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Sample records for intraocular pressure elevation

  1. Blood pressure modifies retinal susceptibility to intraocular pressure elevation.

    Directory of Open Access Journals (Sweden)

    Zheng He

    Full Text Available Primary open angle glaucoma affects more than 67 million people. Elevated intraocular pressure (IOP is a risk factor for glaucoma and may reduce nutrient availability by decreasing ocular perfusion pressure (OPP. An interaction between arterial blood pressure and IOP determines OPP; but the exact contribution that these factors have for retinal function is not fully understood. Here we sought to determine how acute modifications of arterial pressure will affect the susceptibility of neuronal function and blood flow to IOP challenge. Anaesthetized (ketamine:xylazine Long-Evan rats with low (∼60 mmHg, sodium nitroprusside infusion, moderate (∼100 mmHg, saline, or high levels (∼160 mmHg, angiotensin II of mean arterial pressure (MAP, n = 5-10 per group were subjected to IOP challenge (10-120 mmHg, 5 mmHg steps every 3 minutes. Electroretinograms were measured at each IOP step to assess bipolar cell (b-wave and inner retinal function (scotopic threshold response or STR. Ocular blood flow was measured using laser-Doppler flowmetry in groups with similar MAP level and the same IOP challenge protocol. Both b-wave and STR amplitudes decreased with IOP elevation. Retinal function was less susceptible to IOP challenge when MAP was high, whereas the converse was true for low MAP. Consistent with the effects on retinal function, higher IOP was needed to attenuated ocular blood flow in animals with higher MAP. The susceptibility of retinal function to IOP challenge can be ameliorated by acute high BP, and exacerbated by low BP. This is partially mediated by modifications in ocular blood flow.

  2. Systems genetics identifies a role for Cacna2d1 regulation in elevated intraocular pressure and glaucoma susceptibility

    OpenAIRE

    Chintalapudi, Sumana R.; Maria, Doaa; Di Wang, Xiang; Bailey, Jessica N. Cooke; Hysi, Pirro G.; Wiggs, Janey L.; Williams, Robert W.; Jablonski, Monica M.

    2017-01-01

    textabstractGlaucoma is a multi-factorial blinding disease in which genetic factors play an important role. Elevated intraocular pressure is a highly heritable risk factor for primary open angle glaucoma and currently the only target for glaucoma therapy. Our study helps to better understand underlying genetic and molecular mechanisms that regulate intraocular pressure, and identifies a new candidate gene, Cacna2d1, that modulates intraocular pressure and a promising therapeutic, pregabalin, ...

  3. Suppressive effect of astaxanthin on retinal injury induced by elevated intraocular pressure.

    Science.gov (United States)

    Cort, Aysegul; Ozturk, Nihal; Akpinar, Deniz; Unal, Mustafa; Yucel, Gultekin; Ciftcioglu, Akif; Yargicoglu, Piraye; Aslan, Mutay

    2010-10-01

    The aim of this study was to clarify the possible protective effect of astaxanthin (ASX) on the retina in rats with elevated intraocular pressure (EIOP). Rats were randomly divided into two groups which received olive oil or 5mg/kg/day ASX for a period of 8 weeks. Elevated intraocular pressure was induced by unilaterally cauterizing three episcleral vessels and the unoperated eye served as control. At the end of the experimental period, neuroprotective effect of ASX was determined via electrophysiological measurements of visual evoked potentials (VEP) and rats were subsequently sacrificed to obtain enucleated globes which were divided into four groups including control, ASX treated, EIOP, EIOP+ASX treated. Retinoprotective properties of ASX were determined by evaluating retinal apoptosis, protein carbonyl levels and nitric oxide synthase-2 (NOS-2) expression. Latencies of all VEP components were significantly prolonged in EIOP and returned to control levels following ASX administration. When compared to controls, EIOP significantly increased retinal protein oxidation which returned to baseline levels in ASX treated EIOP group. NOS-2 expression determined by Western blot analysis and immunohistochemical staining was significantly greater in rats with EIOP compared to ASX and control groups. Retinal TUNEL staining showed apoptosis in all EIOP groups; however ASX treatment significantly decreased the percent of apoptotic cells when compared to non treated ocular hypertensive controls. The presented data confirm the role of oxidative injury in EIOP and highlight the protective effect of ASX in ocular hypertension. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  4. Evaulation of Incidence and Risk Factors for Intraocular Pressure Elevation After Intravitreal Triamcinolone Acetonide Injection

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    Didar Uçar

    2015-05-01

    Full Text Available Objectives: To investigate the effect of intravitreal triamcinolone acetonide (IVTA used for the macular edema on intraocular pressure (IOP and to determine the risk factors for IOP elevation. Materials and Methods: This retrospective study included 93 eyes of 85 patients who had 4 mg intravitreal triamcinolone injection. Of the 85 patients, 56 (65.8% had diabetic macular edema, 22 (25.8% had branch retinal, and 7 (8.2% had central retinal vein occlusion. IOP changes after injection as well as the relation between IOP elevation and age, sex, lens status, etiology of macular edema, baseline IOP were evaluated. Results: Fourty-six male and 39 female patients with mean age 61.58±9.5 years were evaluated. IOP was recorded to be >24 mmHg in 30 eyes (32.2% at follow-up visit after an average of 7.5 weeks. Normalization of IOP with medication was achieved in all IOP elevated eyes. Fifteen of 29 eyes (51.7% with vein occlusion and 15 of 64 eyes (23.3% with diabetic macula edema had IOP elevation (p=0.01. Twenty-six of 73 phakic (35.6% and 4 of 20 pseudophakic eyes (20% had IOP >24 mmHg (p=0.16. There was no association between IOP elevation and sex (p=0.33. Baseline IOP was 16.47±2.8 mmHg in eyes which had elevated IOP and 14.78±2.4 mmHg in the remaining. There was significant relation between IOP elevation and baseline IOP level (p=0.01. Conclusion: Elevated IOP is common side effect after IVTA, but normalization is usually achieved by topical medication. Patients with baseline IOP ≥15 mmHg and vein occlusion have higher risk for IOP elevation. (Turk J Ophthalmol 2015; 45: 86-91

  5. Systems genetics identifies a role for Cacna2d1 regulation in elevated intraocular pressure and glaucoma susceptibility

    NARCIS (Netherlands)

    Chintalapudi, S.R. (Sumana R.); Maria, D. (Doaa); Di Wang, X. (Xiang); Bailey, J.N.C. (Jessica N. Cooke); Allingham, R. (Rand); M.H. Brilliant (Murray H.); D.L. Budenz (Donald L.); J. Fingert (John); D. Gaasterland (Douglas); T. Gaasterland (Terry); J.L. Haines (Jonathan); Hark, L. (Lisa); M.A. Hauser (Michael); R.P. Igo Jr. (Robert); Hee Kang, J. (Jae); P. Kraft (Peter); R.K. Lee (Richard K.); P.A. Lichter (Paul A.); Liu, Y. (Yutao); Moroi, S. (Syoko); L.R. Pasquale (Louis); M.A. Pericak-Vance (Margaret); A. Realini (Anthony); Rhee, D. (Doug); Richards, J.R. (Julia R.); Ritch, R. (Robert); J.S. Schuman (Joel S.); W.K. Scott (William); K. Singh (Kuldev); A.J. Sit (Arthur J.); D. Vollrath (Douglas); G. Wollstein (Gadi); D.J. Zack (Donald); T. Aung (Tin); Bonnemaijer, P. (Peter); Cheng, C.-Y. (Cheng-Yu); J.E. Craig (Jamie); C.M. van Duijn (Cornelia); P. Gharahkhani (Puya); Iglesias Gonzalez, A. (Adriana); Hammond, C.J. (Christopher J.); Hewitt, A. (Alex); Hoehn, R. (Rene); Jonansson, F. (Fridbert); A.P. Khawaja (Anthony); Chuen Khor, C. (Chiea); C.C.W. Klaver (Caroline); A.J. Lotery (Andrew); D.A. Mackey (David); MacGregor, S. (Stuart); Pang, C. (Calvin); F. Pasutto (Francesca); J-A. Zwart (John-Anker); G. Thorleifsson (Gudmar); Thorsteinsdottir, U. (Unnar); V. Vitart (Veronique); E.N. Vithana (Eranga); T.L. Young (Terri L.); T. Zeller (Tanja); P.G. Hysi (Pirro); J.L. Wiggs (Janey L.); R.W. Williams (Robert W.); Jablonski, M.M. (Monica M.)

    2017-01-01

    textabstractGlaucoma is a multi-factorial blinding disease in which genetic factors play an important role. Elevated intraocular pressure is a highly heritable risk factor for primary open angle glaucoma and currently the only target for glaucoma therapy. Our study helps to better understand

  6. Pigmented and albino rats differ in their responses to moderate, acute and reversible intraocular pressure elevation.

    Science.gov (United States)

    Gurdita, Akshay; Tan, Bingyao; Joos, Karen M; Bizheva, Kostadinka; Choh, Vivian

    2017-06-01

    To compare the electrophysiological and morphological responses to acute, moderately elevated intraocular pressure (IOP) in Sprague-Dawley (SD), Long-Evans (LE) and Brown Norway (BN) rat eyes. Eleven-week-old SD (n = 5), LE (n = 5) and BN (n = 5) rats were used. Scotopic threshold responses (STRs), Maxwellian flash electroretinograms (ERGs) or ultrahigh-resolution optical coherence tomography (UHR-OCT) images of the rat retinas were collected from both eyes before, during and after IOP elevation of one eye. IOP was raised to ~35 mmHg for 1 h using a vascular loop, while the other eye served as a control. STRs, ERGs and UHR-OCT images were acquired on 3 days separated by 1 day of no experimental manipulation. There were no significant differences between species in baseline electroretinography. However, during IOP elevation, peak positive STR amplitudes in LE (mean ± standard deviation 259 ± 124 µV) and BN (228 ± 96 µV) rats were about fourfold higher than those in SD rats (56 ± 46 µV) rats (p = 0.0002 for both). Similarly, during elevated IOP, ERG b-wave amplitudes were twofold higher in LE and BN rats compared to those of SD rats (947 ± 129 µV and 892 ± 184 µV, vs 427 ± 138 µV; p = 0.0002 for both). UHR-OCT images showed backward bowing in all groups during IOP elevation, with a return to typical form about 30 min after IOP elevation. Differences in the loop-induced responses between the strains are likely due to different inherent retinal morphology and physiology.

  7. Systems genetics identifies a role for Cacna2d1 regulation in elevated intraocular pressure and glaucoma susceptibility.

    Science.gov (United States)

    Chintalapudi, Sumana R; Maria, Doaa; Di Wang, Xiang; Bailey, Jessica N Cooke; Hysi, Pirro G; Wiggs, Janey L; Williams, Robert W; Jablonski, Monica M

    2017-11-24

    Glaucoma is a multi-factorial blinding disease in which genetic factors play an important role. Elevated intraocular pressure is a highly heritable risk factor for primary open angle glaucoma and currently the only target for glaucoma therapy. Our study helps to better understand underlying genetic and molecular mechanisms that regulate intraocular pressure, and identifies a new candidate gene, Cacna2d1, that modulates intraocular pressure and a promising therapeutic, pregabalin, which binds to CACNA2D1 protein and lowers intraocular pressure significantly. Because our study utilizes a genetically diverse population of mice with known sequence variants, we are able to determine that the intraocular pressure-lowering effect of pregabalin is dependent on the Cacna2d1 haplotype. Using human genome-wide association study (GWAS) data, evidence for association of a CACNA2D1 single-nucleotide polymorphism and primary open angle glaucoma is found. Importantly, these results demonstrate that our systems genetics approach represents an efficient method to identify genetic variation that can guide the selection of therapeutic targets.

  8. Apraclonidine versus brinzolamide-timolol combination to prevent intraocular pressure elevation after laser capsulotomy

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    Erkan Çelik

    2016-01-01

    Full Text Available AIM: To compare the efficacy of fixed combination of brinzolamide 1% and timolol 0.5%(FCBTwith apraclonidine 0.5%(APRAin preventing intraocular pressure(IOPelevations after neodymium: yttrium-aluminum-garnet(Nd:YAGlaser posterior capsulotomy.METHODS: This prospective randomized clinical study included 90 eyes of 90 consecutive patients who had Nd:YAG laser posterior capsulotomy for posterior capsule opacification(PCO. Patients were randomized to receive APRA(n=45or FCBT(n=45at 1h before laser surgery. A masked observer measured IOP by Goldmann applanation tonometry before the procedure and at 1, 2, 3, 24h and 7d after laser treatment. IOP outcome measures were grouped into the following categories: post laser IOP elevation of 5 to RESULTS:The mean IOP before surgery on the day of the procedure was 14.1±2.1 mm Hg in the APRA group and 13.2±2.1 mm Hg in the FCBT group. There was no statistically significant difference between the APRA and the FCBT groups of baseline IOPs measured(P=0.066. During the follow-up time, the mean IOP was lower in FCBT group, but this was not statistically significant. Six patients(13.3%in APRA group and 4(8.9%in FCBT group had IOP elevations of 5 to P=0.243. IOP elevations of 10 mm Hg or more occurred in 3 eyes(6.7%in the APRA group and 1 eyes(2.2%in the FCBT group; this was not statistically significant(P=0.542. CONCLUSION:Both of APRA and FCBT are effective for prevention and APRA is enough for most of routine cases. FCBT may be an option for the eyes those need more IOP reduction such as pre-existing glaucoma patients who are at higher risk for postoperative IOP elevations.

  9. Genetic context determines susceptibility to intraocular pressure elevation in a mouse pigmentary glaucoma

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    Cosma Ioan M

    2006-07-01

    Full Text Available Abstract Background DBA/2J (D2 mice develop an age-related form of glaucoma. Their eyes progressively develop iris pigment dispersion and iris atrophy followed by increased intraocular pressure (IOP and glaucomatous optic nerve damage. Mutant alleles of the Gpnmb and Tyrp1 genes are necessary for the iris disease, but it is unknown whether alleles of other D2 gene(s are necessary for the distinct later stages of disease. We initiated a study of congenic strains to further define the genetic requirements and disease mechanisms of the D2 glaucoma. Results To further understand D2 glaucoma, we created congenic strains of mice on the C57BL/6J (B6 genetic background. B6 double-congenic mice carrying D2-derived Gpnmb and Tyrp1 mutations develop a D2-like iris disease. B6 single-congenics with only the Gpnmb and Tyrp1 mutations develop milder forms of iris disease. Genetic epistasis experiments introducing a B6 tyrosinase mutation into the congenic strains demonstrated that both the single and double-congenic iris diseases are rescued by interruption of melanin synthesis. Importantly, our experiments analyzing mice at ages up to 27 months indicate that the B6 double-congenic mice are much less prone to IOP elevation and glaucoma than are D2 mice. Conclusion As demonstrated here, the Gpnmb and Tyrp1 iris phenotypes are both individually dependent on tyrosinase function. These results support involvement of abnormal melanosomal events in the diseases caused by each gene. In the context of the inbred D2 mouse strain, the glaucoma phenotype is clearly influenced by more genes than just Gpnmb and Tyrp1. Despite the outward similarity of pigment-dispersing iris disease between D2 and the B6 double-congenic mice, the congenic mice are much less susceptible to developing high IOP and glaucoma. These new congenic strains provide a valuable new resource for further studying the genetic and mechanistic complexity of this form of glaucoma.

  10. Intraocular pressure estimation using proper orthogonal decomposition

    CSIR Research Space (South Africa)

    Botha, N

    2012-07-01

    Full Text Available Glaucoma is the second leading cause of irreversible blindness. The primary indicator for glaucoma is an elevated intraocular pressure, which is estimated by means of contact or non-contact tonometry. However, these techniques do not accurately...

  11. Measurement of amino acid levels in the vitreous humor of rats after chronic intraocular pressure elevation or optic nerve transection.

    Science.gov (United States)

    Levkovitch-Verbin, Hana; Martin, Keith R G; Quigley, Harry A; Baumrind, Lisa A; Pease, Mary Ellen; Valenta, Danielle

    2002-10-01

    To investigate whether the levels of free amino acids and protein in the vitreous of rat eyes are altered with chronic intraocular pressure (IOP) elevation or after optic nerve transection. The concentrations of 20 amino acids in the vitreous humor were measured by high-performance liquid chromatography in both eyes of 41 rats with unilateral IOP elevation induced by translimbal photocoagulation. Eyes were studied 1 day and 1, 2, 4, and 9 weeks after initial IOP elevation. The same amino acids were measured in 41 rats 1 day and 2, 4, and 9 weeks after unilateral transection of the orbital optic nerve. The intravitreal protein level was assayed in additional 22 rats with IOP elevation and 12 rats after nerve transection. Two masked observers evaluated the amount of optic nerve damage with a semiquantitative, light-microscopic technique. In rats with experimental glaucoma, amino acid concentrations were unchanged 1 day after treatment. At 1 week, 4 of 20 amino acids (aspartate, proline, alanine, and lysine) were higher than in control eyes ( 0.05). Vitreous protein level was significantly higher in glaucomatous eyes than their paired controls at 1 day ( 0.01).

  12. Effect of acute intraocular pressure elevation on the minimum rim width in normal, ocular hypertensive and glaucoma eyes.

    Science.gov (United States)

    Sharma, Sourabh; Tun, Tin A; Baskaran, Mani; Atalay, Eray; Thakku, Sri Gowtham; Liang, Zhang; Milea, Dan; Strouthidis, Nicholas G; Aung, Tin; Girard, Michael Ja

    2018-01-01

    To estimate and compare changes in the Bruch's membrane opening-minimum rim width (BMO-MRW) and area in normal, ocular hypertensive and glaucoma eyes following acute elevations in intraocular pressure (IOP). The optic nerve heads (ONHs) of 104 subjects (31 normals, 20 ocular hypertension (OHT) and 53 with primary glaucoma) were imaged using Spectral-domain optical coherence tomography (OCT; Spectralis, Heidelberg Engineering, Germany). IOP was raised twice by applying a force (0.64 n then 0.9 n) to the anterior sclera using an ophthalmo-dynamometer. After each IOP increment, IOP was held constant, measured with a Tonopen (AVIA applanation tonometer, Reichert, Depew, New York, USA), and ONH was rescanned with OCT. In each OCT volume, BMO-MRW and area were calculated and at each IOP increment. The baseline MRW was significantly smaller in glaucoma subjects (174.3±54.3 µm) compared with normal (287.4±42.2 µm, pglaucoma subjects was significantly thinner at the first and second IOP elevations than that at baseline (both p0.05). Acute IOP elevation leads to compression of the nerve fibre layers of neuroretinal rim in glaucoma subjects only without changing ONH size. This suggests that the neural and connective tissues at ONH level in glaucoma subjects are more susceptible to acute IOP episodes than OHT or normal controls. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  13. Spectral domain optical coherence tomography cross-sectional image of optic nerve head during intraocular pressure elevation

    Directory of Open Access Journals (Sweden)

    Ji Young Lee

    2014-12-01

    Full Text Available AIM: To analyze changes of the optic nerve head (ONH and peripapillary region during intraocular pressure (IOP elevation in patients using spectral domain optical coherence tomography (SD-OCT.METHODS: Both an optic disc 200×200 cube scan and a high-definition 5-line raster scan were obtained from open angle glaucoma patients presented with monocular elevation of IOP (≥30 mm Hg using SD-OCT. Additional baseline characteristics included age, gender, diagnosis, best-corrected visual acuity, refractive error, findings of slit lamp biomicroscopy, findings of dilated stereoscopic examination of the ONH and fundus, IOP, pachymetry findings, and the results of visual field.RESULTS: The 24 patients were selected and divided into two groups:group 1 patients had no history of IOP elevation or glaucoma (n=14, and group 2 patients did have history of IOP elevation or glaucoma (n=10. In each patient, the study eye with elevated IOP was classified into group H (high, and the fellow eye was classified into group L (low. The mean deviation (MD differed significantly between groups H and L when all eyes were considered (P=0.047 and in group 2 (P=0.042, not in group 1 (P=0.893. Retinal nerve fiber layer (RNFL average thickness (P=0.050, rim area (P=0.015, vertical cup/disc ratio (P=0.011, cup volume (P=0.028, inferior quadrant RNFL thickness (P=0.017, and clock-hour (1, 5, and 6 RNFL thicknesses (P=0.050, 0.012, and 0.018, respectively, cup depth (P=0.008, central prelaminar layer thickness (P=0.023, mid-inferior prelaminar layer thickness (P=0.023, and nasal retinal slope (P=0.034 were significantly different between the eyes with groups H and L.CONCLUSION:RNFL average thickness, rim area, vertical cup/disc ratio, cup volume, inferior quadrant RNFL thickness, and clock-hour (1, 5, and 6 RNFL thicknesses significantly changed during acute IOP elevation.

  14. The dark phase intraocular pressure elevation and retinal ganglion cell degeneration in a rat model of experimental glaucoma☆

    Science.gov (United States)

    Kwong, Jacky M.K.; Vo, Nancy; Quan, Ann; Nam, Michael; Kyung, Haksu; Yu, Fei; Piri, Natik; Caprioli, Joseph

    2013-01-01

    Intraocular pressure (IOP) elevation is considered as a major risk factor causing the progression of vision deterioration in glaucoma. Although it is known that the IOP level changes widely throughout the day and night, how the dark or light phase IOP elevation contributes to retinal ganglion cell (RGC) degeneration is still largely unclear. To examine the profile of IOP, modified laser photocoagulation was applied to the trabecular meshwork of Brown Norway rats and both light and dark phase IOPs were monitored approximately 1–2 times a week. The relationship between IOP elevation and RGC degeneration was investigated while RGC body loss was analyzed with Rbpms immunolabeling on retinal wholemount and axonal injury in the optic nerve was semi-quantified. The baseline awake dark and light IOPs were 30.4 ± 2.7 and 20.2 ± 2.1 mmHg respectively. The average dark IOP was increased to 38.2 ± 3.2 mmHg for five weeks after the laser treatment on 270° trabecular meshwork. However, there was no significant loss of RGC body and axonal injury. After laser treatment on 330° trabecular meshwork, the dark and light IOPs were significantly increased to 43.8 ± 4.6 and 23 ± 3.7 mmHg respectively for 5 weeks. The cumulative dark and light IOP elevations were 277 ± 86 and 113 ± 50 mmHg days respectively while the cumulative total (light and dark) IOP elevation was 213 ± 114 mmHg days. After 5 weeks, regional RGC body loss of 29.5 ± 15.5% and moderate axonal injury were observed. Axonal injury and loss of RGC body had a high correlation with the cumulative total IOP elevation (R2 = 0.60 and 0.65 respectively). There was an association between the cumulative dark IOP elevation and RGC body loss (R2 = 0.37) and axonal injury (R2 = 0.51) whereas the associations between neuronal damages and the cumulative light IOP elevation were weak (for RGC body loss, R2 = 0.01; for axonal injury, R2 = 0.26). Simple linear regression model analysis showed statistical significance for the

  15. Intraocular pressure reduction and regulation system

    Science.gov (United States)

    Baehr, E. F.; Burnett, J. E.; Felder, S. F.; Mcgannon, W. J.

    1979-01-01

    An intraocular pressure reduction and regulation system is described and data are presented covering performance in: (1) reducing intraocular pressure to a preselected value, (2) maintaining a set minimum intraocular pressure, and (3) reducing the dynamic increases in intraocular pressure resulting from external loads applied to the eye.

  16. The Effect of Acutely Elevated Intraocular Pressure on the Functional and Blood Flow Responses of the Rat Retina to Flicker Stimulation.

    Science.gov (United States)

    Tan, Bingyao; MacLellan, Benjamin; Mason, Erik; Bizheva, Kostadinka K

    2017-10-01

    To evaluate the effect of acutely elevated intraocular pressure (IOP) on the functional and blood flow responses of the rat retina to flicker stimulation. Brown Norway (n = 15) rats were dark-adapted before ketamine/xylazine anesthesia. IOP was raised acutely in one eye to ∼45 mm Hg with a vascular loop. In 11 rats, white light flicker stimulus (10 Hz, 2 seconds duration, 0.80 log scotopic cd·s/m2) was applied before and during IOP elevation, and 10 minutes after loop removal. Changes in the total retinal blood flow (TRBF) and retinal function induced by the visual stimulus were measured simultaneously with a combined optical coherence tomography (OCT) + electroretinography (ERG) system. Systemic blood pressure was measured in the remaining four rats frequently from 10 to 90 minutes post anesthesia injection. The systemic blood pressure remained at 99 ± 4 mm Hg throughout the measurements (n = 4). Under normal IOP, the TRBF was 5.6 ± 1.9 μL/min, and the average retinal blood vessel size (BVS) in the vicinity of the optic nerve head (ONH) was 44.1 ± 4.5 μm. During IOP elevation, the TRBF was significantly lower (3.8 ± 1.2 μL/min, P flicker-induced TRBF change measured under normal IOP (6.0 ± 3.3%) was reduced significantly to 0.1 ± 0.3% (P flicker stimulation.

  17. [The affect of Erigeron Breviscapus (Vant.) Hand-Mazz on axoplasmic transport of optic nerve in rats with experimentally elevated intraocular pressure].

    Science.gov (United States)

    Zhu, Y; Jiang, Y; Liu, Z; Luo, X; Wu, Z

    2000-07-01

    To investigate whether Erigeron Breviscapus (Vant.) Hand-Mazz (EBHM) can improve the optic nerve axoplasmic transport in rats with experimentally elevated intraocular pressure (IOP). Thirty healthy SD rats were used for the study, acute elevated IOP model in the right eye was built, then they were divided into three groups randomly: Group A (0 day group) included six rats for retinal ganglion cell (RGC) counting via left superior colliculus retrograde horse radish perokidase labeling; Group B, twelve rats divided into EBHM treatment group and control group (6 rats in each subgroup) for RGC counting via left superior colliculus retrograde labeling after twenty days, and Group C included twelve rats submitted the same treatment and procedure as group B after 40 days. After 0 day of acute elevated IOP, no labeled RGCs were observed. After twenty days of acute elevated IOP, in the control and EBHM subgroups the density of labeled RGCs were (423 +/- 220)/mm(2) and (749 +/- 294)/mm(2) respectively, the difference between two subgroups showed statistical significance (P < 0.01). After 40 days of acute elevated IOP, the density of RGCs in the control and EBHM subgroups in group C were (610 +/- 315)/mm(2) and (1,048 +/- 393)/mm(2) respectively, the difference between the two subgroups being statistically significant (P < 0.01). After 20 days and 40 days of acute elevation of IOP, the density of RGCs is obviously higher in EBHM group than that in the control group. It is revealed that EBHM can improve the optic nerve axoplasmic transportation blocked by acute elevation of IOP in rats.

  18. Roles of PI3K and JAK pathways in viability of retinal ganglion cells after acute elevation of intraocular pressure in rats with different autoimmune backgrounds

    Directory of Open Access Journals (Sweden)

    Wang Ningli

    2008-08-01

    Full Text Available Abstract Background We recently showed that whereas inhibition of PI3K/akt or JAK/STAT pathway promoted retinal ganglion cell (RGC survival after optic nerve (ON injury in Fischer 344 (F344 rats, the same inhibition resulted in aggravated RGC loss after acute intraocular pressure (IOP elevation in Sprague Dawley (SPD rats. In addition, the responses of macrophages to ON injury and acute IOP elevation were different between F344 and Lewis rats, i.e., different autoimmune profiles. Using an acute IOP elevation paradigm in this study, we investigated 1 whether autoimmune background influences PI3K/akt and JAK/STAT functions by examining the effect of PI3K/akt and JAK/STAT pathway inhibition on RGC survival in F344 and Lewis rats, and 2 whether differential actions of macrophages occur in PI3K/akt and JAK/STAT pathways-dependent modulation of RGC survival. IOP elevation was performed at 110 mmHg for 2 hours. PI3K/akt and JAK/STAT pathway inhibitors were applied intravitreally to block their respective pathway signaling transduction. Because macrophage invasion was seen in the eye after the pathway inhibition, to examine the role of these pathways independent of macrophages, macrophages in the retina were removed by intravitreal application of clodronate liposomes. Viable RGCs were retrogradely labelled by FluoroGold 40 hours before animal sacrifice. Results Similar to what was previously observed, significantly more RGCs were lost in Lewis than F344 rats 3 weeks after acute IOP elevation. As in SPD rats, inhibition of the PI3K/akt or JAK/STAT pathway increased the loss of RGCs in both F344 and Lewis rats. Removal of macrophages in the eye by clodronate liposomes reduced RGC loss due to pathway inhibition in both strains. Conclusion This study demonstrates that following acute IOP elevation 1 PI3K/akt and JAK/STAT pathways mediate RGC survival in both F344 and Lewis rats, 2 autoimmune responses do not influence the functions of these two pathways

  19. Ultrasonic measurement of scleral cross-sectional strains during elevations of intraocular pressure: method validation and initial results in posterior porcine sclera.

    Science.gov (United States)

    Tang, Junhua; Liu, Jun

    2012-09-01

    Scleral biomechanical properties may be important in the pathogenesis and progression of glaucoma. The goal of this study is to develop and validate an ultrasound method for measuring cross-sectional distributive strains in the sclera during elevations of intraocular pressure (IOP). Porcine globes (n = 5) were tested within 24 hs postmortem. The posterior scleral shells were dissected and mounted onto a custom-built pressurization chamber. A high-frequency (55-MHz) ultrasound system (Vevo660, VisualSonics Inc., Toronto) was employed to acquire the radio frequency data during scans of the posterior pole along both circumferential and meridian directions. The IOP was gradually increased from 5 to 45 mmHg. The displacement fields were obtained from correlation-based ultrasound speckle tracking. A least-square strain estimator was used to calculate the strains in both axial and lateral directions. Experimental validation was performed by comparing tissue displacements calculated from ultrasound speckle tracking with those induced by an actuator. Theoretical analysis and simulation experiments were performed to optimize the ultrasound speckle tracking method and evaluate the accuracy and signal-to-noise ratio (SNR) in strain estimation. Porcine sclera exhibited significantly larger axial strains (e.g., -5.1 ± 1.5% at 45 mmHg, meridian direction) than lateral strains (e.g., 2.2 ± 0.7% at 45 mmHg, meridian direction) during IOP elevations (P's estimation SNR on the strain level, as well as signal processing parameters such as kernel size. Simulation results showed that ultrasound speckle tracking had a high accuracy for estimating strains of 1-5% and a high SNR for strains of 0.5-5%. A new experimental method based on ultrasound speckle tracking has been developed for obtaining cross-sectional strain maps of the posterior sclera. This method provides a useful tool to examine distributive strains through the thickness of the sclera during elevations of IOP.

  20. Associations with intraocular pressure across Europe

    DEFF Research Database (Denmark)

    Khawaja, Anthony P; Springelkamp, Henriët; Creuzot-Garcher, Catherine

    2016-01-01

    Raised intraocular pressure (IOP) is the most important risk factor for developing glaucoma, the second commonest cause of blindness globally. Understanding associations with IOP and variations in IOP between countries may teach us about mechanisms underlying glaucoma. We examined cross-sectional...

  1. Intraocular Pressure in Pregnant and Non-Pregnant Nigerian Women

    African Journals Online (AJOL)

    Erah

    A number of hormones are known to affect intraocular pressure. Of these, the female sex hormones are the predominant ones to cause variations in intraocular pressure. The aim of this study was to determine if variation in sex hormones in pregnancy affects intraocular pressure. This study was a longitudinal one.

  2. Increased Intraocular Pressure after Extensive Conjunctival Removal: A Case Report

    OpenAIRE

    Lee, Young Rok; Na, Jung Hwa; Kim, Jae Yong; Sung, Kyung Rim

    2013-01-01

    A 50-year-old woman, who had undergone extensive removal of conjunctiva on the right eye for cosmetic purposes at a local clinic 8 months prior to presentation, was referred for uncontrolled intraocular pressure (IOP) elevation (up to 38 mmHg) despite maximal medical treatment. The superior and inferior conjunctival and episcleral vessels were severely engorged and the nasal and temporal bulbar conjunctival areas were covered with an avascular epithelium. Gonioscopic examination revealed an o...

  3. The interaction between intracranial pressure, intraocular pressure and lamina cribrosal compression in glaucoma.

    Science.gov (United States)

    McMonnies, Charles W

    2016-05-01

    This review examines some of the biomechanical consequences associated with the opposing intraocular and intracranial forces. These forces compress the lamina cribrosa and are a potential source of glaucomatous pathology. A difference between them creates a displacement force on the lamina cribrosa. Increasing intraocular pressure and/or decreasing intracranial pressure will increase the trans-lamina cribrosa pressure difference and the risk of its posterior displacement, canal expansion and the formation of pathological cupping. Both intraocular pressure and intracranial pressure can be elevated during a Valsalva manoeuvre with associated increases in both anterior and posterior lamina cribrosa loading as well as its compression. Any resulting thinning of or damage to the lamina cribrosa and/or retinal ganglion cell axons and/or astrocyte and glial cells attached to the matrix of the lamina cribrosa and/or reduction in blood flow to the lamina cribrosa may contribute to glaucomatous neuropathy. Thinning of the lamina cribrosa reduces its stiffness and increases the risk of its posterior displacement. Optic nerve head posterior displacement warrants medical or surgical lowering of intraocular pressure; however, compared to intraocular pressure, the trans-lamina cribrosa pressure difference may be more important in pressure-related pathology of the optic nerve head region. Similarly important could be increased compression loading of the lamina cribrosa. Reducing participation in activities which elevate intraocular and intracranial pressure will decrease lamina cribrosa compression exposure and may contribute to glaucoma management and may have prognostic significance for glaucoma suspects. © 2016 The Authors. Clinical and Experimental Optometry © 2016 Optometry Australia.

  4. [Changes in intraocular pressure depending on posture].

    Science.gov (United States)

    Barac, Ramona; Pop, Monica; Tătaru, C; Gheorghe, A; Bădescu, Silvia; Stanciu, Maria; Burcea, M

    2014-01-01

    Glaucoma is an important eye disease that, left untreated, causes irreversible blindness by affecting optic nerve threads. Decreasing intraocular pressure and maintaining it at a low level throughout the day is one of the objectives of antiglaucoma therapy. This is a prospective study conducted on a sample of 80 patients who presented at "Emergency Eye Hospital" Bucharest between 1st of December 2013 30th of July 2014. Patients were divided into two groups: 40 patients with glaucoma and 40 patients without glaucoma (control group). THE OBJECTIVE OF THE STUDY: To determine changes in intraocular pressure that may occur depending on body posture and the correlations between changes in intraocular pressure and glaucoma, obesity, hypertension. These IOP changes may be important in the progression of glaucoma regarding that one third of our time is spent on supine position during night. RESULTS AND CONCLUZIONS: IOP varies from sitting down to supine position. IOP increases in supine in most patients (with or without glaucoma) with an average of 1.25 mmHg. The increase among patients with glaucoma is higher (1.67 mmHg) compared to those without glaucoma (0.82 mmHg). In patients with hypertension and glaucoma, IOP increased with 2.62 mmHg. In patients with hypertension and obesity IOP increased with 2.5 mmHg.

  5. Two Phase 3 Clinical Trials Comparing the Safety and Efficacy of Netarsudil to Timolol in Patients With Elevated Intraocular Pressure: Rho Kinase Elevated IOP Treatment Trial 1 and 2 (ROCKET-1 and ROCKET-2).

    Science.gov (United States)

    Serle, Janet B; Katz, L Jay; McLaurin, Eugene; Heah, Theresa; Ramirez-Davis, Nancy; Usner, Dale W; Novack, Gary D; Kopczynski, Casey C

    2018-02-01

    To evaluate the efficacy and ocular and systemic safety of netarsudil 0.02% ophthalmic solution, a rho-kinase inhibitor and norepinephrine transporter inhibitor, in patients with open-angle glaucoma and ocular hypertension. Double-masked, randomized noninferiority clinical trials: Rho Kinase Elevated IOP Treatment Trial 1 and 2 (ROCKET-1 and ROCKET-2). After a washout of all pre-study ocular hypotensive medications, eligible patients were randomized to receive netarsudil 0.02% once daily (q.d.), timolol 0.5% twice a day (b.i.d.), and (ROCKET-2 only) netarsudil 0.02% b.i.d. Data through 3 months from both studies are provided in this report. Enrolled into the 2 studies were 1167 patients. Treatment with netarsudil q.d. produced clinically and statistically significant reductions from baseline intraocular pressure (P ROCKET-2, primary outcome measure and population, ROCKET-1, post hoc outcome measure). Netarsudil b.i.d. was also noninferior to timolol (ROCKET-2). The most frequent adverse event was conjunctival hyperemia, the incidence of which ranged from 50% (126/251, ROCKET-2) to 53% (108/203, ROCKET-1) for netarsudil q.d., 59% (149/253, ROCKET-2) for netarsudil b.i.d., and 8% (17/208, ROCKET-1) to 11% (27/251, ROCKET-2) for timolol (P < .0001 for netarsudil vs timolol). In 2 large, randomized, double-masked trials reported here, once-daily dosing of netarsudil 0.02% was found to be effective and well tolerated for the treatment of patients with ocular hypertension and open-angle glaucoma. The novel pharmacology and aqueous humor dynamic effects of this molecule suggest it may be a useful addition to the armamentarium of ocular hypotensive medications. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  6. Factors affecting intraocular pressure in lions.

    Science.gov (United States)

    Ofri, Ron; Steinmetz, Andrea; Thielebein, Jens; Horowitz, Igal H; Oechtering, Gerhard; Kass, Philip H

    2008-07-01

    The aim of this study was to conduct a detailed analysis of the relationship between age and intraocular pressure (IOP) in lions. Tonometry was conducted in 33 lions aged 5 days to 80 months. Age was significantly associated with IOP (Plions 1 year old, respectively. IOP linearly rose with age during the first 20 months of life, plateaued until approximately 40 months, and then gradually declined (r=0.85). Age-related changes in IOP were highly correlated with ultrasonographic measurements of intraocular dimensions (r > or = 0.72), and may be a determinant factor in developmental ocular growth. The dramatic rise in IOP of young lions is similar to that observed in children, but has not been previously demonstrated in animals. Significant IOP differences between lion sub-species were also demonstrated.

  7. The effect of increased intra-abdominal pressure on orbital subarachnoid space width and intraocular pressure

    Directory of Open Access Journals (Sweden)

    Su-meng Liu

    2018-01-01

    Full Text Available In accordance with the trans-lamina cribrosa pressure difference theory, decreasing the trans-lamina cribrosa pressure difference can relieve glaucomatous optic neuropathy. Increased intracranial pressure can also reduce optic nerve damage in glaucoma patients, and a safe, effective and noninvasive way to achieve this is by increasing the intra-abdominal pressure. The purpose of this study was to observe the changes in orbital subarachnoid space width and intraocular pressure at elevated intra-abdominal pressure. An inflatable abdominal belt was tied to each of 15 healthy volunteers, aged 22–30 years (12 females and 3 males, at the navel level, without applying pressure to the abdomen, before they laid in the magnetic resonance imaging machine. The baseline orbital subarachnoid space width around the optic nerve was measured by magnetic resonance imaging at 1, 3, 9, and 15 mm behind the globe. The abdominal belt was inflated to increase the pressure to 40 mmHg (1 mmHg = 0.133 kPa, then the orbital subarachnoid space width was measured every 10 minutes for 2 hours. After removal of the pressure, the measurement was repeated 10 and 20 minutes later. In a separate trial, the intraocular pressure was measured for all the subjects at the same time points, before, during and after elevated intra-abdominal pressure. Results showed that the baseline mean orbital subarachnoid space width was 0.88 ± 0.1 mm (range: 0.77–1.05 mm, 0.77 ± 0.11 mm (range: 0.60–0.94 mm, 0.70 ± 0.08 mm (range: 0.62–0.80 mm, and 0.68 ± 0.08 mm (range: 0.57–0.77 mm at 1, 3, 9, and 15 mm behind the globe, respectively. During the elevated intra-abdominal pressure, the orbital subarachnoid space width increased from the baseline and dilation of the optic nerve sheath was significant at 1, 3 and 9 mm behind the globe. After decompression of the abdominal pressure, the orbital subarachnoid space width normalized and returned to the baseline value. There was no

  8. The effect of increased intra-abdominal pressure on orbital subarachnoid space width and intraocular pressure.

    Science.gov (United States)

    Liu, Su-Meng; Wang, Ning-Li; Zuo, Zhen-Tao; Chen, Wei-Wei; Yang, Di-Ya; Li, Zhen; Cao, Yi-Wen

    2018-02-01

    In accordance with the trans-lamina cribrosa pressure difference theory, decreasing the trans-lamina cribrosa pressure difference can relieve glaucomatous optic neuropathy. Increased intracranial pressure can also reduce optic nerve damage in glaucoma patients, and a safe, effective and noninvasive way to achieve this is by increasing the intra-abdominal pressure. The purpose of this study was to observe the changes in orbital subarachnoid space width and intraocular pressure at elevated intra-abdominal pressure. An inflatable abdominal belt was tied to each of 15 healthy volunteers, aged 22-30 years (12 females and 3 males), at the navel level, without applying pressure to the abdomen, before they laid in the magnetic resonance imaging machine. The baseline orbital subarachnoid space width around the optic nerve was measured by magnetic resonance imaging at 1, 3, 9, and 15 mm behind the globe. The abdominal belt was inflated to increase the pressure to 40 mmHg (1 mmHg = 0.133 kPa), then the orbital subarachnoid space width was measured every 10 minutes for 2 hours. After removal of the pressure, the measurement was repeated 10 and 20 minutes later. In a separate trial, the intraocular pressure was measured for all the subjects at the same time points, before, during and after elevated intra-abdominal pressure. Results showed that the baseline mean orbital subarachnoid space width was 0.88 ± 0.1 mm (range: 0.77-1.05 mm), 0.77 ± 0.11 mm (range: 0.60-0.94 mm), 0.70 ± 0.08 mm (range: 0.62-0.80 mm), and 0.68 ± 0.08 mm (range: 0.57-0.77 mm) at 1, 3, 9, and 15 mm behind the globe, respectively. During the elevated intra-abdominal pressure, the orbital subarachnoid space width increased from the baseline and dilation of the optic nerve sheath was significant at 1, 3 and 9 mm behind the globe. After decompression of the abdominal pressure, the orbital subarachnoid space width normalized and returned to the baseline value. There was no significant difference in the

  9. Implantable intraocular pressure monitoring systems: Design considerations

    KAUST Repository

    Arsalan, Muhammad

    2013-12-01

    Design considerations and limitations of implantable Intraocular Pressure Monitoring (IOPM) systems are presented in this paper. Detailed comparison with the state of the art is performed to highlight the benefits and challenges of the proposed design. The system-on-chip, presented here, is battery free and harvests energy from incoming RF signals. This low-cost design, in standard CMOS process, does not require any external components or bond wires to function. This paper provides useful insights to the designers of implantable wireless sensors in terms of design choices and associated tradeoffs. © 2013 IEEE.

  10. Intraocular pressure instability after 23-gauge vitrectomy.

    Science.gov (United States)

    Singh, Christopher N; Iezzi, Raymond; Mahmoud, Tamer H

    2010-04-01

    The purpose of this study was to describe outcomes, trends, risk factors, and protective factors for intraocular pressure (IOP) spikes in patients undergoing 23-gauge pars plana vitrectomy. A retrospective review in an academic institution was performed on all eyes undergoing 23-gauge vitrectomy with at least 1-month follow-up. The main outcome measures included IOP and operative complications. Ninety-seven eyes of 93 patients were included. Intraocular pressure spikes >22 in the first month occurred in 73% of eyes with or suspect for glaucoma versus 46% of eyes without (P = 0.017); 76% of eyes with a gas fill versus 44% of eyes with a fluid fill (P = 0.0036); and 21% of eyes started on IOP-lowering drops on postoperative day 1 versus 49% of eyes who were not (P = 0.0033). Complications included retinal tears (3%), intraoperative retinal detachment (2%), and postoperative retinal detachment (2%). Fifteen percent of eyes required suturing of at least one sclerotomy. There were no cases of postoperative hypotony or endophthalmitis. Patients with or suspect for glaucoma or those with a gas fill may be at risk for high postoperative IOP during the first month. Aggressive early treatment of IOP may prevent IOP spikes in the early postoperative period.

  11. Changes of intraocular pressure during experimental vitrectomy.

    Science.gov (United States)

    Kim, Seung Hoon; Choi, Kyung Seek

    2012-08-01

    To compare the infusion pressure shown by a vitrectomy device with the actual intraocular pressure (IOP) observed during pars plana vitrectomy. Furthermore, we evaluated the effects of variable parameters on the actual IOP during vitrectomy surgery. Porcine eyes were obtained within 24 h of slaughter. Actual IOP was measured by a digital manometer during vitrectomy using the vented gas forced infusion (VGFI) system, as well as the gravity system. We analyzed the actual IOP according to the groups divided by remnant volume of infusion fluid: (500 ml; control group, 250, 125, and 50 ml). Finally, actual IOP was determined after changing variable parameters such as cutting rate, vacuum pressure, and the VGFI setting. Settings for a VGFI system and pressure supplied by a gravity system significantly correlated with actual IOP (r = 0.99, p = 0.0001; r = 0.99, and p = 0.0001). Actual IOP declined with decreasing volume of infusion fluid. If the volume of infusion fluid was pressure affected actual IOP. Infusion pressure shown by the vitrectomy device was similar to actual IOP in porcine eyes. However, volume of infusion fluid and variable parameters could change the actual IOP during pars plana vitrectomy. Our results may help to optimize the ideal parameters such as infusion pressure, vacuum pressure, and cutting rate of vitrectomy systems used to treat vitreoretinal diseases.

  12. Tear Film Functions and Intraocular Pressure Changes in Pregnancy.

    African Journals Online (AJOL)

    AJRH Managing Editor

    employed to assess visual acuity, tear break up time (TBUT), Schirmer's test (ST), intraocular pressure (IOP) on all subjects. The mean values for IOP ... Keywords: Tear break-up time, Schirmer's test, intraocular pressure, pregnancy. Résumé ..... Goldich Y, Cooper M, Barkana Y, Tovbin J, Lee Ovadia. K, Avni I, Zadok D.

  13. Tear production and intraocular pressure in canine eyes with ...

    African Journals Online (AJOL)

    Tear production and intraocular pressure in canine eyes with corneal ulceration. David L. Williams, Philippa Burg. Abstract. This study aimed to evaluate changes in lacrimation and intraocular pressure (IOP) in dogs with unilateral corneal ulceration using the Schirmer tear test (STT) and rebound (TonoVet®) tonometry.

  14. Intraocular Pressure Increases After Intraarticular Knee Injection With Triamcinolone but Not Hyaluronic Acid.

    Science.gov (United States)

    Taliaferro, Kevin; Crawford, Alexander; Jabara, Justin; Lynch, Jonathan; Jung, Edward; Zvirbulis, Raimonds; Banka, Trevor

    2018-03-09

    Intraarticular steroid injections are a common first-line therapy for severe osteoarthritis, which affects an estimated 27 million people in the United States. Although topical, oral, intranasal, and inhalational steroids are known to increase intraocular pressure in some patients, the effect of intraarticular steroid injections on intraocular pressure has not been investigated, to the best of our knowledge. If elevated intraocular pressure is sustained for long periods of time or is of sufficient magnitude acutely, permanent loss of the visual field can occur. How does intraocular pressure change 1 week after an intraarticular knee injection either with triamcinolone acetonide or hyaluronic acid? A nonrandomized, nonblinded prospective cohort study was conducted at an outpatient, ambulatory orthopaedic clinic. This study compared intraocular pressure elevation before and 1 week after intraarticular knee injection of triamcinolone acetonide versus hyaluronic acid for management of primary osteoarthritis of the knee. Patients self-selected to be injected in their knee with either triamcinolone acetonide or hyaluronic acid before being informed of the study. The primary endpoint was intraocular pressure elevation of ≥ 7 mm Hg 1 week after injection. This cutoff is determined as the minimum significant pressure change in the ophthalmology literature recognized as an intermediate responder to steroids. Intraocular pressure was measured using a handheld Tono-Pen® applanation device. This device is frequently used in intraocular pressure measurement in clinical and research settings; 10 sequential measurements are obtained and averaged with a confidence interval. Only measurements with a 95% confidence interval were used. Over a 6-month period, a total of 96 patients were approached to enroll in the study. Sixty-two patients out of 96 approached (65%) agreed. Thirty-one (50%) were injected with triamcinolone and 31 (50%) were injected with hyaluronic acid. Patients

  15. The influence of retrobulbar adipose tissue volume upon intraocular pressure in obesity

    Directory of Open Access Journals (Sweden)

    Stojanov Oliver

    2013-01-01

    Full Text Available Background/Aim. It is known that glaucoma is associated with elevated intraocular pressure and obesity, yet the precise etiology remains unclear. The aim of this study was to determine whether there is a potential causality between the volume of retrobulbar adipose tissue and the level of intraocular pressure in obese subjects compared with non-obese. Methods. A total of 100 subjects were divided according to the body mass index (BMI, into two groups: normal weight (n = 50, BMI = 18-24.9 kg/m2 and obese (n = 50, BMI ≥ 30 kg/m2 subjects. Anthropometric measurements, body composition analysis, measurement of intraocular pressure, as well as magnetic resonance imaging (MRI of the head at the level of the optic nerve, and the derived retrobulbar adipose tissue volume, were undertaken in all subjects. Results. The obese subjects, as compared with normal weight ones, had a significantly higher mean retrobulbar adipose tissue volume (6.23 cm3 vs 4.85 cm3, p < 0.01 and intraocular pressure (15.96 mmHg vs 12.99 mmHg, p < 0.01. Furthermore, intraocular pressure correlated positively with retrobulbar adipose tissue volume. Conclusion. In obese people, elevated intraocular pressure may be caused by changes in ocular blood flow, affected by the physical pressure exerted by higher retrobulbar adiposity, and/or by internal vascular changes secondary to complications of obesity. These findings indicate the need for more frequent measurement of intraocular pressure in obese individuals to earlier detect glaucoma, and in so doing prevent irreversible blindness.

  16. Effect of plasma colloid osmotic pressure on intraocular pressure during haemodialysis

    OpenAIRE

    Tokuyama, T.; Ikeda, T.; Sato, K.

