 8 with normal glucose, high osmotic or high glucose media. Explants were also incubated with cobalt chloride (CoCl 2 ) to mimic the hypoxic condition. We showed that, at 7 days post exposure to high glucose, retinal explants displayed elevated cell death, ectopic cell division and intact retinal vascular plexus. Cell death mainly occurred in excitatory neurons, such as ganglion and bipolar cells, which were also ectopically dividing. Many Müller glial cells reentered the cell cycle; some had irregular morphology or migrated to other layers. High glucose inhibited the hyperoxia-induced blood vessel regression of retinal explants. Moreover, inactivation of E2f1 rescued high glucose-induced ectopic division and cell death of retinal neurons, but not ectopic cell division of Müller glial cells and vascular phenotypes. This suggests that high glucose has direct but distinct effects on retinal neurons, glial cells and blood vessels, and that E2f1 mediates its effects on retinal neurons. These findings shed new light onto mechanisms of DR and the fetal retinal abnormalities associated with maternal diabetes, and suggest possible new therapeutic strategies.

  20. The Protective Effects of Lycium Barbarum Polysaccharides on Transient Retinal Ischemia

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    Di Yang

    2011-05-01

    Full Text Available Retinal ischemia/reperfusion (I/R injury leads to irreversible neuronal death, glial activation, retinal swelling and oxidative stress. It is a common feature in various ocular diseases, such as glaucoma, diabetic retinopathy and amaurosis fugax. In the present study, we aimed to evaluate the effects of Lycium Barbarum Polysaccharides (LBP in a murine retinal I/R model. Mice were orally treated with either vehicle (PBS or LBP (1mg/kg daily for 1 week before induction of retinal ischemia. Retinae were collected after 2 hours ischemia and 22 hours reperfusion. Paraffin-embedded sections were prepared for immunohistochemical analyses. Significantly fewer viable cells were found in vehicle-treated retinae comparing to LBP group. This finding was further confirmed by TUNEL assay where significantly fewer apoptotic cells were identified in LBP-treated retinae. Additionally, retinal swelling induced by retinal I/R injury in the vehicle-treated group was not observed in LBP-treated group. Moreover, intense GFAP immunoreactivity and IgG extravasation were observed in vehicle-treated group but not in LBP treated group. The results showed that pre-treatment with LBP was protective in retinal I/R injury via reducing neuronal death, apoptosis, retinal swelling, GFAP activation and blood vessel leakage. LBP may be used as a preventive agent for retinal ischemia diseases.

  1. The Protective Effects of Lycium Barbarum Polysaccharides on Transient Retinal Ischemia

    Science.gov (United States)

    Yang, Di; Li, Suk-Yee; Yeung, Chung-Man; Yu, Wing-Yan; Chang, Raymond Chuen-Chung; So, Kwok-Fai; Wong, David; Lo, Amy C. Y.

    2011-01-01

    Retinal ischemia/reperfusion (I/R) injury leads to irreversible neuronal death, glial activation, retinal swelling and oxidative stress. It is a common feature in various ocular diseases, such as glaucoma, diabetic retinopathy and amaurosis fugax. In the present study, we aimed to evaluate the effects of Lycium Barbarum Polysaccharides (LBP) in a murine retinal I/R model. Mice were orally treated with either vehicle (PBS) or LBP (1mg/kg) daily for 1 week before induction of retinal ischemia. Retinae were collected after 2 hours ischemia and 22 hours reperfusion. Paraffin-embedded sections were prepared for immunohistochemical analyses. Significantly fewer viable cells were found in vehicle-treated retinae comparing to LBP group. This finding was further confirmed by TUNEL assay where significantly fewer apoptotic cells were identified in LBP-treated retinae. Additionally, retinal swelling induced by retinal I/R injury in the vehicle-treated group was not observed in LBP-treated group. Moreover, intense GFAP immunoreactivity and IgG extravasation were observed in vehicle-treated group but not in LBP treated group. The results showed that pre-treatment with LBP was protective in retinal I/R injury via reducing neuronal death, apoptosis, retinal swelling, GFAP activation and blood vessel leakage. LBP may be used as a preventive agent for retinal ischemia diseases.

  2. About a mechanism of the influence of shear stress for viscosity of the blood in vessels of small diameter

    Directory of Open Access Journals (Sweden)

    Лев Николаевич Катюхин

    2014-12-01

    Full Text Available It is proposed a physiological and experimentally confirmed explanation of Fåhraeus-Lindqvist-effect in capillaries using the profile analyses of osmotic deformability of red blood cells. It was shown the dose-dependent change of the erythrocytes deformability in the stage of isotropic spheres after forming artificial water pores (nystatin and occlusion (PbCl2 of available pores. The Sigma-effect reducing of hematocrit and viscosity in a shear flow of blood through the vessels of a small diameter was conditioned by the interchange of liquid phase between the erythrocyte and the plasma.

  3. Trypsin digest protocol to analyze the retinal vasculature of a mouse model.

    Science.gov (United States)

    Chou, Jonathan C; Rollins, Stuart D; Fawzi, Amani A

    2013-06-13

    Trypsin digest is the gold standard method to analyze the retinal vasculature (1-5). It allows visualization of the entire network of complex three-dimensional retinal blood vessels and capillaries by creating a two-dimensional flat-mount of the interconnected vascular channels after digestion of the non-vascular components of the retina. This allows one to study various pathologic vascular changes, such as microaneurysms, capillary degeneration, and abnormal endothelial to pericyte ratios. However, the method is technically challenging, especially in mice, which have become the most widely available animal model to study the retina because of the ease of genetic manipulations (6,7). In the mouse eye, it is particularly difficult to completely remove the non-vascular components while maintaining the overall architecture of the retinal blood vessels. To date, there is a dearth of literature that describes the trypsin digest technique in detail in the mouse. This manuscript provides a detailed step-by-step methodology of the trypsin digest in mouse retina, while also providing tips on troubleshooting difficult steps.

  4. Does bipolar electrocoagulation time affect vessel weld strength?

    Science.gov (United States)

    Harrison, J D; Morris, D L

    1991-01-01

    The value of the bipolar electrocoagulator in the haemostasis of bleeding ulcers is controversial. We have therefore investigated the effect of different coagulation times on vessel weld strength achieved by the bipolar device. Welds were then made in vessels of known diameter using a standard 10F endoscopic haemostatic probe at coagulation times of two and 20 seconds. The intravascular temperature achieved at each time was measured. Vessel weld strength achieved by bipolar electrocoagulation was much greater at 20 seconds (approximately twice that at two seconds) and was highly significantly greater at all vessel diameters. There was a gradual reduction in weld strength with increasing vessel diameter, an effect that was seen for both two and 20 seconds of electrocoagulation. Intravascular temperature was significantly higher at 20 seconds than at two seconds. We conclude that vessel weld strength is related to coagulation time and that any future studies comparing the bipolar electrocoagulator with other haemostatic devices should use longer periods of bipolar electrocoagulation and record the coagulation time in order to optimise the clinical value of the device. PMID:1864540

  5. Multimodal imaging of central retinal disease progression in a 2 year mean follow up of Retinitis Pigmentosa

    Science.gov (United States)

    Sujirakul, Tharikarn; Lin, Michael K.; Duong, Jimmy; Wei, Ying; Lopez-Pintado, Sara; Tsang, Stephen H.

    2015-01-01

    Purpose To determine the rate of progression and optimal follow up time in patients with advanced stage retinitis pigmentosa (RP) comparing the use of fundus autofluorescence imaging and spectral domain optical coherence tomography. Design Retrospective analysis of progression rate. Methods Longitudinal imaging follow up in 71 patients with retinitis pigmentosa was studied using the main outcome measurements of hyperautofluoresent ring horizontal diameter and vertical diameter along with ellipsoid zone line width from spectral domain optical coherence tomography. Test-retest reliability and the rate of progression were calculated. The interaction between the progression rates was tested for sex, age, mode of inheritance, and baseline measurement size. Symmetry of left and right eye progression rate was also tested. Results Significant progression was observed in >75% of patients during the 2 year mean follow up. The mean annual progression rates of ellipsoid zone line, and hyperautofluorescent ring horizontal diameter and vertical diameter were 0.45° (4.9%), 0.51° (4.1%), and 0.42° (4.0%), respectively. The e llipsoid zone line width, and hyperautofluorescent ring horizontal diameter and vertical diameter had low test-retest variabilities of 8.9%, 9.5% and 9.6%, respectively. This study is the first to demonstrate asymmetrical structural progression rate between right and left eye, which was found in 19% of patients. The rate of progression was significantly slower as the disease approached the fovea, supporting the theory that RP progresses in an exponential fashion. No significant interaction between progression rate and patient age, sex, or mode of inheritance was observed. Conclusions Fundus autofluorescence and optical coherence tomography detect progression in patients with RP reliably and with strong correlation. These parameters may be useful alongside functional assessments as the outcome measurements for future therapeutic trials. Follow-up at 1 year

  6. Type 3 Neovascularization Associated with Retinitis Pigmentosa.

    Science.gov (United States)

    Sayadi, Jihene; Miere, Alexandra; Souied, Eric H; Cohen, Salomon Y

    2017-01-01

    To report a case of type 3 neovascular lesion in a patient with retinitis pigmentosa (RP) complicated by macular edema. A 78-year-old man with a long follow-up for RP was referred for painless visual acuity decrease in the right eye. Best-corrected visual acuity was 20/125 in the right eye and 20/40 in the left. Fundus examination showed typical RP and macular edema in both eyes. In the right eye, spectral domain optical coherence tomography revealed a marked cystic macular edema associated with disruption of the Bruch membrane/retinal pigment epithelium complex overlying a pigmentary epithelium detachment, with a vascular structure which appeared to originate from the deep capillary plexus and to be connected with the subretinal pigment epithelium space. Optical coherence tomography angiography showed a high-flow vessel infiltrating the outer retinal layers in the deep capillary plexus segmentation, and a tuft-shaped, bright, high-flow network that seemed to be connected with the subretinal pigment epithelium space in the outer retinal layer segmentation. This presentation was consistent with an early type 3 neovascular lesion in the right eye. Type 3 neovascularization may be considered a possible complication of RP.

  7. Critical Endothelial Regulation by LRP5 during Retinal Vascular Development

    Science.gov (United States)

    Huang, Wei; Li, Qing; Amiry-Moghaddam, Mahmood; Hokama, Madoka; Sardi, Sylvia H.; Nagao, Masashi; Warman, Matthew L.; Olsen, Bjorn R.

    2016-01-01

    Vascular abnormalities in the eye are the leading cause of many forms of inherited and acquired human blindness. Loss-of-function mutations in the Wnt-binding co-receptor LRP5 leads to aberrant ocular vascularization and loss of vision in genetic disorders such as osteoporosis-pseudoglioma syndrome. The canonical Wnt-β-catenin pathway is known to regulate retinal vascular development. However, it is unclear what precise role LPR5 plays in this process. Here, we show that loss of LRP5 function in mice causes retinal hypovascularization during development as well as retinal neovascularization in adulthood with disorganized and leaky vessels. Using a highly specific Flk1-CreBreier line for vascular endothelial cells, together with several genetic models, we demonstrate that loss of endothelium-derived LRP5 recapitulates the retinal vascular defects in Lrp5-/- mice. In addition, restoring LRP5 function only in endothelial cells in Lrp5-/- mice rescues their retinal vascular abnormalities. Furthermore, we show that retinal vascularization is regulated by LRP5 in a dosage dependent manner and does not depend on LRP6. Our study provides the first direct evidence that endothelium-derived LRP5 is both necessary and sufficient to mediate its critical role in the development and maintenance of retinal vasculature. PMID:27031698

  8. Retinal vascular segmentation using superpixel-based line operator and its application to vascular topology estimation.

    Science.gov (United States)

    Na, Tong; Xie, Jianyang; Zhao, Yitian; Zhao, Yifan; Liu, Yue; Wang, Yongtian; Liu, Jiang

    2018-05-09

    Automatic methods of analyzing of retinal vascular networks, such as retinal blood vessel detection, vascular network topology estimation, and arteries/veins classification are of great assistance to the ophthalmologist in terms of diagnosis and treatment of a wide spectrum of diseases. We propose a new framework for precisely segmenting retinal vasculatures, constructing retinal vascular network topology, and separating the arteries and veins. A nonlocal total variation inspired Retinex model is employed to remove the image intensity inhomogeneities and relatively poor contrast. For better generalizability and segmentation performance, a superpixel-based line operator is proposed as to distinguish between lines and the edges, thus allowing more tolerance in the position of the respective contours. The concept of dominant sets clustering is adopted to estimate retinal vessel topology and classify the vessel network into arteries and veins. The proposed segmentation method yields competitive results on three public data sets (STARE, DRIVE, and IOSTAR), and it has superior performance when compared with unsupervised segmentation methods, with accuracy of 0.954, 0.957, and 0.964, respectively. The topology estimation approach has been applied to five public databases (DRIVE,STARE, INSPIRE, IOSTAR, and VICAVR) and achieved high accuracy of 0.830, 0.910, 0.915, 0.928, and 0.889, respectively. The accuracies of arteries/veins classification based on the estimated vascular topology on three public databases (INSPIRE, DRIVE and VICAVR) are 0.90.9, 0.910, and 0.907, respectively. The experimental results show that the proposed framework has effectively addressed crossover problem, a bottleneck issue in segmentation and vascular topology reconstruction. The vascular topology information significantly improves the accuracy on arteries/veins classification. © 2018 American Association of Physicists in Medicine.

  9. Macrovaso retiniano congênito: relato de caso Congenital retinal macrovessel: case report

    Directory of Open Access Journals (Sweden)

    Rodrigo Tavares Schueler

    2005-06-01

    Full Text Available O macrovaso retiniano congênito é rara anomalia vascular em que um vaso grande e suas tributárias cruzam a mácula. Descrevemos um caso de macrovaso retiniano em paciente com queixa de baixa acuidade visual.Congenital retinal macrovessel is a rare vascular anomaly in which a large vessel and its tributaries cross the macula. We describe a case of retinal macrovessel in a patient complaining of decrease in visual acuity.

  10. High-performance fiber/epoxy composite pressure vessels

    Science.gov (United States)

    Chiao, T. T.; Hamstad, M. A.; Jessop, E. S.; Toland, R. H.

    1978-01-01

    Activities described include: (1) determining the applicability of an ultrahigh-strength graphite fiber to composite pressure vessels; (2) defining the fatigue performance of thin-titanium-lined, high-strength graphite/epoxy pressure vessel; (3) selecting epoxy resin systems suitable for filament winding; (4) studying the fatigue life potential of Kevlar 49/epoxy pressure vessels; and (5) developing polymer liners for composite pressure vessels. Kevlar 49/epoxy and graphite fiber/epoxy pressure vessels, 10.2 cm in diameter, some with aluminum liners and some with alternation layers of rubber and polymer were fabricated. To determine liner performance, vessels were subjected to gas permeation tests, fatigue cycling, and burst tests, measuring composite performance, fatigue life, and leak rates. Both the metal and the rubber/polymer liner performed well. Proportionately larger pressure vessels (20.3 and 38 cm in diameter) were made and subjected to the same tests. In these larger vessels, line leakage problems with both liners developed the causes of the leaks were identified and some solutions to such liner problems are recommended.

  11. Targeting Therapy Resistant Tumor Vessels

    Science.gov (United States)

    2008-08-01

    Morris LS. Hysterectomy vs. resectoscopic endometrial ablation for the control of abnormal uterine bleeding . A cost-comparative study. J Reprod Med 1994;39...after the antibody treatment contain a pericyte coat, vessel architecture is normal, the diameter of the vessels is smaller (dilated, abnormal vessels...involvement of proteases from inflammatory mast cells and functionally abnormal (Carmeliet and Jain, 2000; Pasqualini (Coussens et al., 1999) and other bone

  12. Clinical reference value of retinal microvascular changes in patients with cerebral microbleeds

    Directory of Open Access Journals (Sweden)

    Ji-Yuan Guo

    2014-12-01

    Full Text Available AIM: To study clinical reference value of retinal microvascular changes in patients with cerebral microbleeds(CMBsand discuss its clinical significance. METHODS:From January 2012 to December 2013, 125 hospitalized patients were collected, including 81 cases were male, 44 cases were female, mean age 76.3±11.2 years old. For all patients, functions of liver and kidney, blood-lipoids, blood sugar and blood biochemical examination were tested, and fundus photography and cerebral MR was done. According to the fundus camera eyes, retinal arteriolar equivalent(RAE, retinal venular equivalent(RVE, retinal vein diameter ratio(AVRand arteriovenous crossing sign(AVNwere identified, CMBs were classified with cerebral MRI. All the data were processed by SPSS statistical software. RESULTS: The central retinal arteriolar equivalent(CRAE, central retinal venular equivalent(CRVEand AVR values in the eyes were found no statistical difference(PPCOCLUSION: The results show that retinal microvascular changes, especially small retinal vein arteriovenous cross width, and arteriovenous crossing phenomenon, in which CMBs will happen more likely. After sex, age, hypertension and hyperglycemia in patients with traditional cardiovascular risk factors being ruled out, the retinal microvascular changes are still relatively factors of CMB's occurrence.

  13. Accuracy of geometrical modelling of heat transfer from tissue to blood vessels

    NARCIS (Netherlands)

    Leeuwen, van G.M.J.; Kotte, A.N.T.J.; Bree, de J.; Koijk, van der J.F.; Crezee, J.; Lagendijk, J.J.W.

    1997-01-01

    We have developed a thermal model in which blood vessels are described as geometrical objects, 3D curves with associated diameters. Here the behaviour of the model is examined for low resolutions compared with the vessel diameter and for strongly curved vessels. The tests include a single straight

  14. Vessel size measurements in angiograms: A comparison of techniques

    International Nuclear Information System (INIS)

    Hoffmann, Kenneth R.; Nazareth, Daryl P.; Miskolczi, Laszlo; Gopal, Anant; Wang Zhou; Rudin, Stephen; Bednarek, Daniel R.

    2002-01-01

    As interventional procedures become more complicated, the need for accurate quantitative vascular information increases. In response to this need, many commercial vendors provide techniques for measurement of vessel sizes, usually based on derivative techniques. In this study, we investigate the accuracy of several techniques used in the measurement of vessel size. Simulated images of vessels having circular cross sections were generated and convolved with various focal spot distributions taking into account the magnification. These vessel images were then convolved with Gaussian image detector line spread functions (LSFs). Additionally, images of a phantom containing vessels with a range of diameters were acquired for the 4.5'', 6'', 9'', and 12'' modes of an image intensifier-TV (II-TV) system. Vessel sizes in the images were determined using a first-derivative technique, a second-derivative technique, a linear combination of these two measured sizes, a thresholding technique, a densitometric technique, and a model-based technique. For the same focal spot size, the shape of the focal spot distribution does not affect measured vessel sizes except at large magnifications. For vessels with diameters larger than the full-width-at-half-maximum (FWHM) of the LSF, accurate vessel sizes (errors ∼0.1 mm) could be obtained by using an average of sizes determined by the first and second derivatives. For vessels with diameters smaller than the FWHM of the LSF, the densitometric and model-based techniques can provide accurate vessel sizes when these techniques are properly calibrated

  15. Type 3 Neovascularization Associated with Retinitis Pigmentosa

    Directory of Open Access Journals (Sweden)

    Jihene Sayadi

    2017-04-01

    Full Text Available Purpose: To report a case of type 3 neovascular lesion in a patient with retinitis pigmentosa (RP complicated by macular edema. Case Report: A 78-year-old man with a long follow-up for RP was referred for painless visual acuity decrease in the right eye. Best-corrected visual acuity was 20/125 in the right eye and 20/40 in the left. Fundus examination showed typical RP and macular edema in both eyes. In the right eye, spectral domain optical coherence tomography revealed a marked cystic macular edema associated with disruption of the Bruch membrane/retinal pigment epithelium complex overlying a pigmentary epithelium detachment, with a vascular structure which appeared to originate from the deep capillary plexus and to be connected with the subretinal pigment epithelium space. Optical coherence tomography angiography showed a high-flow vessel infiltrating the outer retinal layers in the deep capillary plexus segmentation, and a tuft-shaped, bright, high-flow network that seemed to be connected with the subretinal pigment epithelium space in the outer retinal layer segmentation. This presentation was consistent with an early type 3 neovascular lesion in the right eye. Conclusion: Type 3 neovascularization may be considered a possible complication of RP.

  16. Evaluation of the Retinal Vasculature in Hypertension and Chronic Kidney Disease in an Elderly Population of Irish Nuns.

    Science.gov (United States)

    McGowan, Amy; Silvestri, Giuliana; Moore, Evelyn; Silvestri, Vittorio; Patterson, Christopher C; Maxwell, Alexander P; McKay, Gareth J

    2015-01-01

    Chronic kidney disease (CKD) and hypertension are global public health problems associated with considerable morbidity, premature mortality and attendant healthcare costs. Previous studies have highlighted that non-invasive examination of the retinal microcirculation can detect microvascular pathology that is associated with systemic disorders of the circulatory system such as hypertension. We examined the associations between retinal vessel caliber (RVC) and fractal dimension (DF), with both hypertension and CKD in elderly Irish nuns. Data from 1233 participants in the cross-sectional observational Irish Nun Eye Study (INES) were assessed from digital photographs with a standardized protocol using computer-assisted software. Multivariate regression analyses were used to assess associations with hypertension and CKD, with adjustment for age, body mass index (BMI), refraction, fellow eye RVC, smoking, alcohol consumption, ischemic heart disease (IHD), cerebrovascular accident (CVA), diabetes and medication use. In total, 1122 (91%) participants (mean age: 76.3 [range: 56-100] years) had gradable retinal images of sufficient quality for blood vessel assessment. Hypertension was significantly associated with a narrower central retinal arteriolar equivalent (CRAE) in a fully adjusted analysis (P = 0.002; effect size = -2.16 μm; 95% confidence intervals [CI]: -3.51, -0.81 μm). No significant associations between other retinal vascular parameters and hypertension or between any retinal vascular parameters and CKD were found. Individuals with hypertension have significantly narrower retinal arterioles which may afford an earlier opportunity for tailored prevention and treatment options to optimize the structure and function of the microvasculature, providing additional clinical utility. No significant associations between retinal vascular parameters and CKD were detected.

  17. Diabetes induces changes in neuroretina before retinal vessels: a spectral-domain optical coherence tomography study

    OpenAIRE

    Rodrigues, Eduardo B?chele; Urias, M?ller Gon?alves; Penha, Fernando Marcondes; Badar?, Emmerson; Novais, Eduardo; Meirelles, Rodrigo; Farah, Michel Eid

    2015-01-01

    Purpose To investigate retinal changes prior to vascular signs in patients with type 2 diabetes without diabetic retinopathy or with mild non proliferative diabetic retinopathy. Methods A cross-sectional study was performed in three groups: patients without diabetes, patients with type 2 diabetes without diabetic retinopathy, and patients with diabetes with mild diabetic retinopathy. Analysis of retinal layers was performed objectively with the Cirrus Review Software 6.0 (Carl Zeiss Meditec, ...

  18. Dealings between Cataract and Retinal Reattachment Surgery in PVR

    Directory of Open Access Journals (Sweden)

    Svenja Deuchler

    2016-01-01

    Full Text Available Introduction. To evaluate the impact of the eye lens status and oil side effects on the outcome of vitreoretinal surgery in retinal detachment with proliferative vitreoretinopathy (PVR and a temporary silicone oil tamponade (SOT. Methods. 101 eyes were analyzed retrospectively and 103 eyes prospectively in regard to their retinal reattachment success rate and key factors for the outcome. Subgroup analysis of 27 eyes with Scheimpflug lens photography (SLP before and after retinal reattachment service with SOT was performed. For SLP (65% phakic eyes a Pentacam densitometry reference body with 3 mm diameter was chosen and 3 segments (anterior/mid/posterior were evaluated separately after a quality check. Results. The retinal reattachment rate was highest in the prospective pseudophakic group (p=0.039. Lens transparency loss occurred earlier in middle aged patients than in younger patients. Besides the nucleus, layers posterior and anterior to it showed specific transparency changes. The emulsification rate was higher when eyes had been operated on in the anterior chamber before retinal reattachment service. Conclusions. Retinal reattachment surgery seems to benefit from preoperative cataract removal. We found significant lens changes in the nucleus as well as in the layers anterior and posterior to it. This corresponds to the histology of the lens epithelium published before.

  19. Retinal detachment and retinal holes in retinitis pigmentosa sine pigmento.

    Science.gov (United States)

    Csaky, K; Olk, R J; Mahl, C F; Bloom, S M

    1991-01-01

    Retinal detachment and retinal holes in two family members with retinitis pigmentosa sine pigmento are reported. We believe these are the first such cases reported in the literature. We describe the presenting symptoms and management, including cryotherapy, scleral buckling procedure, and sulfur hexafluoride injection (SF6), resulting in stable visual acuity in one case and retinal reattachment and improved visual acuity in the other case.

  20. Retinal vascular diameters in relation to physical activity in Danish children - The CHAMPS Eye Study

    DEFF Research Database (Denmark)

    Lundberg, Kristian; Tarp, Jakob; Vestergaard, Anders Højslet

    2018-01-01

    Our objective was to determine associations between retinal vascular caliber and physical activity (PA) in a school-based child cohort. In a prospective study we created a childhood cumulative average PA-index using objectively measured PA (accelerometry) assessed at four periods between 2009...

  1. Colour Doppler analysis of ophthalmic vessels in the diagnosis of carotic artery and retinal vein occlusion, diabetic retinopathy and glaucoma: systematic review of test accuracy studies.

    Science.gov (United States)

    Bittner, Mario; Faes, Livia; Boehni, Sophie C; Bachmann, Lucas M; Schlingemann, Reinier O; Schmid, Martin K

    2016-12-07

    Colour Doppler analysis of ophthalmic vessels has been proposed as a promising tool in the diagnosis of various eye diseases, but the available diagnostic evidence has not yet been assessed systematically. We performed a comprehensive systematic review of the literature on the diagnostic properties of Colour Doppler imaging (CDI) assessing ophthalmic vessels and provide an inventory of the available evidence. Eligible papers were searched electronically in (Pre) Medline, Embase and Scopus, and via cross-checking of reference lists. The minimum requirement to be included was the availability of original data and the possibility to construct a two-by-two table. Study selection, critical appraisal using the QUADAS II instrument and extraction of salient study characteristics was made in duplicate. Sensitivity and specificity was computed for each study. We included 11 studies (15 two-by-two tables) of moderate methodological quality enrolling 820 participants (range 30 to 118). In 44.4% participants were female (range 37-59% in specific subgroups). CDI was assessed for internal carotid stenosis, diabetic retinopathy, glaucoma, and branch or central retinal vein occlusion diagnosis. There was insufficient data to pool the results for specific illnesses. For the assessments of ophthalmic arteries, mean sensitivity was 0.69 (range 0.27-0.96) with a corresponding mean specificity of 0.83 (range 0.70-0.96). Mean sensitivity of the central retinal artery assessments was 0.58 (range 0.31-0.84) and the corresponding mean specificity was 0.82 (range 0.63-0.94). Robust assessments of the diagnostic value of colour Doppler analysis remain uncommon, limiting the possibilities to extrapolate its true potential for clinical practice. PROSPERO 2014:CRD42014014027.

  2. Retinal oximetry in patients with ischaemic retinal diseases

    DEFF Research Database (Denmark)

    Rilvén, Sandra; Torp, Thomas Lee; Grauslund, Jakob

    2017-01-01

    The retinal oximeter is a new tool for non-invasive measurement of retinal oxygen saturation in humans. Several studies have investigated the associations between retinal oxygen saturation and retinal diseases. In the present systematic review, we examine whether there are associations between...... retinal oxygen saturation and retinal ischaemic diseases. We used PubMed and Embase to search for retinal oxygen saturation and retinal ischaemic diseases. Three separate searches identified a total of 79 publications. After two levels of manual screening, 10 studies were included: six about diabetic...... retinopathy (DR) and four about retinal vein occlusion. No studies about retinal artery occlusion were included. In diabetes, all studies found that increases in retinal venous oxygen saturation (rvSatO2 ) were associated with present as well as increasing levels of DR. Four of six studies also found...

  3. Optical Coherence Tomography Angiography in Retinal Vascular Diseases and Choroidal Neovascularization

    Directory of Open Access Journals (Sweden)

    Rodolfo Mastropasqua

    2015-01-01

    Full Text Available Purpose. To assess the ability of optical coherence tomography-angiography (OCT-A to show and analyze retinal vascular patterns and the choroidal neovascularization (CNV in retinal vascular diseases. Methods. Seven eyes of seven consecutive patients with retinal vascular diseases were examined. Two healthy subjects served as controls. All eyes were scanned with the SD-OCT XR Avanti (Optovue Inc, Fremont CA, USA. Split spectrum amplitude decorrelation angiography algorithm was used to identify the blood flow within the tissue. Fluorescein angiography (FA and indocyanine green angiography (ICGA with Spectralis HRA + OCT (Heidelberg Engineering GmbH were performed. Results. In healthy subjects OCT-A visualized major macular vessels and detailed capillary networks around the foveal avascular zone. Patients were affected with myopic CNV (2 eyes, age-related macular degeneration related (2, branch retinal vein occlusion (BRVO (2, and branch retinal artery occlusion (BRAO (1. OCT-A images provided distinct vascular patterns, distinguishing perfused and nonperfused areas in BRVO and BRAO and recognizing the presence, location, and size of CNV. Conclusions. OCT-A provides detailed images of retinal vascular plexuses and quantitative data of pathologic structures. Further studies are warranted to define the role of OCT-A in the assessment of retinovascular diseases, with respect to conventional FA and ICG-A.

  4. Detection of hypertensive retinopathy using vessel measurements and textural features.

    Science.gov (United States)

    Agurto, Carla; Joshi, Vinayak; Nemeth, Sheila; Soliz, Peter; Barriga, Simon

    2014-01-01

    Features that indicate hypertensive retinopathy have been well described in the medical literature. This paper presents a new system to automatically classify subjects with hypertensive retinopathy (HR) using digital color fundus images. Our method consists of the following steps: 1) normalization and enhancement of the image; 2) determination of regions of interest based on automatic location of the optic disc; 3) segmentation of the retinal vasculature and measurement of vessel width and tortuosity; 4) extraction of color features; 5) classification of vessel segments as arteries or veins; 6) calculation of artery-vein ratios using the six widest (major) vessels for each category; 7) calculation of mean red intensity and saturation values for all arteries; 8) calculation of amplitude-modulation frequency-modulation (AM-FM) features for entire image; and 9) classification of features into HR and non-HR using linear regression. This approach was tested on 74 digital color fundus photographs taken with TOPCON and CANON retinal cameras using leave-one out cross validation. An area under the ROC curve (AUC) of 0.84 was achieved with sensitivity and specificity of 90% and 67%, respectively.

  5. Novel cellular bouton structure activated by ATP in the vascular wall of porcine retinal arterioles.

    Science.gov (United States)

    Misfeldt, Mikkel Wölck; Aalkjaer, Christian; Simonsen, Ulf; Bek, Toke

    2010-12-01

    The retinal blood flow is regulated by the tone of resistance arterioles, which is influenced by purinergic compounds such as adenosine and adenosine 5'-triphosphate (ATP) released from the retinal tissue. However, it is unknown what cellular elements in the perivascular retina are responsible for the effect of purines on the tone of retinal arterioles. Porcine retinal arterioles were loaded with the calcium-sensitive fluorophore Oregon green. The vessels were mounted in a confocal myograph for simultaneous recordings of tone and calcium activity in cells of the vascular wall during stimulation with ATP and adenosine, with and without modifiers of these compounds. Additionally, immunohistochemistry was used to localize elements with calcium activity in the vascular wall. Hyperfluorescence indicating calcium activity was recorded in a population of abundant round boutons interspersed in a network of vimentin-positive processes located immediately external to the smooth muscle cell layer but internal to the perivascular glial cells. These structures showed calcium activity when the vessel was relaxed with ATP but not when it was relaxed with adenosine. Ryanodine reduced calcium activity in the boutons, whereas the ATP antagonist adenosine-5'-O-(α, β- methylene diphosphate) reduced calcium activity in both the boutons and vascular tone. The vasodilating effect of purines in porcine retinal tissue involves ATP-dependent calcium activity in a layer of cellular boutons located external to the vascular smooth muscle cells and internal to the perivascular glial cells.

  6. Evaluation of the Retinal Vasculature in Hypertension and Chronic Kidney Disease in an Elderly Population of Irish Nuns.

    Directory of Open Access Journals (Sweden)

    Amy McGowan

    Full Text Available Chronic kidney disease (CKD and hypertension are global public health problems associated with considerable morbidity, premature mortality and attendant healthcare costs. Previous studies have highlighted that non-invasive examination of the retinal microcirculation can detect microvascular pathology that is associated with systemic disorders of the circulatory system such as hypertension. We examined the associations between retinal vessel caliber (RVC and fractal dimension (DF, with both hypertension and CKD in elderly Irish nuns.Data from 1233 participants in the cross-sectional observational Irish Nun Eye Study (INES were assessed from digital photographs with a standardized protocol using computer-assisted software. Multivariate regression analyses were used to assess associations with hypertension and CKD, with adjustment for age, body mass index (BMI, refraction, fellow eye RVC, smoking, alcohol consumption, ischemic heart disease (IHD, cerebrovascular accident (CVA, diabetes and medication use.In total, 1122 (91% participants (mean age: 76.3 [range: 56-100] years had gradable retinal images of sufficient quality for blood vessel assessment. Hypertension was significantly associated with a narrower central retinal arteriolar equivalent (CRAE in a fully adjusted analysis (P = 0.002; effect size = -2.16 μm; 95% confidence intervals [CI]: -3.51, -0.81 μm. No significant associations between other retinal vascular parameters and hypertension or between any retinal vascular parameters and CKD were found.Individuals with hypertension have significantly narrower retinal arterioles which may afford an earlier opportunity for tailored prevention and treatment options to optimize the structure and function of the microvasculature, providing additional clinical utility. No significant associations between retinal vascular parameters and CKD were detected.

  7. Retinal Vascular Tortuosity in a Patient with Weill-Marchesani Syndrome

    Directory of Open Access Journals (Sweden)

    Kevin Gallagher

    2011-01-01

    Full Text Available Weill-Marchesani syndrome (WMS is a rare connective tissue disorder with characteristic phenotypic skeletal and ocular manifestations. A 28-year-old myopic female presented with an 8-month history of bilateral blurred vision. On examination, she was noted to be of short stature with brachydactyly. On ocular examination, she was found to be spherophakic with bilateral inferiorly subluxated lenses. Serum and urine homocysteine were normal and a syphilis screen was negative. A diagnosis of Weill-Marchesani syndrome was made. Fundoscopy revealed bilateral tortuous retinal vessels. We report the first illustrated case of retinal vascular tortuosity as an ocular manifestation of Weill-Marchesani syndrome.

  8. Missed retinal breaks in rhegmatogenous retinal detachment

    Directory of Open Access Journals (Sweden)

    Brijesh Takkar

    2016-12-01

    Full Text Available AIM: To evaluate the causes and associations of missed retinal breaks (MRBs and posterior vitreous detachment (PVD in patients with rhegmatogenous retinal detachment (RRD. METHODS: Case sheets of patients undergoing vitreo retinal surgery for RRD at a tertiary eye care centre were evaluated retrospectively. Out of the 378 records screened, 253 were included for analysis of MRBs and 191 patients were included for analysis of PVD, depending on the inclusion criteria. Features of RRD and retinal breaks noted on examination were compared to the status of MRBs and PVD detected during surgery for possible associations. RESULTS: Overall, 27% patients had MRBs. Retinal holes were commonly missed in patients with lattice degeneration while missed retinal tears were associated with presence of complete PVD. Patients operated for cataract surgery were significantly associated with MRBs (P=0.033 with the odds of missing a retinal break being 1.91 as compared to patients with natural lens. Advanced proliferative vitreo retinopathy (PVR and retinal bullae were the most common reasons for missing a retinal break during examination. PVD was present in 52% of the cases and was wrongly assessed in 16%. Retinal bullae, pseudophakia/aphakia, myopia, and horse shoe retinal tears were strongly associated with presence of PVD. Traumatic RRDs were rarely associated with PVD. CONCLUSION: Pseudophakic patients, and patients with retinal bullae or advanced PVR should be carefully screened for MRBs. Though Weiss ring is a good indicator of PVD, it may still be over diagnosed in some cases. PVD is associated with retinal bullae and pseudophakia, and inversely with traumatic RRD.

  9. Hypoxia-induced retinal neovascularization in zebrafish embryos: a potential model of retinopathy of prematurity.

    Science.gov (United States)

    Wu, Yu-Ching; Chang, Chao-Yuan; Kao, Alex; Hsi, Brian; Lee, Shwu-Huey; Chen, Yau-Hung; Wang, I-Jong

    2015-01-01

    Retinopathy of prematurity, formerly known as a retrolental fibroplasia, is a leading cause of infantile blindness worldwide. Retinopathy of prematurity is caused by the failure of central retinal vessels to reach the retinal periphery, creating a nonperfused peripheral retina, resulting in retinal hypoxia, neovascularization, vitreous hemorrhage, vitreoretinal fibrosis, and loss of vision. We established a potential retinopathy of prematurity model by using a green fluorescent vascular endothelium zebrafish transgenic line treated with cobalt chloride (a hypoxia-inducing agent), followed by GS4012 (a vascular endothelial growth factor inducer) at 24 hours postfertilization, and observed that the number of vascular branches and sprouts significantly increased in the central retinal vascular trunks 2-4 days after treatment. We created an angiography method by using tetramethylrhodamine dextran, which exhibited severe vascular leakage through the vessel wall into the surrounding retinal tissues. The quantification of mRNA extracted from the heads of the larvae by using real-time quantitative polymerase chain reaction revealed a twofold increase in vegfaa and vegfr2 expression compared with the control group, indicating increased vascular endothelial growth factor signaling in the hypoxic condition. In addition, we demonstrated that the hypoxic insult could be effectively rescued by several antivascular endothelial growth factor agents such as SU5416, bevacizumab, and ranibizumab. In conclusion, we provide a simple, highly reproducible, and clinically relevant retinopathy of prematurity model based on zebrafish embryos; this model may serve as a useful platform for clarifying the mechanisms of human retinopathy of prematurity and its progression.

  10. Development of an integrated automated retinal surgical laser system.

    Science.gov (United States)

    Barrett, S F; Wright, C H; Oberg, E D; Rockwell, B A; Cain, C; Rylander, H G; Welch, A J

    1996-01-01

    Researchers at the University of Texas and the USAF Academy have worked toward the development of a retinal robotic laser system. The overall goal of this ongoing project is to precisely place and control the depth of laser lesions for the treatment of various retinal diseases such as diabetic retinopathy and retinal tears. Separate low speed prototype subsystems have been developed to control lesion depth using lesion reflectance feedback parameters and lesion placement using retinal vessels as tracking landmarks. Both subsystems have been successfully demonstrated in vivo on pigmented rabbits using an argon continuous wave laser. Preliminary testing on rhesus primate subjects have been accomplished with the CW argon laser and also the ultrashort pulse laser. Recent efforts have concentrated on combining the two subsystems into a single prototype capable of simultaneously controlling both lesion depth and placement. We have designated this combined system CALOSOS for Computer Aided Laser Optics System for Ophthalmic Surgery. Several interesting areas of study have developed in integrating the two subsystems: 1) "doughnut" shaped lesions that occur under certain combinations of laser power, spot size, and irradiation time complicating measurements of central lesion reflectance, 2) the optimal retinal field of view (FOV) to achieve both tracking and lesion parameter control, and 3) development of a hybrid analog/digital tracker using confocal reflectometry to achieve retinal tracking speeds of up to 100 dgs. This presentation will discuss these design issues of this clinically significant prototype system. Details of the hybrid prototype system are provided in "Hybrid Eye Tracking for Computer-Aided Retinal Surgery" at this conference. The paper will close with remaining technical hurdles to clear prior to testing the full-up clinical prototype system.

  11. Human retinal pigment epithelial cell-induced apoptosis in activated T cells

    DEFF Research Database (Denmark)

    Jørgensen, A; Wiencke, A K; la Cour, M

    1998-01-01

    PURPOSE: The immune privilege of the eye has been thought to be dependent on physical barriers and absence of lymphatic vessels. However, the immune privilege may also involve active immunologic processes, as recent studies have indicated. The purpose of the present study was to investigate whether...... human retinal pigment epithelial (RPE) cells can induce apoptosis in activated T cells. METHODS: Fas ligand (FasL) expression was detected by flow cytometry and immunohistochemistry. Cultured RPE cells were cocultured with T-cell lines and peripheral blood lymphocytes for 6 hours to 2 days. Induction...... of apoptosis was detected by 7-amino-actinomycin D and annexin V staining. RESULTS: Retinal pigment epithelial cells expressed FasL and induced apoptosis in activated Fas+ T cells. Blocking of Fas-FasL interaction with antibody strongly inhibited RPE-mediated T-cell apoptosis. Retinal pigment epithelial cells...

  12. THE RELATIONSHIP BETWEEN FOVEAL AVASCULAR ZONE AREA, VESSEL DENSITY, AND CYSTOID CHANGES IN DIABETIC RETINOPATHY, AN OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY STUDY.

    Science.gov (United States)

    Tarassoly, Kia; Miraftabi, Arezoo; Soltan Sanjari, Mostafa; Parvaresh, Mohammad Mehdi

    2017-06-29

    To measure the foveal avascular zone (FAZ) areas and vessel densities of patients with diabetic retinopathy and to study their relationship with diabetic cystoid changes and retinal thickness. Prospective case series of 51 eyes of 31 patients with diabetic retinopathy. The eyes were grouped based on the presence or absence of cystoid edema and evaluated using optical coherence tomography angiography. The FAZ areas and vessel density were compared. The FAZ area at the superficial capillary plexus level was equal between the eyes with and without cystoid edema. Vessel density did not differ as well. There was no correlation with retinal thickness. In eyes with cystoid changes, FAZ area changes at the deep capillary plexus level were difficult to interpret. The FAZ area and vessel density at the superficial capillary plexus level are reproducible and independent of the presence of cystoid edema.

  13. Multiple cell common pressure vessel nickel hydrogen battery

    Science.gov (United States)

    Zagrodnik, Jeffrey P.; Jones, Kenneth R.

    1991-01-01

    A multiple cell common pressure vessel (CPV) nickel hydrogen battery was developed that offers significant weight, volume, cost, and interfacing advantages over the conventional individual pressure vessel (IPV) nickel hydrogen configuration that is currently used for aerospace applications. The baseline CPV design was successfully demonstrated though the testing of a 26 cell prototype, which completed over 7,000 44 percent depth of discharge LEO cycles. Two-cell boilerplate batteries have now exceeded 12,500 LEO cycles in ongoing laboratory tests. CPV batteries using both nominal 5 and 10 inch diameter vessels are currently available. The flexibility of the design allows these diameters to provide a broad capability for a variety of space applications.

  14. Alk2/ACVR1 and Alk3/BMPR1A Provide Essential Function for Bone Morphogenetic Protein-Induced Retinal Angiogenesis.

    Science.gov (United States)

    Lee, Heon-Woo; Chong, Diana C; Ola, Roxana; Dunworth, William P; Meadows, Stryder; Ka, Jun; Kaartinen, Vesa M; Qyang, Yibing; Cleaver, Ondine; Bautch, Victoria L; Eichmann, Anne; Jin, Suk-Won

    2017-04-01

    Increasing evidence suggests that bone morphogenetic protein (BMP) signaling regulates angiogenesis. Here, we aimed to define the function of BMP receptors in regulating early postnatal angiogenesis by analysis of inducible, endothelial-specific deletion of the BMP receptor components Bmpr2 (BMP type 2 receptor), Alk1 (activin receptor-like kinase 1), Alk2 , and Alk3 in mouse retinal vessels. Expression analysis of several BMP ligands showed that proangiogenic BMP ligands are highly expressed in postnatal retinas. Consistently, BMP receptors are also strongly expressed in retina with a distinct pattern. To assess the function of BMP signaling in retinal angiogenesis, we first generated mice carrying an endothelial-specific inducible deletion of Bmpr2 . Postnatal deletion of Bmpr2 in endothelial cells substantially decreased the number of angiogenic sprouts at the vascular front and branch points behind the front, leading to attenuated radial expansion. To identify critical BMPR1s (BMP type 1 receptors) associated with BMPR2 in retinal angiogenesis, we generated endothelial-specific inducible deletion of 3 BMPR1s abundantly expressed in endothelial cells and analyzed the respective phenotypes. Among these, endothelial-specific deletion of either Alk2 / acvr1 or Alk3 / Bmpr1a caused a delay in radial expansion, reminiscent of vascular defects associated with postnatal endothelial-specific deletion of BMPR2, suggesting that ALK2/ACVR1 and ALK3/BMPR1A are likely to be the critical BMPR1s necessary for proangiogenic BMP signaling in retinal vessels. Our data identify BMP signaling mediated by coordination of ALK2/ACVR1, ALK3/BMPR1A, and BMPR2 as an essential proangiogenic cue for retinal vessels. © 2017 The Authors.

  15. Alk2/ACVR1 and Alk3/BMPR1A Provide Essential Function for Bone Morphogenetic Protein Induced Retinal Angiogenesis

    Science.gov (United States)

    Lee, Heon-Woo; Chong, Diana C.; Ola, Roxana; Dunworth, William P.; Meadows, Stryder; Ka, Jun; Kaartinen, Vesa M.; Qyang, Yibing; Cleaver, Ondine; Bautch, Victoria L.; Eichmann, Anne; Jin, Suk-Won

    2017-01-01

    Objective Increasing evidence suggests that Bone Morphogenetic Protein (BMP) signaling regulates angiogenesis. Here, we aimed to define the function of BMP receptors in regulating early post-natal angiogenesis by analysis of inducible, endothelial specific deletion of the BMP receptor components Bmpr2, Alk1, Alk2 and Alk3 in mouse retinal vessels. Approach and Results Expression analysis of several BMP ligands showed that pro-angiogenic BMP ligands are highly expressed in postnatal retinas. Consistently, BMP receptors are also strongly expressed in retina with a distinct pattern. To assess the function of BMP signaling in retinal angiogenesis, we first generated mice carrying an endothelial-specific inducible deletion of BMP Type 2 receptor (Bmpr2). Postnatal deletion of Bmpr2 in endothelial cells substantially decreased the number of angiogenic sprouts at the vascular front and branchpoints behind the front, leading to attenuated radial expansion. To identify critical BMPR1s associated with BMPR2 in retinal angiogenesis, we generated endothelial-specific inducible deletion of three BMPR1s abundantly expressed in endothelial cells and analyzed the respective phenotypes. Among these, endothelial specific deletion of either Alk2/acvr1 or Alk3/Bmpr1a caused a delay in radial expansion, reminiscent of vascular defects associated with postnatal endothelial specific deletion of BMPR2, suggesting that ALK2/ACVR1 and ALK3/BMPR1A are likely to be the critical BMPR1s necessary for pro-angiogenic BMP signaling in retinal vessels. Conclusions Our data identify BMP signaling mediated by coordination of ALK2/ACVR1, ALK3/BMPR1A, and BMPR2 as an essential pro-angiogenic cue for retinal vessels. PMID:28232325

  16. A novel method for retinal optic disc detection using bat meta-heuristic algorithm.

    Science.gov (United States)

    Abdullah, Ahmad S; Özok, Yasa Ekşioğlu; Rahebi, Javad

    2018-05-09

    Normally, the optic disc detection of retinal images is useful during the treatment of glaucoma and diabetic retinopathy. In this paper, the novel preprocessing of a retinal image with a bat algorithm (BA) optimization is proposed to detect the optic disc of the retinal image. As the optic disk is a bright area and the vessels that emerge from it are dark, these facts lead to the selected segments being regions with a great diversity of intensity, which does not usually happen in pathological regions. First, in the preprocessing stage, the image is fully converted into a gray image using a gray scale conversion, and then morphological operations are implemented in order to remove dark elements such as blood vessels, from the images. In the next stage, a bat algorithm (BA) is used to find the optimum threshold value for the optic disc location. In order to improve the accuracy and to obtain the best result for the segmented optic disc, the ellipse fitting approach was used in the last stage to enhance and smooth the segmented optic disc boundary region. The ellipse fitting is carried out using the least square distance approach. The efficiency of the proposed method was tested on six publicly available datasets, MESSIDOR, DRIVE, DIARETDB1, DIARETDB0, STARE, and DRIONS-DB. The optic disc segmentation average overlaps and accuracy was in the range of 78.5-88.2% and 96.6-99.91% in these six databases. The optic disk of the retinal images was segmented in less than 2.1 s per image. The use of the proposed method improved the optic disc segmentation results for healthy and pathological retinal images in a low computation time. Graphical abstract ᅟ.

  17. Assessment of W7-X plasma vessel pressurisation in case of LOCA taking into account in-vessel components

    Energy Technology Data Exchange (ETDEWEB)

    Urbonavičius, E., E-mail: Egidijus.Urbonavicius@lei.lt; Povilaitis, M., E-mail: Mantas.Povilaitis@lei.lt; Kontautas, A., E-mail: Aurimas.Kontautas@lei.lt

    2015-11-15

    Highlights: • Analysis of the vacuum vessel response to the LOCA in W7-X was performed using lumped-parameter codes COCOSYS and ASTEC. • Benchmarking of the results received with two codes provides more confidence in results and helps in identification of possible important differences in the modelling. • The performed analysis answered the questions set in the installed plasma vessel venting system during overpressure of PV in case of 40 mm diameter LOCA in “baking” mode. • Differences in time until opening the burst disk observed in ASTEC and COCOSYS results are caused by differences in heat transfer modelling. - Abstract: This paper presents the analysis of W7-X vacuum vessel response taking into account in-vessel components. A detailed analysis of the vacuum vessel response to the loss of coolant accident was performed using lumped-parameter codes COCOSYS and ASTEC. The performed analysis showed that the installed plasma vessel venting system prevents overpressure of PV in case of 40 mm diameter LOCA in “baking” mode. The performed analysis revealed differences in heat transfer modelling implemented in ASTEC and COCOSYS computer codes, which require further investigation to justify the correct approach for application to fusion facilities.