    1998-01-01

    BACKGROUND—In a previous case report, it was shown that an increase in plasma colloid osmotic pressure induced by the removal of fluid during haemodialysis was instrumental in decreasing intraocular pressure. The relation between changes in intraocular pressure, plasma osmolarity, plasma colloid osmotic pressure, and body weight before and after haemodialysis is evaluated.
METHODS—Intraocular pressure, plasma osmolarity, plasma colloid osmotic pressure, and body weight were evaluated before a...

  17. Relationship between homocysteine and intraocular pressure in men and women: A population-based study.

    Science.gov (United States)

    Leibovitzh, Haim; Cohen, Eytan; Levi, Amos; Kramer, Michal; Shochat, Tzippy; Goldberg, Elad; Krause, Ilan

    2016-09-01

    The relationship between homocysteine levels and glaucoma has been questioned in previous studies without conclusive results. In the current study, we assessed the relationship between homocysteine levels and intraocular pressure which is one of the main factors in the development of glaucoma in men and women.A retrospective cross-sectional analysis of a database from a screening center in Israel which assessed 11,850 subjects, within an age range 20 to 80 years. The relationship between homocysteine and intraocular pressure has been investigated by comparing intraocular pressure in subjects with elevated and normal homocysteine and by comparing homocysteine levels in subjects with elevated and normal intraocular pressure. In addition, we compared the levels of homocysteine in subjects with and without a confirmed diagnosis of glaucoma.The mean IOP (±SD) in subjects with normal homocysteine levels(≤15 μmol/L) was 13.2 ± 2.3 mm Hg and 13.4 ± 2.4 mm Hg in those with high homocysteine levels (>15 μmol/L) (P homocysteine levels (±SD) in subjects with normal intraocular pressure of ≤ 21 mm Hg was 11.7 ± 5.5 μmol/L and 12.09 ± 3.43 μmol/L in those with elevated intraocular pressure (P = 0.4, 95%CI 1.1-1.8). Mean homocysteine levels (±SD) in subjects with glaucoma were 11.2 ± 3.5 μmol/L compared to 11.7 ± 5.5 μmol/L in subjects without glaucoma and normal intraocular pressure ≤ 21 mm Hg (P = 0.4, 95% CI 1.2-2.1).The current study displays no clinical correlation between the homocysteine level and the intraocular pressure. Homocysteine may not be used as a predictive parameter to recognize those subjects prone to develop elevated intraocular pressure.

  18. A mouse ocular explant model that enables the study of living optic nerve head events after acute and chronic intraocular pressure elevation: Focusing on retinal ganglion cell axons and mitochondria.

    Science.gov (United States)

    Kimball, Elizabeth C; Pease, Mary E; Steinhart, Matthew R; Oglesby, Ericka N; Pitha, Ian; Nguyen, Cathy; Quigley, Harry A

    2017-07-01

    We developed an explant model of the mouse eye and optic nerve that facilitates the study of retinal ganglion cell axons and mitochondria in the living optic nerve head (ONH) in an ex vivo environment. Two transgenic mouse strains were used, one expressing yellow fluorescent protein in selected axons and a second strain expressing cyan fluorescent protein in all mitochondria. We viewed an explanted mouse eye and optic nerve by laser scanning microscopy at and behind the ONH, the site of glaucoma injury. Explants from previously untreated mice were studied with the intraocular pressure (IOP) set artificially at normal or elevated levels for several hours. Explants were also studied from eyes that had undergone chronic IOP elevation from 14 h to 6 weeks prior to ex vivo study. Image analysis in static images and video of individual mitochondria or axonal structure determined effects of acute and chronic IOP elevation. At normal IOP, fluorescent axonal structure was stable for up to 3 h under ex vivo conditions. After chronic IOP elevation, axonal integrity index values indicated fragmentation of axon structure in the ONH. In mice with fluorescent mitochondria, the normal density decreased with distance behind the ONH by 45% (p = 0.002, t-test). Density increased with prior chronic IOP elevation to 21,300 ± 4176 mitochondria/mm 2 compared to control 16,110 ± 3159 mitochondria/mm 2 (p = 0.025, t-test), but did not increase significantly after 4 h, acute IOP elevation (1.5% decrease in density, p = 0.83, t-test). Mean normal mitochondrial length of 2.3 ± 1.4 μm became 13% smaller after 4 h of IOP elevation ex vivo compared to baseline (p = 0.015, t-test, N-10). Normal mitochondrial speed of movement was significantly slower in the anterograde direction (towards the brain) than retrograde, but there were more mitochondria in motion and traveling longer lengths in anterograde direction. The percent of mitochondria in motion decreased by >50

  19. Relation between intraocular pressure and size of transverse sinuses

    Energy Technology Data Exchange (ETDEWEB)

    Kantarci, Mecit; Onbas, Omer; Alper, Fatih; Okur, Adnan [Atatuerk University, Department of Radiology, Medical Faculty, Erzurum (Turkey); Dane, Senol; Gumustekin, Kenan [Atatuerk University, Department of Physiology, Medical Faculty, Erzurum (Turkey); Aslankurt, Murat [Atatuerk University, Department of Ophtalmatology, Medical Faculty, Erzurum (Turkey); Yazici, Ahmet Taylan [Beyoglu Goez Egitim ve Arastirma Hastanesi, Istanbul (Turkey)

    2005-01-01

    There are asymmetries in the sizes of transverse sinus and intraocular pressure. The purpose of this study was to investigate possible relationships between the asymmetry of transverse sinuses in TOF MR venography and intraocular pressures of right and left eyes. In this study, subjects were 63 male and 42 female medical school students, aged 18-21 years (mean{+-}SD; 19.72{+-}0.67 years). Subjects with neurological and ophthalmologic disease, particularly dural sinus thrombosis, myopia, trauma and glaucoma, were excluded the study. Subjects were divided into five groups according to the magnitudes of the right- and left-transverse sinuses in MR venography results. There is a functional relation between intraocular pressures of the right and left eyes and asymmetry of the transverse sinus. If the transverse sinus on one side is larger and its venous drainage is greater, the intraocular pressure of the eye on this side is lower. It can be speculated that the transverse sinus size may be associated with pathogenesis of diseases with increased intraocular pressure such as glaucoma. We aim to determine the relation between the size and drainage of transverse sinuses in TOF MR venography and intraocular pressure in patients with open-angle glaucoma in our next study. (orig.)

  20. Effect of phacoemulsification on vision and intraocular pressure and corneal astigmatism

    Directory of Open Access Journals (Sweden)

    Jing Yu

    2017-06-01

    Full Text Available Objective: To explore the effect of phacoemulsification in combined with intraocular lens implantation incision site selection on the visual function, intraocular pressure, and corneal astigmatism in patients with cataract. Methods: A total of 72 patients (85 eyes with cataract who were admitted in our hospital from April, 2015 to October, 2016 were included in the study. All the patients were performed with phacoemulsification in combined with intraocular lens implantation. The patients were divided into the observation group (n=36, 43 eyes and the control group (n=36, 42 eyes according to different surgical incision sites. A transparent corneal incision with a length of 3.0 mm was made along the meridian axial position with the maximum corneal refractive power in the observation, while a transparent corneal incision with a length of 3.0 mm was made above the temple or nose in the control group. Routine disposition and follow-up visit were given for the patients in the two groups after operation. BCVA, intraocular pressure, corneal astigmatism, and corneal endothelial cell count in the two groups before and after operation were compared. Results: BCVA after operation in the two groups was significantly elevated, while the corneal endothelial cell count was significantly reduced, but the comparison of BCVA and corneal endothelial cell count between the two groups was not statistically significant. The intraocular pressure after operation in the two groups was elevated first and reduced later. The intraocular pressure 2 h and 1 d after operation was significantly elevated when compared with before operation. The intraocular pressure 2 d after operation was not significantly different from that before operation. The comparison of intraocular pressure at each timing point after operation between the two groups was not statistically significant. The corneal astigmatism after operation in the two groups was elevated first and reduced later. The

  1. ARHGEF12 influences the risk of glaucoma by increasing intraocular pressure

    NARCIS (Netherlands)

    H. Springelkamp (Henriët); A.I. Iglesias González (Adriana); G. Cuellar-Partida (Gabriel); N. Amin (Najaf); K.P. Burdon (Kathryn); E.M. van Leeuwen (Elisa); P. Gharahkhani (Puya); A. Mishra (Aniket); S.J. van der Lee (Sven); A.W. Hewit (Alex); F. Rivadeneira Ramirez (Fernando); A.C. Viswanathan (Ananth); R.C.W. Wolfs (Roger); N.G. Martin (Nicholas); W.D. Ramdas (Wishal); L.M.E. van Koolwijk (Leonieke); C.E. Pennell (Craig E.); J.R. Vingerling (Hans); J.E. Mountain (Jenny E.); A.G. Uitterlinden (André); A. Hofman (Albert); P. Mitchell (Paul); H.G. Lemij (Hans); J.J. Wang (Jie Jin); C.C.W. Klaver (Caroline); D.A. Mackey (David); J.E. Craig (Jamie E.); C.M. van Duijn (Cornelia); S. MacGregor (Stuart)

    2015-01-01

    textabstractPrimary open-angle glaucoma (POAG) is a blinding disease. Two important risk factors for this disease are a positive family history and elevated intraocular pressure (IOP), which is also highly heritable. Genes found to date associated with IOP and POAG are ABCA1, CAV1/CAV2, GAS7 and

  2. The elevation of intraocular pressure is associated with apoptosis and increased immunoreactivity for nitric oxide synthase in rat retina whereas the effectiveness of retina derived relaxing factor is unaffected.

    Science.gov (United States)

    Takır, Selçuk; Gürel-Gürevin, Ebru; Toprak, Ayça; Demirci-Tansel, Cihan; Uydeş-Doğan, B Sönmez

    2016-04-01

    Glaucoma is a progressive ocular disease that stands in the upper rank for the cause of blindness in worldwide. In the present study, we aimed to elucidate the possible disturbances occurred in the layers of retina due to an increase in intraocular pressure (IOP) and to verify the effectiveness of retina derived relaxing factor, i.e., RRF in this pathologic condition. The increase in IOP was induced by cauterization of the three of episcleral veins simultaneously in rats. After 8 weeks period, the retinas excised from the vein cauterized eyes were evaluated for the possible histopathological and ultrastructural alterations as well as for the relaxing effects on isolated bovine retinal and rat mesenteric arteries, in comparison with the retinas obtained from contralateral sham-operated eyes. In the retinas of IOP-elevated eyes, profound morphological deteriorations were determined in the ganglion and outer nuclear cell layers which were associated with an increased number of TUNEL positive cells in the ganglion and inner nuclear cell layers. Increased immunohistochemical stainings for three isoforms of nitric oxide synthase (NOS) were defined in almost all layers of the retinas of IOP-elevated eyes, in which eNOS was abundant particularly in the inner plexiform and ganglion cell layers. An irregular basal folding of retinal pigment epithelium (RPE) and an increased inter lamellar space of photoreceptor cell layer furtherly characterized the prominent degeneration of those layers in the retinas of IOP-elevated eyes. On the other hand, the relaxing effects of the retina obtained from IOP-elevated eyes were determined to be unchanged on the retinal and mesenteric arteries precontracted either with prostaglandin F2α (PGF2α, 30 μM) or potassium chloride (K(+), 100 mM), when compared with the relaxations of control retina obtained from contralateral sham-operated eyes. Overall, these findings suggested that the elevation of IOP induces prominent structural changes in

  3. Pharmacotherapy of intraocular pressure: part I. Parasympathomimetic, sympathomimetic and sympatholytics.

    Science.gov (United States)

    Costagliola, Ciro; dell'Omo, Roberto; Romano, Mario R; Rinaldi, Michele; Zeppa, Lucia; Parmeggiani, Francesco

    2009-11-01

    Elevated intraocular pressure (IOP) has been recognized as the major risk factor for the development of glaucoma and a wide range of options are now available to reduce it: medical treatment, laser, filtering, or cyclodestructive surgery (alone or in combination). All these modalities act by decreasing eye pressure and, thereby, protecting the optic nerve head from a mechanic direct and/or vascular indirect insult. Topical medical therapy represents the first-choice treatment and, in most cases, it effectively controls IOP, avoiding the occurrence of further optic nerve damage. All medications lower IOP in two main ways: decreasing the production of aqueous humour or by increasing its outflow from the eye. Consequently, antiglaucoma drugs either suppress aqueous humour formation (beta-adrenergic antagonists, carbonic anhydrase inhibitors, and alpha-2-adrenergic agonists) or raise aqueous humour outflow throughout the conventional (e.g., pilocarpine) or uveoscleral (prostaglandin FP receptor agonists, and prostamides) route. In addition, fixed and unfixed combinations of antiglaucoma compounds have also been available for patients requiring more than one type of medication. This review, which is part one of two (please see Expert Opinion on Pharmacotherapy 10 (17)) briefly considers the characteristics of sympathomimetic, sympatholytics and parasympathomimetic commonly employed in the medical treatment of glaucoma, mainly the primary open-angle form, focusing the discussion on the clinical evidence supporting the use of these three classes of compound.

  4. Telemedicine in the control of intra-ocular pressure.

    Science.gov (United States)

    Michelson, G; Striebel, W; Prihoda, W; Schmidt, V

    2000-01-01

    Glaucoma is one of the most common causes of blindness in the Western world and a major risk factor is increased intra-ocular pressure. We therefore used telemedicine in its control. Patients measured their intra-ocular pressure several times a day with a portable instrument and the values were then entered into a portable digital assistant. These data were transmitted by a modem to a central server. If the intra-ocular pressure was pathologically high, an email message was automatically sent to the ophthalmologist. The pressure curve, including a statistical analysis, was displayed in an easily readable chart format. Ten patients with glaucoma participated in a trial. Self-tonometry with telemedicine enabled continuous evaluation of the patient by the ophthalmologist. This approach offered the advantage of controlling the treatment remotely. Advantages for the patient were that the measurements were easily done at home under normal conditions, and the patient could control when the measurement and data transmission would be performed. Telemedicine is a cost-effective technique enabling the early diagnosis of pathologically increased intra-ocular pressure.

  5. Intraocular pressure and visual acuity across the phases of the ...

    African Journals Online (AJOL)

    Context: Available literature suggests that the pattern of variation in intraocular pressure (IOP) in different phases of the menstrual cycle is inconsistent. Results from studies on the effects of oestrogen and progesterone alone or in combination, on IOP have been conflicting. Aim: To determine the pattern of changes in IOP ...

  6. Comparison of Intraocular Pressure Reduction of Initial and Adjunct ...

    African Journals Online (AJOL)

    baseline, 60 min post procedure, days 1, 7, 30, 90, and 180. Results: Mean ... frequency‑doubled, Q‑switched neodymium yttrium aluminum garnet laser .... Day 90. 3.5. 1.9. Day 180. 2.8. 2.7. IOP: Intraocular pressure, SLT: Selective laser trabeculoplasty. Table 4: Percentage IOP reduction, values in percentage. Initial SLT.

  7. Investigation of the relationship between intraocular pressure and ...

    African Journals Online (AJOL)

    In a randomized prospective study of volunteers attending Abia State University Optometry Clinic, Uturu, 100 healthy subjects of either sex were enlisted into study, ages 17-39yrs (mean 22-9+2.4) and body weight56to 02kg, in order to establish the association between total body water and intraocular pressure.

  8. Comparison of intraocular pressure reduction of initial and adjunct ...

    African Journals Online (AJOL)

    Objective: The objective was to compare the intraocular pressure (IOP) lowering effect of selective laser trabeculoplasty (SLT) as initial and adjunct therapy in primary open angle glaucoma (POAG). Subjects and Methods: Retrospective chart review of POAG patients who had SLT either as initial or adjunct therapy over a ...

  9. Intraocular Pressure Changes During Ramadan Fasting: Effect of ...

    African Journals Online (AJOL)

    Background: Ramadan fasting (RF) alters many systemic milieus. Dehydration from fasting may cause weight loss, while sedentary lifestyle of some Muslims during fasting results in weight gain. RF is associated with low intraocular pressure (IOP). We aim to find out changes in IOP and its relationship to weight changes ...

  10. Short Term Effect of Exercise on Intraocular Pressure of Ocular ...

    African Journals Online (AJOL)

    Aim: Numerous international studies have indicated that several physiological changes can influence the intraocular pressure (IOP) of subjects. In order to assess visual health status through physiological changes, the effects of rest and exercise on IOP were investigated in ocular hypertensive subjects and their ...

  11. A common humoral background of intraocular and arterial blood pressure dysregulation.

    Science.gov (United States)

    Skrzypecki, Janusz; Grabska-Liberek, Iwona; Przybek, Joanna; Ufnal, Marcin

    2018-03-01

    It has been postulated that intraocular pressure, an important glaucoma risk factor, correlates positively with arterial blood pressure (blood pressure). However, results of experimental and clinical studies are often contradictory. It is hypothesized that, in some hypertensive patients, disturbances in intraocular pressure regulation may depend on biological effects of blood borne hormones underlying a particular type of hypertension, rather than on blood pressure level itself. This review compares the effects of hormones on blood pressure and intraocular pressure, in order to identify a hormonal profile of hypertensive patients with an increased risk of intraocular pressure surge. The PUBMED database was searched to identify pre-clinical and clinical studies investigating the role of angiotensin II, vasopressin, adrenaline, noradrenaline, prostaglandins, and gaseous transmitters in the regulation of blood pressure and intraocular pressure. Studies included in the review suggest that intraocular and blood pressures often follow a different pattern of response to the same hormone. For example, vasopressin increases blood pressure, but decreases intraocular pressure. In contrast, high level of nitric oxide decreases blood pressure, but increases intraocular pressure. Arterial hypertension is associated with altered levels of blood borne hormones. Contradicting results of studies on the relationship between arterial hypertension and intraocular pressure might be partially explained by diverse effects of hormones on arterial and intraocular pressures. Further studies are needed to evaluate if hormonal profiling may help to identify glaucoma-prone patients.

  12. Effect of pegaptanib sodium 0.3 mg intravitreal injections (Macugen) in intraocular pressure

    DEFF Research Database (Denmark)

    Boyer, David S; Goldbaum, Mauro; Leys, Anita M

    2014-01-01

    OBJECTIVE: To assess the rate of pegaptanib-associated sustained intraocular pressure (IOP) elevation. METHODS: A posthoc analysis was conducted on all IOP measurements, except the immediate 30-min postinjection, from all subjects randomised to pegaptanib 0.3 mg or sham injections continuously in...... lowering medication added during the course of the study. No subject required glaucoma surgery. CONCLUSIONS: In V.I.S.I.O.N., after 2 years, there was no evidence of sustained IOP elevation associated with pegaptanib 0.3 mg use. TRIAL REGISTRATION NUMBER: NCT00321997....

  13. Effect of pegaptanib sodium 0.3 mg intravitreal injections (Macugen) in intraocular pressure: posthoc analysis from VISION study

    NARCIS (Netherlands)

    Boyer, David S.; Goldbaum, Mauro; Leys, Anita M.; Starita, Carla; Blumenkranz, M.; Buyse, M.; Goldberg, M.; Gragoudas, E. S.; Miller, J.; Schwartz, S. D.; Singerman, L.; Yannuzzi, L.; Adamis, A. P.; Guyer, D. R.; O'Shaughnessy, D.; de Gronckel, S.; Fesneau, G.; Quinaux, E.; Tremolet, D.; Wang, K.; Brailey, A.; Finman, J.; Ting, N.; Bressler, N. M.; Bressler, S. B.; Denblow, R.; Schein, O. D.; Seabrook, S.; Solomon, S.; Schachat, A. P.; Philips, D.; Altaweel, M.; Davis, M. D.; Blodi, Ba; Danis, R. P.; Ip, M. S.; Hiner, C.; Elledge, J.; Webster, M.; Hannan, C.; Ficken, J.; Alexander, S.; Neider, M.; Wabers, H.; Vargo, P.; Lambert, E.; Kastorff, L.; Carr, A.; Shkiele, A.; Baliker, J.; Guymer, R.; Constable, I.; Arnold, J.; Sarks, S.; Chang, A.; Gillies, M.; Mitchell, P.; Haas, A.; Stur, M.; Leys, A.; Moreira, C.; Portella, E.; de Avila, M.; Taleb, Ac; Lavinsky, J.; Lavinsky, D.; Farah, M. E.; Williams, G.; Leonard, B.; Garcia, R.; Maberley, D.; Lopez, Jm; Rodriguez, F. J.; Fiser, I.; Larsen, M.; Korobelnik, J.-F.; Soubrane, G.; Koenig, F.; Gaudric, A.; Dithmar, S.; Holz, Fg; Joussen, A.; Kirchhof, B.; Wiedemann, P.; Pauleikhoff, D.; Schneider, U.; Suveges, I.; Gyory, J.; Pollack, A.; Loewenstein, A.; Rosenblatt, I.; Giovannini, A.; Menchini, U.; Brancato, R.; Cardillo Piccolino, F.; Grignolo, F. M.; Bandello, F.; Schlingemann, R. O.; Deutman, A.; Kaluzny, J.; Pecold, K.; Cunha-Vaz, J.; da Silva, R.; Ruiz Moreno, J. M.; Mones, J.; Figueroa, M.; Pournaras, C.; Zografos, L.; Lois, N.; Chakravarthy, U.; Hykin, P.; Chisholm, I.; Johnson, M. W.; Marcus, D. M.; Mandava, N.; Haller, Ja; Cangemi, F.; Boyer, D.; Kim, I.; Loewenstein, J.; Heier, J.; Reichel, E.; Falcone, P. M.; Weissgold, D. J.; Conway, B. P.; Garfinkel, R.; Glaser, B.; Lyon, A. T.; Lewis, H.; Wells, J. A.; Wilcox, L.; Fish, G.; Eliott, D.; Fekrat, S.; Taney, B.; Eaton, A. M.; Deramo, V.; Wroblewski, J.; Tom, D.; Chow, D. R.; Orth, D. H.; Packo, K. H.; Holz, E.; Mieler, W.; Kuppermann, B.; Sabates, N.; Cummings, H.; Pendergast, S. D.; Gonzales, C.; Lim, J. I.; Charles, S.; Sanislo, S.; Rosenfeld, P.; Connor, T.; Cantrill, H.; Willson, R.; Bailey-Freund, K.; Rosen, R.; Leonard, R.; Brucker, A.; Ho, A.; Sneed, S.; Friberg, T.; Klein, M.; Tornambe, P.; Stoller, G.; Capone, A.; Bernstein, P. S.; McDonald, H. R.; Schatz, H.; Johnson, R. N.; Nanda, M.; Avery, R.; Wong, K.; Grizzard, W. S.; Higgins, P.; Hudson, H.; Joffe, L.; Varenhorst, M.; Slusher, M. M.; Betts, F.; Cunningham, E.; Curtiss, K.; Harrison, E.; Katz, B.; Masonson, H. N.; DeMarco, R.; Beals, C.; Patel, M.; Rodriguez, I.; Starita, C.

    2014-01-01

    Objective To assess the rate of pegaptanib-associated sustained intraocular pressure (IOP) elevation. Methods A posthoc analysis was conducted on all IOP measurements, except the immediate 30-min postinjection, from all subjects randomised to pegaptanib 0.3 mg or sham injections continuously in the

  14. Genome-wide analysis of multi-ancestry cohorts identifies new loci influencing intraocular pressure and susceptibility to glaucoma

    NARCIS (Netherlands)

    Hysi, Pirro G.; Cheng, Ching-Yu; Springelkamp, Henriet; Macgregor, Stuart; Bailey, Jessica N. Cooke; Wojciechowski, Robert; Vitart, Veronique; Nag, Abhishek; Hewitt, Alex W.; Hohn, Rene; Venturini, Cristina; Mirshahi, Alireza; Ramdas, Wishal D.; Thorleifsson, Gudmar; Vithana, Eranga; Khor, Chiea-Chuen; Stefansson, Arni B.; Liao, Jiemin; Haines, Jonathan L.; Amin, Najaf; Wang, Ya Xing; Wild, Philipp S.; Ozel, Ayse B.; Li, Jun Z.; Fleck, Brian W.; Zeller, Tanja; Staffieri, Sandra E.; Teo, Yik-Ying; Cuellar-Partida, Gabriel; Luo, Xiaoyan; Allingham, R. Rand; Richards, Julia E.; Senft, Andrea; Karssen, Lennart C.; Zheng, Yingfeng; Bellenguez, Celine; Xu, Liang; Iglesias, Adriana I.; Wilson, James F.; Kang, Jae H.; van Leeuwen, Elisabeth M.; Jonsson, Vesteinn; Thorsteinsdottir, Unnur; Despriet, Dominiek D. G.; Ennis, Sarah; Moroi, Sayoko E.; Martin, Nicholas G.; Jansonius, Nomdo M.; Yazar, Seyhan; Tai, E-Shyong

    2014-01-01

    Elevated intraocular pressure (IOP) is an important risk factor in developing glaucoma, and variability in IOP might herald glaucomatous development or progression. We report the results of a genome-wide association study meta-analysis of 18 population cohorts from the International Glaucoma

  15. Intraocular Pressure After 2 Hours of Small-Diameter Scleral Lens Wear.

    Science.gov (United States)

    Nau, Cherie B; Schornack, Muriel M; McLaren, Jay W; Sit, Arthur J

    2016-11-01

    Compression of episcleral veins or deformation of tissue in the Schlemm's canal beneath the landing zone of scleral lenses could elevate intraocular pressure (IOP). We examined the effect of 2 hr of small-diameter scleral lens wear on IOP. Twenty-nine participants, 29 ± 6 years old (mean ± SD) who experienced no history of eye disease or scleral lens wear, were included in the study. Each participant was fitted with a 15-mm Jupiter scleral lens on one eye (study eye). Intraocular pressure was measured in both eyes by pneumatonometry centrally on the cornea and peripherally on the sclera. The lens was then placed on one eye and was worn for 2 hr. Intraocular pressure was remeasured immediately after lens placement, at 1 and 2 hr of lens wear, and immediately after lens removal. Intraocular pressure after removal of the scleral lens was compared with IOP before placing the lens and to IOP in the control eye using paired t tests. Immediately after removing the scleral lens, mean central IOP in the study eye (13.9 ± 3.1 mm Hg) was not different from mean central IOP in the control eye (13.5 ± 2.2 mm Hg, P = 0.4) or in the same eye before lens wear (13.6 ± 1.9 mm Hg, P = 0.6). There were also no differences in IOP measured peripherally at 2 hr of lens wear (P = 0.8). Neophyte scleral lens wear of a 15-mm scleral lens for 2 hr does not increase IOP in healthy eyes.

  16. A new device to noninvasively estimate the intraocular pressure produced during ocular compression

    Directory of Open Access Journals (Sweden)

    Korenfeld MS

    2016-01-01

    Full Text Available Michael S Korenfeld,1,2 David K Dueker3 1Comprehensive Eye Care, Ltd., 2Department of Ophthalmology and Visual Sciences, Washington University, Washington, MO, USA; 3Hamad Medical Corporation, Doha, Qatar Purpose: To describe a noninvasive instrument that estimates intraocular pressure during episodes of external globe compression and to demonstrate the accuracy and reliability of this device by comparing it to the intraocular pressures simultaneously and manometrically measured in cannulated eyes. Methods: A thin fluid-filled bladder was constructed from flexible and inelastic plastic sheeting and was connected to a pressure transducer with high pressure tubing. The output of the pressure transducer was sent to an amplifier and recorded. This device was validated by measuring induced pressure in the fluid-filled bladder while digital pressure was applied to one surface, and the other surface was placed directly against a human cadaver eye or in vivo pig eye. The human cadaver and in vivo pig eyes were each cannulated to provide a manometric intraocular pressure control. Results: The measurements obtained with the newly described device were within ~5% of simultaneously measured manometric intraocular pressures in both a human cadaver and in vivo pig eye model for a pressure range of ~15–100 mmHg. Conclusion: This novel noninvasive device is useful for estimating the intraocular pressure transients induced during any form of external globe compression; this is a clinical setting where no other devices can be used to estimate intraocular pressure. Keywords: glaucoma, intraocular pressure, tonometer, ocular compression

  17. Change in Intraocular Pressure During Point-of-Care Ultrasound

    Directory of Open Access Journals (Sweden)

    Berg, Cameron

    2015-03-01

    Full Text Available Introduction: Point-of-care ocular ultrasound (US is a valuable tool for the evaluation of traumatic ocular injuries. Conventionally, any maneuver that may increase intraocular pressure (IOP is relatively contraindicated in the setting of globe rupture. Some authors have cautioned against the use of US in these scenarios because of a theoretical concern that an US examination may cause or exacerbate the extrusion of intraocular contents. This study set out to investigate whether ocular US affects IOP. The secondary objective was to validate the intraocular pressure measurements obtained with the Diaton® as compared with standard applanation techniques (the Tono-Pen®.   Methods: We enrolled a convenience sample of healthy adult volunteers. We obtained the baseline IOP for each patient by using a transpalpebral tonometer. Ocular US was then performed on each subject using a high-frequency linear array transducer, and a second IOP was obtained during the US examination. A third IOP measurement was obtained following the completion of the US examination. To validate transpalpebral measurement, a subset of subjects also underwent traditional transcorneal applanation tonometry prior to the US examination as a baseline measurement. In a subset of 10 patients, we obtained baseline pre-ultrasound IOP measurements with the Diaton® and Tono-Pen®, and then compared them.   Results: The study included 40 subjects. IOP values during ocular US examination were slightly greater than baseline (average +1.8mmHg, p=0.01. Post-US examination IOP values were not significantly different than baseline (average -0.15mmHg, p=0.42. In a subset of 10 subjects, IOP values were not significantly different between transpalpebral and transcorneal tonometry (average +0.03mmHg, p=0.07.   Conclusion: In healthy volunteer subjects, point-of-care ocular US causes a small and transient increase in IOP. We also showed no difference between the Diaton® and Tono-Pen® methods

  18. Intraocular pressure in very low birth weight preterm infants and its association with postconceptional age

    Directory of Open Access Journals (Sweden)

    Rodrigo L. Lindenmeyer

    2012-11-01

    Full Text Available OBJECTIVE: To evaluate intraocular pressure in very low birth weight preterm infants and correlate it with postconceptional age. METHODS: The intraocular pressure in a prospective cohort of very low birth weight premature infants (defined as a birth weight <1,500 g and gestational age <32 weeks admitted to Hospital de Clínicas de Porto Alegre , Brazil was evaluated weekly. The evaluated outcome was the variation in the intraocular pressure following changes in the postconceptional age (defined as the gestational age at birth plus the age in weeks at the time of examination in the weeks following preterm birth. Mixed-effects models were used for the statistical analysis to determine the intraocular pressure variation according to postconceptional age, and means and 10th and 90th percentiles were calculated for the intraocular pressure values. RESULTS: Fifty preterm infants with a mean gestational age of 29.7 ± 1.6 weeks and a mean birth weight of 1,127.7 ± 222.7 g were evaluated. The mean intraocular pressure for the entire cohort considering both eyes was 14.9 ± 4.5 mmHg, and 13.5% of all recorded intraocular pressure values were greater than 20 mmHg. The analysis revealed a mean reduction in the intraocular pressure of 0.29 mmHg for each increase in postconceptional age (p = 0.047; 95% CI: -0.58 to -0.0035. The mean intraocular pressure (P10-P90 decreased from 16.3 mmHg (10.5222.16 at 26.3 weeks to 13.1 mmHg (7.28-18.92 at 37.6 weeks of postconceptional age. CONCLUSIONS: The mean intraocular pressure in very low birth weight preterm infants was 14.9 ± 4.5 mmHg. This value decreased 0.29 mmHg per week as the postconceptional age increased.

  19. Comparison of latanoprost with fixed-combination dorzolamide and timolol in adult patients with elevated intraocular pressure: an eight-week, randomized, open-label, parallel-group, multicenter study in Latin America.

    Science.gov (United States)

    Susanna, Remo; Sussana, Remo; Sheu, Wang-Pui

    2004-05-01

    The newer ocular hypotensive agents available to treat glaucoma and ocular hypertension (OHT) include latanoprost, a prostaglandin F(2alpha) analogue, and the fixed combination of dorzolamide hydrochloride, a carbonic anhydrase inhibitor, and timolol maleate, a beta-blocker. The aim of this study was to compare the efficacy and tolerability of latanoprost with that of the fixed combination of dorzolamide and timolol over 8 weeks. This interventional, 8-week, randomized, open-label, parallel-group study was conducted at 18 centers in 6 Latin American countries. Patients with unilateral or bilateral primary open-angle, pigmentary, or exfoliative glaucoma or OHT were randomized to receive latanoprost, 1 drop in the affected eye QD (evening), or fixed-combination dorzolamide/timolol, 1 drop in the affected eye BID (morning and evening). Medications were self-administered, 1 drop per affected eye. At baseline and week 8, intraocular pressure (IOP) was measured 3 times each at 8:30 am, 10:00 am, 2:00 pm, and 5:00 pm and after the water-drinking test, which estimates the IOP peak of diurnal tension curve, performed following the 5:00 pm IOP assessment. The primary efficacy outcome was change in diurnal IOP (the mean of IOP measurements) from baseline to week 8. Adverse effect (AE) data were recorded at each visit. A total of 229 patients were randomized (latanoprost, n = 112; dorzolamide/timolol, n = 117). Mean baseline diurnal IOP values were similar between the 2 groups. Mean (SD) diurnal IOP reductions at week 8 before the water-drinking test were 6.9 (3.0) mm Hg for the latanoprost group and 6.4 (3.2) mm Hg for the dorzolamide/timolol group. Mean IOP values were similar at all time points except at 5:00 pm, when levels were significantly lower in latanoprost-treated patients (P = 0.025). After the water-drinking test, the increase in IOP values was similar between groups at baseline but lower in latanoprost-treated patients at week 8 (adjusted difference, 1.08 mm Hg

  20. Measurement of rabbit intraocular pressure with the Tono-Pen.

    Science.gov (United States)

    Mermoud, A; Baerveldt, G; Minckler, D S; Lee, M B; Rao, N A

    1995-01-01

    A Tono-Pen-1 (TP-1) and a Tono-Pen-2 (TP-2) were calibrated against direct manometry in the eyes of living rabbits to determine the accuracy of the Tono-Pen. Eighteen normal eyes of 10 rabbits were cannulated and connected to a pressure transducer with a chart recorder. Intraocular pressure (IOP) was increased from 5 to 40 mm Hg in 5-mm-Hg increments and from 40 to 80 mm Hg in 10-mm-Hg increments. After each incremental increase, IOP was measured first with a TP-1 and then with a TP-2. Plotting the mean Tono-Pen readings for each eye against the transducer pressure produced the following two regression line formulas: y = -0.613+0.790x (r2 = 0.97) for TP-1, and y = -1.45+0.824x (r2 = 0.97) for TP-2. Neither regression line was statistically different; p = 0.2 for the two slopes, and p = 0.24 for the y-axis intersection. The TP-1 and TP-2 can be used to rapidly and accurately measure the IOP in normal rabbit eyes. Tono-Pen readings do, however, significantly underestimate pressures in the range of 5-80 mm Hg. A table with 95% confidence intervals for corrected IOP readings obtained with the TP-1 or -2 is provided.

  1. Intraocular Inflammation Associated with Ocular Toxoplasmosis : Relationships at Initial Examination

    NARCIS (Netherlands)

    Dodds, Emilio M.; Holland, Gary N.; Stanford, Miles R.; Yu, Fei; Siu, Willie O.; Shah, Kayur H.; Loon, Ninette Ten Dam-Van; Muccioli, Cristina; Hovakimyan, Anna; Barisani-Asenbauer, Talin

    2008-01-01

    PURPOSE: To describe characteristics of intraocular inflammation in eyes with active ocular toxoplasmosis and to identify relationships between signs of inflammation, complications (including elevated intraocular pressure [IOP]), other disease features, and host characteristics. DESIGN: Multicenter,

  2. The Effect of Aerobic Exercise on Intraocular Pressure in Horse

    Directory of Open Access Journals (Sweden)

    Elisabetta Giudice

    2010-01-01

    Full Text Available The present study was planned to investigate the effect of the intensity of exercise on intraocular pressure (IOP, systolic and diastolic blood pressure, glycaemia and blood lactate concentration in regularly trained Italian saddle jumper horses. On the first day five female horses performed 1 h of walking on an electronically controlled horse-walker at 100 m/min; on the second day 1 h session consisted of 5 min of walk, 30 min of trot, 20 min of gallop and one exercise of a 300 m long trail with eight jumps 90 cm high to be run in 1 min. The studied indicators were collected at rest, immediately after the exercise and 30 min after the exercise. Analysis of variance (ANOVA showed a significant effect of different workloads on blood lactate concentration, systolic and diastolic blood pressure. No significant difference was found in IOP reduction when comparing aerobic and moderate anaerobic exercise. Our results confirm that the lack of a significant change in IOP in the athletic horse after mild exercise is in accordance with the human athlete. The cardiovascular and haematological changes induced by aerobic and moderate anaerobic exercise had no significant effect on IOP, either.

  3. Ocular Onchocerciasis in the Yanomami Communities from Brazilian Amazon: Effects on Intraocular Pressure

    Science.gov (United States)

    Herzog-Neto, Guilherme; Jaegger, Karen; do Nascimento, Erika S.; Marchon-Silva, Verônica; Banic, Dalma M.; Maia-Herzog, Marilza

    2014-01-01

    To determine the influence of onchocercal eye disease on the intraocular pressure of the Yanomami Tribe Aratha-ú of Roraima State, Brazil, considered endemic for onchocerciasis, a total of 86 patients were submitted to an ophthalmologic exam that included external examination, slit lamp examination, intraocular pressure measurement, and a fundus ophthalmoscope examination. A high prevalence of onchocerciasis-related eye lesions was encountered in 68.6% of the patients. Punctate keratitis and microfilariae in the anterior chamber were found in ∼28%. The mean of intraocular eye pressure found was 10.47 mm of Hg. PMID:24297812

  4. Correlation of the intraocular pressure with increased intracranial pressure in rabbits

    Directory of Open Access Journals (Sweden)

    Eskandari H

    2000-08-01

    Full Text Available Although measurement of intracranial pressure by noninvasive methods has been suggested, but mainly invasive methods are used for this purpose-Increase in episcleral venous pressure can be expected to result in a linear increase in intraocular pressure. Congested oculat veins with capillary leakage and hemorrhage are seen when the ICP is increased, thus theoretically measurement of intraocular pressure can be a procedure for estimation of the ICP. This study was performed to find whether there is andy relationship between intraocular pressure and ICP, so we used 12 albino rabbits in two divided groups. Our study was not designed to elucidate the mechanism of change but merely to record any changes observed. All measures except an increase in ICP were applied on the test group as well as on the control group. After general anesthesia with the combination of ketamin, rampune, and pentobarbital a burr hole was made in the lambda region of the skull and a cannula was placed in the subdural space. The ICP in the test group increased up to 15 mmHg and was constant throughout the experiment. Intraocular pressure was measured by Schiotz tonometers afte general anesthesia, after cannulation of the skull, and immediately after increasing the ICP which was repated in 15 minutes interval for 4 hours. There was no statistical difference between the two groups (P:0.997 . results show that neither cannulation nor general anesthesia for 4 hours produce alteration in IOP in the control group nor increasing of the ICP to level of 15 mmHg produces any alteration in IOP on the test group.

  5. Intraocular pressure variations during zygomatic fracture reduction and fixation: a clinical study.

    LENUS (Irish Health Repository)

    Murray, Dylan J

    2012-02-03

    BACKGROUND: The reduction of midface fractures has been associated with the rare but devastating complication of blindness. An increase in intraocular pressure is important in the mechanism of blindness in this setting. In this study, the authors assessed the intraocular pressure in patients who underwent zygomatic fracture reduction (with or without fixation). METHODS: Using applanation tonometry, 29 patients underwent intraocular pressure measurements before, during, and after fracture fixation. The contralateral pressures were measured and used as the control. RESULTS: There were 29 patients with a mean age of 35 years, and the mean time to surgery was 5 days. Preoperatively, all patients had normal intraocular pressures and normal visual acuity. All patients underwent a Gillies lift and 18 patients required open reduction and fixation of the frontozygomatic suture (n = 4) or the infraorbital margin (n = 2), and the remainder (n = 12) required fixation of both points. There was no statistically significant increase in the intraocular pressures following the reduction of uncomplicated zygomatic fractures. Statistically significant pressure reductions were noted immediately after reduction and fixation. CONCLUSIONS: The surgical reduction of uncomplicated zygomatic fractures has no adverse effect on the intraocular pressure. It is the authors\\' opinion that adjunctive measures to reduce the pressures are unnecessary.

  6. African Ancestry Is Associated with Higher Intraocular Pressure in Latinos.

    Science.gov (United States)

    Nannini, Drew; Torres, Mina; Chen, Yii-Der I; Taylor, Kent D; Rotter, Jerome I; Varma, Rohit; Gao, Xiaoyi

    2016-01-01

    Intraocular pressure (IOP) is a major risk factor, as well as the only modifiable risk factor, for glaucoma. Racial differences have been observed in IOP measurements with individuals of African descent experiencing the highest IOP when compared with other ethnic groups. The purpose of this study was to examine the relationship between genetic ancestry and IOP in Latinos. Population-based genetic association study. A total of 3541 participants recruited from the Los Angeles Latino Eye Study. Study participants were genotyped using the Illumina OmniExpress BeadChip (∼730K markers). We used STRUCTURE to estimate individual genetic ancestry. Simple and multiple linear regression, as well as quantile regression, analyses were performed to investigate the relationship between genetic ancestry and IOP. The relationship between genetic ancestry and IOP in Latinos. African ancestry was significantly associated with higher IOP in Latinos in our simple linear regression analysis (P = 0.002). After adjusting for age, gender, body mass index, systolic blood pressure, central corneal thickness, and type 2 diabetes, this association remained significant (P = 0.0005). The main association was modified by a significant interaction between African ancestry and hypertension (P = 0.037), with hypertensive individuals experiencing a greater increase in IOP with increasing African ancestry. To our knowledge, we demonstrate for the first time that African ancestry and its interaction with hypertension are associated with higher IOP in Latinos. Copyright © 2016 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

  7. Intraocular pressure measurement with the Tono-Pen through soft contact lenses.

    Science.gov (United States)

    Panek, W C; Boothe, W A; Lee, D A; Zemplenyi, E; Pettit, T H

    1990-01-15

    We evaluated a miniaturized digital and electronic tonometer, the Tono-Pen, for accuracy of intraocular pressure measurement in the presence of a contact lens. In the manometric study, the Tono-Pen was used to measure a known intraocular pressure, ranging from 10 mm Hg to 60 mm Hg in a cadaver eye over soft contact lenses with different powers and a plano-T bandage lens. There was significant bias in pressure measurement over all contact lenses except for the plano-T, which had no bias at any level. In the clinical study, the intraocular pressures of 40 eyes in 20 normal patients were measured with and without a plano-T contact lens in place. Analysis of variance showed no significant interactive effect between the right and left eyes, with or without the lens. There was no significant difference in the Tono-Pen measurement of intraocular pressure over a plano-T contact lens compared with no lens.

  8. Reliable intraocular pressure measurement using automated radio-wave telemetry

    Directory of Open Access Journals (Sweden)

    Paschalis EI

    2014-01-01

    Full Text Available Eleftherios I Paschalis,* Fabiano Cade,* Samir Melki, Louis R Pasquale, Claes H Dohlman, Joseph B CiolinoMassachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA, USA*These authors contributed equally to this workPurpose: To present an autonomous intraocular pressure (IOP measurement technique using a wireless implantable transducer (WIT and a motion sensor.Methods: The WIT optical aid was implanted within the ciliary sulcus of a normotensive rabbit eye after extracapsular clear lens extraction. An autonomous wireless data system (AWDS comprising of a WIT and an external antenna aided by a motion sensor provided continuous IOP readings. The sensitivity of the technique was determined by the ability to detect IOP changes resulting from the administration of latanoprost 0.005% or dorzolamide 2%, while the reliability was determined by the agreement between baseline and vehicle (saline IOP.Results: On average, 12 diurnal and 205 nocturnal IOP measurements were performed with latanoprost, and 26 diurnal and 205 nocturnal measurements with dorzolamide. No difference was found between mean baseline IOP (13.08±2.2 mmHg and mean vehicle IOP (13.27±2.1 mmHg (P=0.45, suggesting good measurement reliability. Both antiglaucoma medications caused significant IOP reduction compared to baseline; latanoprost reduced mean IOP by 10% (1.3±3.54 mmHg; P<0.001, and dorzolamide by 5% (0.62±2.22 mmHg; P<0.001. Use of latanoprost resulted in an overall twofold higher IOP reduction compared to dorzolamide (P<0.001. Repeatability was ±1.8 mmHg, assessed by the variability of consecutive IOP measurements performed in a short period of time (≤1 minute, during which the IOP is not expected to change.Conclusion: IOP measurements in conscious rabbits obtained without the need for human interactions using the AWDS are feasible and provide reproducible results.Keywords: IOP, pressure transducer, wireless, MEMS, implant, intraocular

  9. Iris color and intraocular pressure: the Blue Mountains Eye Study.

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    Mitchell, Robert; Rochtchina, Elena; Lee, Anne; Wang, Jie Jin; Mitchell, Paul

    2003-03-01

    To assess the relationship between iris color and intraocular pressure (IOP). Population-based, cross-sectional study. The Blue Mountains Eye Study examined 3,654 largely Caucasian participants, aged 49 to 97 years, from 1992 to 1994. Information was collected about glaucoma risk factors, and Goldmann applanation IOP measurements were taken. Iris color was assessed by comparing the undilated appearance of each eye with three standard photographs. Participants who had previous cataract or glaucoma surgery and those using glaucoma medications were excluded. Mean IOP measurements increased with increasing grades of iris pigmentation. After simultaneous adjustment for variables associated with IOP, mean measurements were 15.92 mm Hg for blue iris color, 16.04 mm Hg for hazel or green, 16.11 mm Hg for tan-brown, and 16.49 mm Hg for dark brown (P for trend = .001). This study demonstrates a modest but statistically significant association between increasing iris color and IOP. Copyright 2003 by Elsevier Science Inc.

  10. Aerobic exercise and intraocular pressure in normotensive and glaucoma patients

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    Chatzibalis Theodosios

    2009-08-01

    Full Text Available Abstract Background With the increasing number of people participating in physical aerobic exercise, jogging in particular, we considered that it would be worth knowing if there are should be limits to the exercise with regard to the intraocular pressure (IOP of the eyes. The purpose of this study is to check IOP in healthy and primary glaucoma patients after aerobic exercise. Methods 145 individuals were subdivided into seven groups: normotensives who exercised regularly (Group A; normotensives in whose right eye (RE timolol maleate 0.5% (Group B, latanoprost 0.005% (Group C, or brimonidine tartrate 0.2% (Group D was instilled; and primary glaucoma patients under monotherapy with β-blockers (Group E, prostaglandin analogues (Group F or combined antiglaucoma treatment (Group G instilled in both eyes. The IOP of both eyes was measured before and after exercise. Results A statistically significant decrease was found in IOP during jogging. The aerobic exercise reduces the IOP in those eyes where a b-blocker, a prostaglandin analogue or an α-agonist was previously instilled. The IOP is also decreased in glaucoma patients who are already under antiglaucoma treatment. Conclusion There is no ocular restriction for simple glaucoma patients in performing aerobic physical activity.

  11. Enalaprilat and enalapril maleate eyedrops lower intraocular pressure in rabbits.

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    Loftsson, Thorsteinn; Thorisdóttir, Sigridur; Fridriksdóttir, Hafrun; Stefánsson, Einar

    2010-05-01

    This study aimed to develop low-viscosity aqueous eyedrops containing enalaprilat and its prodrug enalapril maleate in solution, and to evaluate the eyedrops in rabbits. Aqueous eyedrops with hydroxypropyl-beta-cyclodextrin containing 0.01-2.9% (w/v) enalaprilat, 1.0% (w/v) enalapril maleate with cyclodextrin or 0.5% (w/v) timolol were prepared. The eyedrops were administered to rabbits and intraocular pressure (IOP) was measured at various time intervals after the administration and the results (mean of 10 experiments +/- standard error of the mean) are expressed as the change from baseline (24.7 +/- 3.3 mmHg). Enalaprilat possessed sufficient stability to be formulated as an aqueous eyedrop solution with a shelf-life of several years at room temperature. The maximum decline in IOP after topical administration of one drop of 2.9% enalaprilat solution was 6.2 +/- 0.7 mmHg at 4 hours after administration. Duration of activity exceeded 10 hours. A 1% enalaprilat solution lowered IOP by 4.4 +/- 0.8 mmHg at 4 hours after administration and had similar duration, and was more potent than 0.5% timolol. The enalapril maleate eyedrops resulted in delayed action, showing maximum potency at 10-22 hours after administration and duration of up to 32 hours. Enalaprilat eyedrops lower IOP in rabbits. The decline in IOP is proportional to the concentration of dissolved enalaprilat in low-viscosity aqueous eyedrop formulations.

  12. Beta2 adrenergic receptor silencing change intraocular pressure in New Zealand rabbits

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    Patricia Loma

    2018-04-01

    Full Text Available Purpose/aim: Glaucoma consists of a group of progressive optic neuropathies that are characterized by degeneration of the optic nerve and irreversible visual filed loss. Elevated intraocular pressure is the only proven treatable risk factor and commercial products used for glaucoma treatment are focused in lowering intraocular pressure. These drugs can have various undesirable side effects and this invites to look for new strategies. The purpose of this work is to study the use of a siRNA (small interfering RNA to selectively silence beta2 adrenergic receptors and to see whether it reduces IOP (intraocular pressure. Material and methods: Topical instillation of beta2 adrenergic receptors small-interfering RNA (siRNA, 25–250 μg was applied and IOP was measured with a Tonopen XL up to 9 consecutive days. The effect of such siRNA was compared to commercial compounds such as Timoftlol, Trusopt and Xalatan, and it was also analyzed if some anatomical changes occurred by microscopy. Results: siRNA designed for beta2 adrenergic receptor induced a reduction of intraocular pressure (IOP of 30 ± 5%, compared to a control (scrambled siRNA. The results in terms of IOP decrease were similar to that found with commercial compounds but a long-lasting hypotensive action was shown by beta2 adrenergic receptor siRNA treatment as compared to commercial drugs. No apparent side effects were observed in the ocular structures. Conclusion: The use of siRNA against the beta2 adrenergic receptors could provide an interesting therapeutic strategy for glaucoma treatment. Resumen: Objetivo: El glaucoma consiste en un grupo de neuropatías ópticas progresivas caracterizadas por degeneración del nervio óptico y pérdida irreversible del campo visual. La elevación de la presión intraocular es el único factor de riesgo tratable probado, centrándose los productos comerciales para el tratamiento del glaucoma en la reducción de la presión intraocular. Estos f

  13. Correlating intraocular pressure, blood pressure, and heart rate changes after jogging.

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    Karabatakis, V E; Natsis, K I; Chatzibalis, T E; Lake, S L; Bisbas, I T; Kallinderis, K A; Stangos, N T

    2004-01-01

    To examine the effects of jogging on intraocular pressure (IOP), blood pressure (BP), and heart rate (HR). Twenty-nine healthy individuals-25 athletes and 4 untrained-were studied. IOP, systolic and diastolic BP, and HR were measured before and just after 20 minutes of jogging (submaximal--70%--aerobic exercise). IOP decreased after jogging. Only three individuals had unchanged IOP in one eye and one individual in both eyes. The IOP decrease (1 to 8 mmHg) was statistically significant (pjogging (systolic: 0 to 60 mmHg, statistically significant changes, pjogging. Changes in BP and HR values have no linear quantitative correlation with IOP decrease.

  14. Evaluation of the diurnal intraocular pressure fluctuations and blood pressure under dehydration due to fasting

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    Gonen Baser

    2016-12-01

    Full Text Available Introduction: This study aimed to investigate the diurnal intraocular pressure fluctuations under dehydration conditions and the relationship between the intraocular pressure fluctuations and blood pressure. Methods: The intraocular pressures (IOP, body weights, as well as systolic and diastolic blood pressures (SBP, DBP of 36 fasting healthy volunteers were recorded at 8:00 a.m. and 5:00 p.m. in the Ramadan of 2014 and two weeks after it. The data were analyzed using paired Student’s t-test and Pearson correlation analysis. Results: As the results demonstrated, the mean diurnal IOP differences of IOP, SBP, DBP, and weight were 2.67±1.33 mmHg, 9.44±8.02 mmHg, 3.33±5.94 mmHg, and 0.90±0.46 kg during the fasting period, respectively. In addition, the mean diurnal IOP differences of IOP, SBP, DBP, and weight were -0.33±1.4 mmHg (P=0.001, 0.55±7.25mmHg (P=0.003, -3.33±5.94 mmHg (P=0.001, and 0.12±0.45 kg (P=0.001 during the control period, respectively. There was a moderate correlation between the diurnal IOP and SBP differences (r=0.517, P=0.028. Conclusion: Based on the findings of the current study, the total fluid volume might have a more dominant effect on IOP peaks than the sympathetic system activity. Furthermore, the SBP was found to correlate with the IOP.

  15. Lens parameters as predictors of intraocular pressure changes after phacoemulsification.

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    Moghimi, S; Abdi, F; Latifi, G; Fakhraie, G; Ramezani, F; He, M; Lin, S C

    2015-11-01

    To evaluate intraocular pressure (IOP) change after cataract surgery in non-glaucomatous eyes with narrow and open angles (OAs) and its relation to novel lens parameters measured by anterior segment optical coherence tomography (AS-OCT). University affiliated hospital, Farabi Eye Hospital, Tehran, Iran. Prospective interventional case series. In this prospective study, 85 non-glaucomatous eyes underwent phacoemulsification and lens implantation. Thirty-nine eyes had OAs and 46 eyes had narrow angles (NAs). IOP and biometric parameters were measured by AS-OCT preoperatively and 3 months after surgery. Change in IOP and its relation to biometric parameters, including lens vault (LV), anterior vault (AV), defined as the sum of the LV and the ACD, and relative LV (rLV), defined as the ratio of the LV to the AV, were evaluated. The main outcome measure was degree of IOP change after phacoemulsification. Of the 85 patients included in the analysis, 35 were male and 50 were female with an overall mean age of 62.2 ± 8.9 years. The average IOP reduction was -4.95 ± 2.26 mm Hg, from a preoperative mean of 17.12 ± 2.47 mm Hg, at 3 months after cataract surgery. The amount of IOP reduction was significantly greater in the NA compared with the OA group. In multivariate linear regression analysis, preoperative IOP and AV were significantly associated with IOP decrease (all ≤ 0.03). Cataract surgery results in IOP reduction in both OA and NA eyes. The amount of IOP reduction is related to AV.

  16. Risk factors for intraocular pressure rise following phacoemulsification

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    Muge Coban-Karatas

    2013-01-01

    Full Text Available Purpose: This study was designed to analyze the risk factors resulting in high intraocular pressure (IOP, which was accepted as IOP higher than 22 mmHg, following uncomplicated phacoemulsification. Materials and Methods: The records of 812 eyes of 584 patients who underwent uncomplicated phacoemulsification were evaluated. There were 330 men and 254 women ranging between the age of 26 and 89 years (65.4 ± 9.8 years. The preoperative, postoperative first day (day 1, first week (day 7, and first month (day 30 IOP values were analyzed. Data on history of diabetes, glaucoma, pseudoexfoliation (PXF, incision site, capsular staining with trypan blue, and surgeon were recorded. A multinomial regression analysis was performed to analyse the relationship of the factors with postoperative high IOP. Results: The mean IOP was 15.6 ± 4.3 mmHg preoperatively. Postoperatively that were changed to 19.7 ± 9.0 mmHg at day 1, 12.7 ± 4.5 mmHg at day 7, and 12.8 ± 3.7 mmHg at day 30. The factors such as surgeon, presence of PXF, diabetes, surgical incision site, and trypan blue were not related to the postoperative high IOP (P > 0.05, in all. The only factor that related to high IOP at all visits was glaucoma (P < 0.005. Conclusion: According to our results, preoperative diagnosis of glaucoma seems to be the only factor to affect the postoperative IOP higher than 22 mmHg.

  17. Effect of Hydrogen Sulfide Donors on Intraocular Pressure in Rabbits.

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    Salvi, Ankita; Bankhele, Pratik; Jamil, Jamal; Chitnis, Madhura Kulkarni; Njie-Mbye, Ya Fatou; Ohia, Sunny E; Opere, Catherine A

    2016-01-01

    In this study, we investigated the effect of a slow-releasing hydrogen sulfide (H2S) donor, GYY 4137, on intraocular pressure (IOP) in normotensive rabbits. Furthermore, we compared the IOP-lowering action of GYY 4137 with those elicited by other H2S-producing compounds, l-cysteine and ACS67 (a hybrid compound of latanoprost with an H2S-releasing moiety). IOP was measured in New Zealand normotensive male albino rabbits using a pneumatonometer (model 30 classic; Reichert Ophthalmic Instruments, Depew, NY). At 0 h, 50 μL of test compounds were applied topically to 1 eye of each animal, while the contralateral eye received the same quantity of vehicle (saline). IOP was measured hourly until baseline IOP readings were attained and animal eyes monitored for potential side effects (i.e., tearing, hyperemia). GYY 4137 (0.1%-2%) produced a dose-dependent decrease in IOP reaching a maximum of 27.8% ± 3.14% (n = 5) after 6 h. Interestingly, a significant contralateral effect was observed in vehicle-treated controls eyes at all doses tested. l-cysteine (5%) and ACS67 (0.005%) also elicited a significant (P vehicle-treated control eyes. We conclude that GYY 4137 and other H2S-producing donors can reduce IOP in normotensive rabbits. However, the profile of IOP-lowering action of GYY 4137 was different from the other H2S donors affirming its ability to act as a slow-releasing gas donor.

  18. Driving time modulates accommodative response and intraocular pressure.

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    Vera, Jesús; Diaz-Piedra, Carolina; Jiménez, Raimundo; Morales, José M; Catena, Andrés; Cardenas, David; Di Stasi, Leandro L

    2016-10-01

    Driving is a task mainly reliant on the visual system. Most of the time, while driving, our eyes are constantly focusing and refocusing between the road and the dashboard or near and far traffic. Thus, prolonged driving time should produce visual fatigue. Here, for the first time, we investigated the effects of driving time, a common inducer of driver fatigue, on two ocular parameters: the accommodative response (AR) and the intraocular pressure (IOP). A pre/post-test design has been used to assess the impact of driving time on both indices. Twelve participants (out of 17 recruited) completed the study (5 women, 24.42±2.84years old). The participants were healthy and active drivers with no visual impairment or pathology. They drove for 2h in a virtual driving environment. We assessed AR and IOP before and after the driving session, and also collected subjective measures of arousal and fatigue. We found that IOP and AR decreased (i.e., the accommodative lag increased) after the driving session (p=0.03 and p<0.001, respectively). Moreover, the nearest distances tested (20cm, 25cm, and 33cm) induced the highest decreases in AR (corrected p-values<0.05). Consistent with these findings, the subjective levels of arousal decreased and levels of fatigue increased after the driving session (all p-values<0.001). These results represent an innovative step towards an objective, valid, and reliable assessment of fatigue-impaired driving based on visual fatigue signs. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Acute effects of consumption of energy drinks on intraocular pressure and blood pressure

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    Ilechie AA

    2011-04-01

    Full Text Available A Alex Ilechie, Sandra TettehDepartment of Optometry, University of Cape Coast, GhanaBackground: Energy drinks contain a wide variety of ingredients including caffeine, for which there have been conflicting reports regarding its effects on intraocular pressure (IOP and blood pressure. The aim of this study was to investigate the acute effects of an energy drink (Red Bull® on the IOP and blood pressure of healthy young adults.Methods: Thirty healthy university students of either gender, aged 18–30 (mean 23.20 ± 2.81 years were randomly selected to participate in this study. The subjects were randomly divided into two groups (experimental and control and were asked to abstain from caffeine for 48 hours prior to and during the study. Baseline IOP and blood pressure were measured. The experimental group (n = 15 consumed one can of the energy drink (containing 85 mg of caffeine in 250 mL and measurements were repeated at 30, 60, and 90 minutes, while the control group drank 250 mL of water and were tested over the same time period.Results: When compared with baseline, a significant decrease (P < 0.05 in mean IOP at 60 and 90 minutes was observed in the experimental group. There was no corresponding change in systolic or diastolic blood pressure.Conclusion: Our results suggest that energy drinks (ie, Red Bull produce a significant reduction in IOP but have no effect on blood pressure. These findings may be interpreted as reflecting the effect of the combination of caffeine and taurine in the Red Bull energy drink. This effect may result from the known hypotensive effect of taurine, and warrants further study.Keywords: acute effect, intraocular pressure, blood pressure, glaucoma, caffeine, taurine

  20. The impact of ocular hemodynamics and intracranial pressure on intraocular pressure during acute gravitational changes.

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    Nelson, Emily S; Mulugeta, Lealem; Feola, Andrew; Raykin, Julia; Myers, Jerry G; Samuels, Brian C; Ethier, C Ross

    2017-08-01

    Exposure to microgravity causes a bulk fluid shift toward the head, with concomitant changes in blood volume/pressure, and intraocular pressure (IOP). These and other factors, such as intracranial pressure (ICP) changes, are suspected to be involved in the degradation of visual function and ocular anatomical changes exhibited by some astronauts. This is a significant health concern. Here, we describe a lumped-parameter numerical model to simulate volume/pressure alterations in the eye during gravitational changes. The model includes the effects of blood and aqueous humor dynamics, ICP, and IOP-dependent ocular compliance. It is formulated as a series of coupled differential equations and was validated against four existing data sets on parabolic flight, body inversion, and head-down tilt (HDT). The model accurately predicted acute IOP changes in parabolic flight and HDT, and was satisfactory for the more extreme case of inversion. The short-term response to the changing gravitational field was dominated by ocular blood pressures and compliance, while longer-term responses were more dependent on aqueous humor dynamics. ICP had a negligible effect on acute IOP changes. This relatively simple numerical model shows promising predictive capability. To extend the model to more chronic conditions, additional data on longer-term autoregulation of blood and aqueous humor dynamics are needed. NEW & NOTEWORTHY A significant percentage of astronauts present anatomical changes in the posterior eye tissues after spaceflight. Hypothesized increases in ocular blood volume and intracranial pressure (ICP) in space have been considered to be likely factors. In this work, we provide a novel numerical model of the eye that incorporates ocular hemodynamics, gravitational forces, and ICP changes. We find that changes in ocular hemodynamics govern the response of intraocular pressure during acute gravitational change. Copyright © 2017 the American Physiological Society.

  1. Intraocular pressure 1 year after vitrectomy in eyes without a history of glaucoma or ocular hypertension

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    Fang Y

    2017-11-01

    Full Text Available Yuan Fang,1 Qingqing Long,1 Xiaoqian Wang,2 Rui Jiang,1 Xinghuai Sun1,3–5 1Department of Ophthalmology and Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, 2Department of Ophthalmology, Jiangyin Bright Eye Hospital, Jiangyin, Jiangsu, 3State Key Laboratory of Medical Neurobiology, Institutes of Brain Science and Collaborative Innovation Center for Brain Science, 4Key Laboratory of Myopia, NHFPC (Fudan University, 5Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, People’s Republic of China Objective: The aim of this study was to investigate the incidence, risk factors, and treatment of elevated intraocular pressure (IOP 1 year after vitrectomy in eyes without a history of glaucoma or ocular hypertension.Patients and methods: This retrospective study comprised 256 eyes from 256 consecutive patients without a history of glaucoma or ocular hypertension who underwent vitrectomy and were followed up for 1 year. The incidence of elevated IOP at 1 year after vitrectomy was calculated. We compared the characteristics of patients with or without elevated IOP to identify possible risk factors for elevated IOP. The treatments used to control IOP were recorded and analyzed.Results: A total of 50 patients (19.5% had elevated IOP after vitrectomy at the 1-year follow-up. Tamponade was a significant risk factor for elevated IOP (P<0.05. The cumulative rates of elevated IOP in eyes with air, balanced salt solution, sulfur hexafluoride, perfluoropropane (C3F8, and silicone oil as the tamponade were 0, 10.8%, 5.9%, 19.8%, and 28.4%, respectively (P<0.05. About 68% of cases of elevated IOP occurred within 1 month after vitrectomy. At 1 year after vitrectomy, 29 patients (58.0% had stopped their IOP-lowering drugs and 21 (42.0% patients were continuing these drugs. About 65% of ocular hypertension patients who received silicone oil tamponade had not stopped IOP-lowering drugs

  2. Reference intervals for intraocular pressure measured by rebound tonometry in ten raptor species and factors affecting the intraocular pressure.

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    Reuter, Anne; Müller, Kerstin; Arndt, Gisela; Eule, Johanna Corinna

    2011-09-01

    Intraocular pressure (IOP) was measured with the TonoVet rebound tonometer in 10 raptor species, and possible factors affecting IOP were investigated. A complete ophthalmic examination was performed, and IOP was assessed in 2 positions, upright and dorsal recumbency, in 237 birds belonging to the families Accipitridae, Falconidae, Strigidae, and Tytonidae. Mean IOP values of healthy eyes were calculated for each species, and differences between families, species, age, sex, left and right eye, as well as the 2 body positions were evaluated. Physiologic fluctuations of IOP were assessed by measuring IOP serially for 5 days at the same time of day in 15 birds of 3 species. Results showed IOP values varied by family and species, with the following mean IOP values (mm Hg +/- SD) determined: white-tailed sea eagle (Haliaeetus albicilla), 26.9 +/- 5.8; red kite (Milvus milvus), 13.0 +/- 5.5; northern goshawk (Accipiter gentilis), 18.3 +/- 3.8; Eurasian sparrowhawk (Accipiter nisus), 15.5 +/- 2.5; common buzzard (Buteo buteo), 26.9 +/- 7.0; common kestrel (Falco tinnunculus), 9.8 +/- 2.5; peregrine falcon, (Falco peregrinus), 12.7 +/- 5.8; tawny owl (Strix aluco), 9.4 +/- 4.1; long-eared owl (Asio otus), 7.8 +/- 3.2; and barn owl (Tyto alba), 10.8 +/- 3.8. No significant differences were found between sexes or between left and right eyes. In goshawks, common buzzards, and common kestrels, mean IOP was significantly lower in juvenile birds than it was in adult birds. Mean IOP differed significantly by body position in tawny owls (P = .01) and common buzzards (P = .04). By measuring IOP over several days, mean physiologic variations of +/- 2 mm Hg were detected. Differences in IOP between species and age groups should be considered when interpreting tonometric results. Physiologic fluctuations of IOP may occur and should not be misinterpreted. These results show that rebound tonometry is a useful diagnostic tool in measuring IOP in birds of prey because it provides rapid

  3. [Association between two different types of strangling and intraocular pressure variation in jiu-jitsu athletes].

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    Scarpi, Marinho Jorge; Conte, Marcelo; Rossin, Reginaldo Alexandre; Skubs, Renato; Lenk, Rudolf Eberhard; Brant, Rodrigo

    2009-01-01

    To verify the association between two different types of strangling with intraocular pressure variation in jiu-jitsu athletes. An observational study was performed on 9 athletes of jiu-jitsu, with at least 6 month of training, male, aged 20 to 30 years, without any physical and eyeball lesions. Associations between intraocular pressure and Cross Choke from the guard strangling (E1), and E2 - Cross Choke from mount strangling were gotten. Intraocular pressure was determined by using Perkins tonometer, at first in the absence of physical exercise over the last 24 hours and after each strangling. Then it was carried out the intraocular pressure measure at each 3 minutes, during 12 minutes of exercise recovery (R1, R2, R3, and R4) keeping the athletes lied down. Statistical analysis was done using ANOVA test and Bonferroni post-test. Meaningful reduction of both eyes intraocular pressure occurred at the E2 situation comparing to the E1 situation at all exercise recovery measures: R1 (OD: 8.22 +/- 1.39 vs.11.33 +/- 2.00 / OE: 8.55 +/- 1.23 vs. 11.88 +/- 1.90), R2 (OD: 8.44 +/- 1.87 vs.10.22 +/- 2.53 / OE: 9.00 +/- 1.80 vs. 10.44 +/- 2.35), R3 (OD: 8.44 +/- 1.74 vs.9.78 +/- 2.54 / OE: 8.55 +/- 1.42 vs. 10.33 +/- 1.93) all with pjiu-jitsu strangling exercises, with intraocular pressure reduction.

  4. CORRELATION OF OCULAR PERFUSION PRESSURE AND INTRAOCULAR PRESSURE CHANGES DURING HAEMODIALYSIS IN END STAGE RENAL DISEASE- AN OBSERVATIONAL STUDY

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    T. R. Anuradha

    2017-12-01

    Full Text Available BACKGROUND Chronic kidney disease patients on haemodialysis have a transient raise in intraocular pressure and decrease in ocular perfusion pressure. This is used in early detection of glaucomatous optic nerve damage and subsequent irreversible visual loss. MATERIALS AND METHODS 100 chronic kidney disease patients under haemodialysis in the nephrology department, Stanley medical college for more than one month were included in the study. We recorded complete history, and all participants were subjected to Intraocular pressure and blood pressure measurement at 3 different timings during haemodialysis session. Mean Arterial Pressure (MAP, Ocular Perfusion Pressure (OPP, Systolic Ocular Perfusion Pressure (SOPP, Diastolic Ocular Perfusion Pressure (DOPP and Mean Ocular Perfusion Pressure (MOPP were calculated. RESULTS Mean IOP from the initiation to the end of haemodialysis was found to be increased. Mean arterial pressure, ocular perfusion pressure, systolic ocular perfusion pressure, diastolic ocular perfusion pressure, mean ocular perfusion pressure was found to be decreased from the initiation to the end of haemodialysis. At the end of study period, 10% were found to develop early glaucomatous field defects and early optic nerve head changes in both eyes at follow-up. CONCLUSION Our study reveals the importance of screening and monitoring of intraocular pressure and characteristic early optic nerve head changes and early visual field changes of glaucoma in end-stage renal disease patients who are on haemodialysis.

  5. Effect of oxymetazoline nasal spray on intraocular pressure and retrobulbar hemodynamics.

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    Arikan, Osman Kursat; Akarsu, Cengiz; Unal, Birsen; Ergin, Ahmet; Koç, Can

    2006-02-01

    To determine the effect of oxymetazoline nasal spray on intraocular pressure and retrobulbar hemodynamics in patients with open-angle glaucoma and to compare the results with those measured in healthy control participants. Controlled, prospective clinical trial. University hospital. Thirty patients with open-angle glaucoma and 30 healthy volunteers as controls were topically self-administered oxymetazoline nasal spray three times a day (one spray in each nostril of 0.05% concentration) for 5 days continuously. Intraocular pressure and retrobulbar hemodynamics were measured in glaucomatous and normal eyes at baseline and at the end of oxymetazoline application . Oxymetazoline nasal spray lowered intraocular pressure significantly in both the glaucoma group (p = .02) and the control group (p = .001) after 5 days of treatment. The systemic parameters in the glaucoma and control groups (systolic blood pressure, p = .14 and p = .17; diastolic blood pressure, p = .18 and p = .49; and pulse rate, p = .06 and p = .50, respectively) did not show statistically significant differences during the study period. Additionally, except with a significant decrease in the resistivity index of the central retinal artery in the glaucoma patients (p = .001), oxymetazoline nasal spray did not result in any significant changes in the retrobulbar hemodynamics in both the glaucoma and control groups. This study showed that a 5-day treatment with oxymetazoline nasal spray reduced intraocular pressure in both healthy controls and patients with glaucoma under treatment. In addition, it had no significant adverse effects on the retrobulbar hemodynamics.

  6. Changes of intraocular pressure in different trimesters of pregnancy among Syrian refugees in Turkey: A cross-sectional study.

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    Tolunay, Harun Egemen; Özcan, Sait Coşkun; Şükür, Yavuz Emre; Özarslan Özcan, Deniz; Adıbelli, Fatih Mehmet; Hilali, Neşe Gül

    2016-06-01

    To evaluate the physiologic changes in intraocular pressure associated with pregnancy in healthy Syrian refugee women in Turkey. In this cross-sectional study, intraocular pressures were measured using a Goldmann tonometer in 235 patients in the first, second, and third trimester of pregnancy and puerperium among Syrian refugees in Turkey. Mean intraocular pressures values of the right eye were 15.5±2.5 mmHg, 14.4±1.4 mmHg, 13.9±1.6 and 14.7±1.9 mmHg in the three trimesters and puerperium, respectively. Mean intraocular pressures values of the left eye were 15.3±1.6 mmHg, 14.3±1.4 mmHg, 13.9±1.6 and 15.3±2.2 mmHg in the three trimesters and puerperium, respectively. The mean intraocular pressures values measured from both eyes were significantly higher in first trimester and puerperal period than in the third trimester (p<0.001). Changes in the intraocular pressure in pregnancy are common and temporary. This study shows the baseline changes in the intraocular pressure during pregnancy in healthy women. Therefore, we cannot extrapolate the results to the whole eye. A decrease in intraocular pressures was shown in healthy pregnant women.

  7. Correlation between Central Corneal Thickness and Intraocular Pressure Measured by Goldmann Applanation Tonometry or Pascal Dynamic Contour Tonometry.

    Science.gov (United States)

    Katsimpris, J M; Theoulakis, P E; Vasilopoulos, K; Skourtis, G; Papadopoulos, G E; Petropoulos, I K

    2015-04-01

    The aim of this study was to investigate the relationship between central corneal thickness and intraocular pressure measured by Goldmann applanation tonometry and Pascal dynamic contour tonometry. The study included 45 persons (90 eyes), divided into 4 groups: a) 10 normal volunteers (20 eyes); b) 16 patients (32 eyes) with primary open-angle glaucoma; c) 8 patients (16 eyes) with normal-tension glaucoma; and d) 11 patients (22 eyes) with ocular hypertension. Intraocular pressure was measured by Goldmann applanation tonometry and Pascal dynamic contour tonometry, and central corneal thickness was measured by ultrasound pachymetry. The relationship between intraocular pressure and central corneal thickness was evaluated. Intraocular pressure was correlated positively but not strongly enough with central corneal thickness when it was measured by Goldmann applanation tonometry. On the contrary, there was no correlation between intraocular pressure and central corneal thickness when intraocular pressure was measured by Pascal dynamic contour tonometry. Central corneal thickness is an important variable in the evaluation of intraocular pressure by Goldmann applanation tonometry. This factor does not interfere with the intraocular pressure measurements taken by Pascal dynamic contour tonometry. Georg Thieme Verlag KG Stuttgart · New York.

  8. The role of day one postoperative review of intraocular pressure in modern vitrectomy surgery.

    Science.gov (United States)

    Brennan, Nicholas; Reekie, Ian; Ezra, Eric; Barton, Keith; Viswanathan, Ananth; Muqit, Mahiul Mk

    2017-09-01

    With the introduction of sutureless 23-gauge (23G) vitrectomy, the risks for elevated intraocular pressure (IOP) and the need for day 1 review of IOP are less certain. To assess current practice for postoperative review in the vitreoretinal service at a large tertiary referral centre; to assess whether day 1 review detected complications altering patient management; to identify risk factors for IOP spikes postvitrectomy. Retrospective, consecutive case note review of all patients undergoing 23G vitrectomy at the study institution between April and June 2013. Patients had assessment at either day 1, week 2 and month 2 or week 2 and month 2. Linear regression analysis was performed to identify risk factors for IOP elevation. 200 (89%) cases met inclusion criteria. Of these, 176 (89.3%) had day 1 review, 24 (12%) were seen at week 2. Mean follow-up was 120 days (range 20-360). Two cases (1%) required urgent surgical intervention due to early IOP complications. Combined laser was the only risk factor for a day 1 IOP spike (p=0.005). In total, 44 patients (22%) were treated for elevated IOP within 2 weeks following vitrectomy. No long-term complications were detected in these patients. Day 1 review detected adverse events in 0.5% of study patients. No long-term complications were reported in the 22% of patients who received treatment for early postoperative IOP elevation. This observation has led to the removal of routine day 1 review from the surgical care pathway following routine uncomplicated vitrectomy at the study institution. 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/.

  9. Associations with intraocular pressure across Europe: The European Eye Epidemiology (E-3) Consortium

    NARCIS (Netherlands)

    Khawaja, Anthony P.; Springelkamp, Henriët; Creuzot-Garcher, Catherine; Delcourt, Cécile; Hofman, Albert; Höhn, René; Iglesias, Adriana I.; Wolfs, Roger C. W.; Korobelnik, Jean-François; Silva, Rufino; Topouzis, Fotis; Williams, Katie M.; Bron, Alain M.; Buitendijk, Gabriëlle H. S.; Cachulo, Maria da Luz; Cougnard-Grégoire, Audrey; Dartigues, Jean-François; Hammond, Christopher J.; Pfeiffer, Norbert; Salonikiou, Angeliki; van Duijn, Cornelia M.; Vingerling, Johannes R.; Luben, Robert N.; Mirshahi, Alireza; Lamparter, Julia; Klaver, Caroline C. W.; Jansonius, Nomdo M.; Foster, Paul J.; Acar, Niyazi; Anastosopoulos, Eleftherios; Azuara-Blanco, Augusto; Bergen, Arthur; Bertelsen, Geir; Binquet, Christine; Bird, Alan; Brétillon, Lionel; Bron, Alain; Buitendijk, Gabrielle; Cachulo, Maria Luz; Chakravarthy, Usha; Chan, Michelle; Chang, Petrus; Colijn, Annemarie; Cumberland, Philippa; Cunha-Vaz, José; Daien, Vincent; Deak, Gabor; Delyfer, Marie-Noëlle; Hollander, Anneke den; Dietzel, Martha; Erke, Maja Gran; Fauser, Sascha; Finger, Robert; Fletcher, Astrid; Foster, Paul; Founti, Panayiota; Göbel, Arno; Gorgels, Theo; Grauslund, Jakob; Grus, Franz; Hammond, Christopher; Helmer, Catherine; Hense, Hans-Werner; Hermann, Manuel; Hoehn, René; Hogg, Ruth; Holz, Frank; Hoyng, Carel; Jansonius, Nomdo; Janssen, Sarah; Khawaja, Anthony; Klaver, Caroline; Le Goff, Mélanie; Leal, Sergio; Lechanteur, Yara; Lehtimäki, Terho; Lotery, Andrew; Leung, Irene; Mauschitz, Matthias; Merle, Bénédicte; Meyer Zu Westrup, Verena; Midena, Edoardo; Miotto, Stefania; Mohan-Saïd, Sadek; Muldrew, Alyson; Mueller, Michael; Nunes, Sandrina; Oexle, Konrad; Peto, Tunde; Piermarocchi, Stefano; Prokofyeva, Elena; Rahi, Jugnoo; Raitakari, Olli; Ribeiro, Luisa; Rougier, Marie-Bénédicte; Sahel, José; Salonikiou, Aggeliki; Sanchez, Clarisa; Schmitz-Valckenberg, Steffen; Schweitzer, Cédric; Segato, Tatiana; Shehata, Jasmin; Silvestri, Giuliana; Simader, Christian; Souied, Eric; Springelkamp, Henriet; Tapp, Robyn; Verhoeven, Virginie; Von Hanno, Therese; Vujosevic, Stela; Williams, Katie; Wolfram, Christian; Yip, Jennifer; Zerbib, Jennyfer; Zwiener, Isabella

    2016-01-01

    Raised intraocular pressure (IOP) is the most important risk factor for developing glaucoma, the second commonest cause of blindness globally. Understanding associations with IOP and variations in IOP between countries may teach us about mechanisms underlying glaucoma. We examined cross-sectional

  10. Baseline Intraocular Pressure Is Associated with Subjective Sensitivity to Physical Exertion in Young Males

    Science.gov (United States)

    Vera, Jesús; Jiménez, Raimundo; García, José Antonio; Perales, José Cesar; Cárdenas, David

    2018-01-01

    Purpose: The purposes of this study were to (a) investigate the effect of physical effort (cycling for 60 min at 60 ± 5% of individually computed reserve heart-rate capacity), combined with 2 different levels of cognitive demand (2-back, oddball), on intraocular pressure (IOP) and subjective judgments of perceived exertion (ratings of perceived…

  11. time effect of exercise on intraocular pressure in a Nigerian population

    African Journals Online (AJOL)

    Numerous international studies have indicated that several physiological changes can influence the intraocular pressure (IOP) of subjects. In order to assess visual health status through physiological changes, the effects of rest and exercise on IOP were investigated in a Nigerian community. The research involved 24 ...

  12. Common Genetic Determinants of Intraocular Pressure and Primary Open-Angle Glaucoma

    NARCIS (Netherlands)

    van Koolwijk, Leonieke M. E.; Ramdas, Wishal D.; Ikram, M. Kamran; Jansonius, Nomdo M.; Pasutto, Francesca; Hysi, Pirro G.; Macgregor, Stuart; Janssen, Sarah F.; Hewitt, Alex W.; Viswanathan, Ananth C.; ten Brink, Jacoline B.; Hosseini, S. Mohsen; Amin, Najaf; Despriet, Dominiek D. G.; Willemse-Assink, Jacqueline J. M.; Kramer, Rogier; Rivadeneira, Fernando; Struchalin, Maksim; Aulchenko, Yurii S.; Weisschuh, Nicole; Zenkel, Matthias; Mardin, Christian Y.; Gramer, Eugen; Welge-Luessen, Ulrich; Montgomery, Grant W.; Carbonaro, Francis; Young, Terri L.; Bellenguez, Celine; McGuffin, Peter; Foster, Paul J.; Topouzis, Fotis; Mitchell, Paul; Wang, Jie Jin; Wong, Tien Y.; Czudowska, Monika A.; Hofman, Albert; Uitterlinden, Andre G.; Wolfs, Roger C. W.; de Jong, Paulus T. V. M.; Oostra, Ben A.; Paterson, Andrew D.; Mackey, David A.; Bergen, Arthur A. B.; Reis, Andre; Hammond, Christopher J.; Vingerling, Johannes R.; Lemij, Hans G.; Klaver, Caroline C. W.; van Duijn, Cornelia M.

    2012-01-01

    Intraocular pressure (IOP) is a highly heritable risk factor for primary open-angle glaucoma and is the only target for current glaucoma therapy. The genetic factors which determine IOP are largely unknown. We performed a genome-wide association study for IOP in 11,972 participants from 4

  13. Reliability of intraocular pressure measurement with the Goldmann applanation tonometer in epidemiological studies

    NARCIS (Netherlands)

    I. Dielemans (Ida); J.R. Vingerling (Hans); A. Hofman (Albert); D.E. Grobbee (Diederick); P.T.V.M. de Jong (Paulus)

    1994-01-01

    textabstractThe reproducibility of intraocular pressure (IOP) measurement with the Goldmann applanation tonometer was investigated as part of a population-based epidemiological study. Sixty-two subjects were examined in a first measurement session. The IOP was measured three times consecutively in

  14. Early postoperative intraocular pressure stability after combined 23-gauge sutureless vitrectomy and cataract surgery in patients with proliferative diabetic retinopathy.

    Science.gov (United States)

    Lee, Jong Yeon; Jeong, Hoon Seok; Lee, Dae Yeong; Sohn, Hee Jin; Nam, Dong Heun

    2012-10-01

    To compare rates of early postoperative hypotony and intraocular pressure (IOP) elevation between 23-gauge sutureless vitrectomies with and without phacoemulsification and intraocular lens implantation in patients with proliferative diabetic retinopathy. This study reviewed the medical records of 302 eyes of patients who underwent primary 23-gauge sutureless vitrectomy for the complications of proliferative diabetic retinopathy. A case series of 207 eyes that underwent combined vitrectomy and cataract surgery (combined group) was compared with that of 95 eyes that underwent vitrectomy only (vitrectomy group): The eyes that remained phakic after the vitrectomy were excluded from this study. The main outcome measures were postoperative hypotony (IOP 30 mmHg). Postoperative hypotony was identified in 4 (1.9%) of 207 eyes in combined group, but in 7 (7.4%) of 95 eyes in vitrectomy group (P = 0.048). Rate of IOP elevation was very low and not different between the two groups. The multivariate analysis showed that vitrectomy without cataract surgery was associated with the postoperative hypotony (odds ratio = 4.6, P = 0.045). The incidence of early postoperative hypotony was lower in combined sutureless vitrectomy and cataract surgery than in sutureless vitrectomy alone and that of IOP elevation was very low in both groups. The maintenance of a stable IOP with a low risk of IOP fluctuation may be an additional advantage of sutureless diabetic vitrectomy combined with cataract surgery.

  15. Intraocular pressure-lowering effect of oral paracetamol and its in vitro corneal penetration properties

    Directory of Open Access Journals (Sweden)

    Mohamed N

    2013-01-01

    Full Text Available Nabiel Mohamed, David MeyerDivision of Ophthalmology, Faculty of Medicine and Health Sciences, University of Stellenbosch, Cape Town, South AfricaBackground: Several studies have confirmed the ability of cannabinoids to reduce intraocular pressure. Experimental data recently demonstrated unequivocally that the analgesic effect of paracetamol is due to its indirect action on cannabinoid receptors. The question then arises as to whether paracetamol can reduce intraocular pressure via its effect on intraocular cannabinoid receptors.Methods: A 2-week, prospective, randomized, controlled, single-center, parallel-group pilot study was carried out to determine the efficacy and safety of paracetamol 1 g orally administered every 6 hours in adult patients with primary or secondary open angle glaucoma as compared with topical levobunolol 0.5% twice a day. Patient well-being was closely monitored throughout the study and focused on hepatic safety in accordance with Drug-Induced Liver Injury Network criteria. The in vitro diffusion kinetics of acetaminophen in a phosphate-buffered solution in rabbit and human corneas was also investigated, with the view to a topical application.Results: Eighteen adult patients were enrolled in the study, with nine in the topical levobunolol group and nine in the oral paracetamol group. In the levobunolol group, the mean reduction in intraocular pressure at day 7 was 7.5 mmHg (P < 0.008 and at day 14 was 9.1 mmHg (P < 0.005, from a mean baseline intraocular pressure of 29.6 mmHg. The corresponding figures for the paracetamol group were 8.8 mmHg (P < 0.0004 at day 7 and 6.5 mmHg (P < 0.004 at day 14, from a mean baseline intraocular pressure of 29.4 mmHg. Both study regimens were well tolerated. No serious treatment-related adverse events were reported in either of the treatment groups. Liver function tests, systolic/diastolic blood pressure, or heart rate remained unchanged in both groups during the 2 weeks of the study. In

  16. Real-time intraocular pressure measurement during phacoemulsification in dogs ex vivo

    Science.gov (United States)

    KANG, Seonmi; PARK, Sangwan; NOH, Hyunwoo; KWAK, Jiyoon; SEO, Kangmoon

    2015-01-01

    This study was performed to evaluate changes in intraocular pressure (IOP) during standard coaxial phacoemulsification using 4 different bottle heights (BHs) and 2 different incision sizes. Coaxial phacoemulsification was performed with a venturi-based machine in 8 enucleated canine eyes through 3.0 and 3.2 mm clear corneal incisions (CCIs). A pressure transducer inserted in the peripheral cornea monitored the IOP in real-time. The surgery was subdivided into 4 stages: sculpt-segment removal, irrigation/aspiration, capsular polishing and viscoelastic removal. The mean IOP and the difference between the maximum and minimum IOPs were calculated at each stage and compared. The ultrasound time and volume of irrigation fluid used were recorded. The mean IOP increased with an elevation in the BH. The mean IOP in the irrigation/aspiration stage was significantly higher than that in the sculpt-segment removal stage at the same BH. The difference between the maximum and minimum IOP at each stage was greater in the 3.2 mm than the 3.0 mm CCIs, although the mean IOP was lower with the 3.2 mm than the 3.0 mm CCIs. The ultrasound time and irrigation fluid volume were greater with the 3.2 mm than the 3.0 mm CCIs. Therefore, fluidic parameters during each stage could be reassessed and adjusted to reduce complications arising from an elevated IOP. Phacoemulsification with 3.0 mm CCIs at a lower BH might lead to less stress on the eye from IOP fluctuations, ultrasound energy and irrigation fluid. PMID:25716691

  17. Intraocular pressure spikes after a sequential laser peripheral iridotomy for angle closure.

    Science.gov (United States)

    Lee, Tian-Loon; Yuxin Ng, Jamie; Nongpiur, Monisha E; Tan, Wai-Jia; Aung, Tin; Perera, Shamira A

    2014-12-01

    To determine the incidence of intraocular pressure (IOP) spikes within the first 30 minutes after sequential argon-Nd:YAG laser peripheral iridotomy (LPI) in patients with angle closure and to explore risk factors for their occurrence. A total of 428 consecutive eyes of 298 patients who had undergone LPI at the Singapore National Eye Centre between June 2011 and August 2011 were reviewed retrospectively. There were 238 primary angle closure suspect eyes, 85 primary angle closure eyes, 92 primary angle closure glaucoma eyes, and 13 acute primary angle closure (APAC) eyes. The pre-LPI IOP and post-LPI IOP, gonioscopic findings, medications, laser parameters, and the need for acute IOP-lowering treatment were recorded. The proportion of patients with a post-LPI IOP elevation ≥8 mm Hg was 10.7% (n=46) and those with a significant IOP spike of ≥30 mm Hg was 31 (7.2%). There were no significant differences between those with or without a post-LPI IOP elevation ≥8 mm Hg and those with or without a post-LPI IOP of ≥30 mm Hg, in terms of age, gender, race, total laser energy used, and seniority of the physician performing the procedure. Patients who experienced IOP spike ≥8 mm Hg were on fewer pre-LPI medications (P=0.009). On logistic regression, patients with APAC had a significantly higher probability of an IOP spike (P=0.003). The incidence of postsequential LPI IOP elevation ≥8 mm Hg was 10.7%. The primary diagnosis of APAC was a risk factor, and using preprocedure ocular hypotensives can potentially reduce their occurrence.

  18. Genome-wide association study and meta-analysis of intraocular pressure

    Science.gov (United States)

    Ozel, A. Bilge; Reed, David M.; Nika, Melisa; Schmidt, Caroline M.; Akbari, Sara; Scott, Kathleen; Rozsa, Frank; Pawar, Hemant; Musch, David C.; Lichter, Paul R.; Gaasterland, Doug; Branham, Kari; Gilbert, Jesse; Garnai, Sarah J.; Chen, Wei; Othman, Mohammad; Heckenlively, John; Swaroop, Anand; Abecasis, Gonçalo; Friedman, David S.; Zack, Don; Ashley-Koch, Allison; Ulmer, Megan; Kang, Jae H.; Liu, Yutao; Yaspan, Brian L.; Haines, Jonathan; Allingham, R. Rand; Hauser, Michael A.; Pasquale, Louis; Wiggs, Janey; Richards, Julia E.

    2014-01-01

    Elevated intraocular pressure (IOP) is a major risk factor for glaucoma and is influenced by genetic and environmental factors. Recent genome-wide association studies (GWAS) reported associations with IOP at TMCO1 and GAS7, and with primary open-angle glaucoma (POAG) at CDKN2B-AS1, CAV1/CAV2, and SIX1/SIX6. To identify novel genetic variants and replicate the published findings, we performed GWAS and meta-analysis of IOP in >6,000 subjects of European ancestry collected in three datasets: the NEI Glaucoma Human genetics collaBORation, GLAUcoma Genes and ENvironment study, and a subset of the Age-related Macular Degeneration-Michigan, Mayo, AREDS and Pennsylvania study. While no signal achieved genome-wide significance in individual datasets, a meta-analysis identified significant associations with IOP at TMCO1 (rs7518099-G, p = 8.0 × 10−8). Focused analyses of five loci previously reported for IOP and/or POAG, i.e., TMCO1, CDKN2B-AS1, GAS7, CAV1/CAV2, and SIX1/SIX6, revealed associations with IOP that were largely consistent across our three datasets, and replicated the previously reported associations in both effect size and direction. These results confirm the involvement of common variants in multiple genomic regions in regulating IOP and/or glaucoma risk. PMID:24002674

  19. Regulation of intraocular pressure by soluble and membrane guanylate cyclases and their role in glaucoma.

    Directory of Open Access Journals (Sweden)

    Emmanuel S Buys

    2014-05-01

    Full Text Available Glaucoma is a progressive optic neuropathy characterized by visual field defects that ultimately lead to irreversible blindness (1, 2. By the year 2020, an estimated 80 million people will have glaucoma, 11 million of which will be bilaterally blind. Primary open-angle glaucoma (POAG is the most common type of glaucoma. Elevated intraocular pressure (IOP is currently the only risk factor amenable to treatment. How IOP is regulated and can be modulated remains a topic of active investigation. Available therapies, mostly geared towards lowering IOP, offer incomplete protection, and POAG often goes undetected until irreparable damage has been done, highlighting the need for novel therapeutic approaches, drug targets, and biomarkers (3, 4. In this review, the role of soluble (nitric oxide (NO-activated and membrane-bound, natriuretic peptide (NP-activated guanylate cyclases that generate the secondary signaling molecule cyclic guanosine monophosphate (cGMP in the regulation of IOP and in the pathophysiology of POAG will be discussed.

  20. Screening of intraocular pressure before routine pupil dilation for retinal photography: Clinical case report

    Directory of Open Access Journals (Sweden)

    Lap-kin Chiang

    2016-12-01

    Full Text Available Introduction: Pharmacologic dilation of the pupil results in twice the sensitivity of detection of diabetic retinopathy compared with undilated retinal examination. The potential risk of acute angle-closure glaucoma after pupil dilation has been hypothesized to be higher in Asian patients with diabetes mellitus. Clinical case: A 61-year-old man with diabetes mellitus and hypertension was incidentally found to have elevated intraocular pressure (IOP before routine retinal photography. He was asymptomatic and the visual acuity was 0.67 for both eyes. An ophthalmologist later found he had anatomical narrow-angle borderline glaucoma. Topical administration of pilocarpine and oral administration of acetazolamide were initiated, and laser iridotomy was later performed. IOP screening: Among 1736 diabetic and/or hypertensive patients who underwent IOP screening, 31 patients (1.8% had IOP of any eye persistently higher than 21 mm Hg on at least two occasions. The mean (standard deviation IOP of the right eye was 24.1 (2.1 mm Hg, while that of the left eye was 24.6 (2.5 mm Hg. Four patients (12.9% were found to have glaucoma, and treatment was initiated by an ophthalmologist. Therefore further study should be conducted to evaluate the cost-effectiveness of IOP screening among this group of patients.

  1. Relationship between hematocrit levels and intraocular pressure in men and women

    Science.gov (United States)

    Cohen, Eytan; Kramer, Michal; Shochat, Tzippy; Goldberg, Elad; Krause, Ilan

    2017-01-01

    Abstract To assess a possible relationship between hematocrit level and intraocular pressure (IOP) in both men and women. Data were collected from medical records of individuals examined at a screening center in Israel between the years 2000 and 2013. Hematocrit levels were categorized as low, normal, and high and by sex; IOP values were categorized as hematocrit for men was 42% to 52% and 37% to 47% for women. In men, mean [95% confidence interval CI)] IOP values by hematocrit level were as follows: below-normal hematocrit, 13.3 mmHg (13.2–13.3), normal hematocrit, 13.5 mmHg (13.4–13.5), above-normal hematocrit, 14.3 mmHg (13.5–15.2) (P hematocrit were found to have a significantly lower odds ratio (95% CI) of having IOP ≥18 mmHg than men with normal hematocrit: nonadjusted model, 0.761 (0.631–0.919); adjusted model, 0.771 (0.638–0.932) (P hematocrit level may also contribute to an elevated IOP in men in addition to the classic risk factors. PMID:29019901

  2. Long-term intraocular pressure fluctuations and risk of conversion from ocular hypertension to glaucoma.

    Science.gov (United States)

    Medeiros, Felipe A; Weinreb, Robert N; Zangwill, Linda M; Alencar, Luciana M; Sample, Pamela A; Vasile, Cristiana; Bowd, Christopher

    2008-06-01

    To investigate whether long-term intraocular pressure (IOP) fluctuations are a risk factor for conversion from ocular hypertension to glaucoma. Observational cohort study. The study included 252 eyes of 126 patients with ocular hypertension observed untreated as part of the Diagnostic Innovations in Glaucoma Study. At baseline, ocular hypertensive eyes had elevated IOP, normal visual fields (VFs) on standard automated perimetry, and normal optic discs as evaluated by stereophotograph assessment. Glaucoma conversion was defined as development of reproducible VF loss or optic disc damage. Analyses included all IOP measurements from the baseline visit to time of progression (for converters) and last follow-up (for nonconverters). Mean IOP and IOP fluctuation were calculated as the arithmetic mean and standard deviation (SD), respectively, of all available IOP measurements per eye. Univariable and multivariable Cox regression analyses were used to evaluate the association between IOP fluctuation and time to progression. Multivariable models adjusted for age, mean IOP, central corneal thickness, vertical cup-to-disc ratio, and pattern SD. Forty eyes of 31 subjects developed glaucoma during follow-up. Mean IOPs during follow-up were 25.4+/-4.2 mmHg for the eyes that converted to glaucoma and 24.1+/-3.5 mmHg for the eyes that did not. Corresponding values for IOP fluctuation were 3.16+/-1.35 mmHg and 2.77+/-1.11 mmHg, respectively. Intraocular pressure fluctuation was not a risk factor for conversion to glaucoma both in univariable analysis (hazard ratio [HR], 1.30 per 1 mmHg higher; 95% confidence interval [CI], 0.76-1.96; P = 0.092) and in multivariable analysis (adjusted HR, 1.08 per 1 mmHg higher; 95% CI, 0.79-1.48; P = 0.620). Mean IOP during follow-up was a significant risk factor for progression both in univariable analysis (HR = 1.16 per 1 mmHg higher; 95% CI, 1.04-1.31; P = 0.010) and in multivariable analysis (adjusted HR, 1.20 per 1 mmHg higher; 95% CI, 1

  3. Clinical factors affecting intraocular pressure change after orbital decompression surgery in thyroid-associated ophthalmopathy

    Directory of Open Access Journals (Sweden)

    Jeong JH

    2016-01-01

    Full Text Available Jae Hoon Jeong,1 Jeong Kyu Lee,1,2 Dong Ik Lee,1 Yeoun Sook Chun,1 Bo Youn Cho2 1Department of Ophthalmology, College of Medicine, Chung-Ang University 2Thyroid Center, Chung-Ang University Hospital, Seoul, Korea Objective: To report the physiological monitoring of intraocular pressure (IOP during the postoperative periods after orbital decompression surgery and ascertain the correlation between the clinical factors and IOP changes.Methods: The medical records of 113 orbits from 60 patients who underwent orbital decompression surgery were reviewed retrospectively. IOP measurement during the postoperative periods was classified based on the postoperative day: week 1 (1–7 days, month 1 (8–41 days, month 2 (42–70 days, month 3 (71–97 days, month 4 (98–126 days, and final (after 127 days. The mean postoperative follow-up was 286.5 days for orbits with at least 6 months of follow-up. Univariate and multivariate linear regression analyses were performed to assess the correlation between the IOP reduction percentage and clinical factors.Results: The mean IOP increased from 16.9 to 18.6 mmHg (10.1% at postoperative week 1 and decreased to 14.4 mmHg (14.5% after 2 months. Minimal little changes were observed postoperatively in the IOP after 2 months. Preoperative IOP had a significant positive effect on the reduction percentage both at postoperative week 1 (β=2.51, P=0.001 and after 2 months (β=1.07, P=0.029, and the spherical equivalent showed a positive correlation with the reduction level at postoperative week 1 (β=1.71, P=0.021.Conclusion: Surgical decompression caused a significant reduction in the IOP in thyroid-associated orbitopathy, and the amount of reduction was closely related to preoperative IOP; however, it may also cause a transient elevation in the IOP during the early postoperative phase in highly myopic eyes. Keywords: Graves’ ophthalmopathy, intraocular pressure, myopia, physiologic monitoring, postoperative periods

  4. Meta-analysis of timolol on diurnal and nighttime intraocular pressure and blood pressure.

    LENUS (Irish Health Repository)

    Lee, Princeton Wen-Yuan

    2012-02-01

    PURPOSE: To evaluate the nighttime intraocular pressure (IOP) and blood pressure (BP) response to timolol treatment in patients with ocular hypertension or primary open-angle glaucoma. METHODS: This was a meta-analysis of previously published studies that must have been randomized, prospective, crossover or parallel, single or double-masked trials. The treatment period must have been >\\/=2 weeks with >\\/=19 patients per treatment arm for a crossover, and >\\/=50 patients for a parallel designed trial. Studies must have included both baseline and treated 24-hour curves. RESULTS: For the IOP analysis, we included 8 articles with 340 patients. A reduction from baseline was observed for timolol at each time point and for the 24-hour curve (p<\\/=0.009). When 2 studies, in which timolol was used adjunctively, were removed, a similar difference was observed as above at each time point and for the 24-hour curve (p<\\/=0.003). In 2 studies, there were small reductions from baseline for the mean diastolic and systolic BPs at most time points and for the 24-hour curve (3.9 and 4.2 mmHg, respectively) with timolol treatment. The ocular perfusion pressure did not show any difference between baseline and timolol treatment at any time point or for the 24-hour curve (p>0.05). CONCLUSIONS: This meta-analysis suggests that topical timolol therapy provides an ocular hypotensive effect over the 24-hour curve, including the nighttime hours, and while small reductions in the systolic and diastolic pressures occur, the ocular perfusion pressure is not altered over 24 hours.