  18. Assessment of W7-X plasma vessel pressurisation in case of LOCA taking into account in-vessel components

    International Nuclear Information System (INIS)

    Urbonavičius, E.; Povilaitis, M.; Kontautas, A.

    2015-01-01

    Highlights: • Analysis of the vacuum vessel response to the LOCA in W7-X was performed using lumped-parameter codes COCOSYS and ASTEC. • Benchmarking of the results received with two codes provides more confidence in results and helps in identification of possible important differences in the modelling. • The performed analysis answered the questions set in the installed plasma vessel venting system during overpressure of PV in case of 40 mm diameter LOCA in “baking” mode. • Differences in time until opening the burst disk observed in ASTEC and COCOSYS results are caused by differences in heat transfer modelling. - Abstract: This paper presents the analysis of W7-X vacuum vessel response taking into account in-vessel components. A detailed analysis of the vacuum vessel response to the loss of coolant accident was performed using lumped-parameter codes COCOSYS and ASTEC. The performed analysis showed that the installed plasma vessel venting system prevents overpressure of PV in case of 40 mm diameter LOCA in “baking” mode. The performed analysis revealed differences in heat transfer modelling implemented in ASTEC and COCOSYS computer codes, which require further investigation to justify the correct approach for application to fusion facilities.

  19. Enhancement of optic cup detection through an improved vessel kink detection framework

    Science.gov (United States)

    Wong, Damon W. K.; Liu, Jiang; Tan, Ngan Meng; Zhang, Zhuo; Lu, Shijian; Lim, Joo Hwee; Li, Huiqi; Wong, Tien Yin

    2010-03-01

    Glaucoma is a leading cause of blindness. The presence and extent of progression of glaucoma can be determined if the optic cup can be accurately segmented from retinal images. In this paper, we present a framework which improves the detection of the optic cup. First, a region of interest is obtained from the retinal fundus image, and a pallor-based preliminary cup contour estimate is determined. Patches are then extracted from the ROI along this contour. To improve the usability of the patches, adaptive methods are introduced to ensure the patches are within the optic disc and to minimize redundant information. The patches are then analyzed for vessels by an edge transform which generates pixel segments of likely vessel candidates. Wavelet, color and gradient information are used as input features for a SVM model to classify the candidates as vessel or non-vessel. Subsequently, a rigourous non-parametric method is adopted in which a bi-stage multi-resolution approach is used to probe and localize the location of kinks along the vessels. Finally, contenxtual information is used to fuse pallor and kink information to obtain an enhanced optic cup segmentation. Using a batch of 21 images obtained from the Singapore Eye Research Institute, the new method results in a 12.64% reduction in the average overlap error against a pallor only cup, indicating viable improvements in the segmentation and supporting the use of kinks for optic cup detection.

  20. Retinal Vascular Fractals and Microvascular and Macrovascular Complications in Type 1 Diabetes

    DEFF Research Database (Denmark)

    Grauslund, Jakob; Green, Anders; Kawasaki, Ryo

    2010-01-01

    diabetes. DESIGN: Cross-sectional study. PARTICIPANTS: This was a cross-sectional study of 208 long-term surviving type 1 diabetes patients from a population-based Danish cohort identified in 1973. METHODS: Retinal photographs were obtained at a clinical examination in 2007 or 2008. D(f) was measured......, respectively. Median D(f) was 1.4610 (range, 1.3774-1.5188). After adjustments for age, gender, duration of diabetes, systolic blood pressure, and smoking, persons with lower D(f) were more likely to have proliferative retinopathy (odds ratio [OR], 1.45 per standard deviation [SD] decrease in D(f); 95......PURPOSE: Fractal analysis is a method to quantify the geometric pattern and complexity of the retinal vessels. This study examined the association of retinal fractal dimension (D(f)) and microvascular and macrovascular complications in a population-based cohort of Danish patients with type 1...

  1. Bone marrow-derived cells are differentially involved in pathological and physiological retinal angiogenesis in mice

    Energy Technology Data Exchange (ETDEWEB)

    Zou, He [Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto 606-8507 (Japan); Otani, Atsushi, E-mail: otan@kuhp.kyoto-u.ac.jp [Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto 606-8507 (Japan); Oishi, Akio; Yodoi, Yuko; Kameda, Takanori; Kojima, Hiroshi; Yoshimura, Nagahisa [Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto 606-8507 (Japan)

    2010-01-08

    Purpose: Bone marrow-derived cells have been shown to play roles in angiogenesis. Although these cells have been shown to promote angiogenesis, it is not yet clear whether these cells affect all types of angiogenesis. This study investigated the involvement of bone marrow-derived cells in pathological and physiological angiogenesis in the murine retina. Materials and methods: The oxygen-induced retinopathy (OIR) model was used as a retinal angiogenesis model in newborn mice. To block the influence of bone marrow-derived cells, the mice were irradiated with a 4-Gy dose of radiation from a {sup 137}Cs source. Irradiation was performed in four different conditions with radio dense 2-cm thick lead disks; (1) H group, the head were covered with these discs to protect the eyes from radiation; (2) A group, all of the body was covered with these discs; (3) N group, mice were completely unshielded; (4) C group, mice were put in the irradiator but were not irradiated. On P17, the retinal areas showing pathological and physiological retinal angiogenesis were measured and compared to the retinas of nonirradiated mice. Results: Although irradiation induced leukocyte depletion, it did not affect the number of other cell types or body weight. Retinal nonperfusion areas were significantly larger in irradiated mice than in control mice (P < 0.05), indicating that physiological angiogenesis was impaired. However, the formation of tuft-like angiogenesis processes was more prominent in the irradiated mice (P < 0.05), indicating that pathological angiogenesis was intact. Conclusions: Bone marrow-derived cells seem to be differentially involved in the formation of physiological and pathological retinal vessels. Pathological angiogenesis in the murine retina does not require functional bone marrow-derived cells, but these cells are important for the formation of physiological vessels. Our results add a new insight into the pathology of retinal angiogenesis and bolster the hypothesis that

  2. Bone marrow-derived cells are differentially involved in pathological and physiological retinal angiogenesis in mice

    International Nuclear Information System (INIS)

    Zou, He; Otani, Atsushi; Oishi, Akio; Yodoi, Yuko; Kameda, Takanori; Kojima, Hiroshi; Yoshimura, Nagahisa

    2010-01-01

    Purpose: Bone marrow-derived cells have been shown to play roles in angiogenesis. Although these cells have been shown to promote angiogenesis, it is not yet clear whether these cells affect all types of angiogenesis. This study investigated the involvement of bone marrow-derived cells in pathological and physiological angiogenesis in the murine retina. Materials and methods: The oxygen-induced retinopathy (OIR) model was used as a retinal angiogenesis model in newborn mice. To block the influence of bone marrow-derived cells, the mice were irradiated with a 4-Gy dose of radiation from a 137 Cs source. Irradiation was performed in four different conditions with radio dense 2-cm thick lead disks; (1) H group, the head were covered with these discs to protect the eyes from radiation; (2) A group, all of the body was covered with these discs; (3) N group, mice were completely unshielded; (4) C group, mice were put in the irradiator but were not irradiated. On P17, the retinal areas showing pathological and physiological retinal angiogenesis were measured and compared to the retinas of nonirradiated mice. Results: Although irradiation induced leukocyte depletion, it did not affect the number of other cell types or body weight. Retinal nonperfusion areas were significantly larger in irradiated mice than in control mice (P < 0.05), indicating that physiological angiogenesis was impaired. However, the formation of tuft-like angiogenesis processes was more prominent in the irradiated mice (P < 0.05), indicating that pathological angiogenesis was intact. Conclusions: Bone marrow-derived cells seem to be differentially involved in the formation of physiological and pathological retinal vessels. Pathological angiogenesis in the murine retina does not require functional bone marrow-derived cells, but these cells are important for the formation of physiological vessels. Our results add a new insight into the pathology of retinal angiogenesis and bolster the hypothesis that bone

  3. Damage threshold from large retinal spot size repetitive-pulse laser exposures.

    Science.gov (United States)

    Lund, Brian J; Lund, David J; Edsall, Peter R

    2014-10-01

    The retinal damage thresholds for large spot size, multiple-pulse exposures to a Q-switched, frequency doubled Nd:YAG laser (532 nm wavelength, 7 ns pulses) have been measured for 100 μm and 500 μm retinal irradiance diameters. The ED50, expressed as energy per pulse, varies only weakly with the number of pulses, n, for these extended spot sizes. The previously reported threshold for a multiple-pulse exposure for a 900 μm retinal spot size also shows the same weak dependence on the number of pulses. The multiple-pulse ED50 for an extended spot-size exposure does not follow the n dependence exhibited by small spot size exposures produced by a collimated beam. Curves derived by using probability-summation models provide a better fit to the data.

  4. Quantification of rat retinal growth and vascular population changes after single and split doses of proton irradiation: translational study using stereology methods

    Science.gov (United States)

    Mao, Xiao W.; Archambeau, John O.; Kubinova, Lucie; Boyle, Soames; Petersen, Georgia; Grove, Roger; Nelson, G. A. (Principal Investigator)

    2003-01-01

    This study quantified architectural and population changes in the rat retinal vasculature after proton irradiation using stereology. A 100 MeV conformal proton beam delivered 8, 14, 20 and 28 Gy as single and split doses to the whole eye. The vascular networks were prepared from retinal digests. Stereological methods were used to obtain the area of the retina and unbiased estimates of microvessel/artery/vein endothelial, pericyte and smooth muscle population, and vessel length. The retinal area increased progressively in the unirradiated, age-matched controls and in the retinas irradiated with 8 and 14 Gy, indicating uniform progressive retinal growth. No growth occurred after 20 and 28 Gy. Regression analysis of total endothelial cell number in all vessels (arteries, veins and capillaries) after irradiation documented a progressive time- and dose-dependent cell loss occurring over 15 to 24 months. The difference from controls was significant (Ppopulations after split doses. At 10 Gy, the rate of endothelial cell loss, a dose parameter used to characterize the time- and dose-dependent loss of the endothelial population, was doubled.

  5. Heissdampfreaktor (HDR) steel-containment-vessel and floodwater-storage-tank structural-dynamics tests

    International Nuclear Information System (INIS)

    Arendts, J.G.

    1982-01-01

    Inertance (vibration) testing of two significant vessels at the Heissdampfreaktor (HDR) facility, located near Kahl, West Germany, was recently completed. Transfer functions were obtained for determination of the modal properties (frequencies, mode shapes and damping) of the vessels using two different test methods for comparative purposes. One of the vessels tested was the steel containment vessel (SCV). The SCV is approximately 180 feet high and 65 feet in diameter with a 1.2-inch wall thickness. The other vessel, called the floodwater storage tank (FWST), is a vertically standing vessel approximately 40 feet high and 10 feet in diameter with a 1/2-inch wall thickness. The FWST support skirt is square (in plan views) with its corners intersecting the ellipsoidal bottom head near the knuckle region

  6. Concurrent OCT imaging of stimulus evoked retinal neural activation and hemodynamic responses

    Science.gov (United States)

    Son, Taeyoon; Wang, Benquan; Lu, Yiming; Chen, Yanjun; Cao, Dingcai; Yao, Xincheng

    2017-02-01

    It is well established that major retinal diseases involve distortions of the retinal neural physiology and blood vascular structures. However, the details of distortions in retinal neurovascular coupling associated with major eye diseases are not well understood. In this study, a multi-modal optical coherence tomography (OCT) imaging system was developed to enable concurrent imaging of retinal neural activity and vascular hemodynamics. Flicker light stimulation was applied to mouse retinas to evoke retinal neural responses and hemodynamic changes. The OCT images were acquired continuously during the pre-stimulation, light-stimulation, and post-stimulation phases. Stimulus-evoked intrinsic optical signals (IOSs) and hemodynamic changes were observed over time in blood-free and blood regions, respectively. Rapid IOSs change occurred almost immediately after stimulation. Both positive and negative signals were observed in adjacent retinal areas. The hemodynamic changes showed time delays after stimulation. The signal magnitudes induced by light stimulation were observed in blood regions and did not show significant changes in blood-free regions. These differences may arise from different mechanisms in blood vessels and neural tissues in response to light stimulation. These characteristics agreed well with our previous observations in mouse retinas. Further development of the multimodal OCT may provide a new imaging method for studying how retinal structures and metabolic and neural functions are affected by age-related macular degeneration (AMD), glaucoma, diabetic retinopathy (DR), and other diseases, which promises novel noninvasive biomarkers for early disease detection and reliable treatment evaluations of eye diseases.

  7. A patient with acute macular neuroretinopathy and central retinal vein occlusion

    Directory of Open Access Journals (Sweden)

    Hirooka K

    2013-07-01

    Full Text Available Kiriko Hirooka,1 Wataru Saito,1,2 Kousuke Noda,1,2 Susumu Ishida1,21Department of Ophthalmology, Hokkaido University Graduate School of Medicine, Sapporo, Japan; 2Department of Ocular Circulation and Metabolism, Hokkaido University Graduate School of Medicine, Sapporo, JapanPurpose: The precise mechanism causing acute macular neuroretinopathy (AMN is still unknown. A recent report suggested that choroidal circulation impairment correlates with its pathogenesis. We report a rare case with simultaneous onset of AMN and central retinal vein occlusion (CRVO, which is a retinal circulation disorder.Methods: Case report.Results: A 44-year-old woman complained of central visual loss of the left eye for the previous 2 weeks. The patient’s visual acuity was 0.5 in the left eye (OS. Fundoscopic examination revealed a wedge-shaped, dark reddish-brown lesion at the macula, and CRVO-like retinal hemorrhages OS. Fluorescein angiography revealed retinal vasculitis and hypofluorescence corresponding to the macular lesion. The patient’s scanning laser ophthalmoscopy infrared imaging result led to a diagnosis of AMN. Two weeks after corticosteroid pulse therapy, her visual acuity improved to 1.2 OS, with improvement of macular findings and Humphrey perimetry. When the dose of oral corticosteroid was decreased, the AMN lesion worsened, with recurrence of retinal hemorrhages. Visual functions improved again after an increased dose of corticosteroid.Conclusion: These results suggest that circulatory disorders almost simultaneously occurred in choroidal and retinal vessels, resulting in the onset of both AMN and CRVO.Keywords: choroidal circulation, optical coherence tomography, retinal circulation, systemic corticosteroid therapy

  8. ROCK-1 mediates diabetes-induced retinal pigment epithelial and endothelial cell blebbing: Contribution to diabetic retinopathy.

    Science.gov (United States)

    Rothschild, Pierre-Raphaël; Salah, Sawsen; Berdugo, Marianne; Gélizé, Emmanuelle; Delaunay, Kimberley; Naud, Marie-Christine; Klein, Christophe; Moulin, Alexandre; Savoldelli, Michèle; Bergin, Ciara; Jeanny, Jean-Claude; Jonet, Laurent; Arsenijevic, Yvan; Behar-Cohen, Francine; Crisanti, Patricia

    2017-08-18

    In diabetic retinopathy, the exact mechanisms leading to retinal capillary closure and to retinal barriers breakdown remain imperfectly understood. Rho-associated kinase (ROCK), an effector of the small GTPase Rho, involved in cytoskeleton dynamic regulation and cell polarity is activated by hyperglycemia. In one year-old Goto Kakizaki (GK) type 2 diabetic rats retina, ROCK-1 activation was assessed by its cellular distribution and by phosphorylation of its substrates, MYPT1 and MLC. In both GK rat and in human type 2 diabetic retinas, ROCK-1 is activated and associated with non-apoptotic membrane blebbing in retinal vessels and in retinal pigment epithelium (RPE) that respectively form the inner and the outer barriers. Activation of ROCK-1 induces focal vascular constrictions, endoluminal blebbing and subsequent retinal hypoxia. In RPE cells, actin cytoskeleton remodeling and membrane blebs in RPE cells contributes to outer barrier breakdown. Intraocular injection of fasudil, significantly reduces both retinal hypoxia and RPE barrier breakdown. Diabetes-induced cell blebbing may contribute to ischemic maculopathy and represent an intervention target.

  9. Eye Morphology and Retinal Topography in Hummingbirds (Trochilidae: Aves).

    Science.gov (United States)

    Lisney, Thomas J; Wylie, Douglas R; Kolominsky, Jeffrey; Iwaniuk, Andrew N

    2015-01-01

    Hummingbirds are a group of small, highly specialized birds that display a range of adaptations to their nectarivorous lifestyle. Vision plays a key role in hummingbird feeding and hovering behaviours, yet very little is known about the visual systems of these birds. In this study, we measured eye morphology in 5 hummingbird species. For 2 of these species, we used stereology and retinal whole mounts to study the topographic distribution of neurons in the ganglion cell layer. Eye morphology (expressed as the ratio of corneal diameter to eye transverse diameter) was similar among all 5 species and was within the range previously documented for diurnal birds. Retinal topography was similar in Amazilia tzacatl and Calypte anna. Both species had 2 specialized retinal regions of high neuron density: a central region located slightly dorso-nasal to the superior pole of the pecten, where densities reached ∼ 45,000 cells · mm(-2), and a temporal area with lower densities (38,000-39,000 cells · mm(-2)). A weak visual streak bridged the two high-density areas. A retina from Phaethornis superciliosus also had a central high-density area with a similar peak neuron density. Estimates of spatial resolving power for all 3 species were similar, at approximately 5-6 cycles · degree(-1). Retinal cross sections confirmed that the central high-density region in C. anna contains a fovea, but not the temporal area. We found no evidence of a second, less well-developed fovea located close to the temporal retina margin. The central and temporal areas of high neuron density allow for increased spatial resolution in the lateral and frontal visual fields, respectively. Increased resolution in the frontal field in particular may be important for mediating feeding behaviors such as aerial docking with flowers and catching small insects. © 2015 S. Karger AG, Basel.

  10. Congenital Retinal Macrovessel and the Association of Retinal Venous Malformations With Venous Malformations of the Brain.

    Science.gov (United States)

    Pichi, Francesco; Freund, K Bailey; Ciardella, Antonio; Morara, Mariachiara; Abboud, Emad B; Ghazi, Nicola; Dackiw, Christine; Choudhry, Netan; Souza, Eduardo Cunha; Cunha, Leonardo Provetti; Arevalo, J Fernando; Liu, T Y Alvin; Wenick, Adam; He, Lingmin; Villarreal, Guadalupe; Neri, Piergiorgio; Sarraf, David

    2018-04-01

    Congenital retinal macrovessel (CRM) is a rarely reported venous malformation of the retina that is associated with venous anomalies of the brain. To study the multimodal imaging findings of a series of eyes with congenital retinal macrovessel and describe the systemic associations. In this cross-sectional multicenter study, medical records were retrospectively reviewed from 7 different retina clinics worldwide over a 10-year period (2007-2017). Patients with CRM, defined as an abnormal, large, macular vessel with a vascular distribution above and below the horizontal raphe, were identified. Data were analyzed from December 2016 to August 2017. Clinical information and multimodal retinal imaging findings were collected and studied. Pertinent systemic information, including brain magnetic resonance imaging findings, was also noted if available. Of the 49 included patients, 32 (65%) were female, and the mean (SD) age at onset was 44.0 (20.9) years. A total of 49 eyes from 49 patients were studied. Macrovessel was unilateral in all patients. Color fundus photography illustrated a large aberrant dilated and tortuous retinal vein in all patients. Early-phase frames of fluorescein angiography further confirmed the venous nature of the macrovessel in 40 of 40 eyes. Optical coherence tomography angiography, available in 17 eyes (35%), displayed microvascular capillary abnormalities around the CRM, which were more evident in the deep capillary plexus. Of the 49 patients with CRM, 39 (80%) did not illustrate any evidence of ophthalmic complications. Ten patients (20%) presented with retinal complications, typically an incidental association with CRM. Twelve patients (24%) were noted to have venous malformations of the brain with associated magnetic resonance imaging. Of these, location of the venous anomaly in the brain was ipsilateral to the CRM in 10 patients (83%) and contralateral in 2 patients (17%), mainly located in the frontal lobe in 9 patients (75%). Our study has

  11. Progressive outer retinal necrosis-like retinitis in immunocompetent hosts.

    Science.gov (United States)

    Chawla, Rohan; Tripathy, Koushik; Gogia, Varun; Venkatesh, Pradeep

    2016-08-10

    We describe two young immunocompetent women presenting with bilateral retinitis with outer retinal necrosis involving posterior pole with centrifugal spread and multifocal lesions simulating progressive outer retinal necrosis (PORN) like retinitis. Serology was negative for HIV and CD4 counts were normal; however, both women were on oral steroids at presentation for suspected autoimmune chorioretinitis. The retinitis in both eyes responded well to oral valaciclovir therapy. However, the eye with the more fulminant involvement developed retinal detachment with a loss of vision. Retinal atrophy was seen in the less involved eye with preservation of vision. Through these cases, we aim to describe a unique evolution of PORN-like retinitis in immunocompetent women, which was probably aggravated by a short-term immunosuppression secondary to oral steroids. 2016 BMJ Publishing Group Ltd.

  12. Fluid-solid contact vessel having fluid distributors therein

    Science.gov (United States)

    Jones, Jr., John B.

    1980-09-09

    Rectangularly-shaped fluid distributors for large diameter, vertical vessels include reinforcers for high heat operation, vertical sides with gas distributing orifices and overhanging, sloped roofs. Devices are provided for cleaning the orifices from a buildup of solid deposits resulting from the reactions in the vessel.

  13. Construction of tissue-engineered small-diameter vascular grafts in fibrin scaffolds in 30 days.

    Science.gov (United States)

    Gui, Liqiong; Boyle, Michael J; Kamin, Yishai M; Huang, Angela H; Starcher, Barry C; Miller, Cheryl A; Vishnevetsky, Michael J; Niklason, Laura E

    2014-05-01

    Tissue-engineered small-diameter vascular grafts have been developed as a promising alternative to native veins or arteries for replacement therapy. However, there is still a crucial need to improve the current approaches to render the tissue-engineered blood vessels more favorable for clinical applications. A completely biological blood vessel (3-mm inner diameter) was constructed by culturing a 50:50 mixture of bovine smooth muscle cells (SMCs) with neonatal human dermal fibroblasts in fibrin gels. After 30 days of culture under pulsatile stretching, the engineered blood vessels demonstrated an average burst pressure of 913.3±150.1 mmHg (n=6), a suture retention (53.3±15.4 g) that is suitable for implantation, and a compliance (3.1%±2.5% per 100 mmHg) that is comparable to native vessels. These engineered grafts contained circumferentially aligned collagen fibers, microfibrils and elastic fibers, and differentiated SMCs, mimicking a native artery. These promising mechanical and biochemical properties were achieved in a very short culture time of 30 days, suggesting the potential of co-culturing SMCs with fibroblasts in fibrin gels to generate functional small-diameter vascular grafts for vascular reconstruction surgery.

  14. Neovascular Glaucoma Induced by Peripheral Retinal Ischemia in Neurofibromatosis Type 1: Management and Imaging Features

    Directory of Open Access Journals (Sweden)

    Francesco Pichi

    2013-04-01

    Full Text Available Purpose: To report the case of a young patient affected by neurofibromatosis 1 (NF-1 with peripheral retinal ischemia-induced neovascular glaucoma and the peculiar spectral-domain optical coherence tomography (SD-OCT features. Material and Methods: A 13-year-old boy affected by NF-1, as diagnosed according to established criteria, was referred with a diagnosis of hypertensive uveitis in his left eye. He underwent a complete ophthalmic examination and comprehensive blood work with viral and immunological tests. The case was documented with fluorescein angiography (FA and SD-OCT. When the intraocular pressure (IOP of the left eye decreased and the cornea cleared, FA revealed retinal ischemia and leakage from pathologic retinal vessels. SD-OCT revealed foveal hypoplasia secondary to the complete absence of the retinal nerve fiber layer. Results: Peripheral retinal ischemia-induced neovascular glaucoma was diagnosed. The patient underwent Ahmed valve implantation to control his IOP, and subsequent retinal photocoagulation by argon laser and intravitreal bevacizumab injection were performed to control neovascularization. Discussion: Retinal ischemia in NF-1 might lead to neovascular glaucoma: lowering of the IOP with surgical implantation of an Ahmed valve, regression of neovascularization by argon laser panretinal photocoagulation and intravitreal injection of bevacizumab can be a helpful way to control such a complication.

  15. Retinal Vasculitis

    Science.gov (United States)

    Rosenbaum, James T.; Sibley, Cailin H.; Lin, Phoebe

    2016-01-01

    Purpose of review Ophthalmologists and rheumatologists frequently miscommunicate in consulting on patients with retinal vasculitis. This report seeks to establish a common understanding of the term, retinal vasculitis, and to review recent papers on this diagnosis. Recent findings 1) The genetic basis of some rare forms of retinal vascular disease have recently been described. Identified genes include CAPN5, TREX1, and TNFAIP3; 2) Behçet’s disease is a systemic illness that is very commonly associated with occlusive retinal vasculitis; 3) retinal imaging including fluorescein angiography and other newer imaging modalities has proven crucial to the identification and characterization of retinal vasculitis and its complications; 4) although monoclonal antibodies to IL-17A or IL-1 beta failed in trials for Behçet’s disease, antibodies to TNF alpha, either infliximab or adalimumab, have demonstrated consistent benefit in managing this disease. Interferon treatment and B cell depletion therapy via rituximab may be beneficial in certain types of retinal vasculitis. Summary Retinal vasculitis is an important entity for rheumatologists to understand. Retinal vasculitis associated with Behçet’s disease responds to monoclonal antibodies that neutralize TNF, but the many other forms of non-infectious retinal vasculitis may require alternate therapeutic management. PMID:26945335

  16. Temporal changes in retinal vascular parameters associated with successful panretinal photocoagulation in proliferative diabetic retinopathy

    DEFF Research Database (Denmark)

    Torp, Thomas Lee; Kawasaki, Ryo; Wong, Tien Yin

    2018-01-01

    PURPOSE: We aimed to investigate changes in retinal vascular geometry over time after panretinal photocoagulation (PRP) in patients with proliferative diabetic retinopathy (PDR). METHODS: Thirty-seven eyes with PDR were included. Wide-field fluorescein angiography (Optomap, Optos PLC., Dunfermline......, Scotland, UK) was used to diagnose PDR at baseline and to assess activity at follow-up month three and six. At each time-point, a trained grader measured retinal vessel geometry on optic disc (OD) centred images using semiautomated software (SIVA, Singapore I Vessel Assessment, National University...... of Singapore, Singapore) according to a standardized protocol. RESULTS: At baseline, the mean age and duration of diabetes were 52.8 and 22.3 years, and 65% were male. Mean HbA1c was 69.9 mmol/mol, and blood pressure was 155/84 mmHg. Of the 37 eyes with PDR, eight (22%) eyes had progression at month three...

  17. Automatic Segmentation of Vessels in In-Vivo Ultrasound Scans

    DEFF Research Database (Denmark)

    Tamimi-Sarnikowski, Philip; Brink-Kjær, Andreas; Moshavegh, Ramin

    2017-01-01

    presents a fully automatic segmentation algorithm, for robustly segmenting the vessel lumen in longitudinal B-mode ultrasound images. The automatic segmentation is performed using a combination of B-mode and power Doppler images. The proposed algorithm includes a series of preprocessing steps, and performs......Ultrasound has become highly popular to monitor atherosclerosis, by scanning the carotid artery. The screening involves measuring the thickness of the vessel wall and diameter of the lumen. An automatic segmentation of the vessel lumen, can enable the determination of lumen diameter. This paper...... a vessel segmentation by use of the marker-controlled watershed transform. The ultrasound images used in the study were acquired using the bk3000 ultrasound scanner (BK Ultrasound, Herlev, Denmark) with two transducers ”8L2 Linear” and ”10L2w Wide Linear” (BK Ultrasound, Herlev, Denmark). The algorithm...

  18. Transplanting Retinal Cells using Bucky Paper for Support

    Science.gov (United States)

    Loftus, David J.; Cinke, Martin; Meyyappan, Meyya; Fishman, Harvey; Leng, Ted; Huie, Philip; Bilbao, Kalayaan

    2004-01-01

    A novel treatment for retinal degenerative disorders involving transplantation of cells into the eye is currently under development at NASA Ames Research Center and Stanford University School of Medicine. The technique uses bucky paper as a support material for retinal pigment epithelial (RPE) cells, iris pigment epithelial (IPE) cells, and/or stem cells. This technology is envisioned as a treatment for age-related macular degeneration, which is the leading cause of blindness in persons over age 65 in Western nations. Additionally, patients with other retinal degenerative disorders, such as retinitis pigmentosa, may be treated by this strategy. Bucky paper is a mesh of carbon nanotubes (CNTs), as shown in Figure 1, that can be made from any of the commercial sources of CNTs. Bucky paper is biocompatible and capable of supporting the growth of biological cells. Because bucky paper is highly porous, nutrients, oxygen, carbon dioxide, and waste can readily diffuse through it. The thickness, density, and porosity of bucky paper can be tailored in manufacturing. For transplantation of cells into the retina, bucky paper serves simultaneously as a substrate for cell growth and as a barrier for new blood vessel formation, which can be a problem in the exudative type of macular degeneration. Bucky paper is easily handled during surgical implantation into the eye. Through appropriate choice of manufacturing processes, bucky paper can be made relatively rigid yet able to conform to the retina when the bucky paper is implanted. Bucky paper offers a distinct advantage over other materials that have been investigated for retinal cell transplantation - lens capsule and Descemet's membrane - which are difficult to handle during surgery because they are flimsy and do not stay flat.

  19. The application of optical coherence tomography angiography in retinal diseases.

    Science.gov (United States)

    Sambhav, Kumar; Grover, Sandeep; Chalam, Kakarla V

    Optical coherence tomography angiography (OCTA) is a new, noninvasive imaging technique that generates real-time volumetric data on chorioretinal vasculature and its flow pattern. With the advent of high-speed optical coherence tomography, established enface chorioretinal segmentation, and efficient algorithms, OCTA generates images that resemble an angiogram. The principle of OCTA involves determining the change in backscattering between consecutive B-scans and then attributing the differences to the flow of erythrocytes through retinal blood vessels. OCTA has shown promise in the evaluation of common ophthalmologic diseases such as diabetic retinopathy, age-related macular degeneration, and retinal vascular occlusions. It quantifies vascular compromise reflecting the severity of diabetic retinopathy. OCTA detects the presence of choroidal neovascularization in exudative age-related macular degeneration and maps loss of choriocapillaris in nonexudative age-related macular degeneration. We describe principles of OCTA and findings in common and some uncommon retinal pathologies. Finally, we summarize its potential future applications. Its current limitations include a relatively small field of view, inability to show leakage, and a tendency for image artifacts. Further larger studies will define OCTAs utility in clinical settings and establish if the technology may offer its utility in decreasing morbidity through early detection and guide therapeutic interventions in retinal diseases. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Short-term poor glycemic control and retinal microvascular changes in pediatric Type 1 Diabetes patients in Singapore: a pilot study.

    Science.gov (United States)

    Li, Ling-Jun; Lamoureux, Ecosse; Wong, Tien Yin; Lek, Ngee

    2017-06-15

    Poor glycemic control in Type 1 Diabetes (T1D) patients is strongly associated with an increased risk of diabetes-related microvascular complications later in life, but it is unclear whether short period of poor glycemic control in children with T1D can cause evident microvascular morphological changes long before any pathological manifestation. Our study aimed to investigate the longitudinal association between poor glycemic control and subsequent changes in retinal microvasculature, in a pilot study of 55 pediatric T1D patients from Singapore after a one-year follow-up. This is a hospital-based, exposure-matched and retrospective longitudinal study. A total of 55 T1D patients were included from Singapore KK Women's and Children Hospital, 28 of whom had poor glycemic control (average glycated hemoglobin [HbA1c] ≥8% during the year) while the other 27 age- and gender-matched subjects had good glycemic control (HbA1c Singapore I Vessel Assessment [SIVA], version 4.0, Singapore Eye Research Institute, Singapore) and a spectrum of retinal vascular parameters (e.g. caliber, tortuosity, branching angle and fractal dimension) were measured quantitatively from 0.5 to 2.0 disc diameters. There was no significant difference in ethnicity, duration of T1D, blood pressure, body mass index (BMI) and low-density cholesterol lipoprotein (LDL) between the two groups. Retinal imaging was obtained at the end of 1 year of glycemic control assessment. In multiple linear regression adjusting for ethnicity, BMI, LDL and duration of T1D, patients with poor glycemic control tended to have marginally wider retinal arteriolar caliber (6.0 μm, 95% CI: -0.9, 12.8) and had significantly larger retinal arteriolar branching angle (10.1 degrees, 95% CI: 1.4, 18.9) compared with their age- and gender- matched counterparts with good glycemic control. Our findings showed that abnormal retinal microvascular morphology was evident in pediatric patients with T1D after one-year's poor glycemic

  1. Noninvasive, in vivo assessment of mouse retinal structure using optical coherence tomography.

    Directory of Open Access Journals (Sweden)

    M Dominik Fischer

    Full Text Available BACKGROUND: Optical coherence tomography (OCT is a novel method of retinal in vivo imaging. In this study, we assessed the potential of OCT to yield histology-analogue sections in mouse models of retinal degeneration. METHODOLOGY/PRINCIPAL FINDINGS: We achieved to adapt a commercial 3(rd generation OCT system to obtain and quantify high-resolution morphological sections of the mouse retina which so far required in vitro histology. OCT and histology were compared in models with developmental defects, light damage, and inherited retinal degenerations. In conditional knockout mice deficient in retinal retinoblastoma protein Rb, the gradient of Cre expression from center to periphery, leading to a gradual reduction of retinal thickness, was clearly visible and well topographically quantifiable. In Nrl knockout mice, the layer involvement in the formation of rosette-like structures was similarly clear as in histology. OCT examination of focal light damage, well demarcated by the autofluorescence pattern, revealed a practically complete loss of photoreceptors with preservation of inner retinal layers, but also more subtle changes like edema formation. In Crb1 knockout mice (a model for Leber's congenital amaurosis, retinal vessels slipping through the outer nuclear layer towards the retinal pigment epithelium (RPE due to the lack of adhesion in the subapical region of the photoreceptor inner segments could be well identified. CONCLUSIONS/SIGNIFICANCE: We found that with the OCT we were able to detect and analyze a wide range of mouse retinal pathology, and the results compared well to histological sections. In addition, the technique allows to follow individual animals over time, thereby reducing the numbers of study animals needed, and to assess dynamic processes like edema formation. The results clearly indicate that OCT has the potential to revolutionize the future design of respective short- and long-term studies, as well as the preclinical

  2. A model for ultrasound contrast agent in a phantom vessel

    KAUST Repository

    Qamar, Adnan

    2014-02-01

    A theoretical framework to model the dynamics of Ultrasound Contrast Agent (UCA) inside a phantom vessel is presented. The model is derived from the reduced Navier-Stokes equation and is coupled with the evolving flow field solution inside the vessel by a similarity transformation approach. The results are computed, and compared with experiments available in literature, for the initial UCA radius of Ro=1.5 μm and 2 μm for the vessel diameter of D=12 μm and 200 μm with the acoustic parameters as utilized in the experiments. When compared to other models, better agreement on smaller vessel diameter is obtained with the proposed coupled model. The model also predicts, quite accurately, bubble fragmentation in terms of acoustic and geometric parameters. © 2014 IEEE.

  3. Comprehensive automatic assessment of retinal vascular abnormalities for computer-assisted retinopathy grading.

    Science.gov (United States)

    Joshi, Vinayak; Agurto, Carla; VanNess, Richard; Nemeth, Sheila; Soliz, Peter; Barriga, Simon

    2014-01-01

    One of the most important signs of systemic disease that presents on the retina is vascular abnormalities such as in hypertensive retinopathy. Manual analysis of fundus images by human readers is qualitative and lacks in accuracy, consistency and repeatability. Present semi-automatic methods for vascular evaluation are reported to increase accuracy and reduce reader variability, but require extensive reader interaction; thus limiting the software-aided efficiency. Automation thus holds a twofold promise. First, decrease variability while increasing accuracy, and second, increasing the efficiency. In this paper we propose fully automated software as a second reader system for comprehensive assessment of retinal vasculature; which aids the readers in the quantitative characterization of vessel abnormalities in fundus images. This system provides the reader with objective measures of vascular morphology such as tortuosity, branching angles, as well as highlights of areas with abnormalities such as artery-venous nicking, copper and silver wiring, and retinal emboli; in order for the reader to make a final screening decision. To test the efficacy of our system, we evaluated the change in performance of a newly certified retinal reader when grading a set of 40 color fundus images with and without the assistance of the software. The results demonstrated an improvement in reader's performance with the software assistance, in terms of accuracy of detection of vessel abnormalities, determination of retinopathy, and reading time. This system enables the reader in making computer-assisted vasculature assessment with high accuracy and consistency, at a reduced reading time.

  4. Vessel discoloration detection in malarial retinopathy

    Science.gov (United States)

    Agurto, C.; Nemeth, S.; Barriga, S.; Soliz, P.; MacCormick, I.; Taylor, T.; Harding, S.; Lewallen, S.; Joshi, V.

    2016-03-01

    Cerebral malaria (CM) is a life-threatening clinical syndrome associated with malarial infection. It affects approximately 200 million people, mostly sub-Saharan African children under five years of age. Malarial retinopathy (MR) is a condition in which lesions such as whitening and vessel discoloration that are highly specific to CM appear in the retina. Other unrelated diseases can present with symptoms similar to CM, therefore the exact nature of the clinical symptoms must be ascertained in order to avoid misdiagnosis, which can lead to inappropriate treatment and, potentially, death. In this paper we outline the first system to detect the presence of discolored vessels associated with MR as a means to improve the CM diagnosis. We modified and improved our previous vessel segmentation algorithm by incorporating the `a' channel of the CIELab color space and noise reduction. We then divided the segmented vasculature into vessel segments and extracted features at the wall and in the centerline of the segment. Finally, we used a regression classifier to sort the segments into discolored and not-discolored vessel classes. By counting the abnormal vessel segments in each image, we were able to divide the analyzed images into two groups: normal and presence of vessel discoloration due to MR. We achieved an accuracy of 85% with sensitivity of 94% and specificity of 67%. In clinical practice, this algorithm would be combined with other MR retinal pathology detection algorithms. Therefore, a high specificity can be achieved. By choosing a different operating point in the ROC curve, our system achieved sensitivity of 67% with specificity of 100%.

  5. Normal ureteral diameter in infancy and childhood

    International Nuclear Information System (INIS)

    Hellstroem, M.; Hjaelmaas, K.; Jacobsson, B.; Jodal, U.; Oden, A.; Oestra Sjukhuset, Goeteborg; Oestra Sjukhuset, Goeteborg; Goeteborg Univ.

    1985-01-01

    Ureteral diameters were estimated on films from intravenous urography in 194 children (100 boys and 94 girls) aged 0-16 years. Children with signs of urinary tract infection, calculi, obstruction, duplication or malformation were excluded. Films obtained without abdominal compression were used for measurements, including only ureters visualized over 50 per cent of their lengths. A good correlation was demonstrated between ureteral diameter and age and between ureteral diameter and the length of a segment of the lumbar spine. The widest part of the ureter was most often located just above the crossing of the iliac vessels. The right ureter was slightly wider than the left one. No difference between boys and girls was noted. The results are in good agreement with those of others obtained at autopsy. Bearing in mind the possible physiologic variations, it would seem that measuring the ureteral diameter can be of value for a more objective differentiation between dilated and non-dilated ureters. (orig.)

  6. Hyperoxia-Induced Proliferative Retinopathy: Early Interruption of Retinal Vascular Development with Severe and Irreversible Neurovascular Disruption.

    Directory of Open Access Journals (Sweden)

    Michelle Lajko

    Full Text Available Bronchopulmonary dysplasia (BPD is a major cause of neonatal morbidity in premature infants, occurring as a result of arrested lung development combined with multiple postnatal insults. Infants with BPD exposed to supplemental oxygen are at risk of retinopathy of prematurity as well. Thus, we studied the effects of hyperoxia on the retinal vasculature in a murine model of BPD. The retinal phenotype of this model, which we termed hyperoxia-induced proliferative retinopathy (HIPR, shows severe disruption of retinal vasculature and loss of vascular patterning, disorganized intra-retinal angiogenesis, inflammation and retinal detachment. Neonatal mice were subjected to 75% oxygen exposure from postnatal day (P0 to P14 to model BPD, then allowed to recover in room air for 1 (P15, 7 (P21, or 14 days (P28. We quantified retinal thickness, protein levels of HIF-1α, NOX2, and VEGF, and examined the cellular locations of these proteins by immunohistochemistry. We examined the retinal blood vessel integrity and inflammatory markers, including macrophages (F4/80 and lymphocytes (CD45R. Compared to controls, normal retinal vascular development was severely disrupted and replaced by a disorganized sheet of intra-retinal angiogenesis in the HIPR mice. At all time-points, HIPR showed persistent hyaloidal vasculature and a significantly thinner central retina compared to controls. HIF-1α protein levels were increased at P15, while VEGF levels continued to increase until P21. Intra-retinal fibrinogen was observed at P21 followed by sub-retinal deposition in at P28. Inflammatory lymphocytes and macrophages were observed at P21 and P28, respectively. This model presents a severe phenotype of disrupted retinal vascular development, intra-retinal angiogenesis inflammation and retinal detachment.

  7. Selective Thinning of the Perifoveal Inner Retina as an Early Sign of Hydroxychloroquine Retinal Toxicity

    Science.gov (United States)

    Pasadhika, Sirichai; Fishman, Gerald A; Choi, Dongseok; Shahidi, Mahnaz

    2013-01-01

    Purpose To evaluate macular thickness profiles using spectral-domain optical coherence tomography (SDOCT) and image segmentation in patients with chronic exposure to hydroxychloroquine. Methods This study included 8 patients with chronic exposure to hydroxychloroquine (Group 1) and 8 controls (Group 2). Group 1 patients had no clinically-evident retinal toxicity. All subjects underwent SDOCT imaging of the macula. An image segmentation technique was used to measure thickness of 6 retinal layers at 200 µm intervals. A mixed-effects model was used for multivariate analysis. Results By measuring total retinal thickness either at the central macular (2800 µm in diameter), the perifoveal region 1200-µm-width ring surrounding the central macula), or the overall macular area (5200 µm in diameter), there were no significant differences in the thickness between Groups 1 and 2. On an image segmentation analysis, selective thinning of the inner plexiform + ganglion cell layers (p=0.021) was observed only in the perifoveal area of the patients in Group 1 compared to that of Group 2 by using the mixed-effects model analysis. Conclusions Our results suggest that chronic exposure to hydroxychloroquine is associated with thinning of the perifoveal inner retinal layers, especially in the ganglion cell and inner plexiform layers, even in the absence of functional or structural clinical changes involving the photoreceptor or retinal pigment epithelial cell layers. This may be a contributing factor as the reason most patients who have early detectable signs of drug toxicity present with paracentral or pericentral scotomas. PMID:20395978

  8. Focal retinal phlebitis.

    Science.gov (United States)

    Hoang, Quan V; Freund, K Bailey; Klancnik, James M; Sorenson, John A; Cunningham, Emmett T; Yannuzzi, Lawrence A

    2012-01-01

    To report three cases of solitary, focal retinal phlebitis. An observational case series. Three eyes in three patients were noted to have unilateral decreased vision, macular edema, and a focal retinal phlebitis, which was not at an arteriovenous crossing. All three patients developed a branch retinal vein occlusion at the site of inflammation. These patients had no other evidence of intraocular inflammation, including vitritis, retinitis, retinal vasculitis, or choroiditis, nor was there any systemic disorder associated with inflammation, infection, or coagulation identified. Focal retinal phlebitis appears to be an uncommon and unique entity that produces macular edema and ultimately branch retinal vein occlusion. In our patients, the focal phlebitis and venous occlusion did not occur at an arteriovenous crossing, which is the typical site for branch retinal venous occlusive disease. This suggests that our cases represent a distinct clinical entity, which starts with a focal abnormality in the wall of a retinal venule, resulting in surrounding exudation and, ultimately, ends with branch retinal vein occlusion.

  9. Pressure vessels and methods of sealing leaky tubes disposed in pressure vessels

    International Nuclear Information System (INIS)

    Larson, G.C.

    1980-01-01

    This invention relates to pressure vessels and to methods of sealing leaky tubes in them and is especially applicable to pressure vessels in the form of sheet-and-tube type heat exchangers constructed with a large number of relatively small diameter tubes grouped in a bundle. To seal off a leaky tube in such a heat exchanger an explosive activated plug in the form of a hollow metal body is used, inserted at each end of the tube to be sealed. Using the arrangement of pressure vessel and associated tube sheets and the explosive activated plug method of sealing a leaky tube as described in this invention it is claimed that distortion of the adjacent tubes and the tube sheets is reduced when the explosive activated plugs are detonated. (U.K.)

  10. Bevacizumab treatment reduces retinal neovascularization in a mouse model of retinopathy of prematurity

    Institute of Scientific and Technical Information of China (English)

    Fei; Feng; Yan; Cheng; Qing-Huai; Liu

    2014-01-01

    ·AIM: To evaluate the effect of different bevacizumab concentrations on retinal neovascularization in a retinopathy of prematurity(ROP) mouse model.·METHODS: A total of 60 of C57BL/6 J mice were exposed to 75% ±2% oxygen from postnatal d7 to postnatal d12. Fifteen nonexposed mice served as negative controls(group A). On d12, 30 mice(group C)were injected with 2.5 μg intravitreal bevacizumab(IVB),30 mice(group D) were injected with 1.25 μg IVB in one eye. The contralateral eyes were injected with balanced salt solution(BSS)(control group =group B). The adenosine diphosphatase(ADPase) histochemical technique was used for retinal flat mount to assess the oxygen-induced changes of retinal vessels.Neovascularization was quantified by counting the endothelial cell proliferation on the vitreal side of the inner limiting membrane of the retina. Histological changes were examined by light microscopy. The mRNA levels of vascular endothelial growth factor(VEGF) were quantified by Real-time PCR. Western-blotting analysis was performed to examine the expression of P-VEGFR.· RESULTS: Comparing with the control group B,regular distributions and reduced tortuosity of vessels were observed in our retinal flat mounts in groups C and D. The endothelial cell count per histological section was lower in groups C(P <0.0001) and D(P <0.0001) compared with the control group B. Histological evaluation showed no retinal toxicity in any group. In all oxygen treated groups VEGF mRNA expression was significantly increased as compared to age-matched controls. No significant change in VEGF mRNA expression could be achieved in either of the treatments or the oxygen controls. The results of the Western blot were consistent with that of the Real-time PCR analysis.·CONCLUSION: An intravitreal injection of bevacizumab is able to reduce angioproliferative retinopathy in a mouse model for oxygen-induced retinopathy.

  11. Why choroid vessels appear dark in clinical OCT images

    Science.gov (United States)

    Kirby, Mitchell A.; Li, Chenxi; Choi, Woo June; Gregori, Giovanni; Rosenfeld, Philip; Wang, Ruikang

    2018-02-01

    With the onset of clinically available spectral domain (SD-OCT) and swept source (SS-OCT) systems, clinicians are now easily able to recognize sub retinal microstructure and vascularization in the choroidal and scleral regions. As the bloodrich choroid supplies nutrients to the upper retinal layers, the ability to monitor choroid function accurately is of vital importance for clinical assessment of retinal health. However, the physical appearance of the choroid blood vessels (darker under a healthy Retinal Pigmented Epithelium (RPE) compared to regions displaying an RPE atrophic lesion) has led to confusion within the OCT ophthalmic community. The differences in appearance between each region in the OCT image may be interpreted as different vascular patterns when the vascular networks are in fact very similar. To explain this circumstance, we simulate light scattering phenomena in the RPE and Choroid complexes using the finite difference time domain (FDTD) method. The simulation results are then used to describe and validate imaging features in a controlled multi-layered tissue phantom designed to replicate human RPE, choroid, and whole blood microstructure. Essentially, the results indicate that the strength of the OCT signal from choroidal vasculature is dependent on the health and function of the RPE, and may not necessarily directly reflect the health and function of the choroidal vasculature.

  12. Ursodeoxycholic Acid Attenuates Endoplasmic Reticulum Stress-Related Retinal Pericyte Loss in Streptozotocin-Induced Diabetic Mice

    Directory of Open Access Journals (Sweden)

    Yoo-Ri Chung

    2017-01-01

    Full Text Available Loss of pericytes, an early hallmark of diabetic retinopathy (DR, results in breakdown of the blood-retinal barrier. Endoplasmic reticulum (ER stress may be involved in this process. The purpose of this study was to examine the effects of ursodeoxycholic acid (UDCA, a known ameliorator of ER stress, on pericyte loss in DR of streptozotocin- (STZ- induced diabetic mice. To assess the extent of DR, the integrity of retinal vessels and density of retinal capillaries in STZ-induced diabetic mice were evaluated. Additionally, induction of ER stress and the unfolded protein response (UPR were assessed in diabetic mice and human retinal pericytes exposed to advanced glycation end products (AGE or modified low-density lipoprotein (mLDL. Fluorescein dye leakage during angiography and retinal capillary density were improved in UDCA-treated diabetic mice, compared to the nontreated diabetic group. Among the UPR markers, those involved in the protein kinase-like ER kinase (PERK pathway were increased, while UDCA attenuated UPR in STZ-induced diabetic mice as well as AGE- or mLDL-exposed retinal pericytes in culture. Consequently, vascular integrity was improved and pericyte loss reduced in the retina of STZ-induced diabetic mice. Our findings suggest that UDCA might be effective in protecting against DR.