  5. EVOLUTION THE CONCEPTS OF ROLE OF INTRAOCULAR PRESSURE IN GLAUCOMA PROGRESSION (REVIEW

    Directory of Open Access Journals (Sweden)

    N. I. Kurysheva

    2016-01-01

    Full Text Available The role of elevated intraocular pressure (IOP in the progression of glaucoma optical neuropathy has emphasized repeatedly. The question about the role of elevated IOP as the underlying cause of glaucoma arose in the early 1960s. However, epidemiological studies have questioned the role of IOP as a diagnostic criterion for glaucoma, due to the relatively rare detection the disease among those with ocular hypertension and frequent detection of glaucoma with normal IOP. Multicenter studies determining the role of antihypertensive therapy in the treatment of glaucoma, have shown the importance of reducing IOP: decricing IOP at 1 mm Hg reduced the risk of developing glaucoma on 10-19%. In addition, it was found that the rate of glaucoma progression is very variable. It depends not only on the form of glaucoma, but also on other factors such as the stage of disease and therapy. Swedish study shown normal-tension glaucoma often progressed among the patients with more aggressive treatment such as argon laser trabeculoplasty or trabeculectomies. According to the study’s data, age is the most important risk factor for the progression of normal-tension glaucoma. Such questions as fluctuations in IOP, reduction of retrobulbar blood flow, antihypertensive treatment on the progression of glaucoma are still discussed. Despite the fact that the latter UKGTS multicenter study (2014 showed a decrease in the rate of progression of glaucoma in patients treated with latanoprost, a high percentage of non-treated patients didn’t have disease’s progression. In this regard, the role of IOP as main starting factor in glaucoma pathogenesis is still open.

  6. Autotaxin-lysophosphatidic acid axis is a novel molecular target for lowering intraocular pressure.

    Directory of Open Access Journals (Sweden)

    Padma Iyer

    Full Text Available Primary open-angle glaucoma is the second leading cause of blindness in the United States and is commonly associated with elevated intraocular pressure (IOP resulting from diminished aqueous humor (AH drainage through the trabecular pathway. Developing effective therapies for increased IOP in glaucoma patients requires identification and characterization of molecular mechanisms that regulate IOP and AH outflow. This study describes the identification and role of autotaxin (ATX, a secretory protein and a major source for extracellular lysophosphatidic acid (LPA, in regulation of IOP in a rabbit model. Quantitative proteomics analysis identified ATX as an abundant protein in both human AH derived from non-glaucoma subjects and in AH from different animal species. The lysophospholipase D (LysoPLD activity of ATX was found to be significantly elevated (by ∼1.8 fold; n=20 in AH derived from human primary open angle glaucoma patients as compared to AH derived from age-matched cataract control patients. Immunoblotting analysis of conditioned media derived from primary cultures of human trabecular meshwork (HTM cells has confirmed secretion of ATX and the ability of cyclic mechanical stretch of TM cells to increase the levels of secreted ATX. Topical application of a small molecular chemical inhibitor of ATX (S32826, which inhibited AH LysoPLD activity in vitro (by >90%, led to a dose-dependent and significant decrease of IOP in Dutch-Belted rabbits. Single intracameral injection of S32826 (∼2 µM led to significant reduction of IOP in rabbits, with the ocular hypotensive response lasting for more than 48 hrs. Suppression of ATX expression in HTM cells using small-interfering RNA (siRNA caused a decrease in actin stress fibers and myosin light chain phosphorylation. Collectively, these observations indicate that the ATX-LPA axis represents a potential therapeutic target for lowering IOP in glaucoma patients.

  7. The Relationship Between Systemic Blood Pressure and Intraocular ...

    African Journals Online (AJOL)

    The results showed that mean IOP was higher in hypertensive than normotensive subjects (p< 0.001) and there was a significant correlation between blood pressure distribution and IOP in the combined population. Therefore patients with high blood pressure should be screened for open angle glaucoma as a preventive ...

  8. The effects of cigarette smoking on intraocular pressure and arterial ...

    African Journals Online (AJOL)

    This study was designed to determine the effects of cigarette Smoking on intra ocular pressure and arterial blood pressure of normotensive young male adults. Fifty male students (who met the screening conditions and devoid of obvious ocular pathology and systemic diseases and nonsmokers) had their intra ocular ...

  9. Comparison of Tono-Pen AVIA intraocular pressure measurements performed at limbus with central corneal Tono-Pen AVIA intraocular pressure.

    Science.gov (United States)

    Sharma, Reetika; Majumdar, Saptorishi; Sobti, Amit; Arora, Tarun; Agarwal, Tushar; Dada, Tanuj

    2013-07-01

    To compare Tono-Pen AVIA (TPA) intraocular pressure (IOP) measurements performed at the limbus with central corneal Tono-Pen AVIA (TPA) intraocular pressure. Fifty-one patients attending our outpatient department with a best corrected visual acuity of ≥ 20/40, no corneal disease, and no astigmatism greater than 1.5 diopters underwent routine ophthalmological examination. Patients with ametropia greater than or equal to ± 5 diopters, a history of recent contact lens wear, and central corneal thickness of 550 µm were excluded from the study. IOP was recorded first in the corneal center, followed by tonometry measurements obtained from the temporal, nasal, superior, and inferior limbus using TPA. IOP measurements were compared using the paired t test. Correlation was derived by Pearson correlation coefficient, and regression equations were derived. The mean age of patients in our study was 43.86 ± 15.39 years. The mean TPA IOP from the central cornea was 16.59 ± 3.75 mm Hg. There was a statistically significant difference between Tono-Pen IOP from the central cornea and that recorded from all 4 limbal positions (P < 0.001). There was a positive correlation between the central and the limbal IOP obtained with Tono-Pen. Correlation was maximum for the temporal limbus. Limbal TPA IOP is significantly higher than central TPA IOP. There remains a good correlation between central and limbal IOP. This was found to be greatest for the temporal limbus.

  10. Reproducibility of postural changes in intraocular pressure with the Tono-Pen and Pulsair tonometers.

    Science.gov (United States)

    Wilson, M R; Baker, R S; Mohammadi, P; Wheeler, N C; Lee, D A; Scott, C

    1993-10-15

    Reproducibility of measurements of postural changes in intraocular pressure was determined by using the Tono-Pen (Mentor O & O, Inc., Norwell, Massachusetts) and Pulsair (Keeler Instruments, Inc., Broomhall, Pennsylvania) tonometers. Thirty subjects had three repeated sitting and reclining measurements performed on three separate visit days. Reproducibility coefficients of 3.3% for the Tono-Pen and 6.3% for the Pulsair were obtained for the within-visit postural change measurements. Across-visit reproducibility coefficients were 7.9% and 26.2% for the Tono-Pen and Pulsair, respectively. The estimated standard deviations for both the within-visit and across-visit postural change measurements were high for both instruments. These results indicate poor reproducibility of measurements of postural changes in intraocular pressure.

  11. [The effect of crystalline lens extraction on intraocular pressure in patients with primary open-angle glaucoma].

    Science.gov (United States)

    Macarie, S; Macarie, Daniela

    2013-01-01

    This issue presents the results of a study on patients with cataract and primary open angle glaucoma who suffered lens extraction for cataract. We analise the effects of the lens extraction on the level of intraocular pressure at this patients.

  12. Effects of tramadol and acepromazine on intraocular pressure and pupil diameter in young healthy cats

    OpenAIRE

    Schroder, Deise Cristine; Monteiro, Bianca Garay; Pytlak, Deborah Braga; Souza, Mayara Carvalho de; Mendonça, Adriane Jorge; Ribeiro, Alexandre Pinto

    2018-01-01

    ABSTRACT: This study aimed to investigate the effects of the systemic administration of acepromazine, tramadol and the association of both on intraocular pressure (IOP) and pupil diameter (PD) in young healthy cats. Cats were randomly allocated into three groups (n=10/each) and intramuscular acepromazine (AG), tramadol (TG) or acepromazine combined with tramadol (ATG) were injected. PD (electronic caliper) and IOP (applanation tonometry) were assessed before (baseline) and following 15, 30, 6...

  13. Intravenous paracetamol and intraocular pressure reduction: mannitol may also be involved

    Directory of Open Access Journals (Sweden)

    Allegaert K

    2016-09-01

    Full Text Available Karel Allegaert1,2 1Intensive Care, Department of Surgery, Erasmus MC Sophia Children’s Hospital, Rotterdam, the Netherlands; 2Department of Development and Regeneration, KU Leuven, BelgiumI read, with great interest, the paper on the intraocular pressure-lowering properties of intravenous paracetamol (acetaminophen recently published in this journal by van den Heever and Meyer.1 The authors documented a decrease from baseline in mean intraocular pressure of 15.7% in a 6-hour time interval following intravenous paracetamol (1 g Perfalgan®, Bristol-Myers Squibb, New York, NY, USA administration. This mean decrease was moderate but relevant when compared to, for example, topical timolol (–25.3%, single drop 0.5% timolol maleate or oral acetazolamide (–23.1%, 250 mg. Although the authors provided potential relevant mechanistic arguments in support of a link between paracetamol administration and intraocular pressure through the endocannabinoid system, we would like to draw attention to the fact that – when intravenous paracetamol is administered – a relevant amount of mannitol is coadministered.View the original paper by van den Heever and Meyer

  14. 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)

  15. The effects of graded intraocular pressure challenge on the optic nerve head.

    Science.gov (United States)

    Patel, Nimesh; McAllister, Faith; Pardon, Laura; Harwerth, Ronald

    2018-04-01

    Intraocular pressure (IOP) is an important risk factor for glaucoma, and the response of the ONH and surrounding tissues to elevated IOP are often investigated to better understand pathophysiology. In vivo structure including that of the optic nerve head (ONH) and surrounding tissue of the eye are often assessed using optical coherence tomography (OCT). With advances in OCT technology, both large vessels and capillaries can be imaged non-invasively (OCT Angiography). Because a significant portion of retinal thickness is comprised of vasculature, the purpose of the current study was to investigate OCT structural and vascular changes in healthy non-human primate eyes with systematic graded increases and decreases in IOP. Six healthy animals with no previous experimental intervention were used. The pressure in the anterior chamber was adjusted from 10 mmHg to 60 mmHg and back to 10 mmHg in 10 mmHg steps every 10 min. Using optical coherence tomography (OCT), retinal nerve fiber layer (RNFL) thickness, minimum rim width (MRW), Bruch's membrane opening (BMO) size and relative height, anterior lamina cribrosa surface (ALCS) depth, choroidal thickness, and angiography (OCTA) were quantified. With IOP challenge there were significant changes in all morphological measures quantified (p < 0.01) other than BMO size (p = 0.30) and RNFL thickness (p = 0.29). Specifically, the position of the BMO was sensitive to both an increase and decease in IOP. The inner retinal capillary density gradually decreased with increasing IOP, reaching statistical significance when pressure exceeded 50 mmHg, but returned when IOP was reduced. The average choroidal thickness around the ONH decreased for elliptical annuli 500-1000 μm and 1000-1500 μm, from the BMO, with increasing IOP (p < 0.01). For the 1000-1500 μm annulus, choroid thickness did not return to baseline with IOP reduction. Similarly, the MRW decreased with increase in IOP, but with pressure

  16. Travoprost lowers intraocular pressure in healthy student volunteers ...

    African Journals Online (AJOL)

    ... African volunteers in a randomized double masked, placebo controlled, crossover, single centre study. Pulse rate, systolic and diastolic blood pressure, and respiratory rate were also measured. Mean IOP was lower than baseline values up to 72 hours after instillation but the mean IOP was significantly lower in the eyes ...

  17. Identifying the critical factors that influence intraocular pressure using an automated regression tree

    Directory of Open Access Journals (Sweden)

    Nishanee Rampersad

    2017-02-01

    Full Text Available Background: Assessment of intraocular pressure (IOP is an important test in glaucoma. In addition, anterior segment variables may be useful in screening for glaucoma risk. Studies have investigated the associations between IOP and anterior segment variables using traditional statistical methods. The classification and regression tree (CART method provides another dimension to detect important variables in a relationship automatically. Aim: To identify the critical factors that influence IOP using a regression tree. Methods: A quantitative cross-sectional research design was used. Anterior segment variables were measured in 700 participants using the iVue100 optical coherence tomographer, Oculus Keratograph and Nidek US-500 ultrasonographer. A Goldmann applanation tonometer was used to measure IOP. Data from only the right eyes were analysed because of high levels of interocular symmetry. A regression tree model was generated with the CART method and Pearson’s correlation coefficients were used to assess the relationships between the ocular variables. Results: The mean IOP for the entire sample was 14.63 mmHg ± 2.40 mmHg. The CART method selected three anterior segment variables in the regression tree model. Central corneal thickness was the most important variable with a cut-off value of 527 µm. The other important variables included average paracentral corneal thickness and axial anterior chamber depth. Corneal thickness measurements increased towards the periphery and were significantly correlated with IOP (r ≥ 0.50, p ≤ 0.001. Conclusion: The CART method identified the anterior segment variables that influenced IOP. Understanding the relationship between IOP and anterior segment variables may help to clinically identify patients with ocular risk factors associated with elevated IOPs.

  18. Correlation between intraocular pressure and the biometric structure of the anterior chamber in patients of chronic renal failure with hemodialysis

    Directory of Open Access Journals (Sweden)

    Zhi-Ying Yu

    2017-02-01

    Full Text Available AIM: To investigate the correlation between intraocular pressure(IOPchanges pre- and post-hemodialysis(HDand the biometric structure of the anterior chamber in patients of chronic renal failure. METHODS: Fifty-two patients(take right eye as study onewith hemodialysis that were diagnosed with chronic renal failure by nephrology in our hospital from January 2015 to December 2015 were collected. Fifty-two eyes were divided into four groups based on Shaffer classification combined with ultrasound biomicroscopy(UBMand gonioscopy manifestations: wide angle group, narrow angle group, extremely narrow group and close angle group. Venous blood was collected to get plasma colloid osmotic pressure before HD and within 60s after HD. IOP was measured with rebound intraocular pressure gauge in a supine positon approximately 30min before starting HD, 2h after HD begin and approximately 30min after HD ending. Approximately 30min before and after HD, central corneal thickness was measured with corneal endothelial cell counter, central anterior chamber depth and lens thickness were taken by A scan, angle opening distance, trabecular iris angle, iris thickness and ciliary body thickness were measured by UBM. RESULTS: Plasma osmotic pressure reduced after HD, the difference was statistically significant(t=3.04, PF=41.69, PPPF=6.44, PPt=2.61, PCONCLUSION: The influence of hemodialysis on IOP is related to the biometric structure of the anterior chamber. And extremely narrow angle is risk factor of elevated IOP during hemodialysis, narrow angle may be a risk factor. While patients with wide angle is relatively safe. We suggest to take ocular examination as early as possible for patients with hemodialysis, and focus on patients with narrow angle.

  19. Intraocular pressure variation following retrobulbar anaesthesia among the different sex, age and ethnic groups in Malaysia.

    Science.gov (United States)

    Lee, F N; Kong, V Y; Lee, G P; Ho, K H; Choon, S C; Hoh, H B

    1999-12-01

    A total of 114 patients (48 Chinese, 34 Malay and 32 Indian) undergoing extracapsular cataract extraction (ECCE) with intraocular lens implantation, were enrolled. All were given 3 ml of local anaesthetic (combination of equal amounts of lignocaine 2% and bupivacaine 0.5%) using retrobulbar technique. Intraocular pressure (IOP) was measured at different time intervals; before, immediately after and 5 minutes after injection with Honan balloon compression. Mean IOP increased by 5.0 mmHg immediately after injection (p age groups, Chinese patients demonstrated the highest IOP rise following retrobulbar anaesthesia. This is the first study to demonstrate the influence of race in the IOP response with Chinese subjects having the highest IOP rise.

  20. Oculab Tono-Pen, Goldmann applanation tonometry, and pneumatic tonometry for intraocular pressure assessment in gas-filled eyes.

    Science.gov (United States)

    Hines, M W; Jost, B F; Fogelman, K L

    1988-08-15

    We performed 84 intraocular pressure measurements with the Oculab Tono-Pen, Goldmann applanation tonometer, and pneumatic tonometer in 47 eyes that had undergone pars plana vitrectomy and gas-fluid exchange. Measurements made by using the Tono-Pen were accurate when compared to those made by Goldmann tonometry (mean difference, 0.74 mm Hg). In a subset of eyes with increased intraocular pressure (greater than or equal to 25 mm Hg), the Tono-Pen provided measurements similar to those made by Goldmann applanation tonometry (P greater than .60), with only three of 39 readings (8%) underestimating the Goldmann pressure by more than 3 mm Hg. Pneumatic tonometry significantly underestimated the intraocular pressure in eyes with increased pressure (P less than .001), with 20 of 39 readings (51%) underestimating the Goldmann pressure by 5 mm Hg or more.

  1. Prospective Comparative Analysis of 4 Different Intraocular Pressure Measurement Techniques and Their Effects on Pressure Readings.

    Science.gov (United States)

    Berk, Thomas A; Yang, Patrick T; Chan, Clara C

    2016-10-01

    To compare intraocular pressure (IOP) measurement using the Goldmann applanation tonometry (GAT) without fluorescein, with fluorescein strips, with fluorescein droplets, and IOP measurement with Tono-Pen Avia (TPA). This was a prospective comparative clinical analysis. It was performed in clinical practice. The study population consisted of 40 volunteer patients, 1 eye per patient. All patients who were 18 years and older having routine ophthalmological examination were eligible to participate. Active corneal abrasions and/or ulcers, previous glaucoma surgery, or prostheses interfering with GAT measurement were excluded. GAT IOP was measured first without fluorescein, then with fluorescein strip, then with fluorescein droplet, and finally with the TPA device. The main outcome measure was central corneal IOP. Mean±SD IOP measurements for GAT without fluorescein, with fluorescein strip, with fluorescein droplet, and for TPA groups were 12.65±3.01, 14.70±2.82, 15.78±2.64, and 16.33±3.08 mm Hg, respectively. Repeated-measures analysis of variance corrected with the Greenhouse-Geisser estimate ([Latin Small Letter Open E]=0.732) showed that measuring technique had a significant effect on IOP measurements (F2.20,85.59=34.66, P<0.001). The pairwise post hoc testing showed statistically significant mean differences (P≤0.001) between all techniques except when GAT with fluorescein droplet was compared with TPA (P=0.222). The Bland-Altman analyses showed 95% limits of agreement maximum potential discrepancies in measurement ranging from 5.89 mm Hg in the GAT with fluorescein strip versus droplet compared with 11.83 mm Hg in the GAT with fluorescein strip versus TPA comparison. IOP measurement technique significantly impacted the values obtained. The ophthalmologist should ensure consistent measurement technique to minimize variability when following patients.

  2. Effect of sildenafil citrate on intraocular pressure and blood pressure in human volunteers.

    Science.gov (United States)

    Gerometta, Rosana; Alvarez, Lawrence J; Candia, Oscar A

    2011-07-01

    Anecdotal reports have suggested that the vasodilator, sildenafil citrate, which evokes its effect via a select inhibition of PDE5, has the potential to increase intraocular pressure (IOP) in some individuals. An ocular hypertensive effect by sildenafil was also recently described in a sheep animal model. In contrast, clinical studies have not found a direct association between sildenafil ingestion (commonly consumed as Viagra) and changes in IOP. However, some such studies also reported no effects of sildenafil on systemic blood pressure (BP) at the time of the IOP determination. Given this surprising result, our purpose was to repeat a study in human volunteers in the city of Corrientes, Argentina to corroborate the effects of sildenafil on human IOP and systemic BP. For the present study, 9 healthy volunteers (male and female, 18-74 years old) were selected as subjects after ophthalmic and cardiovascular evaluation indicated that they exhibited normal parameters for their age. In a masked, placebo-controlled study, the subjects ingested 100 mg sildenafil citrate (provided as Vorst from Laboratorios Bernabo, Argentina) in one session, and a placebo on a second separate occasion. IOP was measured with a Goldman applanation tonometer by an ophthalmologist, and BP by a second physician, neither of whom witnessed the tablet ingestion by the volunteers, nor provided with information on the nature of the test compounds. A third individual administered the tablets. The average baseline IOP of this group of 9 was 13.1 ± 0.6 mm Hg. Subsequent to sildenafil ingestion, IOP increased by 26% to 16.5 ± 0.8 mm Hg 60 min later (P < 0.005, as paired data), and returned to control values within 2 h. Both systolic and diastolic BP were significantly reduced by sildenafil ingestion. At the point of maximal systemic hypotension (90 min), the systolic and diastolic pressures declined by 15% and 13%, respectively. No significant changes in IOP or BP were recorded after

  3. Measuring elevated intracranial pressure through noninvasive methods

    DEFF Research Database (Denmark)

    Kristiansson, Helena; Nissborg, Emelie; Bartek, Jiri

    2013-01-01

    Elevated intracranial pressure (ICP) is an important cause of secondary brain injury, and a measurement of ICP is often of crucial value in neurosurgical and neurological patients. The gold standard for ICP monitoring is through an intraventricular catheter, but this invasive technique...

  4. Asymptomatic proteinuria and elevated blood pressure among ...

    African Journals Online (AJOL)

    Background: Hypertension and proteinuria are known risk factors for cardiovascular disease and renal impairment. Early detection and treatment will reduce morbidity and mortality associated with them. Objective: To determine the prevalence of asymptomatic proteinuria with or without elevated blood pressure among ...

  5. Isoflurane and ketamine:xylazine differentially affect intraocular pressure-associated scotopic threshold responses in Sprague-Dawley rats.

    Science.gov (United States)

    Choh, Vivian; Gurdita, Akshay; Tan, Bingyao; Feng, Yunwei; Bizheva, Kostadinka; McCulloch, Daphne L; Joos, Karen M

    2017-10-01

    Amplitudes of electroretinograms (ERG) are enhanced during acute, moderate elevation of intraocular pressure (IOP) in rats anaesthetised with isoflurane. As anaesthetics alone are known to affect ERG amplitudes, the present study compares the effects of inhalant isoflurane and injected ketamine:xylazine on the scotopic threshold response (STR) in rats with moderate IOP elevation. Isoflurane-anaesthetised (n = 9) and ketamine:xylazine-anaesthetised (n = 6) rats underwent acute unilateral IOP elevation using a vascular loop anterior to the equator of the right eye. STRs to a luminance series (subthreshold to -3.04 log scotopic cd s/m 2 ) were recorded from each eye of Sprague-Dawley rats before, during, and after IOP elevation. Positive STR (pSTR) amplitudes for all conditions were significantly smaller (p = 0.0001) for isoflurane- than for ketamine:xylazine-anaesthetised rats. In addition, ketamine:xylazine was associated with a progressive increase in pSTR amplitudes over time (p = 0.0028). IOP elevation was associated with an increase in pSTR amplitude (both anaesthetics p ketamine:xylazine and isoflurane were similar (66.3 ± 35.5 vs. 54.2 ± 24.1 µV, respectively). However, the fold increase in amplitude during IOP elevation was significantly higher in the isoflurane- than in the ketamine:xylazine-anaesthetised rats (16.8 ± 29.7x vs. 2.1 ± 2.7x, respectively, p = 0.0004). The anaesthetics differentially affect the STRs in the rat model with markedly reduced amplitudes with isoflurane compared to ketamine:xylazine. However, the IOP-associated enhancement is of similar absolute magnitude for the two anaesthetics, suggesting that IOP stress and anaesthetic effects operate on separate retinal mechanisms.

  6. Utility of the Tono-Pen in Measuring Intraocular Pressure in Trinidad: A Cross-sectional Study.

    Science.gov (United States)

    Billy, A; David, P E; Mahabir, A K; Seerattan, C P; Street, J M; Walcott, V D; Yarna, R J; Murray, D C; Maharaj, R G

    2015-09-01

    To determine the sensitivity and specificity of the Reichert™ Tono-Pen AVIA® when used by novice medical students in an ethnically diverse population in Trinidad. Participants were residents of Trinidad between the ages of 20 and 90 years attending the Ophthalmology Clinic at the Eric Williams Medical Sciences Complex (EWMSC). Intraocular pressure (IOP) was measured using the Goldmann applanation tonometer (the gold standard) for ophthalmology clinic patients as part of their routine care. Intraocular pressure measurements were then taken using the Tono-Pen. One hundred persons participated, consisting of Indo-Trinidadians (55%), Afro-Trinidadians (36%), Mixed (8%) and 1% of Caucasian descent. Fourteen per cent reported a diagnosis of glaucoma, with 70.6% of these being of African descent. One hundred and ninety-eight readings of IOP were taken. At a cut-off point of 21 mmHg, there were nine true positives, four false positives, seven false negatives and 178 true negatives. The sensitivity and specificity were found to be 56.3% (95% CI 33.2, 76.9) and 97.8% (95% CI 94.5, 99.1), respectively. The positive predictive value was calculated as 69.2% (95% CI 42.4, 87.3) while the negative predictive value was 96.2% (95% CI 92.4, 98.2). The prevalence of elevated IOP in this population was 8.1% (95% CI 4.8, 13.0). The likelihood ratio of a positive result was calculated to be 25.6 (95% CI 8.6, 73.9). The high specificity and negative predictive value suggests that the Tono-Pen can be used with minimal training, and can prove beneficial at the primary care level in the exclusion of increased IOP in an ethnically diverse high-risk Caribbean population.

  7. Effect of persistent high intraocular pressure on microstructure and hydraulic permeability of trabecular meshwork

    Science.gov (United States)

    Mei, Xi; Ren, Lin; Xu, Qiang; Zheng, Wei; Liu, Zhi-Cheng

    2015-05-01

    As the aqueous humor leaves the eye, it first passes through the trabecular meshwork (TM). Increased flow resistance in this region causes elevation of intraocular pressure (IOP), which leads to the occurrence of glaucoma. To quantitatively evaluate the effect of high IOP on the configuration and hydraulic permeability of the TM, second harmonic generation (SHG) microscopy was used to image the microstructures of the TM and adjacent tissues in control (normal) and high IOP conditions. Enucleated rabbit eyes were perfused at a pressure of 60 mmHg to achieve the high IOP. Through the anterior chamber of the eye, in situ images were obtained from different depths beneath the surface of the TM. Porosity and specific surface area of the TM in control and high IOP conditions were then calculated to estimate the effect of the high pressure on the permeability of tissue in different depths. We further photographed the histological sections of the TM and compared the in situ images. The following results were obtained in the control condition, where the region of depth was less than 55 μm with crossed branching beams and large pores in the superficial TM. The deeper meshwork is a silk-like tissue with abundant fluorescence separating the small size of pores. The total thickness of pathway tissues composed of TM and juxtacanalicular (JCT) is more than 100 μm. After putting a high pressure on the inner wall of the eye, the TM region progressively collapses and decreases to be less than 40 μm. Fibers of the TM became dense, and the porosity at 34 μm in the high IOP condition is comparable to that at 105 μm in the control condition. As a consequent result, the permeability of the superficial TM decreases rapidly from 120 μm2 to 49.6 μm2 and that of deeper TM decreases from 1.66 μm2 to 0.57 μm2. Heterogeneity reflected by descent in permeability reduces from 12.4 μm of the control condition to 3.74 μm of the high IOP condition. The persistently high IOP makes the TM

  8. Effects of Cataract Surgery on Intraocular Pressure in Patients with and without Glaucoma

    Directory of Open Access Journals (Sweden)

    Tülin İsmi

    2013-06-01

    Full Text Available Pur po se: To evaluate the effects of phacoemulsification surgery with primary intraocular lens (IOL implantation on intraocular pressure (IOP in various types of glaucoma patients with visually significant cataract and to compare these results with cataract patients without glaucoma. Ma te ri al and Met hod: This retrospective study included consecutive cases of 21 primary open-angle glaucoma patients, 13 primary angle-closure glaucoma (PACG patients, 11 pseudoexfoliation glaucoma patients, and 21 control eyes without any type of glaucoma; all patients had co-existing cataract. Visual acuities, IOP, number of glaucoma medications used, anterior chamber depth (ACD, and gonioscopic evaluations were noted both pre- and postoperatively. Phacoemulsification and IOL implantations were performed via clear corneal incisions in the whole study group. Study group was followed-up for six months. Re sults: Postoperative visits at the 1st, 3rd, and 6th months were noted. After surgery, visual acuities improved significantly (p=0.001 in all groups. Intraocular pressures decreased in all groups postoperatively, but the change was statistically significant in the PACG group (p=0.013. Increase in ACD was significant in PACG group (p=0.001. Widening of iridocorneal angle and decrease in the number of antiglaucoma drugs were observed in all groups, but these were significant in the PACG group (p=0.001 and p<0.05, respectively. Dis cus si on: In glaucoma patients with co-existing cataract, phacoemulsification surgery allows both the visual rehabilitation and IOP control. This IOP lowering effect is seen most markedly in the PACG group. (Turk J Ophthalmol 2013; 43: 167-72

  9. The relationship among race, iris color, central corneal thickness, and intraocular pressure.

    Science.gov (United States)

    Semes, Leo; Shaikh, Adam; McGwin, Gerald; Bartlett, Jimmy D

    2006-07-01

    Central corneal thickness (CCT) influences applanation intraocular pressure (IOP) measurement. The present study sought to determine whether iris color might represent a qualitative surrogate for CCT or race, and therefore differential risk for elevated IOP and, consequently, developing glaucoma. Eligible patients included those with best-corrected visual acuity (BCVA) better than 20/40 and who had not worn contact lenses within 24 hours. Exclusion criteria were prior ophthalmic surgery, topical ocular or systemic medication that would influence IOP, previous ocular inflammatory conditions, or current treatment for ophthalmic treatment. Data collection included demographic (name, date of birth, race), BCVA, and iris color. Iris color was judged according to a purpose-developed chart (white: blue, green, brown or black: brown) and patients were assigned to one of four groups. Goldmann applanation tonometry and pachymetry measurements were performed consecutively. To attain a power of 90% to find a difference of 40 microm with alpha iris colors revealed no statistically significant difference among the three groups of whites: blue (552 microm), green (552 microm), and brown (562 microm). The same held true when comparing IOP and CCT-adjusted IOP with iris color: blue-15.2, 15.1, green-15.4, 15.2, and brown-14.7, 14.0. When comparing CCT between whites and blacks, CCT was significantly thinner in blacks (533 microm), whether evaluating all whites (555 microm, p = 0.03) or comparing only the brown-iris white group with the black group (562 microm vs. 533 microm, p = 0.03). Mean CCT-adjusted IOP was barely significantly different between whites (14.8) and blacks (16.7) (p = 0.04). These results suggest that iris color is not associated with CCT and apparently iris color does not influence measured IOP. We were able to establish a relationship between race and IOP when adjusting IOP for CCT. Our data show a significantly higher CCT-adjusted IOP for blacks than whites

  10. Visual acuity and intraocular pressure after Descemet's stripping endothelial keratoplasty in eyes with and without preexisting glaucoma.

    Science.gov (United States)

    Vajaranant, Thasarat S; Price, Marianne O; Price, Francis W; Gao, Weihua; Wilensky, Jacob T; Edward, Deepak P

    2009-09-01

    (1) To characterize the pattern of intraocular pressure (IOP) changes after Descemet's stripping endothelial keratoplasty (DSEK) in patients without preexisting glaucoma and in those with preexisting glaucoma, with and without prior glaucoma surgery. (2) To compare vision and IOP outcomes among the 3 groups. A retrospective chart review. A total of 805 DSEK cases performed in 641 patients by a single surgeon from December 2003 to August 2007 were available in the database. Only the first-treated eye of each patient with at least 1-year follow-up was included. Four hundred cases qualified: 315 eyes had no glaucoma (C); 64 eyes had glaucoma with no previous glaucoma surgery (G); and 21 eyes had prior glaucoma surgery (GS). Eyes with preexisting retinal problems were included in the analysis. Data analysis included calculation of incidence of postoperative IOP elevation. The study criteria for postoperative IOP elevation were IOP > or =24 mmHg or IOP increase > or =10 mmHg from baseline. Kruskal-Wallis test was used to compare visual acuity (VA) and IOP among the 3 groups preoperatively and at 1-, 3-, 6-, and 12-month postoperative visits. Visual acuity (Snellen) and IOP (millimeters of mercury). The incidence of postoperative IOP elevation by the study criteria was 35%, 45%, and 43% for groups C, G, and GS, respectively. Elevated IOP was medically managed by initiating or increasing glaucoma medications or reducing steroids in 27%, 44%, and 38% of the patients in groups C, G, and GS, respectively. A subsequent glaucoma procedure was performed in 0.3%, 5%, and 19% of patients in groups C, G, and GS, respectively. Only the control group had statistically significant IOP elevation at 12 months (median increase of 2 mmHg) when compared with baseline (Preferences.

  11. Intraocular pressure and Schirmer tear test values in maned wolf (Chrysocyon brachyurus

    Directory of Open Access Journals (Sweden)

    Cristiane S. Honsho

    Full Text Available Abstract: The purpose of this study was to establish baseline data on lacrimal quantity (STT-1 and intraocular pressure (IOP in captive maned wolves. Ten healthy adult maned wolves were contained with a snare pole and muzzle and kept in decubitus of the left side. STT-1 measurement was performed on the lateral third of the lower conjunctival sac for one minute. The cornea was desensitized and intraocular pressure was measured with an tonopen. Average STT-1 in both eyes was 11±5mm.min-1, with no statistical difference between the left and right eye (p=0.960. Average IOP in both eyes was 20±6mmHg, with no statistical difference between the left and right eye (p=0.836. Average STT-1 was lower than, and IOP was the same as normal levels found in dogs. There was no statistical difference in the age of the animals, and STT-1 and IOP values. In the present paper, average maned wolf STT-1 levels were lower compared with those found in dogs, while the IOP was the same in maned wolves as in dogs. Due to the increased incidence in providing emergency care for maned wolf victims of road kill and fires, determination reference values of ocular parameters may improve the correct diagnosis and treatment of the disease.

  12. Influence of gross saponins from tribulus terrestris L on SOD activity and MDA content for chronic high intraocular pressure in rabbit

    Directory of Open Access Journals (Sweden)

    Nuo Li

    2013-05-01

    Full Text Available AIM:To observe influence of gross saponins from tribulus terrestris L(GSTTon SOD activity and MDA content for chronic high intraocular pressure in rabbit, and discusses the retina oxidative damage inhibition on chronic high intraocular pressure model of rabbit. METHODS:Totally 24 healthy New Zealand rabbits were randomly divided into 4 groups: normal control group(A group; high intraocular pressure model blank group(B group; high intraocular pressure model with GSTT treated group(C group; high intraocular pressure model with Erigeron brevicapas hand mass(EBHMtreated group(D group. High intraocular pressure model was induced by 20g/L methylcellulose injection into the anterior chamber in B group, C group and D group. D group was injected 5 mg/kg GSTT and C group was injected 4.5mg/kg EBHM and measured intraocular pressure with Schiotz tonometer every day for 4 weeks. The retina tissue superoxide dismutase(SODand maleic dialdehyde(MDAcontent were detected 28 days later. RESULTS: After glaucoma model of rabbit eyes were established, the intraocular pressure during observation period was maintained in 32-39mmHg; High intraocular pressure model blank group and normal control group, EBHM treatment group, GSTT treatment group were compared, the differences of retina MDA, SOD content had statistical significance(P0.05; EBHM treatment group, GSTT treatment group and normal control group were compared, the content of MDA in the retina was still slightly higher(P<0.05, the content of SOD slightly lower(P<0.05 CONCLUSION: GSTT can effectively improve the retina SOD activity of chronic high intraocular pressure in rabbit and reduce the content of MDA, which has a protective effect of persistent high intraocular retinal oxidative stress.

  13. Effect of Different Head Positions in Lateral Decubitus Posture on Intraocular Pressure in Treated Patients With Open-Angle Glaucoma.

    Science.gov (United States)

    Lee, Tae-Eun; Yoo, Chungkwon; Lin, Shan C; Kim, Yong Yeon

    2015-11-01

    To investigate the effects of different head positions in the lateral decubitus posture on intraocular pressure (IOP) in medically treated patients with open-angle glaucoma (OAG). Prospective observational study. setting: Institutional. Twenty patients with bilateral OAG who received only latanoprost as treatment. IOP was measured using an ICare Pro tonometer in the sitting, supine, right, and left lateral decubitus posture. In lateral decubitus posture, IOP measurements were taken with 3 different head positions (30 degrees higher than, 30 degrees lower than, and parallel to the center of the thoracic vertebra) in a randomized sequence. Comparison of the IOPs between the dependent (lower-sided) and nondependent eyes in the lateral decubitus postures with different head positions. We also analyzed the differences in IOPs between the better and worse eyes. IOP was higher in the dependent eyes than in the nondependent eyes in lateral decubitus posture, regardless of the head position (all P posture or head position were not significantly different between the better and worse eyes. Low head position elevates IOP of the dependent eyes of medically treated OAG patients compared with neutral head position in the lateral decubitus posture. Adjustment of the height of a pillow may help mitigate IOP elevations resulting from lying on the side with a low or no pillow in glaucoma patients. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Tono-pen measurement of intraocular pressure under topical anaesthesia in full term normal newborns Running title:Intraocular pressure in newborns

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    Sagili Chandrasekhara Reddy

    2014-02-01

    Full Text Available AIM: Tono-pen measurement of intraocular pressure (IOP under topical anaesthesia in full term normal newborns.METHODS: The IOP measurements were taken using Tono-pen XL tonometer under topical anaesthesia in 150 newborns (300 eyes within 24h after birth, over a period of three months, in a university hospital. Gender, gestation period, mode of delivery and birth weight of newborns were noted from medical records.RESULTS:There were 70 males and 80 females. All babies were Malays. The IOP measurements were taken between 12 and 24h after birth. The gestation period of babies ranged between 37 and 41 weeks; 118 babies were delivered by spontaneous vaginal delivery and 32 by caesarian section. The birth weight of babies ranged between 2.1 and 4.3kg. The mean IOP of 300 eyes was 15.99±2.79mmHg (range 8-22. There was no statistically significant difference of mean IOP and gender, laterality of eye, type of delivery, gestation age, or birth weight of newborns.CONCLUSION: The IOP in full term normal newborns was 16mmHg. Tono-Pen appears to be ideal instrument for taking IOP in newborns because of its small size and easy handling.

  15. Intraocular pressure measurement in cynomolgus monkeys. Tono-Pen versus manometry.

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    Peterson, J A; Kiland, J A; Croft, M A; Kaufman, P L

    1996-05-01

    In living cynomolgus monkey eyes, the authors compared manometrically set and measured intraocular pressure (IOP) with simultaneous IOP readings obtained with the Tono-Pen (TP), a handheld applanation tonometer based on the Mackay-Marg principle. In three pentobarbital-anesthetized cynomolgus monkeys, IOP was set and measured manometrically after anterior chamber cannulation through the peripheral cornea with a 26-gauge needle connected to a vertically adjustable reservoir and a pressure transducer. Intraocular pressure was raised in approximately 5 mm Hg steps from 5 mm Hg to 60 mm Hg and then lowered in 5 mm Hg steps to 5 mm Hg, with TP measurements taken at each increment and decrement in open and stopcock modes. Linear regression analysis of TP on manometric readings for grouped data from all six eyes, with each data point representing the average of all the TP readings from one eye at each manometric pressure setting, showed a slope 0.692 +/- 0.016 and 0.683 +/- 0.023 (both significantly different from 1; P < 0.001), intercept 1.21 +/- 0.60 and 1.64 +/- 0.82 mm Hg (both significantly different from 0.0, P < 0.05), and correlation coefficient 0.981 and 0.96 in open stopcock and closed stopcock mode, respectively. There were no striking differences when the data were analyzed for individual eyes or animals, for open versus closed stopcock manometry, or for increasing versus decreasing manometric IOP. The TP provides reproducible measurements of IOP in cynomolgus monkeys, with measurement accuracy dependent on the generation of an appropriate calibration curve.

  16. Changes in day 1 post-operative intraocular pressure following sutureless 23-gauge and conventional 20-gauge pars plana vitrectomy.

    Science.gov (United States)

    Gosse, Emily; Newsom, Richard; Hall, Peter; Lochhead, Jonathan

    2013-01-01

    The benefits associated with transconjunctival sutureless vitrectomy techniques are continuing to be defined. The purpose of this study was to compare the incidence of extreme changes in day 1 intraocular pressure (IOP) following 23-gauge sutureless vitrectomy compared with conventional 20-gauge vitrectomy. Fifty consecutive 23-gauge and 50 consecutive 20-gauge cases were included; eyes with a history of previous vitreoretinal surgery were excluded. 23-gauge surgery was completed with passive fluid air exchange where no long acting tamponade was indicated. The surgery remained sutureless unless a leak was visible at the end of the procedure. Data were collected by retrospective case note review. Statistical analysis was carried out using Fisher's exact and chi-square tests. Twenty-two percent (11/50) of 23-gauge vitrectomies required suturing of one or more ports. On the first post-operative day hypotony (IOPgauge groups. Raised pressure (IOP>21mmHg) occurred in 30% (15/50) of eyes in the 20-gauge group and 8% (4/50) of eyes in the 23-gauge group; IOP>30mmHg only occurred in the 20-gauge group (3/50). Fluid air exchange following 23-gauge vitrectomy is associated with very low risk of day 1 hypotony. This predominantly sutureless technique appears to reduce the incidence and magnitude of early post-operative IOP elevation compared with conventional 20-gauge vitrectomy.

  17. Effects of tramadol and acepromazine on intraocular pressure and pupil diameter in young healthy cats

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    Deise Cristine Schroder

    2018-03-01

    Full Text Available ABSTRACT: This study aimed to investigate the effects of the systemic administration of acepromazine, tramadol and the association of both on intraocular pressure (IOP and pupil diameter (PD in young healthy cats. Cats were randomly allocated into three groups (n=10/each and intramuscular acepromazine (AG, tramadol (TG or acepromazine combined with tramadol (ATG were injected. PD (electronic caliper and IOP (applanation tonometry were assessed before (baseline and following 15, 30, 60, and 120 minutes of treatments. It was verified that in AG, PD decreased significantly from time point 30 to 120 (P=0.002, but such reduction did not differ significantly from baseline (P=0.89. In TG, PD increased significantly from the first 15 minutes, until the last time point of evaluation (P0.05. It can be concluded that tramadol alone or in association with acepromazine produced significant mydriasis for up to 120 minutes, without changing IOP values in normal cats. Results of this study suggested that tramadol alone or in association with acepromazine caused significant mydriasis and did not change IOP values in normal cats. Therefore, it may be considered a satisfactory pre-anesthetic combination for ophthalmic surgery in cats. However, further studies are warranted on the use of such protocols in cats with ophthalmic diseases undergoing ocular or intraocular surgery.

  18. Perioperative medications for preventing temporarily increased intraocular pressure after laser trabeculoplasty.

    Science.gov (United States)

    Zhang, Linda; Weizer, Jennifer S; Musch, David C

    2017-02-23

    Glaucoma is the international leading cause of irreversible blindness. Intraocular pressure (IOP) is the only currently known modifiable risk factor; it can be reduced by medications, incisional surgery, or laser trabeculoplasty (LTP). LTP reduces IOP by 25% to 30% from baseline, but early acute IOP elevation after LTP is a common adverse effect. Most of these IOP elevations are transient, but temporarily elevated IOP may cause further optic nerve damage, worsening of glaucoma requiring additional therapy, and permanent vision loss. Antihypertensive prophylaxis with medications such as acetazolamide, apraclonidine, brimonidine, dipivefrin, pilocarpine, and timolol have been recommended to blunt and treat the postoperative IOP spike and associated pain and discomfort. Conversely, other researchers have observed that early postoperative IOP rise happens regardless of whether people receive perioperative glaucoma medications. It is unclear whether perioperative administration of antiglaucoma medications may be helpful in preventing or reducing the occurrence of postoperative IOP elevation. To assess the effectiveness of medications administered perioperatively to prevent temporarily increased intraocular pressure (IOP) after laser trabeculoplasty (LTP) in people with open-angle glaucoma (OAG). We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) (2016, Issue 11), MEDLINE Ovid (1946 to 18 November 2016), Embase.com (1947 to 18 November 2016), PubMed (1948 to 18 November 2016), LILACS (Latin American and Caribbean Health Sciences Literature Database) (1982 to 18 November 2016), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com); last searched 17 September 2013, ClinicalTrials.gov (www.clinicaltrials.gov); searched 18 November 2016 and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en); searched 18 November 2016. We did not use any date or language restrictions. We included

  19. Influence of Corneal Opacity on Intraocular Pressure Assessment in Patients with Lysosomal Storage Diseases.

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    Joanna Wasielica-Poslednik

    Full Text Available To investigate an influence of mucopolysaccharidosis (MPS- and Morbus Fabry-associated corneal opacities on intraocular pressure (IOP measurements and to evaluate the concordance of the different tonometry methods.25 MPS patients with or without corneal clouding, 25 Fabry patients with cornea verticillata ≥ grade 2 and 25 healthy age matched controls were prospectively included into this study. Outcome measures: Goldmann applanation tonometry (GAT; palpatory assessment of IOP; Goldmann-correlated intraocular pressure (IOPg, corneal-compensated intraocular pressure (IOPcc, corneal resistance factor (CRF and corneal hysteresis (CH assessed by Ocular Response Analyzer (ORA; central corneal thickness (CCT and density assessed with Pentacam. Statistical analysis was performed using linear mixed effect models and Spearman correlation coefficients. The concordance between tonometry methods was assessed using Bland-Altman analysis.There was no relevant difference between study groups regarding median GAT, IOPg, IOPcc and CCT measurements. The limits of agreement between GAT and IOPcc/IOPg/palpatory IOP in MPS were: [-11.7 to 12.1mmHg], [-8.6 to 15.5 mmHg] and [- 5.4 to 10.1 mmHg] respectively. Limits of agreement were less wide in healthy subjects and Fabry patients. Palpatory IOP was higher in MPS than in healthy controls and Fabry patients. Corneal opacity correlated more strongly with GAT, IOPg, CH, CRF, CCT and corneal density in MPS (r = 0.4, 0.5, 0.5, 0.7, 0.6, 0.6 respectively than in Fabry patients (r = 0.3, 0.2, -0.03, 0.1, 0.3, -0.2 respectively. In contrast, IOPcc revealed less correlation with corneal opacity than GAT in MPS (r = 0.2 vs. 0.4.ORA and GAT render less comparable IOP-values in patients suffering from MPS-associated corneal opacity in comparison to Fabry and healthy controls. The IOP seems to be overestimated in opaque MPS-affected corneas. GAT, IOPg and biomechanical parameters of the cornea correlate more strongly with the

  20. Intermediate-term and long-term outcome of piggyback drainage: connecting glaucoma drainage device to a device in-situ for improved intraocular pressure control.

    Science.gov (United States)

    Dervan, Edward; Lee, Edward; Giubilato, Antonio; Khanam, Tina; Maghsoudlou, Panayiotis; Morgan, William H

    2017-11-01

    This study provides results of a treatment option for patients with failed primary glaucoma drainage device. The study aimed to describe and evaluate the long-term intraocular pressure control and complications of a new technique joining a second glaucoma drainage device directly to an existing glaucoma drainage device termed 'piggyback drainage'. This is a retrospective, interventional cohort study. Eighteen eyes of 17 patients who underwent piggyback drainage between 2004 and 2013 inclusive have been studied. All patients had prior glaucoma drainage device with uncontrolled intraocular pressure. The piggyback technique involved suturing a Baerveldt (250 or 350 mm) or Molteno3 glaucoma drainage device to an unused scleral quadrant and connecting the silicone tube to the primary plate bleb. Failure of intraocular pressure control defined as an intraocular pressure greater than 21 mmHg on maximal therapy on two separate occasions or further intervention to control intraocular pressure. The intraocular pressure was controlled in seven eyes (39%) at last follow-up with a mean follow-up time of 74.2 months. The mean preoperative intraocular pressure was 27.1 mmHg (95% confidence interval 23.8-30.3) compared with 18.4 mmHg (95% confidence interval 13.9-22.8) at last follow-up. The mean time to failure was 57.1 months (95% confidence interval 32.2-82), and the mean time to further surgery was 72.3 months (95% confidence interval 49.9-94.7). Lower preoperative intraocular pressure was associated with longer duration of intraocular pressure control (P = 0.048). If the intraocular pressure was controlled over 2 years, it continued to be controlled over the long term. Two eyes (11%) experienced corneal decompensation. Piggyback drainage represents a viable surgical alternative for the treatment of patients with severe glaucoma with failing primary glaucoma drainage device, particularly in those at high risk of corneal decompensation. © 2017 Royal Australian and New Zealand

  1. Noninvasive measurement of rat intraocular pressure with the Tono-Pen.

    Science.gov (United States)

    Moore, C G; Milne, S T; Morrison, J C

    1993-02-01

    The purpose of this study was to evaluate the Tono-Pen 2 tonometer for measuring intraocular pressure (IOP) in the living rat eye. One eye from each of 20 adult, anesthetized brown Norway rats (group 1) was cannulated and simultaneously connected to a syringe and a pressure transducer with a chart recorder. We increased IOP from 15 to 45 mmHg in 5-mmHg increments and obtained 15 consecutive readings (ignoring instrument-generated averages) at each pressure increment with a Tono-Pen 2 tonometer. To test the tonopen's ability to measure unknown IOP, transducer pressures were varied randomly in 20 additional animals (group 2), and tonopen readings were obtained in masked fashion. Plotting the mean tonopen readings for each animal against transducer IOP produced a regression formula of y = 4.54 + 0.79x (r = 0.98). Mean group 2 tonopen values plotted against transducer IOP yielded a regression formula of y = 4.75 + 0.78x (r = 0.94). A method comparison analysis showed that the tonopen significantly overestimates pressures at low IOP ( or = 30 mmHg). Using two-way analysis of variance, it was determined that the group 2 data did not differ significantly from the group 1 data (P > or = 0.76). Because of this consistency, we generated a correction factor with 95% prediction intervals for Tono-Pen readings. The Tono-Pen 2 can be used reliably to measure IOP in the normal rat eye.

  2. Effect of altered eating habits and periods during Ramadan fasting on intraocular pressure, tear secretion, corneal and anterior chamber parameters

    NARCIS (Netherlands)

    Kerimoglu, H.; Ozturk, B.; Gunduz, K.; Bozkurt, B.; Kamis, U.; Okka, M.

    Purpose To determine whether altered eating habits and periods, especially the pre-dawn meal, during Ramadan fasting have any significant effect on intraocular pressure (IOP), tear secretion, corneal and anterior chamber parameters. Methods IOP, basal tear secretion (BTS), reflex tear secretion

  3. Accuracy of intraocular pressure by Tono-Pen XL over amniotic membrane patching in rabbits.

    Science.gov (United States)

    Kobayashi, Akira; Yoshita, Tsuyoshi; Shirao, Yutaka

    2003-04-01

    To report an accuracy of intraocular pressure (IOP) by Tono-Pen XL over amniotic membrane patching in rabbits. Experimental study. Seven male albino rabbits were used in this study. After general anesthesia, IOP was measured in both eyes using the Tono-Pen without amniotic membrane. A single layer amniotic membrane was then immediately placed over the rabbit eye, and the IOP measurement was repeated. The average IOP without amniotic membrane was 5.8 +/- 0.6 mm Hg (mean +/- SD). The average IOP through amniotic membrane was 6.0 +/- 0.4 mm Hg (mean +/- SD). There was no statistical difference in IOP measured on corneas with or without the amniotic membrane (P =.34). The accuracy of IOP measurement by Tono-Pen XL over a single layer of amniotic membrane patching was demonstrated using rabbit eyes. Further studies in human eyes may verify our findings in actual clinical settings.

  4. Respiratory complications associated with ketamine anesthesia for ophthalmic procedures following intraocular pressure measurement in children

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    Lei Wu

    2014-01-01

    Full Text Available Background: We compared respiratory complications (RCs in children who received intramuscular (IM versus intravenous (IV or no ketamine for intraocular pressure (IOP measurement to test our observation that IM ketamine is associated with higher incidence of RCs. Materials and Methods: We analyzed 149 eye examinations under anesthesia with ketamine in 27 patients and 263 non-ketamine examinations under anesthesia in 81 patients using a mixed effects logistic regression model. Results: IM ketamine was strongly associated with increased odds of RCs compared to no ketamine (odds ratio (OR: 20.23, P < 0.0001 and to IV ketamine (OR: 6.78, P = 0.02, as were higher American Society of Anesthesiologists (ASA classification (OR: 2.60, P = 0.04, and the use of volatile agents (OR: 3.32, P = 0.02. Conclusion: Further studies should be conducted to confirm our observation of increased RCs with IM ketamine.

  5. The Effect of Intraocular Pressure on the Outcome of Myopic Photorefractive Keratectomy: A Numerical Approach

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    Elena Lanchares

    2010-01-01

    Full Text Available Photorefractive Keratectomy (PRK is a surgical procedure widely performed to correct myopia. In this work, the effect of the intraocular pressure (IOP on the refractive correction achieved by the PRK surgery was analyzed using a numerical model. Simulations of PRK surgery at 10, 15 and 21 mmHg of IOP were performed and the post-surgical diopters were estimated. For low and medium values of IOP (10 and 15 mmHg, the computed results were close to those used by clinicians based on experience and defined without considering the IOP, while an undercorrection was predicted for the highest value of IOP (21 mmHg. From these results, we suggest that IOP should be considered in the determination of the depth of ablation, in addition to other factors such as the level of myopia or the corneal central thickness.

  6. A longitudinal study of age-related changes in intraocular pressure: the Kangbuk Samsung Health Study.

    Science.gov (United States)

    Zhao, Di; Kim, Myung Hun; Pastor-Barriuso, Roberto; Chang, Yoosoo; Ryu, Seungho; Zhang, Yiyi; Rampal, Sanjay; Shin, Hocheol; Kim, Joon Mo; Friedman, David S; Guallar, Eliseo; Cho, Juhee

    2014-09-02

    To examine the longitudinal association between age and intraocular pressure (IOP) in a large sample of Korean men and women. We conducted a prospective cohort study of 274,064 young and middle-aged Korean adults with normal fundoscopic findings, following them from January 1, 2002, to February 28, 2010. Health exams were scheduled annually or biennially. At each visit, IOP was measured in both eyes using automated noncontact tonometers. The longitudinal change in IOP with age was evaluated using three-level mixed models for longitudinal paired-eye data, accounting for correlations between paired eyes and repeated measurements over time. In fully adjusted models, the average longitudinal change in IOP per 1-year increase in age was -0.065 mm Hg (95% confidence interval [CI] -0.068 to -0.063), with marked sex differences (P < 0.001). In men, the average annual IOP change was -0.093 mm Hg (95% CI -0.096 to -0.091) throughout follow-up. In women, the average annual IOP change was -0.006 mm Hg (95% CI -0.010 to -0.003), with a relatively flat association in the age range of 30 to 59 years and more marked annual decreases at younger and older ages. Intraocular pressure was inversely associated with age in a large cohort of Korean adults attending health-screening visits. For men, this inverse association was observed throughout the entire age range, while for women it was evident only in younger (<30 years of age) and older (≥60 years of age) women, with no association in women aged 30 to 59. Further research is needed to better understand the underlying mechanisms and to reconsider cutoffs for defining high IOP by age and sex groups in Asian populations. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

  7. A Longitudinal Study of Association between Adiposity Markers and Intraocular Pressure: The Kangbuk Samsung Health Study.

    Science.gov (United States)

    Zhao, Di; Kim, Myung Hun; Pastor-Barriuso, Roberto; Chang, Yoosoo; Ryu, Seungho; Zhang, Yiyi; Rampal, Sanjay; Shin, Hocheol; Kim, Joon Mo; Friedman, David S; Guallar, Eliseo; Cho, Juhee

    2016-01-01

    Intraocular pressure (IOP) reduction or stabilization is the only proven method for glaucoma management. Identifying risk factors for IOP is crucial to understand the pathophysiology of glaucoma. To examine the associations of change in body mass index (BMI), waist circumference, and percent fat mass with change in intraocular pressure (IOP) in a large sample of Korean adults. Cohort study of 274,064 young and middle age Korean adults with normal fundoscopic findings who attended annual or biennial health exams from January 1, 2002 to Feb 28, 2010 (577,981 screening visits). BMI, waist circumference, and percent fat mass. At each visit, IOP was measured in both eyes with automated noncontact tonometers. In multivariable-adjusted models, the average increase in IOP (95% confidence intervals) over time per interquartile increase in BMI (1.26 kg/m2), waist circumference (6.20 cm), and percent fat mass (3.40%) were 0.18 mmHg (0.17 to 0.19), 0.27 mmHg (0.26 to 0.29), and 0.10 mmHg (0.09 to 0.11), respectively (all P < 0.001). The association was stronger in men compared to women (P < 0.001) and it was only slightly attenuated after including diabetes and hypertension as potential mediators in the model. Increases in adiposity were significantly associated with an increase in IOP in a large cohort of Korean adults attending health screening visits, an association that was stronger for central obesity. Further research is needed to understand better the underlying mechanisms of this association, and to establish the role of weight gain in increasing IOP and the risk of glaucoma and its complications.

  8. Tear production, intraocular pressure and conjunctival bacterial flora in selected captive wild ruminants.

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    Kvapil, Pavel; Pirš, Tina; Slavec, Brigita; Luštrik, Roman; Zemljič, Tadej; Bártová, Eva; Stranjac, Bojana; Kastelic, Marjan

    2018-01-01

    Evaluation of tear production (Schirmer's tear test, STT) and measurement of intraocular pressure (IOP) were performed in a population of captive wild ungulates in a Slovenian ZOO during routine annual health check. In total, 10 fallow deer (Dama dama), 25 mouflons (Ovis aries musimon), 20 alpine ibexes (Capra ibex), and three alpine chamois (Rupicapra rupicapra) were included in the study. Tear production was performed by Schirmer's tear test, IOP was measured with an applanation tonometer, and ophthalmological examination was conducted with slit-lamp biomicroscopy and indirect ophthalmoscopy. Conjunctival swabs were taken and submitted for aerobic bacteriology and for detection of Chlamydia spp. and Mycoplasma spp. tested by PCR. Average tear production (in mm/min) was 17.8 ± 3.16 for fallow deer, 17.9 ± 3.87 for mouflons, and 11.7 ± 3.87 for ibexes. Mean intraocular pressure (IOP, in mm Hg) was 14.1 ± 2.48 for fallow deer, 14.9 ± 2.20 for mouflons, and 13.1 ± 2.43 for ibexes. For chamois, average tear production and IOP were 14.5 ± 3.0 and 10.2 ± 2.5, respectively; this is the first record of STT I and IOP in chamois. Bacteriological swabs were positive for bacteria in 100% of the fallow deer, 56% of mouflons, 35% of ibexes, and 100% of chamois. Gram-positive bacteria were predominant. Moraxella spp., Chlamydia spp., and Mycoplasma spp. were not detected. The reported values were obtained in animals under manual restraint only to be applicative in similar conditions. © 2017 American College of Veterinary Ophthalmologists.

  9. A correction formula for the real intraocular pressure after LASIK for the correction of myopic astigmatism.

    Science.gov (United States)

    Kohlhaas, Markus; Spoerl, Eberhard; Boehm, Andreas G; Pollack, Katharina

    2006-03-01

    To create a correction formula to determine the real intraocular pressure (IOP) after LASIK considering the altered corneal thickness, corneal curvature, and corneal stability. This prospective clinical trial comprised 101 eyes of 59 patients (34 women and 25 men) that underwent LASIK with a mean preoperative spherical equivalent refraction of -6.3 +/- 2.17 diopters (D) (-3.0 to -11.5 D). Mean patient age was 32 +/- 9 years. Preoperatively and 6 months postoperatively, IOP (by Goldmann applanation tonometry), keratometry (by topography), and central corneal thickness (CCT) (by ultrasound pachymetry) were evaluated. These parameters were measured in all patients between 8 and 11 o'clock in the morning. Due to the LASIK procedure, IOP was reduced from 16.5 +/- 2.1 mmHg (range: 12 to 22 mmHg) to 12.9 +/- 1.9 mmHg (range: 8 to 16 mmHg). Multiple linear regression analysis of the IOP values before and after LASIK showed a significant correlation between the measured IOP and CCT and keratometry values (R2=0.631; P<.001). After LASIK, the biomechanical bending strength of the cornea is reduced by the cut so that the measured IOP must be additionally corrected by 0.75 mmHg. An equation containing all three changes is given: IOP (real) = IOP (measured) + (540-CCT)/71 + (43-K-value)/2.7 + 0.75 mmHg. Intraocular pressure measurements after LASIK for the correction of myopia are inaccurate as a consequence of changes in CCT, corneal curvature, and corneal flap stability. After LASIK, the measured IOP should be corrected to avoid false low IOP applanation readings.

  10. A Longitudinal Study of Association between Adiposity Markers and Intraocular Pressure: The Kangbuk Samsung Health Study.

    Directory of Open Access Journals (Sweden)

    Di Zhao

    Full Text Available Intraocular pressure (IOP reduction or stabilization is the only proven method for glaucoma management. Identifying risk factors for IOP is crucial to understand the pathophysiology of glaucoma.To examine the associations of change in body mass index (BMI, waist circumference, and percent fat mass with change in intraocular pressure (IOP in a large sample of Korean adults.Cohort study of 274,064 young and middle age Korean adults with normal fundoscopic findings who attended annual or biennial health exams from January 1, 2002 to Feb 28, 2010 (577,981 screening visits.BMI, waist circumference, and percent fat mass.At each visit, IOP was measured in both eyes with automated noncontact tonometers.In multivariable-adjusted models, the average increase in IOP (95% confidence intervals over time per interquartile increase in BMI (1.26 kg/m2, waist circumference (6.20 cm, and percent fat mass (3.40% were 0.18 mmHg (0.17 to 0.19, 0.27 mmHg (0.26 to 0.29, and 0.10 mmHg (0.09 to 0.11, respectively (all P < 0.001. The association was stronger in men compared to women (P < 0.001 and it was only slightly attenuated after including diabetes and hypertension as potential mediators in the model.Increases in adiposity were significantly associated with an increase in IOP in a large cohort of Korean adults attending health screening visits, an association that was stronger for central obesity. Further research is needed to understand better the underlying mechanisms of this association, and to establish the role of weight gain in increasing IOP and the risk of glaucoma and its complications.

  11. Influence of Pachymetry and Intraocular Pressure on Dynamic Corneal Response Parameters in Healthy Patients.

    Science.gov (United States)

    Vinciguerra, Riccardo; Elsheikh, Ahmed; Roberts, Cynthia J; Ambrósio, Renato; Kang, David Sung Yong; Lopes, Bernardo T; Morenghi, Emanuela; Azzolini, Claudio; Vinciguerra, Paolo

    2016-08-01

    To evaluate the influence of pachymetry, age, and intraocular pressure in normal patients and to provide normative values for all dynamic corneal response parameters (DCRs) provided by dynamic Scheimpflug analysis. Seven hundred five healthy patients were included in this multicenter retrospective study. The biomechanical response data were analyzed to obtain normative values with their dependence on corrected and clinically validated intraocular pressure estimates developed using the finite element method (bIOP), central corneal thickness (CCT), and age, and to evaluate the influence of bIOP, CCT, and age. The results showed that all DCRs were correlated with bIOP except deflection amplitude (DefA) ratio, highest concavity (HC) radius, and inverse concave radius. The analysis of the relationship of DCRs with CCT indicated that HC radius, inverse concave radius, deformation amplitude (DA) ratio, and DefA ratio were correlated with CCT (rho values of 0.343, -0.407, -0.444, and -0.406, respectively). The age group subanalysis revealed that primarily whole eye movement followed by DA ratio and inverse concave radius were the parameters that were most influenced by age. Finally, custom software was created to compare normative values to imported examinations. HC radius, inverse concave radius, DA ratio, and DefA ratio were shown to be suitable parameters to evaluate in vivo corneal biomechanics due to their independence from IOP and their correlation with pachymetry and age. The creation of normative values allows the interpretation of an abnormal examination without the need to match every case with another normal patient matched for CCT and IOP. [J Refract Surg. 2016;32(8):550-561.]. © 2016 Vinciguerra, Elsheikh, Roberts, et al.: licensee SLACK Incorporated.

  12. Effects of puff times on intraocular pressure agreement between non-contact and Goldmann applanation tonometers

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    Ibrahim Toprak

    2014-07-01

    Full Text Available AIM: To compare intraocular pressure(IOPvalues obtained from two different puff modes of Canon TX-F non-contact tonometer(NCTand Goldmann applanation tonometer(GATin patients with primary open angle glaucoma(POAG. METHODS: The study group comprised 55 right eyes of 55 patients with a confirmed diagnosis of POAG, which were under treatment. All patients underwent detailed ophthalmological examinations, optical coherence tomography imaging and automated perimetry. Intraocular pressure measurements were performed using 1-puff mode of NCT(NCT1, 3-puffs mode of NCT(NCT3and GAT with 5 minutes intervals in order. RESULTS: Fifty-five eyes of 55 patients with POAG(mean age of 64.1±8.1 yearswere enrolled into the study. NCT1 and NCT3 gave similar IOP values when compared with GAT measurements(14.22±3.42, 14.28±3.29, 14.66±3.49mmHg respectively, P=0.291. Intertonometer agreement was assessed using the Bland-Altman method. The 95% limits of agreement(LoAfor NCT1-GAT, NCT3-GAT and NCT1-NCT3 comparisons were -4.9 to +4.4mmHg, -4.1 to +3.4mmHg, and -3.4 to +3.3mmHg respectively.CONCLUSION: Although IOP measurements obtained from two puff modes of NCT and GAT showed similar values, wide range of LoA might restrict use of NCT1, NCT3 and GAT interchangeably in POAG patients.

  13. The effect of laryngeal mask airway insertion on intraocular pressure measurement in children receiving general anesthesia.

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    Watts, Patrick; Lim, May Kim; Gandhewar, Ravikiran; Mukherjee, Aychut; Wintle, Richard; Armstrong, Trevor; Zatman, Tahsin; Jones, Rhys; Al Madfai, Hasan

    2007-10-01

    To study changes in intraocular pressure (IOP) in children while under general anesthesia before and after laryngeal mask airway (LMA) insertion. Prospective, comparative study. IOP was measured in children after induction and one minute after LMA insertion. Children younger than 16 years who were scheduled to undergo elective ophthalmic surgery while receiving a general anesthetic were included. Children with a history of glaucoma or previous intraocular surgery were excluded. Data were collected on the age of the child, IOP, heart rate (HR), end tidal CO2, and blood pressure (BP) before and after LMA insertion. Sixty-six children with a mean age of 5.5 +/- 3.6 years (range, four months to 16 years) were included in the study. The mean IOP was 13.6 +/- 3.9 mm Hg and 13.6 +/- 3.6 mm Hg in right and left eyes, respectively, before LMA insertion and 15.5 +/- 3.8 mm Hg and 15.2 +/- 3.8 mm Hg in right and left eyes, respectively, after LMA insertion (P = .001). A decrease in BP was significantly associated with an increase in IOP (P = .008), and the interaction between the change in the BP, HR, and CO2 affected the change in IOP measured after insertion of the LMA (P = .04). There was no correlation between the age of the child and the change in IOP measured after insertion of the LMA. In our study, a small but significantly higher IOP was found after LMA insertion than before. It is recommended that the measurement of IOP in children receiving a general anesthetic is carried out before the insertion of the LMA.

  14. [Tono-pen versus manometer. Comparative measurements of intraocular pressure in human cadaver eyes].

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    Hessemer, V; Rössler, R; Jacobi, K W

    1989-07-01

    A new hand-held tonometer, the Tono-Pen (TP), was compared with a Statham membrane manometer (MAN). The TP is a pen-sized Mackay-Marg tonometer with electronic signal analysis and digital pressure display. Comparative measurements of intra-ocular pressure (IOP) were performed on six cadavers (12 eyes in situ), 3-6 hours after death. The IOP was changed in 5 to 10 mm Hg steps in a range between 0 and 60 mm Hg by an infusion system. As compared to the manometrically determined IOP, the TP gave small overestimation of IOP below 17 mm Hg and a small underestimation above 17 mm Hg (maximum deviation 2.5 mm Hg). The mean values of 29.9 (TP) and 30.4 mm Hg (MAN) were not significantly different (p greater than 0.05, analysis of variance). The correlation coefficient was 0.99. The relationship between TP (y axis) and MAN (x axis) pressure readings is characterized exactly by a slightly curvilinear graph (y = 0.82x + 0.0002x2 + 2.52; mm Hg). This may be approximated by a regression line with a slope of 0.94, a y intercept of 1.46 mm Hg and a standard deviation of the TP readings in relation to the regression line of 2.36 mm Hg. In conclusion, the good agreement between TP and MAN pressure readings is superior to the recently described agreement between TP and Goldmann tonometer readings.

  15. Relationship between hematocrit levels and intraocular pressure in men and women: A population-based cross-sectional study.

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    Cohen, Eytan; Kramer, Michal; Shochat, Tzippy; Goldberg, Elad; Krause, Ilan

    2017-10-01

    To assess a possible relationship between hematocrit level and intraocular pressure (IOP) in both men and women.Data were collected from medical records of individuals examined at a screening center in Israel between the years 2000 and 2013. Hematocrit levels were categorized as low, normal, and high and by sex; IOP values were categorized as hematocrit for men was 42% to 52% and 37% to 47% for women. In men, mean [95% confidence interval CI)] IOP values by hematocrit level were as follows: below-normal hematocrit, 13.3 mmHg (13.2-13.3), normal hematocrit, 13.5 mmHg (13.4-13.5), above-normal hematocrit, 14.3 mmHg (13.5-15.2) (P hematocrit were found to have a significantly lower odds ratio (95% CI) of having IOP ≥18 mmHg than men with normal hematocrit: nonadjusted model, 0.761 (0.631-0.919); adjusted model, 0.771 (0.638-0.932) (P hematocrit level may also contribute to an elevated IOP in men in addition to the classic risk factors.

  16. ATP-sensitive potassium (KATP channel openers diazoxide and nicorandil lower intraocular pressure by activating the Erk1/2 signaling pathway.

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    Uttio Roy Chowdhury

    Full Text Available Elevated intraocular pressure is the most prevalent and only treatable risk factor for glaucoma, a degenerative disease of the optic nerve. While treatment options to slow disease progression are available, all current therapeutic and surgical treatments have unwanted side effects or limited efficacy, resulting in the need to identify new options. Previous reports from our laboratory have established a novel ocular hypotensive effect of ATP-sensitive potassium channel (KATP openers including diazoxide (DZ and nicorandil (NCD. In the current study, we evaluated the role of Erk1/2 signaling pathway in KATP channel opener mediated reduction of intraocular pressure (IOP. Western blot analysis of DZ and NCD treated primary normal trabecular meshwork (NTM cells, human TM (isolated from perfusion cultures of human anterior segments and mouse eyes showed increased phosphorylation of Erk1/2 when compared to vehicle treated controls. DZ and NCD mediated pressure reduction (p0.1. Histologic evaluation of transmission electron micrographs from DZ + U0126 and NCD + U0126 treated eyes revealed no observable morphological changes in the ultrastructure of the conventional outflow pathway. Taken together, the results indicate that the Erk1/2 pathway is necessary for IOP reduction by KATP channel openers DZ and NCD.

  17. Can we trust intraocular pressure measurements in eyes with intracameral air?

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    Jóhannesson, Gauti; Lindén, Christina; Eklund, Anders; Behndig, Anders; Hallberg, Per

    2014-10-01

    To evaluate the effect of intracameral air on intraocular pressure (IOP) measurements using Goldmann applanation tonometry (GAT) and applanation resonance tonometry (ART) in an in-vitro porcine eye model. IOP was measured on thirteen freshly enucleated eyes at three reference pressures: 20, 30, and 40 mmHg. Six measurements/method were performed in a standardized order with GAT and ART respectively. Air was injected intracamerally in the same manner as during Descemet's stripping endothelial keratoplasty (DSEK) and Descemet's membrane endothelial keratoplasty (DMEK), and the measurements were repeated. Measured IOP increased significantly for both tonometry methods after air injection: 0.7 ± 2.1 mmHg for GAT and 10.6 ± 4.9 mmHg for ART. This difference was significant at each reference pressure for ART but not for GAT. Although slightly affected, this study suggests that we can trust GAT IOP-measurements in eyes with intracameral air, such as after DSEK/DMEK operations. Ultrasound-based methods such as ART should not be used.

  18. Intraocular pressure control of a novel glaucoma drainage device - in vitro and in vivo studies

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    Li-Jun Cui

    2017-09-01

    Full Text Available AIM: To evaluate the intraocular pressure (IOP control of an artificial trabeculum drainage system (ATDS, a newly designed glaucoma drainage device, and postoperative complications in normal rabbit eyes. METHODS: Pressure drops in air and fluid of 30 ATDS were measured after being connected to a closed manometric system. Twenty of them were then chosen and implanted randomly into the eyes of 20 rabbits. Postoperative slit-lamp, gonioscopic examination and IOP measurements were recorded periodically. Ultrasound biomicroscopy and B-scan ultrasonography were also used to observe the complications. Eyes were enucleated on day 60. RESULTS: Pressure drops of 4.6-9.4 mm Hg were obtained at physiological aqueous flow rates in the tests in vitro. The average postoperative IOP of the experimental eyes (11.6-12.8 mm Hg was lower than the controls significantly (P<0.05 at each time point. Complications of hemorrhage (n=1, cellulosic exudation (two cases and local iris congestion (two cases were observed. The lumina of the devices were devoid of obstructions in all specimens examined and a thin fibrous capsule was found around the endplate. CONCLUSION: ATDS reduce IOP effectively. However, further studies on the structure are needed to reduce complications.

  19. Effect of phacoemulsification on intraocular pressure in patients with primary open angle glaucoma and pseudoexfoliation glaucoma

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    Jesus Jimenez-Roman

    2017-09-01

    Full Text Available AIM: To compare the effect of phacoemulsification on intraocular pressure (IOP in patients with primary open angle glaucoma (POAG and pseudoexfoliation glaucoma (PXG. METHODS: A retrospective comparative case series conducted at the Glaucoma Department at the Association to Prevent Blindness in Mexico. The study enrolled consecutive patients having phacoemulsification with intraocular lens (IOL implantation and a diagnosis of POAG or PXG. Data about IOP values and number of glaucoma medications used was collected at baseline, 1, 3, 6 and 12mo postoperatively. RESULTS: The study enrolled 88 patients (88 eyes. After phacoemulsification, there was a statistically significant reduction in IOP values and glaucoma medications use compared to baseline in both POAG and PXG patients (P<0.001. In the POAG group, a 20% decrease in IOP values was evidenced, and a 56.5% reduction in the number of medications used at the one-year follow-up. The PXG group showed a 20.39%, and a 34.46% decrease in IOP and number of medications used, respectively. A significant difference in the mean ΔIOP (postoperative changes in IOP was evidenced between groups (P=0.005. The reduction of the postsurgical IOP mean values in both groups, the POAG group showed a greater reduction in IOP values compared to the PXG group. CONCLUSION: In both types of glaucoma, phacoemulsification cataract surgery can result in a significant IOP reduction (20% over a 12mo follow-up period. The number of medications used is also significantly reduced up to 12mo after surgery, especially in the PXG group.

  20. Effects of tramadol on tear production, intraocular pressure, and pupil size in dogs: clinical study

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    Thaís Ruiz

    2015-04-01

    Full Text Available This study aimed to evaluate the effects of tramadol on tear production, intraocular pressure (IOP and pupil diameter (PD in healthy dogs. Dogs were randomly assigned to receive 4mg kg-1 (n=11 and 6mg kg-1 (n=11 of tramadol hydrochloride intramuscularly. Tear production (Schirmer tear test, STT-1, IOP (applanation tonometry and the PD (electronic pachymetry were assessed before, 30 and 60 minutes after administration of tramadol. Data were compared by analysis of variance for repeated measures (P<0.05. Parameters evaluated before, at 30 and 60min, in dogs treated with 4 and 6mg kg-1, were respectively: (STT-1 22.50±3.38, 21.14±3.94 and 21.09±2.99mm min-1; and 23.05±3.73,22.64±3.76 and 22.82±3.25mm min-1. (IOP 18.14±2.68, 17.68±2.59 and 18.23±3.84mmHg; and 19.05±2.27, 18.91±2.74 and 17.64±2.34mmHg. (PD 6.71±0.65, 7.22±1.42 and 6.90±1.39mm; and 6.25±1.08, 6.80±1.27 and 6.49±0.90mm. All parameters evaluated did not change significantly among time points and dose regimen. Based on the conditions under which the experiments were conducted, tramadol did not affect tear production, IOP and PD in dogs, and could be used as a preoperative analgesic for intraocular surgery and pain control for any cause in patients affected by uveitis, glaucoma and keratoconjunctivitis sicca

  1. 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.

  2. Implantation and testing of a novel episcleral pressure transducer: A new approach to telemetric intraocular pressure monitoring.

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    Mariacher, Siegfried; Ebner, Martina; Hurst, José; Szurman, Peter; Januschowski, Kai

    2018-01-01

    Measurement of intraocular pressure (IOP) is an essential tool in monitoring glaucoma. Single IOP assessments during clinical routine examinations represent punctual values and are not able to identify IOP fluctuations and spikes. Telemetric IOP measurements are able to monitor IOP during the day and night, and are location-independent. Six telemetric episcleral IOP sensors were investigated after minimally invasive subconjunctival implantation in 6 eyes of 6 New-Zealand-White rabbits. Three of the 4 edges of the implant were fixated intrasclerally with non-absorbable sutures. The sutures were stitched into the edges of the implants' silicone rubber encasements. Telemetric IOP measurements were validated 1 week, 4 weeks, 8 weeks, 12 weeks and 30 weeks after implantation. For each validation the anterior chamber was cannulated and connected to a height-adjustable water column. Different intracameral pressure levels (10-45 mmHg) were generated by height adjustment of the water column. Measurement reliability and concordance between telemetric and intracameral IOP was validated using Bland-Altman analysis. Overall comparison (10-45 mmHg) between telemetric and intracameral pressure revealed a standard deviation of ±1.0 mmHg. A comparison of pressure values in the range between 10 and 30 mmHg revealed a standard deviation of ±0.8 mmHg. Device deficiency was related to follow-up length: 4 weeks after implantation, 3 of the 6 sensors showed malfunction, with all sensors having failed 30 weeks after implantation. The most likely reason for the sensor malfunction is the loss of hermeticity as a result of penetration of the encasement during the episcleral fixation, resulting from the lack of preformed suture holes at the implants encasement. However, no clinical signs of injury or inflammation of the conjunctiva, sclera, implantation site or any other involved structures were observed, except for an expected mild short-term irritation postoperatively. The episcleral

  3. Intraocular pressure dynamics with prostaglandin analogs: a clinical application of water-drinking test

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    Özyol P

    2016-07-01

    Full Text Available Pelin Özyol,1 Erhan Özyol,1 Ercan Baldemir2 1Ophthalmology Department, 2Biostatistics Department, Faculty of Medicine, Mugla Sitki Kocman University, Mugla, Turkey Aim: To evaluate the clinical applicability of the water-drinking test in treatment-naive primary open-angle glaucoma patients. Methods: Twenty newly diagnosed primary open-angle glaucoma patients and 20 healthy controls were enrolled in this prospective study. The water-drinking test was performed at baseline and 6 weeks and 3 months after prostaglandin analog treatment. Peak and fluctuation of intraocular pressure (IOP measurements obtained with the water-drinking test during follow-up were analyzed. Analysis of variance for repeated measures and paired and unpaired t-tests were used for statistical analysis. Results: The mean baseline IOP values in patients with primary open-angle glaucoma were 25.1±4.6 mmHg before prostaglandin analog treatment, 19.8±3.7 mmHg at week 6, and 17.9±2.2 mmHg at month 3 after treatment. The difference in mean baseline IOP of the water-drinking tests was statistically significant (P<0.001. At 6 weeks of prostaglandin analog treatment, two patients had high peak and fluctuation of IOP measurements despite a reduction in baseline IOP. After modifying treatment, patients had lower peak and fluctuation of IOP values at month 3 of the study. Conclusion: Peak and fluctuation of IOP in response to the water-drinking test were lower with prostaglandin analogs compared with before medication. The water-drinking test can represent an additional benefit in the management of glaucoma patients, especially by detecting higher peak and fluctuation of IOP values despite a reduced mean IOP. Therefore, it could be helpful as a supplementary method in monitoring IOP in the clinical practice. Keywords: glaucoma, intraocular pressure, water-drinking test, prostaglandin analog, intra­ocular pressure fluctuation

  4. Iris transillumination defect and its gene modulators do not correlate with intraocular pressure in the BXD family of mice.

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    Lu, Hong; Lu, Lu; Williams, Robert W; Jablonski, Monica M

    2016-01-01

    Intraocular pressure (IOP) is currently the only treatable phenotype associated with primary open angle glaucoma (POAG). Our group has developed the BXD murine panel for identifying genetic modulators of the various endophenotypes of glaucoma, including pigment dispersion, IOP, and retinal ganglion cell (RGC) death. The BXD family consists of the inbred progeny of crosses between the C57BL/6J (B6) strain and the glaucoma-prone DBA/2J (D2) strain that has mutations in Tyrp1 and Gpnmb. The role of these genes in the iris transillumination defect (TID) has been well documented; however, their possible roles in modulating IOP during glaucoma onset and progression are yet not well understood. We used the IOP data sets and the Eye M430v2 (Sep08) RMA Database available on GeneNetwork to determine whether mutations in Tyrp1 and Gpnmb or TIDs have a direct role in the elevation of IOP in the BXD family. We also determined whether TIDs and IOP are coregulated. As expected, Tyrp1 and Gpnmb expression levels showed a high degree of correlation with TIDs. However, there was no correlation between the expression of these genes and IOP. Moreover, unlike TIDs, IOP did not map to either the Tyrp1 or Gpnmb locus. Although the Tyrp1 and Gpnmb mutations in BXD strains are a prerequisite for the development of TID, they are not required for or associated with elevated IOP. Genetic modulators of IOP thus may be independently identified using the full array of BXD mice without concern for the presence of TIDs or mutations in Typr1 and/or Gpnmb.

  5. Porcine Model to Evaluate Real-Time Intraocular Pressure During Femtosecond Laser Cataract Surgery.

    Science.gov (United States)

    Ibarz, Marta; Hernández-Verdejo, José Luis; Bolívar, Gema; Tañá, Pedro; Rodríguez-Prats, José Luis; Teus, Miguel A

    2016-04-01

    To investigate the changes in intraocular pressure (IOP) in porcine eyes during femtosecond laser-assisted cataract surgery using a liquid-optic interface system. Femtosecond laser cataract surgery with the Catalys™ was performed on freshly enucleated porcine eyes in Oftalvist Moncloa, Madrid, Spain. Capsulorhexis and lens fragmentation were completed in all the eyes without complications. IOP was measured with a reusable blood pressure transducer connected by direct cannulation to the anterior chamber, recording data before suction (basal), at the beginning of the suction phase, every five seconds during femtosecond procedure and after the removal of the suction ring from the eye. Nine porcine eyes were used in this study. Basal IOP before suction was 5.67 ± 2.39 mmHg, rising to 20.33 ± 4.18 mmHg at the beginning of the suction phase (p < 0.001). During femtosecond procedure, pressure reached a value of 19.74 ± 4.31 mmHg, remaining stable during the entire process. The IOP recorded prior to removal of the suction ring was 21.00 ± 6.93 mmHg, returning to basal values in all the eyes after the suction ring was removed, with no statistical differences between basal and post-suction IOPs. Total femtosecond procedure time was 125.9 ±  15.9 s. Real-time IOP can be measured during surgery using a transducer connected to the anterior chamber. The results showed a significant increase in IOP during the procedure due to the pressure exerted by the suction ring but not by the effect of the femtosecond laser.

  6. Ethnic differences of intraocular pressure and central corneal thickness: the Singapore Epidemiology of Eye Diseases study.

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    Chua, Jacqueline; Tham, Yih Chung; Liao, Jiemin; Zheng, Yingfeng; Aung, Tin; Wong, Tien Yin; Cheng, Ching-Yu

    2014-10-01

    To determine the ethnic differences in the distribution of intraocular pressure (IOP) and central corneal thickness (CCT) in a multi-ethnic Asian population by self-reported ethnicity and genetic ancestry. Population-based, cross-sectional study. A total of 10 033 adults (3353 Chinese, 3280 Malays, and 3400 Indians) aged >40 years. Participants underwent standardized systemic and ocular examinations and interviewer-administered questionnaires for risk factor assessment. The IOP readings were obtained by Goldmann applanation tonometry (Haag-Streit, Konig, Switzerland) before pupil dilation. The CCT was measured with ultrasound pachymetry. Genetic ancestry was derived using principal component (PC) analysis. Regression models were used to investigate the association of IOP and CCT with potential risk factors and genetic ancestry. Intraocular pressure and CCT. After excluding participants with a history of glaucoma surgery or medication, refractive surgery, corneal edema, or corneal dystrophy, IOP and CCT readings were available for 3251 Chinese, 3232 Malays, and 3317 Indians. The mean IOP readings in the Chinese, Malay, and Indian participants were 14.3±3.1, 15.3±3.7, and 15.8±2.9 mmHg, respectively (P Chinese, 6.2% in Malays, and 4% in Indians (P Malay and Indian participants on average had 0.81 and 1.43 mmHg higher IOP levels, respectively, than Chinese (P Chinese, 540.9±33.6 μm in Malays, and 540.4±33.6 μm in Indians (P Chinese, 68.5% in Malays, and 66.2% in Indians (P Chinese have the thickest CCT but lowest IOP among the 3 major ethnic groups. In addition, there is a higher proportion of Malays with IOP ≥21 mmHg and CCT Chinese or Indians. This disparity across ethnic groups should be taken into account by future studies investigating IOP and CCT as risk factors or diagnostic tests for glaucoma in Asian populations. Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

  7. The interoccasion repeatability of intraocular pressure measurement using the Tono-Pen in a sample of school-aged children.

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    Khamees, K M; Zadnik, K

    2001-08-01

    The purpose of this study was to assess the interoccasion repeatability of the Tono-Pen XL portable applanation tonometer in school-aged children. Thirty-one normal children were recruited from The Ohio State College of Optometry Pediatric Clinic. They ranged in age from 6 to 14 years. Intraocular pressure was measured using the Tono-Pen XL in both eyes of all subjects on two different occasions within a median of 9 days. Refractive error was measured by noncycloplegic autorefraction. Data from right eyes only are presented. There was no average difference in the intraocular pressure between occasions. The 95% limits of agreement between occasions were -5.58 to 4.87 mm Hg. The Tono-Pen XL gives reasonably repeatable readings between occasions in school-aged children.

  8. The Association of Central corneal thickness with Intra-ocular Pressure and Refractive Error in a Nigerian Population

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    Eghosasere Iyamu

    2008-01-01

    Full Text Available The purpose of this study was to determine the variation of central corneal thickness (CCT with intraocular pressure (IOP and spherical equivalent refractive error. A total of thirty-nine (N=39 subjects within 20-75 years with mean age 45.2 ± 15.4 years were used for this study. The central corneal thickness was assessed with the Corneo-Gage plus ultrasonic Pachymeter, the IOP with slit-lamp mounted Goldmann applanation tonometer and refractive status by Protec 2000 autorefractor, phoropter and trial lens set. Results obtained showed that there was no linear correlation between CCT and spherical equivalent errors, although the association between them was significant (p<0.05. The linear correlation between CCT and IOP was not statistically significant. The central corneal thickness was weakly correlated with age; with increasing age the central corneal thickness decreases. Neither the central corneal thickness nor the intraocular pressure was affected by gender.

  9. Goldmann applanation tonometry error relative to true intracameral intraocular pressure in vitro and in vivo.

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    McCafferty, Sean; Levine, Jason; Schwiegerling, Jim; Enikov, Eniko T

    2017-11-25

    Goldmann applanation tonometry (GAT) error relative to intracameral intraocular pressure (IOP) has not been examined comparatively in both human cadaver eyes and in live human eyes. Futhermore, correlations to biomechanical corneal properties and positional changes have not been examined directly to intracameral IOP and GAT IOP. Intracameral IOP was measured via pressure transducer on fifty-eight (58) eyes undergoing cataract surgery and the IOP was modulated manometrically on each patient alternately to 10, 20, and 40 mmHg. IOP was measured using a Perkins tonometer in the supine position on 58 eyes and upright on a subset of 8 eyes. Twenty one (21) fresh human cadaver globes were Intracamerally IOP adjusted and measured via pressure transducer. Intracameral IOP ranged between 5 and 60 mmHg. IOP was measured in the upright position with a Goldmann Applanation Tonometer (GAT) and supine position with a Perkins tonometer. Central corneal thickness (CCT) was also measured. The Goldmann-type tonometer error measured on live human eyes was 5.2 +/-1.6 mmHg lower than intracameral IOP in the upright position and 7.9 +/- 2.3 mmHg lower in the supine position (p error (correlation coeff. = 0.18). Cadaver eye IOP measurements were 3.1+/-2.5 mmHg lower than intracameral IOP in the upright position and 5.4+/- 3.1 mmHg in the supine position (p error is increased an additional 2.8 mmHg lower in the supine position. CCT appears to significantly affect the error by up to 4 mmHg over the sample size.

  10. Effects of corn silk aqueous extract on intraocular pressure of ocular hypertensive human subjects

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    G.O. George

    2013-01-01

    Full Text Available Stigma/style of Zea mays L (Corn silk has been documented to have hypotensive effect on blood pressure and to relieve oedema. However we are not aware of any literature on its hypotensive effect on intraocular pressure (IOP of humans or animals. We studied the effects of water only, masked doses of corn silk aqueous extract (60 mg/kg, 130 mg/kg, 192.5 mg/kg and 260 mg/kg body weight on the IOP and blood pressure (BP of twenty normotensives and twenty ocular hypertensive subjects. Also we compared the effects of the varied doses of corn silk aqueous extract (CSAE with masked doses (5 mg/kg and 10 mg/kg body weight of acetazolamide on IOP of ocular hypertensive subjects only. The results showed that the last three doses of CSAE lowered IOP and BP significantly (p<0.001 within eight hours of administration. The peak effect on IOP was observed after four hours while the peak effect on BP was observed after three hours of administration in the normotensives and ocular hypertensive subjects likewise the hypotensive effect was dose-dependent. The results also showed that 130 mg/kg body weight of CSAE produced the same hypotensive effect on IOP of ocular hypertensive subjects as 5 mg/kg body weight of acetazolamide. Therefore CSAE may have some IOP lowering effects that require further investigation in the management of ocular hypertension. (S Afr Optom 2013 72(3 133-143

  11. Influence of GlideScope assisted endotracheal intubation on intraocular pressure in ophthalmic patients

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    Nauman Ahmad

    2015-01-01

    Full Text Available Background: Traditional Macintoch laryngoscopy is known to cause a rise in intraocular pressure (IOP, tachycardia and hypertension. These changes are not desirable in patients with glaucoma and open globe injury. GlideScope is a video laryngoscope that functions independent of the line of sight, reduces upward lifting forces for glottic exposure and requires less cervical neck movement for intubation, making it less stimulating than Macintosh laryngoscopy. Aim: The aim was to assess the variations in IOP and hemodynamic changes after GlideScope assisted intubation. Materials and Methods: After approval of the local Institutional Research and Ethical Board and informed patient consent, 50 adult American Society of Anesthesiologist I and II patients with normal IOP were enrolled in a prospective, randomized study for ophthalmic surgery requiring tracheal intubation. In all patients, trachea was intubated using either GlideScope or Macintoch laryngoscope. IOP of nonoperated eye, heart rate and blood pressure were measured as baseline, 1 min after induction, 1 min and 5 min after tracheal intubation. Results: IOP was not significantly different between groups before and after anesthetic induction and 5 min after tracheal intubation (P = 0.217, 0.726, and 0.110 respectively. The only significant difference in IOP was at 1 min after intubation (P = 0.041. No significant difference noted between groups in mean arterial pressure (P = 0.899, 0.62, 0.47, 0.82 respectively and heart rate (P = 0.21, 0.72, 0.07, 0.29, respectively at all measurements. Conclusion: GlideScope assisted tracheal intubation shown lesser rise in IOP at 1 min after intubation in comparison to Macintoch laryngoscope, suggesting that GlideScope may be preferable to Macintosh laryngoscope.

  12. Insertion of laryngeal mask airway does not increase the intraocular pressure in children with glaucoma.

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    Bhardwaj, Neerja; Yaddanapudi, Sandhya; Singh, Swati; Pandav, Surinder S

    2011-10-01

    It is hypothesized that in children with glaucoma, the insertion of laryngeal mask airway (LMA) will cause lesser rise in intraocular pressure (IOP) than tracheal tube (TT). To compare the IOP response to LMA and TT insertion in children with glaucoma. A prospective, randomized, single-blind study was conducted in 30 glaucomatous ASA-1 children, aged 1-10 years scheduled to undergo trabeculectomy. Anesthesia was induced with halothane and maintained for 5 min with 1 MAC of halothane after administering atracurium 0.5 mg·kg(-1) following which LMA or TT was introduced. IOP was measured in both the eyes before and after insertion of airway device for 5 min. The IOP increased significantly from 27.3 ± 5.2 to 31.2 ± 5.4 mmHg (P insertion of LMA. The IOP was significantly higher in group TT compared to group LMA at 2 min (P = 0.004) and 5 min (P = 0.01) after the device insertion. The heart rate (HR) increased significantly after tracheal intubation and returned to baseline 4 min after intubation. The HR increase was significantly more in TT group compared to LMA group at all times of observation. Both systolic blood pressure (SBP; P = 0.01) and diastolic blood pressure (DBP; P = 0.02) showed an increase at 1 min in children in group TT. Insertion of LMA in glaucomatous children is not associated with an increased IOP response or cardiovascular changes. © 2011 Blackwell Publishing Ltd.

  13. Intraocular pressure reduction of fixed combination timolol maleate 0.5% and dorzolamide 2% (Cosopt) administered three times a day

    OpenAIRE

    Shemesh, Gabi; Moisseiev, Elad; Lazar, Moshe; Kurtz, Shimon

    2012-01-01

    Gabi Shemesh*, Elad Moisseiev*, Moshe Lazar1, Shimon Kurtz Department of Ophthalmology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel; Affiliated to the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel*The first two authors contributed equallyPurpose: To evaluate the safety and efficacy in intraocular pressure (IOP) reduction of increasing Cosopt dosage from twice to three times a day.Methods: The study included patients with primary open-angle glaucoma or ocular hypert...

  14. Diagnostic accuracy of intraocular pressure measurement for the detection of raised intracranial pressure: meta-analysis: a systematic review.

    Science.gov (United States)

    Yavin, Daniel; Luu, Judy; James, Matthew T; Roberts, Derek J; Sutherland, Garnette R; Jette, Nathalie; Wiebe, Samuel

    2014-09-01

    Because clinical examination and imaging may be unreliable indicators of intracranial hypertension, intraocular pressure (IOP) measurement has been proposed as a noninvasive method of diagnosis. The authors conducted a systematic review and meta-analysis to determine the correlation between IOP and intracranial pressure (ICP) and the diagnostic accuracy of IOP measurement for detection of intracranial hypertension. The authors searched bibliographic databases (Ovid MEDLINE, Ovid EMBASE, and the Cochrane Central Register of Controlled Trials) from 1950 to March 2013, references of included studies, and conference abstracts for studies comparing IOP and invasive ICP measurement. Two independent reviewers screened abstracts, reviewed full-text articles, and extracted data. Correlation coefficients, sensitivity, specificity, and positive and negative likelihood ratios were calculated using DerSimonian and Laird methods and bivariate random effects models. The I(2) statistic was used as a measure of heterogeneity. Among 355 identified citations, 12 studies that enrolled 546 patients were included in the meta-analysis. The pooled correlation coefficient between IOP and ICP was 0.44 (95% CI 0.26-0.63, I(2) = 97.7%, p intracranial hypertension were 81% (95% CI 26%-98%, I(2) = 95.2%, p intracranial hypertension. Given the significant heterogeneity between included studies, further investigation is required prior to the adoption of IOP in the evaluation of intracranial hypertension into routine practice.

  15. Association of demographic, familial, medical, and ocular factors with intraocular pressure.

    Science.gov (United States)

    Weih, L M; Mukesh, B N; McCarty, C A; Taylor, H R

    2001-06-01

    To describe the distribution and associations of demographic, familial, medical, and ocular factors with intraocular pressure (IOP). A cluster stratified random sample of urban and rural residents of Victoria, Australia, aged 40 years and older. Participants completed an interview and underwent a standardized dilated ophthalmic examination including measurement of IOP with an electronic applanation tonometer (Tono-Pen). Glaucoma status (possible, probable, definite) was determined by a consensus panel. The main outcome measure was IOP. The mean age of the 4576 participants was 59 years, 53% were women, 32% were born overseas, and 132 had open-angle glaucoma. Geometric mean (SD) IOP was 14.3 (+/-1.5) mm Hg. The relationship between IOP and nuclear sclerosis, iris color, and family history of glaucoma depended on glaucoma status. In those with glaucoma, family history of glaucoma and country of birth were significantly associated with IOP in multivariate models (model: r(2) = 0.08, P =.01). In the group without glaucoma, place of residence, use of alcohol, iris color, vitamin E intake, and spherical equivalent were associated with IOP (model: r(2) = 0.01, P =.006). In participants with glaucoma, genetic factors seem to be stronger predictors of IOP, whereas in those without glaucoma, lifestyle and physiological factors seem to play a greater role.

  16. Reliability of intraocular pressure by Tono-Pen XL over amniotic membrane patch in human.

    Science.gov (United States)

    Yoshita, Tsuyoshi; Kobayashi, Akira; Takahashi, Mami; Sugiyama, Kazuhisa

    2004-10-01

    To determine the reliability of Tono-Pen XL in measuring intraocular pressure (IOP) over the amniotic membrane patch in human eyes. Ten healthy volunteers (nine males and one female) participated in this study. After topical anesthesia, IOP was measured using the Tono-Pen XL before and after the application of a single-layer amniotic membrane patch in the right eye and double-layer amniotic membrane patch in the left eye. We found no statistical difference between the IOP measured with and without a single layer amniotic membrane (P = 0.808). Nor did we find any statistical difference between the IOP measured with and without double-layer amniotic membrane patch (P = 0.813). The average thickness of the single- and the double-layer amniotic membrane patch measured by pachymetry was 131.9 +/- 31.4 microm (mean +/- SD) and was 246.1 +/- 69.3 microm (mean +/- SD), respectively. This study showed that it is reliable to measure IOP by Tono-Pen XL over single or a double layer of amniotic membrane patch on healthy human eyes. Further studies are required to determine the accuracy of IOP measurement over amniotic membrane patch on diseased corneas.