  13. In-vessel coolability and steam explosion in Nordic BWRs

    Energy Technology Data Exchange (ETDEWEB)

    Ma, W.; Li, L.; Hansson, R.; Villanueva, W.; Kudinov, P.; Manickam, L.; Tran, C.-T. (Royal Institute of Technology (KTH) (Sweden))

    2011-05-15

    The objective of this research is to reduce the uncertainty in quantification of steam explosion risk and in-vessel coolability in the Nordic BWR plants which employ cavity flooding as severe accident management (SAM) strategy. To quantify the coolability of debris bed packed with irregular particles, the friction laws of fluid flow in particulate beds packed with non-spherical particles were investigated on the POMECO-FL test facility, and the experimental data suggest that the Ergun equation is applicable if the effective particle diameter of the particles is represented by the equivalent diameter of the particles, which is the product of Sauter mean diameter and shape factor of the particles. One-way coupling analysis between PECM model for melt pool heat transfer and ANSYS thermo-structural mechanics was performed to analyze the vessel creep, and the results revealed two different modes of vessel failure: a 'ballooning' of the vessel bottom and a 'localized creep' concentrated within the vicinity of the top surface of the melt pool. Single-droplet steam explosion experiments were carried out by using oxidic mixture of WO{sub 3}-CaO, and the results show an apparent difference in steam explosion energetics between the eutectic and non-eutectic melts at low melt superheat (100 deg. C). (Author)

  14. In-vessel coolability and steam explosion in Nordic BWRs

    International Nuclear Information System (INIS)

    Ma, W.; Li, L.; Hansson, R.; Villanueva, W.; Kudinov, P.; Manickam, L.; Tran, C.-T.

    2011-05-01

    The objective of this research is to reduce the uncertainty in quantification of steam explosion risk and in-vessel coolability in the Nordic BWR plants which employ cavity flooding as severe accident management (SAM) strategy. To quantify the coolability of debris bed packed with irregular particles, the friction laws of fluid flow in particulate beds packed with non-spherical particles were investigated on the POMECO-FL test facility, and the experimental data suggest that the Ergun equation is applicable if the effective particle diameter of the particles is represented by the equivalent diameter of the particles, which is the product of Sauter mean diameter and shape factor of the particles. One-way coupling analysis between PECM model for melt pool heat transfer and ANSYS thermo-structural mechanics was performed to analyze the vessel creep, and the results revealed two different modes of vessel failure: a 'ballooning' of the vessel bottom and a 'localized creep' concentrated within the vicinity of the top surface of the melt pool. Single-droplet steam explosion experiments were carried out by using oxidic mixture of WO 3 -CaO, and the results show an apparent difference in steam explosion energetics between the eutectic and non-eutectic melts at low melt superheat (100 deg. C). (Author)

  15. Neutron Assay System for Confinement Vessel Disposition

    International Nuclear Information System (INIS)

    Frame, Katherine C.; Bourne, Mark M.; Crooks, William J.; Evans, Louise; Mayo, Douglas R.; Miko, David K.; Salazar, William R.; Stange, Sy; Valdez, Jose I.; Vigil, Georgiana M.

    2012-01-01

    Los Alamos National Laboratory has a number of spherical confinement vessels (CVs) remaining from tests involving nuclear materials. These vessels have an inner diameter of 6 feet with 1-inch thick steel walls. The goal of the Confinement Vessel Disposition (CVD) project is to remove debris and reduce contamination inside the CVs. The Confinement Vessel Assay System (CVAS) was developed to measure the amount of special nuclear material (SNM) in CVs before and after cleanout. Prior to cleanout, the system will be used to perform a verification measurement of each vessel. After cleanout, the system will be used to perform safeguards-quality assays of (le)100-g 239 Pu equivalent in a vessel for safeguards termination. The CVAS has been tested and calibrated in preparation for verification and safeguards measurements.

  16. Tlx acts as a proangiogenic switch by regulating extracellular assembly of fibronectin matrices in retinal astrocytes.

    Science.gov (United States)

    Uemura, Akiyoshi; Kusuhara, Sentaro; Wiegand, Stanley J; Yu, Ruth T; Nishikawa, Shin-ichi

    2006-02-01

    In response to hypoxia, hypoxia-inducible factors act as the primary proangiogenic triggers by regulating transcription levels of target genes, including VEGF. However, little is known about the specific factors that control other components of the angiogenic process, particularly formation of matrix scaffolds that promote adhesion and migration of endothelial cells. We show that in the postnatal mouse retina, the orphan nuclear receptor tailless (Tlx) is strongly expressed in the proangiogenic astrocytes, which secrete VEGF and fibronectin. Tlx expression by retinal astrocytes is controlled by oxygen concentration and rapidly downregulated upon contact with blood vessels. In mice null for Tlx, retinal astrocytes maintain VEGF expression; however, the extracellular assembly of fibronectin matrices by astrocytes is severely impaired, leading to defective scaffold formation and a complete failure of normal retinal vascular development. This work identifies Tlx as an essential component of the molecular network involved in the hypoxia-inducible proangiogenic switch in retinal astrocytes.

  17. Glaucoma Diagnostic Ability of the Optical Coherence Tomography Angiography Vessel Density Parameters.

    Science.gov (United States)

    Chung, Jae Keun; Hwang, Young Hoon; Wi, Jae Min; Kim, Mijin; Jung, Jong Jin

    2017-11-01

    To investigate the glaucoma diagnostic abilities of vessel density parameters as determined by optical coherence tomography (OCT) angiography in different stages of glaucoma. A total of 113 healthy eyes and 140 glaucomatous eyes were enrolled. Diagnostic abilities of the OCT vessel density parameters in the optic nerve head (ONH), peripapillary, and macular regions were evaluated by calculating the area under the receiver operation characteristic curves (AUCs). AUCs of the peripapillary vessel density parameters and circumpapillary retinal nerve fiber layer (RNFL) thickness were compared. OCT angiography vessel densities in the ONH, peripapillary, and macular regions in the glaucomatous eyes were significantly lower than those in the healthy eyes (P glaucoma detection. The peripapillary vessel density parameters showed similar AUCs with the corresponding sectoral RNFL thickness (P > 0.05). However, in the early stage of glaucoma, the AUCs of the inferotemporal and temporal peripapillary vessel densities were significantly lower than that of the RNFL thickness (P glaucoma diagnostic ability with circumpapillary RNFL thickness, in the early stage, the vessel density parameters showed limited clinical value.

  18. Retinal Vessel Calibers Predict Long-term Microvascular Complications in Type 1 Diabetes

    DEFF Research Database (Denmark)

    Broe, Rebecca; Rasmussen, Malin L; Frydkjaer-Olsen, Ulrik

    2014-01-01

    Diabetic neuropathy, nephropathy, and retinopathy cause significant morbidity in patients with type 1 diabetes, even though improvements in treatment modalities delay the appearance and reduce the severity of these complications. To prevent or further delay the onset, it is necessary to better.......5-1 disc diameter from the disc margin were measured and summarized as the central artery and vein equivalents. In multiple regression analyses, we found wider venular diameters and smaller arteriolar diameters were both predictive of the 16-year development of nephropathy, neuropathy, and proliferative...

  19. Microscope-Integrated Optical Coherence Tomography Angiography in the Operating Room in Young Children With Retinal Vascular Disease.

    Science.gov (United States)

    Chen, Xi; Viehland, Christian; Carrasco-Zevallos, Oscar M; Keller, Brenton; Vajzovic, Lejla; Izatt, Joseph A; Toth, Cynthia A

    2017-05-01

    Intraoperative optical coherence tomography (OCT) has gained traction as an important adjunct for clinical decision making during vitreoretinal surgery, and OCT angiography (OCTA) has provided novel insights in clinical evaluation of retinal diseases. To date, these two technologies have not been applied in combination to evaluate retinal vascular disease in the operating suite. To conduct microscope-integrated, swept-source OCTA (MIOCTA) in children with retinal vascular disease. In this case report analysis, OCT imaging in pediatric patients, MIOCTA images were obtained during examination under anesthesia from a young boy with a history of idiopathic vitreous hemorrhage and a female infant with familial exudative vitreoretinopathy. Side-by-side comparison of research MIOCT angiograms and clinically indicated fluorescein angiograms. In 2 young children with retinal vascular disease, the MIOCTA images showed more detailed vascular patterns than were visible on the fluorescein angiograms although within a more posterior field of view. The MIOCTA system allowed visualization of small pathological retinal vessels in the retinal periphery that were obscured in the fluorescein angiograms by fluorescein staining from underlying, preexisting laser scars. This is the first report to date of the use of MIOCTA in the operating room for young children with retinal vascular disease. Further optimization of this system may allow noninvasive detailed evaluation of retinal vasculature during surgical procedures and in patients who could not cooperate with in-office examinations.

  20. Analysis of nuclear reactor pressure vessel flanges

    International Nuclear Information System (INIS)

    Oliveira, C.A.N. de; Augusto, O.B.

    1985-01-01

    This work proposes a methodology for the structural analysis of high diameter nuclear reactor pressure vessel flanges. In the analysis the vessel is divided into shell-of-revolution elements, the flanges are represented by rigid rings, and the bolts are treated as beams. The flexibility method is used for solving the problem, and the results are compared with results obtained by the finite element method. (Author) [pt

  1. Retinal thinning after internal limiting membrane peeling for idiopathic macular hole.

    Science.gov (United States)

    Imamura, Yutaka; Ishida, Masahiro

    2018-03-01

    To determine the changes in retinal thickness and whether they correlate with the size of the macular hole (MH) after vitrectomy with internal limiting membrane peeling. Retrospective, interventional case series METHODS: Consecutive patients with an MH and undergoing pars plana vitrectomy with internal limiting membrane peeling were studied. The retinal thicknesses in the inner 4 sectors as defined by the Early Treatment of Diabetic Retinopathy Study were measured using spectral-domain optical coherence tomography (SD-OCT) before and at 2 weeks and 1, 3, 6, and 12 months after the surgery. The basal and minimum diameters of the MHs were measured. The correlations between the retinal thicknesses and the size of the MH were determined. Thirty-three eyes of 32 consecutive patients (18 women; mean age, 64.2 ± 8.8 years) with an MH were studied. Thirteen eyes had a stage-2 MH; 12 eyes, a stage-3 MH; and 8 eyes, a stage-4 MH. The mean retinal thickness in the temporal sector was 362.8 ± 29.9 µm preoperatively, 337.9 ± 20.6 µm at 2 weeks postoperatively, and 307.6 ± 20.2 µm at 12 months postoperatively (P peeling.

  2. Dorzolamide increases retinal oxygen tension after branch retinal vein occlusion

    DEFF Research Database (Denmark)

    Noergaard, Michael Hove; Bach-Holm, Daniella; Scherfig, Erik

    2008-01-01

    To study the effect of dorzolamide on the preretinal oxygen tension (RPO(2)) in retinal areas affected by experimental branch retinal vein occlusion (BRVO) in pigs.......To study the effect of dorzolamide on the preretinal oxygen tension (RPO(2)) in retinal areas affected by experimental branch retinal vein occlusion (BRVO) in pigs....

  3. Retinal Oxygen Delivery and Metabolism in Healthy and Sickle Cell Retinopathy Subjects.

    Science.gov (United States)

    Shahidi, Mahnaz; Felder, Anthony E; Tan, Ou; Blair, Norman P; Huang, David

    2018-04-01

    Reduction in inner retinal oxygen delivery (DO2) can cause retinal hypoxia and impair inner retinal oxygen metabolism (MO2), leading to vision loss. The purpose of the current study was to establish measurements of DO2 and MO2 in healthy subjects and test the hypothesis that DO2 and MO2 are reduced in sickle cell retinopathy (SCR) subjects. Dual wavelength retinal oximetry and Doppler optical coherence tomography were performed in 12 healthy control and 12 SCR subjects. Images were analyzed to measure retinal arterial and venous oxygen content (O2A and O2V), venous diameter (DV), and total retinal blood flow (TRBF). Retinal arteriovenous oxygen content difference (O2AV), DO2, MO2, and oxygen extraction fraction (OEF) were calculated according to the following equations: O2AV = O2A - O2V; DO2 = TRBF * O2A; MO2 = TRBF * O2AV; OEF = MO2/DO2. Retinal DV and TRBF were higher in the SCR group as compared to the control group, whereas, O2A, O2V, and O2AV were lower in SCR group as compared to the control group. DO2, MO2, and OEF were not significantly different between control and SCR groups. MO2 and DO2 were linearly related, such that higher MO2 was associated with higher DO2. There was an inverse relationship between TRBF and OEF, such that lower TRBF was associated with higher OEF. Increased blood flow compensated for decreased oxygen content, thereby maintaining DO2, MO2, and OEF at predominately lower stages of SCR. Quantitative assessment of these parameters has the potential to advance knowledge and improve diagnostic evaluation of retinal ischemic conditions.

  4. Peripheral retinal degenerations and the risk of retinal detachment.

    Science.gov (United States)

    Lewis, Hilel

    2003-07-01

    To review the degenerative diseases of the peripheral retina in relationship with the risk to develop a rhegmatogenous retinal detachment and to present recommendations for use in eyes at increased risk of developing a retinal detachment. Focused literature review and author's clinical experience. Retinal degenerations are common lesions involving the peripheral retina, and most of them are clinically insignificant. Lattice degeneration, degenerative retinoschisis, cystic retinal tufts, and, rarely, zonular traction tufts, can result in a rhegmatogenous retinal detachment. Therefore, these lesions have been considered for prophylactic therapy; however, adequate studies have not been performed to date. Well-designed, prospective, randomized clinical studies are necessary to determine the benefit-risk ratio of prophylactic treatment. In the meantime, the evidence available suggests that most of the peripheral retinal degenerations should not be treated except in rare, high-risk situations.

  5. The anti-ALS drug riluzole attenuates pericyte loss in the diabetic retinopathy of streptozotocin-treated mice

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jeong A. [Neural Injury Research Center, Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul (Korea, Republic of); Chung, Yoo-Ri [Department of Ophthalmology, University of Ulsan College of Medicine, Seoul (Korea, Republic of); Byun, Hyae-Ran [Neural Injury Research Center, Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul (Korea, Republic of); Park, Hwangseo [Department of Bioscience and Biotechnology, Sejong University, Seoul (Korea, Republic of); Koh, Jae-Young, E-mail: jkko@amc.seoul.kr [Neural Injury Research Center, Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul (Korea, Republic of); Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of); Yoon, Young Hee, E-mail: yhyoon@amc.seoul.kr [Department of Ophthalmology, University of Ulsan College of Medicine, Seoul (Korea, Republic of)

    2017-01-15

    Loss of pericytes, considered an early hallmark of diabetic retinopathy, is thought to involve abnormal activation of protein kinase C (PKC). We previously showed that the anti-amyotrophic lateral sclerosis (ALS) drug riluzole functions as a PKC inhibitor. Here, we examined the effects of riluzole on pathological changes in diabetic retinopathy. Pathological endpoints examined in vivo included the number of pericytes and integrity of retinal vessels in streptozotocin (STZ)-induced diabetic mice. In addition, PKC activation and the induction of monocyte chemotactic protein (MCP1) were assessed in diabetic mice and in human retinal pericytes exposed to advanced glycation end product (AGE) or modified low-density lipoprotein (mLDL). The diameter of retinal vessels and the number of pericytes were severely reduced, and the levels of MCP1 and PKC were increased in STZ-induced diabetic mice. Administration of riluzole reversed all of these changes. Furthermore, the increased expression of MCP1 in AGE- or mLDL-treated cultured retinal pericytes was inhibited by treatment with riluzole or the PKC inhibitor GF109203X. In silico modeling showed that riluzole fits well within the catalytic pocket of PKC. Taken together, our results demonstrate that riluzole attenuates both MCP1 induction and pericyte loss in diabetic retinopathy, likely through its direct inhibitory effect on PKC. - Highlights: • The effects of riluzole were examined in streptozotocin-induced diabetic mice. • The diameter of retinal vessels and the number of pericytes were severely reduced. • The levels of MCP1 and PKC were increased, while riluzole reversed all changes. • Riluzole attenuated the level of MCP1 in AGE- or mLDL-treated retinal pericytes. • Riluzole attenuated both MCP1 induction and pericyte loss in diabetic retinopathy.

  6. The anti-ALS drug riluzole attenuates pericyte loss in the diabetic retinopathy of streptozotocin-treated mice

    International Nuclear Information System (INIS)

    Choi, Jeong A.; Chung, Yoo-Ri; Byun, Hyae-Ran; Park, Hwangseo; Koh, Jae-Young; Yoon, Young Hee

    2017-01-01

    Loss of pericytes, considered an early hallmark of diabetic retinopathy, is thought to involve abnormal activation of protein kinase C (PKC). We previously showed that the anti-amyotrophic lateral sclerosis (ALS) drug riluzole functions as a PKC inhibitor. Here, we examined the effects of riluzole on pathological changes in diabetic retinopathy. Pathological endpoints examined in vivo included the number of pericytes and integrity of retinal vessels in streptozotocin (STZ)-induced diabetic mice. In addition, PKC activation and the induction of monocyte chemotactic protein (MCP1) were assessed in diabetic mice and in human retinal pericytes exposed to advanced glycation end product (AGE) or modified low-density lipoprotein (mLDL). The diameter of retinal vessels and the number of pericytes were severely reduced, and the levels of MCP1 and PKC were increased in STZ-induced diabetic mice. Administration of riluzole reversed all of these changes. Furthermore, the increased expression of MCP1 in AGE- or mLDL-treated cultured retinal pericytes was inhibited by treatment with riluzole or the PKC inhibitor GF109203X. In silico modeling showed that riluzole fits well within the catalytic pocket of PKC. Taken together, our results demonstrate that riluzole attenuates both MCP1 induction and pericyte loss in diabetic retinopathy, likely through its direct inhibitory effect on PKC. - Highlights: • The effects of riluzole were examined in streptozotocin-induced diabetic mice. • The diameter of retinal vessels and the number of pericytes were severely reduced. • The levels of MCP1 and PKC were increased, while riluzole reversed all changes. • Riluzole attenuated the level of MCP1 in AGE- or mLDL-treated retinal pericytes. • Riluzole attenuated both MCP1 induction and pericyte loss in diabetic retinopathy.

  7. Repair of Total Tractional Retinal Detachment in Norrie Disease: Report of Technique and Successful Surgical Outcome.

    Science.gov (United States)

    Todorich, Bozho; Thanos, Aristomenis; Yonekawa, Yoshihiro; Capone, Antonio

    2017-03-01

    Norrie disease is a rare, but devastating cause of pediatric retinal detachment, universally portending a poor visual prognosis. This paper describes successful surgical management of an infant with total retinal detachment associated with Norrie disease mutation. The infant was a full-term white male who presented with bilateral total funnel retinal detachments (RDs). He underwent genetic testing, which demonstrated single-point mutation 133 G>A transition in exon 2 of the NDP gene. The retinal detachment was managed with translimbal iridectomy, lensectomy, capsulectomy, and vitrectomy. Careful dissection of the retrolental membranes resulted in opening of the funnel. Single-stage surgery in this child's eye achieved re-attachment of the posterior pole with progressive reabsorption of subretinal fluid and cholesterol without the need for external drainage. Fluorescein angiography, performed at 2 months postoperatively, demonstrated perfusion of major vascular arcades, but with significant abnormalities and aneurysmal changes of higher-order vessels, suggestive of retinal and vascular dysplasia. The child has maintained brisk light perception vision. Early surgical intervention with careful dissection of tractional tissues can potentially result in good anatomic outcomes in some patients with Norrie disease-associated retinal detachment. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:260-262.]. Copyright 2017, SLACK Incorporated.

  8. Measuring the diameter of rising gas bubbles by means of the ultrasound transit time technique

    Energy Technology Data Exchange (ETDEWEB)

    Richter, T., E-mail: Thomas.Richter6@tu-dresden.de; Eckert, K., E-mail: Kerstin.Eckert@tu-dresden.de; Yang, X.; Odenbach, S.

    2015-09-15

    Highlights: • Ultrasound transit time technique (UTTT) is applied to the zig-zag raise of gas bubble. • Comparison of bubble diameter and tilt, measured by UTTT, with high-speed imaging. • Uncertainty in the determination of the bubble diameter by UTTT is less than 7%. • UTTT is able to measure dynamic changes in bubble size in opaque liquids and vessels. • UTTT can be applied to liquid metal loops. - Abstract: This study presents ultrasound transit time technique (UTTT) measurements of the diameter variations of single argon bubbles rising in a zig-zag trajectory in water. Simultaneous size measurements with a high-speed camera show that UTTT resolves both the apparent diameter and the tilt of the bubble axis with an accuracy of better than 7%. This qualifies UTTT for the measurement of bubble sizes in opaque liquids, such as liquid metals, or vessels.

  9. Retinal vascular oximetry during ranibizumab treatment of central retinal vein occlusion

    DEFF Research Database (Denmark)

    Traustason, Sindri; la Cour, Morten; Larsen, Michael

    2014-01-01

    PURPOSE: To investigate the effect of intravitreal injections of the vascular endothelial growth factor inhibitor ranibizumab on retinal oxygenation in patients with central retinal vein occlusion (CRVO). METHODS: Retinal oxygen saturation in patients with CRVO was analysed using the Oxymap Retin...

  10. Witnessing the first sign of retinitis pigmentosa onset in the allegedly normal eye of a case of unilateral RP: a 30-year follow-up.

    Science.gov (United States)

    Gauvin, Mathieu; Chakor, Hadi; Koenekoop, Robert K; Little, John M; Lina, Jean-Marc; Lachapelle, Pierre

    2016-06-01

    A patient initially presented with constricted visual field, attenuated retinal vasculature, pigmentary clumping and reduced ERG in OS only, suggestive of unilateral retinitis pigmentosa (RP). This patient was subsequently seen on eight occasions (over three decades), and, with time, the initially normal eye (OD) gradually showed signs of RP-like degeneration. The purpose of this study was to evaluate which clinical modality (visual field, funduscopy or electroretinography) could have first predicted this fate. At each time points, data obtained from our patient were compared to normative data using Z tests. At initial visit, all tests were significantly (p retinal vessel diameter in OD reduced gradually to reach statistical significance at the 5th visit and 6th visit (21 and 22 years after the first examination, respectively). In OD, the amplitude of the scotopic and photopic ERGs reduced gradually and was significantly smaller than normal at the 2nd visit (after 11 years) and 3rd visit (after 18 years), respectively. When the photopic ERG was analyzed using the discrete wavelet transform (DWT), we were able to detect a significant change at the 2nd visit (after 11 years) instead of the 3rd visit (18 years). Our study allowed us to witness the earliest manifestation of an RP disease process. The ERG was the first test to detect significant RP changes. A significantly earlier detection of ERG anomalies was obtained when the DWT was used, demonstrating its advantage for early detection of ERG changes.

  11. Retinal oxygen extraction in individuals with type 1 diabetes with no or mild diabetic retinopathy.

    Science.gov (United States)

    Fondi, Klemens; Wozniak, Piotr A; Howorka, Kinga; Bata, Ahmed M; Aschinger, Gerold C; Popa-Cherecheanu, Alina; Witkowska, Katarzyna J; Hommer, Anton; Schmidl, Doreen; Werkmeister, René M; Garhöfer, Gerhard; Schmetterer, Leopold

    2017-08-01

    The aim of this study was to compare retinal oxygen extraction in individuals with diabetes with no or mild non-proliferative diabetic retinopathy and healthy age- and sex-matched volunteers. A total of 24 participants with type 1 diabetes and 24 healthy age- and sex-matched volunteers were included in this cross-sectional study. Retinal oxygen extraction was measured by combining total retinal blood flow measurements using a custom-built bi-directional Doppler optical coherence tomography system with measurements of oxygen saturation using spectroscopic reflectometry. Based on previously published mathematical modelling, the oxygen content in retinal vessels and total retinal oxygen extraction were calculated. Total retinal blood flow was higher in diabetic participants (46.4 ± 7.4 μl/min) than in healthy volunteers (40.4 ± 5.3 μl/min, p = 0.002 between groups). Oxygen content in retinal arteries was comparable between the two groups, but oxygen content in retinal veins was higher in participants with diabetes (0.15 ± 0.02 ml O 2 /ml) compared with healthy control participants (0.13 ± 0.02 ml O 2 /ml, p diabetes compared with healthy volunteers (total retinal oxygen extraction 1.40 ± 0.44 vs 1.70 ± 0.47 μl O 2 /min, respectively, p = 0.03). Our data indicate early retinal hypoxia in individuals with type 1 diabetes with no or mild diabetic retinopathy as compared with healthy control individuals. Further studies are required to fully understand the potential of the technique in risk stratification and treatment monitoring. ClinicalTrials.gov NCT01843114.

  12. Ruptured Retinal Arterial Macroaneurysm Secondary to Toxoplasmic Kyrieleis Arteriolitis: A Case Report

    Directory of Open Access Journals (Sweden)

    Natalie Huang

    2017-07-01

    Full Text Available Purpose: The aim of this report was to describe multimodal ocular imaging findings in a patient who presented with a ruptured retinal arterial macroaneurysm (RAM associated with toxoplasmic Kyrieleis arteriolitis. Methods: We report the case of a 64-year-old man with a history of systemic hypertension and dense amblyopia of the left eye who presented with decreased vision and new floaters in the left eye. Color fundus photography, spectral-domain optical coherence tomography, fluorescein angiography, and indocyanine green angiography were used as diagnostic imaging tools. Results: No signs of hypertensive retinopathy were noted in the right eye. Multiple chorioretinal scars characteristic of previous toxoplasmosis were revealed in the left eye, with one covering most of the macula. Periarterial plaques or Kyrieleis arteriolitis were observed in retinal arteries surrounding the toxoplasmic retinal scars. Multiple RAMs were observed in these vessels, one of which was acutely ruptured. A perivenular plaque associated with a chronic branch retinal vein occlusion (BRVO was noted along the same arcade at the arteriovenous crossing. Conclusion: RAM formation and BRVO can present as possible long-term complications of toxoplasmic Kyrieleis arteriolitis. This is the first reported case demonstrating an association between toxoplasmic Kyrieleis arteriolitis and RAM formation.

  13. Retinal Thickening and Photoreceptor Loss in HIV Eyes without Retinitis.

    Directory of Open Access Journals (Sweden)

    Cheryl A Arcinue

    Full Text Available To determine the presence of structural changes in HIV retinae (i.e., photoreceptor density and retinal thickness in the macula compared with age-matched HIV-negative controls.Cohort of patients with known HIV under CART (combination Antiretroviral Therapy treatment were examined with a flood-illuminated retinal AO camera to assess the cone photoreceptor mosaic and spectral-domain optical coherence tomography (SD-OCT to assess retinal layers and retinal thickness.Twenty-four eyes of 12 patients (n = 6 HIV-positive and 6 HIV-negative were imaged with the adaptive optics camera. In each of the regions of interest studied (nasal, temporal, superior, inferior, the HIV group had significantly less mean cone photoreceptor density compared with age-matched controls (difference range, 4,308-6,872 cones/mm2. A different subset of forty eyes of 20 patients (n = 10 HIV-positive and 10 HIV-negative was included in the retinal thickness measurements and retinal layer segmentation with the SD-OCT. We observed significant thickening in HIV positive eyes in the total retinal thickness at the foveal center, and in each of the three horizontal B-scans (through the macular center, superior, and inferior to the fovea. We also noted that the inner retina (combined thickness from ILM through RNFL to GCL layer was also significantly thickened in all the different locations scanned compared with HIV-negative controls.Our present study shows that the cone photoreceptor density is significantly reduced in HIV retinae compared with age-matched controls. HIV retinae also have increased macular retinal thickness that may be caused by inner retinal edema secondary to retinovascular disease in HIV. The interaction of photoreceptors with the aging RPE, as well as possible low-grade ocular inflammation causing diffuse inner retinal edema, may be the key to the progressive vision changes in HIV-positive patients without overt retinitis.

  14. Tumor Blood Vessel Dynamics

    Science.gov (United States)

    Munn, Lance

    2009-11-01

    ``Normalization'' of tumor blood vessels has shown promise to improve the efficacy of chemotherapeutics. In theory, anti-angiogenic drugs targeting endothelial VEGF signaling can improve vessel network structure and function, enhancing the transport of subsequent cytotoxic drugs to cancer cells. In practice, the effects are unpredictable, with varying levels of success. The predominant effects of anti-VEGF therapies are decreased vessel leakiness (hydraulic conductivity), decreased vessel diameters and pruning of the immature vessel network. It is thought that each of these can influence perfusion of the vessel network, inducing flow in regions that were previously sluggish or stagnant. Unfortunately, when anti-VEGF therapies affect vessel structure and function, the changes are dynamic and overlapping in time, and it has been difficult to identify a consistent and predictable normalization ``window'' during which perfusion and subsequent drug delivery is optimal. This is largely due to the non-linearity in the system, and the inability to distinguish the effects of decreased vessel leakiness from those due to network structural changes in clinical trials or animal studies. We have developed a mathematical model to calculate blood flow in complex tumor networks imaged by two-photon microscopy. The model incorporates the necessary and sufficient components for addressing the problem of normalization of tumor vasculature: i) lattice-Boltzmann calculations of the full flow field within the vasculature and within the tissue, ii) diffusion and convection of soluble species such as oxygen or drugs within vessels and the tissue domain, iii) distinct and spatially-resolved vessel hydraulic conductivities and permeabilities for each species, iv) erythrocyte particles advecting in the flow and delivering oxygen with real oxygen release kinetics, v) shear stress-mediated vascular remodeling. This model, guided by multi-parameter intravital imaging of tumor vessel structure

  15. Evaluation of the normal thoracic and abdominal aorta diameters by computerized tomography

    International Nuclear Information System (INIS)

    Lucarelli, Claudio Luiz

    1995-01-01

    The study was undertaken to evaluate, through computerized tomography, the diameters of the normal thoracic and abdominal aorta, as well as they are connected to gender, age and body surface area; and the ratio between measurements obtained at the ascending and descending limbs of the thoracic aorta, and between the abdominal aortic diameters. For that reason, we measured the widest anteroposterior diameters of the thoracic aortas at the levels of the arch, the root, the pulmonary artery, and the thoracic-abdominal transition, as well as the level of the emergence of the superior mesenteric artery, of the renal hila and just cephalad to the bifurcation of the abdominal aortas of 350 patients without cardiovascular diseases who had undergone computerized tomography of the thorax and/or abdomen for any other reasons. Observation and statistic analyses led us to conclude that: 1) both the thoracic and abdominal aortic diameters are reduced from their proximal to their distal portions; 2) the body surface influences the size of the aorta, although only extreme variations alter the vessel's caliber; 3) vessel diameter was observed to gradually increase with age; 4) men were found to have larger diameters than age matched women; 5) the ratio between the ascending and descending aortic diameters varies according to gender and age; 6) the relations between abdominal aortic diameters measured at the level of renal hila and cephalad to the bifurcation are independent from gender and age. But the relation between those measured at the level of the superior mesenteric artery and cephalad to the bifurcation are linked to gender, but not to age. (author)

  16. Problems in manufacturing and transport of pressure vessels of integral reactors

    International Nuclear Information System (INIS)

    Kralovec, J.

    1997-01-01

    Integral water-cooled reactors are typical with eliminating large-diameter primary pipes and placing primary components, i.e. steam generators and pressurizers in reactor vessels. This arrangement leads to reactor pressure vessels of large dimensions: diameters, heights and thick walls and subsequently to great weights. Thus, even medium power units have pressure vessels which are on the very limit of present manufacturing capabilities. Principal manufacturing and inspection operations as well as pertinent equipment are concerned: welding, cladding, heat treatment, machining, shop-handling, non-destructive testing, hydraulic pressure tests etc. Tile transport of such a large and heavy component makes a problem which effects its design as well as the selection of the plant site. Railway, road and ship are possible ways of transport each of them having its advantages and limitations. Specific features and limits of the manufacture and transport of large pressure vessels are discussed in the paper. (author)

  17. Estimating retinal vascular permeability using the adiabatic approximation to the tissue homogeneity model with fluorescein videoangiography

    Science.gov (United States)

    Tichauer, Kenneth M.; Osswald, Christian R.; Dosmar, Emily; Guthrie, Micah J.; Hones, Logan; Sinha, Lagnojita; Xu, Xiaochun; Mieler, William F.; St. Lawrence, Keith; Kang-Mieler, Jennifer J.

    2015-06-01

    Clinical symptoms of diabetic retinopathy are not detectable until damage to the retina reaches an irreversible stage, at least by today's treatment standards. As a result, there is a push to develop new, "sub-clinical" methods of predicting the onset of diabetic retinopathy before the onset of irreversible damage. With diabetic retinopathy being associated with the accumulation of long-term mild damage to the retinal vasculature, retinal blood vessel permeability has been proposed as a key parameter for detecting preclinical stages of retinopathy. In this study, a kinetic modeling approach used to quantify vascular permeability in dynamic contrast-enhanced medical imaging was evaluated in noise simulations and then applied to retinal videoangiography data in a diabetic rat for the first time to determine the potential for this approach to be employed clinically as an early indicator of diabetic retinopathy. Experimental levels of noise were found to introduce errors of less than 15% in estimates of blood flow and extraction fraction (a marker of vascular permeability), and fitting of rat retinal fluorescein angiography data provided stable maps of both parameters.

  18. Nondamaging Retinal Laser Therapy: Rationale and Applications to the Macula.

    Science.gov (United States)

    Lavinsky, Daniel; Wang, Jenny; Huie, Philip; Dalal, Roopa; Lee, Seung Jun; Lee, Dae Yeong; Palanker, Daniel

    2016-05-01

    Retinal photocoagulation and nondamaging laser therapy are used for treatment of macular disorders, without understanding of the response mechanism and with no rationale for dosimetry. To establish a proper titration algorithm, we measured the range of tissue response and damage threshold. We then evaluated safety and efficacy of nondamaging retinal therapy (NRT) based on this algorithm for chronic central serous chorioretinopathy (CSCR) and macular telangiectasia (MacTel). Retinal response to laser treatment below damage threshold was assessed in pigmented rabbits by expression of the heat shock protein HSP70 and glial fibrillary acidic protein (GFAP). Energy was adjusted relative to visible titration using the Endpoint Management (EpM) algorithm. In clinical studies, 21 eyes with CSCR and 10 eyes with MacTel were treated at 30% EpM energy with high spot density (0.25-diameter spacing). Visual acuity, retinal and choroidal thickness, and subretinal fluid were monitored for 1 year. At 25% EpM energy and higher, HSP70 was expressed acutely in RPE, and GFAP upregulation in Müller cells was observed at 1 month. Damage appeared starting at 40% setting. Subretinal fluid resolved completely in 81% and partially in 19% of the CSCR patients, and visual acuity improved by 12 ± 3 letters. Lacunae in the majority of MacTel patients decreased while preserving the retinal thickness, and vision improved by 10 letters. Heat shock protein expression in response to hyperthermia helps define the therapeutic window for NRT. Lack of tissue damage enables high-density treatment to boost clinical efficacy, therapy in the fovea, and retreatments to manage chronic diseases.

  19. The Effects of Smoking on Anterior Segment Parameters, Retinal Nerve Fiber Layer, and Pupillary Functions

    Directory of Open Access Journals (Sweden)

    Bengü Ekinci Köktekir

    2014-01-01

    Full Text Available Objectives: To evaluate the alterations in the anterior segment parameters, retinal nerve fiber layer, and pupillary functions in smokers. Materials and Methods: In this case-control study, 45 eyes of 45 smokers and 45 eyes of 45 non-smoker control subjects were evaluated. All patients underwent measurement of anterior segment parameters with optical low coherence reflectometry (OLCR, mesopic and photopic pupillary diameter with an aberrometer device, retinal nerve fiber layer thickness with optical coherence tomography, and dry-eye assessment with Schirmer’s test. The results were compared with independent t-test by SPSS 16.0 Inc., and a p-value lower than 0.05 was determined as significant. Results: There was a significant difference between both groups in terms of mesopic pupil diameters that were measured with both OLCR and aberrometer device (p=0.03 and 0.02, respectively. Schirmer scores were also significantly decreased in smokers (p=0.001. The other measured parameters demonstrated no difference between smokers and non-smokers (p>0.05 for all. Conclusion: Smoking may affect pupillary functions, especially the mesopic pupillary diameter, and may cause a deficiency in pupil response under dark circumstances. (Turk J Ophthalmol 2014; 44: 11-4

  20. Phenomenological vessel burst investigations

    International Nuclear Information System (INIS)

    Hippelein, K.W.; Julisch, P.; Muz, J.; Schiedermaier, J.

    1985-07-01

    Fourteen burst experiments have been carried out using vessels with circumferential and longitudinal flaws, for investigation of the fracture behaviour, i.e. the time-related fracture opening. The vessels had dimensions (outer diameter x wall thickness = 800 x 47 mm) which correspond to the dimensions of the main coolant piping of a 1300 MW e PWR. The test specimens had been made of the base-safe material 20 MnMoNi 55 and of a special, 22 NiMoCr 37 base alloy. The experimental conditions with regard to pressure and temperature have been chosen so as to correspond to normal operating conditions of a PWR (p∝17.5 MPa, T∝300 0 C), i.e. the flaws have been so dimensioned that failure was to be expected at a pressure of p∝17.5 MPa. As a rule, water has been used as the pressure medium, or in some cases air, in order to influence the time-dependent pressure decrease. Fluid and structural dynamics calculations have also been made. In order to determine the impact of a fast propagating crack on the leak-to-fracture curve, which normally is defined by quasistationary experiments, suitable tests have been made with large-volume, cylindrical vessels (outer diameter x wall thickness x length = 3000 x 21 x 14000 mm) made of the material WSt E 43. The leak-before-fracture criterion has been confirmed. (orig./HP) [de

  1. Interventions for asymptomatic retinal breaks and lattice degeneration for preventing retinal detachment.

    Science.gov (United States)

    Wilkinson, Charles P

    2014-09-05

    Asymptomatic retinal breaks and lattice degeneration are visible lesions that are risk factors for later retinal detachment. Retinal detachments occur when fluid in the vitreous cavity passes through tears or holes in the retina and separates the retina from the underlying retinal pigment epithelium. Creation of an adhesion surrounding retinal breaks and lattice degeneration, with laser photocoagulation or cryotherapy, has been recommended as an effective means of preventing retinal detachment. This therapy is of value in the management of retinal tears associated with the symptoms of flashes and floaters and persistent vitreous traction upon the retina in the region of the retinal break, because such symptomatic retinal tears are associated with a high rate of progression to retinal detachment. Retinal tears and holes unassociated with acute symptoms and lattice degeneration are significantly less likely to be the sites of retinal breaks that are responsible for later retinal detachment. Nevertheless, treatment of these lesions frequently is recommended, in spite of the fact that the effectiveness of this therapy is unproven. The objective of this review was to assess the effectiveness and safety of techniques used to treat asymptomatic retinal breaks and lattice degeneration for the prevention of retinal detachment. We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2014, Issue 2), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to February 2014), EMBASE (January 1980 to February 2014), PubMed (January 1948 to February 2014), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials

  2. Treatment of Retinal Separation in HIV-infected Patients with Cytomegalovirus Retinitis

    Directory of Open Access Journals (Sweden)

    A. L. Onischenko

    2017-01-01

    Full Text Available HIV infection — is a socially significant problem for many countries, as the infected die in an average of 10-11 years due to the immunodeficiency virus. Up to 20% of patients with AIDS lose their sight because of cytomegalovirus retinitis (CMV retinitis, which occurs in 70% of HIV-infected people. In some patients with HIV infection blindness occurs because of acute retinal necrosis of CMV etiology. The algorithm of CMV retinitis treatment in HIV-infected patients is described in modern manuals (ganciclovir, valganciclovir, foscarnet and others on the background of antiretroviral therapy, but the tactics of treatment of retinal separation in these patients is not clearly defined. It may be “wait and see”, providing conservative treatment with antiviral drugs, and the active tactics — vitreoretinal surgery. In this article the authors present their personal clinical observations of three HIV-infected patients with CMV retinitis at the age of 8 to 36 years with a detailed analysis of the clinical data and the results of the laboratory tests. In particular, the authors give their own results of intravitreal introduction of ganciclovir in patients with CMV retinitis. Given the poor prognosis for the life of these patients, the authors put a deontological question of justification of active treatment of retinal separation in AIDS patients with CMV retinitis.

  3. Reducing catheter-related thrombosis using a risk reduction tool centered on catheter to vessel ratio.

    Science.gov (United States)

    Spencer, Timothy R; Mahoney, Keegan J

    2017-11-01

    In vascular access practices, the internal vessel size is considered important, and a catheter to vessel ratio (CVR) is recommended to assist clinicians in selecting the most appropriate-sized device for the vessel. In 2016, new practice recommendations stated that the CVR can increase from 33 to 45% of the vessels diameter. There has been evidence on larger diameter catheters and increased thrombosis risk in recent literature, while insufficient information established on what relationship to vessel size is appropriate for any intra-vascular device. Earlier references to clinical standards and guidelines did not clearly address vessel size in relation to the area consumed or external catheter diameter. The aim of this manuscript is to present catheter-related thrombosis evidence and develop a standardized process of ultrasound-guided vessel assessment, integrating CVR, Virchow's triad phenomenon and vessel health and preservation strategies, empowering an evidence-based approach to device placement. Through review, calculation and assessment on the areas of the 33 and 45% rule, a preliminary clinical tool was developed to assist clinicians make cognizant decisions when placing intravascular devices relating to target vessel size, focusing on potential reduction in catheter-related thrombosis. Increasing the understanding and utilization of CVRs will lead to a safer, more consistent approach to device placement, with potential thrombosis reduction strategies. The future of evidence-based data relies on the clinician to capture accurate vessel measurements and device-related outcomes. This will lead to a more dependable data pool, driving the relationship of catheter-related thrombosis and vascular assessment.

  4. Structural features and in-service inspection of the LTHR-200 pressure vessel

    International Nuclear Information System (INIS)

    Xiong Dunshi; He Shuyan; Liu Junjie; Yu Suyuan

    1993-01-01

    LTHR-200 is a low temperature district-heating reactor. It adopts double-shell design pressure vessel and metal containment. Because of the safety and structural features of the reactor, the in-service inspection of the pressure vessel can be simplified greatly. LTHR-200 is an integrated arrangement. Both its core components and the main heat exchangers are contained in the reactor pressure vessel. The coolant of the main loop is run by a full-power natural circulation and there need no main pumps and pipes. Thus, the reactor pressure vessel constitutes the pressure boundary of the reactor's main loop coolant. In regard to these features, a small-sized containment is designed for the reactor. The metal safety container with a small volume is placed closely around the reactor pressure vessel. Outside the metal containment, there is a large reinforced concrete construction for the reactor. Their main operation and design parameters are as follows: The pressure vessel: operation pressure = 2.4 MPa; design pressure = 3.0 MPa; design temperature = 250 deg C; 40 year fast neutron (E>1MeV) fluence in the belt-line region = < 10E16n/cm; internal diameter = 5000 mm; material SA516-70; shell thickness 65 mm; The metal containment: maximum operation pressure = 1.8 MPa; design pressure = 1.8 MPa; design temperature = 250 deg. C; upper internal diameter 7000 mm; lower internal diameter = 5600 mm; material = SA516-70; shell thickness, upper part = 80 mm; lower part = 50 mm. All penetrating pipes through the pressure vessel are located at the top penetration section of the shell. All the internal diameters of penetrating pipes are less than 50 mm. Inside and outside the metal containment wall respectively, isolating valves are connected to the reactor coolant pipe which passes through the containment. These two isolating valves use different driving methods. Every penetrating part of the reactor construction uses a proper form of structure according to safety requirements

  5. The Actin-Binding Protein α-Adducin Is Required for Maintaining Axon Diameter

    Directory of Open Access Journals (Sweden)

    Sérgio Carvalho Leite

    2016-04-01

    Full Text Available The actin-binding protein adducin was recently identified as a component of the neuronal subcortical cytoskeleton. Here, we analyzed mice lacking adducin to uncover the function of this protein in actin rings. α-adducin knockout mice presented progressive axon enlargement in the spinal cord and optic and sciatic nerves, followed by axon degeneration and loss. Using stimulated emission depletion super-resolution microscopy, we show that a periodic subcortical actin cytoskeleton is assembled in every neuron type inspected including retinal ganglion cells and dorsal root ganglia neurons. In neurons devoid of adducin, the actin ring diameter increased, although the inter-ring periodicity was maintained. In vitro, the actin ring diameter adjusted as axons grew, suggesting the lattice is dynamic. Our data support a model in which adducin activity is not essential for actin ring assembly and periodicity but is necessary to control the diameter of both actin rings and axons and actin filament growth within rings.

  6. The Actin-Binding Protein α-Adducin Is Required for Maintaining Axon Diameter.

    Science.gov (United States)

    Leite, Sérgio Carvalho; Sampaio, Paula; Sousa, Vera Filipe; Nogueira-Rodrigues, Joana; Pinto-Costa, Rita; Peters, Luanne Laurel; Brites, Pedro; Sousa, Mónica Mendes

    2016-04-19

    The actin-binding protein adducin was recently identified as a component of the neuronal subcortical cytoskeleton. Here, we analyzed mice lacking adducin to uncover the function of this protein in actin rings. α-adducin knockout mice presented progressive axon enlargement in the spinal cord and optic and sciatic nerves, followed by axon degeneration and loss. Using stimulated emission depletion super-resolution microscopy, we show that a periodic subcortical actin cytoskeleton is assembled in every neuron type inspected including retinal ganglion cells and dorsal root ganglia neurons. In neurons devoid of adducin, the actin ring diameter increased, although the inter-ring periodicity was maintained. In vitro, the actin ring diameter adjusted as axons grew, suggesting the lattice is dynamic. Our data support a model in which adducin activity is not essential for actin ring assembly and periodicity but is necessary to control the diameter of both actin rings and axons and actin filament growth within rings. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  7. Molecular imaging reveals elevated VEGFR-2 expression in retinal capillaries in diabetes: a novel biomarker for early diagnosis

    Science.gov (United States)

    Sun, Dawei; Nakao, Shintaro; Xie, Fang; Zandi, Souska; Bagheri, Abouzar; Kanavi, Mozhgan Rezaei; Samiei, Shahram; Soheili, Zahra-Soheila; Frimmel, Sonja; Zhang, Zhongyu; Ablonczy, Zsolt; Ahmadieh, Hamid; Hafezi-Moghadam, Ali

    2014-01-01

    Diabetic retinopathy (DR) is a microvascular complication of diabetes and a leading cause of vision loss. Biomarkers and methods for early diagnosis of DR are urgently needed. Using a new molecular imaging approach, we show up to 94% higher accumulation of custom designed imaging probes against vascular endothelial growth factor receptor 2 (VEGFR-2) in retinal and choroidal vessels of diabetic animals (PM. R., Samiei, S., Soheili, Z.-S., Frimmel, S., Zhang, Z., Ablonczy, Z., Ahmadieh, H., Hafezi-Moghadam, A. Molecular imaging reveals elevated VEGFR-2 expression in retinal capillaries in diabetes: a novel biomarker for early diagnosis. PMID:24903276

  8. The Time Course of Deafness and Retinal Degeneration in a Kunming Mouse Model for Usher Syndrome.

    Science.gov (United States)

    Yao, Lu; Zhang, Lei; Qi, Lin-Song; Liu, Wei; An, Jing; Wang, Bin; Xue, Jun-Hui; Zhang, Zuo-Ming

    2016-01-01

    Usher syndrome is a group of autosomal recessive diseases characterized by congenital deafness and retinitis pigmentosa. In a mouse model for Usher syndrome, KMush/ush, discovered in our laboratory, we measured the phenotypes, characterized the architecture and morphology of the retina, and quantified the level of expression of pde6b and ush2a between postnatal (P) days 7, and 56. Electroretinograms and auditory brainstem response were used to measure visual and auditory phenotypes. Fundus photography and light microscopy were used to measure the architecture and morphology of the retina. Quantitative real-time PCR was used to measure the expression levels of mRNA. KMush/ush mice had low amplitudes and no obvious waveforms of Electroretinograms after P14 compared with controls. Thresholds of auditory brainstem response in our model were higher than those of controls after P14. By P21, the retinal vessels of KMush/ush mice were attenuated and their optic discs had a waxy pallor. The retinas of KMush/ush mice atrophied and the choroidal vessels were clearly visible. Notably, the architecture of each retinal layer was not different as compared with control mice at P7, while the outer nuclear layer (ONL) and other retinal layers of KMush/ush mice were attenuated significantly between P14 and P21. ONL cells were barely seen in KMush/ush mice at P56. As compared with control mice, the expression of pde6b and ush2a in KMush/ush mice declined significantly after P7. This study is a first step toward characterizing the progression of disease in our mouse model. Future studies using this model may provide insights about the etiology of the disease and the relationships between genotypes and phenotypes providing a valuable resource that could contribute to the foundation of knowledge necessary to develop therapies to prevent the retinal degeneration in patients with Usher Syndrome.

  9. The Time Course of Deafness and Retinal Degeneration in a Kunming Mouse Model for Usher Syndrome.

    Directory of Open Access Journals (Sweden)

    Lu Yao

    Full Text Available Usher syndrome is a group of autosomal recessive diseases characterized by congenital deafness and retinitis pigmentosa. In a mouse model for Usher syndrome, KMush/ush, discovered in our laboratory, we measured the phenotypes, characterized the architecture and morphology of the retina, and quantified the level of expression of pde6b and ush2a between postnatal (P days 7, and 56. Electroretinograms and auditory brainstem response were used to measure visual and auditory phenotypes. Fundus photography and light microscopy were used to measure the architecture and morphology of the retina. Quantitative real-time PCR was used to measure the expression levels of mRNA. KMush/ush mice had low amplitudes and no obvious waveforms of Electroretinograms after P14 compared with controls. Thresholds of auditory brainstem response in our model were higher than those of controls after P14. By P21, the retinal vessels of KMush/ush mice were attenuated and their optic discs had a waxy pallor. The retinas of KMush/ush mice atrophied and the choroidal vessels were clearly visible. Notably, the architecture of each retinal layer was not different as compared with control mice at P7, while the outer nuclear layer (ONL and other retinal layers of KMush/ush mice were attenuated significantly between P14 and P21. ONL cells were barely seen in KMush/ush mice at P56. As compared with control mice, the expression of pde6b and ush2a in KMush/ush mice declined significantly after P7. This study is a first step toward characterizing the progression of disease in our mouse model. Future studies using this model may provide insights about the etiology of the disease and the relationships between genotypes and phenotypes providing a valuable resource that could contribute to the foundation of knowledge necessary to develop therapies to prevent the retinal degeneration in patients with Usher Syndrome.