  17. Tono-pen measurement of intraocular pressure under topical anaesthesia in full term normal newborns.

    Science.gov (United States)

    Reddy, Sagili Chandrasekhara; Alias, Rosnita

    2014-01-01

    Tono-pen measurement of intraocular pressure (IOP) under topical anaesthesia in full term normal newborns. The IOP measurements were taken using Tono-pen XL tonometer under topical anaesthesia in 150 newborns (300 eyes) within 24h after birth, over a period of three months, in a university hospital. Gender, gestation period, mode of delivery and birth weight of newborns were noted from medical records. There were 70 males and 80 females. All babies were Malays. The IOP measurements were taken between 12 and 24h after birth. The gestation period of babies ranged between 37 and 41 weeks; 118 babies were delivered by spontaneous vaginal delivery and 32 by caesarian section. The birth weight of babies ranged between 2.1 and 4.3kg. The mean IOP of 300 eyes was 15.99±2.79mmHg (range 8-22). There was no statistically significant difference of mean IOP and gender, laterality of eye, type of delivery, gestation age, or birth weight of newborns. The IOP in full term normal newborns was 16mmHg. Tono-Pen appears to be ideal instrument for taking IOP in newborns because of its small size and easy handling.

  18. Tono-Pen determination of intraocular pressure in patients with band keratopathy or glued cornea.

    Science.gov (United States)

    Azuara-Blanco, A; Bhojani, T K; Sarhan, A R; Pillai, C T; Dua, H S

    1998-06-01

    To evaluate the intraocular pressure (IOP) measurements in patients with band keratopathy or glued corneas obtained from affected and non-affected areas. 15 patients with band keratopathy or glued corneas were prospectively recruited. When both eyes were affected, only the right eye was analysed. Tono-Pen readings of IOP were obtained sequentially from the affected and non-affected corneal surface. Additionally, Goldmann applanation tonometry was attempted. Determination of IOP with the Tono-Pen was possible in all cases, while Goldmann tonometry was not performed in three patients because of severe corneal irregularities. The average of the Tono-Pen readings obtained from the affected cornea (34.8 (SD 14.0) mm Hg) was consistently and significantly higher (p < 0.001) than mean IOP obtained by the Tono-Pen from the non-affected area (14.8 (4.3) mm Hg). The average of Goldmann tonometry readings (14.4 (6.1) mm Hg) did not differ significantly from the Tono-Pen values obtained from the non-affected corneal area (p = 0.47) but was significantly lower than the Tono-Pen measurements obtained from the affected area (p < 0.001). In patients with band keratopathy or glued corneas determination of IOP by Tono-Pen tonometry varies from affected to non-affected area. The Tono-Pen overestimates the level of IOP when it is applied to areas with band keratopathy or with glue.

  19. Intraocular pressure in American Bullfrogs (Rana catesbeiana) measured with rebound and applanation tonometry.

    Science.gov (United States)

    Cannizzo, Sarah A; Lewbart, Gregory A; Westermeyer, Hans D

    2017-11-01

    To measure the intraocular pressure (IOP) in normal American Bullfrogs (Rana catesbeiana) with rebound and applanation tonometry and to create calibration curves for both tonometers to determine the actual IOP of bullfrogs. Twenty bullfrogs were evaluated with slip-lamp biomicroscopy, indirect ophthalmoscopy, rebound tonometry, and applanation tonometry. Axial globe length and corneal thickness were measured in the three largest and the three smallest frogs with ultrasonography and optical coherence tomography, respectively. Two frogs were euthanized for direct manometry. The median IOP was 4 mmHg with the rebound tonometer and 16 mmHg with the applanation tonometer. The correlation coefficient (r 2 ) between the manometry measurements and the tonometers was 0.95 and 0.91 for the rebound and applanation tonometers, respectively. The corresponding equations were y = 0.331x + 0.558 for the rebound tonometer and y = 0.675x + 1.907 for the applanation tonometer. The median axial globe length was 0.94 cm. The median corneal thickness was 0.093 mm. The rebound tonometer is the preferable tonometer for American Bullfrogs. Neither tonometer produced IOP readings that matched the manometer. The rebound tonometer was more precise and it was faster and easier to use. © 2017 American College of Veterinary Ophthalmologists.

  20. Twenty-four-Hour Measurement of Intraocular Pressure in Guinea Pigs (Cavia porcellus).

    Science.gov (United States)

    Ansari-Mood, Maneli; Mehdi-Rajaei, Seyed; Sadjadi, Reza; Selk-Ghaffari, Masoud; Williams, David L

    2016-01-01

    The objective of this study was to measure intraocular pressure (IOP) in intact, healthy guinea pigs (15 male, 15 female) every 2 h for a 24-h period. First, IOP was measured by using rebound tonometry (RBT). After a 1-min rest period, 0.5% proparacaine ophthalmic solution, a topical anesthetic, was applied to both eyes; 4 min after anesthetic instillation, IOP was measured by using applanation tonometry (APT). The IOP was lower during the light period (0700 to 1900) than during the dark phase (2000 to 0600). The lowest IOP by both RBT and APT (3.68 and 13.37 mm Hg, respectively) occurred at 0700, whereas maximal IOP occurred at 2300 for RBT (8.12 mm Hg) but at 2100 for APT (20.62 mm Hg). No significant differences in IOP between the left and right eyes or between RBT and APT were noted. In addition, daily variations in the IOP of guinea pigs seem to be independent of sex and body weight. The results of this study may be beneficial in the diagnosis and observation of glaucoma in guinea pigs.

  1. The effects of prostaglandins on the intraocular pressure of the rabbit

    Science.gov (United States)

    Beitch, Barbara R.; Eakins, K. E.

    1969-01-01

    1. The effects of intracameral injections of prostaglandins E1, E2, F1a, F2a, and A1 were studied on the intraocular pressure (IOP) of rabbits anaesthetized with urethane. 2. With the exception of prostaglandin F1a, all the prostaglandins studied were found to be capable of producing a large, sustained rise in IOP, accompanied in many cases by miosis. 3. A marked decrease in response to repeated injections was found with all the prostaglandins studied; this effect was more pronounced following a large initial response to the prostaglandin. 4. The descending order of potency in their ability to raise IOP was as follows: prostaglandin E1≈E2>F2a>A1>F1a. 5. Intracameral injections of prostaglandins E1 and E2 resulted in an increase in the protein content of the aqueous humour, which was related to the magnitude of the sustained increase in IOP. 6. Stabilization of the blood-aqueous barrier with polyphloretin phosphate markedly reduced both the IOP response and the effect of prostaglandin E2 on the protein content of the aqueous humour. 7. It is concluded that the production of local vasodilatation and increased permeability of the blood-aqueous barrier play an important part in the effect of prostaglandins on the IOP. The involvement of prostaglandins in the response of the rabbit eye to irritation is discussed. PMID:4981000

  2. Upcoming methods and specifications of continuous intraocular pressure monitoring systems for glaucoma

    Directory of Open Access Journals (Sweden)

    Amir Molaei

    2018-01-01

    Full Text Available Glaucoma is the leading cause of irreversible blindness and vision loss in the world. Although intraocular pressure (IOP is no longer considered the only risk factor for glaucoma, it is still the most important one. In most cases, high IOP is secondary to trabecular meshwork dysfunction. High IOP leads to compaction of the lamina cribrosa and subsequent damage to retinal ganglion cell axons. Damage to the optic nerve head is evident on funduscopy as posterior bowing of the lamina cribrosa and increased cupping. Currently, the only documented method to slow or halt the progression of this disease is to decrease the IOP; hence, accurate IOP measurement is crucial not only for diagnosis, but also for the management. Due to the dynamic nature and fluctuation of the IOP, a single clinical measurement is not a reliable indicator of diurnal IOP; it requires 24-hour monitoring methods. Technological advances in microelectromechanical systems and microfluidics provide a promising solution for the effective measurement of IOP. This paper provides a broad overview of the upcoming technologies to be used for continuous IOP monitoring.

  3. Common genetic determinants of intraocular pressure and primary open-angle glaucoma.

    Directory of Open Access Journals (Sweden)

    Leonieke M E van Koolwijk

    Full Text Available Intraocular pressure (IOP is a highly heritable risk factor for primary open-angle glaucoma and is the only target for current glaucoma therapy. The genetic factors which determine IOP are largely unknown. We performed a genome-wide association study for IOP in 11,972 participants from 4 independent population-based studies in The Netherlands. We replicated our findings in 7,482 participants from 4 additional cohorts from the UK, Australia, Canada, and the Wellcome Trust Case-Control Consortium 2/Blue Mountains Eye Study. IOP was significantly associated with rs11656696, located in GAS7 at 17p13.1 (p=1.4×10(-8, and with rs7555523, located in TMCO1 at 1q24.1 (p=1.6×10(-8. In a meta-analysis of 4 case-control studies (total N = 1,432 glaucoma cases, both variants also showed evidence for association with glaucoma (p=2.4×10(-2 for rs11656696 and p=9.1×10(-4 for rs7555523. GAS7 and TMCO1 are highly expressed in the ciliary body and trabecular meshwork as well as in the lamina cribrosa, optic nerve, and retina. Both genes functionally interact with known glaucoma disease genes. These data suggest that we have identified two clinically relevant genes involved in IOP regulation.

  4. Telemedicine-friendly, portable tonometers: an evaluation for intraocular pressure screening.

    Science.gov (United States)

    Kumar, Sajeesh; Middlemiss, Catherine; Bulsara, Max; Guibilato, Antonio; Morgan, William; Tay-Kearney, Mei-Ling; Constable, Ian J; Yogesan, Kanagasingam

    2006-01-01

    To evaluate the intraocular pressure (IOP) readings from two portable, telemedicine-friendly tonometers for suitability in glaucoma screening. 213 eyes of 107 consenting patients attending an eye clinic were tested with an I-care tonometer and a Pulsair-Easy Eye puff-air tonometer. Gold standard IOP was measured with a Goldmann applanation tonometer (GAT). Effect of central corneal thickness, anterior chamber depth and refractive errors on IOP measurements were also analysed. The mean difference of IOP by GAT and both the portable tonometers was +/- 2.2 mmHg. The analysis indicates minimal difference between IOP readings of both the portable tonometers. The mean difference between two consecutive readings by I-care was 0.01 mmHg. Using 21 mmHg as a threshold for suspected glaucoma, both the portable digital tonometers reported a sensitivity of 38% and specificity of >95%. In the subjects studied, central corneal thickness had statistically significant influence on IOP measurements while refractive errors and anterior chamber depth had no significant influence on IOP measurements with any tonometry. The IOP readings by both portable tonometers are comparable and were within clinically acceptable range from GAT. These portable tonometers are useful tools for IOP screening.

  5. INTRAOCULAR PRESSURE IN SOUTHERN ROCKHOPPER (EUDYPTES CHRYSOCOME) AND MACARONI PENGUINS (EUDYPTES CHRYSOLOPHUS): EVALUATION OF INFLUENCING FACTORS.

    Science.gov (United States)

    Woodhouse, Sarah J; Peterson, Edward L; Schmitt, Todd; Aquino, Susette

    2016-03-01

    Ophthalmic examinations were performed on 160 macaroni penguins (Eudyptes chrysolophus) and 90 southern rockhopper penguins (Eudyptes chrysocome) at eight North American zoos and aquaria. Intraocular pressure (IOP) was measured using rebound tonometry while penguins were held in two different body positions. Correlations between IOP and factors including age, body position, eye pathology, and housing parameters were evaluated. Normal macaroni penguins had a mean IOP of 42.0 ± 9.7 mm Hg. Normal rockhopper penguins had a mean IOP of 32.9 ± 6.2 mm Hg. Neither species had significantly different IOP between sexes or between left and right eyes of the same penguin. In both species, there was a negative linear correlation between age and IOP. In the macaroni population, IOP was significantly higher when IOP measurement was performed before ophthalmic exam; this was not true in rockhoppers. In both species, IOP measured in a horizontal body position was significantly higher than IOP measured in a vertical body position. In both species, eyes with corneal lesions had significantly lower IOP than normal eyes. In the macaroni penguin, eyes with rubeosis iridis had significantly lower IOP than normal eyes. In macaroni penguins, eyes with cataracts had significantly lower mean IOP than normal eyes; this was not true for rockhoppers.

  6. Determination of Tear Production and Intraocular Pressure With Rebound Tonometry in Wild Humboldt Penguins ( Spheniscus humboldti ).

    Science.gov (United States)

    Sheldon, Julie D; Adkesson, Michael J; Allender, Matthew C; Jankowski, Gwen; Langan, Jennifer; Cardeña, Marco; Cárdenas-Alayza, Susana

    2017-03-01

    Tear production and intraocular pressures (IOPs) were determined in 38 and 102 wild Humboldt penguins (Spheniscus humboldti), respectively, from the Punta San Juan Marine Protected Area in Ica, Peru. Tear production was measured by Schirmer tear test, and IOP was measured with a TonoVet rebound tonometer. Adult (n = 90) and chick (n = 12) penguins were sampled from 2 different beaches (north and south facing) during 2 sampling years (2010 and 2011). Results showed a mean ± SD (range) of 9 ± 4 (2-20) mm/min for tear production and 28 ± 9 (3-49) mm Hg for IOP. Tear production in penguins differed between beach and sex, whereas IOP differed between age, year, and beach. The IOPs were negatively correlated with packed cell volume. Tear production and IOP values had greater variation in this population than it has in other avian species. Previous investigations of IOP and tear production in Spheniscus species were conducted with birds housed under professional care in artificial marine and freshwater environments. This is the first study, to our knowledge, investigating tear production and IOP in wild penguins and establishes valuable reference intervals for this species.

  7. Comparison of the Effect of Atracurium and Cisatracurium on Intraocular Pressure and Pupillary Diameter

    Directory of Open Access Journals (Sweden)

    Mansoor Masjedi

    2013-10-01

    Full Text Available Purpose: Although there are ample evidences for the effects (mostly decrease of intraocular pressure (IOP after the administration of atracurium and cisatracurium during general anesthesia in ophthalmic operations, no study has yet been done to compare their effects on both IOP and pupillary diameter (PD simultaneously. The aim of this study was to determine whether there is any difference between the effects of atracurium and cisatracurium on IOP and PD.Methods: Sixty patients with American Society of Anesthesiologists class I-II without history of previous eye surgery were studied in two randomly divided, double-blind groups. Following induction of anesthesia, atracurium (0.6 mg/kg and cisatracurium (0.15 mg/kg were administered to each group. IOP was measured by applanation tonometry (TONO – PEN ® XL and PD (COLVARD pupillometer at six sequential occasions, before induction of anesthesia, 2 and 5 minutes after induction and 2, 5 and 10 minutes after intubation prior to initiation of operation. Then they were compared to each other.Results: Trend of recorded IOP and PD values showed that there were no statistically significant differences between atracurium and cisatracurium according to their effect on IOP (p=0.125 and PD (p>0.137 during the course of study. Conclusion: It seems that both atracurium and cisatracurium have similar effects on IOP and PD before and up to ten minutes after tracheal intubation prior to surgical intervention.

  8. The Application of a Contact Lens Sensor in Detecting 24-Hour Intraocular Pressure-Related Patterns

    Directory of Open Access Journals (Sweden)

    Sarah C. Xu

    2016-01-01

    Full Text Available Glaucoma is one of the leading causes of blindness worldwide. Recent studies suggest that intraocular pressure (IOP fluctuations, peaks, and rhythm are important factors in disease advancement. Yet, current glaucoma management remains hinged on single IOP measurements during clinic hours. To overcome this limitation, 24-hour IOP monitoring devices have been employed and include self-tonometry, permanent IOP, and temporary IOP monitoring. This review discusses each IOP measuring strategy and focuses on the recently FDA-approved contact lens sensor (CLS. The CLS records IOP-related ocular patterns for 24 hours continuously. Using the CLS, IOP-related parameters have been found to be associated with the rate of visual field progression in primary open-angle glaucoma, disease progression in primary angle-closure glaucoma, and various clinical variables in ocular hypertension. The CLS has been used to quantify blink rate and limbal strain and measure the circadian rhythm in a variety of disease states including normal-tension glaucoma and thyroid eye disease. The effects of various IOP-lowering interventions were also characterized using the CLS. CLS provides a unique, safe, and well-tolerated way to study IOP-related patterns in a wide range of disease states. IOP-related patterns may help identify patients most at risk for disease progression and assist with the development of tailored treatments.

  9. The Application of a Contact Lens Sensor in Detecting 24-Hour Intraocular Pressure-Related Patterns.

    Science.gov (United States)

    Xu, Sarah C; Gauthier, Angela C; Liu, Ji

    2016-01-01

    Glaucoma is one of the leading causes of blindness worldwide. Recent studies suggest that intraocular pressure (IOP) fluctuations, peaks, and rhythm are important factors in disease advancement. Yet, current glaucoma management remains hinged on single IOP measurements during clinic hours. To overcome this limitation, 24-hour IOP monitoring devices have been employed and include self-tonometry, permanent IOP, and temporary IOP monitoring. This review discusses each IOP measuring strategy and focuses on the recently FDA-approved contact lens sensor (CLS). The CLS records IOP-related ocular patterns for 24 hours continuously. Using the CLS, IOP-related parameters have been found to be associated with the rate of visual field progression in primary open-angle glaucoma, disease progression in primary angle-closure glaucoma, and various clinical variables in ocular hypertension. The CLS has been used to quantify blink rate and limbal strain and measure the circadian rhythm in a variety of disease states including normal-tension glaucoma and thyroid eye disease. The effects of various IOP-lowering interventions were also characterized using the CLS. CLS provides a unique, safe, and well-tolerated way to study IOP-related patterns in a wide range of disease states. IOP-related patterns may help identify patients most at risk for disease progression and assist with the development of tailored treatments.

  10. The Role of Low-frequency TRANS-orbital Magnetic Stimulation in Normalization of Intraocular Pressure in Patients with Primary Open-angle Glaucoma

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    I. A. Makarov

    2016-01-01

    Full Text Available Purpose. Assessment of the effectiveness of low-frequency magnetic therapy on the dynamics of intraocular pressure in the treatment of primary and uncompensated medical means of open-angle glaucoma. Patients and Methods. 46 patients with uncompensated open-angle glaucoma. The first group: 24 patients (42 eyes with open-angle glaucoma (I, II, III stages during 2–13 years. The second group: 22 patients (22 eyes with newly diagnosed elevated intraocular pressure in one eye. The age of patients ranged from 43 to 59 years. Treatment included antiglaucoma hypotensive eye drops and TRANS-orbital magnetic stimulation on the domestic device“Polus-2”. Results. Intraocular pressure before treatment ranged from 25 to 32 mm Hg. (average of 28.9±1.4 mm Hg. in the first group . After magnetic stimulation IOP decreased within 2–5 days in all patients to 18 to 21 mm Hg (average of 17.9±1.1 mm Hg, reaching values “pressure goal.” Second group: in the primary treatment in patients IOP was 28–39 mm Hg (average of 32.6±1.8 mm Hg on one of the eyes. IOP decreased to 16–21 mm Hg in the period from 3 to 9 days in all patients of study group after daily magnetic stimulation and instillation of xalatan and timolol. In the control subgroup of patients with uncompensated openangle glaucoma loweringof the IOP to “pressure goal,” noted only in 7 patients (70,0% 11–14 days after instillation of anti-hypertensive glaucoma eye drops only. Conclusion. Low-frequency TRANS-orbital magnetic stimulation in enhanced hypotensive effect antiglaucomatous eye drops and makes it easier to achieve compensation of IOP to values “pressure goals” in patients with uncompensated open-angle glaucoma. The marked dependence of the efficiency of reduction of IOP from biotropic parameters of the magnetic field. The pulsed mode with a higher amplitude value of the magnetic induction has a more pronounced effect and makes it easier to achieve the reduction of IOP.

  11. A randomised comparative study of the effect of Airtraq optical laryngoscope vs. Macintosh laryngoscope on intraocular pressure in non-ophthalmic surgery

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    Bikramjit Das

    2016-02-01

    Full Text Available BACKGROUND: We compared intraocular pressure changes following laryngoscopy and intubation with conventional Macintosh blade and Airtraq optical laryngoscope. METHODS: Ninety adult patients were randomly assigned to study group or control group. Study group (n = 45 - Airtraq laryngoscope was used for laryngoscopy. Control group (n = 45 - conventional Macintosh laryngoscope was used for laryngoscopy. Preoperative baseline intraocular pressure was measured with Schiotz tonometer. Laryngoscopy was done as per group protocol. Intraocular pressure and haemodynamic parameters were recorded just before insertion of the device and subsequently three times at an interval of one minute after insertion of the device. RESULTS: Patient characteristics, baseline haemodynamic parameters and baseline intraocular pressure were comparable in the two groups. Following insertion of the endotracheal tube with Macintosh laryngoscope, there was statistically significant rise in heart rate and intraocular pressure compared to Airtraq group. There was no significant change in MAP. Eight patients in Macintosh group had tongue-lip-dental trauma during intubation, while only 2 patients received upper airway trauma in Airtraq group. CONCLUSION: We conclude that Airtraq laryngoscope in comparison to Macintosh laryngoscope results in significantly fewer rises in intraocular pressure and clinically less marked increase in haemodynamic response to laryngoscopy and intubation.

  12. Association between urinary albumin excretion and intraocular pressure in type 2 diabetic patients without renal impairment.

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    Jin A Choi

    Full Text Available BACKGROUND: To assess the relationship between urinary albumin excretion and intraocular pressure (IOP in type 2 diabetes patients without renal impairment. METHODS: We explored the effects of albuminuria on high IOP in 402 non-glaucomatous type 2 diabetes without renal impairment who participated in the 2011 Korean National Health and Nutrition Examination Survey (KNHANES. Multiple logistic regression analysis was used to assess the relationship between log-transformed albumin/creatinine ratio (ACR tertiles and an IOP of ≥ 18 mmHg after adjusting for age, gender, hypertension, body mass index, triglycerides, area of residence, and education level. RESULTS: Subjects with a high IOP ≥ 18 mmHg were more likely to be current smokers (P = 0.038, heavy drinkers (P = 0.006, and to have high systolic blood pressure (P = 0.016, triglycerides (P = 0.008, and a higher log-transformed ACR (P = 0.022.In multivariate regression analysis, ACR tertile was associated with the prevalence of high IOP significantly (P = 0.022. The associations between ACR tertiles and high IOP were significant in overweight patients and those with abdominal obesity (P = 0.003 and 0.003, respectively. In contrast, there were no associations in the subgroup of patients who were not overweight and those without abdominal obesity (P = 0.291 and 0.561, respectively. CONCLUSIONS: Urinary albumin excretion is associated with high IOP in the type 2 diabetes population without renal insufficiency. The effect of the albuminuria on IOP was evident in a subgroup of patients with components of metabolic syndrome.

  13. Intraocular pressure following 18 hours of systemic dehydration in ocular normotensive healthy subjects

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    Faustina K. Idu

    2015-07-01

    Full Text Available Aim: To investigate the effect of dehydration on intraocular pressure (IOP. Subjects: The study population comprised 50 subjects (27 men and 23 women with a mean age of 42.84 ± 2.64 years. Method: The subjects dehydrated for 18 hours. IOP was assessed in both eyes using the Perkins handheld applanation tonometer. Baseline measurement of IOP was taken before the subjects dehydrated for 18 hours and repeated after dehydration. Blood samples were taken before and after dehydration for the determination of plasma osmolality and plasma antidiuretic hormone (ADH concentrations. Results: A statistically significant (p < 0.001 reduction in the mean weight of subjects occurred after dehydration. There was a significant reduction in IOP from 16.68 mmHg ± 0.32 mmHg to 13.08 mmHg ± 0.31 mmHg after dehydration (p < 0.001. Mean plasma osmolality showed a statistically significant increase (p < 0.05 from baseline of 290.02 mOsmol/kg ± 1.25 mOsmol/kg to 294.96 mOsmol/kg ± 1.33 mOsmol/kg after dehydration. There was also a significant increase (p < 0.05 in mean plasma ADH concentration from 5.36 pg/mL ± 0.21 pg/mL to 6.40 pg/mL ± 0.20 pg/mL after dehydration. There were no significant differences in both systolic and diastolic blood pressures before and after dehydration. Conclusion: Dehydration decreases IOP in healthy humans; this decrease probably results from an increase in plasma osmolality and plasma ADH concentrations.

  14. Correlation of endothelin-1 concentration in aqueous humor with intraocular pressure in primary open angle and pseudoexfoliation glaucoma.

    Science.gov (United States)

    Choritz, Lars; Machert, Maren; Thieme, Hagen

    2012-10-23

    Endothelin-1 (ET-1) has been found in elevated concentrations in the aqueous humor of glaucoma patients. Indirect evidence from animal studies suggests that ET-1 might directly influence intraocular pressure (IOP). The aim of this study was to determine whether ET-1 concentrations in aqueous humor of cataract and glaucoma patients correlate with IOP. Aqueous humor and blood samples from patients with either cataract (control, n = 38), primary open angle glaucoma (POAG, n = 35), or pseudoexfoliation glaucoma (PEXG, n = 21), without other ocular or systemic disease, were collected during routine cataract surgery or trabeculectomy. ET-1 concentration was determined by an ET-1 ELISA kit. IOP was measured preoperatively by standard Goldmann applanation tonometry. All statistical analysis was performed using commercial predictive analytics software. Both IOP and ET-1 concentration in aqueous humor were significantly increased in POAG (23.4 ± 6.8 mm Hg, 5.9 ± 2.9 pg/mL) and PEXG (24.3 ± 8.8 mm Hg, 7.7 ± 2.1 pg/mL) compared with control (15.0 ± 2.9 mm Hg, 4.3 ± 2.4 pg/mL). No difference was detected for plasma ET-1 concentrations. IOP and ET-1 in the aqueous humor were significantly correlated (R = 0.394, R² = 0.155, P < 0.001), although no correlation was found between IOP and ET-1 in blood plasma or between ET-1 in aqueous humor and ET-1 in plasma. In this study, a small but highly significant correlation between IOP and the ET-1 concentration in the aqueous humor was found. Although no causative relationship can be deduced from this, ocular ET-1 effects on IOP control may merit further investigation.

  15. The post-natal development of intraocular pressure in normal domestic cats (Felis catus) and in feline congenital glaucoma.

    Science.gov (United States)

    Adelman, Sara; Shinsako, Daniel; Kiland, Julie A; Yaccarino, Vincent; Ellinwood, N Matthew; Ben-Shlomo, Gil; McLellan, Gillian J

    2018-01-01

    Intraocular pressure (IOP) is the most consistent risk factor for progressive vision loss in glaucoma. Cats with recessively inherited feline congenital glaucoma (FCG) exhibit elevated IOP with gradual, painless progression of glaucoma similar to humans and are studied as a model of glaucoma in humans and animals. Here, post-natal development of IOP was characterized in normal domestic cats and in cats with FCG caused by a homozygous LTBP2 mutation. Rebound tonometry (TonoVet ® , ICare Oy, Finland) was used to measure IOP non-invasively, 2-3 times weekly in 63 FCG and 33 normal kittens, of both sexes, from eyelid opening until 3-6 months of age. IOPs in the left and right eyes of both FCG and normal kittens were compared by paired t-test and linear regression. One-way ANOVA and Tukey-Kramer post-tests were used to compare IOP of cats grouped by age and disease status. A p-value normal kittens and 8.72 mmHg (SD = 1.4) in kittens with FCG. Mean IOP at age 10 weeks was significantly higher in FCG (19.8 mmHg; 95% CI = 17.7, 21.9  mmHg) than in normal kittens (13.2 mmHg; 95% CI = 11.9, 14.5  mmHg). At 3 months of age, IOP in normal cats reached adult values while IOP in FCG cats continued to increase through at least six months of age. These results provide ranges for normal IOP values in young kittens and confirm that IOP is significantly higher than normal by 10wks of age in this spontaneous feline glaucoma model. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Intraocular pressure and its correlation with midnight plasma cortisol level in Cushing's disease and other endogenous Cushing's syndrome

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    Priyadarshini Mishra

    2017-01-01

    Full Text Available Purpose: The purpose of this study is to measure intraocular pressure (IOP and evaluate the correlation between IOP and midnight plasma cortisol (MPC level in patients with Cushing's disease (CD and other endogenous Cushing's syndrome (ECS. Methods: This is a cross-sectional study from a single center including newly diagnosed patients with CD or ECS. All patients underwent detailed ophthalmological evaluation. IOP was measured by Goldmann applanation tonometry in the morning and evening on two consecutive days. MPC value was obtained for each patient. The data were compared using paired and unpaired t-test, Mann–Whitney U-test, and Spearman's rank correlation coefficient. Results: Among 32 patients, 22 were CD (68.75% and 10 patients were other ECS (31.25%. A total of 25 patients (78.12% in our study group had normal IOP (<22 mmHg, and seven patients (21.88% had increased IOP (≥22 mmHg. The percentage of patients with normal IOP was found to be significantly higher compared to percentage of patients with high IOP (P = 0.001 using one-sample Chi-square test. Mean MPC value was 468.6 ± 388.3 nmol/L in patients having IOP ≥22 mmHg and 658.5 ± 584 nmol/L in those with IOP <22 mmHg from both CD and ECS groups, but the difference was not statistically significant. No correlation was found between IOP and MPC (Spearman's rank correlation rho = −0.16 [P = 0.38]. Conclusion: In CD and ECS patients, IOP elevation is an uncommon feature, and high IOP in either group does not correlate with MPC level.

  17. Clinical utility and differential effects of prostaglandin analogs in the management of raised intraocular pressure and ocular hypertension

    Directory of Open Access Journals (Sweden)

    Anne J Lee

    2010-07-01

    Full Text Available Anne J Lee1,2, Peter McCluskey2,31Manchester Royal Eye Hospital, Manchester, UK; 2University of Sydney, Sydney, Australia; 3Sydney Eye Hospital, Sydney, AustraliaAbstract: Prostaglandin analogs (PGA are powerful topical ocular hypotensive agents available for the treatment of elevated intraocular pressure (IOP. Latanoprost 0.005% and travoprost 0.004% are prodrugs and analogs of prostaglandin F2a. Bimatoprost 0.03% is regarded as a prostamide, and debate continues as to whether it is a prodrug. The free acids of all 3 PGAs reduce IOP by enhancing uveoscleral and trabecular outflow via direct effects on ciliary muscle relaxation and remodeling of extracellular matrix. The vast majority of clinical trials demonstrate IOP-lowering superiority of latanoprost, bimatoprost and travoprost compared with timolol 0.5%, brimonidine 0.2%, or dorzolamide 2% monotherapy. Bimatoprost appears to be more efficacious in IOP-lowering compared with latanoprost, with weighted mean difference in IOP reduction documented in one meta-analysis of 2.59% to 5.60% from 1- to 6-months study duration. PGAs reduce IOP further when used as adjunctive therapy. Fixed combinations of latanoprost, bimatoprost or travoprost formulated with timolol 0.5% and administered once daily are superior to monotherapy of its constituent parts. PGA have near absence of systemic side effects, although do have other commonly encountered ocular adverse effects. The adverse effects of PGA, and also those found more frequently with bimatoprost use include ocular hyperemia, eyelash growth, and peri-ocular pigmentary changes. Iris pigmentary change is unique to PGA treatment. Once daily administration and near absence of systemic side effects enhances tolerance and compliance. PGAs are often prescribed as first-line treatment for ocular hypertension and open-angle glaucoma.Keywords: prostaglandin analog, glaucoma, ocular hypertension, latanoprost, bimatoprost, travoprost

  18. Effects of premedication with oral gabapentin on intraocular pressure changes following tracheal intubation in clinically normal dogs.

    Science.gov (United States)

    Trbolova, Alexandra; Ghaffari, Masoud Selk; Capik, Igor

    2017-09-19

    Gabapentin is an antiepileptic drug widely approved as an add-on therapy for epilepsy treatment in human and dogs. There is a clinical impression that gabapentin is a suitable drug which attenuates the IOP elevation associated with tracheal intubation in humans. The present study performed to determine the effects of oral gabapentin on intraocular pressure (IOP) changes following tracheal intubation in dogs. Twenty adult healthy dogs were randomly assigned to treatment (n = 10) and control (n = 10) groups. Dogs in the treatment group received oral gabapentin (50 mg/kg) 2 h before induction of anesthesia and dogs in the control group received oral gelatin capsule placebo at the same time. The dogs were anesthetized with propofol 6 mg/kg, and anesthesia was maintained with a constant infusion of 0.2 mg/kg/min of propofol for 20 min. IOP were measured immediately before induction and then repeated immediately after induction, as well as 5 min, 10 min and 15 min following tracheal intubation in both groups. IOP was significantly higher immediately after induction, and 5 min after tracheal intubation when compared with IOP reading before induction in the control group. There was no statistically significant change in IOPs immediately after induction, and 5 min after tracheal intubation in comparison to the values before induction in the treatment group. Based on the findings of this study, preanesthetic oral administration of gabapentin significantly prevents an increase in the IOP associated with tracheal intubation in dogs anesthetized with propofol.

  19. Magic angle-enhanced MRI of fibrous microstructures in sclera and cornea with and without intraocular pressure loading.

    Science.gov (United States)

    Ho, Leon C; Sigal, Ian A; Jan, Ning-Jiun; Squires, Alexander; Tse, Zion; Wu, Ed X; Kim, Seong-Gi; Schuman, Joel S; Chan, Kevin C

    2014-08-07

    The structure and biomechanics of the sclera and cornea are central to several eye diseases such as glaucoma and myopia. However, their roles remain unclear, partly because of limited noninvasive techniques to assess their fibrous microstructures globally, longitudinally, and quantitatively. We hypothesized that magic angle-enhanced magnetic resonance imaging (MRI) can reveal the structural details of the corneoscleral shell and their changes upon intraocular pressure (IOP) elevation. Seven ovine eyes were extracted and fixed at IOP = 50 mm Hg to mimic ocular hypertension, and another 11 eyes were unpressurized. The sclera and cornea were scanned at different angular orientations relative to the main magnetic field inside a 9.4-Tesla MRI scanner. Relative MRI signal intensities and intrinsic transverse relaxation times (T2 and T2*) were determined to quantify the magic angle effect on the corneoscleral shells. Three loaded and eight unloaded tendon samples were scanned as controls. At magic angle, high-resolution MRI revealed distinct scleral and corneal lamellar fibers, and light/dark bands indicative of collagen fiber crimps in the sclera and tendon. Magic angle enhancement effect was the strongest in tendon and the least strong in cornea. Loaded sclera, cornea, and tendon possessed significantly higher T2 and T2* than unloaded tissues at magic angle. Magic angle-enhanced MRI can detect ocular fibrous microstructures without contrast agents or coatings and can reveal their MR tissue property changes with IOP loading. This technique may open up new avenues for assessment of the biomechanical and biochemical properties of ocular tissues in aging and in diseases involving the corneoscleral shell. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

  20. Magic Angle–Enhanced MRI of Fibrous Microstructures in Sclera and Cornea With and Without Intraocular Pressure Loading

    Science.gov (United States)

    Ho, Leon C.; Sigal, Ian A.; Jan, Ning-Jiun; Squires, Alexander; Tse, Zion; Wu, Ed X.; Kim, Seong-Gi; Schuman, Joel S.; Chan, Kevin C.

    2014-01-01

    Purpose. The structure and biomechanics of the sclera and cornea are central to several eye diseases such as glaucoma and myopia. However, their roles remain unclear, partly because of limited noninvasive techniques to assess their fibrous microstructures globally, longitudinally, and quantitatively. We hypothesized that magic angle–enhanced magnetic resonance imaging (MRI) can reveal the structural details of the corneoscleral shell and their changes upon intraocular pressure (IOP) elevation. Methods. Seven ovine eyes were extracted and fixed at IOP = 50 mm Hg to mimic ocular hypertension, and another 11 eyes were unpressurized. The sclera and cornea were scanned at different angular orientations relative to the main magnetic field inside a 9.4-Tesla MRI scanner. Relative MRI signal intensities and intrinsic transverse relaxation times (T2 and T2*) were determined to quantify the magic angle effect on the corneoscleral shells. Three loaded and eight unloaded tendon samples were scanned as controls. Results. At magic angle, high-resolution MRI revealed distinct scleral and corneal lamellar fibers, and light/dark bands indicative of collagen fiber crimps in the sclera and tendon. Magic angle enhancement effect was the strongest in tendon and the least strong in cornea. Loaded sclera, cornea, and tendon possessed significantly higher T2 and T2* than unloaded tissues at magic angle. Conclusions. Magic angle–enhanced MRI can detect ocular fibrous microstructures without contrast agents or coatings and can reveal their MR tissue property changes with IOP loading. This technique may open up new avenues for assessment of the biomechanical and biochemical properties of ocular tissues in aging and in diseases involving the corneoscleral shell. PMID:25103267

  1. Genetic correlations between intraocular pressure, blood pressure and primary open-angle glaucoma: a multi-cohort analysis.

    Science.gov (United States)

    Aschard, Hugues; Kang, Jae H; Iglesias, Adriana I; Hysi, Pirro; Cooke Bailey, Jessica N; Khawaja, Anthony P; Allingham, R Rand; Ashley-Koch, Allison; Lee, Richard K; Moroi, Sayoko E; Brilliant, Murray H; Wollstein, Gadi; Schuman, Joel S; Fingert, John H; Budenz, Donald L; Realini, Tony; Gaasterland, Terry; Scott, William K; Singh, Kuldev; Sit, Arthur J; Igo, Robert P; Song, Yeunjoo E; Hark, Lisa; Ritch, Robert; Rhee, Douglas J; Gulati, Vikas; Haven, Shane; Vollrath, Douglas; Zack, Donald J; Medeiros, Felipe; Weinreb, Robert N; Cheng, Ching-Yu; Chasman, Daniel I; Christen, William G; Pericak-Vance, Margaret A; Liu, Yutao; Kraft, Peter; Richards, Julia E; Rosner, Bernard A; Hauser, Michael A; Klaver, Caroline C W; vanDuijn, Cornelia M; Haines, Jonathan; Wiggs, Janey L; Pasquale, Louis R

    2017-11-01

    Primary open-angle glaucoma (POAG) is the most common chronic optic neuropathy worldwide. Epidemiological studies show a robust positive relation between intraocular pressure (IOP) and POAG and modest positive association between IOP and blood pressure (BP), while the relation between BP and POAG is controversial. The International Glaucoma Genetics Consortium (n=27 558), the International Consortium on Blood Pressure (n=69 395), and the National Eye Institute Glaucoma Human Genetics Collaboration Heritable Overall Operational Database (n=37 333), represent genome-wide data sets for IOP, BP traits and POAG, respectively. We formed genome-wide significant variant panels for IOP and diastolic BP and found a strong relation with POAG (odds ratio and 95% confidence interval: 1.18 (1.14-1.21), P=1.8 × 10 -27 ) for the former trait but no association for the latter (P=0.93). Next, we used linkage disequilibrium (LD) score regression, to provide genome-wide estimates of correlation between traits without the need for additional phenotyping. We also compared our genome-wide estimate of heritability between IOP and BP to an estimate based solely on direct measures of these traits in the Erasmus Rucphen Family (ERF; n=2519) study using Sequential Oligogenic Linkage Analysis Routines (SOLAR). LD score regression revealed high genetic correlation between IOP and POAG (48.5%, P=2.1 × 10 -5 ); however, genetic correlation between IOP and diastolic BP (P=0.86) and between diastolic BP and POAG (P=0.42) were negligible. Using SOLAR in the ERF study, we confirmed the minimal heritability between IOP and diastolic BP (P=0.63). Overall, IOP shares genetic basis with POAG, whereas BP has limited shared genetic correlation with IOP or POAG.

  2. Effects of timolol maleate, levobunolol and apraclonidine on intraocular pressure, pupil size, blood pressure and heart rate in beagles

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    I.R.M. Padua

    2016-06-01

    Full Text Available ABSTRACT The aim of this study was to evaluate changes in intraocular pressure (IOP, pupil size (PS, blood pressure (BP, heart rate (HR, and ECG variables (Pms wave PmV, PR interval, QRS complex, RMV wave and QT intervals over time during the instillation of 0.5% timolol, 0.5% levobunolol and 0.5% apraclonidine in clinically normal dogs. Ten adult beagles were used. Baseline values were measured at 8a.m., 2p.m. and 8p.m., for three consecutive days. A waiting period of 10 days between the administrations of each drug was established. For 15 consecutive days, the drug being tested was instilled in one eye of each dog twice a day (7a.m. and 7p.m.. The parameters were evaluated at the aforementioned times on days 3, 6, 9, 12 and 15. Data were statistically compared using the Bonferroni test and one-way repeated measures analysis of variance (P<0.05. The Pearson test was used to evaluate any correlation between QT interval, HR and BP. The tested drugs did not find a decrease in IOP. A significant decreased in PS was observed in almost all dogs following levobunolol administration, relative to the control eye. A significant decrease in HR was observed on day 3 following levobunolol treatment, while apraclonidine induced an increase on day 15. Blood pressure was reduced in all measurement time points following apraclonidine treatment. A negative correlation between QT interval and HR was only observed in dogs treated with timolol. In conclusion, levobunolol was the only drug that induced significant alterations in PS. Apraclonidine was the only drug that induced systemic hypotension. Timolol was the only drug to that induced a negative correlation between QT and HR.

  3. The hidden magnitude of raised blood pressure and elevated blood ...

    African Journals Online (AJOL)

    Conclusions: The prevalence of undiagnosed raised blood pressure and elevated blood sugar was high in Ethiopia and only very small percentage of people had been aware of their high blood pressure and elevated blood sugar. Policy makers in the health sector including other health development partners need to ...

  4. Cerebral Pulsatility Index Is Elevated in Patients with Elevated Right Atrial Pressure.

    Science.gov (United States)

    Lahiri, Shouri; Schlick, Konrad H; Padrick, Matthew M; Rinsky, Brenda; Gonzalez, Nestor; Jones, Heather; Mayer, Stephan A; Lyden, Patrick D

    2018-01-01

    Extracerebral venous congestion can precipitate intracranial hypertension due to obstruction of cerebral blood outflow. Conditions that increase right atrial pressure, such as hypervolemia, are thought to increase resistance to jugular venous outflow and contribute to cerebro-venous congestion. Cerebral pulsatility index (CPI) is considered a surrogate marker of distal cerebrovascular resistance and is elevated with intracranial hypertension. Thus, we sought to test the hypothesis that elevated right atrial pressure is associated with increased CPI compared to normal right atrial pressure. We retrospectively reviewed 61 consecutive patients with subarachnoid hemorrhage. We calculated CPI from transcranial Doppler studies and correlated these with echocardiographic measures of right atrial pressure. CPIs were compared from patients with elevated and normal right atrial pressure. There was a significant difference between CPI obtained from all patients with elevated right atrial pressure compared to those with normal right atrial pressure (P right and left hemispheric CPI from patients with both elevated and normal right atrial pressure. Patients with elevated right atrial pressure had significantly higher CPI compared to patients with normal right atrial pressure. These findings suggest that cerebro-venous congestion due to impaired jugular venous outflow may increase distal cerebrovascular resistance as measured by CPI. Since elevated CPI is associated with poor outcome in numerous neurological conditions, future studies are needed to elucidate the significance of these results in other populations. Copyright © 2017 by the American Society of Neuroimaging.

  5. Potential effects of systematic errors in intraocular pressure measurements on screening for ocular hypertension.

    Science.gov (United States)

    Turner, M J; Graham, S L; Avolio, A P; Mitchell, P

    2013-04-01

    Raised intraocular pressure (IOP) increases the risk of glaucoma. Eye-care professionals measure IOP to screen for ocular hypertension (OHT) (IOP>21 mm Hg) and to monitor glaucoma treatment. Tonometers commonly develop significant systematic measurement errors within months of calibration, and may not be verified often enough. There is no published evidence indicating how accurate tonometers should be. We analysed IOP measurements from a population study to estimate the sensitivity of detection of OHT to systematic errors in IOP measurements. We analysed IOP data from 3654 participants in the Blue Mountains Eye Study, Australia. An inverse cumulative distribution indicating the proportion of individuals with highest IOP>21 mm Hg was calculated. A second-order polynomial was fitted to the distribution and used to calculate over- and under-detection of OHT that would be caused by systematic measurement errors between -4 and +4 mm Hg. We calculated changes in the apparent prevalence of OHT caused by systematic errors in IOP. A tonometer that consistently under- or over-reads by 1 mm Hg will miss 34% of individuals with OHT, or yield 58% more positive screening tests, respectively. Tonometers with systematic errors of -4 and +4 mm Hg would miss 76% of individuals with OHT and would over-detect OHT by a factor of seven. Over- and under-detection of OHT are not strongly affected by cutoff IOP. We conclude that tonometers should be maintained and verified at intervals short enough to control systematic errors in IOP measurements to substantially less than 1 mm Hg.

  6. Assessment of Corneal Biomechanical Properties and Intraocular Pressure in Myopic Spanish Healthy Population

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    María A. del Buey

    2014-01-01

    Full Text Available Purpose. To examine biomechanical parameters of the cornea in myopic eyes and their relationship with the degree of myopia in a western healthy population. Methods. Corneal hysteresis (CH, corneal resistance factor (CRF, Goldmann correlated intraocular pressure (IOP, and corneal compensated IOP (IOPcc were measured using the ocular response analyzer (ORA in 312 eyes of 177 Spanish subjects aged between 20 and 56 years. Refraction was expressed as spherical equivalent (SE, which ranged from 0 to −16.50 diopters (D (mean: −3.88±2.90 D. Subjects were divided into four groups according to their refractive status: group 1 or control group: emmetropia (-0.50≤SE0.05; nevertheless, IOPcc was significantly higher in the moderately myopic (15.47±2.47 mmHg and highly myopic (16.14±2.59 mmHg groups than in the emmetropia (15.15±2.06 mmHg and low myopia groups (14.53±2.37 mmHg. No correlation between age and the measured parameters was found. CH and IOPcc were weakly but significantly correlated with SE (r=0.171, P=0.002 and r=-0.131, P=0.021, resp.. Conclusions. Present study showed only a very weak, but significant, correlation between CH and refractive error, with CH being lower in both moderately and highly myopic eyes than that in the emmetropic and low myopic eyes. These changes in biomechanical properties of the cornea may have an impact on IOP measurement, increasing the risk of glaucoma.

  7. Is the tono-pen accurate for measuring intraocular pressure in young children with congenital glaucoma?

    Science.gov (United States)

    Levy, Jaime; Lifshitz, Tova; Rosen, Shirley; Tessler, Zvi; Biedner, Ben-Zion

    2005-08-01

    We sought to compare intraocular pressure (IOP) measurements by Perkins tonometer and Tono-Pen in young children with primary congenital glaucoma (PCG). This was a retrospective comparative case series. We reviewed the clinical records of all children with primary congenital glaucoma who underwent examinations under general anesthesia at Soroka University Medical Center between January 1999 and July 2002. Our main outcome measures were IOP with Perkins hand-held tonometer and Tono-Pen tonometer. A total of 28 eyes of 16 children were examined under general anesthesia. The mean IOP was 18 +/- 6 mm Hg with the Perkins tonometer and 22 +/- 8 mm Hg with the Tono-Pen. In 18 eyes, IOP was less than 21 mm Hg with the Perkins tonometer; these eyes had already undergone surgical procedures. The other 10 eyes with IOP greater than 21 mm Hg with the Perkins tonometer underwent surgery at the end of the examination under anesthesia. In eyes with IOP greater than 16 mm Hg (Group A, n = 18), a significant difference (P < 0.001) was found between the Perkins and Tono-Pen measurements, even although the values were strongly correlated (r = 0.60). In contrast, in eyes with IOP less than 16 mm Hg (Group B, n = 10) no statistically significant difference (P = 0.28) and good correlation (r = 0.78) were obtained. A difference of 5.8 +/- 3.8 mm Hg and 0.6 +/- 1.7 mm Hg between Perkins and Tono-Pen readings, respectively, was found in Groups A and B. Tono-Pen readings disagree with Perkins tonometer measurements for measuring IOP in children with PCG who present with IOP greater than 16 mm Hg and tends to overestimate IOP. A further study with a similar population is necessary to confirm these results.

  8. Examiner Handedness and the Effects on Intraocular Pressure Readings Using the Tono-Pen XL.

    Science.gov (United States)

    Hacopian, Alexander G; Rushing, Lauren C; Chuang, Alice Z; Bell, Nicholas P; Kumar, Kartik S; Feldman, Robert M

    2017-08-01

    To assess the effect of examiner handedness on intraocular pressure (IOP) readings using the Tono-Pen XL in eyes without corneal pathology or previous ocular surgeries. Patients 18 years of age or older were included in this prospective study. Participants who had a history of corneal conditions or other characteristics that would prevent reliable IOP measurements were excluded. Five experienced examiners, 2 right-hand dominant and 3 left-hand dominant, took bilateral IOP measurements with a Tono-Pen XL. Each participant was tested by 2 examiners, 1 left-handed and 1 right-handed, in a random order. The time between each examiner's measurements was 15 minutes. A paired t test was used to compare IOP differences between "near" (right eye for right-hand or left eye for left-hand dominant examiner) and "far" (right eye by left-hand or left eye by right-hand dominant examiner) measurements for each eye. Forty-six participants with a mean age of 33.8 years (±12.8) were enrolled. No significant difference in IOP between near and far eyes was found (IOP difference=IOPfar-IOPnear=-0.11 [±2.74] mm Hg; P=0.70). Right-hand dominant examiners consistently measured significantly higher IOP (0.83±2.03 mm Hg; P=0.008) compared with left-hand dominant examiners, regardless of the relative position of the eye with respect to the examiner. The results suggest that IOP readings are not influenced by the positioning of the patient relative to the dominant hand of the examiner.

  9. Positive correlation between Tono-Pen intraocular pressure and central corneal thickness.

    Science.gov (United States)

    Dohadwala, A A; Munger, R; Damji, K F

    1998-10-01

    To examine the relationship between intraocular pressure (IOP) readings taken by the Tono-Pen tonometer (Mentor O&O, Norwell, MA) and central corneal thickness (CCT). Prospective cross-sectional population study. There were 651 eyes of 332 healthy subjects. A questionnaire was given to each subject requesting information on gender, age, race, and other factors that can influence IOP. The IOP then was measured using the Tono-Pen followed by measurements of CCT using an ultrasonic pachymeter. The IOP was found to increase by 2.9 mmHg/100 microns CCT in males and 1.2 mmHg/100 microns in females. For males, CCT was found to be statistically significant in predicting IOP (P < 0.001 in the right and left eyes) and diabetes was of borderline significance (P = 0.012 in the right eye, P = 0.089 in the left eye). For females, CCT was of borderline significance (P = 0.064 in the right eye, P = 0.019 in the left eye). In females, a family history of glaucoma (P = 0.021 in the right eye, P = 0.022 in the left eye) and hypertension (P = 0.010 in the right eye, P = < 0.001 in the left eye) were also significant in the prediction of IOP. Race was found to be a significant predictor of CCT (P < 0.001 in both right and left eyes) for both males and females. Clinicians should be aware that, as with the Goldmann applanation tonometer, the Tono-Pen has a systematic error in IOP readings caused by its dependence on CCT. Tono-Pen IOP readings are positively correlated to CCT in males and, to a lesser extent, in females as well. The CCT measurements should be considered to ensure proper interpretation of IOP measurements in the diagnosis and management of disorders in which the CCT or IOP readings are outside normal limits.

  10. Effects of submaximal exercise with water ingestion on intraocular pressure in healthy human males

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    Moura M.A.

    2002-01-01

    Full Text Available The effects of exercise and water replacement on intraocular pressure (IOP have not been well established. Furthermore, it is not known whether the temperature of the fluid ingested influences the IOP response. In the present study we determined the effect of water ingestion at three temperatures (10, 24 and 38ºC; 600 ml 15 min before and 240 ml 15, 30 and 45 min after the beginning of each experimental session on the IOP of six healthy male volunteers (age = 24.0 ± 3.5 years, weight = 67.0 ± 4.8 kg, peak oxygen uptake (VO2peak = 47.8 ± 9.1 ml kg-1 min-1. The subjects exercised until exhaustion on a cycle ergometer at a 60% VO2peak in a thermoneutral environment. IOP was measured before and after exercise and during recovery (15, 30 and 45 min using the applanation tonometry method. Skin and rectal temperatures, heart rate and oxygen uptake were measured continuously. IOP was similar for the right eye and the left eye and increased post-water ingestion under both exercising and resting conditions (P<0.05 but did not differ between resting and exercising situations, or between the three water temperatures. Time to exhaustion was not affected by the different water temperatures. Rectal temperature, hydration status, heart rate, oxygen uptake, carbon dioxide extraction and lactate concentration were increased by exercise but were not affected by water temperature. We conclude that IOP was not affected by exercise and that water ingestion increased IOP as expected, regardless of water temperature.

  11. [Alterations in intraocular pressure and the CorVis parameters after LASIK].

    Science.gov (United States)

    Anton, A; Neuburger, M; Jordan, J F; Wecker, T; Lübke, J; Heinzelmann, S; Lapp, T; Böhringer, D; Reinhard, T; Maier, P

    2017-05-01

    The reduction of corneal thickness following laser-assisted in-situ keratomileusis (LASIK) requires a correction of intraocular pressure (IOP) measurements. The corneal visualization Scheimpflug technology (CorVis ST, Oculus, Wetzlar, Germany) not only measures the IOP and central corneal thickness (CCT) but also determines 10 additional corneal parameters, such as the time to first and second applanation and velocity. Besides CCT we compared various corneal parameters before and after LASIK in order to detect possible correlations and to correct IOP measurements. Measurements with CorVis ST were made before and after LASIK in 45 myopic patients (45 left eyes). We compared the IOP and CorVis ST parameters using a paired t‑test before and after LASIK and corrected for possible correlations in a multifactorial linear model. Finally, we correlated the changes in IOP to changes in biomechanical parameters. We observed a direct correlation between the IOP measurements and the corneal thickness. The IOP was underestimated by 0.039 mm Hg per micrometer in reduction of corneal thickness. The multifactorial linear model showed a correlation of IOP change to A2 velocity and the radius of applanation. Surgical thinning of the central cornea via LASIK demonstrated a direct correlation between corneal thickness and IOP measurements using the CorVis ST technique. Postoperative changes of the A2 velocity and the applanation radius also had a statistically significant influence on post-LASIK IOP measurements. Our findings could be useful to obtain more precise post-LASIK IOP measurements.

  12. Intraocular pressure in genetically distinct mice: an update and strain survey

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    Tomarev Stanislav I

    2001-08-01

    Full Text Available Abstract Background Little is known about genetic factors affecting intraocular pressure (IOP in mice and other mammals. The purpose of this study was to determine the IOPs of genetically distinct mouse strains, assess the effects of factors such as age, sex and time of day on IOP in specific strain backgrounds, and to assess the effects of specific candidate gene mutations on IOP. Results Based on over 30 studied mouse strains, average IOP ranges from approximately 10 to 20 mmHg. Gender does not typically affect IOP and aging results in an IOP decrease in some strains. Most tested strains exhibit a diurnal rhythm with IOP being the highest during the dark period of the day. Homozygosity for a null allele of the carbonic anhydrase II gene (Car2n does not alter IOP while homozygosity for a mutation in the leptin receptor gene (Leprdb that causes obesity and diabetes results in increased IOP. Albino C57BL/6J mice homozygous for a tyrosinase mutation (Tyrc-2J have higher IOPs than their pigmented counterparts. Conclusions Genetically distinct mouse strains housed in the same environment have a broad range of IOPs. These IOP differences are likely due to interstrain genetic differences that create a powerful resource for studying the regulation of IOP. Age, time of day, obesity and diabetes have effects on mouse IOP similar to those in humans and other species. Mutations in two of the assessed candidate genes (Lepr and Tyr result in increased IOP. These studies demonstrate that mice are a practical and powerful experimental system to study the genetics of IOP regulation and disease processes that raise IOP to harmful levels.

  13. The correlation between body mass index and intraocular pressure in children

    Directory of Open Access Journals (Sweden)

    Luciano Lira de Albuquerque

    2013-02-01

    Full Text Available PURPOSE: There is evidence from some studies that support an association between obesity in adults and higher intraocular pressure (IOP. However, this association has not been completely studied in children. Our aim is to evaluate the association between child body mass index (BMI and IOP. METHODS: Ninety-six children attending the Instituto de Medicina Integral Prof. Fernando Figueira (IMIP in Brazil were studied. Thirty-three were overweight/obese with a mean BMI of 29.7 ± 5.2 and 63 with a mean BMI of 20.8 ± 3.3. IOP was measured using the Goldmann applanation tonometer and was corrected for corneal thickness. The coefficient of correlation between BMI and IOP was calculated. RESULTS: There was no significant difference in the IOP of children with or without overweight/obesity. The mean IOP was 13.5 and 13.0 mmHg for the right eye and 13.1 and 12.9 mmHg for left eye, respectively (p=0.38 and p=0.71. The results remained the same after correction by pachymetry; 13.0 and 13.1 mmHg for the right eye and 12.4 and 12.9 mmHg for the left eye, respectively (p=0.88 and p=0.41. The coefficient of correlation between BMI and IOP was 0.070 (p=0.496. CONCLUSION: These results do not show a correlation between body mass index and IOP in children. Further studies are warranted to clarify the association between BMI and IOP in children.

  14. One-day postoperative intraocular pressure spikes after phacoemulsification cataract surgery in patients taking tamsulosin.

    Science.gov (United States)

    Bonnell, Levi N; SooHoo, Jeffrey R; Seibold, Leonard K; Lynch, Anne M; Wagner, Brandie D; Davidson, Richard S; Taravella, Michael J

    2016-12-01

    To evaluate the relationship between 1-day postoperative intraocular pressure (IOP) after phacoemulsification cataract surgery and tamsulosin use. University of Colorado Health Eye Center, Aurora, Colorado, USA. Retrospective cohort study. Registry data from men who had cataract surgery were used. Patients taking tamsulosin at the time of surgery were included as cases, while patients with no history of tamsulosin use were used as controls. The primary outcome was a 1-day postoperative IOP spike defined as an IOP increase greater than 10 mm Hg compared with baseline or a 1-day postoperative IOP of 30 mm Hg or higher. General estimating equations were used for analysis. The study comprised 584 men (864 eyes). An IOP increase greater than 10 mm Hg or IOP 30 mm Hg or higher after cataract surgery occurred in 12.4% and 9.3%, respectively, of eyes in the tamsulosin group versus 4.4% and 2.1%, respectively, in the control group (all P = .001). After adjusting for significant covariates, patients on tamsulosin were 2.6 times (95% confidence interval [CI], 1.2-5.7; P = .01] and 3.8 (95% CI, 1.3-10.9; P = .01) more likely to have a 1-day postoperative IOP increase greater than 10 mm Hg or a 1-day postoperative IOP of 30 mm Hg or higher. Patients on tamsulosin had an increased risk of a 1-day postoperative IOP spike after cataract surgery, showing the importance of identifying patients on tamsulosin preoperatively to better manage and potentially mitigate IOP spikes. None of the authors has a financial or proprietary interest in any material or method mentioned. Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  15. Ocular biometric parameters associated with intraocular pressure reduction after cataract surgery in normal eyes.

    Science.gov (United States)

    Yang, Hyun Seung; Lee, Junsung; Choi, Sangkyung

    2013-07-01

    To evaluate the ocular biometric parameters associated with intraocular pressure (IOP) reduction after phacoemulsification. Prospective, observational case series. The study included 999 patients who had undergone uncomplicated phacoemulsification. IOP and ocular biometric parameters were checked preoperatively and 3 months postoperatively using anterior segment optical coherence tomography, optical biometry, and ultrasonic biomicroscopy. The relationship between IOP change and the parameters, including preoperative IOP, anterior chamber depth, axial length, angle opening distance at 500 μm, anterior chamber area, corneal thickness, lens thickness, and iris thickness at 750 μm, was evaluated. The mean patient age was 67.1 ± 4.3 years. The average change in IOP was -1.6 mm Hg (-11.8%). In univariate analysis, axial length, corneal thickness, and iris thickness were not significantly associated with IOP reduction. However, preoperative IOP, anterior chamber depth, angle opening distance, anterior chamber area, and lens thickness were significantly associated with IOP change (P < .05). Furthermore, changes in anterior chamber depth (standardized coefficient beta [B] = -0.082), angle opening distance (B = -0.095), and anterior chamber area (B = -0.380) were more strongly correlated with IOP change than were preoperative factors (B = -0.078, B = -0.071, and B = -0.067, respectively). In multivariate analysis, preoperative IOP, lens thickness, angle opening distance change, and anterior chamber area change were significantly associated with IOP change (P < .005). In addition to preoperative IOP and lens thickness, parameters such as changes in anterior chamber area and angle opening distance were significantly associated positively with reduced IOP after phacoemulsification. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. Optic Nerve Head Drusen: The Relationship Between Intraocular Pressure and Optic Nerve Structure and Function.

    Science.gov (United States)

    Nolan, Kaitlyn W; Lee, Michael S; Jalalizadeh, Rohan A; Firl, Kevin C; Van Stavern, Gregory P; McClelland, Collin M

    2017-11-09

    To determine whether at the time of diagnosis, the intraocular pressure (IOP) in patients with optic nerve head drusen (ONHD) correlates with the perimetric mean deviation (PMD) and the mean retinal nerve fiber layer (RNFL) thickness on optical coherence tomography (OCT). This retrospective chart review included adults with ONHD from 2 academic medical centers. Inclusion criteria were age older than 18 years, definitive diagnosis of ONHD, measurement of IOP, and an automated visual field (VF) within 3 months of diagnosis. Exclusion criteria were unreliable VFs, use of IOP-lowering therapy, and visually significant ocular comorbidities. Data were collected from the initial visit. Age, IOP, method of diagnosis of ONHD, mean RNFL thickness, and PMD were recorded. Multiple and logistic regression models were used to control for potential confounders in statistical analyses. Chart review identified 623 patients, of which 146 patients met inclusion criteria. Mean age was 44.2 years (range: 19-82 years). Average PMD of 236 eyes was -5.22 dB (range, -31.2 to +1.21 dB). Mean IOP was 15.7 mm Hg (range: 6-24 mm Hg). Forty eyes (16.9%) underwent RNFL measurement using OCT; mean RNFL thickness was 79.9 μm (range: 43-117 μm). There was no statistically significant association between IOP and PMD (P = 0.13) or RNFL thickness (P = 0.65). Eyes with ocular hypertension tended to have less depressed PMD than those without (P= 0.031). Stratified analyses of visible and buried subgroups yielded similar results. Lowering IOP in patients with ONHD has been proposed as a means to prevent progression of optic neuropathy. Our study demonstrated that among predominately normotensive eyes, higher IOP was not associated with greater VF loss or thinner RNFL at the time of presentation. This suggests that lowering IOP may not be beneficial in preventing visual loss in normotensive eyes with ONHD.

  17. Central corneal thickness and intraocular pressure in captive black-footed penguins (Spheniscus dermersus).

    Science.gov (United States)

    Gonzalez-Alonso-Alegre, Elisa M; Martinez-Nevado, Eva; Caro-Vadillo, Alicia; Rodriguez-Alvaro, Alfonso

    2015-01-01

    To determine the central corneal thickness (CCT) by ultrasonic pachymetry and the effect of these values on the measurements of intraocular pressures (IOP) with rebound tonometry (TonoVet(®) ) in a captive flock of black-footed penguins (Spheniscus dermersus). Variations in CCT by age and weight, and variations in IOP by age were compared. Both eyes of 18 clinically normal black-footed penguins (Spheniscus dermersus) were used. The IOP was measured by the TonoVet(®) in both eyes of all the penguins. CTT measurements were performed 5 min later in all eyes using an ultrasound pachymeter. The mean IOP values ± SD were 31.77 ± 3.3 mm Hg (range of mean value: 24-38). The mean CCT values were 384.08 ± 30.9 μm (range of mean value: 319-454). There was no correlation between IOP and CCT values (P = 0.125). There was no difference in CCT measurements by age (P = 0.122) or weight (P = 0.779). A correlation was observed (P = 0.032) between IOP values and age. The coefficient of correlation was negative (ρ = -0.207). Ultrasound pachymetry has shown to be a reliable and easy technique to measure CCT in penguins. No correlation was observed between IOP and CCT values in this study. IOP showed a significant but weak decrease as age increased in the black-footed penguin. © 2014 American College of Veterinary Ophthalmologists.

  18. Changes in intraocular pressure and anterior segment morphometry after uneventful phacoemulsification cataract surgery.

    LENUS (Irish Health Repository)

    Dooley, I

    2012-02-01

    PURPOSE: To study changes in anterior segment morphometry after uneventful phacoemulsification cataract surgery, and to investigate whether there is a relationship between any observed changes and intraocular pressure (IOP) reduction after the procedure. METHODS: The anterior chamber depth (ACD), anterior chamber volume (ACV), anterior chamber angle (ACA), central corneal thickness (CCT), and IOP were measured in 101 non-glaucomatous eyes before and after uneventful phacoemulsification cataract surgery. RESULTS: After cataract surgery, the mean ACD, ACV, and ACA values increased by 1.08 mm, 54.4 mm(3), and 13.1 degrees , respectively, and the mean IOP (corrected for CCT) decreased by 3.2 mm Hg. The predictive value of a previously described index (preoperative ACD\\/preoperative IOP (corrected for CCT) or CPD ratio) for IOP (corrected for CCT) reduction after cataract surgery was confirmed, reflected in an r(2) value of 23.3% between these two parameters (P<0.001). Other indices predictive of IOP reduction after cataract surgery were also identified, including preoperative IOP\\/preoperative ACV and preoperative IOP\\/preoperative ACA, reflected in r(2) values of 13.7 and 13.7%, respectively (P<0.001 and P<0.001, respectively). CONCLUSIONS: Our study confirms the predictive value of the CPD ratio for IOP reduction after cataract surgery, and may contribute to the decision-making process in patients with glaucoma or ocular hypertension. Furthermore, two novel indices of preoperative parameters that are predictive for IOP reduction after cataract surgery were identified, and enhance our understanding of the mechanisms underlying IOP changes after this procedure.

  19. Relationship between intraocular pressure and angle configuration: an anterior segment OCT study.

    Science.gov (United States)

    Chong, Rachel S; Sakata, Lisandro M; Narayanaswamy, Arun K; Ho, Sue-Wei; He, Mingguang; Baskaran, Mani; Wong, Tien Yin; Perera, Shamira A; Aung, Tin

    2013-03-05

    To assess the relationship between intraocular pressure (IOP) and anterior chamber angle (ACA) configuration as assessed by gonioscopy and anterior segment optical coherence tomography (AS-OCT). A total of 2045 subjects aged 50 years and older, were recruited from a community clinic and underwent AS-OCT, Goldmann applanation tonometry, and gonioscopy. A quadrant was classified as closed on gonioscopy if the posterior trabecular meshwork could not be seen. A closed quadrant on AS-OCT was defined by the presence of any contact between the iris and angle wall anterior to the scleral spur. Customized software (Zhongshan Angle Assessment Program, Guangzhou, China) was used to measure AS-OCT parameters on AS-OCT scans, including anterior chamber depth, area, and volume; iris thickness (IT) and curvature; lens vault; angle opening distance; and trabecular-iris space area. IOP values were adjusted for age, sex, diabetes and hypertension status, body mass index, central corneal thickness, and presence of peripheral anterior synechiae. Mean age of study subjects was 63.2 ± 8.0 years, 52.6% were female, and 89.4% were Chinese. Mean IOP was 14.8 ± 2.4 mm Hg (range 826). IOP (mean ± SE) increased with number of quadrants with gonioscopic angle closure (none: 14.6 ± 0.2; one: 14.7 ± 0.3; two: 15.0 ± 0.3; three: 15.0 ± 0.3; four: 15.6 ± 0.3 mm Hg; P measured on AS-OCT images, except for IT and lens vault. There was an association between the extent of angle closure, as assessed on AS-OCT and gonioscopy, with increasing IOP.

  20. Tear production and intraocular pressure in canine eyes with corneal ulceration

    Directory of Open Access Journals (Sweden)

    David L. Williams

    2017-05-01

    Full Text Available This study aimed to evaluate changes in lacrimation and intraocular pressure (IOP in dogs with unilateral corneal ulceration using the Schirmer tear test (STT and rebound (TonoVet® tonometry. IOP and STT values were recorded in both ulcerated and non-ulcerated (control eyes of 100 dogs diagnosed with unilateral corneal ulceration. Dogs presented with other ocular conditions as their primary complaint were excluded from this study. The mean ± standard deviation for STT values in the ulcerated and control eyes were 20.2±4.6 mm/min and 16.7±3.5 mm/min respectively. The mean ± standard deviation for IOP in the ulcerated and control eyes were 11.9±3.1 mmHg and 16.7±2.6 mmHg respectively. STT values were significantly higher (p<0.000001 in the ulcerated eye compared to the control eye while IOP was significantly lower (p<0.0001. There is an increase in lacrimation and a decrease in IOP in canine eyes with corneal ulceration. The higher tear production in ulcerated eyes shows the importance of measuring STT in both eyes in cases of corneal ulceration, since this increased lacrimation may mask an underlying keratoconjunctivitis sicca only evident in the contralateral eye. The lower IOP in ulcerated eyes is likely to relate to mild uveitic change in the ulcerated eye with a concomitant increase in uveoscleral aqueous drainage. While these changes in tear production and IOP in ulcerated eyes are widely recognised in both human and veterinary ophthalmology, it appears that this is the first controlled documented report of these changes in a large number of individuals.

  1. System for Rapid, Precise Modulation of Intraocular Pressure, toward Minimally-Invasive In Vivo Measurement of Intracranial Pressure.

    Directory of Open Access Journals (Sweden)

    Max A Stockslager

    Full Text Available Pathologic changes in intracranial pressure (ICP are commonly observed in a variety of medical conditions, including traumatic brain injury, stroke, brain tumors, and glaucoma. However, current ICP measurement techniques are invasive, requiring a lumbar puncture or surgical insertion of a cannula into the cerebrospinal fluid (CSF-filled ventricles of the brain. A potential alternative approach to ICP measurement leverages the unique anatomy of the central retinal vein, which is exposed to both intraocular pressure (IOP and ICP as it travels inside the eye and through the optic nerve; manipulating IOP while observing changes in the natural pulsations of the central retinal vein could potentially provide an accurate, indirect measure of ICP. As a step toward implementing this technique, we describe the design, fabrication, and characterization of a system that is capable of manipulating IOP in vivo with <0.1 mmHg resolution and settling times less than 2 seconds. In vitro tests were carried out to characterize system performance. Then, as a proof of concept, we used the system to manipulate IOP in tree shrews (Tupaia belangeri while video of the retinal vessels was recorded and the caliber of a selected vein was quantified. Modulating IOP using our system elicited a rapid change in the appearance of the retinal vein of interest: IOP was lowered from 10 to 3 mmHg, and retinal vein caliber sharply increased as IOP decreased from 7 to 5 mmHg. Another important feature of this technology is its capability to measure ocular compliance and outflow facility in vivo, as demonstrated in tree shrews. Collectively, these proof-of-concept demonstrations support the utility of this system to manipulate IOP for a variety of useful applications in ocular biomechanics, and provide a framework for further study of the mechanisms of retinal venous pulsation.

  2. Cerebral perfusion pressure in women with preeclampsia is elevated even after treatment of elevated blood pressure.

    Science.gov (United States)

    Sonneveld, Milan J; Brussé, Ingrid A; Duvekot, Johannes J; Steegers, Eric A P; Grune, Frank; Visser, Gerhard H

    2014-05-01

    Cerebral perfusion pressure (CPP) is elevated in preeclampsia, and may predispose to cerebrovascular complications and progression to eclampsia. We estimated zero flow pressure (ZFP) and CPP using simultaneously obtained arterial blood pressure and middle cerebral artery blood flow velocity in 10 women with preeclampsia, all treated with methyldopa with or without nifedipine, and 18 healthy pregnant controls. Mean ± SD ZFP was lower in women with preeclampsia than in controls (16.8 ± 10.9 vs. 31.7 ± 15.0 mmHg, p = 0.01) whereas CPP was considerably higher (82.3 ± 17.7 vs. 55.0 ± 11.7 mmHg, p preeclampsia, but not in controls. Women with preeclampsia may have an increased cerebral perfusion due to a reduced ZFP and increased CPP despite treatment with antihypertensive medication. More rigorous antihypertensive therapy, aimed at reducing CPP, could result in a decrease in cerebral complications in women with preeclampsia. © 2014 Nordic Federation of Societies of Obstetrics and Gynecology.

  3. Intracranial pressure (ICP) and optic nerve subarachnoid space pressure (ONSP) correlation in the optic nerve chamber: the Beijing Intracranial and Intraocular Pressure (iCOP) study.

    Science.gov (United States)

    Hou, Ruowu; Zhang, Zheng; Yang, Diya; Wang, Huaizhou; Chen, Weiwei; Li, Zhen; Sang, Jinghong; Liu, Sumeng; Cao, Yiwen; Xie, Xiaobin; Ren, Ruojin; Zhang, Yazhuo; Sabel, Bernhard A; Wang, Ningli

    2016-03-15

    Because a lowered intracranial pressure (ICP) is a possible mechanism of optic neuropathy, we wished to study the CSF dynamics in the optic nerve chamber by recording possible changes in the optic nerve subarachnoid space pressure (ONSP) and the impact on it when acutely lowering ICP. In eight normal dogs pressure probes were implanted in the left brain ventricle, lumbar cistern, optic nerve subarachnoid space and in the anterior eye chamber. Following CSF shunting from the brain ventricle we monitored changes of ICP, lumbar cistern pressure (LCP), ONSP and intraocular pressure (IOP). At baseline, the pressures were different with ICP>LCP>ONSP but correlated with each other (PICP (PICP gradually decreased in a linear fashion together with the ONSP ("ICP-depended zone"). But when the ICP fell below a critical breakpoint, ICP and ONSP became uncoupled and ONSP remained constant despite further ICP decline ("ICP-independent zone"). Because the parallel decline of ICP and ONSP breaks down when ICP decreases below a critical breakpoint, we interpret this as a sign of CSF communication arrest between the intracranial and optic nerve SAS. This may be caused by obstructions of either CSF inflow through the optic canal or outflow into the intra-orbital cavity. This CSF exchange arrest may be a contributing factor to optic nerve damage and the optic nerve chamber syndrome which may influence the loss of vision or its restoration. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Is glycine effective against elevated blood pressure?

    Science.gov (United States)

    El Hafidi, Mohammed; Pérez, Israel; Baños, Guadalupe

    2006-01-01

    Glycine, a non-essential amino acid, has been found to protect against oxidative stress in several pathological situations, and it is required for the biosynthesis of structural proteins such as elastin. As hypertension is a disease in which free radicals and large vessel elasticity are involved, this article will examine the possible mechanisms by which glycine may protect against high blood pressure. The addition of glycine to the diet reduces high blood pressure in a rat model of the metabolic syndrome. Also, glycine supplemented to the low protein diet of rat dams during pregnancy has a beneficial effect on blood pressure in their offspring. The mechanism by which glycine decreases high blood pressure can be attributed to its participation in the reduction of the generation of free radicals, increasing the availability of nitric oxide. In addition, as glycine is required for a number of critical metabolic pathways, such as the synthesis of the structural proteins collagen and elastin, the perturbation of these leads to impaired elastin formation in the aorta. This involves changes in the aorta's elastic properties, which would contribute to the development of hypertension. The use of glycine to lower high blood pressure could have a significant clinical impact in patients with the metabolic syndrome and with limited resources. On the other hand, more studies are needed to explore the beneficial effect of glycine in other models of hypertension and to investigate possible side-effects of treatment with glycine.

  5. Digoxin derivatives with selectivity for the α2β3 isoform of Na,K-ATPase potently reduce intraocular pressure.

    Science.gov (United States)

    Katz, Adriana; Tal, Daniel M; Heller, Dan; Habeck, Michael; Ben Zeev, Efrat; Rabah, Bilal; Bar Kana, Yaniv; Marcovich, Arie L; Karlish, Steven J D

    2015-11-03

    The ciliary epithelium in the eye consists of pigmented epithelial cells that express the α1β1 isoform of Na,K-ATPase and nonpigmented epithelial cells that express mainly the α2β3 isoform. In principle, a Na,K-ATPase inhibitor with selectivity for α2β3 that penetrates the cornea could effectively reduce intraocular pressure, with minimal systemic or local toxicity. We have recently synthesized perhydro-1,4-oxazepine derivatives of digoxin by NaIO4 oxidation of the third digitoxose and reductive amination with various R-NH2 substituents and identified derivatives with significant selectivity for human α2β1 over α1β1 (up to 7.5-fold). When applied topically, the most α2-selective derivatives effectively prevented or reversed pharmacologically raised intraocular pressure in rabbits. A recent structure of Na,K-ATPase, with bound digoxin, shows the third digitoxose approaching one residue in the β1 subunit, Gln84, suggesting a role for β in digoxin binding. Gln84 in β1 is replaced by Val88 in β3. Assuming that alkyl substituents might interact with β3Val88, we synthesized perhydro-1,4-oxazepine derivatives of digoxin with diverse alkyl substituents. The methylcyclopropyl and cyclobutyl derivatives are strongly selective for α2β3 over α1β1 (22-33-fold respectively), as determined either with purified human isoform proteins or intact bovine nonpigmented epithelium cells. When applied topically on rabbit eyes, these derivatives potently reduce both pharmacologically raised and basal intraocular pressure. The cyclobutyl derivative is more efficient than Latanoprost, the most widely used glaucoma drug. Thus, the conclusion is that α2β3-selective digoxin derivatives effectively penetrate the cornea and inhibit the Na,K-ATPase, hence reducing aqueous humor production. The new digoxin derivatives may have potential for glaucoma drug therapy.

  6. Survey of ophthalmic anterior segment findings and intraocular pressure in 95 North American box turtles (Terrapene spp.).

    Science.gov (United States)

    Espinheira Gomes, Filipe; Brandão, João; Sumner, Julia; Kearney, Michael; Freitas, Inês; Johnson, James; Cutler, Daniel; Nevarez, Javier

    2016-03-01

    To describe the ophthalmic biomicroscopy findings and intraocular pressures (IOP) in a captive population of box turtles and to determine whether a relationship exists between body morphometrics or health status and IOP. Hundred and three box turtles (69 Gulf coast, 24 three-toed, one ornate, one eastern, and eight unidentified) were triaged into three different color-coded groups: green (healthy), yellow (abnormal physical examination with no need for immediate care), and red (immediate care required). Both eyes were evaluated by rebound tonometry and slit-lamp biomicroscopy. Body weight and morphometric data were recorded. Intraocular pressures measurements were available for 190 eyes, slit-lamp biomicroscopy was available for 170 eyes, and morphometric data were available for 81 turtles. IOP in Gulf coast turtles (138 eyes) was 6.7 ± 1.4 mmHg OU. IOP in three-toed turtles (48 eyes) was 8.3 ± 1.5 mmHg OU, which was significantly higher than in Gulf coast turtles (P turtles only. There was a mild negative correlation between morphometrics and IOP in Gulf coast and three-toed turtles. Fifteen of 87 turtles had unilateral corneal or lenticular opacities; 3/87 had bilateral corneal or lenticular disease; and 3/87 had adnexal abnormalities. Different subspecies of box turtles have different normal intraocular pressures as measured by rebound tonometry, which was influenced by the animals' health status in one subspecies. Some morphometric parameters were found to be associated with IOP. Box turtles are often affected with ophthalmic abnormalities of unknown clinical significance. © 2015 American College of Veterinary Ophthalmologists.

  7. Decomposition reactions in RDX at elevated temperatures and pressures

    Science.gov (United States)

    Schweigert, Igor

    2015-03-01

    Mechanisms and rates of elementary reactions controlling condensed-phase decomposition of RDX under elevated temperatures (up to 2000 K) and pressures (up to a few GPa) are not known. Global decomposition kinetics in RDX below 700 K has been measured; however, the observed global pathways result from complex manifolds of elementary reactions and are likely to be altered by elevated temperatures. Elevated pressures can further affect the condensed-phase kinetics and compete with elevated temperatures in promoting some elementary reactions and suppressing others. This presentation will describe density functional theory (DFT) based molecular dynamics simulations of crystalline and molten RDX aimed to delineate the effects of elevated temperatures and pressures on the mechanism of initial dissociation and the resulting secondary reactions. This work was supported by the Naval Research Laboratory, by the Office of Naval Research, and by the DOD High Performance Computing Modernization Program Software Application Institute for Multiscale Reactive Modeling of Insensitive Munitions.

  8. CLINICAL PRESENTATION OF LENS INDUCED GLAUCOMA: STUDY OF EPIDEMIOLOGY, DURATION OF SYMPTOMS, INTRAOCULAR PRESSURE AND VISUAL ACUITY

    Directory of Open Access Journals (Sweden)

    Venkataratnam

    2015-10-01

    Full Text Available BACKGROUND: Lens Induced Glaucoma is a common cause of ocular morbidity. OBJECTIVES: Our study was to know the Epidemiological factors, Duration of Symptoms, Visual Acuity and Intraocular Pressure in the clinical Presentation of Lens Induced Glaucoma. MATERIALS AND METHODS : This w as a tertiary hospital based prospective study in the department of Glaucoma, Sarojini Devi Eye Hospital and Regional Institute of Ophthalmology (RIO, Osmania Medical College, Hyderabad over a period from March 2015 to August 2015. 50 Patients clinically diagnosed as Lens Induced Glaucoma (LIG were studied with the data of Age, Sex, literacy, Laterality and Rural / Urban status with the duration of symptoms, Intraocular pressure and Visual Acuity. The data was analyzed by simple statistical methods. RESULT S: 50 patients, clinically diagnosed as Lens Induced Glaucoma (LIG were studied. Age group distribution was 1(2.0% in 40 - 50yrs, 13 ( 26.0% in >50 - 60yrs, 26(52.0% in >60 - 70yrs and 10(20.0% in > 70 yrs. Sex distribution was 23(46.0% of Males and 27(54.0% of Females. Urban / Rural status was 15(30.0% of Urban and 35(70.0% of Rural. Literacy status was 7(14.0% of Literate and 43(86.0% of Illiterate. Laterality was RE in 24(48.0% and LE in 26(52.0%. Duration of the presenting symptoms before re porting to the Hospital was 12.0% in 2wks. Intraocular pressure (IOP in mm of Hg showed no case (0.0% in 20 – 40, 27(54.0% in >40 - 60 and 5(10.0% >60 wit h the Mean IOP of 42.12 mm of Hg. Visual Acuity (VA was PL +ve in 24(48.0 and HM - 3/60. CONCLUSIONS: Increasing age, female gender, rural, illiterate, and delayed reporting to the hospital after the pre senting symptoms were the common risk factors with increased Intraocular pressure and poor visual acuity in the clinical presentation of Lens induced Glaucoma.

  9. The Association of Central corneal thickness with Intra-ocular Pressure and Refractive Error in a Nigerian Population

    OpenAIRE

    Iyamu, Eghosasere; Memeh, Misan

    2008-01-01

    The purpose of this study was to determine the variation of central corneal thickness (CCT) with intraocular pressure (IOP) and spherical equivalent refractive error. A total of thirty-nine (N=39) subjects within 20-75 years with mean age 45.2 ± 15.4 years were used for this study. The central corneal thickness was assessed with the Corneo-Gage plus ultrasonic Pachymeter, the IOP with slit-lamp mounted Goldmann applanation tonometer and refractive status by Protec 2000 autorefractor, phoropte...

  10. Differential Intraocular Pressure Measurements by Tonometry and Direct Cannulation After Treatment with Soluble Adenylyl Cyclase Inhibitors.

    Science.gov (United States)

    Gandhi, Jarel K; Roy Chowdhury, Uttio; Manzar, Zahid; Buck, Jochen; Levin, Lonny R; Fautsch, Michael P; Marmorstein, Alan D

    2017-10-01

    To validate the increase in intraocular pressure (IOP) caused by soluble adenylyl cyclase (sAC) inhibitors and determine reasons behind variation in IOP measurements performed by tonometry. C57BL/6J mice were administered DMSO solubilized sAC inhibitors (KH7 or LRE-1) by intraperitoneal injection. Two hours post-treatment, mice were anesthetized with avertin or ketamine/xylazine/acepromazine (KXA). IOP was measured by a rebound tonometer or direct cannulation of the anterior chamber. Spectral-domain optical coherence tomography was used to measure anterior chamber depth and corneal thickness in live mice. Outflow facility was measured in perfused, enucleated mouse eyes. Compared with DMSO controls, KH7 treatment caused an increased IOP in avertin- and KXA-anesthetized mice when measured by direct cannulation [avertin: 14.4 ± 2.1 mmHg vs. 11.1 ± 1.0 mmHg (P = 0.003); KXA: 14.4 ± 1.0 mmHg vs. 11.3 ± 0.8 mmHg (P < 0.001)] and tonometry [avertin: 10.8 ± 1.4 mmHg vs. 7.4 ± 0.6 mmHg (P < 0.001); KXA: 11.9 ± 0.9 mmHg vs. 10.3 ± 1.7 mmHg (P = 0.283)]. However, treatment with KH7 in nonanesthetized mice showed a significant decrease in IOP measured by tonometry and compared with DMSO-treated animals [13.1 ± 2.6 mmHg vs. 15.6 ± 0.5 mmHg (P = 0.003)]. Both KH7- and DMSO-treated groups anesthetized with avertin showed increased corneal thickness, whereas KH7-treated mice anesthetized with KXA exhibited a shallower anterior chamber compared with untreated mice. KH7 decreased outflow facility by 85.1% in nonanesthetized, enucleated eyes (P < 0.003). Systemically administered DMSO and anesthesia have significant effects on anterior chamber characteristics, resulting in altered IOP readings measured by tonometry. In the presence of DMSO and anesthesia, tonometry IOP readings should be confirmed with direct cannulation.

  11. Comparison of Scleral Tono-Pen Intraocular Pressure Measurements with Goldmann Applanation Tonometry.

    Science.gov (United States)

    Badakere, Swathi Vallabh; Choudhari, Nikhil S; Rao, Harsha L; Chary, C Raghava; Garudadri, Chandra Sekhar; Senthil, Sirisha

    2018-02-01

    Measuring the intraocular pressure (IOP) on the sclera can be an alternative to conventional corneal measurement in eyes with scarred corneas. However, these measurements have to be evaluated prior in normal eyes. Our study aimed to evaluate scleral IOP using Tono-Pen and compared it with corneal Goldmann applanation measurements. The aim of this study was to evaluate the ability of limbal and scleral Tono-Pen IOP readings to predict central corneal Goldmann applanation tonometry (GAT) readings in eyes with normal corneas. In a cross-sectional study, 115 eyes of 115 patients attending a tertiary eye care center underwent GAT on the central cornea followed by Tono-Pen readings at the central cornea, at the limbus, and at the sclera. Bland-Altman plots were used to determine the agreement between different methods of IOP measurement. The median IOP (interquartile range) by GAT performed on the central cornea was 18 (16, 24) mmHg, and the IOP ranged from 10 to 54 mmHg. The median IOPs (interquartile range) by Tono-Pen obtained at central cornea, limbus, and sclera were 16 (13, 23), 23 (17, 28), and 33 (27, 44) mmHg, respectively. The Pearson correlation coefficient and the 95% limits of agreement between GAT readings and Tono-Pen readings at the central cornea were 0.9 (P < .001) and -4.9 to 8.74 mmHg, respectively. The correlation coefficient between GAT readings and Tono-Pen readings at the limbus and GAT readings and Tono-Pen readings at the sclera was 0.46 (P < .001) and 0.23 (P = .01), respectively. The 95% limits of agreement between these pairs of readings were -20.55 to 13.66 and -44.02 to 13.37 mmHg, respectively. This study showed limited ability of Tono-Pen readings obtained at the limbus and sclera to predict the central corneal GAT IOP readings in eyes with normal corneas at various IOP ranges.

  12. Predictors of additional intraocular pressure reduction in patients changed to latanoprost/timolol fixed combination

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    Nordmann Jean-Philippe

    2010-03-01

    Full Text Available Abstract Background Given the growing number of ocular hypotensive medications available, it is important to be able to predict a positive response to therapy. The purpose of the present study was to identify predictors of an additional 10% intraocular pressure (IOP reduction after 12 weeks of treatment with latanoprost/timolol fixed combination (FC in patients requiring a change in their previous ocular hypotensive medication. Methods This multicenter, open-label, prospective, phase IIIb study included subjects ≥18 years of age with open-angle glaucoma (OAG or ocular hypertension (OHT. Eligible subjects had baseline IOP ≥21 mmHg and insufficient response to current beta-blocker monotherapy. The primary efficacy analysis (logistic regression identified predictors of a positive response after 12 weeks of latanoprost/timolol FC. Results The intent-to-treat (ITT population included 383 subjects treated with ≥1 drop of FC and having ≥1 follow-up IOP assessment. Mean IOP was 22.19 ± 2.16 mmHg at baseline and was reduced by 5.42 ± 2.71 mmHg at study end. In all, 325 (84.9% subjects had a positive response to latanoprost/timolol FC; the response rate was similar across groups: OAG (n = 208; 82.7%; OHT (n = 161; 87.6%; OAG+OHT (n = 14; 85.7%. Higher baseline IOP (odds ratio: 1.284; 95% confidence interval [CI]: 1.101, 1.497; p = 0.0014 and absence of adverse events (odds ratio: 0.318; 95% CI: 0.161, 0.629; p = 0.0010 were significant predictors of positive response. Age, gender, ethnic origin, diagnosis, family history of OAG/OHT, corneal thickness, and concomitant systemic beta-blocker were not significant predictors of a positive response in the ITT analysis. The FC was well tolerated. The most common adverse events were related to the eye and were consistent with known adverse events associated with latanoprost and timolol. Conclusions These results support the use of latanoprost/timolol FC in patients whose IOP is insufficiently controlled

  13. Reduction on OFF-responses of Electroretinogram in Monkeys with Long-term High Intraocular Pressure.

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    Liu, Ke-Gao; Peng, Xiao-Yan; Zhang, Zheng; Sun, Hua; Yang, Di-Ya; Wang, Ning-Li

    2017-11-20

    There are ON- and OFF-pathways in the normal vertebrate retina. Short- and long-flash electroretinogram (ERG) are suitable methods to observe the function of ON- and OFF-pathways in vivo, respectively. It is clear that high intraocular pressure (IOP) might cause dysfunction of cone-dominated photopic negative response (PhNR) in monkeys with high IOP in ON-pathway. However, whether cone-dominated OFF-responses are also affected is less known. The aim of this study was to observe photopic OFF-responses of ERG in monkeys with high IOP. Nine monkeys were involved in the experiment from January 2006 to December 2016. High IOP was induced in the right eye by laser coagulation of the mid-trabecular meshwork in five monkeys. Six years after the laser coagulation, both short- and long-flash of the photopic ERG were recorded. Stimulus light was red flashes superimposed on a blue background. Four normal monkeys were examined under the same ERG protocols as controls. Paired t- test was used to compare the difference of each ERG parameter between the lasered eye and the fellow eye. Analysis of variance (ANOVA) with Tukey adjustment was adopted to calculate the differences among the lasered eye, the fellow eye, and the eyes of normal monkeys. The mean amplitude of a-wave (11.73 ± 2.05) and PhNR (8.67 ± 2.44) in lasered eyes was significantly lower than that of a-wave (21.47 ± 3.15) and PhNR (22.05 ± 3.42) in fellow eyes (P = 0.03 and P = 0.01, respectively) in response to short flash. The mean amplitude of d-wave (1.60 ± 0.59) and i-wave (3.13 ± 0.64) was significantly reduced in the lasered eyes than that of d-wave (4.01 ± 0.56) and i-wave (8.79 ± 1.75) in the fellow eyes (P = 0.02 and P = 0.02, respectively) in response to long flash. Reduced OFF-responses are recorded in monkeys with high IOP when dysfunction of photoreceptor is involved. The reduced OFF-responses to long-flash stimulus show evidence of anomalous retinal circuitry in glaucomatous retinopathy.

  14. Effect of prolonged supine position on the intraocular pressure in patients with obstructive sleep apnea syndrome.

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    Fang, Sin Yee; Wan Abdul Halim, Wan Haslina; Mat Baki, Marina; Din, Norshamsiah Md

    2018-04-01

    Obstructive sleep apnea syndrome (OSAS) patients are at risk of glaucoma but the risk increases if they have higher intraocular pressure (IOP) while sleeping. We aim to evaluate the postural effect of upright and prolong supine positions on IOP in these patients. This is a cross-sectional study involving 27 patients with symptoms of OSAS seen at a tertiary institutional center and 25 normal controls performed between June 2015 and June 2016. All patients and controls underwent a polysomnography (PSG) test and were diagnosed with OSAS based on the apnea-hypopnea index (AHI). Patients are those with OSAS symptoms and had AHI > 5, whereas controls are staffs from the ophthalmology clinic without clinical criteria for OSAS and had PSG result of AHI < 5. IOP was measured 10 min after sitting, immediately and at 30 min on supine position and immediately after resuming sitting position. The main outcome measures were the changes in mean IOP in different positions. The increase in mean IOP when changing from sitting to supine position was significantly higher in OSAS patients in both the right eye (RE) (1.01 ± 1.14 vs 0.44 ± 0.41 mmHg, p = 0.033) and left eye (LE) (1.20 ± 1.26 vs 0.48 ± 0.62 mmHg, p = 0.044). After 30 min supine, the IOP in OSAS patients showed a further increase in IOP than controls (RE 1.20 ± 1.79 vs 0.12 ± 0.66 mmHg, p = 0.001 and LE 0.59 ± 2.00 vs 0.15 ± 0.78 mmHg, p = 0.246). Higher IOP when sitting post supine is associated with higher IOP on supine position. IOP increase is significantly more in OSAS patients on prolong supine position.

  15. Intraocular pressure and ocular pulse amplitude using dynamic contour tonometry and contact lens tonometry

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    Grus Franz-H

    2004-03-01

    Full Text Available Abstract Background The new Ocular Dynamic Contour Tonometer (DCT, investigational device supplied by SMT (Swiss Microtechnology AG, Switzerland allows simultaneous recording of intraocular pressure (IOP and ocular pulse amplitude (OPA. It was the aim of this study to compare the IOP results of this new device with Goldmann tonometry. Furthermore, IOP and OPA measured with the new slitlamp-mounted DCT were compared to the IOP and OPA measured with the hand-held SmartLens®, a gonioscopic contact lens tonometer (ODC Ophthalmic Development Company AG, Switzerland. Methods Nineteen healthy subjects were included in this study. IOP was determined by three consecutive measurements with each of the DCT, SmartLens®, and Goldmann tonometer. Furthermore, OPA was measured three times consecutively by DCT and SmartLens®. Results No difference (P = 0.09 was found between the IOP values by means of DCT (mean: 16.6 mm Hg, median: 15.33 mm Hg, SD: +/- 4.04 mm Hg and Goldmann tonometry (mean: 16.17 mm Hg, median: 15.33 mm Hg, SD: +/- 4.03 mm Hg. The IOP values of SmartLens® (mean: 20.25 mm Hg, median: 19.00 mm Hg, SD: +/- 4.96 mm Hg were significantly higher (P = 0.0008 both from Goldmann tonometry and DCT. The OPA values of the DCT (mean: 3.08 mm Hg, SD: +/- 0.92 mm Hg were significantly lower (P = 0.0003 than those obtained by SmartLens® (mean: 3.92 mm Hg, SD: +/- 0.83 mm Hg. Conclusions DCT was equivalent to Goldmann applanation tonometry in measurement of IOP in a small group of normal subjects. In contrast, SmartLens® (contact lens tonometry gave IOP readings that were significantly higher compared with Goldmann applanation tonometer readings. Both devices, DCT and SmartLens® provide the measurement of OPA which could be helpful e.g. for the management of glaucoma.

  16. Sustainability of Intraocular Pressure Reduction of Travoprost Ophthalmic Solution in Subjects with Normal Tension Glaucoma.

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    Naito, Tomoko; Okuma, Shinichi; Nagayama, Mikio; Mizoue, Shiro; Ozaki, Mineo; Namiguchi, Koji; Miyamoto, Kazuhisa; Tanito, Masaki; Yoshikawa, Keiji

    2016-03-01

    We examined the sustainability of the intraocular pressure (IOP)-lowering efficacy of travoprost (0.004%) ophthalmic solution in subjects with normal tension glaucoma (NTG). Travoprost ophthalmic solution was given once daily at 9 PM to subjects with newly diagnosed NTG or with NTG who had not received any ocular hypotensives within the previous 30 days. IOP was measured at three time points (9 AM, 1 PM, and 5 PM) at baseline and week 12 visits, and at one time point (9 AM) at week 4 and week 8 visits. Conjunctival hyperemia, superficial punctate keratopathy, and other adverse events were evaluated during the observation period. Thirty subjects (12 males and 18 females; mean age 65.6 years) from 32 subjects enrolled were included in the efficacy analysis. The mean IOPs (±standard deviation) of 16.6 ± 1.4, 15.7 ± 1.8, and 15.7 ± 2.2 mmHg at 9 AM, 1 PM, and 5 PM, respectively, at baseline reduced significantly to the mean IOPs of 13.0 ± 1.8, 12.7 ± 1.8, and 12.8 ± 1.6 mmHg, respectively, at week 12 (P < 0.0001 for every time point). Together with the mean IOPs of 13.4 ± 1.9 mmHg at week 4 and 13.2 ± 1.9 mmHg at week 8, the pooled IOP during the observation period for up to 12 weeks showed a statistically and clinically significant reduction of IOP at 9 AM. (3.4 mmHg or 20.3% reduction from baseline, P < 0.0001). There were no adverse events leading to treatment discontinuation. This multi-center collaborative study suggests that IOP-lowering efficacy of travoprost ophthalmic solution persists during the day at the clinically relevant level in subjects with NTG. Alcon Japan Ltd. University Hospital Medical Information Network, UMIN ID: 000011621.

  17. Effect of diabetes mellitus on corneal biomechanics and measurement of intraocular pressure.

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    Scheler, Annabelle; Spoerl, Eberhard; Boehm, Andreas G

    2012-09-01

      To determine whether corneal hysteresis (CH) and corneal resistance factor (CRF) are altered in diabetes and whether these parameters are related to HbA1c.   One randomly chosen eye of 35 healthy subjects and 31 patients with diabetes was examined. Patients with diabetes were divided into group 1 with HbA1c<7% (n=14) and group 2 with HbA1c≥7% (n=17). CH and CRF were measured using ocular response analyzer (ORA); central corneal thickness (CCT) using ultrasound pachymetry; increased intraocular pressure (IOP) using Goldmann tonometer (IOP(GAT) ), Pascal dynamic contour tonometer (IOPpasc), and ORA (IOPcc). As CH and CRF are dependent on IOP and CCT, they were adjusted for IOP and CCT resulting in CHcorr and CRFcorr.   Mean HbA1c was 5.44±0.46% in healthy subjects, 6.00±0.78% in diabetic group 1, 8.58±2.44% in group 2. CHcorr (p=0.071) and CRFcorr (p=0.067) were not statistically significantly different between healthy subjects and diabetic group 1, but significantly lower in healthy subjects compared to diabetic group 2 [CHcorr (p=0.031), CRFcorr (p=0.029)]. IOPpasc (p=0.012), IOPGAT (p=0.032) and HbA1c (p=0.0001) were statistically significantly different between healthy subjects and all patients with diabetes (groups 1+2), but not age, sex and CCT. Over all patients with diabetes, CHcorr (p=0.012, R2=0.197) and CRFcorr (p=0.008, R2=0.217) were correlated to HbA1c but not in healthy subjects [CHcorr (p=0.931, R2=0.0001), CRFcorr (p=0.837, R2=0.001)].   In poorly controlled diabetics, CHcorr and CRFcorr are significantly higher compared with those of the healthy subjects and patients with well-controlled diabetes. In diabetes, CHcorr and CRFcorr are correlated to HbA1c, suggesting that the biomechanical properties of the cornea are altered depending on the glucose control. © 2012 The Authors. Acta Ophthalmologica © 2012 Acta Ophthalmologica Scandinavica Foundation.