  10. Case Report of Optic Disc Drusen with Simultaneous Peripapillary Subretinal Hemorrhage and Central Retinal Vein Occlusion

    Directory of Open Access Journals (Sweden)

    David Zhiwei Law

    2014-01-01

    Full Text Available A 52-year-old Chinese gentleman presented with right eye floaters and photopsia over one week. His visual acuities were 20/20 bilaterally. Posterior segment examination showed a right eye swollen optic disc and central retinal vein occlusion (CRVO associated with an area of subretinal hemorrhage adjacent to the optic disc. Fundus fluorescein (FA and indocyanine green angiographies (ICGA of the right eye did not demonstrate choroidal neovascularization (CNV, polypoidal choroidal vasculopathy (PCV, or retinal ischemia. Ultrasound B-scan revealed optic disc drusen (ODD. In view of good vision and absence of CNV, he was managed conservatively with spontaneous resolution after two months. Commonly, ODD may directly compress and mechanically rupture subretinal vessels at the optic disc, resulting in peripapillary subretinal hemorrhage, as was likely the case in our patient. Mechanical impairment of peripapillary circulation also results in retinal ischemia and may trigger the development of choroidal neovascularization (CNV and/or polypoidal choroidal vasculopathy (PCV, leading to subretinal haemorrhage. Compromise in central venous outflow with increased retinal central venous pressure from the direct mechanical effects of enlarging ODD results in central retinal vein occlusion (CRVO. Patients with subretinal hemorrhage and CRVO from ODD should be monitored closely for the development of potentially sight-threatening complications.

  11. Nuclear reactor vessel fuel thermal insulating barrier

    Science.gov (United States)

    Keegan, C. Patrick; Scobel, James H.; Wright, Richard F.

    2013-03-19

    The reactor vessel of a nuclear reactor installation which is suspended from the cold leg nozzles in a reactor cavity is provided with a lower thermal insulating barrier spaced from the reactor vessel that has a hemispherical lower section that increases in volume from the center line of the reactor to the outer extent of the diameter of the thermal insulating barrier and smoothly transitions up the side walls of the vessel. The space between the thermal insulating harrier and the reactor vessel forms a chamber which can be flooded with cooling water through passive valving to directly cool the reactor vessel in the event of a severe accident. The passive inlet valve for the cooling water includes a buoyant door that is normally maintained sealed under its own weight and floats open when the cavity is Hooded. Passively opening steam vents are also provided.

  12. Multimodality optical coherence tomography and fluorescence confocal scanning laser ophthalmoscopy in a zebrafish model of retinal vascular occlusion and remodeling

    Science.gov (United States)

    Li, Xiaoyue; Spitz, Kathleen; Bozic, Ivan; Tao, Yuankai K.

    2018-02-01

    Neovascularization in diabetic retinopathy (DR) and age-related macular degeneration (AMD) result in severe vision-loss and are two of the leading causes of blindness. The structural, metabolic, and vascular changes underlying retinal neovascularization are unknown and, thus, there is an unmet need to identify mechanisms of pathogenesis and novel anti-angiogenic therapies. Zebrafish is a robust ophthalmological model because its retina has comparable structure to the human retina and its fecundity and life-cycle enable development of mutant phenotypes of human pathologies. Here, we perform multimodal imaging with OCT and fluorescence confocal scanning laser ophthalmoscopy (cSLO) to identify changes in retinal structure and function in a zebrafish model of vascular leakage. Transgenic zebrafish with EGFP tagged plasma protein were imaged longitudinally at six time points over two weeks to visualize vascular perfusion changes from diethylaminobenzaldehyde (DEAB) treatment. Complementary contrast from OCT-A perfusion maps and cSLO imaging of plasma protein EGFP shows vascular occlusions posttreatment. cSLO images confirm presence of vessels despite loss of OCT-A signal. Plasma protein EGFP contrast also shows significant changes in vessel structure as compared to baseline images. OCT structural volumes show empty vessel cross-sections confirming non-perfusion. In addition, we present algorithms for automated biometric identification of OCT datasets using OCT-A vascular patterns in the presence of significant vascular perfusion changes. These results establish a framework for large-scale in vivo assays to identify novel anti-angiogenic compounds and understand the mechanisms ofneovascularization associated with retinal ocular pathologies.

  13. Chaetomium retinitis.

    Science.gov (United States)

    Tabbara, Khalid F; Wedin, Keith; Al Haddab, Saad

    2010-01-01

    To report a case of Chaetomium atrobrunneum retinitis in a patient with Hodgkin lymphoma. We studied the ocular manifestations of an 11-year-old boy with retinitis. Biomicroscopy, ophthalmoscopy, and fundus photography were done. Magnetic resonance imaging of the brain was performed. A vitreous biopsy was subjected to viral, bacterial, and fungal cultures. Vitreous culture grew C. atrobrunneum. Magnetic resonance imaging showed multiple cerebral lesions consistent with an infectious process. The patient was given intravenous voriconazole and showed improvement of the ocular and central nervous system lesions. We report a case of central nervous system and ocular lesions by C. atrobrunneum. The retinitis was initially misdiagnosed as cytomegaloviral retinitis. Vitreous biopsy helped in the early diagnosis and prompt treatment of a life- and vision-threatening infection.

  14. The relaxing effect of perivascular tissue on porcine retinal arterioles in vitro is mimicked by N-methyl-D-aspartate and is blocked by prostaglandin synthesis inhibition

    DEFF Research Database (Denmark)

    Jensen, Kim Holmgaard; Aalkjær, Christian; Lambert, John D. C.

    2008-01-01

    . However, previous in vitro studies of the influence of perivascular retinal tissue on retinal tone regulation have been hampered by the release of an endogenous relaxing factor that renders the arteriole insensitive to vasoconstrictors. The purpose of the present study was to test whether N-methyl-D-aspartate...... (NMDA) and gamma-amino butyric acid (GABA) receptors, and a cyclooxygenase (COX) product influence this effect of perivascular retinal tissue in vitro. METHODS: Porcine retinal arterioles were mounted in a wire myograph for isometric force measurements. The contractile effect of the prostaglandin...... analogue U46619 was studied on vessels with preserved perivascular retinal tissue and after this tissue had been removed. The influence of the perivascular tissue was studied after addition of NMDA (a specific agonist for a subtype of the glutamate receptor), DL-amino-5-phosphonovaleric acid (DL...

  15. Molecular imaging reveals elevated VEGFR-2 expression in retinal capillaries in diabetes: a novel biomarker for early diagnosis.

    Science.gov (United States)

    Sun, Dawei; Nakao, Shintaro; Xie, Fang; Zandi, Souska; Bagheri, Abouzar; Kanavi, Mozhgan Rezaei; Samiei, Shahram; Soheili, Zahra-Soheila; Frimmel, Sonja; Zhang, Zhongyu; Ablonczy, Zsolt; Ahmadieh, Hamid; Hafezi-Moghadam, Ali

    2014-09-01

    Diabetic retinopathy (DR) is a microvascular complication of diabetes and a leading cause of vision loss. Biomarkers and methods for early diagnosis of DR are urgently needed. Using a new molecular imaging approach, we show up to 94% higher accumulation of custom designed imaging probes against vascular endothelial growth factor receptor 2 (VEGFR-2) in retinal and choroidal vessels of diabetic animals (P<0.01), compared to normal controls. More than 80% of the VEGFR-2 in the diabetic retina was in the capillaries, compared to 47% in normal controls (P<0.01). Angiography in rabbit retinas revealed microvascular capillaries to be the location for VEGF-A-induced leakage, as expressed by significantly higher rate of fluorophore spreading with VEGF-A injection when compared to vehicle control (26±2 vs. 3±1 μm/s, P<0.05). Immunohistochemistry showed VEGFR-2 expression in capillaries of diabetic animals but not in normal controls. Macular vessels from diabetic patients (n=7) showed significantly more VEGFR-2 compared to nondiabetic controls (n=5) or peripheral retinal regions of the same retinas (P<0.01 in both cases). Here we introduce a new approach for early diagnosis of DR and VEGFR-2 as a molecular marker. VEGFR-2 could become a key diagnostic target, one that might help to prevent retinal vascular leakage and proliferation in diabetic patients. © FASEB.

  16. Retinitis Pigmentosa.

    Science.gov (United States)

    Carr, Ronald E.

    1979-01-01

    The author describes the etiology of retinitis pigmentosa, a visual dysfunction which results from progressive loss of the retinal photoreceptors. Sections address signs and symptoms, ancillary findings, heredity, clinical diagnosis, therapy, and research. (SBH)

  17. Noninvasive Imaging of Retinal Morphology and Microvasculature in Obese Mice Using Optical Coherence Tomography and Optical Microangiography

    Science.gov (United States)

    Zhi, Zhongwei; Chao, Jennifer R.; Wietecha, Tomasz; Hudkins, Kelly L.; Alpers, Charles E.; Wang, Ruikang K.

    2014-01-01

    Purpose. To evaluate early diabetes-induced changes in retinal thickness and microvasculature in a type 2 diabetic mouse model by using optical coherence tomography (OCT)/optical microangiography (OMAG). Methods. Twenty-two-week-old obese (OB) BTBR mice (n = 10) and wild-type (WT) control mice (n = 10) were imaged. Three-dimensional (3D) data volumes were captured with spectral domain OCT using an ultrahigh-sensitive OMAG scanning protocol for 3D volumetric angiography of the retina and dense A-scan protocol for measurement of the total retinal blood flow (RBF) rate. The thicknesses of the nerve fiber layer (NFL) and that of the NFL to the inner plexiform layer (IPL) were measured and compared between OB and WT mice. The linear capillary densities within intermediate and deep capillary layers were determined by the number of capillaries crossing a 500-μm line. The RBF rate was evaluated using an en face Doppler approach. These quantitative measurements were compared between OB and WT mice. Results. The retinal thickness of the NFL to IPL was significantly reduced in OB mice (P < 0.01) compared to that in WT mice, whereas the NFL thickness between the two was unchanged. 3D depth-resolved OMAG angiography revealed the first in vivo 3D model of mouse retinal microcirculation. Although no obvious differences in capillary vessel densities of the intermediate and deep capillary layers were detected between normal and OB mice, the total RBF rate was significantly lower (P < 0.05) in OB mice than in WT mice. Conclusions. We conclude that OB BTBR mice have significantly reduced NFL–IPL thicknesses and total RBF rates compared with those of WT mice, as imaged by OCT/OMAG. OMAG provides an unprecedented capability for high-resolution depth-resolved imaging of mouse retinal vessels and blood flow that may play a pivotal role in providing a noninvasive method for detecting early microvascular changes in patients with diabetic retinopathy. PMID:24458155

  18. Rapid sealing of porcine renal blood vessels, ex vivo, using a high power, 1470-nm laser, and laparoscopic prototype

    Science.gov (United States)

    Hardy, Luke A.; Hutchens, Thomas C.; Larson, Eric R.; Gonzalez, David A.; Chang, Chun-Hung; Nau, William H.; Fried, Nathaniel M.

    2017-05-01

    Energy-based, radiofrequency (RF) and ultrasonic (US) devices currently provide rapid sealing of blood vessels during laparoscopic procedures. We are exploring infrared lasers as an alternate energy modality for vessel sealing, capable of generating less collateral thermal damage. Previous studies demonstrated feasibility of sealing vessels in an in vivo porcine model using a 1470-nm laser. However, the initial prototype was designed for testing in open surgery and featured tissue clasping and light delivery mechanisms incompatible with laparoscopic surgery. In this study, a laparoscopic prototype similar to devices currently in surgical use was developed, and performance tests were conducted on porcine renal blood vessels, ex vivo. The 5-mm outer-diameter laparoscopic prototype featured a traditional Maryland jaw configuration that enables tissue manipulation and blunt dissection. Laser energy was delivered through a 550-μm-core-diameter optical fiber with side-delivery from the lower jaw and beam dimensions of 18-mm length×1.2-mm width. The 1470-nm diode laser delivered 68 W with 3-s activation time, consistent with vessel seal times associated with RF and US-based devices. A total of 69 fresh porcine renal vessels with mean diameter of 3.3±1.7 mm were tested, ex vivo. Vessels smaller than 5-mm diameter were consistently sealed (48/51) with burst pressures greater than malignant hypertension blood pressure (180 mmHg), averaging 1038±474 mmHg. Vessels larger than 5 mm were not consistently sealed (6/18), yielding burst pressures of only 174±221 mmHg. Seal width, thermal damage zone, and thermal spread averaged 1.7±0.8, 3.4±0.7, and 1.0±0.4 mm, respectively. Results demonstrated that the 5-mm optical laparoscopic prototype consistently sealed vessels less than 5-mm diameter with low thermal spread. Further in vivo studies are planned to test the performance across a variety of vessels and tissues.

  19. Krypton laser photocoagulation induces retinal vascular remodeling rather than choroidal neovascularization.

    Science.gov (United States)

    Behar-Cohen, F; Benezra, D; Soubrane, G; Jonet, L; Jeanny, J C

    2006-08-01

    The purpose of this study is to analyze the retina and choroid response following krypton laser photocoagulation. Ninety-two C57BL6/Sev129 and 32 C57BL/6J, 5-6-week-old mice received one single krypton (630 nm) laser lesion: 50 microm, 0.05 s, 400 mW. On the following day, every day thereafter for 1 week and every 2-3 days for the following 3 weeks, serial sections throughout the lesion were systematically collected and studied. Immunohistology using specific markers or antibodies for glial fibrillary acidic protein (GFAP) (astrocytes, glia and Muller's cells), von Willebrand (vW) (vascular endothelial cells), TUNEL (cells undergoing caspase dependent apoptosis), PCNA (proliferating cell nuclear antigen) p36, CD4 and F4/80 (infiltrating inflammatory and T cells), DAPI (cell nuclei) and routine histology were carried out. Laser confocal microscopy was also performed on flat mounts. Temporal and spatial observations of the created photocoagulation lesions demonstrate that, after a few hours, activated glial cells within the retinal path of the laser beam express GFAP. After 48 h, GFAP-positive staining was also detected within the choroid lesion center. "Movement" of this GFAP-positive expression towards the lasered choroid was preceded by a well-demarcated and localized apoptosis of the retina outer nuclear layer cells within the laser beam path. Later, death of retinal outer nuclear cells and layer thinning at this site was followed by evagination of the inner nuclear retinal layer. Funneling of the entire inner nuclear and the thinned outer nuclear layers into the choroid lesion center was accompanied by "dragging" of the retinal capillaries. Thus, from days 10 to 14 after krypton laser photocoagulation onward, well-formed blood capillaries (of retinal origin) were observed within the lesion. Only a few of the vW-positive capillary endothelial cells stained also for PCNA p36. In the choroid, dilatation of the vascular bed occurred at the vicinity of the

  20. Scoping calculations for design and analysis of large reactor vessels for liquid-metal fast breeder reactor (LMFBR) plants

    International Nuclear Information System (INIS)

    Fiala, C.; Kulak, R.F.; Ma, D.C.; Pan, Y.C.; Seidensticker, R.W.; Wang, C.Y.; Zeuch, W.R.

    1982-01-01

    Reactor vessels for commercial-sized LMFBR plants are quite large - ranging 40 to 70 ft in diameter and 50 to 70 ft in overall depth. These stainless steel vessels contain liquid sodium at relatively low pressures, but at high temperatures. The resulting thin-walled vessels present the structural designer and analyst with special problems, particularly in providing a balanced design to accommodate seismic loads, design basis accident loads, and thermal loadings. A comprehensive set of scoping calculations - though preliminary in detail and depth of design - provides substantial guidance to the vessel designer for subsequent design iterations. Emphasis is placed on the analysis of the large-diameter top closure of the vessel - the deck structure

  1. Retinitis Pigmentosa

    Science.gov (United States)

    ... Linked Retinoschisis (XLRS) X-Linked Retinitis Pigmentosa (XLRP) Usher Syndrome Other Retinal Diseases Glossary News & Research News & Research ... degenerate. Forms of RP and related diseases include Usher syndrome, Leber congenital amaurosis, and Bardet-Biedl syndrome, among ...

  2. Retinal Diseases

    Science.gov (United States)

    ... Linked Retinoschisis (XLRS) X-Linked Retinitis Pigmentosa (XLRP) Usher Syndrome Other Retinal Diseases Glossary News & Research News & Research ... central portion of the retina called the macula. Usher Syndrome Usher syndrome is an inherited condition characterized by ...

  3. Age, ocular magnification, and circumpapillary retinal nerve fiber layer thickness

    Science.gov (United States)

    Wang, Mengyu; Elze, Tobias; Li, Dian; Baniasadi, Neda; Wirkner, Kerstin; Kirsten, Toralf; Thiery, Joachim; Loeffler, Markus; Engel, Christoph; Rauscher, Franziska G.

    2017-12-01

    Optical coherence tomography (OCT) manufacturers graphically present circumpapillary retinal nerve fiber layer thickness (cpRNFLT) together with normative limits to support clinicians in diagnosing ophthalmic diseases. The impact of age on cpRNFLT is typically implemented by linear models. cpRNFLT is strongly location-specific, whereas previously published norms are typically restricted to coarse sectors and based on small populations. Furthermore, OCT devices neglect impacts of lens or eye size on the diameter of the cpRNFLT scan circle so that the diameter substantially varies over different eyes. We investigate the impact of age and scan diameter reported by Spectralis spectral-domain OCT on cpRNFLT in 5646 subjects with healthy eyes. We provide cpRNFLT by age and diameter at 768 angular locations. Age/diameter were significantly related to cpRNFLT on 89%/92% of the circle, respectively (pointwise linear regression), and to shifts in cpRNFLT peak locations. For subjects from age 42.1 onward but not below, increasing age significantly decreased scan diameter (r=-0.28, p<0.001), which suggests that pathological cpRNFLT thinning over time may be underestimated in elderly compared to younger subjects, as scan diameter decrease correlated with cpRNFLT increase. Our detailed numerical results may help to generate various correction models to improve diagnosing and monitoring optic neuropathies.

  4. Evaluation of Mechanical Properties and Medical Applications of Polycaprolactone Small Diameter Artificial Blood Vessels

    Directory of Open Access Journals (Sweden)

    Mahnazsadat Mirbagheri

    2017-03-01

    Full Text Available Increasing the cardiovascular diseases and decreasing the possibility of autograft surgery are important factors that cause the choice of artificial vascular graft as an alternative treatment method. In this regard, producing artificial grafts similar to natural vessels is an important purpose that has long been followed as a gold standard by many researchers worldwide. In addition, mechanical properties including strength, long patency, bio-compatibility and hydrophobicity are necessary properties to achieve ideal vascular grafts. Hence there are various factors such as polymer type and preparation methods, which contribute to suitable mechanical properties. The electrospinning as an optimized method on one side and biocompatible, degradable and semicrystalline polycaprolactone (PCL on the other side are used for their acceptable mechanical properties to manufacture synthetic vessels. In this study, PCL vascular grafts have been reviewed and a wide range of parameters affecting the improvement of mechanical properties and their performance have been described along with clinical applications. Therefore, by investigating and comparing single and composite PCL vascular grafts, we achieved acceptable results in the field of cell growth and adhesion as well as implanting grafts in animals such as rat and rabbit. By reviewing other studies, it was revealed that synthetic composite vessels made of PCL and natural polymers such as collagen and chitosan and synthetic polymers such as polyurethane (PU for long patency and acceptable cell adhesion have shown good clinical results.

  5. Cell Therapy Applications for Retinal Vascular Diseases: Diabetic Retinopathy and Retinal Vein Occlusion.

    Science.gov (United States)

    Park, Susanna S

    2016-04-01

    Retinal vascular conditions, such as diabetic retinopathy and retinal vein occlusion, remain leading causes of vision loss. No therapy exists to restore vision loss resulting from retinal ischemia and associated retinal degeneration. Tissue regeneration is possible with cell therapy. The goal would be to restore or replace the damaged retinal vasculature and the retinal neurons that are damaged and/or degenerating from the hypoxic insult. Currently, various adult cell therapies have been explored as potential treatment. They include mesenchymal stem cells, vascular precursor cells (i.e., CD34+ cells, hematopoietic cells or endothelial progenitor cells), and adipose stromal cells. Preclinical studies show that all these cells have a paracrine trophic effect on damaged ischemic tissue, leading to tissue preservation. Endothelial progenitor cells and adipose stromal cells integrate into the damaged retinal vascular wall in preclinical models of diabetic retinopathy and ischemia-reperfusion injury. Mesenchymal stem cells do not integrate as readily but appear to have a primary paracrine trophic effect. Early phase clinical trials have been initiated and ongoing using mesenchymal stem cells or autologous bone marrow CD34+ cells injected intravitreally as potential therapy for diabetic retinopathy or retinal vein occlusion. Adipose stromal cells or pluripotent stem cells differentiated into endothelial colony-forming cells have been explored in preclinical studies and show promise as possible therapies for retinal vascular disorders. The relative safety or efficacy of these various cell therapies for treating retinal vascular disorders have yet to be determined.

  6. Characteristics of retinal reflectance changes induced by transcorneal electrical stimulation in cat eyes.

    Directory of Open Access Journals (Sweden)

    Takeshi Morimoto

    Full Text Available Transcorneal electrical stimulation (TES activates retinal neurons leading to visual sensations. How the retinal cells are activated by TES has not been definitively determined. Investigating the reflectance changes of the retina is an established technique and has been used to determine the mechanism of retinal activation. The purpose of this study was to evaluate the reflectance changes elicited by TES in cat eyes. Eight eyes of Eight cats were studied under general anesthesia. Biphasic electrical pulses were delivered transcornealy. The fundus images observed with near-infrared light (800-880 nm were recorded every 25 ms for 26 s. To improve the signal-to-noise ratio, the images of 10 consecutive recordings were averaged. Two-dimensional topographic maps of the reflective changes were constructed by subtracting images before from those after the TES. The effects of different stimulus parameters, e.g., current intensity, pulse duration, frequency, and stimulus duration, on the reflective changes were studied. Our results showed that after TES, the reflective changes appeared on the retinal vessels and optic disc. The intensity of reflectance changes increased as the current intensity, pulse duration, and stimulation duration increased (P<0.05 for all. The maximum intensity of the reflective change was obtained when the stimulus frequency was 20 Hz. The time course of the reflectance changes was also altered by the stimulation parameters. The response started earlier and returned to the baseline later with higher current intensities, longer pulse durations, but the time of the peak of the response was not changed. These results showed that the reflective changes were due to the activation of retinal neurons by TES and might involve the vascular changes induced by an activation of the retinal neurons.

  7. MULTIMODAL IMAGING OF DISEASE-ASSOCIATED PIGMENTARY CHANGES IN RETINITIS PIGMENTOSA.

    Science.gov (United States)

    Schuerch, Kaspar; Marsiglia, Marcela; Lee, Winston; Tsang, Stephen H; Sparrow, Janet R

    2016-12-01

    Using multiple imaging modalities, we evaluated the changes in photoreceptor cells and retinal pigment epithelium (RPE) that are associated with bone spicule-shaped melanin pigmentation in retinitis pigmentosa. In a cohort of 60 patients with retinitis pigmentosa, short-wavelength autofluorescence, near-infrared autofluorescence (NIR-AF), NIR reflectance, spectral domain optical coherence tomography, and color fundus images were studied. Central AF rings were visible in both short-wavelength autofluorescence and NIR-AF images. Bone spicule pigmentation was nonreflective in NIR reflectance, hypoautofluorescent with short-wavelength autofluorescence and NIR-AF imaging, and presented as intraretinal hyperreflective foci in spectral domain optical coherence tomography images. In areas beyond the AF ring outer border, the photoreceptor ellipsoid zone band was absent in spectral domain optical coherence tomography and the visibility of choroidal vessels in short-wavelength autofluorescence, NIR-AF, and NIR reflectance images was indicative of reduced RPE pigmentation. Choroidal visibility was most pronounced in the zone approaching peripheral areas of bone spicule pigmentation; here RPE/Bruch membrane thinning became apparent in spectral domain optical coherence tomography. These findings are consistent with a process by which RPE cells vacate their monolayer and migrate into inner retina in response to photoreceptor cell degeneration. The remaining RPE spread undergo thinning and consequently become less pigmented. An explanation for the absence of NIR-AF melanin signal in relation to bone spicule pigmentation is not forthcoming.

  8. Retinal venous thrombosis in a young patient with coagulation factor XII deficiency.

    Science.gov (United States)

    Borrego-Sanz, L; Santos-Bueso, E; Sáenz-Francés, F; Martínez-de-la-Casa, J M; García-Feijoo, J; Gegúndez-Fernández, J A; García-Sánchez, J

    2014-08-01

    A 35-year-old woman, with no relevant medical history, was referred for sudden vision loss in the left eye. Ophthalmological examination showed best corrected visual acuity of 1.0 in the right eye and 0.3 in left eye, with normal anterior pole and intraocular pressure. Fundus examination of the left eye revealed a venous thrombosis in the superior temporal branch, with dilated and tortuous retinal veins. The patient was referred to the hematology unit for thrombophilia study, and was diagnosed with a coagulation XII or Hageman factor deficiency. The development of retinal vessel occlusions, in patients under 50 years of age, is frequently associated with thrombophilia or hypercoagulability disorders. Factor XII deficiency is a rare condition, and its presence could contribute to a higher risk of thromboembolic events. Copyright © 2013 Sociedad Española de Oftalmología. Published by Elsevier Espana. All rights reserved.

  9. THE ALGORITHM OF DETERMINATION OF EYE FUNDUS VESSELS BLOOD FLOW CHARACTERISTICS ON VIDEOSEQUENCE

    Directory of Open Access Journals (Sweden)

    O. V. Nedzvedz

    2018-01-01

    Full Text Available The method of determination of the dynamic characteristics like the vessel diameter change, the linear and volume blood velocities in the vessels of the eye fundus is considered. Such characteristics allow to determine blood flow changes in the microvasculature affecting the blood flow in the brain, kidneys and coronary vessels. Developed algorithm includes four stages: the video sequence stabilization, the vessels segmentation with the help of a neural network, the determination of the instantaneous velocity in the vessels based on the optical flow and the analysis of the results.

  10. Morphometric analysis of rat femoral vessels under a video magnification system

    Directory of Open Access Journals (Sweden)

    Rui Sergio Monteiro de Barros

    Full Text Available Abstract The right femoral vessels of 80 rats were identified and dissected. External lengths and diameters of femoral arteries and femoral veins were measured using either a microscope or a video magnification system. Findings were correlated to animals’ weights. Mean length was 14.33 mm for both femoral arteries and femoral veins, mean diameter of arteries was 0.65 mm and diameter of veins was 0.81 mm. In our sample, rats’ body weights were only correlated with the diameter of their femoral veins.

  11. An agent-based model of the response to angioplasty and bare-metal stent deployment in an atherosclerotic blood vessel.

    Directory of Open Access Journals (Sweden)

    Antonia E Curtin

    Full Text Available PURPOSE: While animal models are widely used to investigate the development of restenosis in blood vessels following an intervention, computational models offer another means for investigating this phenomenon. A computational model of the response of a treated vessel would allow investigators to assess the effects of altering certain vessel- and stent-related variables. The authors aimed to develop a novel computational model of restenosis development following an angioplasty and bare-metal stent implantation in an atherosclerotic vessel using agent-based modeling techniques. The presented model is intended to demonstrate the body's response to the intervention and to explore how different vessel geometries or stent arrangements may affect restenosis development. METHODS: The model was created on a two-dimensional grid space. It utilizes the post-procedural vessel lumen diameter and stent information as its input parameters. The simulation starting point of the model is an atherosclerotic vessel after an angioplasty and stent implantation procedure. The model subsequently generates the final lumen diameter, percent change in lumen cross-sectional area, time to lumen diameter stabilization, and local concentrations of inflammatory cytokines upon simulation completion. Simulation results were directly compared with the results from serial imaging studies and cytokine levels studies in atherosclerotic patients from the relevant literature. RESULTS: The final lumen diameter results were all within one standard deviation of the mean lumen diameters reported in the comparison studies. The overlapping-stent simulations yielded results that matched published trends. The cytokine levels remained within the range of physiological levels throughout the simulations. CONCLUSION: We developed a novel computational model that successfully simulated the development of restenosis in a blood vessel following an angioplasty and bare-metal stent deployment based on

  12. Sirtuin1 Over-Expression Does Not Impact Retinal Vascular and Neuronal Degeneration in a Mouse Model of Oxygen-Induced Retinopathy

    Science.gov (United States)

    Michan, Shaday; Juan, Aimee M.; Hurst, Christian G.; Cui, Zhenghao; Evans, Lucy P.; Hatton, Colman J.; Pei, Dorothy T.; Ju, Meihua; Sinclair, David A.; Smith, Lois E. H.; Chen, Jing

    2014-01-01

    Proliferative retinopathy is a leading cause of blindness, including retinopathy of prematurity (ROP) in children and diabetic retinopathy in adults. Retinopathy is characterized by an initial phase of vessel loss, leading to tissue ischemia and hypoxia, followed by sight threatening pathologic neovascularization in the second phase. Previously we found that Sirtuin1 (Sirt1), a metabolically dependent protein deacetylase, regulates vascular regeneration in a mouse model of oxygen-induced proliferative retinopathy (OIR), as neuronal depletion of Sirt1 in retina worsens retinopathy. In this study we assessed whether over-expression of Sirtuin1 in retinal neurons and vessels achieved by crossing Sirt1 over-expressing flox mice with Nestin-Cre mice or Tie2-Cre mice, respectively, may protect against retinopathy. We found that over-expression of Sirt1 in Nestin expressing retinal neurons does not impact vaso-obliteration or pathologic neovascularization in OIR, nor does it influence neuronal degeneration in OIR. Similarly, increased expression of Sirt1 in Tie2 expressing vascular endothelial cells and monocytes/macrophages does not protect retinal vessels in OIR. In addition to the genetic approaches, dietary supplement with Sirt1 activators, resveratrol or SRT1720, were fed to wild type mice with OIR. Neither treatment showed significant vaso-protective effects in retinopathy. Together these results indicate that although endogenous Sirt1 is important as a stress-induced protector in retinopathy, over-expression of Sirt1 or treatment with small molecule activators at the examined doses do not provide additional protection against retinopathy in mice. Further studies are needed to examine in depth whether increasing levels of Sirt1 may serve as a potential therapeutic approach to treat or prevent retinopathy. PMID:24416337

  13. Sirtuin1 over-expression does not impact retinal vascular and neuronal degeneration in a mouse model of oxygen-induced retinopathy.

    Science.gov (United States)

    Michan, Shaday; Juan, Aimee M; Hurst, Christian G; Cui, Zhenghao; Evans, Lucy P; Hatton, Colman J; Pei, Dorothy T; Ju, Meihua; Sinclair, David A; Smith, Lois E H; Chen, Jing

    2014-01-01

    Proliferative retinopathy is a leading cause of blindness, including retinopathy of prematurity (ROP) in children and diabetic retinopathy in adults. Retinopathy is characterized by an initial phase of vessel loss, leading to tissue ischemia and hypoxia, followed by sight threatening pathologic neovascularization in the second phase. Previously we found that Sirtuin1 (Sirt1), a metabolically dependent protein deacetylase, regulates vascular regeneration in a mouse model of oxygen-induced proliferative retinopathy (OIR), as neuronal depletion of Sirt1 in retina worsens retinopathy. In this study we assessed whether over-expression of Sirtuin1 in retinal neurons and vessels achieved by crossing Sirt1 over-expressing flox mice with Nestin-Cre mice or Tie2-Cre mice, respectively, may protect against retinopathy. We found that over-expression of Sirt1 in Nestin expressing retinal neurons does not impact vaso-obliteration or pathologic neovascularization in OIR, nor does it influence neuronal degeneration in OIR. Similarly, increased expression of Sirt1 in Tie2 expressing vascular endothelial cells and monocytes/macrophages does not protect retinal vessels in OIR. In addition to the genetic approaches, dietary supplement with Sirt1 activators, resveratrol or SRT1720, were fed to wild type mice with OIR. Neither treatment showed significant vaso-protective effects in retinopathy. Together these results indicate that although endogenous Sirt1 is important as a stress-induced protector in retinopathy, over-expression of Sirt1 or treatment with small molecule activators at the examined doses do not provide additional protection against retinopathy in mice. Further studies are needed to examine in depth whether increasing levels of Sirt1 may serve as a potential therapeutic approach to treat or prevent retinopathy.

  14. Retinal Endovascular Surgery with Tissue Plasminogen Activator Injection for Central Retinal Artery Occlusion

    Directory of Open Access Journals (Sweden)

    Yuta Takata

    2018-06-01

    Full Text Available Purpose: To report 2 cases of central retinal artery occlusion (CRAO who underwent retinal endovascular surgery with injection of tissue plasminogen activator (tPA into the retinal artery and showed a remarkable improvement in visual acuity and retinal circulation. Methods: Standard 25-G vitrectomy was performed under local anesthesia. Simultaneously, tPA (80,000 units/mL solution was injected into the retinal artery of the optic disc for 2–3 min using a microneedle. Changes in visual acuity, fundus photography, optical coherence tomography (OCT, fluorescein angiography, and laser speckle flowgraphy (LSFG results were examined. Results: Both cases could be treated within 12 h after the onset of CRAO. Case 1 was a 47-year-old woman. Her visual acuity improved from counting fingers before operation to 0.08 logMAR 1 month after the surgery. However, thinning of the retina at the macula was observed by OCT. Case 2 was a 70-year-old man. His visual acuity improved from counting fingers to 0.1 logMAR 2 months after the surgery. Both fluorescein angiography and LSFG showed improvement in retinal circulation after the surgery in case 2. Conclusions: Retinal endovascular surgery with injection of tPA into the retinal artery was feasible and may be a way to improve visual acuity and retinal circulation when performed in the acute phase of CRAO.

  15. Refinements of the radiographic cadaver injection technique for investigating minute lymphatic vessels.

    Science.gov (United States)

    Suami, Hiroo; Taylor, G Ian; O'Neill, Jennifer; Pan, Wei-Ren

    2007-07-01

    The authors previously reported a new technique with which to delineate the lymphatic vessels, using hydrogen peroxide to identify them and a lead oxide suspension to demonstrate them on radiographs. This technique provided excellent studies of the lymph vessels in human cadavers, but there was still room for improvement. Lymph collecting vessels run superficially in some regions, where they may be damaged while the surgeon is attempting to find them. Vessels smaller than 0.3 mm in diameter could not be cannulated with a 30-gauge needle, which was the smallest the authors had available, and the lead oxide suspension often blocked this cannula. The authors also encountered problems holding the cannula steady. The authors solved these problems by using a mixture of hydrogen peroxide and ink to better identify the lymphatics, an extruded glass tube instead of a metal needle to cannulate them, an agate pestle and mortar to grind the lead oxide into finer particles, powdered milk to suspend the lead oxide, and a micromanipulator to facilitate accurate and steady cannulation of the vessels. This study developed these modifications to focus on tributaries of the collecting lymphatic channels that are smaller than 0.3 mm in diameter.

  16. Radial Peripapillary Capillary Network in Patients with Retinitis Pigmentosa: An Optical Coherence Tomography Angiography Study.

    Science.gov (United States)

    Mastropasqua, Rodolfo; Borrelli, Enrico; Agnifili, Luca; Toto, Lisa; Di Antonio, Luca; Senatore, Alfonso; Palmieri, Michele; D'Uffizi, Alessandro; Carpineto, Paolo

    2017-01-01

    To investigate radial peripapillary capillary (RPC) network in patients affected by retinitis pigmentosa (RP). Eleven patients (22 eyes) with previous diagnosis of RP and 16 age-matched healthy subjects (16 eyes) were enrolled. The diagnosis of RP was made based on both clinical features and electrophysiological examination. All patients underwent a complete ophthalmologic examination, including optical coherence tomography angiography and visual field (VF). The primary outcomes were the RPC vessel density in the peripapillary and disk areas; the secondary outcomes were the peripapillary retinal nerve fiber layer (RNFL) thickness and the mean defect at VF. A total of 19 eyes of 11 RP patients (5 males, 6 females) and 16 eyes of 16 healthy subjects (10 males, 6 females) were included for the analysis. RPC vessel density in the disk area was 46.5 ± 7.1% in the RP group and 45.4 ± 10.6% in the control group ( p  = 0.754). RPC vessel density in the peripapillary area was significantly reduced in the RP group after the comparison with the control group (52.5 ± 5.0 and 57.2 ± 5.1%, respectively, p  = 0.011). RNFL thickness was 85.9 ± 20.4 μm in the RP group and 104.0 ± 6.4 μm in the control group ( p  = 0.002). RPC vessel density was significantly correlated with RNFL thickness values in RP patients, both in the disk and in the peripapillary area (Rho = 0.599 and p  = 0.007 in the disk area, Rho = 0.665 and p  = 0.002 in the peripapillary area, respectively). We showed that density of RPC is reduced in these patients in the peripapillary area. Moreover, the RPC vessel density correlates with the RNFL thickness.

  17. Detection of Blood Vessels in Color Fundus Images using a Local Radon Transform

    Directory of Open Access Journals (Sweden)

    Reza Pourreza

    2010-09-01

    Full Text Available Introduction: This paper addresses a method for automatic detection of blood vessels in color fundus images which utilizes two main tools: image partitioning and local Radon transform. Material and Methods: The input images are firstly divided into overlapping windows and then the Radon transform is applied to each. The maximum of the Radon transform in each window corresponds to the probable available sub-vessel. To verify the detected sub-vessel, the maximum is compared with a predefined threshold. The verified sub-vessels are reconstructed using the Radon transform information. All detected and reconstructed sub-vessels are finally combined to make the final vessel tree. Results: The algorithm’s performance was evaluated numerically by applying it to 40 images of DRIVE database, a standard retinal image database. The vessels were extracted manually by two physicians. This database was used to test and compare the available and proposed algorithms for vessel detection in color fundus images. By comparing the output of the algorithm with the manual results, the two parameters TPR and FPR were calculated for each image and the average of TPRs and FPRs were used to plot the ROC curve. Discussion and Conclusion: Comparison of the ROC curve of this algorithm with other algorithms demonstrated the high achieved accuracy. Beside the high accuracy, the Radon transform which is integral-based makes the algorithm robust against noise.

  18. Adult Coats’ Disease Successfully Managed with the Dexamethasone Intravitreal Implant (Ozurdex® Combined with Retinal Photocoagulation

    Directory of Open Access Journals (Sweden)

    Sebastián Martínez-Castillo

    2012-03-01

    Full Text Available Purpose: To report a case of Coats’ disease managed with the dexamethasone intravitreal implant Ozurdex® (Allergan, Inc., Irvine, Calif., USA combined with retinal photocoagulation. Methods: A 46-year-old female with 20/200 visual acuity was diagnosed with Coats’ disease with secondary retinal vasoproliferative tumor. An initial approach was performed with an intravitreal injection of the sustained-release dexamethasone implant Ozurdex. After reattachment of the retina, the telangiectatic vessels were treated with laser photocoagulation. Results: The patient’s visual acuity improved to 20/25 after the intravitreal Ozurdex. No further recurrences of exudation were evident through the 12-month follow-up. Conclusions: Ozurdex may be an effective initial therapeutic approach for Coats’ disease with immediate anatomical response and visual improvement.

  19. Histomorphometric comparative study of blood vessels and their pattern in follicular cyst, odontogenic keratocyst, and ameloblastoma.

    Science.gov (United States)

    Seifi, Safora; Feizi, Farideh; Khafri, Thoraya; Aram, Mehrdad

    2013-03-01

    The present study aimed at assessment and histomorphometric analysis of intratumoral and peritumoral (cystic) blood vessels in odontogenic lesions and their pattern on their clinical behavior by immunohistochemistry and morphometry. In a descriptive and analytical cross-sectional study, 45 paraffin blocks of ameloblastoma, odontogenic keratocyst, and follicular cyst were selected and stained immunohistochemically for CD34. In each slide, images of 3 microscopic fields with the highest microvessel density in intratumoral and peritumoral (cystic) areas were captured at 40× magnification with attached camera system. Inner vascular diameter (IVD) and outer vascular diameter (OVD), cross-sectional area (CSA), and the wall thickness (WT) of the vessels were measured with Motic Plus 2 software. The vascular pattern in odontogenic lesions was analyzed. Outer vascular diameter, IVD, and CSA of the vessels in peritumoral (cystic) areas were greater in ameloblastoma than keratocyst (P = 0.001) and follicular cyst (P keratocyst and follicular cyst. Morphometric specifications of blood vessels (IVD, OVD, CSA) and their pattern in peritumoral (cystic) areas may influence the aggressive clinical behavior of ameloblastoma in comparison with keratocyst and follicular cyst.

  20. Radionuclide detection of blood-retinal barrier disruption in diabetes mellitus

    International Nuclear Information System (INIS)

    Freeman, M.L.; Barnes, W.E.; Eastman, G.; Evans, L.; Gergans, G.; Kelertas, A.; Emanuele, N.; Kaplan, E.

    1984-01-01

    Diabetic retinopathy is one of the leading causes of blindness in the United States today. Because early treatment of proliferative retinopathy offers the best chance for visual salvation, there is an essential need for methods of identifying eyes at high risk. Recent research has shown that subclinical leakage from retinal blood vessels is one of the earliest signs of retinopathy. The feasibility of using radionuclide techniques to quantitate blood-retinal barrier disruption is demonstrated by a study in which 23 diabetics and 7 nondiabetics were imaged with an Anger camera in the anterior Waters projection at 2 hours after the administration of Tc-99m DTPA. In the digitized images, regions of interest were placed over each orbit and over one of the cerebral hemispheres. Orbital counts were then compared to cerebral counts on a per pixel basis. Eye to brain ratios were found to be lowest for nondiabetics and highest for patients with proliferative retinopathy. Additionally, the dynamic analysis of the same radiopharmaceutical may allow investigators to further study the pathophysiology of the diabetic eye

  1. Neurovascular Network Explorer 1.0: a database of 2-photon single-vessel diameter measurements with MATLAB(®) graphical user interface.

    Science.gov (United States)

    Sridhar, Vishnu B; Tian, Peifang; Dale, Anders M; Devor, Anna; Saisan, Payam A

    2014-01-01

    We present a database client software-Neurovascular Network Explorer 1.0 (NNE 1.0)-that uses MATLAB(®) based Graphical User Interface (GUI) for interaction with a database of 2-photon single-vessel diameter measurements from our previous publication (Tian et al., 2010). These data are of particular interest for modeling the hemodynamic response. NNE 1.0 is downloaded by the user and then runs either as a MATLAB script or as a standalone program on a Windows platform. The GUI allows browsing the database according to parameters specified by the user, simple manipulation and visualization of the retrieved records (such as averaging and peak-normalization), and export of the results. Further, we provide NNE 1.0 source code. With this source code, the user can database their own experimental results, given the appropriate data structure and naming conventions, and thus share their data in a user-friendly format with other investigators. NNE 1.0 provides an example of seamless and low-cost solution for sharing of experimental data by a regular size neuroscience laboratory and may serve as a general template, facilitating dissemination of biological results and accelerating data-driven modeling approaches.

  2. Retinal pigmentary changes in chronic uveitis mimicking retinitis pigmentosa.

    Science.gov (United States)

    Sevgi, D Damla; Davoudi, Samaneh; Comander, Jason; Sobrin, Lucia

    2017-09-01

    To present retinal pigmentary changes mimicking retinitis pigmentosa (RP) as a finding of advanced uveitis. We retrospectively reviewed charts of patients without a family history of inherited retinal degenerations who presented with retinal pigment changes and signs of past or present intraocular inflammation. Comprehensive eye examination including best-corrected visual acuity, slit-lamp examination and dilated fundus examination was performed on all patients in addition to color fundus photography, optical coherence tomography, fluorescein angiography (FA), and full-field electroretinogram testing. We identified five patients with ages ranging from 33 to 66 years, who presented with RP-like retinal pigmentary changes which were eventually attributed to longstanding uveitis. The changes were bilateral in three cases and unilateral in two cases. Four of five cases presented with active inflammation, and the remaining case showed evidence of active intraocular inflammation during follow-up. This study highlights the overlapping features of advanced uveitis and RP including the extensive pigmentary changes. Careful review of possible past uveitis history, detailed examination of signs of past or present inflammation and ancillary testing, with FA often being most helpful, are required for the correct diagnosis. This is important, because intervention can prevent further damage if the cause of the pigmentary changes is destructive inflammation.

  3. Axial Length Variation Impacts on Superficial Retinal Vessel Density and Foveal Avascular Zone Area Measurements Using Optical Coherence Tomography Angiography.

    Science.gov (United States)

    Sampson, Danuta M; Gong, Peijun; An, Di; Menghini, Moreno; Hansen, Alex; Mackey, David A; Sampson, David D; Chen, Fred K

    2017-06-01

    To evaluate the impact of image magnification correction on superficial retinal vessel density (SRVD) and foveal avascular zone area (FAZA) measurements using optical coherence tomography angiography (OCTA). Participants with healthy retinas were recruited for ocular biometry, refraction, and RTVue XR Avanti OCTA imaging with the 3 × 3-mm protocol. The foveal and parafoveal SRVD and FAZA were quantified with custom software before and after correction for magnification error using the Littman and the modified Bennett formulae. Relative changes between corrected and uncorrected SRVD and FAZA were calculated. Forty subjects were enrolled and the median (range) age of the participants was 30 (18-74) years. The mean (range) spherical equivalent refractive error was -1.65 (-8.00 to +4.88) diopters and mean (range) axial length was 24.42 mm (21.27-28.85). Images from 13 eyes were excluded due to poor image quality leaving 67 for analysis. Relative changes in foveal and parafoveal SRVD and FAZA after correction ranged from -20% to +10%, -3% to +2%, and -20% to +51%, respectively. Image size correction in measurements of foveal SRVD and FAZA was greater than 5% in 51% and 74% of eyes, respectively. In contrast, 100% of eyes had less than 5% correction in measurements of parafoveal SRVD. Ocular biometry should be performed with OCTA to correct image magnification error induced by axial length variation. We advise caution when interpreting interocular and interindividual comparisons of SRVD and FAZA derived from OCTA without image size correction.

  4. Vessel Wall Reaction after Vena Cava Filter Placement

    International Nuclear Information System (INIS)

    Hoekstra, Arend; Elstrodt, Jan M.; Nikkels, Peter G.J.; Tiebosch, Anton T.M.G.

    2002-01-01

    Purpose: To evaluate the interaction between the Cordis Keeper vena caval filter and vessel wall in aporcine model.Methods: Implantation of the filter was performed in five pigs. Radiologic data concerning inferior vena cava(IVC) diameter and filter patency, filter leg span, and stability were collected. At 2 or 6 months post-implantation, histopathologic analysis of the IVC wall was performed.Results: All filters remained patent with no evidence of migration. However, at 6 months follow-up, two legs of one filter penetrated the vessel wall and were adherent to the liver. These preliminary results suggest that with the observed gradual increase in the filter span, the risk of caval wall penetration increases with time, especially in a relatively small IVC(average diameter 16 mm).Conclusion: The Cordis Keeper filter was well tolerated, but seems to be prone to caval wall penetration in the long term

  5. Extravasal occlusion of large vessels with titanic clips: efficiency, indications, and contraindications.

    Science.gov (United States)

    Vasilenko, Yu V; Kim, A I; Kotov, S A

    2002-11-01

    The mechanism of extravasal occlusion of blood vessels with titanic clips "Atrauclip" and "Ligaclip extra" was studied in order to reveal indications and contraindications to their use. Occlusion with the clips of both types was ineffective in vessels with a diameter of >7.0 mm. Arteritis or the presence of an intravascular occlusion facility in the vessel were also the contraindications for clip occlusion. In overcases the procedure of occlusion with titanic clips was efficient and atraumatic.

  6. Repetitive magnetic stimulation improves retinal function in a rat model of retinal dystrophy

    Science.gov (United States)

    Rotenstreich, Ygal; Tzameret, Adi; Levi, Nir; Kalish, Sapir; Sher, Ifat; Zangen, Avraham; Belkin, Michael

    2014-02-01

    Vision incapacitation and blindness associated with retinal dystrophies affect millions of people worldwide. Retinal degeneration is characterized by photoreceptor cell death and concomitant remodeling of remaining retinal cells. Repetitive Magnetic Stimulation (RMS) is a non-invasive technique that creates alternating magnetic fields by brief electric currents transmitted through an insulated coil. These magnetic field generate action potentials in neurons, and modulate the expression of neurotransmitter receptors, growth factors and transcription factors which mediate plasticity. This technology has been proven effective and safe in various psychiatric disorders. Here we determined the effect of RMS on retinal function in Royal College of Surgeons (RCS) rats, a model for retinal dystrophy. Four week-old RCS and control Spargue Dawley (SD) rats received sham or RMS treatment over the right eye (12 sessions on 4 weeks). RMS treatment at intensity of at 40% of the maximal output of a Rapid2 stimulator significantly increased the electroretinogram (ERG) b-wave responses by up to 6- or 10-fold in the left and right eye respectively, 3-5 weeks following end of treatment. RMS treatment at intensity of 25% of the maximal output did not significant effect b-wave responses following end of treatment with no adverse effect on ERG response or retinal structure of SD rats. Our findings suggest that RMS treatment induces delayed improvement of retinal functions and may induce plasticity in the retinal tissue. Furthermore, this non-invasive treatment may possibly be used in the future as a primary or adjuvant treatment for retinal dystrophy.

  7. A SURVEY OF RETINA BASED DISEASE IDENTIFICATION USING BLOOD VESSEL SEGMENTATION

    Directory of Open Access Journals (Sweden)

    P Kuppusamy

    2016-11-01

    Full Text Available The colour retinal photography is one of the most essential features to identify the confirmation of various eye diseases. The iris is primary attribute to authenticate the human. This research work presents the survey and comparison of various blood vessel related feature identification, segmentation, extraction and enhancement methods. Additionally, this study is observed the various databases performance for storing the images and testing in minimal time. This paper is also provides the better performance techniques based on the survey.

  8. Multimodal imaging of small hard retinal drusen in young healthy adults

    DEFF Research Database (Denmark)

    Pedersen, Hilde R; Gilson, Stuart J; Dubra, Alfredo

    2018-01-01

    BACKGROUND: Small hard macular drusen can be observed in the retina of adults as young as 18 years of age. Here, we seek to describe the in vivo topography and geometry of these drusen. METHODS: Retinal images were acquired in young, healthy adults using colour fundus photography, spectral domain...... the foveal centre were characterised. RESULTS: Small hard drusen were seen on colour photographs in 21 out of 97 participants and 26 drusen in 12 eyes in 11 participants were imaged using the full protocol. Drusen were easily identifiable in all modalities, except a few very small ones, which were...... not visible on SD-OCT. On AOSLO images, these drusen appeared as round, oval or lobular areas (up to three lobules) of diameter 22-61 µm where cone photoreceptor reflectivity and density was decreased (p=0.049). This was usually associated with discrete thickening of the retinal pigment epithelium (RPE...

  9. High-resolution retinal imaging using adaptive optics and Fourier-domain optical coherence tomography

    Science.gov (United States)

    Olivier, Scot S.; Werner, John S.; Zawadzki, Robert J.; Laut, Sophie P.; Jones, Steven M.

    2010-09-07

    This invention permits retinal images to be acquired at high speed and with unprecedented resolution in three dimensions (4.times.4.times.6 .mu.m). The instrument achieves high lateral resolution by using adaptive optics to correct optical aberrations of the human eye in real time. High axial resolution and high speed are made possible by the use of Fourier-domain optical coherence tomography. Using this system, we have demonstrated the ability to image microscopic blood vessels and the cone photoreceptor mosaic.

  10. Automated classification and quantitative analysis of arterial and venous vessels in fundus images

    Science.gov (United States)

    Alam, Minhaj; Son, Taeyoon; Toslak, Devrim; Lim, Jennifer I.; Yao, Xincheng

    2018-02-01

    It is known that retinopathies may affect arteries and veins differently. Therefore, reliable differentiation of arteries and veins is essential for computer-aided analysis of fundus images. The purpose of this study is to validate one automated method for robust classification of arteries and veins (A-V) in digital fundus images. We combine optical density ratio (ODR) analysis and blood vessel tracking algorithm to classify arteries and veins. A matched filtering method is used to enhance retinal blood vessels. Bottom hat filtering and global thresholding are used to segment the vessel and skeleton individual blood vessels. The vessel tracking algorithm is used to locate the optic disk and to identify source nodes of blood vessels in optic disk area. Each node can be identified as vein or artery using ODR information. Using the source nodes as starting point, the whole vessel trace is then tracked and classified as vein or artery using vessel curvature and angle information. 50 color fundus images from diabetic retinopathy patients were used to test the algorithm. Sensitivity, specificity, and accuracy metrics were measured to assess the validity of the proposed classification method compared to ground truths created by two independent observers. The algorithm demonstrated 97.52% accuracy in identifying blood vessels as vein or artery. A quantitative analysis upon A-V classification showed that average A-V ratio of width for NPDR subjects with hypertension decreased significantly (43.13%).

  11. Bilateral patching in retinal detachment: fluid mechanics and retinal "settling".

    Science.gov (United States)

    Foster, William J

    2011-07-20

    When a patient suffers a retinal detachment and surgery is delayed, it is known clinically that bilaterally patching the patient may allow the retina to partially reattach or "settle." Although this procedure has been performed since the 1860s, there is still debate as to how such a maneuver facilitates the reattachment of the retina. Finite element calculations using commercially available analysis software are used to elucidate the influence of reduction in eye movement caused by bilateral patching on the flow of subretinal fluid in a physical model of retinal detachment. It was found that by coupling fluid mechanics with structural mechanics, a physically consistent explanation of increased retinal detachment with eye movements can be found in the case of traction on the retinal hole. Large eye movements increase vitreous traction and detachment forces on the edge of the retinal hole, creating a subretinal vacuum and facilitating increased subretinal fluid. Alternative models, in which intraocular fluid flow is redirected into the subretinal space, are not consistent with these simulations. The results of these simulations explain the physical principles behind bilateral patching and provide insight that can be used clinically. In particular, as is known clinically, bilateral patching may facilitate a decrease in the height of a retinal detachment. The results described here provide a description of a physical mechanism underlying this technique. The findings of this study may aid in deciding whether to bilaterally patch patients and in counseling patients on pre- and postoperative care.

  12. Analysis of three ex-vessel loss-of-coolant accidents in the first wall cooling system of NET/ITER

    International Nuclear Information System (INIS)

    Komen, E.M.J.; Koning, H.

    1993-01-01

    An ex-vessel LOCA may be caused by a rupture of a cooling pipe located outside the vacuum vessel. No plasma shutdown and no other counteractions have been assumed in order to study the worst case conditions of the accidents. The next three ex-vessel LOCAs in the primary cooling system of the first wall have been analysed: 1. a large break ex-vessel LOCA caused by a rupture of the cold leg (inner diameter 0.314 m) of the main circuit; 2. an intermediate break ex-vessel LOCA caused by a rupture of a sector inlet feeder (inner diameter 0.158 m); 3. an intermediate break ex-vessel LOCA caused by a rupture of the surge line (inner diameter 0.180 m) of the pressurizer. The analyses have been performed using the thermal-hydraulic system analysis code RELAP5/MOD3. In the first two scenarios, melting in the first wall starts about 90 s after break initiation. In the third scenario, melting in the first wall start about 323 s after break initiation. Special emphasis has been paid to the characteristics of the break flows, the transient thermal-hydraulic behaviour of the cooling system, and the temperature development in the first wall. (orig.)

  13. The Extract of Aster Koraiensis Prevents Retinal Pericyte Apoptosis in Diabetic Rats and Its Active Compound, Chlorogenic Acid Inhibits AGE Formation and AGE/RAGE Interaction

    Directory of Open Access Journals (Sweden)

    Junghyun Kim

    2016-09-01

    Full Text Available Retinal capillary cell loss is a hallmark of early diabetic retinal changes. Advanced glycation end products (AGEs are believed to contribute to retinal microvascular cell loss in diabetic retinopathy. In this study, the protective effects of Aster koraiensis extract (AKE against damage to retinal vascular cells were investigated in streptozotocin (STZ-induced diabetic rats. To examine this issue further, AGE accumulation, nuclear factor-kappaB (NF-κB and inducible nitric oxide synthase (iNOS were investigated using retinal trypsin digests from streptozotocin-induced diabetic rats. In the diabetic rats, TUNEL (Terminal deoxynucleotidyl transferase mediated dUTP Nick End Labeling-positive retinal microvascular cells were markedly increased. Immunohistochemical studies revealed that AGEs were accumulated within the retinal microvascular cells, and this accumulation paralleled the activation of NF-κB and the expression of iNOS in the diabetic rats. However, AKE prevented retinal microvascular cell apoptosis through the inhibition of AGE accumulation and NF-κB activation. Moreover, to determine the active compounds of AKE, two major compounds, chlorogenic acid and 3,5-di-O-caffeoylquinic acid, were tested in an in vitro assay. Among these compounds, chlorogenic acid significantly reduced AGE formation as well as AGE/RAGE (receptor for AGEs binding activity. These results suggest that AKE, particularly chlorogenic acid, is useful in inhibiting AGE accumulation in retinal vessels and exerts a preventive effect against the injuries of diabetic retinal vascular cells.

  14. Fluorescein angiography and retinal vascular development in premature infants.

    Science.gov (United States)

    Purcaro, Velia; Velia, Purcaro; Baldascino, Antonio; Antonio, Baldascino; Papacci, Patrizia; Patrizia, Papacci; Giannantonio, Carmen; Carmen, Giannantonio; Molisso, Anna; Anna, Molisso; Molle, Fernando; Fernando, Molle; Lepore, Domenico; Domenico, Lepore; Romagnoli, Costantino; Costantino, Romagnoli

    2012-10-01

    To investigate the role of fluorescein angiography (FA) in the management of retinopathy of prematurity (ROP) in preterm newborns. An observational case series of 13 extremely low birth weight infants. From September 2009 to March 2010, 13 newborn infants with a gestational age <29 weeks end/or birth weight <1000 g underwent serial fluorescein angiography with RetCam (Clarity, Pleasanton, CA) every 2 weeks. The fluorescein angiograms were examined to optimize the timing of diagnosis of ROP and to investigate development of retinal and choroidal vascularization. There were no side effects related to FA. Variable features of retinal and choroidal circulation in preterm infants with a high risk of developing ROP were noted. FA allows vessels branching at the junction between vascular and avascular retina (V-Av junction) to be viewed easily and shows the ROP findings that sometimes cannot be seen by indirect ophthalmoscopy. Dye leakage is the most significant sign of progression to severe ROP or the need for surgery in newborn babies with ROP. RetCam-assisted intravenous FA is safe and allows a more objective assessment of the ROP stage and zone.

  15. Low-level laser therapy improves vision in a patient with retinitis pigmentosa.

    Science.gov (United States)

    Ivandic, Boris T; Ivandic, Tomislav

    2014-03-01

    This case report describes the effects of low-level laser therapy (LLLT) in a single patient with retinitis pigmentosa (RP). RP is a heritable disorder of the retina, which eventually leads to blindness. No therapy is currently available. LLLT was applied using a continuous wave laser diode (780 nm, 10 mW average output at 292 Hz, 50% pulse modulation). The complete retina of eyes was irradiated through the conjunctiva for 40 sec (0.4 J, 0.333 W/cm2) two times per week for 2 weeks (1.6 J). A 55-year-old male patient with advanced RP was treated and followed for 7 years. The patient had complained of nyctalopia and decreasing vision. At first presentation, best visual acuity was 20/50 in each eye. Visual fields were reduced to a central residual of 5 degrees. Tritan-dyschromatopsy was found. Retinal potential was absent in electroretinography. Biomicroscopy showed optic nerve atrophy, and narrow retinal vessels with a typical pattern of retinal pigmentation. After four initial treatments of LLLT, visual acuity increased to 20/20 in each eye. Visual fields normalized except for a mid-peripheral absolute concentric scotoma. Five years after discontinuation of LLLT, a relapse was observed. LLLT was repeated (another four treatments) and restored the initial success. During the next 2 years, 17 additional treatments were performed on an "as needed" basis, to maintain the result. LLLT was shown to improve and maintain vision in a patient with RP, and may thereby have contributed to slowing down blindness.

  16. Healthy Lung Vessel Morphology Derived From Thoracic Computed Tomography

    Directory of Open Access Journals (Sweden)

    Michael Pienn

    2018-04-01

    Full Text Available Knowledge of the lung vessel morphology in healthy subjects is necessary to improve our understanding about the functional network of the lung and to recognize pathologic deviations beyond the normal inter-subject variation. Established values of normal lung morphology have been derived from necropsy material of only very few subjects. In order to determine morphologic readouts from a large number of healthy subjects, computed tomography pulmonary angiography (CTPA datasets, negative for pulmonary embolism, and other thoracic pathologies, were analyzed using a fully-automatic, in-house developed artery/vein separation algorithm. The number, volume, and tortuosity of the vessels in a diameter range between 2 and 10 mm were determined. Visual inspection of all datasets was used to exclude subjects with poor image quality or inadequate artery/vein separation from the analysis. Validation of the algorithm was performed manually by a radiologist on randomly selected subjects. In 123 subjects (men/women: 55/68, aged 59 ± 17 years, the median overlap between visual inspection and fully-automatic segmentation was 94.6% (69.2–99.9%. The median number of vessel segments in the ranges of 8–10, 6–8, 4–6, and 2–4 mm diameter was 9, 34, 134, and 797, respectively. Number of vessel segments divided by the subject's lung volume was 206 vessels/L with arteries and veins contributing almost equally. In women this vessel density was about 15% higher than in men. Median arterial and venous volumes were 1.52 and 1.54% of the lung volume, respectively. Tortuosity was best described with the sum-of-angles metric and was 142.1 rad/m (138.3–144.5 rad/m. In conclusion, our fully-automatic artery/vein separation algorithm provided reliable measures of pulmonary arteries and veins with respect to age and gender. There was a large variation between subjects in all readouts. No relevant dependence on age, gender, or vessel type was observed. These data may

  17. Molecular imaging reveals elevated VEGFR-2 expression in retinal capillaries in diabetes: a novel biomarker for early diagnosis

    OpenAIRE

    Sun, Dawei; Nakao, Shintaro; Xie, Fang; Zandi, Souska; Bagheri, Abouzar; Kanavi, Mozhgan Rezaei; Samiei, Shahram; Soheili, Zahra-Soheila; Frimmel, Sonja; Zhang, Zhongyu; Ablonczy, Zsolt; Ahmadieh, Hamid; Hafezi-Moghadam, Ali

    2014-01-01

    Diabetic retinopathy (DR) is a microvascular complication of diabetes and a leading cause of vision loss. Biomarkers and methods for early diagnosis of DR are urgently needed. Using a new molecular imaging approach, we show up to 94% higher accumulation of custom designed imaging probes against vascular endothelial growth factor receptor 2 (VEGFR-2) in retinal and choroidal vessels of diabetic animals (P

  18. Dynamic association between intraocular pressure and spontaneous pulsations of retinal veins.

    Science.gov (United States)

    Golzan, S Mojtaba; Graham, Stuart L; Leaney, John; Avolio, Alberto

    2011-01-01

    The amplitude of spontaneous retinal venous pulsations (SRVP) is known to be affected by intraocular pressure (IOP), retinal venous pressure, and intracranial pressure (ICP). This study characterized SRVPs adjacent to the disc and quantified changes in the amplitude of these pulsations during IOP manipulation in normal subjects. The study included 12 subjects (40 ± 15, 4 females, 8 males). Baseline IOP (range 10-25 mmHg) was measured and SRVP recorded using the dynamic retinal vessel analyzer (DVA). IOP was lowered using aproclonidine 0.5% and measured every 15 min, followed by dynamic recording of SRVP. Two subjects were also tested with timolol 0.5%, and three were treated with a placebo drop. Mean amplitude of SRVP was determined within each sample at the same site. Blood pressure and heart rate were tracked continuously. Amplitude of SRVP decreased in all subjects with reduction of IOP with aproclonidine and timolol. Mean SRVP amplitude was 8.5 ± 6 μm at baseline and reduced to 2.5 ± 1.8 μm after 45 min (p blood pressure, and heart rate did not change significantly from the baseline. Analysis of waveforms showed a slight phase shift only (150 ± 78.5 ms, p = 0.93) between disc veins and adjacent retinal vein. SRVPs in the peripapillary retina have similar waveform characteristics to those at the disc. SRVP amplitudes are reduced by manipulation of IOP downwards with pharmacological intervention. The relationship was consistent in all individuals tested for two classes of drugs and was independent of BP or heart rate changes.

  19. In-vessel coolability and steam explosion in Nordic BWRs

    International Nuclear Information System (INIS)

    Ma, W.; Hansson, R.; Li, L.; Kudinov, P.; Cadinu, F.; Tran, C-.T.

    2010-05-01

    The INCOSE project is to reduce the uncertainty in quantification of steam explosion risk and in-vessel coolability in Nordic BWR plants with the cavity flooding as a severe accident management (SAM) measure. During 2009 substantial advances and new insights into physical mechanisms were gained for studies of: (i) in-vessel corium coolability - development of the methodologies to assess the efficiency of the control rod guide tube (CRGT) cooling as a potential SAM measure; (ii) debris bed coolability - characterization of the effective particle diameter of multi-size particles and qualification of friction law for two-phase flow in the beds packed with multi-size particles; and (iii) steam explosion - investigation of the effect of binary oxides mixtures properties on steam explosion. An approach for coupling of ECM/PECM models with RELAP5 was developed to enhance predictive fidelity for melt pool heat transfer. MELCOR was employed to examine the CRGT cooling efficiency by considering an entire accident scenario, and the simulation results show that the nominal flowrate (∼10kg/s) of CRGT cooling is sufficient to maintain the integrity of the vessel in a BWR of 3900 MWth, if the water injection is activated no later than 1 hour after scram. The POMECO-FL experimental data suggest that for a particulate bed packed with multi-size particles, the effective particle diameter can be represented by the area mean diameter of the particles, while at high velocity (Re>7) the effective particle diameter is closer to the length mean diameter. The pressure drop of two-phase flow through the particulate bed can be predicted by Reed's model. The steam explosion experiments performed at high melt superheat (>200oC) using oxidic mixture of WO3-CaO didn't detect an apparent difference in steam explosion energetics and preconditioning between the eutectic and noneutectic melts. This points out that the next step of MISTEE experiment will be conducted at lower superheat. (author)

  20. A basic study on the ITER tritium storage vessel design and components

    International Nuclear Information System (INIS)

    Chung, H. S.; Ahn, D. H.; Kim, K. R.; Yim, S. P.; Paek, S. W.; Lee, M. S.; Lee, S. H.; Shim, M. H.

    2006-01-01

    The ZrCo getter beds are built of a primary vessel which contains the ZrCo powder mixed with Cu spheres of less than one mm diameter and of a secondary outer vessel. The purpose of the secondary outer vessel is to capture permeated or leaked tritium and to present a good thermal insulation when properly evacuated. A third volume, a helium filled loop, is installed in the primary volume to remove the decay heat and is used to perform tritium accountancy measurements

  1. Confinement Vessel Assay System: Calibration and Certification Report

    Energy Technology Data Exchange (ETDEWEB)

    Frame, Katherine C. [Los Alamos National Laboratory; Bourne, Mark M. [Los Alamos National Laboratory; Crooks, William J. [Los Alamos National Laboratory; Evans, Louise [Los Alamos National Laboratory; Gomez, Cipriano [Retired CMR-OPS: OPERATIONS; Mayo, Douglas R. [Los Alamos National Laboratory; Miko, David K. [Los Alamos National Laboratory; Salazar, William R. [Los Alamos National Laboratory; Stange, Sy [Los Alamos National Laboratory; Vigil, Georgiana M. [Los Alamos National Laboratory

    2012-07-17

    Los Alamos National Laboratory has a number of spherical confinement vessels (CVs) remaining from tests involving nuclear materials. These vessels have an inner diameter of 6 feet with 1 to 2 inch thick steel walls. The goal of the Confinement Vessel Disposition (CVD) project is to remove debris and reduce contamination inside the vessels. The Confinement Vessel Assay System (CVAS) was developed to measure the amount of SNM in CVs before and after cleanout. Prior to cleanout, the system will be used to perform a verification measurement of each vessel. After cleanout, the system will be used to perform safeguards-quality assays of {le} 100-g {sup 239}Pu equivalent in a vessel for safeguards termination. The system was calibrated in three different mass regions (low, medium, and high) to cover the entire plutonium mass range that will be assayed. The low mass calibration and medium mass calibration were verified for material positioned in the center of an empty vessel. The systematic uncertainty due to position bias was estimated using an MCNPX model to simulate the response of the system to material localized at various points along the inner surface of the vessel. The background component due to cosmic ray spallation was determined by performing measurements of an empty vessel and comparing to measurements in the same location with no vessel present. The CVAS has been tested and calibrated in preparation for verification and safeguards measurements of CVs before and after cleanout.

  2. Confinement Vessel Assay System: Calibration and Certification Report

    International Nuclear Information System (INIS)

    Frame, Katherine C.; Bourne, Mark M.; Crooks, William J.; Evans, Louise; Gomez, Cipriano; Mayo, Douglas R.; Miko, David K.; Salazar, William R.; Stange, Sy; Vigil, Georgiana M.

    2012-01-01

    Los Alamos National Laboratory has a number of spherical confinement vessels (CVs) remaining from tests involving nuclear materials. These vessels have an inner diameter of 6 feet with 1 to 2 inch thick steel walls. The goal of the Confinement Vessel Disposition (CVD) project is to remove debris and reduce contamination inside the vessels. The Confinement Vessel Assay System (CVAS) was developed to measure the amount of SNM in CVs before and after cleanout. Prior to cleanout, the system will be used to perform a verification measurement of each vessel. After cleanout, the system will be used to perform safeguards-quality assays of (le) 100-g 239 Pu equivalent in a vessel for safeguards termination. The system was calibrated in three different mass regions (low, medium, and high) to cover the entire plutonium mass range that will be assayed. The low mass calibration and medium mass calibration were verified for material positioned in the center of an empty vessel. The systematic uncertainty due to position bias was estimated using an MCNPX model to simulate the response of the system to material localized at various points along the inner surface of the vessel. The background component due to cosmic ray spallation was determined by performing measurements of an empty vessel and comparing to measurements in the same location with no vessel present. The CVAS has been tested and calibrated in preparation for verification and safeguards measurements of CVs before and after cleanout.

  3. Ex-vessel boiling experiments: laboratory- and reactor-scale testing of the flooded cavity concept for in-vessel core retention. Pt. II. Reactor-scale boiling experiments of the flooded cavity concept for in-vessel core retention

    International Nuclear Information System (INIS)

    Chu, T.Y.; Bentz, J.H.; Slezak, S.E.; Pasedag, W.F.

    1997-01-01

    For pt.I see ibid., p.77-88 (1997). This paper summarizes the results of a reactor-scale ex-vessel boiling experiment for assessing the flooded cavity design of the heavy water new production reactor. The simulated reactor vessel has a cylindrical diameter of 3.7 m and a torispherical bottom head. Boiling outside the reactor vessel was found to be subcooled nucleate boiling. The subcooling mainly results from the gravity head, which in turn results from flooding the side of the reactor vessel. The boiling process exhibits a cyclic pattern with four distinct phases: direct liquid-solid contact, bubble nucleation and growth, coalescence, and vapor mass dispersion. The results show that, under prototypic heat load and heat flux distributions, the flooded cavity will be effective for in-vessel core retention in the heavy water new production reactor. The results also demonstrate that the heat dissipation requirement for in-vessel core retention, for the central region of the lower head of an AP-600 advanced light water reactor, can be met with the flooded cavity design. (orig.)

  4. Inner Retinal Oxygen Extraction Fraction in Response to Light Flicker Stimulation in Humans

    Science.gov (United States)

    Felder, Anthony E.; Wanek, Justin; Blair, Norman P.; Shahidi, Mahnaz

    2015-01-01

    Purpose Light flicker has been shown to stimulate retinal neural activity, increase blood flow, and alter inner retinal oxygen metabolism (MO2) and delivery (DO2). The purpose of the study was to determine the change in MO2 relative to DO2 due to light flicker stimulation in humans, as assessed by the inner retinal oxygen extraction fraction (OEF). Methods An optical imaging system, based on a modified slit lamp biomicroscope, was developed for simultaneous measurements of retinal vascular diameter (D) and oxygen saturation (SO2). Retinal images were acquired in 20 healthy subjects before and during light flicker stimulation. Arterial and venous D (DA and DV) and SO2 (SO2A and SO2V) were quantified within a circumpapillary region. Oxygen extraction fraction was defined as the ratio of MO2 to DO2 and was calculated as (SO2A − SO2V)/SO2A. Reproducibility of measurements was assessed. Results Coefficients of variation and intraclass correlation coefficients of repeated measurements were <5% and ≥0.83, respectively. During light flicker stimulation, DA, DV , and SO2V significantly increased (P ≤ 0.004). Oxygen extraction fraction was 0.37 ± 0.08 before light flicker and significantly decreased to 0.31 ± 0.07 during light flicker (P = 0.001). Conclusions Oxygen extraction fraction before and during light flicker stimulation is reported in human subjects for the first time. Oxygen extraction fraction decreased during light flicker stimulation, indicating the change in DO2 exceeded that of MO2. This technology is potentially useful for the detection of changes in OEF response to light flicker in physiological and pathological retinal conditions. PMID:26469748

  5. Retinal oxygen saturation in relation to retinal thickness in diabetic macular edema

    DEFF Research Database (Denmark)

    Blindbæk, Søren Leer; Peto, Tunde; Grauslund, Jakob

    to retinal thickness in patients with diabetic macular edema (DME). Methods: We included 18 patients with DME that all had central retinal thickness (CRT) >300 µm and were free of active proliferative diabetic retinopathy. Optical coherence tomography (Topcon 3D OCT-2000 spectral domain OCT) was used...... for paracentral edema, the oxygen saturation in the upper and lower temporal arcade branches were compared to the corresponding upper and lower subfield thickness. Spearman’s rank was used to calculate correlation coefficients between CRT and retinal oximetry. Results: Median age and duration of diabetes was 59....... 92.3%, p=0.52). We found no correlation between CRT and retinal oxygen saturation, even when accounting for paracentral edema (p>0.05). Furthermore, there was no difference in retinal oxygen saturation between the macular hemisphere that was more or less affected by DME (p>0.05). Conclusion: Patients...

  6. Vessel wall reaction after vena cava filter placement

    NARCIS (Netherlands)

    Hoekstra, A; Elstrodt, JM; Nikkels, PGJ; Tiebosch, ATMG

    2002-01-01

    Purpose: To evaluate the interaction between the Cordis Keeper vena caval filter and vessel wall in a porcine model. Methods: Implantation of the filter was performed in five pigs. Radiologic data concerning inferior vena cava (IVC) diameter and filter patency, filter leg span, and stability were

  7. Noninvasive Retinal Markers in Diabetic Retinopathy

    DEFF Research Database (Denmark)

    Blindbæk, Søren Leer; Torp, Thomas Lee; Lundberg, Kristian

    2017-01-01

    The retinal vascular system is the only part of the human body available for direct, in vivo inspection. Noninvasive retinal markers are important to identity patients in risk of sight-threatening diabetic retinopathy. Studies have correlated structural features like retinal vascular caliber...... and fractals with micro- and macrovascular dysfunction in diabetes. Likewise, the retinal metabolism can be evaluated by retinal oximetry, and higher retinal venular oxygen saturation has been demonstrated in patients with diabetic retinopathy. So far, most studies have been cross-sectional, but these can only...... retinopathy and diabetic macular edema. The Department of Ophthalmology at Odense University Hospital, Denmark, has a strong tradition of studying the retinal microvasculature in diabetic retinopathy. In the present paper, we demonstrate the importance of the retinal vasculature not only as predictors of long...

  8. Frequency of lattice degeneration and retinal breaks in the fellow eye in retinal detachment.

    Science.gov (United States)

    Lorentzen, S E

    1988-04-01

    The fellow eye of 100 consecutively admitted cases of retinal detachment was studied with three-mirror examination for the presence of lattice degeneration and retinal breaks. Lattice degeneration was found in 18% and retinal breaks in 20% of fellow eyes.

  9. Imaging of pediatric great vessel stents: Computed tomography or magnetic resonance imaging?

    Directory of Open Access Journals (Sweden)

    A M den Harder

    Full Text Available Complications might occur after great vessel stent implantation in children. Therefore follow-up using imaging is warranted.To determine the optimal imaging modality for the assessment of stents used to treat great vessel obstructions in children.Five different large vessel stents were evaluated in an in-vitro setting. All stents were expanded to the maximal vendor recommended diameter (20mm; n = 4 or 10mm; n = 1, placed in an anthropomorphic chest phantom and imaged with a 256-slice CT-scanner. MRI images were acquired at 1.5T using a multi-slice T2-weighted turbo spin echo, an RF-spoiled three-dimensional T1-weighted Fast Field Echo and a balanced turbo field echo 3D sequence. Two blinded observers assessed stent lumen visibility (measured diameter/true diameter *100% in the center and at the outlets of the stent. Reproducibility of diameter measurements was evaluated using the intraclass correlation coefficient for reliability and 95% limits of agreement for agreement analysis.Median stent lumen visibility was 88 (IQR 86-90% with CT for all stents at both the center and outlets. With MRI, the T2-weighted turbo spin echo sequence was preferred which resulted in 82 (78-84% stent lumen visibility. Interobserver reliability and agreement was good for both CT (ICC 0.997, mean difference -0.51 [-1.07-0.05] mm and MRI measurements (ICC 0.951, mean difference -0.05 [-2.52 --2.41] mm.Good in-stent lumen visibility was achievable in this in-vitro study with both CT and MRI in different great vessel stents. Overall reliability was good with clinical acceptable limits of agreement for both CT and MRI. However, common conditions such as in-stent stenosis and associated aneurysms were not tested in this in-vitro study, limiting the value of the in-vitro study.

  10. Imaging of pediatric great vessel stents: Computed tomography or magnetic resonance imaging?

    Science.gov (United States)

    den Harder, A M; Suchá, D; van Hamersvelt, R W; Budde, R P J; de Jong, P A; Schilham, A M R; Bos, C; Breur, J M P J; Leiner, T

    2017-01-01

    Complications might occur after great vessel stent implantation in children. Therefore follow-up using imaging is warranted. To determine the optimal imaging modality for the assessment of stents used to treat great vessel obstructions in children. Five different large vessel stents were evaluated in an in-vitro setting. All stents were expanded to the maximal vendor recommended diameter (20mm; n = 4 or 10mm; n = 1), placed in an anthropomorphic chest phantom and imaged with a 256-slice CT-scanner. MRI images were acquired at 1.5T using a multi-slice T2-weighted turbo spin echo, an RF-spoiled three-dimensional T1-weighted Fast Field Echo and a balanced turbo field echo 3D sequence. Two blinded observers assessed stent lumen visibility (measured diameter/true diameter *100%) in the center and at the outlets of the stent. Reproducibility of diameter measurements was evaluated using the intraclass correlation coefficient for reliability and 95% limits of agreement for agreement analysis. Median stent lumen visibility was 88 (IQR 86-90)% with CT for all stents at both the center and outlets. With MRI, the T2-weighted turbo spin echo sequence was preferred which resulted in 82 (78-84%) stent lumen visibility. Interobserver reliability and agreement was good for both CT (ICC 0.997, mean difference -0.51 [-1.07-0.05] mm) and MRI measurements (ICC 0.951, mean difference -0.05 [-2.52 --2.41] mm). Good in-stent lumen visibility was achievable in this in-vitro study with both CT and MRI in different great vessel stents. Overall reliability was good with clinical acceptable limits of agreement for both CT and MRI. However, common conditions such as in-stent stenosis and associated aneurysms were not tested in this in-vitro study, limiting the value of the in-vitro study.

  11. Retinal Prosthesis System for Advanced Retinitis Pigmentosa: A Health Technology Assessment

    Science.gov (United States)

    Lee, Christine; Tu, Hong Anh; Weir, Mark; Holubowich, Corinne

    2016-01-01

    Background Retinitis pigmentosa is a group of genetic disorders that involves the breakdown and loss of photoreceptors in the retina, resulting in progressive retinal degeneration and eventual blindness. The Argus II Retinal Prosthesis System is the only currently available surgical implantable device approved by Health Canada. It has been shown to improve visual function in patients with severe visual loss from advanced retinitis pigmentosa. The objective of this analysis was to examine the clinical effectiveness, cost-effectiveness, budget impact, and safety of the Argus II system in improving visual function, as well as exploring patient experiences with the system. Methods We performed a systematic search of the literature for studies examining the effects of the Argus II retinal prosthesis system in patients with advanced retinitis pigmentosa, and appraised the evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group criteria, focusing on visual function, functional outcomes, quality of life, and adverse events. We developed a Markov decision-analytic model to assess the cost-effectiveness of the Argus II system compared with standard care over a 10-year time horizon. We also conducted a 5-year budget impact analysis. We used a qualitative design and an interview methodology to examine patients’ lived experience, and we used a modified grounded theory methodology to analyze information from interviews. Transcripts were coded, and themes were compared against one another. Results One multicentre international study and one single-centre study were included in the clinical review. In both studies, patients showed improved visual function with the Argus II system. However, the sight-threatening surgical complication rate was substantial. In the base-case analysis, the Argus II system was cost-effective compared with standard care only if willingness-to-pay was more than $207,616 per quality-adjusted life

  12. Raised intraocular pressure and recurrence of retinal detachment as complications of external retinal detachment surgery

    International Nuclear Information System (INIS)

    Jawwad, M.; Khan, B.; Shah, M.A.; Qayyum, I.; Aftab, M.; Qayyum, I.

    2015-01-01

    Patients with Rhegmatogenous retinal detachment may develop raised intraocular pressure and recurrence of retinal detachment when they undergo external retinal detachment surgery. The present study was conducted to determine the postoperative rise in intraocular pressure (IOP) and recurrence of retinal detachment. Methods: The present descriptive study was conducted at Eye department of Lady Reading Hospital, Peshawar on 25 patients of both genders from August 2012 to July 2014. Results: Of the 25 patients, 18 (72%) developed raised IOP in the immediate postoperative period; this figure decreased to 12 (48%) at one week. Following medical or surgical intervention in these 12 cases, there was only 1 (4%) case with mildly raised IOP at two weeks postoperative. Five (20%) cases developed recurrent retinal detachment which later resolved with treatment. There were no significant differences by age or gender. Conclusion: External Retinal Detachment Surgery raised intraocular pressure postoperatively and caused recurrence of retinal detachment. These complications were treated medically and surgically with resolution within two weeks. (author)

  13. Peripheral Retinal Vascular Patterns in Patients with Rhegmatogenous Retinal Detachment in Taiwan

    Science.gov (United States)

    Chen, San-Ni; Hwang, Jiunn-Feng; Wu, Wen-Chuan

    2016-01-01

    This is an observational study of fluorescein angiography (FA) in consecutive patients with rhegmatogenous retinal detachment (RRD) in Changhua Christian Hospital to investigate the peripheral retinal vascular patterns in those patients. All patients had their age, sex, axial length (AXL), and refraction status (RF) recorded. According to the findings in FA of the peripheral retina, the eyes were divided into 4 groups: in group 1, there was a ramified pattern of peripheral retinal vasculature with gradual tapering; in group 2, there was an abrupt ending of peripheral vasculature with peripheral non-perfusion; in group 3, there was a curving route of peripheral vasculature forming vascular arcades or anastomosis; and in group 4, the same as in group 3, but with one or more wedge-shaped avascular notches. Comparisons of age, sex, AXL, and RF, association of breaks with lattice degeneration and retinal non-perfusion, surgical procedures utilized, and mean numbers of operations were made among the four groups. Of the 73 eyes studied, there were 13 eyes (17.8%) in group 1, 3 eyes (4.1%) in group 2, 40 eyes (54.8%) in group 3 and 17 eyes (23.3%) in group 4. Significant differences in age, AXL and RF, and association of retinal breaks to non-perfusion were noted among the four groups. Patients in group 1 had older ages, while younger ages were noted in groups 3 and 4. Eyes in group 1 had the shortest average AXL and were least myopic in contrast to the eyes in groups 3 and 4. Association of retinal breaks and retinal non-perfusion was significantly higher in groups 2, 3 and 4 than in group 1. In conclusion, peripheral vascular anomalies are common in cases with RRD. Patients with peripheral non-perfusion tend to be younger, with longer axial length and have the breaks associated with retinal non-perfusion. PMID:26909812

  14. Nuclear reactor construction with bottom supported reactor vessel

    International Nuclear Information System (INIS)

    Sharbaugh, J.E.

    1987-01-01

    This patent describes an improved liquid metal nuclear reactor construction comprising: (a) a nuclear reactor core having a bottom platform support structure; (b) a reactor vessel for holding a large pool of low pressure liquid metal coolant and housing the core; (c) a containment structure surrounding the reactor vessel and having a sidewall spaced outwardly from the reactor vessel side wall and having a base mat spaced below the reactor vessel bottom end wall; (d) a central small diameter post anchored to the containment structure base mat and extending upwardly to the reactor vessel to axially fix the bottom end wall of the reactor vessel and provide a center column support for the lower end of the reactor core; (e) annular support structure disposed in the reactor vessel on the bottom end wall and extending about the lower end of the core; (f) structural support means disposed between the containment structure base mat and bottom end of the reactor vessel wall and cooperating for supporting the reactor vessel at its bottom end wall on the containment structure base mat to allow the reactor vessel to expand radially but substantially prevent any lateral motions that might be imposed by the occurrence of a seismic event; (g) a bed of insulating material disposed between the containment structure base mat and the bottom end wall of the reactor vessel and uniformly supporting the reactor vessel at its bottom end wall; freely expand radially from the central post as it heats up while providing continuous support thereof; (h) a deck supported upon the wall of the containment vessel above the top open end of the reactor vessel; and (i) extendible and retractable coupling means extending between the deck and the top open end of the reactor vessel and flexibly and sealably interconnecting the reactor vessel at its top end to the deck

  15. Vacuum vessels for the LHC magnets arrive at CERN

    CERN Multimedia

    2001-01-01

    The first batch of pre-series vacuum vessels for the LHC dipole magnets has just been delivered to CERN. The vessels are components of the cryostats and will provide the thermal insulation for the superconducting magnets. The first batch of vacuum vessels for the LHC dipole magnets with the team taking part at CERN in ordering and installing them. Left to right : Claude Hauviller, Monique Dupont, Lloyd Williams, Franck Gavin, Alain Jacob, Christophe Vuitton, Davide Bozzini, Laure Sandri, Mikael Sjoholm and André de Saever. In 2006 all that will be seen of the LHC superconducting dipoles in the LHC tunnel will be a line of over 1230 blue cylindrical vacuum vessels. Ten vessels, each weighing 4 tonnes, are already at CERN. On 6 July the first batch of pre-series vessels reached the Lab-oratory from the firm SIMIC Spa whose works are near Savona in north-western Italy. Despite appearances, these 15-metre long, 1-metre diameter blue tubes are much more sophisticated than sections of a run-of-the-mill...

  16. Investigation of retinal morphology alterations using spectral domain optical coherence tomography in a mouse model of retinal branch and central retinal vein occlusion.

    Directory of Open Access Journals (Sweden)

    Andreas Ebneter

    Full Text Available Retinal vein occlusion is a leading cause of visual impairment. Experimental models of this condition based on laser photocoagulation of retinal veins have been described and extensively exploited in mammals and larger rodents such as the rat. However, few reports exist on the use of this paradigm in the mouse. The objective of this study was to investigate a model of branch and central retinal vein occlusion in the mouse and characterize in vivo longitudinal retinal morphology alterations using spectral domain optical coherence tomography. Retinal veins were experimentally occluded using laser photocoagulation after intravenous application of Rose Bengal, a photo-activator dye enhancing thrombus formation. Depending on the number of veins occluded, variable amounts of capillary dropout were seen on fluorescein angiography. Vascular endothelial growth factor levels were markedly elevated early and peaked at day one. Retinal thickness measurements with spectral domain optical coherence tomography showed significant swelling (p<0.001 compared to baseline, followed by gradual thinning plateauing two weeks after the experimental intervention (p<0.001. Histological findings at day seven correlated with spectral domain optical coherence tomography imaging. The inner layers were predominantly affected by degeneration with the outer nuclear layer and the photoreceptor outer segments largely preserved. The application of this retinal vein occlusion model in the mouse carries several advantages over its use in other larger species, such as access to a vast range of genetically modified animals. Retinal changes after experimental retinal vein occlusion in this mouse model can be non-invasively quantified by spectral domain optical coherence tomography, and may be used to monitor effects of potential therapeutic interventions.

  17. Drug-eluting stents appear superior to bare metal stents for vein-graft PCI in vessels up to a stent diameter of 4 mm

    Directory of Open Access Journals (Sweden)

    Oliver P. Guttmann

    2016-05-01

    Full Text Available BackgroundResearch trials have shown improved short-term outcome with drug-eluting stents (DES over bare metal stents (BMS in saphenous vein graft (SVG percutaneous coronary intervention (PCI, primarily by reducing target vessel revascularization (TVR for in-stent restenosis. We compared the outcomes in patients undergoing SVG stent implantation treated with DES or BMS. In exploratory analyses we investigated the influence of stent generation and diameter.MethodsData were obtained from a prospective database of 657 patients who underwent PCI for SVG lesions between 2003 and 2011. A total of 344 patients had PCI with BMS and 313 with DES. Propensity scores were developed based on 15 observed baseline covariates in a logistic regression model with stent type as the dependent variable. The nearest-neighbour-matching algorithm with Greedy 5-1 Digit Matching was used to produce two patient cohorts of 313 patients each. We assessed major adverse cardiac events (MACE out to a median of 3.3 years (interquartile range: 2.1-4.1. MACE was defined as all-cause mortality, myocardial infarction (MI, TVR and stroke.ResultsThere was a significant difference in MACE between the two groups in favour of DES (17.9% DES vs. 31.2% BMS group; p = 0.0017 over the 5-year follow-up period. MACE was driven by increased TVR in the BMS group. There was no difference in death, MI or stroke. Adjusted Cox analysis confirmed a decreased risk of MACE for DES compared with BMS 0.75 (95% confidence interval (CI 0.52-0.94, with no difference in the hazard of all-cause mortality (hazard ratio: 1.08; 95% CI: 0.77-1.68. However, when looking at stent diameters greater than 4 mm, no difference was seen in MACE rates between BMS and DES.ConclusionsOverall in our cohort of patients who had PCI for SVG disease, DES use resulted in lower MACE rates compared with BMS over a 5-year follow-up period; however, for stent diameters over 4 mm no difference in MACE rates was seen.

  18. Heavy wall pressure vessels for energy systems

    International Nuclear Information System (INIS)

    Canonico, D.A.

    Modifications of steels currently accepted in the Code appear to provide improved mechanical properties. These steels may permit the fabrication of larger diameter vessels with thinner section sizes and improved reliability and integrity. Adapting current specifications should expedite Code approval. Finally the challenge of improving welding procedures and adapting processes for field applications will result in higher quality weldments

  19. Retinal Imaging and Image Analysis

    Science.gov (United States)

    Abràmoff, Michael D.; Garvin, Mona K.; Sonka, Milan

    2011-01-01

    Many important eye diseases as well as systemic diseases manifest themselves in the retina. While a number of other anatomical structures contribute to the process of vision, this review focuses on retinal imaging and image analysis. Following a brief overview of the most prevalent causes of blindness in the industrialized world that includes age-related macular degeneration, diabetic retinopathy, and glaucoma, the review is devoted to retinal imaging and image analysis methods and their clinical implications. Methods for 2-D fundus imaging and techniques for 3-D optical coherence tomography (OCT) imaging are reviewed. Special attention is given to quantitative techniques for analysis of fundus photographs with a focus on clinically relevant assessment of retinal vasculature, identification of retinal lesions, assessment of optic nerve head (ONH) shape, building retinal atlases, and to automated methods for population screening for retinal diseases. A separate section is devoted to 3-D analysis of OCT images, describing methods for segmentation and analysis of retinal layers, retinal vasculature, and 2-D/3-D detection of symptomatic exudate-associated derangements, as well as to OCT-based analysis of ONH morphology and shape. Throughout the paper, aspects of image acquisition, image analysis, and clinical relevance are treated together considering their mutually interlinked relationships. PMID:22275207

  20. [Peripheral retinal degenerations--treatment recommendations].

    Science.gov (United States)

    Joussen, A M; Kirchhof, B

    2004-10-01

    This report reviews the clinical appearance of degenerative diseases of the peripheral retina in relationship to the risk of developing a rhegmatogenous retinal detachment. We present recommendations for preventive treatment in eyes at increased risk of developing retinal detachment. Retinal degenerations are common lesions involving the peripheral retina but most of them are clinically insignificant. Lattice degeneration, degenerative retinoschisis, cystic retinal tufts, and very rarely zonular traction tufts can result in rhegmatogenous retinal detachment. Therefore, these lesions have been considered for prophylactic treatment; however, adequate studies have not been performed to date. Most of the peripheral retinal degenerations may not require treatment except in rare, high-risk situations. According to current knowledge there is no higher incidence of secondary pucker or other side effects after laser coagulation. Therefore, generous laser indication is recommended if risk factors apply.

  1. Multimodal quantitation of the effects of endovascular therapy for vasospasm on cerebral blood flow, transcranial doppler ultrasonographic velocities, and cerebral artery diameters.

    Science.gov (United States)

    Oskouian, Rod J; Martin, Neil A; Lee, Jae Hong; Glenn, Thomas C; Guthrie, Donald; Gonzalez, Nestor R; Afari, Arash; Viñuela, Fernando

    2002-07-01

    The goal of this study was to quantify the effects of endovascular therapy on vasospastic cerebral vessels. We reviewed the medical records for 387 patients with ruptured intracranial aneurysms who were treated at a single institution (University of California, Los Angeles) between May 1, 1993, and March 31, 2001. Patients who developed cerebral vasospasm and underwent cerebral arteriographic, transcranial Doppler ultrasonographic, and cerebral blood flow (CBF) studies before and after endovascular therapy for cerebral arterial spasm (vasospasm) were included in this study. Forty-five patients fulfilled the aforementioned criteria and were treated with either papaverine infusion, papaverine infusion with angioplasty, or angioplasty alone. After balloon angioplasty (12 patients), CBF increased from 27.8 +/- 2.8 ml/100 g/min to 28.4 +/- 3.0 ml/100 g/min (P = 0.87); the middle cerebral artery blood flow velocity was 1 57.6 +/- 9.4 cm/s and decreased to 76.3 +/- 9.3 cm/s (P < 0.05), with a mean increase in cerebral artery diameters of 24.4%. Papaverine infusion (20 patients) transiently increased the CBF from 27.5 +/- 2.1 ml/100 g/min to 38.7 +/- 2.8 ml/100 g/min (P < 0.05) and decreased the middle cerebral artery blood flow velocity from 109.9 +/- 9.1 cm/s to 82.8 +/- 8.6 cm/s (P < 0.05). There was a mean increase in vessel diameters of 30.1% after papaverine infusion. Combined treatment (13 patients) significantly increased the CBF from 33.3 +/- 3.2 ml/100 g/min to 41.7 +/- 2.8 ml/100 g/min (P< 0.05) and decreased the transcranial Doppler velocities from 148.9 +/- 12.7 cm/s to 111.4 +/- 10.6 cm/s (P < 0.05), with a mean increase in vessel diameters of 42.2%. Balloon angioplasty increased proximal vessel diameters, whereas papaverine treatment effectively dilated distal cerebral vessels. In our small series, we observed no correlation between early clinical improvement or clinical outcomes and any of our quantitative or physiological data (CBF, transcranial Doppler

  2. Relationships among Ocular Blood Flow Shown by Laser Speckle Flowgraphy, Retinal Arteriosclerotic Change, and Chorioretinal Circulation Time Obtained by Fluorescein Angiography

    Directory of Open Access Journals (Sweden)

    Hironori Osamura

    2017-01-01

    Full Text Available Purpose. To determine the correlations among the mean blur rate (MBR in the optic nerve head (ONH shown by laser speckle flowgraphy (LSFG, retinal arteriosclerosis, and the circulation time obtained by fluorescein angiography (FA. Method. We evaluated 118 patients and assessed their time of choroidal flush, arm-to-retina time, and early and late phases of retinal circulation time (RT: sec obtained by FA. The severity of retinal arteriosclerosis was classified according to the Scheie classification. The MBR values throughout the ONH (MBR-A, in the tissue (MBR-T, and in the vessels (MBR-V were analyzed. Results. Patients with retinal vein occlusion (RVO showed prolonged early and late phases of RT compared to other ocular diseases. Single and multiple regression analyses showed that the MBR-V and Scheie classification were significantly associated with both the choroidal flush and arm-to-retina times. The incidences of RVO and MVR-V were significantly associated with the early phase of RT, and the incidences of RVO, MBR-V, Scheie classification, and gender were revealed to be factors independently contributing to the late phase of RT. Conclusion. MBR-V in the ONH and retinal arteriosclerosis are important contributing factors for the circulation time of each stage obtained by FA.

  3. Risk factor profile in retinal detachment

    Directory of Open Access Journals (Sweden)

    Azad Raj

    1988-01-01

    Full Text Available 150 cases of retinal detachment comprising 50 patients each of bilateral retinal detachment, unilateral retinal detachment without any retinal lesions in the fellow eve and unilateral retinal detachment with retinal lesions in the fellow eye were studied and the various associated risk factors were statistically analysed. The findings are discussed in relation to their aetiological and prognostic significance in the different types of retinal detachment. Based on these observations certain guidelines are offered which may be of value in decision making, in prophylactic detachment surgery. Tractional breaks in the superior temporal quadrant especially when symptomatic. mandate prophylactic treatment. Urgency is enhanced it′ the patient is aphakic. Associated myopia adds to the urgency. The higher incidence of initial right e′ e involvement in all groups suggests a vascular original possibly ischaemic.

  4. Cytomegalovirus retinitis after central retinal vein occlusion in a patient on systemic immunosuppression: does venooclusive disease predispose to cytomegalovirus retinitis in patients already at risk?

    Directory of Open Access Journals (Sweden)

    Welling JD

    2012-04-01

    Full Text Available John D Welling, Ahmad B Tarabishy, John ChristoforidisDepartment of Ophthalmology, Havener Eye Institute, Ohio State University, Columbus, OH, USAAbstract: Cytomegalovirus (CMV retinitis remains the most common opportunistic ocular infection in immunocompromised patients. Patients with immunocompromising diseases, such as acquired immunodeficiency syndrome, inherited immunodeficiency states, malignancies, and those on systemic immunosuppressive therapy, are known to be at risk. Recently, it has been suggested that patients undergoing intravitreal injection of immunosuppressive agents may also be predisposed. One previous case report speculated that there may be an additional risk for CMV retinitis in acquired immunodeficiency syndrome patients with venoocclusive disease. This case study presents a case of CMV retinitis following central retinal vein occlusion in a patient on systemic immunosuppressants.Keywords: cytomegalovirus retinitis, central retinal vein occlusion, immunosuppression, solid organ transplant, venous stasis, risk factor

  5. WIDEFIELD SPECTRAL-DOMAIN OPTICAL COHERENCE TOMOGRAPHY IMAGING OF PERIPHERAL ROUND RETINAL HOLES WITH OR WITHOUT RETINAL DETACHMENT.

    Science.gov (United States)

    Casswell, Edward J; Abou Ltaif, Sleiman; Carr, Thomas; Keane, Pearse A; Charteris, David G; Wickham, Louisa

    2018-03-02

    To describe the widefield spectral-domain optical coherence tomography features of peripheral round retinal holes, with or without associated retinal detachment (RD). Retrospective, observational study of 28 eyes with peripheral round retinal holes, with and without RD. Patients underwent imaging with a widefield 50-degree spectral-domain optical coherence tomography (Heidelberg Engineering, Germany) and Optos ultra-widefield imaging systems (Optos, United Kingdom). Vitreous attachment at the site of the retinal hole was detected in 27/28 (96.4%) cases. Cases were split into three groups: RHs with RD (n = 12); RHs with subretinal fluid (n = 5), and flat RHs (n = 11), with minimal or no subretinal fluid. 91.6% retinal holes associated with subretinal fluid or RD had vitreous attachment at the site of the hole. Eighty percent had vitreous attachment at both edges of the retinal hole, in a U-shape configuration, which appeared to exert traction. By contrast, flat retinal holes had visible vitreous attachment only at one edge of the retinal hole in 45.4%. Vitreous attachment was commonly seen at the site of round retinal holes. Vitreous attachment at both edges of the retinal hole in a U-shape configuration was more commonly seen at holes associated with subretinal fluid or RD.

  6. The behaviour of the pulmonary vessels on X-ray films of children with asthma bronchiale

    International Nuclear Information System (INIS)

    Hegenbarth, R.; Toeroek, M.; Medizinische Hochschule Hannover

    1986-01-01

    On X-ray films of 51 children with asthma bronchiale the authors determined the vascular diameter of the right ascending pulmonary artery, the right vein of the upper lobe, and the peripheral vessels in the upper and lower pulmonary fields at an exactly defined distance from the hilus point, and compared these data with those of a control group of 143 healthy children. During the asthma attack the width of the right descending pulmonary artery and of the vein of the upper lobe corresponded to the values of the control group, whereas the vascular diameters in the upper and lower fields were clearly narrowed. Moreover, in most of the asthmatic children the authors found arc-shaped vessels and irregularly occluded vessels in the periphery of the lungs. (orig.) [de

  7. Retinal detachment following endophthalmitis.

    Science.gov (United States)

    Nelsen, P T; Marcus, D A; Bovino, J A

    1985-08-01

    Fifty-five consecutive patients with a clinical diagnosis of bacterial endophthalmitis were reviewed. All patients were treated with systemic, periocular, topical, and intravitreal antibiotics. In addition, 33 of the patients underwent a pars plana vitrectomy. Nine retinal detachments occurred within six months of initial diagnosis. The higher frequency of retinal detachment in the vitrectomy group (21%) as compared to those patients managed without vitrectomy (9%) may be explained by a combination of surgical complications and the increased severity of endophthalmitis in the vitrectomy group. The two patients who developed retinal detachment during vitrectomy surgery rapidly progressed to no light perception. Conversely, the repair of retinal detachments diagnosed postoperatively had a good prognosis.

  8. Effect of pharmacologically induced retinal degeneration on retinal autofluorescence lifetimes in mice.

    Science.gov (United States)

    Dysli, Chantal; Dysli, Muriel; Zinkernagel, Martin S; Enzmann, Volker

    2016-12-01

    Fluorescence lifetime imaging ophthalmoscopy (FLIO) was used to investigate retinal autofluorescence lifetimes in mouse models of pharmacologically induced retinal degeneration over time. Sodium iodate (NaIO 3 , 35 mg/kg intravenously) was used to induce retinal pigment epithelium (RPE) degeneration with subsequent loss of photoreceptors (PR) whereas N-methyl-N-nitrosourea (MNU, 45 mg/kg intraperitoneally) was employed for degeneration of the photoreceptor cell layer alone. All mice were measured at day 3, 7, 14, and 28 after the respective injection of NaIO 3 , MNU or NaCl (control). Fluorescence lifetime imaging was performed using a fluorescence lifetime imaging ophthalmoscope (Heidelberg Engineering, Heidelberg, Germany). Fluorescence was excited at 473 nm and fluorescence lifetimes were measured in a short and a long spectral channel (498-560 nm and 560-720 nm). Corresponding optical coherence tomography (OCT) images were consecutively acquired and histology was performed at the end of the experiments. Segmentation of OCT images and histology verified the cell type-specific degeneration process over time. Retinal autofluorescence lifetimes increased from day 3 to day 28 in mice after NaIO 3 treatment. Finally, at day 28, fluorescence lifetimes were prolonged by 8% in the short and 61% in the long spectral channel compared to control animals (p = 0.21 and p = 0.004, respectively). In mice after MNU treatment, the mean retinal autofluorescence lifetimes were already decreased at day 3 and retinal lifetimes were finally shortened by 27% in the short and 51% in the long spectral channel at day 28 (p = 0.0028). In conclusion, degeneration of the RPE with subsequent photoreceptor degeneration by NaIO 3 lead to longer mean fluorescence lifetimes of the retina compared to control mice, whereas during specific degeneration of the photoreceptor layer induced by MNU shorter lifetimes were measured. Therefore, short retinal fluorescence lifetimes may originate

  9. Peripheral Retinal Vascular Patterns in Patients with Rhegmatogenous Retinal Detachment in Taiwan.

    Directory of Open Access Journals (Sweden)

    San-Ni Chen

    Full Text Available This is an observational study of fluorescein angiography (FA in consecutive patients with rhegmatogenous retinal detachment (RRD in Changhua Christian Hospital to investigate the peripheral retinal vascular patterns in those patients. All patients had their age, sex, axial length (AXL, and refraction status (RF recorded. According to the findings in FA of the peripheral retina, the eyes were divided into 4 groups: in group 1, there was a ramified pattern of peripheral retinal vasculature with gradual tapering; in group 2, there was an abrupt ending of peripheral vasculature with peripheral non-perfusion; in group 3, there was a curving route of peripheral vasculature forming vascular arcades or anastomosis; and in group 4, the same as in group 3, but with one or more wedge-shaped avascular notches. Comparisons of age, sex, AXL, and RF, association of breaks with lattice degeneration and retinal non-perfusion, surgical procedures utilized, and mean numbers of operations were made among the four groups. Of the 73 eyes studied, there were 13 eyes (17.8% in group 1, 3 eyes (4.1% in group 2, 40 eyes (54.8% in group 3 and 17 eyes (23.3% in group 4. Significant differences in age, AXL and RF, and association of retinal breaks to non-perfusion were noted among the four groups. Patients in group 1 had older ages, while younger ages were noted in groups 3 and 4. Eyes in group 1 had the shortest average AXL and were least myopic in contrast to the eyes in groups 3 and 4. Association of retinal breaks and retinal non-perfusion was significantly higher in groups 2, 3 and 4 than in group 1. In conclusion, peripheral vascular anomalies are common in cases with RRD. Patients with peripheral non-perfusion tend to be younger, with longer axial length and have the breaks associated with retinal non-perfusion.

  10. Proof testing of an explosion containment vessel

    Energy Technology Data Exchange (ETDEWEB)

    Esparza, E.D. [Esparza (Edward D.), San Antonio, TX (United States); Stacy, H.; Wackerle, J. [Los Alamos National Lab., NM (United States)

    1996-10-01

    A steel containment vessel was fabricated and proof tested for use by the Los Alamos National Laboratory at their M-9 facility. The HY-100 steel vessel was designed to provide total containment for high explosives tests up to 22 lb (10 kg) of TNT equivalent. The vessel was fabricated from an 11.5-ft diameter cylindrical shell, 1.5 in thick, and 2:1 elliptical ends, 2 in thick. Prior to delivery and acceptance, three types of tests were required for proof testing the vessel: a hydrostatic pressure test, air leak tests, and two full design charge explosion tests. The hydrostatic pressure test provided an initial static check on the capacity of the vessel and functioning of the strain instrumentation. The pneumatic air leak tests were performed before, in between, and after the explosion tests. After three smaller preliminary charge tests, the full design charge weight explosion tests demonstrated that no yielding occurred in the vessel at its rated capacity. The blast pressures generated by the explosions and the dynamic response of the vessel were measured and recorded with 33 strain channels, 4 blast pressure channels, 2 gas pressure channels, and 3 displacement channels. This paper presents an overview of the test program, a short summary of the methodology used to predict the design blast loads, a brief description of the transducer locations and measurement systems, some of the hydrostatic test strain and stress results, examples of the explosion pressure and dynamic strain data, and some comparisons of the measured data with the design loads and stresses on the vessel.

  11. Ecomorphology of eye shape and retinal topography in waterfowl (Aves: Anseriformes: Anatidae) with different foraging modes.

    Science.gov (United States)

    Lisney, Thomas J; Stecyk, Karyn; Kolominsky, Jeffrey; Schmidt, Brian K; Corfield, Jeremy R; Iwaniuk, Andrew N; Wylie, Douglas R

    2013-05-01

    Despite the large body of literature on ecomorphological adaptations to foraging in waterfowl, little attention has been paid to their sensory systems, especially vision. Here, we compare eye shape and retinal topography across 12 species representing 4 different foraging modes. Eye shape was significantly different among foraging modes, with diving and pursuit-diving species having relatively smaller corneal diameters compared to non-diving species. This may be associated with differences in ambient light intensity while foraging or an ability to tightly constrict the pupil in divers in order to facilitate underwater vision. Retinal topography was similar across all species, consisting of an oblique visual streak, a central area of peak cell density, and no discernible fovea. Because the bill faces downwards when the head is held in the normal posture in waterfowl, the visual streak will be held horizontally, allowing the horizon to be sampled with higher visual acuity. Estimates of spatial resolving power were similar among species with only the Canada goose having a higher spatial resolution. Overall, we found no evidence of ecomorphological adaptations to different foraging modes in the retinal ganglion cell layer in waterfowl. Rather, retinal topography in these birds seems to reflect the 'openness' of their habitats.

  12. Depiction of blood vessels by x-ray phase contrast

    Energy Technology Data Exchange (ETDEWEB)

    Momose, Atsushi [School of Engineering, University of Tokyo, Tokyo (Japan); Takeda, Tohoru; Itai, Yuji [Institute of Clinical Medicine, University of Tsukuba, Tsukuba, Ibaraki (Japan)

    2001-04-01

    Blood vessels in livers of a mouse and a rat were depicted by phase-contrast x-ray imaging with an x-ray interferometer without using contrast agents. X-ray interference patterns were converted to image mapping x-ray phase shift caused by the livers using the technique of phase-shifting x-ray interferometry. The arteries and veins to and from the livers were tied before excision in order to prevent blood from flowing out of the liver. The x-ray phase shift caused by blood was substantially different from that caused by other soft sues, and consequently trees of blood vessels were revealed in the images. Vessels of diameter smaller than 0.1 mm were detected. This result suggests new possibilities for investigating vascular systems. (author)

  13. Advances in Retinal Stem Cell Biology

    Directory of Open Access Journals (Sweden)

    Andrea S Viczian

    2013-01-01

    Full Text Available Tremendous progress has been made in recent years to generate retinal cells from pluripotent cell sources. These advances provide hope for those suffering from blindness due to lost retinal cells. Understanding the intrinsic genetic network in model organisms, like fly and frog, has led to a better understanding of the extrinsic signaling pathways necessary for retinal progenitor cell formation in mouse and human cell cultures. This review focuses on the culture methods used by different groups, which has culminated in the generation of laminated retinal tissue from both embryonic and induced pluripotent cells. The review also briefly describes advances made in transplantation studies using donor retinal progenitor and cultured retinal cells.

  14. Sector retinitis pigmentosa.

    Science.gov (United States)

    Van Woerkom, Craig; Ferrucci, Steven

    2005-05-01

    Retinitis pigmentosa (RP) is one of the most common hereditary retinal dystrophies and causes of visual impairment affecting all age groups. The reported incidence varies, but is considered to be between 1 in 3,000 to 1 in 7,000. Sector retinitis pigmentosa is an atypical form of RP that is characterized by regionalized areas of bone spicule pigmentation, usually in the inferior quadrants of the retina. A 57-year-old Hispanic man with a history of previously diagnosed retinitis pigmentosa came to the clinic with a longstanding symptom of decreased vision at night. Bone spicule pigmentation was found in the nasal and inferior quadrants in each eye. He demonstrated superior and temporal visual-field loss corresponding to the areas of the affected retina. Clinical measurements of visual-field loss, best-corrected visual acuity, and ophthalmoscopic appearance have remained stable during the five years the patient has been followed. Sector retinitis pigmentosa is an atypical form of RP that is characterized by bilateral pigmentary retinopathy, usually isolated to the inferior quadrants. The remainder of the retina appears clinically normal, although studies have found functional abnormalities in these areas as well. Sector RP is generally considered a stationary to slowly progressive disease, with subnormal electro-retinogram findings and visual-field defects corresponding to the involved retinal sectors. Management of RP is very difficult because there are no proven methods of treatment. Studies have shown 15,000 IU of vitamin A palmitate per day may slow the progression, though this result is controversial. Low vision rehabilitation, long wavelength pass filters, and pedigree counseling remain the mainstay of management.

  15. An 810 ft/sec soil impact test of a 2-foot diameter model nuclear reactor containment system

    Science.gov (United States)

    Puthoff, R. L.

    1972-01-01

    A soil impact test was conducted on a 880-pound 2-foot diameter sphere model. The impact area consisted of back filled desert earth and rock. The impact generated a crater 5 feet in diameter by 5 feet deep. It buried itself a total of 15 feet - as measured to the bottom of the model. After impact the containment vessel was pressure checked. No leaks were detected nor cracks observed.

  16. Cone dysfunctions in retinitis pigmentosa with retinal nerve fiber layer thickening.

    Science.gov (United States)

    Sobacı, Güngör; Ozge, Gökhan; Gündoğan, Fatih Ç

    2012-01-01

    To investigate whether or not thicker retinal nerve fiber layer (RNFL) in retinitis pigmentosa (RP) patients relates to functional abnormalities of the photoreceptors. Optical coherence tomography-based RNFL thickness was measured by Stratus-3™ (Zeiss, Basel, Switzerland) optical coherence tomography and electroretinogram (ERG) recordings made using the RETI-port(®) system (Roland, Wiesbaden, Germany) in 27 patients with retinitis pigmentosa and in 30 healthy subjects. Photopic ERG b-wave amplitude, cone ERG b-wave latency, 30 Hz flicker amplitude, and 30 Hz flicker latency had significant correlations to the RNFL-temporal (r = -0.55, P = 0.004, r = 0.68, P = 0.001, r = -0.65, P = 0.001, and r = -0.52, P = 0.007, respectively). Eyes with thicker RNFL (ten eyes) differed significantly from those with thinner RNFL (eight eyes) regarding cone ERG b-wave latency values only (P = 0.001). Thicker RNFL in patients with retinitis pigmentosa may be associated with functional abnormality of the cone system.

  17. Progressive outer retinal necrosis (PORN) in AIDS patients: a different appearance of varicella-zoster retinitis.

    Science.gov (United States)

    Pavesio, C E; Mitchell, S M; Barton, K; Schwartz, S D; Towler, H M; Lightman, S

    1995-01-01

    Retinal infections caused by the varicella-zoster virus (VZV) have been reported in immunocompetent and immunocompromised individuals. Two cases of a VZV-related retinitis are described with the characteristic features of the recently described progressive outer retinal necrosis (PORN) syndrome. Both patients suffered from the acquired immunodeficiency syndrome (AIDS) with greatly reduced peripheral blood CD4+ T lymphocyte counts, and presented with macular retinitis without vitritis. The disease was bilateral in one case and unilateral in the other. The clinical course was rapidly progressive with widespread retinal involvement and the development of rhegmatogenous retinal detachment with complete loss of vision in the affected eyes despite intensive intravenous antiviral therapy. VZV DNA was identified in vitreous biopsies, by molecular techniques based on the polymerase chain reaction (PCR), in both patients. At present, the use of very high-dose intravenous acyclovir may be the best therapeutic option in these patients for whom the visual prognosis is poor. Intravitreal antiviral drugs could also contribute to the management of these cases.

  18. ASSESSMENT OF THE SKIN AND RETINAL MICROVASCULATURE WITH THE OPTICAL METHODS OF DIAGNOSTICS IN PATIENTS WITH DIABETES MELLITUS

    Directory of Open Access Journals (Sweden)

    K. E. Kotliar

    2016-01-01

    Full Text Available Background: Abnormalities of microvasculature could be an early marker of diabetic complications. Therefore, its non-invasive assessment in diabetic patient seems highly relevant. Aim: To assess microcirculation in the skin and retina of patients with diabetes mellitus using optical diagnostic techniques: laser Doppler flowmetry (LDF and Retinal Vessel Analyser (RVA. Materials and methods: Cutaneous microcirculation rhythms were analyzed in 18 patients with type 2 diabetes mellitus and 16 healthy volunteers in the MONIKI (Moscow, Russia. Microcirculation in the dorsal hand and foot skin was assessed by LDF for 2 minutes. The amplitude and frequencies of perfusion oscillations corresponding to the rhythms of various etiologies were computed by Waveletanalysis. Retinal vasomotions and their changes were studied in 33 type 1 diabetic patients compared to 33 healthy volunteers in the Aachen University of Applied Sciences (Germany. Original recordings made by the RVA were used for the analysis with a  Fourier transformation, cross-correlation and autocorrelation. Results: There was no significant difference in the hand skin microcirculation rhythms assessed by LDF between patients with diabetes mellitus and healthy volunteers, whereas in the lower extremities, statistically significant differences were found in the amplitude of high-frequency oscillations corresponding to the range of the heart rhythm. These results correlate well with the results of the optical assessment of retinal vasculature, where statistically significant differences in the amplitude of high frequency oscillations corresponding to the heart rate were found. In type 1 diabetic patients the periodicity of venous pulsation was higher than in the control healthy group. Conclusion: Both dynamic analysis of the pulsations and vasomotions of retinal vessels assessed by RVA and analysis of the rhythms of blood circulation in the skin of the lower extremities measured by LDF revealed

  19. RETINAL VASCULAR PATHOLOGY RISK DEVELOPMENT IN THE IRRADIATED AT DIFFERENT AGES AS A RESULT OF CHERNOBYL NPP ACCIDENT.

    Science.gov (United States)

    Fedirko, P A; Babenko, T F; Dorichevska, R Yu; Garkava, N A

    2015-12-01

    To assess the relationship between the age at which a person undergoes radiation exposure and risk of developing eye lesions (case study of the retinal angiopathy prevalence). The object of the study was the state of the retinal vessels in 2,531 persons (1,948 evacuated from the city of Pripyat under the age of 20 and 583 exposed to radiation in utero as a result of the Chernobyl NPP disaster. The results of standardized ophthalmic examination conducted from 1993 to 2000 within the framework of Clinical and epidemiological registry are used for the analysis. The evacuees were subdivided into different age groups of the exposed to radiation. The cohort of control group formed corresponding age groups of the unirradiated control. Statistical analysis of the survey results was carried out using the free trial version of «Open Epi 2.2.1» software package. The results obtained revealed a significant prevalence of retinal vessels pathology in all groups. The difference in angiopathy prevalence in exposed in utero persons was significant compared to age-control. The prevalence of retinal vascular pathology was also significantly higher in all groups of evacuees. Angiopathy prevalence was higher in the group exposed in utero and at the age of 8-12 years, and in the group of people who were exposed at the age of 4-7 years, the risk of angiopathy was lower. It is proved that the occurrence of distant radiation effects mainly depends on the age at which a person has undergone irradiation. It should be noted that all the other conditions were approximately the same. If working conditions of the persons who were exposed in utero or were aged 8 to 20 years when the Chernobyl disaster happened are connected with occupational radiation exposure it is necessary to take additional preventive measures. P. А. Fedirko, T. F. Babenko, R. Yu. Dorichevska, N. А. Garkava.

  20. Investigation of vessel visibility of iterative reconstruction method in coronary computed tomography angiography using simulated vessel phantom

    International Nuclear Information System (INIS)

    Inoue, Takeshi; Uto, Fumiaki; Ichikawa, Katsuhiro; Hara, Takanori; Urikura, Atsushi; Hoshino, Takashi; Miura, Youhei; Terakawa, Syouichi

    2012-01-01

    Iterative reconstruction methods can reduce the noise of computed tomography (CT) images, which are expected to contribute to the reduction of patient dose CT examinations. The purpose of this study was to investigate impact of an iterative reconstruction method (iDose 4 , Philips Healthcare) on vessel visibility in coronary CT angiography (CTA) by using phantom studies. A simulated phantom was scanned by a CT system (iCT, Philips Healthcare), and the axial images were reconstructed by filtered back projection (FBP) and given a level of 1 to 7 (L1-L7) of the iterative reconstruction (IR). The vessel visibility was evaluated by a quantitative analysis using profiles across a 1.5-mm diameter simulated vessel as well as visual evaluation for multi planar reformation (MPR) images and volume rendering (VR) images in terms of the normalized-rank method with analysis of variance. The peak CT value of the profiles decreased with IR level and full width at half maximum of the profile also decreased with the IR level. For normalized-rank method, there was no statistical difference between FBP and L1 (20% dose reduction) for both MPR and VR images. The IR levels higher than L1 sacrificed the spatial resolution for the 1.5-mm simulated vessel, and their visual vessel visibilities were significantly inferior to that of the FBP. (author)

  1. Confinement Vessel Assay System: Design and Implementation Report

    International Nuclear Information System (INIS)

    Frame, Katherine C.; Bourne, Mark M.; Crooks, William J.; Evans, Louise; Mayo, Douglas R.; Gomez, Cipriano D.; Miko, David K.; Salazar, William R.; Stange, Sy; Vigil, Georgiana M.

    2012-01-01

    Los Alamos National Laboratory has a number of spherical confinement vessels remaining from tests involving nuclear materials. These vessels have an inner diameter of 6 feet with 1- to 2-inch thick steel walls. The goal of the Confinement Vessel Disposition (CVD) project is to remove debris and reduce contamination inside the vessels. We have developed a neutron assay system for the purposes of Materials Control and Accountability (MC and A) measurements of the vessel prior to and after cleanout. We present our approach to confronting the challenges in designing, building, and testing such a system. The system was designed to meet a set of functional and operational requirements. A Monte Carlo model was developed to aid in optimizing the detector design as well as to predict the systematic uncertainty associated with confinement vessel measurements. Initial testing was performed to optimize and determine various measurement parameters, and then the system was characterized using 252 Cf placed a various locations throughout the measurement system. Measurements were also performed with a 252 Cf source placed inside of small steel and HDPE shells to study the effect of moderation. These measurements compare favorably with their MCNPX model equivalent, making us confident that we can rely on the Monte Carlo simulation to predict the systematic uncertainty due to variations in response to material that may be localized at different points within a vessel.

  2. The relationship between retinal damage and current intensity in a pre-clinical suprachoroidal-transretinal stimulation model using a laser-formed microporous electrode

    Science.gov (United States)

    Kanda, Hiroyuki; Nakano, Yukari; Terasawa, Yasuo; Morimoto, Takeshi; Fujikado, Takashi

    2017-10-01

    Objective. Suprachoroidal-transretinal stimulation (STS) is a stimulation method for retinal prostheses. For STS-type retinal prostheses, we developed a new type of stimulating electrode called a femtosecond laser-induced porous electrode (FLiP electrode). To verify the safety of the FLiP electrode for STS, we investigated the characteristics of STS-induced retinal injury. Approach. Sixteen eyes of pigmented rabbits were studied in this in vivo study. For each examined eye, we implanted a single-channel FLiP electrode (diameter, 0.5 mm height, 0.3 mm geometric surface area, 0.43 mm2) in a scleral pocket created at the posterior pole of the eye. A return electrode (diameter, 0.5 mm length, 3 mm) was inserted into the vitreous cavity. The eyes were divided into five groups, and each group was stimulated with a different current intensity. The stimulus intensities and the number of eyes in each group were as follows: 1.0 mA (n  =  2), 1.5 mA (n  =  3), 2.0 mA (n  =  3), 2.5 mA (n  =  4), and 3.0 mA (n  =  2). Continuous biphasic pulses (0.5 ms/phase) were applied under general anesthesia at a frequency of 20 Hz for 48 h. Fundus photography, fluorescein angiography (FA), and optical coherence tomography were performed before and after applying the electrical stimulation to evaluate the retinal injury. Main results. The 1.0 mA and 1.5 mA groups showed little or no retinal damage. Fluorescent dye leakage in FA and punctate pigmentation in the fundus were observed around the stimulation site with stimulation of 2.0 mA (1/3), 2.5 mA (1/4), and 3.0 mA (2/2). Significance. Our findings indicate that the threshold current for inducing retinal damage is greater than that for eliciting electrical phosphenes (<1 mA) with STS observed in human trials. Therefore, STS by the FLiP electrode is a safe and feasible stimulation method for retinal prostheses as long as it is used with these pulse parameters.

  3. A 2D driven 3D vessel segmentation algorithm for 3D digital subtraction angiography data

    International Nuclear Information System (INIS)

    Spiegel, M; Hornegger, J; Redel, T; Struffert, T; Doerfler, A

    2011-01-01

    Cerebrovascular disease is among the leading causes of death in western industrial nations. 3D rotational angiography delivers indispensable information on vessel morphology and pathology. Physicians make use of this to analyze vessel geometry in detail, i.e. vessel diameters, location and size of aneurysms, to come up with a clinical decision. 3D segmentation is a crucial step in this pipeline. Although a lot of different methods are available nowadays, all of them lack a method to validate the results for the individual patient. Therefore, we propose a novel 2D digital subtraction angiography (DSA)-driven 3D vessel segmentation and validation framework. 2D DSA projections are clinically considered as gold standard when it comes to measurements of vessel diameter or the neck size of aneurysms. An ellipsoid vessel model is applied to deliver the initial 3D segmentation. To assess the accuracy of the 3D vessel segmentation, its forward projections are iteratively overlaid with the corresponding 2D DSA projections. Local vessel discrepancies are modeled by a global 2D/3D optimization function to adjust the 3D vessel segmentation toward the 2D vessel contours. Our framework has been evaluated on phantom data as well as on ten patient datasets. Three 2D DSA projections from varying viewing angles have been used for each dataset. The novel 2D driven 3D vessel segmentation approach shows superior results against state-of-the-art segmentations like region growing, i.e. an improvement of 7.2% points in precision and 5.8% points for the Dice coefficient. This method opens up future clinical applications requiring the greatest vessel accuracy, e.g. computational fluid dynamic modeling.

  4. Retinal Detachment

    Directory of Open Access Journals (Sweden)

    Adnan Riaz, MD

    2018-04-01

    Full Text Available History of present illness: A 58-year-old female presented to the emergency department reporting six days of progressive, atraumatic left eye vision loss. Her symptoms started with the appearance of dark spots and “spider webs,” and then progressed to darkening of vision in her left eye. She reports mild pain since yesterday. Her review of symptoms was otherwise negative. Ocular physical examination revealed normal external appearance, intact extraocular movements, and visual acuities of 20/25 OD and light/dark sensitivity OS. Fluorescein uptake was negative and slit lamp exam was unremarkable. Significant findings: Bedside ocular ultrasound revealed a serpentine, hyperechoic membrane that appeared tethered to the optic disc posteriorly with hyperechoic material underneath. These findings are consistent with retinal detachment (RD and associated retinal hemorrhage. Discussion: The retina is a layer of organized neurons that line the posterior portion of the posterior chamber of the eye. RD occurs when this layer separates from the underlying epithelium, resulting in ischemia and progressive photoreceptor degeneration, with potentially rapid and permanent vision loss if left untreated.1 Risk factors include advanced age, male sex (60%, race (Asians and Jews, and myopia and lattice degeneration.2 Bedside ultrasound (US performed by emergency physicians provides a valuable tool that has been used by ophthalmologists for decades to evaluate intraocular disease.1,3 Findings on bedside ultrasound consistent with RD include a hyperechoic membrane floating in the posterior chamber. RD usuallyremain tethered to the optic disc posteriorly and do not cross midline, a feature distinguishing them from posterior vitreous detachments. Associated retinal hemorrhage, seen as hyperechoic material under the retinal flap, can often be seen.1,2 US can also distinguish between “mac-on” and “mac-off” detachments. If the retina is still attached to the

  5. Decellularized ovine arteries as small-diameter vascular grafts

    International Nuclear Information System (INIS)

    Mancuso, L; Cao, G; Gualerzi, A; Boschetti, F; Loy, F

    2014-01-01

    Atherosclerosis and its complications still represent the leading cause of death in the developed countries. While autologous blood vessels may be regarded as the best solution for peripheral and coronary bypass, they are unavailable in most patients. Even though tissue engineering techniques are often applied to the development of small-diameter vascular grafts, limiting factors of this approach are represented by the lack of essential extracellular matrix proteins and/or poor biomechanical properties of the scaffolds used. Along these lines, the aim of this study was to develop a decellularization protocol for ovine carotids to be used as suitable small-diameter vascular grafts. Samples were treated either with sodium dodecyl sulphate (SDS) or with Trypsin and Triton X-100; a final nuclease digestion was performed for both protocols. Morphological analyses demonstrate complete removal of nuclei and cellular components in treated vessels, also confirmed by significant reduction in wall thickness and DNA content. Essential extracellular matrix proteins such as collagen, elastin, and fibronectin are well preserved after decellularization. From a mechanical point of view, Trypsin and Triton X-100 treated arteries show elastic modules and compliance comparable to native carotids, whereas the use of SDS makes samples stiffer, with a significant decrease in the compliance mean value and an increase in longitudinal and circumferential Young’s modules. It is demonstrated that the treatment where Trypsin and Triton X-100 are combined guarantees complete decellularization of carotids, with no significant alteration of biomechanical and structural properties, thus preserving a suitable environment for adhesion, proliferation, and migration of cells. (paper)

  6. Peripapillary retinal thermal coagulation following electrical injury

    Directory of Open Access Journals (Sweden)

    Manjari Tandon

    2013-01-01

    Full Text Available In this study, we have presented the case report of a 20 year old boy who suffered an electric injury shock, following which he showed peripapillary retinal opacification and increased retinal thickening that subsequently progressed to retinal atrophy. The fluorescein angiogram revealed normal retinal circulation, thus indicating thermal damage to retina without any compromise to retinal circulation.

  7. Automatic detection and classification of malarial retinopathy- associated retinal whitening in digital retinal images

    International Nuclear Information System (INIS)

    Akram, M.U.; Alvi, A.B.N.; Khan, S.A.

    2017-01-01

    Malarial retinopathy addresses diseases that are characterized by abnormalities in retinal fundus imaging. Macular whitening is one of the distinct signs of cerebral malaria but has hardly been explored as a critical bio-marker. The paper proposes a computerized detection and classification method for malarial retinopathy using retinal whitening as a bio-marker. The paper combines various statistical and color based features to form a sound feature set for accurate detection of retinal whitening. All features are extracted at image level and feature selection is performed to detect most discriminate features. A new method for macula location is also presented. The detected macula location is further used for grading of whitening as macular or peripheral whitening. Support vector machine along with radial basis function is used for classification of normal and malarial retinopathy patients. The evaluation is performed using a locally gathered dataset from malarial patients and it achieves an accuracy of 95% for detection of retinal whitening and 100% accuracy for grading of retinal whitening as macular or non-macular. One of the major contributions of proposed method is grading of retinal whitening into macular or peripheral whitening. (author)

  8. Evolution of Outer Retinal Folds Occurring after Vitrectomy for Retinal Detachment Repair

    NARCIS (Netherlands)

    Dell'Omo, Roberto; Tan, H. Stevie; Schlingemann, Reinier O.; Bijl, Heico M.; Lesnik Oberstein, Sarit Y.; Barca, Francesco; Mura, Marco

    2012-01-01

    PURPOSE. To assess the evolution of outer retinal folds (ORFs) occurring after repair of rhegmatogenous retinal detachment (RRD) using spectral domain-optical coherence tomography (sd-OCT) and fundus autofluorescence (FAF), and to discuss their pathogenesis. METHODS. Twenty patients were operated on

  9. Retinitis pigmentosa, Coats disease and uveitis.

    Science.gov (United States)

    Solomon, A; Banin, E; Anteby, I; Benezra, D

    1999-01-01

    To study the anamnestic immune response to retinal specific antigens of two patients suffering from a rare triad of retinitis pigmentosa, Coats disease and uveitis. 17-year-old girl presented with an acute episode of panuveitis, and her 19-year-old brother suffered from chronic uveitis. On examination, both patients showed retinal vascular changes and subretinal exudations typical of Coats disease, with bone-spicule pigmentary changes as observed in retinitis pigmentosa. All routine examinations were unrevealing. However, the peripheral lymphocytes from these two siblings gave a specific anamnestic response to retinal antigens in vitro. A stimulation index of 4.6 was obtained when the sister's lymphocytes were stimulated with interphotoreceptor binding protein, IRBP--during the acute stage of the uveitis. The brother's lymphocytes showed a stimulation index of 2.7 towards S-Ag during the chronic phase of his uveitic condition. These results indicate that autoimmunity towards retinal antigens may play some role in specific types of retinitis pigmentosa. Whether these autoimmune reactions are a primary pathological mechanism or are secondary to the extensive destruction of the photoreceptor layer resulting from the retinitis pigmentosa remains debatable.

  10. Serum Phosphate and Retinal Microvascular Changes: The Multi-Ethnic Study of Atherosclerosis and the Beaver Dam Eye Study.

    Science.gov (United States)

    Mehta, Rupal; Hodakowski, Alexander; Cai, Xuan; Lee, Kris E; Kestenbaum, Bryan R; de Boer, Ian H; Fawzi, Amani; Wong, Tien Yin; Ix, Joachim; Klein, Barbara; Klein, Ronald; Isakova, Tamara

    2017-12-01

    Higher levels of serum phosphate are strongly linked to increased risk of cardiovascular disease and therapies aimed to lower serum phosphate are employed in the management of patients with chronic kidney disease (CKD). Data are limited, however, on serum phosphate as a risk factor for microvascular disease in community-based populations. It is important to determine the impact of novel risk factors, such as phosphate, on the microvasculature. We conducted a prospective study of 3919 individuals in the Multi-Ethnic Study of Atherosclerosis (MESA) and 3544 individuals in the Beaver Dam Eye Study (BDES) to test the associations of serum phosphate with retinopathy and retinal vessel caliber, and change in retinopathy severity and change in retinal vessel caliber. Mean (standard deviation) serum phosphate was 3.66 (0.52) mg/dl in the MESA and 3.77 (0.55) mg/dl in the BDES. In multivariable adjusted models, phosphate was significantly associated with prevalent retinopathy in the MESA (Odds Ratio [OR] per 1 mg/dl increase in phosphate, 1.22; Confidence Interval [CI] 1.02-1.47) and the BDES (OR 1.06; CI 1.01-1.11). In stratified analyses, these relationships were even stronger and only seen in individuals with diabetes in both the MESA (OR 1.81; CI 1.30-2.53) and the BDES (OR 1.16; CI 1.05-1.29). Phosphate was not associated with incident or change in retinopathy severity, nor any retinal caliber outcome. Among community-living individuals with low prevalence of CKD, higher serum phosphate was associated with prevalent retinopathy in individuals with diabetes. Further longitudinal assessments in patients with diabetes necessitate further investigation.

  11. Retinal vascular pathology risk development in the irradiated at different ages as a result if Chornobyl NPP accident

    International Nuclear Information System (INIS)

    Fedyirko, P.A.; Babenko, T.F.; Doryichevs'ka, R.Yu.; Gar'kava, N.A.

    2015-01-01

    The object of the study was the state of the retinal vessels in 2,531 persons (1,948 evacuated from the city of Pripyat under the age of 20 and 583 exposed to radiation in utero as a result of the Chornobyl NPP disaster. The results of standardized ophthalmic examination conducted from 1993 to 2000 within the framework of Clinical and epidemiological registry are used for the analysis. The evacuees were subdivided into different age groups of the exposed to radiation. The cohort of control group formed corresponding age groups of the unirradiated control. Statistical analysis of the survey results was carried out using the free trial version of ''Open Epi 2.2.1'' software package. The results obtained revealed a significant prevalence of retinal vessels pathology in all groups. The difference in angiopathy prevalence in exposed in utero persons was significant compared to age control. The prevalence of retinal vascular pathology was also significantly higher in all groups of evacuees. Angiopathy prevalence was higher in the group exposed in utero and at the age of 8-12 years, and in the group of people who were exposed at the age of 4-7 years, the risk of angiopathy was lower. It is proved that the occurrence of distant radiation effects mainly depends on the age at which a person has undergone irradiation. It should be noted that all the other conditions were approximately the same. If working conditions of the persons who were exposed in utero or were aged 8 to 20 years when the Chornobyl disaster happened are connected with occupational radiation exposure it is necessary to take additional preventive measures

  12. Pressure vessels for reactors made from structural steel with limited tensile strength

    International Nuclear Information System (INIS)

    Machatti, H.

    1973-01-01

    The reactor pressure vessel is prestressed in several directions with prestressing elements fabricated of steel with a high yielding point. This design allows a substantial reduction of wall thickness or an increase of the inner diameter at equal wall thickness. The prestress of the prestressing elements is designed to achieve a maximum stress release of the vessel walls at normal operating conditions and to fully utilize the maximum load of the vessel walls. For safety reasons the cross section of the prestressing elements is constructed in a way that strain is always 20 % lower the yield point. (P.K.)

  13. Regulation of Taurine transporter activity in cultured rat retinal ganglion cells and rat retinal Muller Cells

    International Nuclear Information System (INIS)

    Eissa, Laila A.; Smith, Sylvia B.; El-sherbeny, Amira A.

    2006-01-01

    Diabetic retinopathy is one of the most common complications of diabetes. The amino acid taurine is believed to play an antioxidant protective role in diabetic retinopathy through the scavenging of the reactive species. It is not well established whether taurine uptake is altered in retina cells during diabetic conditions. Thus, the present study was designed to investigate the changes in taurine transport in cultures of rat retinal Muller cells and rat retinal ganglion cells under conditions associated with diabetes. Taurine was abundantly taken up by retinal Muller cells and rat retinal ganglion cells under normal glycemic condition. Taurine was actively transported to rat Muller cells and rat retinal ganglion cells in a Na and Cl dependant manner. Taurine uptake further significantly elevated in both type of cells after the incubation with high glucose concentration. This effect could be attributed to the increase in osmolarity. Because Nitric Oxide (NO) is a molecule implicated in the pathogenesis of diabetes, we also determined the activity of taurine transporter in cultured rat retinal Muller cells and rat retinal ganglion cells in the presence of the NO donors, SIN-1 and SNAP. Taurine uptake was elevated above control value after 24-h incubation with low concentration of NO donors. We finally investigated the ability of neurotoxic glutamate to change taurine transporter activity in both types of cells. Uptake of taurine was significantly increased in rat retinal ganglion cells when only incubated with high concentration of glutamate. Our data provide evidence that taurine transporter is present in cultured rat retinal ganglion and Muller cells and is regulated by hyperosmolarity. The data are relevant to disease such as diabetes and neuronal degeneration where retinal cell volume may dramatically change. (author)

  14. Outcomes in bullous retinal detachment

    Directory of Open Access Journals (Sweden)

    Sarah P. Read

    2017-06-01

    Conclusions and importance: GRTs are an uncommon cause of retinal detachment. While pars plana vitrectomy with tamponade is standard in GRT management, there is variability in the use of scleral buckling and PFO in these cases. This is in contrast to retinal dialysis where scleral buckle alone can yield favorable results. Though a baseball ocular trauma is common, retinal involvement is rare compared to other sports injuries such as those occurring with tennis, soccer and golf. Sports trauma remains an important cause of retinal injury and patients should be counseled on the need for eye protection.

  15. Apelin Protects Primary Rat Retinal Pericytes from Chemical Hypoxia-Induced Apoptosis

    Directory of Open Access Journals (Sweden)

    Li Chen

    2015-01-01

    Full Text Available Pericytes are a population of cells that participate in normal vessel architecture and regulate permeability. Apelin, as the endogenous ligand of G protein-coupled receptor APJ, participates in a number of physiological and pathological processes. To date, the effect of apelin on pericyte is not clear. Our study aimed to investigate the potential protection mechanisms of apelin, with regard to primary rat retinal pericytes under hypoxia. Immunofluorescence staining revealed that pericytes colocalized with APJ in the fibrovascular membranes dissected from proliferative diabetic retinopathy patients. In the in vitro studies, we first demonstrated that the expression of apelin/APJ was upregulated in pericytes under hypoxia, and apelin increased pericytes proliferation and migration. Moreover, knockdown of apelin in pericyte was achieved via lentivirus-mediated RNA interference. After the inhibition of apelin, pericytes proliferation was inhibited significantly in hypoxia culture condition. Furthermore, exogenous recombinant apelin effectively prevented hypoxia-induced apoptosis through downregulating active-caspase 3 expression and increasing the ratio of B cell lymphoma-2 (Bcl-2/Bcl-2 associated X protein (Bax in pericytes. These results suggest that apelin suppressed hypoxia-induced pericytes injury, which indicated that apelin could be a potential therapeutic target for retinal angiogenic diseases.

  16. Enhanced generation of retinal progenitor cells from human retinal pigment epithelial cells induced by amniotic fluid.

    Science.gov (United States)

    Sanie-Jahromi, Fatemeh; Ahmadieh, Hamid; Soheili, Zahra-Soheila; Davari, Maliheh; Ghaderi, Shima; Kanavi, Mozhgan Rezaei; Samiei, Shahram; Deezagi, Abdolkhalegh; Pakravesh, Jalil; Bagheri, Abouzar

    2012-04-10

    Retinal progenitor cells are a convenient source of cell replacement therapy in retinal degenerative disorders. The purpose of this study was to evaluate the expression patterns of the homeobox genes PAX6 and CHX10 (retinal progenitor markers) during treatment of human retinal pigment epithelium (RPE) cells with amniotic fluid (AF), RPE cells harvested from neonatal cadaver globes were cultured in a mixture of DMEM and Ham's F12 supplemented with 10% FBS. At different passages, cells were trypsinized and co-cultured with 30% AF obtained from normal fetuses of 1416 weeks gestational age. Compared to FBS-treated controls, AF-treated cultures exhibited special morphological changes in culture, including appearance of spheroid colonies, improved initial cell adhesion and ordered cell alignment. Cell proliferation assays indicated a remarkable increase in the proliferation rate of RPE cells cultivated in 30% AF-supplemented medium, compared with those grown in the absence of AF. Immunocytochemical analyses exhibited nuclear localization of retinal progenitor markers at a ratio of 33% and 27% for CHX10 and PAX6, respectively. This indicated a 3-fold increase in retinal progenitor markers in AF-treated cultures compared to FBS-treated controls. Real-time PCR data of retinal progenitor genes (PAX6, CHX10 and VSX-1) confirmed these results and demonstrated AF's capacity for promoting retinal progenitor cell generation. Taken together, the results suggest that AF significantly promotes the rate of retinal progenitor cell generation, indicating that AF can be used as an enriched supplement for serum-free media used for the in vitro propagation of human progenitor cells.

  17. Induced Retro-Differentiation of Human Retinal Pigment Epithelial Cells on PolyHEMA.

    Science.gov (United States)

    Nazemroaya, Fatemeh; Soheili, Zahra-Soheila; Samiei, Shahram; Deezagi, Abdolkhalegh; Ahmadieh, Hamid; Davari, Malihe; Heidari, Razeih; Bagheri, Abouzar; Darvishalipour-Astaneh, Shamila

    2017-10-01

    Retinal pigment epithelium (RPE) cells represent a great potential to rescue degenerated cells of the damaged retina. Activation of the virtually plastic properties of RPE cells may aid in recovery of retinal degenerative disorders without the need for entire RPE sheet transplantation. Poly (2-hydroxyethyl methacrylate)(PolyHEMA) is one of the most important hydrogels in the biomaterials world. This hydrophobic polymer does not normally support attachment of mammalian cells. In the current study we investigated the effect of PolyHEMA as a cell culture substrate on the growth, differentiation, and plasticity of hRPE cells. hRPE cells were isolated from neonatal human globes and cultured on PolyHEMA and polystyrene substrates (as controls) in 24-well culture plates. DMEM/F12 was supplemented with 10% fetal bovine serum (FBS) and/or 30% human amniotic fluid (HAF) for cultured cells on polystyrene and PolyHEMA coated vessels. Morphology, rate of cell proliferation and cell death, MTT assay, immunocytochemistry and Real-Time RT-PCR were performed to investigate the effects of PolyHEMA on the growth and differentiation of cultured hRPE cells. Proliferation rate of the cells that had been cultured on PolyHEMA was reduced; PolyHEMA did not induce cell death in the hRPE cultures. hRPE cells cultured on PolyHEMA formed many giant spheroid colonies. The giant colonies were re-cultured and the presence of retinal progenitor markers and markers of hRPE cells were detected in cell cultures on PolyHEMA. PolyHEMA seems to be promising for both maintenance and de-differentiation of hRPE cells and expansion of the retinal progenitor cells from the cultures that are originated from hRPE cells. J. Cell. Biochem. 118: 3080-3089, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  18. Vertebral Artery Diameter and Flow: Nature or Nurture.

    Science.gov (United States)

    Tarnoki, Adam Domonkos; Fejer, Bence; Tarnoki, David Laszlo; Littvay, Levente; Lucatelli, Pierleone; Cirelli, Carlo; Fanelli, Fabrizio; Sacconi, Beatrice; Fagnani, Corrado; Medda, Emanuela; Farina, Filippo; Meneghetti, Giorgio; Horvath, Tamas; Pucci, Giacomo; Schillaci, Giuseppe; Stazi, Maria Antonietta; Baracchini, Claudio

    2017-09-01

    In contrast with the carotid arteries, the vertebral arteries (VAs) show considerable variation in length, caliber, and vessel course. This study investigated whether the variation in diameter and flow characteristics of the VAs might be inherited. A total of 172 Italian twins from Padua, Perugia, and Terni (54 monozygotic, 32 dizygotic) recruited from the Italian Twin Registry underwent B-mode and pulsed-wave Doppler ultrasound assessment of their VAs. VA diameters, peak systolic velocity (PSV) and end diastolic velocity (EDV) were assessed at the level of a horizontal V2 segment. Univariate quantitative genetic modeling was performed. Fourteen percent of the sample had VA hypoplasia. Within pair correlation in monozygotic twins was higher than in dizygotics (.552 vs. .229) for VA diameter. Age- and sex-adjusted genetic effect, under the most parsimonious model, accounted for 54.7% (95% CI: 42.2-69.1%) of the variance of VA diameter, and unshared environmental effect for 45.3% (95% CI: 30.9-57.8%). No heritability was found for the PSV of VA, but shared (34.1%; 95% CI: 16.7-53.7%) and unshared (65.9%; 95% CI: 45.9-83.1%) environmental factors determined the variance. EDV of VA is moderately genetically influenced (42.4%; 95% CI: 16.1-64.9%) and also determined by the unshared environment (57.6%; 95% CI: 34.7-83.7%). The diameter of the VAs is moderately genetically determined. Different factors influence the PSV and EDV of VAs, which may highlight the complex hemodynamic background of VA flow and help to understand the vertebral flow anomalies found by ultrasound. Copyright © 2017 by the American Society of Neuroimaging.

  19. A system for the thermal insulation of a pre-stressed concrete vessel

    International Nuclear Information System (INIS)

    Aubert, Gilles; Petit, Guy.

    1975-01-01

    This invention concerns the thermal insulation of a pre-stressed concrete vessel for a pressurised water nuclear reactor, this vessel being fitted internally with a leak-proof metal lining. Two rings are placed at the lower and upper parts of the vessel respectively. The upper ring is closed with a cover. These rings differ in diameter, are fitted with a metal insulating and mark the limits of a chamber between the vaporisable fluid and the internal wall of the vessel. This chamber is filled with a fluid in the liquid phase up to the liquid/vapor interface level of the fluid and with a gas above that level, the covering of the rings forming a cold fluid liquid seal. Each ring is supported by the vessel. Leak-proof components take up the radial expansion of the rings [fr

  20. Design of vacuum vessel for Indian Test Facility (INTF) for 100 keV neutral beams

    International Nuclear Information System (INIS)

    Joshi, Jaydeep; Yadav, Ashish; Gangadharan, Roopesh; Prasad, Rambilas; Ulahannan, Shino; Rotti, Chandramouli; Bandyopadhyay, Mainak; Chakraborty, Arun

    2015-01-01

    Highlights: • Thickness calculation and optimization for the main shell, ducts, Dishends and top lid on the main shell. • Nozzle and flange design for the port openings. • Support structure design for the main shell and ducts. • FEA validation of the INTF vessel for operational, seismic and lifting condition. - Abstract: The Indian Test Facility (INTF) vacuum vessel is designed to install a full-scale test set-up of Diagnostic Neutral Beam (DNB) [1] for the qualification of beam parameters and the behavior of beam-line components prior to installation and operation in ITER. Vacuum vessel is designed in cylindrical shape having length of ∼9 m with diameter of ∼4.5 m and has a detachable top-lid for mounting as well as removal of internal components during installation and maintenance phases. The Vessel has hemispherical dish-ends with large openings for high-voltage bushing on one side and duct on another side. Vessel is provided with openings for hydraulic, cryo, gas-feed and diagnostics. Vessel duct is composed of three segments with length ranges from 3 m to 5 m with diameter of ∼1.5 m and one vessel at the end to house the second calorimeter. The objective of this paper is to present the design and analysis of vacuum vessel, with respect to its functional and operational requirements. The design calculations are done as per ASME-BPVC SectionVIII-Div.1 and subsequently Finite Element Analysis (FEM) method has been adopted to verify the design.

  1. Design of vacuum vessel for Indian Test Facility (INTF) for 100 keV neutral beams

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Jaydeep, E-mail: Jaydeep.joshi@iter-india.org [ITER-India, Institute for Plasma Research, A29, GIDC Electronics Estate, Gandhinagar 382016, Gujarat (India); Yadav, Ashish; Gangadharan, Roopesh [ITER-India, Institute for Plasma Research, A29, GIDC Electronics Estate, Gandhinagar 382016, Gujarat (India); Prasad, Rambilas [Madan Mohan Malaviya University of Technology, Gorakhpur, Uttar Pradesh 273001 (India); Ulahannan, Shino [Airframe Aerodesigns Pvt. Ltd., HAL Airport Exit Road, Old Airport Road, Bengaluru 17 (India); Rotti, Chandramouli; Bandyopadhyay, Mainak; Chakraborty, Arun [ITER-India, Institute for Plasma Research, A29, GIDC Electronics Estate, Gandhinagar 382016, Gujarat (India)

    2015-10-15

    Highlights: • Thickness calculation and optimization for the main shell, ducts, Dishends and top lid on the main shell. • Nozzle and flange design for the port openings. • Support structure design for the main shell and ducts. • FEA validation of the INTF vessel for operational, seismic and lifting condition. - Abstract: The Indian Test Facility (INTF) vacuum vessel is designed to install a full-scale test set-up of Diagnostic Neutral Beam (DNB) [1] for the qualification of beam parameters and the behavior of beam-line components prior to installation and operation in ITER. Vacuum vessel is designed in cylindrical shape having length of ∼9 m with diameter of ∼4.5 m and has a detachable top-lid for mounting as well as removal of internal components during installation and maintenance phases. The Vessel has hemispherical dish-ends with large openings for high-voltage bushing on one side and duct on another side. Vessel is provided with openings for hydraulic, cryo, gas-feed and diagnostics. Vessel duct is composed of three segments with length ranges from 3 m to 5 m with diameter of ∼1.5 m and one vessel at the end to house the second calorimeter. The objective of this paper is to present the design and analysis of vacuum vessel, with respect to its functional and operational requirements. The design calculations are done as per ASME-BPVC SectionVIII-Div.1 and subsequently Finite Element Analysis (FEM) method has been adopted to verify the design.

  2. Determination of retinal surface area.

    Science.gov (United States)

    Nagra, Manbir; Gilmartin, Bernard; Thai, Ngoc Jade; Logan, Nicola S

    2017-09-01

    Previous attempts at determining retinal surface area and surface area of the whole eye have been based upon mathematical calculations derived from retinal photographs, schematic eyes and retinal biopsies of donor eyes. 3-dimensional (3-D) ocular magnetic resonance imaging (MRI) allows a more direct measurement, it can be used to image the eye in vivo, and there is no risk of tissue shrinkage. The primary purpose of this study is to compare, using T2-weighted 3D MRI, retinal surface areas for superior-temporal (ST), inferior-temporal (IT), superior-nasal (SN) and inferior-nasal (IN) retinal quadrants. An ancillary aim is to examine whether inter-quadrant variations in area are concordant with reported inter-quadrant patterns of susceptibility to retinal breaks associated with posterior vitreous detachment (PVD). Seventy-three adult participants presenting without retinal pathology (mean age 26.25 ± 6.06 years) were scanned using a Siemens 3-Tesla MRI scanner to provide T2-weighted MR images that demarcate fluid-filled internal structures for the whole eye and provide high-contrast delineation of the vitreous-retina interface. Integrated MRI software generated total internal ocular surface area (TSA). The second nodal point was used to demarcate the origin of the peripheral retina in order to calculate total retinal surface area (RSA) and quadrant retinal surface areas (QRSA) for ST, IT, SN, and IN quadrants. Mean spherical error (MSE) was -2.50 ± 4.03D and mean axial length (AL) 24.51 ± 1.57 mm. Mean TSA and RSA for the RE were 2058 ± 189 and 1363 ± 160 mm 2 , respectively. Repeated measures anova for QRSA data indicated a significant difference within-quadrants (P area/mm increase in AL. Although the differences between QRSAs are relatively small, there was evidence of concordance with reported inter-quadrant patterns of susceptibility to retinal breaks associated with PVD. The data allow AL to be converted to QRSAs, which will assist further

  3. A theoretical model describing arterial flow in the DIEP flap related to number and size of perforator vessels.

    Science.gov (United States)

    Patel, Sameer A; Keller, Alex

    2008-11-01

    The deep inferior epigastric perforator flap is rapidly becoming a more widely employed method of autologous breast reconstruction. The technical considerations involved in the execution of the flap are many and include the selection of perforators to be incorporated in the flap. We attempt to give a mathematical explanation, based on the physics of flow through vessels and the properties of circuits with multiple resistances in parallel, for the clinical observations which have been arrived at through clinical experience. We compare the system of perforators to a circuit with multiple resistances in parallel. Each of these resistances represents a perforator vessel. In the event that there is only one perforator vessel, this simplifies to a single resistance in series with the capillary bed perfusing the flap. The flow through the flap is optimized by incorporation of the largest diameter perforator. Inclusion of other smaller perforators in addition to the largest diameter perforator will reduce the overall resistance, but this reduction in resistance is dependent on the diameter of the additional perforator and may not be worth the additional trauma of dissection and increased operative time. Incorporating several smaller perforators at the expense of excluding the largest diameter perforator appears to increase the overall resistance, unless the smaller perforators are only slightly smaller. We conclude that the best perfused flap involves use of the largest diameter vessel, that although adding additional perforators will decrease the resistance and increase flow, the magnitude of the benefit depends largely on the calibre of the additional perforator, and that this benefit needs to be weighed against the downside of increased muscle and facial trauma.

  4. Spectrophotometric retinal oximetry in pigs

    DEFF Research Database (Denmark)

    Traustason, Sindri; Kiilgaard, Jens Folke; Karlsson, Robert

    2013-01-01

    PURPOSE: To assess the validity of spectrophotometric retinal oximetry, by comparison to blood gas analysis and intra-vitreal measurements of partial pressure of oxygen (pO2). METHODS: Female domestic pigs were used for all experiments (n=8). Oxygen fraction in inspired air was changed using...... a mixture of room air, pure oxygen and pure nitrogen, ranging from 5% to 100% oxygen. Femoral arterial blood gas analysis and retinal oximetry was performed at each level of inspiratory oxygen fraction. Retinal oximetry was performed using a commercial instrument, the Oxymap Retinal Oximeter T1 (Oxymap ehf...... arterial oxygen saturation and the optical density ratio over retinal arteries revealed an approximately linear relationship (R(2) = 0.74, p = 3.4 x 10(-9)). In order to test the validity of applying the arterial calibration to veins, we compared non-invasive oximetry measurements to invasive pO2...

  5. Giant Retinal Tear With Retinal Detachment in Regressed Aggressive Posterior Retinopathy of Prematurity Treated by Laser.

    Science.gov (United States)

    Chandra, Parijat; Tewari, Ruchir; Salunkhe, Nitesh; Kumawat, Devesh; Kumar, Vinod

    2017-06-29

    Rhegmatogenous retinal detachment after successfully regressed retinopathy of prematurity is a rare occurrence. Late onset rhegmatogenous retinal detachment has been reported infrequently. The authors report a case of aggressive posterior retinopathy of prematurity that underwent uneventful regression after laser photocoagulation and later developed an inoperable closed funnel retinal detachment due to a giant retinal tear. This case represents the earliest development of such complications in regressed aggressive posterior retinopathy of prematurity treated by laser. Development of a giant retinal tear has also not been previously reported after laser treatment. This case highlights that successful regression of severe retinopathy of prematurity does not safeguard against future complications and requires frequent long-term follow-up. [J Pediatr Ophthalmol Strabismus. 2017;54:e34-e36.]. Copyright 2017, SLACK Incorporated.

  6. Therapeutic Effect of Bone Marrow Mesenchymal Stem Cells on Laser-Induced Retinal Injury in Mice

    Directory of Open Access Journals (Sweden)

    Yuanfeng Jiang

    2014-05-01

    Full Text Available Stem cell therapy has shown encouraging results for neurodegenerative diseases. The retina provides a convenient locus to investigate stem cell functions and distribution in the nervous system. In the current study, we investigated the therapeutic potential of bone marrow mesenchymal stem cells (MSCs by systemic transplantation in a laser-induced retinal injury model. MSCs from C57BL/6 mice labeled with green fluorescent protein (GFP were injected via the tail vein into mice after laser photocoagulation. We found that the average diameters of laser spots and retinal cell apoptosis were decreased in the MSC-treated group. Interestingly, GFP-MSCs did not migrate to the injured retina. Further examination revealed that the mRNA expression levels of glial fibrillary acidic protein and matrix metalloproteinase-2 were lower in the injured eyes after MSC transplantation. Our results suggest that intravenously injected MSCs have the ability to inhibit retinal cell apoptosis, reduce the inflammatory response and limit the spreading of damage in the laser-injured retina of mice. Systemic MSC therapy might play a role in neuroprotection, mainly by regulation of the intraocular microenvironment.

  7. Enhanced generation of retinal progenitor cells from human retinal pigment epithelial cells induced by amniotic fluid

    Directory of Open Access Journals (Sweden)

    Sanie-Jahromi Fatemeh

    2012-04-01

    Full Text Available Abstract Background Retinal progenitor cells are a convenient source of cell replacement therapy in retinal degenerative disorders. The purpose of this study was to evaluate the expression patterns of the homeobox genes PAX6 and CHX10 (retinal progenitor markers during treatment of human retinal pigment epithelium (RPE cells with amniotic fluid (AF, RPE cells harvested from neonatal cadaver globes were cultured in a mixture of DMEM and Ham's F12 supplemented with 10% FBS. At different passages, cells were trypsinized and co-cultured with 30% AF obtained from normal fetuses of 1416 weeks gestational age. Results Compared to FBS-treated controls, AF-treated cultures exhibited special morphological changes in culture, including appearance of spheroid colonies, improved initial cell adhesion and ordered cell alignment. Cell proliferation assays indicated a remarkable increase in the proliferation rate of RPE cells cultivated in 30% AF-supplemented medium, compared with those grown in the absence of AF. Immunocytochemical analyses exhibited nuclear localization of retinal progenitor markers at a ratio of 33% and 27% for CHX10 and PAX6, respectively. This indicated a 3-fold increase in retinal progenitor markers in AF-treated cultures compared to FBS-treated controls. Real-time PCR data of retinal progenitor genes (PAX6, CHX10 and VSX-1 confirmed these results and demonstrated AF's capacity for promoting retinal progenitor cell generation. Conclusion Taken together, the results suggest that AF significantly promotes the rate of retinal progenitor cell generation, indicating that AF can be used as an enriched supplement for serum-free media used for the in vitro propagation of human progenitor cells.

  8. Screening for retinitis in children with probable systemic ...

    African Journals Online (AJOL)

    CMV retinitis may be prevented by timely diagnosis and treatment. This study aimed to .... retinitis are: 'a fulminant picture of retinal vasculitis and vascular sheathing with areas of yellow-white, full thickness, retinal necrosis producing retinal oedema associated ... and intravenous foscarnet as alternatives.[4] Although CMV- ...

  9. Bioelectronic retinal prosthesis

    Science.gov (United States)

    Weiland, James D.

    2016-05-01

    Retinal prosthesis have been translated to clinical use over the past two decades. Currently, two devices have regulatory approval for the treatment of retinitis pigmentosa and one device is in clinical trials for treatment of age-related macular degeneration. These devices provide partial sight restoration and patients use this improved vision in their everyday lives to navigate and to detect large objects. However, significant vision restoration will require both better technology and improved understanding of the interaction between electrical stimulation and the retina. In particular, current retinal prostheses do not provide peripheral visions due to technical and surgical limitations, thus limiting the effectiveness of the treatment. This paper reviews recent results from human implant patients and presents technical approaches for peripheral vision.

  10. Tractional retinal detachment in Usher syndrome type II.

    Science.gov (United States)

    Rani, Alka; Pal, Nikhil; Azad, Raj Vardhan; Sharma, Yog Raj; Chandra, Parijat; Vikram Singh, Deependra

    2005-08-01

    Retinal detachment is a rare complication in patients with retinitis pigmentosa. A case is reported of tractional retinal detachment in a patient with retinitis pigmentosa and sensorineural hearing loss, which was diagnosed as Usher syndrome type II. Because of the poor visual prognosis, the patient refused surgery in that eye. Tractional retinal detachment should be added to the differential diagnoses of visual loss in patients with retinitis pigmentosa.

  11. Inherited Retinal Degenerative Disease Registry

    Science.gov (United States)

    2017-09-13

    Eye Diseases Hereditary; Retinal Disease; Achromatopsia; Bardet-Biedl Syndrome; Bassen-Kornzweig Syndrome; Batten Disease; Best Disease; Choroidal Dystrophy; Choroideremia; Cone Dystrophy; Cone-Rod Dystrophy; Congenital Stationary Night Blindness; Enhanced S-Cone Syndrome; Fundus Albipunctatus; Goldmann-Favre Syndrome; Gyrate Atrophy; Juvenile Macular Degeneration; Kearns-Sayre Syndrome; Leber Congenital Amaurosis; Refsum Syndrome; Retinitis Pigmentosa; Retinitis Punctata Albescens; Retinoschisis; Rod-Cone Dystrophy; Rod Dystrophy; Rod Monochromacy; Stargardt Disease; Usher Syndrome

  12. Retinal Macroglial Responses in Health and Disease

    Directory of Open Access Journals (Sweden)

    Rosa de Hoz

    2016-01-01

    Full Text Available Due to their permanent and close proximity to neurons, glial cells perform essential tasks for the normal physiology of the retina. Astrocytes and Müller cells (retinal macroglia provide physical support to neurons and supplement them with several metabolites and growth factors. Macroglia are involved in maintaining the homeostasis of extracellular ions and neurotransmitters, are essential for information processing in neural circuits, participate in retinal glucose metabolism and in removing metabolic waste products, regulate local blood flow, induce the blood-retinal barrier (BRB, play fundamental roles in local immune response, and protect neurons from oxidative damage. In response to polyetiological insults, glia cells react with a process called reactive gliosis, seeking to maintain retinal homeostasis. When malfunctioning, macroglial cells can become primary pathogenic elements. A reactive gliosis has been described in different retinal pathologies, including age-related macular degeneration (AMD, diabetes, glaucoma, retinal detachment, or retinitis pigmentosa. A better understanding of the dual, neuroprotective, or cytotoxic effect of macroglial involvement in retinal pathologies would help in treating the physiopathology of these diseases. The extensive participation of the macroglia in retinal diseases points to these cells as innovative targets for new drug therapies.

  13. Differential expression of T- and L-type voltage-dependent calcium channels in renal resistance vessels

    DEFF Research Database (Denmark)

    Hansen, Pernille B. Lærkegaard; Jensen, Boye L.; Andreasen, D

    2001-01-01

    The distribution of voltage-dependent calcium channels in kidney pre- and postglomerular resistance vessels was determined at the molecular and functional levels. Reverse transcription-polymerase chain reaction analysis of microdissected rat preglomerular vessels and cultured smooth muscle cells...... on vascular diameter in the afferent arteriole. We conclude that voltage-dependent L- and T-type calcium channels are expressed and of functional significance in renal cortical preglomerular vessels, in juxtamedullary efferent arterioles, and in outer medullary vasa recta, but not in cortical efferent...

  14. STUDY OF IMAGE SEGMENTATION TECHNIQUES ON RETINAL IMAGES FOR HEALTH CARE MANAGEMENT WITH FAST COMPUTING

    Directory of Open Access Journals (Sweden)

    Srikanth Prabhu

    2012-02-01

    Full Text Available The role of segmentation in image processing is to separate foreground from background. In this process, the features become clearly visible when appropriate filters are applied on the image. In this paper emphasis has been laid on segmentation of biometric retinal images to filter out the vessels explicitly for evaluating the bifurcation points and features for diabetic retinopathy. Segmentation on images is performed by calculating ridges or morphology. Ridges are those areas in the images where there is sharp contrast in features. Morphology targets the features using structuring elements. Structuring elements are of different shapes like disk, line which is used for extracting features of those shapes. When segmentation was performed on retinal images problems were encountered during image pre-processing stage. Also edge detection techniques have been deployed to find out the contours of the retinal images. After the segmentation has been performed, it has been seen that artifacts of the retinal images have been minimal when ridge based segmentation technique was deployed. In the field of Health Care Management, image segmentation has an important role to play as it determines whether a person is normal or having any disease specially diabetes. During the process of segmentation, diseased features are classified as diseased one’s or artifacts. The problem comes when artifacts are classified as diseased ones. This results in misclassification which has been discussed in the analysis Section. We have achieved fast computing with better performance, in terms of speed for non-repeating features, when compared to repeating features.

  15. Large vessel imaging using cosmic-ray muons

    International Nuclear Information System (INIS)

    Jenneson, P.M.

    2004-01-01

    Cosmic-ray muons are assessed for their practical use in the tomographic imaging of the internal composition of large vessels over 2 m in diameter. The technique is based on the attenuation and scattering of cosmic-ray muons passing through a vessel and has advantages over photon-based methods of tomography that it is extendable to object containing high-density materials over many tens of metres. The main disadvantage is the length of time required to produce images of sufficient resolution and hence cosmic ray muon tomography will be most suited to the imaging of large structures whose internal composition is effectively static for the duration of the imaging period. Simulation and theoretical results are presented here which demonstrate the feasibility of cosmic ray muon tomography

  16. MORPHOMETRIC STUDY OF THE AREOLAR SPACE BETWEEN THE GREAT VESSELS AND THE LUMBAR SPINE

    Directory of Open Access Journals (Sweden)

    Luis Marchi

    2015-12-01

    Full Text Available Objective : This work aims to study the areolar space anterior to the lumbar spine, and also the positioning of the large vessels focusing a lateral approach. Methods :This is a morphometric study of 108 cases based on T2 weighted-MRI images in the supine position. The following measurements were performed: lumbar and segmental lordosis; anteroposterior disc diameter; space between the disc/vertebral body and the vessels; bifurcation between the abdominal aorta and the common iliac veins confluence in relation to the lumbar level. Results :The areolar space with respect to the iliac veins, and with the vena cava increased cranially (p<0.001, starting from average 0.6mm at L4-L5 and reaching 8.4mm at L2, while the abdominal aorta showed no increase or decrease pattern across the different levels (p=0.135 ranging from 1.8 to 4.6mm. The diameter of the discs increased distally (p<0.01 as well as the lordosis (p<0.001. The disc diameter was 11% larger when compared to the adjacent vertebral bodies (p<0.001 and that resulted in a smaller distance of the vessels in the disc level than in the level of the adjacent vertebral bodies (p<0.001. The aortic bifurcation was generally ahead of L4 (52% and less frequently at L3-L4 (28% and L4-L5 (18%. The confluence of the veins was usually at the L4-L5 level (38% and at L5 (37%, and less frequently at L4 (26%. Conclusions : There is an identifiable plane between the great vessels and the lumbar spine which is particularly narrow in its distal portion. It is theoretically feasible to reach this plan, handle the anterior complex disc/ALL and protect the great vessels by lateral approach, however, it is challenging.

  17. Submillimeter Diameter Poly(Vinyl Alcohol) Vascular Graft Patency in Rabbit Model

    Science.gov (United States)

    Cutiongco, Marie F. A.; Kukumberg, Marek; Peneyra, Jonnathan L.; Yeo, Matthew S.; Yao, Jia Y.; Rufaihah, Abdul Jalil; Le Visage, Catherine; Ho, Jackie Pei; Yim, Evelyn K. F.

    2016-01-01

    Microvascular surgery is becoming a prevalent surgical practice. Replantation, hand reconstruction, orthopedic, and free tissue transfer procedures all rely on microvascular surgery for the repair of venous and arterial defects at the millimeter and submillimeter levels. Often, a vascular graft is required for the procedure as a means to bridge the gap between native arteries. While autologous vessels are desired for their bioactivity and non-thrombogenicity, the tedious harvest process, lack of availability, and caliber or mechanical mismatch contribute to graft failure. Thus, there is a need for an off-the-shelf artificial vascular graft that has low thrombogenic properties and mechanical properties matching those of submillimeter vessels. Poly(vinyl alcohol) hydrogel (PVA) has excellent prospects as a vascular graft due to its bioinertness, low thrombogenicity, high water content, and tunable mechanical properties. Here, we fabricated PVA grafts with submillimeter diameter and mechanical properties that closely approximated those of the rabbit femoral artery. In vitro platelet adhesion and microparticle release assay verified the low thrombogenicity of PVA. A stringent proof-of-concept in vivo test was performed by implanting PVA grafts in rabbit femoral artery with multilevel arterial occlusion. Laser Doppler measurements indicated the improved perfusion of the distal limb after implantation with PVA grafts. Moreover, ultrasound Doppler and angiography verified that the submillimeter diameter PVA vascular grafts remained patent for 2 weeks without the aid of anticoagulant or antithrombotics. Endothelial cells were observed in the luminal surface of one patent PVA graft. The advantageous non-thrombogenic and tunable mechanical properties of PVA that are retained even in the submillimeter diameter dimensions support the application of this biomaterial for vascular replacement in microvascular surgery. PMID:27376059

  18. Concentric retinitis pigmentosa: clinicopathologic correlations.

    Science.gov (United States)

    Milam, A H; De Castro, E B; Smith, J E; Tang, W X; John, S K; Gorin, M B; Stone, E M; Aguirre, G D; Jacobson, S G

    2001-10-01

    Progressive concentric (centripetal) loss of vision is one pattern of visual field loss in retinitis pigmentosa. This study provides the first clinicopathologic correlations for this form of retinitis pigmentosa. A family with autosomal dominant concentric retinitis pigmentosa was examined clinically and with visual function tests. A post-mortem eye of an affected 94 year old family member was processed for histopathology and immunocytochemistry with retinal cell specific antibodies. Unrelated simplex/multiplex patients with concentric retinitis pigmentosa were also examined. Affected family members of the eye donor and patients from the other families had prominent peripheral pigmentary retinopathy with more normal appearing central retina, good visual acuity, concentric field loss, normal or near normal rod and cone sensitivity within the preserved visual field, and reduced rod and cone electroretinograms. The eye donor, at age 90, had good acuity and function in a central island. Grossly, the central region of the donor retina appeared thinned but otherwise normal, while the far periphery contained heavy bone spicule pigment. Microscopically the central retina showed photoreceptor outer segment shortening and some photoreceptor cell loss. The mid periphery had a sharp line of demarcation where more central photoreceptors were near normal except for very short outer segments and peripheral photoreceptors were absent. Rods and cones showed abrupt loss of outer segments and cell death at this interface. It is concluded that concentric retinitis pigmentosa is a rare but recognizable phenotype with slowly progressive photoreceptor death from the far periphery toward the central retina. The disease is retina-wide but shows regional variation in severity of degeneration; photoreceptor death is severe in the peripheral retina with an abrupt edge between viable and degenerate photoreceptors. Peripheral to central gradients of unknown retinal molecule(s) may be defective

  19. Lattice degeneration of the retina and retinal detachment.

    Science.gov (United States)

    Semes, L P

    1992-01-01

    Lattice retinal degeneration is considered the most significant peripheral retinal disorder potentially predisposing to retinal breaks and retinal detachment. Lattice degeneration affects the vitreous and inner retinal layers with secondary changes as deep as the retinal pigment epithelium and perhaps the choriocapillaris. Variations in clinical appearance are the rule; geographically, lattice lesions favor the vertical meridians between the equator and the ora serrata. Lattice degeneration begins early in life and has been reported in sequential generations of the same family. Along with its customary bilateral occurrence, lattice shares other characteristics of a dystrophy. The association between the vitreous and retina in lattice lesions may be responsible for the majority of lattice-induced retinal detachments. The tumultuous event of posterior vitreous separation in the presence of abnormally strong vitreoretinal adherence is the trigger for a retinal tear that, in turn, may lead to retinal detachment. Although retinal holes in young patients with lattice degeneration may play a role in the evolution of retinal detachment, the clinical course of lattice degeneration seems to be one of dormancy rather than of progressive change. This discussion outlines the pathophysiology of lattice retinal degeneration and the relationship of pathophysiology to clinical presentation. The epidemiology of lattice degeneration is summarized, as are the possible precursors to retinal detachment. A clinical characterization of the natural history of lattice degeneration is offered, and interventions for complications are described. To conclude, management strategies from a primary-care standpoint are reviewed.

  20. Bilateral acute retinal necrosis-A case report

    Directory of Open Access Journals (Sweden)

    Prasad Palimar

    1992-01-01

    Full Text Available A 42 year old man presented with acute bilateral uveitis and necrotizing retinitis. Systemic investigations including test for AIDS and CMV retinitis were negative. Despite oral Acyclovir, both eyes progressed rapidly to retinal detachment with loss of vision. Early recognition is necessary to diagnose the bilateral acute retinal necrosis syndrome and initiate treatment. Bilateral acute retinal necrosis (BARN is a term first coined by Young and Bird in 1978 although the syndrome had been originally described by Urayama et al as an unilateral condition. This syndrome is characterized by the triad of acute confluent peripheral necrotizing retinitis, moderate to severe vasculitis and vitritis in an otherwise healthy individual. Rhegmatogenous retinal detachment occurs within two to three months of the onset of the disease and the second eye is involved in 36% of patients, usually within 6 weeks. We herein report a patient who presented with simultaneous BARN leading to retinal detachment in a matter of days. Also, to our knowledge this is the first report of this condition in India.

  1. INTERNAL LIMITING MEMBRANE PEELING-DEPENDENT RETINAL STRUCTURAL CHANGES AFTER VITRECTOMY IN RHEGMATOGENOUS RETINAL DETACHMENT.

    Science.gov (United States)

    Hisatomi, Toshio; Tachibana, Takashi; Notomi, Shoji; Koyanagi, Yoshito; Murakami, Yusuke; Takeda, Atsunobu; Ikeda, Yasuhiro; Yoshida, Shigeo; Enaida, Hiroshi; Murata, Toshinori; Sakamoto, Taiji; Sonoda, Koh-Hei; Ishibashi, Tatsuro

    2018-03-01

    To examine retinal changes after vitrectomy with internal limiting membrane (ILM) peeling, we used 3-dimensional optical coherence tomography (3D-OCT) in rhegmatogenous retinal detachment cases. The 68 eyes from 67 patients with rhegmatogenous retinal detachment were studied, including 35 detached macula cases (51%) and 33 attached macula cases. Internal limiting membrane peeling was performed with fine forceps after brilliant blue G staining. The 3D-OCT images were obtained with volume-rendering technologies from cross-sectional OCT images. The 3D-OCT detected 45 eyes (66%) with ILM peeling-dependent retinal changes, including dissociated optic nerve fiber layer appearance, dimple sign, temporal macular thinning, ILM peeling area thinning, or forceps-related retinal thinning. The ILM peeled area was detectable in only 9 eyes with 3D-OCT, whereas it was undetectable in other 59 eyes. The dissociated optic nerve fiber layer appearance was detected in 8 of the total cases (12%), and dimple signs were observed in 14 cases (21%). Forceps-related thinning was also noted in eight cases (24%) of attached macula cases and in four cases (11%) of detached macula cases. No postoperative macular pucker was noted in the observational period. The 3D-OCT clearly revealed spatial and time-dependent retinal changes after ILM peeling. The changes occurred in 2 months and remained thereafter.

  2. Non-syndromic retinitis pigmentosa

    NARCIS (Netherlands)

    Verbakel, S.K. (Sanne K.); R.A.C. van Huet (Ramon A. C.); C.J.F. Boon (Camiel); A.I. Hollander (Anneke); R.W.J. Collin (Rob); C.C.W. Klaver (Caroline); C. Hoyng (Carel); R. Roepman (Ronald); B.J. Klevering (Jeroen)

    2018-01-01

    textabstractRetinitis pigmentosa (RP) encompasses a group of inherited retinal dystrophies characterized by the primary degeneration of rod and cone photoreceptors. RP is a leading cause of visual disability, with a worldwide prevalence of 1:4000. Although the majority of RP cases are non-syndromic,

  3. Retinal Image Preprocessing: Background and Noise Segmentation

    Directory of Open Access Journals (Sweden)

    Usman Akram

    2012-09-01

    Full Text Available Retinal images are used for the automated screening and diagnosis of diabetic retinopathy. The retinal image quality must be improved for the detection of features and abnormalities and for this purpose preprocessing of retinal images is vital. In this paper, we present a novel automated approach for preprocessing of colored retinal images. The proposed technique improves the quality of input retinal image by separating the background and noisy area from the overall image. It contains coarse segmentation and fine segmentation. Standard retinal images databases Diaretdb0, Diaretdb1, DRIVE and STARE are used to test the validation of our preprocessing technique. The experimental results show the validity of proposed preprocessing technique.

  4. [Preventive treatment of retinal detachment in aphakic eyes].

    Science.gov (United States)

    Regnault, F; Bregeat, P

    1977-01-01

    We have examined 243 cases with retinal detachment occurring within 6 months following cataract surgery. In 92 of them retinal tear was due to lattice degeneration, in 66 to snail track degeneration and in 17 to equatorial degeneration. 290 other patients had preventive treatments. In this group, there were only 10 cases of retinal detachment. 9 out of 22 patients who had no preventive treatment suffered retinal detachments. There are two reasons for the occurrence of this retinal detachment in the 6 months following cataract surgery in eyes where retinal degenerations are found: (1) surgical trauma even with cryoextraction is responsible for traction of the vitreous base, (2) rapid disappearance of the hyaluronic acid in the aphakic vitreous is responsible for the degradation of the vitreous with formation of large zones of liquid vitreous. When adhesion between the vitreous and the retinal degeneration area remains, the traction is responsible for retinal tear or retinal detachment. The importance of the preventive treatment of retinal lesions prior to cataract surgery should be stressed.

  5. Effects of different endurance exercise modalities on migraine days and cerebrovascular health in episodic migraineurs: A randomized controlled trial.

    Science.gov (United States)

    Hanssen, H; Minghetti, A; Magon, S; Rossmeissl, A; Rasenack, M; Papadopoulou, A; Klenk, C; Faude, O; Zahner, L; Sprenger, T; Donath, L

    2018-03-01

    Aerobic exercise training is a promising complementary treatment option in migraine and can reduce migraine days and improve retinal microvascular function. Our aim was to elucidate whether different aerobic exercise programs at high vs moderate intensities distinctly affect migraine days as primary outcome and retinal vessel parameters as a secondary. In this randomized controlled trial, migraine days were recorded by a validated migraine diary in 45 migraineurs of which 36 (female: 28; age: 36 (SD:10)/BMI: 23.1 (5.3) completed the training period (dropout: 20%). Participants were assigned (Strata: age, gender, fitness and migraine symptomatology) to either high intensity interval training (HIT), moderate continuous training (MCT), or a control group (CON). Intervention groups trained twice a week over a 12-week intervention period. Static retinal vessel analysis, central retinal arteriolar (CRAE) and venular (CRVE) diameters, as well as the arteriolar-to-venular diameter ratio (AVR) were obtained for cerebrovascular health assessment. Incremental treadmill testing yielded maximal and submaximal fitness parameters. Overall, moderate migraine day reductions were observed (ηP2 = .12): HIT revealed 89% likely beneficial effects (SMD = 1.05) compared to MCT (SMD = 0.50) and CON (SMD = 0.59). Very large intervention effects on AVR improvement (ηP2 = 0.27), slightly favoring HIT (SMD=-0.43) over CON (SMD=0), were observed. HIT seems more effective for migraine day reduction and improvement of cerebrovascular health compared to MCT. Intermittent exercise programs of higher intensities may need to be considered as an additional treatment option in migraine patients. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  6. Analysis of retinal function using chromatic pupillography in retinitis pigmentosa and the relationship to electrically evoked phosphene thresholds.

    Science.gov (United States)

    Kelbsch, Carina; Maeda, Fumiatsu; Lisowska, Jolanta; Lisowski, Lukasz; Strasser, Torsten; Stingl, Krunoslav; Wilhelm, Barbara; Wilhelm, Helmut; Peters, Tobias

    2017-06-01

    To analyse pupil responses to specific chromatic stimuli in patients with advanced retinitis pigmentosa (RP) to ascertain whether chromatic pupillography can be used as an objective marker for residual retinal function. To examine correlations between parameters of the pupil response and the perception threshold of electrically evoked phosphenes. Chromatic pupillography was performed in 40 patients with advanced RP (visual acuity Chromatic pupillography demonstrated a significant decrease in outer retinal photoreceptor responses but a persisting and disinhibited intrinsic photosensitive retinal ganglion cell function in advanced RP. These phenomena may be useful as an objective marker for the efficacy of any interventional treatment for hereditary retinal diseases as well as for the selection of suitable patients for an electronic retinal implant. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  7. Ametropia, retinal anatomy, and OCT abnormality patterns in glaucoma. 2. Impacts of optic nerve head parameters

    Science.gov (United States)

    Baniasadi, Neda; Wang, Mengyu; Wang, Hui; Jin, Qingying; Elze, Tobias

    2017-12-01

    Clinicians use retinal nerve fiber layer thickness (RNFLT) measured by optical coherence tomography (OCT) as an adjunct to glaucoma diagnosis. Ametropia is accompanied by changes to the optic nerve head (ONH), which may affect how OCT machines mark RNFLT measurements as abnormal. These changes in abnormality patterns may bias glaucoma diagnosis. Here, we investigate the relationship between OCT abnormality patterns and the following ONH-related and ametropia-associated parameters on 421 eyes of glaucoma patients: optic disc tilt and torsion, central retinal vessel trunk location (CRVTL), and nasal and temporal retinal curvature adjacent to ONH, quantified as nasal/temporal slopes of the inner limiting membrane. We applied multivariate logistic regression with abnormality marks as regressands to 40,401 locations of the peripapillary region and generated spatial maps of locations of false positive/negative abnormality marks independent of glaucoma severity. Effects of torsion and temporal slope were negligible. The effect of tilt could be explained by covariation with ametropia. For CRVTL/nasal slope, abnormality pattern shifts at 7.2%/23.5% of the peripapillary region were detected, respectively, independent of glaucoma severity and ametropia. Therefore, CRVTL and nasal curvature should be included in OCT RNFLT norms. Our spatial location maps may aid clinicians to improve diagnostic accuracy.

  8. Retinal detachment in black South Africans

    African Journals Online (AJOL)

    low incidence of retinal detachment in black patients is not known. ... a retinal break. Predisposing factors include peripheral retinal degenerations, myopia, aphakia and trauma. Delay in presentation increases the difficulty in achieving adequate surgical ... On examination, note was taken of the visual acuity in both eyes, the ...

  9. Cold source vessel development for the advanced neutron source

    Energy Technology Data Exchange (ETDEWEB)

    Williams, P.T.; Lucas, A.T. [Oak Ridge National Lab., TN (United States)

    1995-09-01

    The Advanced Neutron Source (ANS), in its conceptual design phase at Oak Ridge National Laboratory (ORNL), will be a user-oriented neutron research facility that will produce the most intense flux of neutrons in the world. Among its many scientific applications, the productions of cold neutrons is a significant research mission for the ANS. The cold neutrons come from two independent cold sources positioned near the reactor core. Contained by an aluminum alloy vessel, each cold source is a 410 mm diameter sphere of liquid deuterium that functions both as a neutron moderator and a cryogenic coolant. With nuclear heating of the containment vessel and internal baffling, steady-state operation requires close control of the liquid deuterium flow near the vessel`s inner surface. Preliminary thermal-hydraulic analyses supporting the cold source design are being performed with multi-dimensional computational fluid dynamics simulations of the liquid deuterium flow and heat transfer. This paper presents the starting phase of a challenging program and describes the cold source conceptual design, the thermal-hydraulic feasibility studies of the containment vessel, and the future computational and experimental studies that will be used to verify the final design.

  10. Development of an automated chip culture system with integrated on-line monitoring for maturation culture of retinal pigment epithelial cells

    Directory of Open Access Journals (Sweden)

    Mee-Hae Kim

    2017-10-01

    Full Text Available In cell manufacturing, the establishment of a fully automated, microfluidic, cell culture system that can be used for long-term cell cultures, as well as for process optimization is highly desirable. This study reports the development of a novel chip bioreactor system that can be used for automated long-term maturation cultures of retinal pigment epithelial (RPE cells. The system consists of an incubation unit, a medium supply unit, a culture observation unit, and a control unit. In the incubation unit, the chip contains a closed culture vessel (2.5 mm diameter, working volume 9.1 μL, which can be set to 37 °C and 5% CO2, and uses a gas-permeable resin (poly- dimethylsiloxane as the vessel wall. RPE cells were seeded at 5.0 × 104 cells/cm2 and the medium was changed every day by introducing fresh medium using the medium supply unit. Culture solutions were stored either in the refrigerator or the freezer, and fresh medium was prepared before any medium change by warming to 37 °C and mixing. Automated culture was allowed to continue for 30 days to allow maturation of the RPE cells. This chip culture system allows for the long-term, bubble-free, culture of RPE cells, while also being able to observe cells in order to elucidate their cell morphology or show the presence of tight junctions. This culture system, along with an integrated on-line monitoring system, can therefore be applied to long-term cultures of RPE cells, and should contribute to process control in RPE cell manufacturing.

  11. Distribution of Different Sized Ocular Surface Vessels in Diabetics and Normal Individuals.

    Science.gov (United States)

    Banaee, Touka; Pourreza, Hamidreza; Doosti, Hassan; Abrishami, Mojtaba; Ehsaei, Asieh; Basiry, Mohsen; Pourreza, Reza

    2017-01-01

    To compare the distribution of different sized vessels using digital photographs of the ocular surface of diabetic and normal individuals. In this cross-sectional study, red-free conjunctival photographs of diabetic and normal individuals, aged 30-60 years, were taken under defined conditions and analyzed using a Radon transform-based algorithm for vascular segmentation. The image areas occupied by vessels (AOV) of different diameters were calculated. The main outcome measure was the distribution curve of mean AOV of different sized vessels. Secondary outcome measures included total AOV and standard deviation (SD) of AOV of different sized vessels. Two hundred and sixty-eight diabetic patients and 297 normal (control) individuals were included, differing in age (45.50 ± 5.19 vs. 40.38 ± 6.19 years, P distribution curves of mean AOV differed between patients and controls (smaller AOV for larger vessels in patients; P distribution curve of vessels compared to controls. Presence of diabetes mellitus is associated with contraction of larger vessels in the conjunctiva. Smaller vessels dilate with diabetic retinopathy. These findings may be useful in the photographic screening of diabetes mellitus and retinopathy.

  12. Prevalence of generalized retinal dystrophy in Denmark

    DEFF Research Database (Denmark)

    Bertelsen, Mette; Jensen, Hanne; Bregnhøj, Jesper F

    2014-01-01

    of this study was to examine the prevalence and diagnostic spectrum of generalized retinal dystrophy in the Danish population. METHODS: A population-based cross-sectional study with data from the Danish Retinitis Pigmentosa Registry that comprises all patients in Denmark with generalized retinal......PURPOSE: Generalized retinal dystrophy is a frequent cause of visual impairment and blindness in younger individuals and a subject of new clinical intervention trials. Nonetheless, there are few nation-wide population-based epidemiological data of generalized retinal dystrophy. The purpose...... and chorioretinal dystrophies from the 19th century to the present. Among 3076 registered cases, the primary diagnosis of generalized retinal dystrophy was assessed by chart review, including fundus photographs and electroretinograms. Demographic data on the Danish population were retrieved from Statistics Denmark...

  13. Dynamics of micro-bubble sonication inside a phantom vessel

    KAUST Repository

    Qamar, Adnan; Samtaney, Ravi; Bull, Joseph L.

    2013-01-01

    A model for sonicated micro-bubble oscillations inside a phantom vessel is proposed. The model is not a variant of conventional Rayleigh-Plesset equation and is obtained from reduced Navier-Stokes equations. The model relates the micro-bubble oscillation dynamics with geometric and acoustic parameters in a consistent manner. It predicts micro-bubble oscillation dynamics as well as micro-bubble fragmentation when compared to the experimental data. For large micro-bubble radius to vessel diameter ratios, predictions are damped, suggesting breakdown of inherent modeling assumptions for these cases. Micro-bubble response with acoustic parameters is consistent with experiments and provides physical insight to the micro-bubble oscillation dynamics.

  14. Dynamics of micro-bubble sonication inside a phantom vessel

    KAUST Repository

    Qamar, Adnan

    2013-01-10

    A model for sonicated micro-bubble oscillations inside a phantom vessel is proposed. The model is not a variant of conventional Rayleigh-Plesset equation and is obtained from reduced Navier-Stokes equations. The model relates the micro-bubble oscillation dynamics with geometric and acoustic parameters in a consistent manner. It predicts micro-bubble oscillation dynamics as well as micro-bubble fragmentation when compared to the experimental data. For large micro-bubble radius to vessel diameter ratios, predictions are damped, suggesting breakdown of inherent modeling assumptions for these cases. Micro-bubble response with acoustic parameters is consistent with experiments and provides physical insight to the micro-bubble oscillation dynamics.

  15. Clinical Results of Arteriovenous Fistulas Constructed Using Autologous Vessels in End-Stage Renal Disease Patients on Hemodialysis

    Directory of Open Access Journals (Sweden)

    Ki Tae Kim

    2018-04-01

    Full Text Available Background: For hemodialysis patients with end-stage renal disease (ESRD, it is important to construct an efficient vascular access with a superior patency rate. This study investigated the factors influencing the efficiency of arteriovenous fistulas (AVFs constructed using an autologous vessel and evaluated the necessity of ultrasonography as a preoperative tool for AVF construction. Methods: A retrospective analysis was performed of 250 patients in whom an AVF was constructed using an autologous vessel due to ESRD at our institution from January 2009 to April 2016. Results: The 1-, 3-, and 5-year patency rates for all subjects were 87.6%, 85.6%, and 84.4%, respectively. The patients who underwent a preoperative evaluation of their vessels via ultrasonography had better patency rates than those who did not. Superior patency rates were found in patients under 65 years of age or with an anastomotic vein diameter of 3 mm or more. The 1-year patency rate and the diameter of the anastomotic vein showed a positive relationship. Conclusion: Ultrasonography is strongly recommended for AVF construction, and efforts should be made to increase the patency rate in patients over 65. Superior clinical results can be expected when an AVF is made using an autologous vessel with an anastomotic vein diameter of at least 3 mm.

  16. Differences in Pre and Post Vascular Patterning Within Retinas from ISS Crew Members and Head-Down Tilt (HDT) Subjects by VESGEN Analysis

    Science.gov (United States)

    Murray, M. C.; Vizzeri, G.; Taibbi, G.; Mason, S. S.; Young, M.; Zanello, S. B.; Parsons-Wingerter, P.

    2018-01-01

    Accelerated research by NASA has investigated the significant risks incurred during long-duration missions in microgravity for Space Flight-Associated Neuro-ocular Syndrome (SANS, formerly known as Visual Impairments associated with Increased Intracranial Pressure, VIIP) [1]. For our study, NASA's VESsel GENeration Analysis (VESGEN) was used to investigate the role of retinal blood vessels in the etiology of SANS/VIIP. The response of retinal vessels to microgravity was evaluated in astronaut crew members pre and post flight to the International Space Station (ISS), and compared to the response of retinal vessels in healthy volunteers to 6deg head-down tilt during 70 days of bed rest (HDTBR). For the study, we are testing the hypothesis that long-term cephalad fluid shifts resulting in ocular and visual impairments are necessarily mediated in part by retinal blood vessels, and therefore are accompanied by structural adaptations of the vessels. METHODS: Vascular patterns in the retinas of crew members and HDTBR subjects extracted from 30deg infrared (IR) Heidelberg Spectralis images collected pre/postflight and pre/post HDTBR, respectively, were analyzed by VESGEN (patent pending). VESGEN is a mature, automated software developed as a research discovery tool for progressive vascular diseases in the retina and other tissues. The multi-parametric VESGEN analysis generates maps of branching arterial and venous trees quantified by parameters such as the fractal dimension (Df, a modern measure of vascular space-filling capacity), vessel diameters, and densities of vessel length and number classified into specific branching generations according to vascular physiological branching rules. The retrospective study approved by NASA's Institutional Review Board included the analysis of bilateral retinas in eight ISS crew members monitored by routine occupational surveillance and six HDTBR subjects (NASA FARU Campaign 11, for example). The VESGEN analysis was conducted in a

  17. Problems in Pressure Vessel Design and Manufacture

    Energy Technology Data Exchange (ETDEWEB)

    Hellstroem, O [Uddeholms AB, Degerfors (Sweden); Nilson, Ragnar [AB Atomenergi, Nykoeping (Sweden)

    1963-05-15

    The general desire by the power reactor process makers to increase power rating and their efforts to involve more advanced thermal behaviour and fuel handling facilities within the reactor vessels are accompanied by an increase in both pressure vessel dimensions and various difficulties in giving practical solutions of design materials and fabrication problems. In any section of this report it is emphasized that difficulties and problems already met with will meet again in the future vessels but then in modified forms and in many cases more pertinent than before. As for the increase in geometrical size it can be postulated that with use of better materials and adjusted fabrication methods the size problems can be taken proper care of. It seems likely that vessels of sufficient large diameter and height for the largest power output, which is judged as interesting in the next ten year period, can be built without developing totally new site fabrication technique. It is, however, supposed that such a fabrication technique will be feasible though at higher specific costs for the same quality requirements as obtained in shop fabrication. By the postulated use of more efficient vessel material with principally the same good features of easy fabrication in different stages such as preparation, welding, heat treatment etc as ordinary or slightly modified carbon steels the increase in wall thickness might be kept low. There exists, however, a development work to be done for low-alloy steels to prove their justified use in large reactor pressure vessels.

  18. Problems in Pressure Vessel Design and Manufacture

    International Nuclear Information System (INIS)

    Hellstroem, O.; Nilson, Ragnar

    1963-05-01

    The general desire by the power reactor process makers to increase power rating and their efforts to involve more advanced thermal behaviour and fuel handling facilities within the reactor vessels are accompanied by an increase in both pressure vessel dimensions and various difficulties in giving practical solutions of design materials and fabrication problems. In any section of this report it is emphasized that difficulties and problems already met with will meet again in the future vessels but then in modified forms and in many cases more pertinent than before. As for the increase in geometrical size it can be postulated that with use of better materials and adjusted fabrication methods the size problems can be taken proper care of. It seems likely that vessels of sufficient large diameter and height for the largest power output, which is judged as interesting in the next ten year period, can be built without developing totally new site fabrication technique. It is, however, supposed that such a fabrication technique will be feasible though at higher specific costs for the same quality requirements as obtained in shop fabrication. By the postulated use of more efficient vessel material with principally the same good features of easy fabrication in different stages such as preparation, welding, heat treatment etc as ordinary or slightly modified carbon steels the increase in wall thickness might be kept low. There exists, however, a development work to be done for low-alloy steels to prove their justified use in large reactor pressure vessels

  19. Clinically undetected retinal breaks causing retinal detachment: A review of options for management.

    Science.gov (United States)

    Gupta, Deepak; Ching, Jared; Tornambe, Paul E

    2017-08-12

    The successful detection of retinal breaks is a critical step in rhegmatogenous retinal detachment surgery in order to prevent persistent/recurrent retinal detachments. Not all retinal breaks causing retinal detachments are obvious. Retinal breaks may be obscured by opacities that are either anterior segment related, lens related, or posterior segment related. Rules to identify breaks based on subretinal fluid configuration are more difficult to apply in pseudophakic, aphakic, and scleral buckle encircled eyes-and in eyes with repeat detachments and those with proliferative vitreoretinopathy. Exudative detachments exhibit characteristic features and must be ruled out. A thorough clinical examination preoperatively is important even if a vitrectomy is planned. We review the incidence and causes of undetected breaks, along with preoperative/clinical issues that may hinder break detection. We review the literature with respect to investigative approaches and techniques that are available to the vitreoretinal surgeon when primary breaks remain clinically undetected during the preoperative examination. We broadly divide the surgical approaches into ones where the surgeon utilizes techniques to pursue actively a search for breaks versus adopting a purely speculative approach. Advantages and disadvantages of various techniques are appraised. Intuitively one might argue that an encircling scleral buckle combined with vitrectomy would give higher single operation success than pars plana vitrectomy alone because "undetected" retinal breaks would be addressed by a 360° plombage. We could not confirm this concept. Newer techniques, such as pars plana vitrectomy augmented with dye extrusion or endoscopic-assisted pars plana vitrectomy, show encouraging results. Technological advances such as intraoperative optical coherence tomography will also help to broaden the vitreoretinal surgeon's armamentarium. At this time, there is no gold standard in terms of the recommended

  20. Progesterone increases resistance of ophthalmic and central retinal arteries in climacteric women.

    Science.gov (United States)

    Souza, M A M De; Souza, B M De; Geber, S

    2013-04-01

    To evaluate the effect of a synthetic progestin on the vascular resistance of the ophthalmic and central retinal arteries in climacteric women, compared to placebo, using transorbital ultrasound with Doppler velocimetry. We performed a prospective, randomized, double-blinded, placebo-controlled study with 216 climacteric women. Subjects were randomly allocated to one of two groups: either the group receiving placebo (one pill/day for 30 days) (n = 108) or the group receiving progestin (5 mg medroxyprogesterone acetate/day for 30 days) (n = 108). Transorbital Doppler velocimetric ultrasound was performed, before and after treatment; we measured the pulsatility index, resistance index and systole/diastole ratio. The mean ages of the participants in the study group and the control group were 54 ± 6.2 years (range 48-59 years) and 55 ± 6.8 years (range 46-60 years), respectively. When we compared the effect of the progestin on the central retinal artery before and after treatment, we observed a significant increase after the treatment in all Doppler indices. The same was observed when we compared the effect of the progestin on the ophthalmic artery. In the group of women receiving placebo, the Doppler indices were similar before and after treatment. Our results demonstrate the existence of a progestogenic vasoconstrictive effect in the ophthalmic and central retinal arteries. As this study provides new data, the observed effect needs further investigations to better elucidate its extent. Moreover, our findings may be particularly useful to others interested in understanding the vascular dynamics of the cerebral vessels and to researchers running clinical trials related to hormone replacement therapy.

  1. Retinal vascular geometry and its association to microvascular complications in patients with type 1 diabetes

    DEFF Research Database (Denmark)

    Rasmussen, M L; Broe, Rebecca; Frydkjaer-Olsen, Ulrik

    2017-01-01

    PURPOSE: To examine associations between retinal vascular geometry (tortuosity, branching coefficient [BC] and length-diameter ratio [LDR]) and diabetic proliferative retinopathy (PDR), nephropathy, and peripheral neuropathy in patients with type 1 diabetes mellitus (T1DM). METHODS: A cohort...... of patients with T1DM participated in a clinical examination in 2011. Blood and urine analyses were done and retinal images taken. PDR was defined as Early Treatment Diabetic Retinopathy Study level 61 or above, nephropathy as albumin-creatinin ratio ≥300 mg/g, and neuropathy as vibration perception threshold.......8% were male. Prevalence of PDR, nephropathy, and neuropathy were 26.5%, 6.8%, and 10.1% , respectively. Patients with increased arteriolar BC had a higher risk of nephropathy (OR: 3.10, 95% CI: [1.01-9.54]). Patients with increased venular BC had a higher risk of neuropathy (OR: 2.11, 95% CI: [1...

  2. Reliability of Using Retinal Vascular Fractal Dimension as a Biomarker in the Diabetic Retinopathy Detection.

    Science.gov (United States)

    Huang, Fan; Dashtbozorg, Behdad; Zhang, Jiong; Bekkers, Erik; Abbasi-Sureshjani, Samaneh; Berendschot, Tos T J M; Ter Haar Romeny, Bart M

    2016-01-01

    The retinal fractal dimension (FD) is a measure of vasculature branching pattern complexity. FD has been considered as a potential biomarker for the detection of several diseases like diabetes and hypertension. However, conflicting findings were found in the reported literature regarding the association between this biomarker and diseases. In this paper, we examine the stability of the FD measurement with respect to (1) different vessel annotations obtained from human observers, (2) automatic segmentation methods, (3) various regions of interest, (4) accuracy of vessel segmentation methods, and (5) different imaging modalities. Our results demonstrate that the relative errors for the measurement of FD are significant and FD varies considerably according to the image quality, modality, and the technique used for measuring it. Automated and semiautomated methods for the measurement of FD are not stable enough, which makes FD a deceptive biomarker in quantitative clinical applications.

  3. Retinal findings in membranoproliferative glomerulonephritis

    Directory of Open Access Journals (Sweden)

    Ahmad M. Mansour

    2017-09-01

    Conclusions and importance: Drusen remain the ocular stigmata for MPGN occuring at an early age. The retinal disease is progressive with gradual thickening of Bruch's membrane and occurrence of retinal pigment epithelium detachment.

  4. Retinal detachment in paediatric patients

    International Nuclear Information System (INIS)

    Zafar, S. N.; Qureshi, N.; Azad, N.; Khan, A.

    2013-01-01

    Objective: To assess the causes of retinal detachment in children and the various operative procedures requiring vitreoretinal surgical intervention for the same. Study Design: Case series. Place and Duration of Study: Department of Ophthalmology, Al-Shifa Trust Eye Hospital, Rawalpindi, from January 2006 to May 2009. Methodology: A total of 281 eyes of 258 patients, (aged 0 - 18 years) who underwent vitreo-retinal surgical intervention for retinal detachment were included. Surgical log was searched for the type of retinal detachment and its causes. Frequencies of various interventions done in these patients viz. vitrectomy, scleral buckle, use of tamponading agents, laser photocoagulation and cryotherapy were noted. Results were described as descriptive statistics. Results: Myopia was the cause in 62 (22.1%) and trauma in 51 (18.1%) of the eyes. Total retinal detachment (RD) was treated in 94 (33.5%) eyes, sub total RD in 36 (12.8%), recurrent RD in 32 (11.4%), giant retinal tear in 28 (10%), tractional RD in 15 (5.3%) and exudative RD in 2 (0.7%). Prophylactic laser or cryotherapy was applied in 74 (26.3%) of the eyes. Pars plana vitrectomy (PPV) was carried out in 159 (56.6%) eyes while scleral buckle procedure was done in 129 (45.9%) eyes. Silicon oil was used in 149 (53%), perfluorocarbon liquid in 32 (11.4%) and gas tamponade in 20 (7.1%) eyes. Conclusion: The most common cause of retinal detachment in paediatric patients was myopia, followed by trauma. Total RD was more common as compared to the other types. The most common procedure adopted was pars plana vitrectomy followed by scleral buckle procedure. (author)

  5. Retinal Prosthesis System for Advanced Retinitis Pigmentosa: A Health Technology Assessment Update

    Science.gov (United States)

    Lee, Christine; Tu, Hong Anh; Wells, David; Holubowich, Corinne

    2017-01-01

    Background Retinitis pigmentosa is a group of inherited disorders characterized by the degeneration of the photoreceptors in the retina, resulting in progressive vision loss. The Argus II system is designed to restore partial functional vision in patients with profound vision loss from advanced retinitis pigmentosa. At present, it is the only treatment option approved by Health Canada for this patient population. In June 2016, Health Quality Ontario published a health technology assessment of the Argus II retinal prosthesis system for patients with advanced retinitis pigmentosa. Based on that assessment, the Ontario Health Technology Advisory Committee recommended against publicly funding the Argus II system for this population. It also recommended that Health Quality Ontario re-evaluate the evidence in 1 year. The objective of this report was to examine new evidence published since the 2016 health technology assessment. Methods We completed a health technology assessment, which included an evaluation of clinical benefits and harms, value for money, and patient preferences related to the Argus II system. We performed a systematic literature search for studies published since the 2016 Argus II health technology assessment. We developed a Markov decision-analytic model to assess the cost-effectiveness of the Argus II system compared with standard care, and we calculated incremental cost-effectiveness ratios over a 20-year time horizon. We also conducted a five-year budget impact analysis. Finally, we interviewed people with retinitis pigmentosa about their lived experience with vision loss, and with the Argus II system. Results Four publications from one multicentre international study were included in the clinical review. Patients showed significant improvements in visual function and functional outcomes with the Argus II system, and these outcomes were sustained up to a 5-year follow-up (moderate quality of evidence). The safety profile was generally acceptable. In

  6. Cerebro-afferent vessel and pupillary basal diameter variation induced by stomatognathic trigeminal proprioception: a case report.

    Science.gov (United States)

    De Cicco, Vincenzo

    2012-09-03

    A patient affected by asymmetric hemodynamics of cerebro-afferent vessels underwent duplex color scanner investigations in occlusal proprioceptive un- and rebalance conditions. Pupillometric video-oculographic examinations were performed in order to spot connected trigeminal proprioceptive motor patterns able to interfere on sympathetic autonomic activity. The aim of this case report is to verify if involuntary jaw closing during swallowing, executed in unbalance and rebalance myoelectric activity, would be able to modify cerebral hemodynamics. A 56-year-old Caucasian Italian woman affected by asymmetric blood flow of cerebro-afferent vessels underwent an electromyographic investigation of her occlusal muscles in order to assess their occlusal functional balance. The extreme asymmetry of myoelectric activity in dental occlusion evidenced by electromyographic values suggested the rebalancing of the functions of occlusal muscles through concurrent transcutaneous stimulation of the trigeminal nerve supra- and submandibular motor branches. The above-mentioned method allowed the detection of a symmetric craniomandibular muscular relation that can be kept constant through the use of a cusp bite modeled on the inferior dental arch: called orthotic-syntropic bite for its peculiar use of electrostimulation. A few days later, the patient underwent a duplex color scanner investigation and pupillometric video-oculographic examinations in occlusal unbalance and rebalance conditions. A comparative data analysis showed that an unbalanced dental occlusal function may represent an interferential pattern on cerebral hemodynamics velocity and pupillometric evaluations have proved useful both in the analysis of locus coeruleus functional modalities and as a diagnostic tool in the assessment of pathologies involving locus coeruleus and autonomic systems. The inclusion of myoelectric masseter examinations can be useful in patients with asymmetric hemodynamics of cerebro

  7. Imaging of Dual Ophthalmic Arteries: Identification of the Central Retinal Artery

    Directory of Open Access Journals (Sweden)

    Louise Louw

    2014-01-01

    Full Text Available Identification of the origin of the central retinal artery (CRA is imperative in tailoring angiographic studies to resolve a given clinical problem. A case with dual ophthalmic arteries (OAs, characterized by different origins and distinct branching patterns, is documented for training purposes. Pre-clinical diagnosis of a 9-year-old child who presented with a sharp wire in the left-side eyeball was primarily corneal laceration. For imaging, a selected six-vessel angiographic study with the transfemoral approach was performed. Embolization was not required and the wire could be successfully removed. Right-side OA anatomy was normal, while left-side dual OAs with external carotid artery (ECA and internal carotid artery (ICA origins were seen. The case presented with a left-side meningo-ophthalmic artery (M-OA anomaly via the ECA, marked by a middle meningeal artery (MMA (origin: Maxillary artery; course: Through foramen spinosum with normal branches (i.e. anterior and posterior branches, and an OA variant (course: Through superior orbital fissure with a distinct orbital branching pattern. A smaller OA (origin: ICA; course: Through optic foramen with a distinct ocular branching pattern presented with the central retinal artery (CRA. The presence of the dual OAs and the M-OA anomaly can be explained by disturbed evolutionary changes of the primitive OA and stapedial artery during development. The surgical interventionist must be aware of dual OAs and M-OA anomalies with branching pattern variations on retinal supply, because of dangerous extracranial-intracranial anastomotic connections. It is of clinical significance that the origin of the CRA from the ICA or ECA must be determined to avoid complications to the vision.

  8. Stem Cell-Based Therapeutic Applications in Retinal Degenerative Diseases.

    OpenAIRE

    Huang Yiming; Enzmann Volker; Ildstad Suzanne T

    2011-01-01

    Retinal degenerative diseases that target photoreceptors or the adjacent retinal pigment epithelium (RPE) affect millions of people worldwide. Retinal degeneration (RD) is found in many different forms of retinal diseases including retinitis pigmentosa (RP), age-related macular degeneration (AMD), diabetic retinopathy, cataracts, and glaucoma. Effective treatment for retinal degeneration has been widely investigated. Gene-replacement therapy has been shown to improve visual function in inheri...

  9. Effects of irradiation on renal vessels of rabbits

    International Nuclear Information System (INIS)

    Hanayama, Hirotaka

    1982-01-01

    The male rabbits weighing approximately 3 kg were divided into two groups: one group received irradiation to the left kidney through 6 x 4 cm field size with doses of 5 Gy, while the other group was irradiated with 50 Gy. The vessel casts were observed using the injection replica scanning electron microscopic method. In 50 Gy irradiated group, the surface of blood vessel's lumen became irregular with a decrease in the number of glomeruli at 5 days. Partial narrowing was also seen in the cortex and glomerular vessels. The number of glomeruli decreased by 48% one week later and 90% 4 weeks later. The cortex vessels progressively narrowed, and irregularity of the net-like structure was also observed. Similarly, a decrease in the number of glomeruli and partial narrowing of the blood vessels were seen at 5 days on the nonirradiated side, but the damage was considerably less than that on the irradiated side. In the 5 Gy irradiated group, a decrease in the number of glomeruli was seen 5 days later and it became 71% 5 days later and 81% one week later. It returned to 95% 4 weeks later. No changes whatsoever were seen in the non-irradiated side after 4 weeks and changes in the number of glomeruli were not observed. The vasculation of medulla showed no changes in the 50 Gy or the 5 Gy irradiated group. There were seen no significant changes in the blood vessel diameter. (J.P.N.)

  10. Retinal Cell Degeneration in Animal Models

    Directory of Open Access Journals (Sweden)

    Masayuki Niwa

    2016-01-01

    Full Text Available The aim of this review is to provide an overview of various retinal cell degeneration models in animal induced by chemicals (N-methyl-d-aspartate- and CoCl2-induced, autoimmune (experimental autoimmune encephalomyelitis, mechanical stress (optic nerve crush-induced, light-induced and ischemia (transient retinal ischemia-induced. The target regions, pathology and proposed mechanism of each model are described in a comparative fashion. Animal models of retinal cell degeneration provide insight into the underlying mechanisms of the disease, and will facilitate the development of novel effective therapeutic drugs to treat retinal cell damage.

  11. Morphology and Topography of Retinal Pericytes in the Living Mouse Retina Using In Vivo Adaptive Optics Imaging and Ex Vivo Characterization

    Science.gov (United States)

    Schallek, Jesse; Geng, Ying; Nguyen, HoanVu; Williams, David R.

    2013-01-01

    Purpose. To noninvasively image retinal pericytes in the living eye and characterize NG2-positive cell topography and morphology in the adult mouse retina. Methods. Transgenic mice expressing fluorescent pericytes (NG2, DsRed) were imaged using a two-channel, adaptive optics scanning laser ophthalmoscope (AOSLO). One channel imaged vascular perfusion with near infrared light. A second channel simultaneously imaged fluorescent retinal pericytes. Mice were also imaged using wide-field ophthalmoscopy. To confirm in vivo imaging, five eyes were enucleated and imaged in flat mount with conventional fluorescent microscopy. Cell topography was quantified relative to the optic disc. Results. We observed strong DsRed fluorescence from NG2-positive cells. AOSLO revealed fluorescent vascular mural cells enveloping all vessels in the living retina. Cells were stellate on larger venules, and showed banded morphology on arterioles. NG2-positive cells indicative of pericytes were found on the smallest capillaries of the retinal circulation. Wide-field SLO enabled quick assessment of NG2-positive distribution, but provided insufficient resolution for cell counts. Ex vivo microscopy showed relatively even topography of NG2-positive capillary pericytes at eccentricities more than 0.3 mm from the optic disc (515 ± 94 cells/mm2 of retinal area). Conclusions. We provide the first high-resolution images of retinal pericytes in the living animal. Subcellular resolution enabled morphological identification of NG2-positive cells on capillaries showing classic features and topography of retinal pericytes. This report provides foundational basis for future studies that will track and quantify pericyte topography, morphology, and function in the living retina over time, especially in the progression of microvascular disease. PMID:24150762

  12. Prophylactic treatment of retinal breaks

    DEFF Research Database (Denmark)

    Blindbæk, Søren Leer; Grauslund, Jakob

    2015-01-01

    Prophylactic treatment of retinal breaks has been examined in several studies and reviews, but so far, no studies have successfully applied a systematic approach. In the present systematic review, we examined the need of follow-up after posterior vitreous detachment (PVD) - diagnosed by slit...... published before 2012. Four levels of screening identified 13 studies suitable for inclusion in this systematic review. No meta-analysis was conducted as no data suitable for statistical analysis were identified. In total, the initial examination after symptomatic PVD identified 85-95% of subsequent retinal......-47% of cases, respectively. The cumulated incidence of RRD despite prophylactic treatment was 2.1-8.8%. The findings in this review suggest that follow-up after symptomatic PVD is only necessary in cases of incomplete retinal examination at presentation. Prophylactic treatment of symptomatic retinal breaks...

  13. Vascular diameter measurement in CT angiography: comparison of model-based iterative reconstruction and standard filtered back projection algorithms in vitro.

    Science.gov (United States)

    Suzuki, Shigeru; Machida, Haruhiko; Tanaka, Isao; Ueno, Eiko

    2013-03-01

    The purpose of this study was to evaluate the performance of model-based iterative reconstruction (MBIR) in measurement of the inner diameter of models of blood vessels and compare performance between MBIR and a standard filtered back projection (FBP) algorithm. Vascular models with wall thicknesses of 0.5, 1.0, and 1.5 mm were scanned with a 64-MDCT unit and densities of contrast material yielding 275, 396, and 542 HU. Images were reconstructed images by MBIR and FBP, and the mean diameter of each model vessel was measured by software automation. Twenty separate measurements were repeated for each vessel, and variance among the repeated measures was analyzed for determination of measurement error. For all nine model vessels, CT attenuation profiles were compared along a line passing through the luminal center on axial images reconstructed with FBP and MBIR, and the 10-90% edge rise distances at the boundary between the vascular wall and the lumen were evaluated. For images reconstructed with FBP, measurement errors were smallest for models with 1.5-mm wall thickness, except those filled with 275-HU contrast material, and errors grew as the density of the contrast material decreased. Measurement errors with MBIR were comparable to or less than those with FBP. In CT attenuation profiles of images reconstructed with MBIR, the 10-90% edge rise distances at the boundary between the lumen and vascular wall were relatively short for each vascular model compared with those of the profile curves of FBP images. MBIR is better than standard FBP for reducing reconstruction blur and improving the accuracy of diameter measurement at CT angiography.

  14. Comparative analysis of methods for extracting vessel network on breast MRI images

    Science.gov (United States)

    Gaizer, Bence T.; Vassiou, Katerina G.; Lavdas, Eleftherios; Arvanitis, Dimitrios L.; Fezoulidis, Ioannis V.; Glotsos, Dimitris T.

    2017-11-01

    Digital processing of MRI images aims to provide an automatized diagnostic evaluation of regular health screenings. Cancerous lesions are proven to cause an alteration in the vessel structure of the diseased organ. Currently there are several methods used for extraction of the vessel network in order to quantify its properties. In this work MRI images (Signa HDx 3.0T, GE Healthcare, courtesy of University Hospital of Larissa) of 30 female breasts were subjected to three different vessel extraction algorithms to determine the location of their vascular network. The first method is an experiment to build a graph over known points of the vessel network; the second algorithm aims to determine the direction and diameter of vessels at these points; the third approach is a seed growing algorithm, spreading selection to neighbors of the known vessel pixels. The possibilities shown by the different methods were analyzed, and quantitative measurements were performed. The data provided by these measurements showed no clear correlation with the presence or malignancy of tumors, based on the radiological diagnosis of skilled physicians.

  15. Diaphragmatic lymphatic vessel behavior during local skeletal muscle contraction.

    Science.gov (United States)

    Moriondo, Andrea; Solari, Eleonora; Marcozzi, Cristiana; Negrini, Daniela

    2015-02-01

    The mechanism through which the stresses developed in the diaphragmatic tissue during skeletal muscle contraction sustain local lymphatic function was studied in 10 deeply anesthetized, tracheotomized adult Wistar rats whose diaphragm was exposed after thoracotomy. To evaluate the direct effect of skeletal muscle contraction on the hydraulic intraluminal lymphatic pressures (Plymph) and lymphatic vessel geometry, the maximal contraction of diaphragmatic fibers adjacent to a lymphatic vessel was elicited by injection of 9.2 nl of 1 M KCl solution among diaphragmatic fibers while Plymph was recorded through micropuncture and vessel geometry via stereomicroscopy video recording. In lymphatics oriented perpendicularly to the longitudinal axis of muscle fibers and located at skeletal muscle contraction (Dmc) decreased to 61.3 ± 1.4% of the precontraction value [resting diameter (Drest)]; however, if injection was at >900 μm from the vessel, Dmc enlarged to 131.1 ± 2.3% of Drest. In vessels parallel to muscle fibers, Dmc increased to 122.8 ± 2.9% of Drest. During contraction, Plymph decreased as much as 22.5 ± 2.6 cmH2O in all submesothelial superficial vessels, whereas it increased by 10.7 ± 5.1 cmH2O in deeper vessels running perpendicular to contracting muscle fibers. Hence, the three-dimensional arrangement of the diaphragmatic lymphatic network seems to be finalized to efficiently exploit the stresses exerted by muscle fibers during the contracting inspiratory phase to promote lymph formation in superficial submesothelial lymphatics and its further propulsion in deeper intramuscular vessels. Copyright © 2015 the American Physiological Society.

  16. Transcorneal Electrical Stimulation Therapy for Retinal Disease

    Science.gov (United States)

    2012-05-03

    Retinitis Pigmentosa; Macula Off; Primary Open Angle Glaucoma; Hereditary Macular Degeneration; Treated Retina Detachment; Retinal Artery Occlusion; Retinal Vein Occlusion; Non-Arthritic-Anterior-Ischemic Optic-Neuropathy; Hereditary Autosomal Dominant Optic Atrophy; Dry Age Related Macular Degeneration; Ischemic Macula Edema

  17. Transplantation of rat embryonic stem cell-derived retinal progenitor cells preserves the retinal structure and function in rat retinal degeneration.

    Science.gov (United States)

    Qu, Zepeng; Guan, Yuan; Cui, Lu; Song, Jian; Gu, Junjie; Zhao, Hanzhi; Xu, Lei; Lu, Lixia; Jin, Ying; Xu, Guo-Tong

    2015-11-09

    Degenerative retinal diseases like age-related macular degeneration (AMD) are the leading cause of blindness. Cell transplantation showed promising therapeutic effect for such diseases, and embryonic stem cell (ESC) is one of the sources of such donor cells. Here, we aimed to generate retinal progenitor cells (RPCs) from rat ESCs (rESCs) and to test their therapeutic effects in rat model. The rESCs (DA8-16) were cultured in N2B27 medium with 2i, and differentiated to two types of RPCs following the SFEBq method with modifications. For rESC-RPC1, the cells were switched to adherent culture at D10, while for rESC-RPC2, the suspension culture was maintained to D14. Both RPCs were harvested at D16. Primary RPCs were obtained from P1 SD rats, and some of them were labeled with EGFP by infection with lentivirus. To generate Rax::EGFP knock-in rESC lines, TALENs were engineered to facilitate homologous recombination in rESCs, which were cotransfected with the targeting vector and TALEN vectors. The differentiated cells were analyzed with live image, immunofluorescence staining, flow cytometric analysis, gene expression microarray, etc. RCS rats were used to mimic the degeneration of retina and test the therapeutic effects of subretinally transplanted donor cells. The structure and function of retina were examined. We established two protocols through which two types of rESC-derived RPCs were obtained and both contained committed retina lineage cells and some neural progenitor cells (NPCs). These rESC-derived RPCs survived in the host retinas of RCS rats and protected the retinal structure and function in early stage following the transplantation. However, the glia enriched rESC-RPC1 obtained through early and longer adherent culture only increased the b-wave amplitude at 4 weeks, while the longer suspension culture gave rise to evidently neuronal differentiation in rESC-RPC2 which significantly improved the visual function of RCS rats. We have successfully differentiated

  18. The impact of vessel size on vulnerability curves: data and models for within-species variability in saplings of aspen, Populus tremuloides Michx.

    Science.gov (United States)

    Cai, Jing; Tyree, Melvin T

    2010-07-01

    The objective of this study was to quantify the relationship between vulnerability to cavitation and vessel diameter within a species. We measured vulnerability curves (VCs: percentage loss hydraulic conductivity versus tension) in aspen stems and measured vessel-size distributions. Measurements were done on seed-grown, 4-month-old aspen (Populus tremuloides Michx) grown in a greenhouse. VCs of stem segments were measured using a centrifuge technique and by a staining technique that allowed a VC to be constructed based on vessel diameter size-classes (D). Vessel-based VCs were also fitted to Weibull cumulative distribution functions (CDF), which provided best-fit values of Weibull CDF constants (c and b) and P(50) = the tension causing 50% loss of hydraulic conductivity. We show that P(50) = 6.166D(-0.3134) (R(2) = 0.995) and that b and 1/c are both linear functions of D with R(2) > 0.95. The results are discussed in terms of models of VCs based on vessel D size-classes and in terms of concepts such as the 'pit area hypothesis' and vessel pathway redundancy.

  19. Laparoscopic prototype for optical sealing of renal blood vessels

    Science.gov (United States)

    Hardy, Luke A.; Hutchens, Thomas C.; Larson, Eric R.; Gonzalez, David A.; Chang, Chun-Hung; Nau, William H.; Fried, Nathaniel M.

    2017-02-01

    Energy-based, radiofrequency and ultrasonic devices provide rapid sealing of blood vessels during laparoscopic procedures. We are exploring infrared lasers as an alternative for vessel sealing with less collateral thermal damage. Previous studies demonstrated vessel sealing in an in vivo porcine model using a 1470-nm laser. However, the initial prototype was designed for open surgery and featured tissue clasping and light delivery mechanisms incompatible with laparoscopic surgery. In this study, a laparoscopic prototype similar to devices in surgical use was developed, and tests were conducted on porcine renal blood vessels. The 5-mm-OD prototype featured a traditional Maryland jaw configuration. Laser energy was delivered through a 550-μm-core fiber and side-delivery from the lower jaw, with beam dimensions of 18-mm-length x 1.2-mm-width. The 1470-nm diode laser delivered 68 W with 3 s activation time. A total of 69 porcine renal vessels with mean diameter of 3.3 +/- 1.7 mm were tested, ex vivo. Vessels smaller than 5 mm were consistently sealed (48/51) with burst pressures greater than malignant hypertension blood pressure (180 mmHg), averaging 1038 +/- 474 mmHg. Vessels larger than 5 mm were not consistently sealed (6/18), yielding burst pressures of only 174 +/- 221 mmHg. Seal width, thermal damage zone, and thermal spread averaged 1.7 +/- 0.8, 3.4 +/- 0.7, and 1.0 +/- 0.4 mm. A novel optical laparoscopic prototype with 5-mm- OD shaft integrated within a standard Maryland jaw design consistently sealed vessels less than 5 mm with minimal thermal spread. Further in vivo studies are planned to test performance across a variety of vessels and tissues.

  20. Retinal Structure Measurements as Inclusion Criteria for Stem Cell-Based Therapies of Retinal Degenerations.

    Science.gov (United States)

    Jacobson, Samuel G; Matsui, Rodrigo; Sumaroka, Alexander; Cideciyan, Artur V

    2016-04-01

    We reviewed and illustrated the most optimal retinal structural measurements to make in stem cell clinical trials. Optical coherence tomography (OCT) and autofluorescence (AF) imaging were used to evaluate patients with severe visual loss from nonsyndromic and syndromic retinitis pigmentosa (RP), ABCA4-Stargardt disease, and nonneovascular age-related macular degeneration (AMD). Outer nuclear layer (ONL), rod outer segment (ROS) layer, inner retina, ganglion cell layer (GCL), and nerve fiber layer (NFL) thicknesses were quantified. All patients had severely reduced visual acuities. Retinitis pigmentosa patients had limited visual fields; maculopathy patients had central scotomas with retained peripheral function. For the forms of RP illustrated, there was detectable albeit severely reduced ONL across the scanned retina, and normal or hyperthick GCL and NFL. Maculopathy patients had no measurable ONL centrally; it became detectable with eccentricity. Some maculopathy patients showed unexpected GCL losses. Autofluorescence imaging illustrated central losses of RPE integrity. A hypothetical scheme to relate patient data with different phases of retinal remodeling in animal models of retinal degeneration was presented. Stem cell science is advancing, but it is not too early to open the discussion of criteria for patient selection and monitoring. Available clinical tools, such as OCT and AF imaging, can provide inclusion/exclusion criteria and robust objective outcomes. Accepting that early trials may not lead to miraculous cures, we should be prepared to know why-scientifically and clinically-so we can improve subsequent trials. We also must determine if retinal remodeling is an impediment to efficacy.

  1. Influence of Clinical Factors and Magnification Correction on Normal Thickness Profiles of Macular Retinal Layers Using Optical Coherence Tomography

    Science.gov (United States)

    Higashide, Tomomi; Ohkubo, Shinji; Hangai, Masanori; Ito, Yasuki; Shimada, Noriaki; Ohno-Matsui, Kyoko; Terasaki, Hiroko; Sugiyama, Kazuhisa; Chew, Paul; Li, Kenneth K. W.; Yoshimura, Nagahisa

    2016-01-01

    Purpose To identify the factors which significantly contribute to the thickness variabilities in macular retinal layers measured by optical coherence tomography with or without magnification correction of analytical areas in normal subjects. Methods The thickness of retinal layers {retinal nerve fiber layer (RNFL), ganglion cell layer plus inner plexiform layer (GCLIPL), RNFL plus GCLIPL (ganglion cell complex, GCC), total retina, total retina minus GCC (outer retina)} were measured by macular scans (RS-3000, NIDEK) in 202 eyes of 202 normal Asian subjects aged 20 to 60 years. The analytical areas were defined by three concentric circles (1-, 3- and 6-mm nominal diameters) with or without magnification correction. For each layer thickness, a semipartial correlation (sr) was calculated for explanatory variables including age, gender, axial length, corneal curvature, and signal strength index. Results Outer retinal thickness was significantly thinner in females than in males (sr2, 0.07 to 0.13) regardless of analytical areas or magnification correction. Without magnification correction, axial length had a significant positive sr with RNFL (sr2, 0.12 to 0.33) and a negative sr with GCLIPL (sr2, 0.22 to 0.31), GCC (sr2, 0.03 to 0.17), total retina (sr2, 0.07 to 0.17) and outer retina (sr2, 0.16 to 0.29) in multiple analytical areas. The significant sr in RNFL, GCLIPL and GCC became mostly insignificant following magnification correction. Conclusions The strong correlation between the thickness of inner retinal layers and axial length appeared to result from magnification effects. Outer retinal thickness may differ by gender and axial length independently of magnification correction. PMID:26814541

  2. Influence of Clinical Factors and Magnification Correction on Normal Thickness Profiles of Macular Retinal Layers Using Optical Coherence Tomography.

    Directory of Open Access Journals (Sweden)

    Tomomi Higashide

    Full Text Available To identify the factors which significantly contribute to the thickness variabilities in macular retinal layers measured by optical coherence tomography with or without magnification correction of analytical areas in normal subjects.The thickness of retinal layers {retinal nerve fiber layer (RNFL, ganglion cell layer plus inner plexiform layer (GCLIPL, RNFL plus GCLIPL (ganglion cell complex, GCC, total retina, total retina minus GCC (outer retina} were measured by macular scans (RS-3000, NIDEK in 202 eyes of 202 normal Asian subjects aged 20 to 60 years. The analytical areas were defined by three concentric circles (1-, 3- and 6-mm nominal diameters with or without magnification correction. For each layer thickness, a semipartial correlation (sr was calculated for explanatory variables including age, gender, axial length, corneal curvature, and signal strength index.Outer retinal thickness was significantly thinner in females than in males (sr2, 0.07 to 0.13 regardless of analytical areas or magnification correction. Without magnification correction, axial length had a significant positive sr with RNFL (sr2, 0.12 to 0.33 and a negative sr with GCLIPL (sr2, 0.22 to 0.31, GCC (sr2, 0.03 to 0.17, total retina (sr2, 0.07 to 0.17 and outer retina (sr2, 0.16 to 0.29 in multiple analytical areas. The significant sr in RNFL, GCLIPL and GCC became mostly insignificant following magnification correction.The strong correlation between the thickness of inner retinal layers and axial length appeared to result from magnification effects. Outer retinal thickness may differ by gender and axial length independently of magnification correction.

  3. Influence of Clinical Factors and Magnification Correction on Normal Thickness Profiles of Macular Retinal Layers Using Optical Coherence Tomography.

    Science.gov (United States)

    Higashide, Tomomi; Ohkubo, Shinji; Hangai, Masanori; Ito, Yasuki; Shimada, Noriaki; Ohno-Matsui, Kyoko; Terasaki, Hiroko; Sugiyama, Kazuhisa; Chew, Paul; Li, Kenneth K W; Yoshimura, Nagahisa

    2016-01-01

    To identify the factors which significantly contribute to the thickness variabilities in macular retinal layers measured by optical coherence tomography with or without magnification correction of analytical areas in normal subjects. The thickness of retinal layers {retinal nerve fiber layer (RNFL), ganglion cell layer plus inner plexiform layer (GCLIPL), RNFL plus GCLIPL (ganglion cell complex, GCC), total retina, total retina minus GCC (outer retina)} were measured by macular scans (RS-3000, NIDEK) in 202 eyes of 202 normal Asian subjects aged 20 to 60 years. The analytical areas were defined by three concentric circles (1-, 3- and 6-mm nominal diameters) with or without magnification correction. For each layer thickness, a semipartial correlation (sr) was calculated for explanatory variables including age, gender, axial length, corneal curvature, and signal strength index. Outer retinal thickness was significantly thinner in females than in males (sr2, 0.07 to 0.13) regardless of analytical areas or magnification correction. Without magnification correction, axial length had a significant positive sr with RNFL (sr2, 0.12 to 0.33) and a negative sr with GCLIPL (sr2, 0.22 to 0.31), GCC (sr2, 0.03 to 0.17), total retina (sr2, 0.07 to 0.17) and outer retina (sr2, 0.16 to 0.29) in multiple analytical areas. The significant sr in RNFL, GCLIPL and GCC became mostly insignificant following magnification correction. The strong correlation between the thickness of inner retinal layers and axial length appeared to result from magnification effects. Outer retinal thickness may differ by gender and axial length independently of magnification correction.

  4. Elliptical local vessel density: a fast and robust quality metric for retinal images

    OpenAIRE

    Giancardo, L.; Abramoff, M.D.; Chaum, E.; Karnowski, T.P.; Meriaudeau, F.; Tobin, K.W.

    2008-01-01

    A great effort of the research community is geared towards the creation of an automatic screening system able to promptly detect diabetic retinopathy with the use of fundus cameras. In addition, there are some documented approaches for automatically judging the image quality. We propose a new set of features independent of field of view or resolution to describe the morphology of the patient's vessels. Our initial results suggest that these features can be used to estimate the image quality i...

  5. Vessel network detection using contour evolution and color components

    Energy Technology Data Exchange (ETDEWEB)

    Ushizima, Daniela; Medeiros, Fatima; Cuadros, Jorge; Martins, Charles

    2011-06-22

    Automated retinal screening relies on vasculature segmentation before the identification of other anatomical structures of the retina. Vasculature extraction can also be input to image quality ranking, neovascularization detection and image registration, among other applications. There is an extensive literature related to this problem, often excluding the inherent heterogeneity of ophthalmic clinical images. The contribution of this paper relies on an algorithm using front propagation to segment the vessel network. The algorithm includes a penalty in the wait queue on the fast marching heap to minimize leakage of the evolving interface. The method requires no manual labeling, a minimum number of parameters and it is capable of segmenting color ocular fundus images in real scenarios, where multi-ethnicity and brightness variations are parts of the problem.

  6. Safety of iPhone retinal photography.

    Science.gov (United States)

    Hong, Sheng Chiong; Wynn-Williams, Giles; Wilson, Graham

    2017-04-01

    With the advancement in mobile technology, smartphone retinal photography is becoming a popular practice. However, there is limited information about the safety of the latest smartphones used for retinal photography. This study aims to determine the photobiological risk of iPhone 6 and iPhone 6 plus when used in conjunction with a 20Diopter condensing lens for retinal photography. iPhone 6 and iPhone 6 plus (Apple, Cupertino, CA) were used in this study. The geometrical setup of the study was similar to the indirect ophthalmoscopy technique. The phone was set up at one end of the bench with its flash turned on at maximal brightness; a 20 Dioptre lens was placed 15 cm away from the phone. The light that passes through the lens was measured with a spectroradiometer and an illuminance probe at the other end to determine the spectral profile, spatial irradiance, radiant power emitted by the phone's flash. Trigonometric and lens formula were applied to determine the field of view and retinal surface in order to determine the weighted retinal irradiance and weighted retinal radiant exposure. Taking ocular transmission and the distribution of the beam's spatial irradiance into account, the weighted retinal irradiance is 1.40 mW/cm 2 and the weighted retinal radiant exposure is 56.25 mJ/cm 2 . The peak weighted foveal irradiance is 1.61 mW/cm 2 . Our study concluded that the photobiological risk posed by iPhone 6 indirect ophthalmoscopy was at least 1 order of magnitude below the safety limits set by the ISO15004-2.2.

  7. Automated detection of retinal disease.

    Science.gov (United States)

    Helmchen, Lorens A; Lehmann, Harold P; Abràmoff, Michael D

    2014-11-01

    Nearly 4 in 10 Americans with diabetes currently fail to undergo recommended annual retinal exams, resulting in tens of thousands of cases of blindness that could have been prevented. Advances in automated retinal disease detection could greatly reduce the burden of labor-intensive dilated retinal examinations by ophthalmologists and optometrists and deliver diagnostic services at lower cost. As the current availability of ophthalmologists and optometrists is inadequate to screen all patients at risk every year, automated screening systems deployed in primary care settings and even in patients' homes could fill the current gap in supply. Expanding screens to all patients at risk by switching to automated detection systems would in turn yield significantly higher rates of detecting and treating diabetic retinopathy per dilated retinal examination. Fewer diabetic patients would develop complications such as blindness, while ophthalmologists could focus on more complex cases.

  8. Advances in Retinal Optical Imaging

    Directory of Open Access Journals (Sweden)

    Yanxiu Li

    2018-04-01

    Full Text Available Retinal imaging has undergone a revolution in the past 50 years to allow for better understanding of the eye in health and disease. Significant improvements have occurred both in hardware such as lasers and optics in addition to software image analysis. Optical imaging modalities include optical coherence tomography (OCT, OCT angiography (OCTA, photoacoustic microscopy (PAM, scanning laser ophthalmoscopy (SLO, adaptive optics (AO, fundus autofluorescence (FAF, and molecular imaging (MI. These imaging modalities have enabled improved visualization of retinal pathophysiology and have had a substantial impact on basic and translational medical research. These improvements in technology have translated into early disease detection, more accurate diagnosis, and improved management of numerous chorioretinal diseases. This article summarizes recent advances and applications of retinal optical imaging techniques, discusses current clinical challenges, and predicts future directions in retinal optical imaging.

  9. Retinal shows its true colours

    DEFF Research Database (Denmark)

    Coughlan, N. J.A.; Adamson, B. D.; Gamon, L.

    2015-01-01

    Retinal is one of Nature's most important and widespread chromophores, exhibiting remarkable versatility in its function and spectral response, depending on its protein environment. Reliable spectroscopic and photochemical data for the isolated retinal molecule are essential for calibrating theor...

  10. Paediatric retinal detachment: aetiology, characteristics and outcomes.

    Science.gov (United States)

    McElnea, Elizabeth; Stephenson, Kirk; Gilmore, Sarah; O'Keefe, Michael; Keegan, David

    2018-01-01

    To provide contemporary data on the aetiology, clinical features and outcomes of paediatric retinal detachment. A retrospective review of all those under 16y who underwent surgical repair for retinal detachment at a single centre between the years 2008 and 2015 inclusive was performed. In each case the cause of retinal detachment, the type of detachment, the presence or absence of macular involvement, the number and form of reparative surgeries undertaken, and the surgical outcome achieved was recorded. Twenty-eight eyes of 24 patients, 15 (62.5%) of whom were male and 9 (37.5%) of whom were female, their mean age being 11.6y and range 2-16y developed retinal detachment over the eight year period studied. Trauma featured in the development of retinal detachment in 14 (50.0%) cases. Retinal detachment was associated with other ocular and/or systemic conditions in 11 (39.3%) cases. A mean of 3.0 procedures with a range of 1-9 procedures per patient were undertaken in the management of retinal detachment. Complex vitrectomy combined with scleral buckling or complex vitrectomy alone were those most frequently performed. Mean postoperative visual acuity was 1.2 logMAR with range 0.0-3.0 logMAR. In 22 of 26 (84.6%) cases which underwent surgical repair the retina was attached at last follow-up. Aggressive management of paediatric retinal detachment including re-operation increases the likelihood of anatomical success. In cases where the retinal detachment can be repaired by an external approach alone there is a more favourable visual outcome.

  11. Establishment of an animal model of mice with radiation- injured soft tissue blood vessels

    International Nuclear Information System (INIS)

    Wang Daiyou; Yu Dahai; Wu Jiaxiao; Wei Shanliang; Wen Yuming

    2004-01-01

    Objective: The aim of this study was to establish an animal model of mice with radiation-injured soft tissue blood vessels. Methods: Forty male mice were irradiated with 30 Gy on the right leg. After the irradiation was finished each of the 40 male mice was tested with angiography, and its muscle tissues on the bilateral legs were examined with vessel staining assay and electron microscopy. Results: The results showed that the number of vessels on the right leg was less than that on the left leg, the microvessel density, average diameter and average sectional area of the right leg were all lower than those of the left, and the configuration and ultra-structure of vessels were also different between both sides of legs. Conclusion: In the study authors successfully established an animal model of mice with radiation-injured soft tissue blood vessels

  12. Retrobulbar optic neuritis and rhegmatogenous retinal detachment in a fourteen-year-old girl with retinitis pigmentosa sine pigmento.

    Science.gov (United States)

    Hatta, M; Hayasaka, S; Kato, T; Kadoi, C

    2000-01-01

    A 14-year-old girl complained of a sudden decrease in right visual acuity. The patient had night blindness, a mottled retina but no pigments, extinguished scotopic electroretinographic response, central scotoma in the right eye and rhegmatogenous retinal detachment. She had initially received laser photocoagulation around the retinal tear and then corticosteroid therapy, cryoretinopexy and segmental buckling. Her right visual acuity increased to 1.0. The association of retinitis pigmentosa sine pigmento, retrobulbar optic neuritis and rhegmatogenous retinal detachment, as demonstrated in our patient, may be uncommon. Copyright 2000 S. Karger AG, Basel

  13. Relationship between Retinal Vascular Caliber and Coronary Artery Disease in Patients with Non-Alcoholic Fatty Liver Disease (NAFLD

    Directory of Open Access Journals (Sweden)

    Marmor Alon

    2013-08-01

    Full Text Available Objective: To evaluate the relationship between retinal vascular caliber and cardiovascular disease in non-alcoholic fatty liver disease (NAFLD patients without diabetes and hypertension. Methods: Intention to treat study of individuals who underwent cardiac computed tomography (CT during a two year period. Coronary artery disease (CAD was defined as stenosis of >50% in at least one major coronary artery. Liver and spleen density were measured by abdominal (CT; intima-media thickness (IMT by Doppler ultrasound; retinal artery and vein diameter by colored-retinal angiography; and metabolic syndrome by ATP III guidelines. Serum biomarkers of insulin resistance, inflammation, and oxidant-antioxidant status were assessed. Results: Compared with 22 gender and age matched controls, the 29 NAFLD patients showed higher prevalence of coronary plaques (70% vs. 30%, p < 0.001, higher prevalence of coronary stenosis (30% vs. 15%, p < 0.001, lower retinal arteriole-to-venule ratio (AVR (0.66 ± 0.06 vs. 0.71 ± 0.02, p < 0.01, higher IMT (0.98 ± 0.3 vs. 0.83 ± 0.1, p < 0.04, higher carotid plaques (60% vs. 40%, p < 0.001, higher homeostasis model assessment of insulin resistance (HOMA (4.0 ± 3.4 vs. 2.0 ± 1.0, p < 0.005, and higher triglyceride levels (200 ± 80 vs. 150 ± 60, p < 0.005 than controls. Multivariate analysis showed fatty liver (OR 2.5; p < 0.01, IMT (OR 2.3 p < 0.001, and retinal AVR ratio (OR 1.5, p < 0.01 to be strongly associated with CAD independent of metabolic syndrome (OR 1.2, p < 0.05. Conclusions: Patients with smaller retinal AVR (<0.7 are likely to be at increased risk for CAD and carotid atherosclerosis in patients with NAFLD even without hypertension or diabetes.

  14. Genomic analysis of mouse retinal development.

    Directory of Open Access Journals (Sweden)

    Seth Blackshaw

    2004-09-01

    Full Text Available The vertebrate retina is comprised of seven major cell types that are generated in overlapping but well-defined intervals. To identify genes that might regulate retinal development, gene expression in the developing retina was profiled at multiple time points using serial analysis of gene expression (SAGE. The expression patterns of 1,051 genes that showed developmentally dynamic expression by SAGE were investigated using in situ hybridization. A molecular atlas of gene expression in the developing and mature retina was thereby constructed, along with a taxonomic classification of developmental gene expression patterns. Genes were identified that label both temporal and spatial subsets of mitotic progenitor cells. For each developing and mature major retinal cell type, genes selectively expressed in that cell type were identified. The gene expression profiles of retinal Müller glia and mitotic progenitor cells were found to be highly similar, suggesting that Müller glia might serve to produce multiple retinal cell types under the right conditions. In addition, multiple transcripts that were evolutionarily conserved that did not appear to encode open reading frames of more than 100 amino acids in length ("noncoding RNAs" were found to be dynamically and specifically expressed in developing and mature retinal cell types. Finally, many photoreceptor-enriched genes that mapped to chromosomal intervals containing retinal disease genes were identified. These data serve as a starting point for functional investigations of the roles of these genes in retinal development and physiology.

  15. Axial vessel widening in arborescent monocots.

    Science.gov (United States)

    Petit, Giai; DeClerck, Fabrice A J; Carrer, Marco; Anfodillo, Tommaso

    2014-02-01

    Dicotyledons have evolved a strategy to compensate for the increase in hydraulic resistance to water transport with height growth by widening xylem conduits downwards. In monocots, the accumulation of hydraulic resistance with height should be similar, but the absence of secondary growth represents a strong limitation for the maintenance of xylem hydraulic efficiency during ontogeny. The hydraulic architecture of monocots has been studied but it is unclear how monocots arrange their axial vascular structure during ontogeny to compensate for increases in height. We measured the vessel lumina and estimated the hydraulic diameter (Dh) at different heights along the stem of two arborescent monocots, Bactris gasipaes (Kunth) and Guadua angustifolia (Kunth). For the former, we also estimated the variation in Dh along the leaf rachis. Hydraulic diameter increased basally from the stem apex to the base with a scaling exponent (b) in the range of those reported for dicot trees (b = 0.22 in B. gasipaes; b = 0.31 and 0.23 in G. angustifolia). In B. gasipaes, vessels decrease in Dh from the stem's centre towards the periphery, an opposite pattern compared with dicot trees. Along the leaf rachis, a pattern of increasing Dh basally was also found (b = 0.13). The hydraulic design of the monocots studied revealed an axial pattern of xylem conduits similar to those evolved by dicots to compensate and minimize the negative effect of root-to-leaf length on hydrodynamic resistance to water flow.

  16. Comparison of the effectiveness of three retinal camera technologies for malarial retinopathy detection in Malawi

    Science.gov (United States)

    Soliz, Peter; Nemeth, Sheila C.; Barriga, E. Simon; Harding, Simon P.; Lewallen, Susan; Taylor, Terrie E.; MacCormick, Ian J.; Joshi, Vinayak S.

    2016-03-01

    The purpose of this study was to test the suitability of three available camera technologies (desktop, portable, and iphone based) for imaging comatose children who presented with clinical symptoms of malaria. Ultimately, the results of the project would form the basis for a design of a future camera to screen for malaria retinopathy (MR) in a resource challenged environment. The desktop, portable, and i-phone based cameras were represented by the Topcon, Pictor Plus, and Peek cameras, respectively. These cameras were tested on N=23 children presenting with symptoms of cerebral malaria (CM) at a malaria clinic, Queen Elizabeth Teaching Hospital in Malawi, Africa. Each patient was dilated for binocular indirect ophthalmoscopy (BIO) exam by an ophthalmologist followed by imaging with all three cameras. Each of the cases was graded according to an internationally established protocol and compared to the BIO as the clinical ground truth. The reader used three principal retinal lesions as markers for MR: hemorrhages, retinal whitening, and vessel discoloration. The study found that the mid-priced Pictor Plus hand-held camera performed considerably better than the lower price mobile phone-based camera, and slightly the higher priced table top camera. When comparing the readings of digital images against the clinical reference standard (BIO), the Pictor Plus camera had sensitivity and specificity for MR of 100% and 87%, respectively. This compares to a sensitivity and specificity of 87% and 75% for the i-phone based camera and 100% and 75% for the desktop camera. The drawback of all the cameras were their limited field of view which did not allow complete view of the periphery where vessel discoloration occurs most frequently. The consequence was that vessel discoloration was not addressed in this study. None of the cameras offered real-time image quality assessment to ensure high quality images to afford the best possible opportunity for reading by a remotely located

  17. Large-scale testing of in-vessel debris cooling through external flooding of the reactor pressure vessel in the CYBL facility

    International Nuclear Information System (INIS)

    Chu, T.Y.; Bentz, J.H.; Bergeron, K.D.; Slezak, S.E.; Simpson, R.B.

    1994-01-01

    The possibility of achieving in-vessel core retention by flooding the reactor cavity, or the ''flooded cavity'', is an accident management concept currently under consideration for advanced light water reactors (ALWR), as well as for existing light water reactors (LWR). The CYBL (CYlindrical BoiLing) facility is a facility specifically designed to perform large-scale confirmatory testing of the flooded cavity concept. CYBL has a tank-within-a-tank design; the inner 3.7 m diameter tank simulates the reactor vessel, and the outer tank simulates the reactor cavity. The energy deposition on the bottom head is simulated with an array of radiant heaters. The array can deliver a tailored heat flux distribution corresponding to that resulting from core melt convection. The present paper provides a detailed description of the capabilities of the facility, as well as results of recent experiments with heat flux in the range of interest to those required for in-vessel retention in typical ALWRs. The paper concludes with a discussion of other experiments for the flooded cavity applications

  18. Large-Scale testing of in-vessel debris cooling through external flooding of the reactor pressure vessel in the CYBL facility

    International Nuclear Information System (INIS)

    Chu, T.Y.; Bentz, J.H.; Bergeron, K.D.; Slezak, S.E.; Simpson, R.B.

    1994-01-01

    The possibility of achieving in-vessel core retention by flooding the reactor cavity, or the open-quotes flooded cavityclose quotes, is an accident management concept currently under consideration for advanced light water reactors (ALWR), as well as for existing light water reactors (LWR). The CYBL (CYlindrical BoiLing) facility is a facility specifically designed to perform large-scale confirmatory testing of the flooded cavity concept. CYBL has a tank-within-a-tank design; the inner 3.7 m diameter tank simulates the reactor vessel, and the outer tank simulates the reactor cavity. The energy deposition on the bottom head is simulated with an array of radiant heaters. The array can deliver a tailored heat flux distribution corresponding to that resulting from core melt convection. The present paper provides a detailed description of the capabilities of the facility, as well as results of recent experiments with heat flux in the range of interest to those required for in-vessel retention in typical ALWRs. The paper concludes with a discussion of other experiments for the flooded cavity applications

  19. Vitreo-retinal eye surgery robot : sustainable precision

    NARCIS (Netherlands)

    Meenink, H.C.M.

    2011-01-01

    Vitreo-retinal eye surgery encompasses the surgical procedures performed on the vitreous humor and the retina. A procedure typically consists of the removal of the vitreous humor, the peeling of a membrane and/or the repair of a retinal detachment. Vitreo-retinal surgery is performed minimal

  20. Astrocytes and Müller Cell Alterations During Retinal Degeneration in a Transgenic Rat Model of Retinitis Pigmentosa

    Science.gov (United States)

    Fernández-Sánchez, Laura; Lax, Pedro; Campello, Laura; Pinilla, Isabel; Cuenca, Nicolás

    2015-01-01

    Purpose: Retinitis pigmentosa includes a group of progressive retinal degenerative diseases that affect the structure and function of photoreceptors. Secondarily to the loss of photoreceptors, there is a reduction in retinal vascularization, which seems to influence the cellular degenerative process. Retinal macroglial cells, astrocytes, and Müller cells provide support for retinal neurons and are fundamental for maintaining normal retinal function. The aim of this study was to investigate the evolution of macroglial changes during retinal degeneration in P23H rats. Methods: Homozygous P23H line-3 rats aged from P18 to 18 months were used to study the evolution of the disease, and SD rats were used as controls. Immunolabeling with antibodies against GFAP, vimentin, and transducin were used to visualize macroglial cells and cone photoreceptors. Results: In P23H rats, increased GFAP labeling in Müller cells was observed as an early indicator of retinal gliosis. At 4 and 12 months of age, the apical processes of Müller cells in P23H rats clustered in firework-like structures, which were associated with ring-like shaped areas of cone degeneration in the outer nuclear layer. These structures were not observed at 16 months of age. The number of astrocytes was higher in P23H rats than in the SD matched controls at 4 and 12 months of age, supporting the idea of astrocyte proliferation. As the disease progressed, astrocytes exhibited a deteriorated morphology and marked hypertrophy. The increase in the complexity of the astrocytic processes correlated with greater connexin 43 expression and higher density of connexin 43 immunoreactive puncta within the ganglion cell layer (GCL) of P23H vs. SD rat retinas. Conclusions: In the P23H rat model of retinitis pigmentosa, the loss of photoreceptors triggers major changes in the number and morphology of glial cells affecting the inner retina. PMID:26733810