  18. Contribution of TRPV1 to microglia-derived IL-6 and NFkappaB translocation with elevated hydrostatic pressure.

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    Sappington, Rebecca M; Calkins, David J

    2008-07-01

    The authors investigated the contributions of the transient receptor potential vanilloid-1 receptor (TRPV1) and Ca(2+) to microglial IL-6 and nuclear factor kappa B (NFkappaB) translocation with elevated hydrostatic pressure. The authors first examined IL-6 colocalization with the microglia marker Iba-1 in the DBA/2 mouse model of glaucoma to establish relevance. They isolated microglia from rat retina and maintained them at ambient or elevated (+70 mm Hg) hydrostatic pressure in vitro and used ELISA and immunocytochemistry to measure changes in the IL-6 concentration and NFkappaB translocation induced by the Ca(2+) chelator EGTA, the broad-spectrum Ca(2+) channel inhibitor ruthenium red, and the TRPV1 antagonist iodo-resiniferatoxin (I-RTX). They applied the Ca(2+) dye Fluo-4 AM to measure changes in intracellular Ca(2+) at elevated pressure induced by I-RTX and confirmed TRPV1 expression in microglia using PCR and immunocytochemistry. In DBA/2 retina, elevated intraocular pressure increased microglial IL-6 in the ganglion cell layer. Elevated hydrostatic pressure (24 hours) increased microglial IL-6 release, cytosolic NFkappaB, and NFkappaB translocation in vitro. These effects were reduced substantially by EGTA and ruthenium red. Antagonism of TRPV1 in microglia partially inhibited pressure-induced increases in IL-6 release and NFkappaB translocation. Brief elevated pressure (1 hour) induced a significant increase in microglial intracellular Ca(2+) that was partially attenuated by TRPV1 antagonism. Elevated pressure induces an influx of extracellular Ca(2+) in retinal microglia that precedes the activation of NFkappaB and the subsequent production and release of IL-6 and is at least partially dependent on the activation of TRPV1 and other ruthenium red-sensitive channels.

  19. 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

  20. A new measure of patient satisfaction with ocular hypotensive medications: The Treatment Satisfaction Survey for Intraocular Pressure (TSS-IOP

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    Stewart Jeanette A

    2003-11-01

    Full Text Available Abstract Purpose To validate the treatment-specific Treatment Satisfaction Survey for Intraocular Pressure (TSS-IOP. Methods Item content was developed by 4 heterogeneous patient focus groups (n = 32. Instrument validation involved 250 patients on ocular hypotensive medications recruited from ophthalmology practices in the Southern USA. Participants responded to demographic and test questions during a clinic visit. Standard psychometric analyses were performed on the resulting data. Sample Of the 412 patients screened, 253 consented to participate, and 250 provided complete datasets. The sample included 44% male (n = 109, 44% Black (n = 109 and 57% brown eyed (n = 142 participants, with a mean age of 64.6 years (SD 13.1 and a history of elevated IOP for an average of 8.4 yrs (SD 7.8. A majority was receiving monotherapy (60%, n = 151. Results A PC Factor analysis (w/ varimax rotation of the 31 items yielded 5 factors (Eigenvalues > 1.0 explaining 70% of the total variance. Weaker and conceptually redundant items were removed and the remaining 15 items reanalyzed. The satisfaction factors were; Eye Irritation (EI; 4 items, Convenience of Use (CofU; 3 items, Ease of Use (EofU; 3 items, Hyperemia (HYP; 3 items, and Medication Effectiveness (EFF; 2 items. Chronbach's Alphas ranged from .80 to .86. Greater distributional skew was found for less common experiences (i.e., HYP & EI with 65% & 48.4% ceilings than for more common experiences (i.e., EofU, CofU, EFF with 10.8%, 20.8% & 15.9% ceilings. TSS-IOP scales converged with conceptually related scales on a previously validated measure of treatment satisfaction, the TSQM (r = .36 to .77. Evidence of concurrent criterion-related validity was found. Patients' symptomatic ratings of eye irritation, hyperemia and difficulties using the medication correlated with satisfaction on these dimensions (r = .30-.56, all p Conclusions This study provides initial evidence that the TSS-IOP is a reliable and valid

  1. Diurnal variations in intraocular pressure and central corneal thickness and the correlation between these factors in dogs.

    Science.gov (United States)

    Garzón-Ariza, Alicia; Guisado, Alicia; Galán, Alba; Martín-Suárez, Eva

    2017-12-12

    To study the diurnal variation in intraocular pressure (IOP) and central corneal thickness (CCT) in healthy Beagles by rebound tonometry and ultrasonic pachymetry, respectively, in addition to determining whether a correlation exists between these two variables. Twenty eyes from 10 healthy Beagle dogs were included in the study. The IOP and CCT were measured by rebound tonometry and ultrasonic pachymetry, respectively, at 2-h intervals over an 8-hour period between 10:00 and 18:00. The mean values (± SD) of IOP obtained were 11.45 ± 2.96 at 10:00, 10.00 ± 1.89 at 12:00, 8.25 ± 1.62 at 14:00, 7.05 ± 1.05 at 16:00, and 6.55 ± 1.36 at 18:00. The mean values (± SD) of CCT obtained were 554.95 ± 72.41 at 10:00, 549.20 ± 69.10 at 12:00, 566.15 ± 80.56 at 14:00, 545.45 ± 70.19 at 16:00, and 538.30 ± 73.33 at 18:00. The IOP and CCT of dogs were found to decrease progressively from the first to the last measurement. There were statistically significant differences between the IOP (P = 0.000) and CCT values (P = 0.032) measured at different times of the day. There was no effect or interaction between gender and eye with the dependent variables. The IOP and CCT were found to be positively correlated (r = 0.213, P = 0.034). The regression equation demonstrated that for every 100 μm increase in CCT, there was an elevation in IOP by 0.8 mmHg. The CCT and IOP values were lower in the afternoon/evening than in the morning, and these were positively correlated. Both findings are important for the diagnostic interpretation of IOP values in dogs. © 2017 American College of Veterinary Ophthalmologists.

  2. Bimatoprost 0.03% versus brimonidine 0.2% in the prevention of intraocular pressure spike following neodymium:yttrium–aluminum–garnet laser posterior capsulotomy.

    Science.gov (United States)

    Artunay, Ozgur; Yuzbasioglu, Erdal; Unal, Mustafa; Rasier, Rifat; Sengul, Alper; Bahcecioglu, Halil

    2010-10-01

    The aim of this study was to compare the efficacy of bimatoprost 0.03% with brimonidine 0.2% in preventing intraocular pressure (IOP) elevations after neodymium:yttrium–aluminum–garnet (Nd:YAG) laser posterior capsulotomy. In this prospective, randomized, double-masked study, 195 eyes of 195 consecutive patients who had YAG laser capsulotomy for posterior capsule opacification were recruited. Eyes received either 1 drop of bimatoprost 0.03% (98 patients) or brimonidine 0.2% (97 patients) at 1h before laser surgery. A masked observer measured IOP by Goldmann applanation tonometry before treatment and after treatment at 1h, 3h, 24h, and 7 days. Inflammation was evaluated after surgery. Formation of cystoid macular edema was assessed by measuring the macular thickness before and after laser surgery. The average peak of postoperative IOP elevation was 2.2±3.9mm Hg in the bimatoprost 0.03% and 3.6±3.1mm Hg in the brimonidine 0.2% group. The difference was statistically significant (P<0.001). Postoperative IOP elevations of 10mm Hg or more occurred in 1 eye (1.56%) in the bimatoprost 0.03% group and 5 eyes (7.35%) in the brimonidine 0.2%. This difference was statistically significant (P<0.001). Macular edema and anterior chamber reaction were not observed related to bimatoprost. No clinically significant side effects were noted in either group. Our results indicate that prophylactic use of bimatoprost 0.03% is more effective than brimonidine 0.2% in preventing IOP elevation immediately after YAG laser capsulotomy. Bimatoprost 0.03% as a prostamide analog may provide new option for preventing IOP elevation after YAG laser capsulotomy.

  3. Combined ab interno trabeculotomy and lens extraction: a novel management option for combined uveitic and chronic narrow angle raised intraocular pressure.

    Science.gov (United States)

    Lin, Siying; Gupta, Bhaskar; Rossiter, Jonathan

    2016-02-01

    Minimally invasive glaucoma surgery is a developing area that has the potential to replace traditional glaucoma surgery, with its known risk profile, but at present there are no randomised controlled data to validate its use. We report on a case where sequential bilateral combined ab interno trabeculotomy and lens extraction surgery was performed on a 45-year-old woman with combined uveitic and chronic narrow angle raised intraocular pressure. Maximal medical management alone could not control the intraocular pressure. At 12-month follow-up, the patient had achieved stable intraocular pressure in both eyes on a combination of topical ocular antiglaucomatous and steroid therapies. This case demonstrates the effectiveness of trabecular meshwork ablation via ab interno trabeculotomy in a case of complex mixed mechanism glaucoma. 2016 BMJ Publishing Group Ltd.

  4. Intraocular pressure measurement after penetrating keratoplasty: minified Goldmann applanation tonometer, pneumatonometer, and Tono-Pen versus manometry.

    Science.gov (United States)

    Ménage, M J; Kaufman, P L; Croft, M A; Landay, S P

    1994-09-01

    The accuracy of intraocular pressure measurement with the minified Goldmann applanation tonometer, the pneumatonometer, and the Tono-Pen tonometer were compared in post-mortem human eyes which had undergone penetrating keratoplasty. Enucleated post-mortem human eyes underwent same sized (7.75 mm) or 0.5 mm oversized (8.25 mm) autologous penetrating keratoplasty. Intraocular pressure was then set and measured manometrically while being determined successively with each tonometer over the range of 0-65 mm Hg. Linear regression analysis comparing tonometric and manometric readings showed: (1) minified Goldmann applanation tonometer-slope 0.985 and 0.944, intercept 1.64 and 2.55 mm Hg, correlation coefficient 0.99 and 0.99 in same sized and oversized grafted eyes respectively; (2) pneumatonometer-slope 1.008 and 0.990, intercept 3.37 and 3.69 mm Hg, correlation coefficient 0.99 and 0.98; (3) Tono-Pen-slope 1.061 and 1.002, intercept 5.01 and 4.06 mm Hg, correlation coefficient 0.97 and 0.98. We concluded that the minified Goldmann applanation tonometer is as accurate or more accurate than the pneumatonometer and the Tono-Pen in post-mortem post-keratoplasty human eyes, and may be an economical, convenient alternative to the latter two instruments in clinical practice.

  5. Comparison of intraocular pressure andvault after implantation of implantable collamer lens with and without a central hole.

    Science.gov (United States)

    Chen, Haiting; Niu, Guangzeng; Fan, Yuxiang; Ma, Jingxue

    2016-11-16

    The Implantable Collamer Lens (ICL) has been used widely for refractive errors, We performed this prospective randomized comparative study to compare postoperative intraocular pressure (IOP) and vaults of the eyes implanted with conventional ICL and central hole ICL. This study evaluated 44 eyes of 22 patients who underwent central hole ICL implantation in one eye and conventional ICL implantation in the other eye by randomization assignment. noncontact intraocular pressure were performed on 6 h, 1 day, 3 days, 1 week, 2 weeks, 1 month, 3 months and 6 months, while ICL vaults were measured on 1 day, 1 week, 1 month and 6 months. The IOP of both eyeswithcentral hole and conventional ICLrosetemporarily during the first month after surgeries, especially on 1 day and 2 weeks points postoperatively. The IOP ofeyes with central hole ICL was higher than that of conventionl ICL. The vaults ofeyes with central hole and conventional ICL decreased slightly with time but did not significantly affect the postoperative IOP. Despite the sensitivity of viscoelastic agents or inflammation, this newly developed central hole ICL implantation appears to be equivalent in safty and effcacy to conventional ICL implantation for the correction of ametropia. Current Controlled Trials ChiCTR-INR-16008896 . Retrospectively registered 24 July 2016.

  6. Assessment of the Pascal dynamic contour tonometer in monitoring intraocular pressure in unoperated eyes and eyes after LASIK.

    Science.gov (United States)

    Siganos, Dimitrios S; Papastergiou, Georgios I; Moedas, Carlos

    2004-04-01

    To assess the performance of the Pascal dynamic contour tonometer (PDCT) (Swiss Microtechnology AG) by comparing it to Goldmann applanation tonometry (GAT) and noncontact air tonometry (NCT) before and after laser in situ keratomileusis (LASIK). Vlemma Eye Institute, Athens, Greece. Intraocular pressure was measured in 118 eyes before and 1 and 4 weeks after LASIK using GAT, NCT, and the PDCT, which allows direct, digital, transcorneal measurement of intraocular pressure. Preoperatively, central corneal thickness (CCT) correlated with GAT and NCT measurements but not with PDCT measurements. After LASIK, the mean reduction in CCT ranged from -3.0 to -171.0 microm (median 78 microm). The mean GAT measurement dropped by -4.9 mm Hg +/- 2.7 (SD) at 1 week and was -5.4 +/- 3.0 mm Hg at 4 weeks. Similar drops were observed in NCT measurements. The observed post-LASIK changes in GAT and NCT IOP measurements were not directly proportional to the change in CCT, refractive error, or mean keratometric readings. The preoperative and postoperative PDCT measurements did not differ significantly. The structural corneal changes induced by LASIK appeared to influence GAT and NCT measurements but not PDCT measurements. Therefore, PDCT may be better suited for monitoring IOP in unoperated eyes and in eyes that have had LASIK.

  7. Study of the Effect of Distance and Misalignment between Magnetically Coupled Coils for Wireless Power Transfer in Intraocular Pressure Measurement

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    Adrian E. Rendon-Nava

    2014-01-01

    Full Text Available An analysis of the effect of distance and alignment between two magnetically coupled coils for wireless power transfer in intraocular pressure measurement is presented. For measurement purposes, a system was fabricated consisting of an external device, which is a Maxwell-Wien bridge circuit variation, in charge of transferring energy to a biomedical implant and reading data from it. The biomedical implant is an RLC tank circuit, encapsulated by a polyimide coating. Power transfer was done by magnetic induction coupling method, by placing one of the inductors of the Maxwell-Wien bridge circuit and the inductor of the implant in close proximity. The Maxwell-Wien bridge circuit was biased with a 10 MHz sinusoidal signal. The analysis presented in this paper proves that wireless transmission of power for intraocular pressure measurement is feasible with the measurement system proposed. In order to have a proper inductive coupling link, special care must be taken when placing the two coils in proximity to avoid misalignment between them.

  8. The Effect of Altitude on Intraocular Pressure in Vitrectomized Eyes with Sulfur Hexafluoride Tamponade by the Friedenwald Method: Rabbit Animal Model

    Directory of Open Access Journals (Sweden)

    Jans Fromow-Guerra

    2016-01-01

    Full Text Available The aim of this study is to assess the change in intraocular pressure after a road trip, in eyes with different levels of filling with gas tamponade. Five rabbit eyes were subject to pars plana vitrectomy and gas tamponade (filling percentage: 25%, 50%, and 100% of nonexpansile SF6, 100% saline solution, and 100% room air. A sixth eye was injected with 0.35 cc of undiluted SF6 without vitrectomy. Guided by global positioning system, they were driven to the highest point of the highway connecting Mexico City with Puebla city and back, stopping every 300 m to assess intraocular pressure. The rabbit’s scleral rigidity and estimation for human eyes were done by using the Friedenwald nomogram. Maximum altitude was 3209 m (Δ949 m. There were significant differences in intraocular pressure on the rabbit eyes filled with SF6 at 100%, 50%, 25%, and 100% room air. Per every 100 m of altitude rise, the intraocular pressure increased by 1.53, 1.0046, 0.971, and 0.97 mmHg, respectively. Using the human Friedenwald rigidity coefficient, the human eye estimate for intraocular pressure change was 2.1, 1.8, 1.4, and 1.1 mmHg per every 100 m of attitude rise. Altitude changes have a significant impact on intraocular pressure. The final effect depends on the percentage of vitreous cavity fill and scleral rigidity.

  9. Physical exercise and glaucoma: a review on the roles of physical exercise on intraocular pressure control, ocular blood flow regulation, neuroprotection and glaucoma-related mental health.

    Science.gov (United States)

    Zhu, Ming Ming; Lai, Jimmy Shiu Ming; Choy, Bonnie Nga Kwan; Shum, Jennifer Wei Huen; Lo, Amy Cheuk Yin; Ng, Alex Lap Ki; Chan, Jonathan Cheuk Hung; So, Kwok Fai

    2018-01-16

    The benefits of physical exercise on health and well-being have been studied in a wide range of systemic and ocular diseases, including glaucoma, a progressive optic neuropathy characterized by accelerated apoptosis of retinal ganglion cells (RGCs). Elevated intraocular pressure (IOP) and insufficient ocular perfusion have been postulated to be the two main theories in glaucoma development and progression. The effects of exercise in these two aspects have been demonstrated by numerous researches. A review in 2009 focusing on these two theories concluded that exercise results in transient IOP reduction but an inconsistent elevation in ocular perfusion. However, the majority of the studies had been conducted in healthy subjects. Over the past decade, technological advancement has brought forth new and more detailed evidence regarding the effects of exercise. Moreover, the neuroprotective effect of exercise by upregulation of neurotrophin and enhancement of mitochondrial function has been a focus of interest. Apart from visual impairment, the mental health issues in patients with glaucoma, which include anxiety and depression, should also be addressed. In this review, we mainly focus on publications from the recent years, so as to provide a comprehensive review on the impact of physical exercise on IOP, ocular perfusion, neuroprotection and mental health in patients with glaucoma. © 2018 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  10. Comparison of the Tono-Pen and Goldmann tonometer for measuring intraocular pressure in patients with glaucoma.

    Science.gov (United States)

    Horowitz, Gregory S; Byles, Julie; Lee, John; D'Este, Catherine

    2004-12-01

    To estimate agreement between measurement of intraocular pressure (IOP) by the Tono-Pen and by the Goldmann tonometer. The hypothesis tested was that the mean difference in measurements would be or =25 mmHg), the mean difference between instruments (Tono-Pen reading minus Goldmann reading): was -4.2 mmHg (P = 0.0004), SD: 4.6, 95% limits of agreement: -13.2 to 4.8 mmHg and ICC = 0.76. Combining the analysis for both groups, the Tono-Pen significantly underestimated the IOP when the pressure was >20 mmHg. The Tono-Pen cannot replace the Goldmann tonometer in the sense that it will give the same readings of IOP. The accuracy of the Tono-Pen is increased, if at least two measurements are taken per eye and then averaged.

  11. Flashback behavior in a model swirl combustor at elevated pressure

    Science.gov (United States)

    Ranjan, Rakesh; Ebi, Dominik; Clemens, Noel

    2014-11-01

    Understanding of combustion physics at high pressure is essential for safe and efficient operation of gas turbine combustors. A new optically-accessible elevated pressure combustion facility has been developed for this purpose. The modular design of the chamber allows applying various optical diagnostic techniques and the installation of different types of combustors. In the current study, the effect of pressure on boundary layer flashback in lean-premixed swirl flames is investigated. Mixtures of hydrogen and methane at different equivalence ratios are tested. High-speed chemiluminescence imaging is employed to study the upstream flame propagation inside the mixing tube, which allows comparison to previous results of flashback at atmospheric pressure.

  12. Risk of Microgravity-Induced Visual Impairment and Elevated Intracranial Pressure (VIIP)

    Science.gov (United States)

    Otto, Christian

    2011-01-01

    Eight cases identified, represent 23.5% of the 34 crewmembers flown on the ISS, with inflight visual changes and pre-to-postflight refractive changes. In some cases, the changes were transient while in others they are persistent with varying degrees of visual impairment. (1) Decreased intraocular pressure (IOP) postflight was observed in 3 cases. (2) Fundoscopic exams revealed postflight findings of choroidal folds in 4 cases, optic disc edema in 5 cases and presence of cotton wool spots in 3 cases. (3) Optical coherence tomography (OCT) confirmed findings of choroidal folds and disc edema and documented retinal nerve fiber layer thickening (4 cases). (4) Findings from MRI examinations showed posterior globe flattening (5 cases) and optic nerve sheath distension (6 cases). (5) Opening cerebrospinal fluid (CSF) pressure was elevated in 4 cases postflight reflecting raised intracranial pressure. While the etiology remains unknown, hypotheses speculate that venous insufficiency or hypertension in the brain caused by cephalad fluid shifts during spaceflight are possible mechanisms for ocular changes in astronauts.

  13. Investigations of Sooting Laminar Coflow Diffusion Flames at Elevated Pressures

    KAUST Repository

    Steinmetz, Scott A.

    2016-12-01

    Soot is a common byproduct of hydrocarbon based combustion systems. It poses a risk to human and environmental health, and can negatively or positively affect combustor performance. As a result, there is significant interest in understanding soot formation in order to better control it. More recently, the need to study soot formation in engine relevant conditions has become apparent. One engine relevant parameter that has had little focus is the ambient pressure. This body of work focuses on the formation of soot in elevated pressure environments, and a number of investigations are carried out with this purpose. Laminar coflow diffusion flames are used as steady, simple soot producers. First, a commonly studied flame configuration is further characterized. Coflow flames are frequently used for fundamental flame studies, particularly at elevated pressures. However, they are more susceptible to buoyancy induced instabilities at elevated pressures. The velocity of the coflow is known to have an effect on flame stability and soot formation, though these have not been characterized at elevated pressures. A series of flames are investigated covering a range of flowrates, pressures, and nozzle diameters. The stability limits of coflow flames in this range is investigated. Additionally, an alternative strategy for scaling these flames to elevated pressures is proposed. Finally, the effect of coflow rate on soot formation is evaluated. Identification of fundamental flames for coordinated research can facilitate our understanding of soot formation. The next study of this work focuses on adding soot concentration and particle size information to an existing fundamental flame dataset for the purpose of numerical model validation. Soot volume fraction and average particle diameters are successfully measured in nitrogen-diluted ethylene-air laminar coflow flames at pressures of 4, 8, 12, and 16 atm. An increase in particle size with pressure is found up to 12 atm, where particle

  14. Patterns of care and persistence after incident elevated blood pressure.

    Science.gov (United States)

    Daley, Matthew F; Sinaiko, Alan R; Reifler, Liza M; Tavel, Heather M; Glanz, Jason M; Margolis, Karen L; Parker, Emily; Trower, Nicole K; Chandra, Malini; Sherwood, Nancy E; Adams, Kenneth; Kharbanda, Elyse O; Greenspan, Louise C; Lo, Joan C; O'Connor, Patrick J; Magid, David J

    2013-08-01

    Screening for hypertension in children occurs during routine care. When blood pressure (BP) is elevated in the hypertensive range, a repeat measurement within 1 to 2 weeks is recommended. The objective was to assess patterns of care after an incident elevated BP, including timing of repeat BP measurement and likelihood of persistently elevated BP. This retrospective study was conducted in 3 health care organizations. All children aged 3 through 17 years with an incident elevated BP at an outpatient visit during 2007 through 2010 were identified. Within this group, we assessed the proportion who had a repeat BP measured within 1 month of their incident elevated BP and the proportion who subsequently met the definition of hypertension. Multivariate analyses were used to identify factors associated with follow-up BP within 1 month of initial elevated BP. Among 72,625 children and adolescents in the population, 6108 (8.4%) had an incident elevated BP during the study period. Among 6108 with an incident elevated BP, 20.9% had a repeat BP measured within 1 month. In multivariate analyses, having a follow-up BP within 1 month was not significantly more likely among individuals with obesity or stage 2 systolic elevation. Among 6108 individuals with an incident elevated BP, 84 (1.4%) had a second and third consecutive elevated BP within 12 months. Whereas >8% of children and adolescents had an incident elevated BP, the great majority of BPs were not repeated within 1 month. However, relatively few individuals subsequently met the definition of hypertension.

  15. Correlation of intraocular pressure with blood pressure and body mass index in offsprings of diabetic patients: A cross-sectional study

    Directory of Open Access Journals (Sweden)

    Shailaja Patil, Anita Herur, Shashikala GV, Surekharani Chinagudi, Manjula R, Roopa Ankad, Sukanya Badami, Brid SV

    2014-07-01

    Full Text Available Background: Raised intraocular pressure (IOP has been associated with risk factors like hypertension, diabetes mellitus (DM, obesity, body mass index (BMI and sex, increasing the risk of glaucoma causing visual impairment and blindness. Since familial inheritance is known with glaucoma and DM, the aim was to study the IOP and its correlation with BMI and blood pressure (BP in offsprings of DM and also to predict the future/early onset of glaucoma in them. Methods: This was an observational study done in medical undergraduate students. 25 students were included in the study group (offsprings of diabetic parents-cases and 23 students in the control group (offsprings without diabetic history in parents. Height, weight, blood pressure and intraocular pressure were recorded in both the groups and these were compared. Statistical analysis was done by student’s t test and Pearson’s correlation. Results: Cases exhibited a lower IOP, BMI, mean arterial pressure (MAP and diastolic blood pressure (DBP, but not SBP, as compared to controls. These differences, however, were not statistically significant except DBP. There was a negative correlation found between IOP and BMI and also between IOP and MAP in cases, whereas in controls, there was a positive correlation found between BMI and IOP and no correlation between IOP and MAP. Conclusion: Offsprings of diabetic patients may be less prone for primary open angle glaucoma. Limitations: The limitations of the present study include a smaller sample size, study of the results in relation to paternal or maternal diabetic status and also of grandparents, so that the inheritance of diabetes and also of IOP can be studied.

  16. New insights into the genetics of primary open-angle glaucoma based on meta-analyses of intraocular pressure and optic disc characteristics.

    NARCIS (Netherlands)

    Springelkamp, H. (Henriët); Iglesias, A.I. (Adriana); Mishra, A. (Aniket); Höhn, R. (René); Wojciechowski, R. (Robert); Khawaja, A.P. (Anthony); Nag, A. (Abhishek); Wang, Y.X. (Ya Xing); Wang, J.J. (Jie Jin); Cuellar-Partida, G. (Gabriel); Gibson, J. (Jane); Cooke Bailey, J.N. (Jessica); Vithana, E.N. (Eranga); Gharahkhani, P. (Puya); Boutin, T. (Thibaud); Ramdas, W.D. (Wishal); Zeller, T. (Tanja); Luben, R.N. (Robert); Yonova-Doing, E. (Ekaterina); Viswanathan, A.C. (Ananth); Yazar, S. (Seyhan); Cree, A.J. (Angela); Haines, J.L. (Jonathan); Koh, J.Y. (Jia Yu); Souzeau, E. (Emmanuelle); Wilson, J.F. (James); Amin, N. (Najaf); Müller, C. (Christian); Venturini, C. (Cristina); Kearns, L.S. (Lisa); Hee Kang, J. (Jae); Consortium, N. (Neighborhood); Tham, Y.C. (Yih Chung); Zhou, T. (Tiger); van Leeuwen, E.M. (Elisabeth); Nickels, S. (Stefan); Sanfilippo, P. (Paul); Liao, J. (Jiemin); Linde, H.V. (Herma van der); Zhao, W. (Wanting); van Koolwijk, L.M. (Leonieke); Zheng, L. (Li); Rivadeneira, F. (Fernando); Baskaran, M. (Mani); van der Lee, S.J. (Sven); Perera, S. (Shamira); de Jong, P.T. (Paulus); Oostra, B.A. (Ben); Uitterlinden, A.G. (André); Fan, Q. (Qiao); Hofman, A. (Albert); Shyong Tai, E. (E-); Vingerling, J.R. (Johannes); Sim, X. (Xueling); Wolfs, R.C. (Roger); Teo, Y.Y. (Yik Ying); Lemij, H.G. (Hans); Khor, C.C. (Chiea Chuen); Willemsen, R. (Rob); Lackner, K.J. (Karl); Aung, T. (Tin); Jansonius, N.M. (Nomdo); Montgomery, G. (Grant); Wild, P.S. (Philipp); Young, T.L. (Terri); Burdon, K.P. (Kathryn); Hysi, P.G. (Pirro); Pasquale, L.R. (Louis); Wong, T.Y. (Tien Yin); Klaver, C.C. (Caroline); Hewitt, A.W. (Alex); Jonas, J.B. (Jost); Mitchell, P. (Paul); Lotery, A.J. (Andrew); Foster, P.J. (Paul); Vitart, V. (Veronique); Pfeiffer, N. (Norbert); Craig, J.E. (Jamie); Mackey, D.A. (David); Hammond, C.J. (Christopher); Wiggs, J.L. (Janey); Cheng, C.Y. (Ching-Yu); van Duijn, C.M. (Cornelia); MacGregor, S. (Stuart)

    2017-01-01

    textabstractPrimary open-angle glaucoma (POAG), the most common optic neuropathy, is a heritable disease. Siblings of POAG cases have a ten-fold increase risk of developing the disease. Intraocular pressure (IOP) and optic nerve head characteristics are used clinically to predict POAG risk. We

  17. New insights into the genetics of primary open-angle glaucoma based on meta-analyses of intraocular pressure and optic disc characteristics

    NARCIS (Netherlands)

    Springelkamp, Henriët; Iglesias, Adriana I; Mishra, Aniket; Höhn, René; Wojciechowski, Robert; Khawaja, Anthony P; Nag, Abhishek; Wang, Ya Xing; Wang, Jie Jin; Cuellar-Partida, Gabriel; Gibson, Jane; Cooke Bailey, Jessica N; Vithana, Eranga N; Gharahkhani, Puya; Boutin, Thibaud; Ramdas, Wishal D; Zeller, Tanja; Luben, Robert N; Yonova-Doing, Ekaterina; Viswanathan, Ananth C; Yazar, Seyhan; Cree, Angela J; Haines, Jonathan L; Koh, Jia Yu; Souzeau, Emmanuelle; Wilson, James F; Amin, Najaf; Müller, Christian; Venturini, Cristina; Kearns, Lisa S; Hee Kang, Jae; Consortium, Neighborhood; Tham, Yih Chung; Zhou, Tiger; van Leeuwen, Elisabeth M; Nickels, Stefan; Sanfilippo, Paul; Liao, Jiemin; Linde, Herma van der; Zhao, Wanting; van Koolwijk, Leonieke M E; Zheng, Li; Rivadeneira, Fernando; Baskaran, Mani; van der Lee, Sven J; Perera, Shamira; de Jong, Paulus T V M; Oostra, Ben A; Uitterlinden, André G; Fan, Qiao; Hofman, Albert; Shyong Tai, E-; Vingerling, Johannes R; Sim, Xueling; Wolfs, Roger C W; Teo, Yik Ying; Lemij, Hans G; Khor, Chiea Chuen; Willemsen, Rob; Lackner, Karl J; Aung, Tin; Jansonius, Nomdo M; Montgomery, Grant; Wild, Philipp S; Young, Terri L; Burdon, Kathryn P; Hysi, Pirro G; Pasquale, Louis R; Wong, Tien Yin; Klaver, Caroline C W; Hewitt, Alex W; Jonas, Jost B; Mitchell, Paul; Lotery, Andrew J; Foster, Paul J; Vitart, Veronique; Pfeiffer, Norbert; Craig, Jamie E; Mackey, David A; Hammond, Christopher J; Wiggs, Janey L; Cheng, Ching-Yu; van Duijn, Cornelia M; MacGregor, Stuart

    2017-01-01

    Primary open-angle glaucoma (POAG), the most common optic neuropathy, is a heritable disease. Siblings of POAG cases have a ten-fold increase risk of developing the disease. Intraocular pressure (IOP) and optic nerve head characteristics are used clinically to predict POAG risk. We conducted a

  18. New insights into the genetics of primary open-angle glaucoma based on meta-analyses of intraocular pressure and optic disc characteristics

    NARCIS (Netherlands)

    Springelkamp, Henriët; Iglesias, Adriana I.; Mishra, Aniket; Höhn, René; Wojciechowski, Robert; Khawaja, Anthony P.; Nag, Abhishek; Wang, Ya Xing; Wang, Jie Jin; Cuellar-Partida, Gabriel; Gibson, Jane; Cooke Bailey, Jessica N.; Vithana, Eranga N.; Gharahkhani, Puya; Boutin, Thibaud; Ramdas, Wishal D.; Zeller, Tanja; Luben, Robert N.; Yonova-Doing, Ekaterina; Viswanathan, Ananth C.; Yazar, Seyhan; Cree, Angela J.; Haines, Jonathan L.; Koh, Jia Yu; Souzeau, Emmanuelle; Wilson, James F.; Amin, Najaf; Müller, Christian; Venturini, Cristina; Kearns, Lisa S.; Kang, Jae Hee; Tham, Yih Chung; Zhou, Tiger; van Leeuwen, Elisabeth M.; Nickels, Stefan; Sanfilippo, Paul; Liao, Jiemin; van der Linde, Herma; Zhao, Wanting; van Koolwijk, Leonieke M.E.; Zheng, Li; Rivadeneira, Fernando; Baskaran, Mani; van der Lee, Sven J.; Perera, Shamira; de Jong, Paulus T.V.M.; Oostra, Ben A.; Uitterlinden, André G.; Fan, Qiao; Hofman, Albert; Tai, E. Shyong; Vingerling, Johannes R.; Sim, Xueling; C.W.Wolfs, Roger; Teo, Yik Ying; Lemij, Hans G.; Khor, Chiea Chuen; Willemsen, Rob; Lackner, Karl J.; Aung, Tin; Jansonius, Nomdo M.; Montgomery, Grant; Wild, Philipp S.; Young, Terri L.; Burdon, Kathryn P.; Hysi, Pirro G.; Pasquale, Louis R.; Wong, Tien Yin; Klaver, Caroline C.W.; Hewitt, Alex W.; Jonas, Jost B.; Mitchell, Paul; Lotery, Andrew J.; Foster, Paul J.; Vitart, Veronique; Pfeiffer, Norbert; Craig, Jamie E.; Mackey, David A.; Hammond, Christopher J.; Wiggs, Janey L.; Cheng, Ching Yu; van Duijn, Cornelia M.; MacGregor, Stuart

    2017-01-01

    Primary open-angle glaucoma (POAG), the most common optic neuropathy, is a heritable disease. Siblings of POAG cases have a ten-fold increased risk of developing the disease. Intraocular pressure (IOP) and optic nerve head characteristics are used clinically to predict POAG risk. We conducted a

  19. Clinical evaluation of the accuracy of intraocular pressure measurement by Tono-Pen XL in eyes with amniotic membrane patching.

    Science.gov (United States)

    Onguchi, Tatsuya; Takano, Yoji; Dogru, Murat; Tsubota, Kazuo; Shimazaki, Jun

    2005-03-01

    To evaluate the influence of amniotic membrane on intraocular pressure (IOP) measurement with the Tono-Pen. Observational case series. Eight patients with partial limbal dysfunction who underwent penetrating keratoplasty were recruited. Amniotic membranes were patched just after keratoplasty. One week postoperatively, amniotic membranes were removed, and accuracy of IOP measurement with the Tono-Pen was evaluated with comparisons before and after the removal. No epithelial defects were detected after the removal of amniotic membrane. Mean IOPs with and without amniotic membranes were 16.6 +/- 3.0 mm Hg (mean +/- SD) and 16.0 +/- 3.7 mm Hg, respectively. The difference was not statistically significant. Assessment of IOP with the Tono-Pen was observed to be accurate even when used over an amniotic membranes patch in cases who underwent penetrating keratoplasty.

  20. Influence on intraocular pressure of the postural change and daily activities in the early morning in suspected glaucoma patients

    Directory of Open Access Journals (Sweden)

    Ting Chen

    2014-05-01

    Full Text Available AIM:To evaluate the influence on intraocular pressure(IOPof the postural change and daily activities in the early morning in suspected glaucoma patients.METHODS:The supine and sitting IOP were measured and analyzed on 51 suspected glaucoma patients(100 eyeswith Icare rebound tonometer before and after getting up and daily activities in the early morning. RESULTS: The mean of sitting IOP of 51 patients was 17.12±4.53mmHg, which was significantly lower than the mean of supine IOP(19.14±5.51mmHg. The mean of IOP before and after daily activity of 51 patients were 17.12±4.53mmHg and 14.44±3.90mmHg respectively, which showed significantly difference. CONCLUSION:Postural change and daily activities can result in significant changes of IOP in suspected glaucoma patients.

  1. Investigation of postoperative intraocular pressure in cases of silicone oil removal using 25-gauge transconjunctival sutureless vitrectomy with oblique incisions.

    Science.gov (United States)

    Takashina, Hirotsugu; Watanabe, Akira; Tsuneoka, Hiroshi

    2015-01-01

    The purpose of this study was to investigate postoperative intraocular pressure (IOP) in cases of silicone oil (SO) removal when using 25-gauge transconjunctival sutureless vitrectomy (TSV) with oblique incisions. We enrolled ten consecutive eyes with SO removal (SO group) and eleven consecutive eyes with idiopathic epiretinal membrane (ERM) as the initial vitrectomy (ERM group) in cases using 25-gauge TSV with oblique incisions. Postoperative IOPs were compared between the two groups at each of the four examination periods. No significant differences were identified in any of the periods examined. The use of 25-gauge TSV with oblique incisions resulted in almost equivalent postoperative IOPs between cases with SO removal and idiopathic ERM as the initial operation. Self-sealing sclerotomy in 25-gauge TSV with oblique incisions may primarily involve the valve architecture, and be complemented by vitreous incarceration.

  2. Applanation optical coherence elastography: noncontact measurement of intraocular pressure, corneal biomechanical properties, and corneal geometry with a single instrument

    Science.gov (United States)

    Singh, Manmohan; Han, Zhaolong; Nair, Achuth; Schill, Alexander; Twa, Michael D.; Larin, Kirill V.

    2017-02-01

    Current clinical tools provide critical information about ocular health such as intraocular pressure (IOP). However, they lack the ability to quantify tissue material properties, which are potent markers for ocular tissue health and integrity. We describe a single instrument to measure the eye-globe IOP, quantify corneal biomechanical properties, and measure corneal geometry with a technique termed applanation optical coherence elastography (Appl-OCE). An ultrafast OCT system enabled visualization of corneal dynamics during noncontact applanation tonometry and direct measurement of micro air-pulse induced elastic wave propagation. Our preliminary results show that the proposed Appl-OCE system can be used to quantify IOP, corneal biomechanical properties, and corneal geometry, which builds a solid foundation for a unique device that can provide a more complete picture of ocular health.

  3. Selective A2A receptor antagonist prevents microglia-mediated neuroinflammation and protects retinal ganglion cells from high intraocular pressure-induced transient ischemic injury.

    Science.gov (United States)

    Madeira, Maria H; Boia, Raquel; Elvas, Filipe; Martins, Tiago; Cunha, Rodrigo A; Ambrósio, António Francisco; Santiago, Ana Raquel

    2016-03-01

    Glaucoma is a leading cause of vision loss and blindness worldwide, characterized by chronic and progressive neuronal loss. Reactive microglial cells have been recognized as a neuropathologic feature, contributing to local inflammation and retinal neurodegeneration. In a recent in vitro work (organotypic cultures), we demonstrated that blockade of adenosine A2A receptor (A2AR) prevents the neuroinflammatory response and affords protection to retinal ganglion cells (RGCs) against exposure to elevated hydrostatic pressure (EHP), to mimic elevated intraocular pressure (IOP), the main risk factor for glaucoma development. Herein, we investigated whether a selective A2AR antagonist (SCH 58261) could modulate retinal microglia reactivity and their inflammatory response. Furthermore, we took advantage of the high IOP-induced transient ischemia (ischemia-reperfusion, I-R) animal model to evaluate the protective role of A2AR blockade in the control of retinal neuroinflammation and neurodegeneration. Primary microglial cell cultures were challenged either with lipopolysaccharide or with EHP, in the presence or absence of A2AR antagonist SCH 58261 (50 nM). In addition, I-R injury was induced in adult Wistar rats after intravitreal administration of SCH 58261 (100 nM, 5 μL). Our results showed that SCH 58261 attenuated microglia reactivity and the increased expression and release of proinflammatory cytokines. Moreover, intravitreal administration of SCH 58261 prevented I-R-induced cell death and RGC loss, by controlling microglial-mediated neuroinflammatory response. These results prompt the proposal that A2AR blockade may have great potential in the management of retinal neurodegenerative diseases characterized by microglia reactivity and RGC death, such as glaucoma and ischemic diseases. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Comparison of Obesity, Overweight and Elevated Blood Pressure in ...

    African Journals Online (AJOL)

    [19] Hypertension and pre-hypertension were defined as elevated SBP or DBP ≥ 95th percentile and SBP or DBP between the 90th and < 95th percentile for the age, sex and height respectively according to the recommendation of National Blood Pressure Education. Program.[19]. Children with obesity and overweight as ...

  5. The hidden magnitude of raised blood pressure and elevated blood ...

    African Journals Online (AJOL)

    user

    The hidden magnitude of raised blood pressure and elevated blood glucose in Ethiopia: A call for initiating community based NCDs risk factors screening program. Abebe Bekele1, Terefe Gelibo1, Kassahun Amenu1, Theodros Getachew1, Atkure Defar1, Habtamu Teklie1,. Tefera Taddele1, Girum Taye1, Misrak Getnet1, ...

  6. The hidden magnitude of raised blood pressure and elevated blood ...

    African Journals Online (AJOL)

    user

    and only very small percentage of people had been aware of their high blood pressure and elevated blood sugar. Policy makers in the health sector including other health development partners need to strengthen health system and design nation-wide population based strategy to establish community based screening ...

  7. Effects of selective beta 1- and beta 2-adrenoreceptor agonists and antagonists on intraocular pressure in the cat.

    Science.gov (United States)

    Colasanti, B K; Trotter, R R

    1981-01-01

    Ocular tension of cats was measured after topical administration of the selective beta 1-adrenergic agonist CGP 7760B, the selective beta 1-adrenergic antagonist atenolol, the selective beta 2-adrenergic agonist salbutamol, the selective beta 2-adrenergic antagonist H 35/25, and the mixed beta 1- and beta 2-adrenergic antagonist timolol. Although atenolol did not alter intraocular pressure, CGP 7760B produced a modest decrease amounting to 3 to 4 mm Hg. Salbutamol, H 35/25, and timolol each produced a dose-dependent lowering of ocular tension, with maximal reductions amounting to 7, 5, and 5 mm Hg, respectively. Sympathetically denervated cat eyes showed supersensitivity to the pressure-lowering effect of salbutamol. In contrast, sympathectomy markedly reduced the effects of H 35/25 and timolol on ocular tension. Eyes rendered subsensitive to the pressure-lowering effects of cholinomimetics by chronic echothiophate treatment likewise showed diminished responsiveness to H 35/25 and timolol. Pretreatment with timolol (3 hr) completely abolished the pressure-lowering effect of salbutamol, and pretreatment with atenolol likewise completely antagonized the effect of CGP 7760B. These results suggest that beta-adrenergic receptors in the anterior segment of the cat eye are predominantly beta 2. Although beta-adrenergic antagonists apparently exert their effects on ocular tension by action at beta-adrenergic receptors, a cholinergic mechanism may be involved as well.

  8. Measurement of rock properties at elevated pressures and temperatures

    International Nuclear Information System (INIS)

    Pincus, H.J.; Hoskins, E.R.

    1985-01-01

    The papers in this volume were presented at an ASTM symposium held on 20 June 1983 in conjunction with the 24th Annual Rock Mechanics Symposium at Texas A and M University, College Station, TX. The purpose of these papers is to present recent developments in the measurement of rock properties at elevated pressures and temperatures, and to examine and interpret the data produced by such measurement. The need for measuring rock properties at elevated pressures and temperatures has become increasingly important in recent years. Location and design of nuclear waste repositories, development of geothermal energy sites, and design and construction of deep excavations for civil, military, and mining engineering require significantly improved capabilities for measuring rock properties under conditions substantially different from those prevailing in most laboratory and in situ work. The development of high-pressure, high-temperature capabilities is also significant for the analysis of tectonic processes

  9. Evaluation of the effect of daily activities on intraocular pressure in healthy people: is the 20 mmHg border safe?

    Science.gov (United States)

    Baser, Gonen; Karahan, Eyyup; Bilgin, Sinan; Unsal, Ugur

    2017-08-07

    The aim of this prospective study was to evaluate the intraocular pressure (IOP) variations during daily activities such as reading, speaking and carrying in regard to investigating whether an elevation or decrease exists. Forty-four eyes of 44 healthy subjects were evaluated. The IOP was measured in relaxation and after reading, speaking and carrying a shopping bag for 5 min on different days, respectively. The subjects rested for 15 min between the activities. Mean initial IOP levels were compared with mean IOP levels after reading, speaking and carrying a shopping bag with paired t test. A p value of 0.05 was considered as statistically significant. We observed no changes in mean IOP after reading (p = 0.188). Mean IOP was increased after speaking and carrying compared with mean basic IOP (p = 0.001 and p = 0.001, very significant, respectively). The mean IOP began to decrease 15 min after speaking and carrying and came back to the baseline values one hour later. The IOP is not stable during daily activities. Simple actions such as carrying or speaking have an increasing effect on IOP. This should be taken into consideration in glaucoma patients during control measurements, especially in patients in whom the IOP was near to the 20 mmHg border.

  10. Investigating Soot Morphology in Counterflow Flames at Elevated Pressures

    KAUST Repository

    Amin, Hafiz Muhammad Fahid

    2018-01-01

    Practical combustion devices such as gas turbines and diesel engines operate at high pressures to increase their efficiency. Pressure significantly increases the overall soot yield. Morphology of these ultra-fine particles determines their airborne lifetime and their interaction with the human respiratory system. Therefore, investigating soot morphology at high pressure is of practical relevance. In this work, a novel experimental setup has been designed and built to study the soot morphology at elevated pressures. The experimental setup consists of a pressure vessel, which can provide optical access from 10° to 165° for multi-angle light scattering, and a counterflow burner which produces laminar flames at elevated pressures. In the first part of the study, N2-diluted ethylene/air and ethane air counterflow flames are stabilized from 2 to 5 atm. Two-angle light scattering and extinction technique have been used to study the effects of pressure on soot parameters. Path averaged soot volume fraction is found to be very sensitive to pressure and increased significantly from 2 to 5 atm. Primary particle size and aggregate size also increased with pressure. Multi-angle light scattering is also performed and flames are investigated from 3 to 5 atm. Scattering to absorption ratio is calculated from multi-angle light scattering and extinction data. Scattering to absorption ratio increased with pressure whereas the number of primary particles in an aggregate decreased with increasing pressure. In the next part of the study, Thermophoretic Sampling of soot is performed, in counterflow flames from 3 to 10 atm, followed by transmission electron microscopy. Mean primary particle size increased with pressure and these trends are consistent withour light scattering measurements. Fractal properties of soot aggregates are found to be insensitive to pressure. 2D diffused light line of sight attenuation (LOSA) and Laser Induced Incandescence (LII) are used to measure local soot

  11. Espessura central da córnea e a medida da pressão intra-ocular com diferentes tonômetros Could the central cornea thickness change the intraocular pressure results obtained by different tonometers

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    Priscila Yumi Kitice

    2007-12-01

    Full Text Available OBJETIVO: Analisar a possível variação da pressão intra-ocular, obtida por diferentes tonômetros, com a espessura central da córnea. MÉTODOS: Após a medida da pressão intra-ocular com o ICare, instilou-se uma gota de colírio anestésico e fez-se a medida da espessura da córnea e, também, a medida da pressão intra-ocular com o tonômetro de contorno dinâmico de Pascal. Em seguida, instilou-se uma gota de colírio de fluoresceína e mediu-se a pressão intra-ocular o tonômetro de aplanação de Goldmann. RESULTADOS: 138 olhos de 71 pacientes foram examinados e divididos em 3 grupos de acordo com a espessura central da córnea. A análise da pressão intra-ocular mostrou valores concordantes quando se utilizou o ICare e o tonômetro de contorno dinâmico de Pascal, com média de diferença de -0,2. A pressão intra-ocular medida com o tonômetro de contorno dinâmico de Pascal apresentou valores maiores que os obtidos com o tonômetro de aplanação de Goldmann, com média de diferença de -3,1. Uma diferença estatisticamente significante foi obtida nas medidas com o ICare e tonômetro de aplanação de Goldmann. CONCLUSÃO: Existe uma diferença estatisticamente significante entre os valores da PIO obtidos com ICare, tonômetro de contorno dinâmico de Pascal e tonômetro de aplanação de Goldmann, quando relacionados com a espessura central da córnea.PURPOSE: Could the central corneal thickness (CCT change the intraocular pressure (IOP measured by ICARE (IC GOLDMANN APPLANATION TONOMETER (GAT and PASCAL DYNAMIC COUNTOUR TONOMETER (PDCT. METHODS: Before using the anesthesia we have measured the IOP with IC tonometer. After that we have used topical anesthesia to obtain the CCT using an ultrasound pachymeter (Mentor Co. and the IOP measured by PCDT followed by a drop of fluorescein to measured IOP with GAT. RESULTS: 138 eyes of 71 patients were analyzed. Patients were divided into 3 groups according to CCT. Best correlation was

  12. Extension of the Heat Flux Method to Elevated Pressures

    Energy Technology Data Exchange (ETDEWEB)

    Slikker, W.J.

    2008-12-15

    Laminar premixed flames are used in many residential and industrial applications such as surface and Bunsen burners in boilers and central heating systems. A key parameter for a premixed flame is the laminar burning velocity because practically it determines the rate with which a combustible mixture is consumed and fundamentally it contains the basic information regarding the diffusivity and reactivity of the flame. Also, the laminar burning velocity can be used to estimate the turbulent burning velocity and therefore it is an important parameter in designing combustion systems that work under high temperatures and pressures. Much research has been done to determine the laminar burning velocities of premixed hydrocarbon-air flames at both atmospheric and elevated pressures. For atmospheric pressure the reported burning velocities from various measurement methods agree very well, but for high pressures the results show a lot of scattering. The methods used for measuring the burning velocity at higher pressures need stretch corrections and therefore it is interesting to use a method that does not need to be corrected for stretch and to compare the results. The heat flux method makes use of a flat flame and therefore needs no stretch corrections. This method has successfully been used at (sub) atmospheric pressure and in this work it is extended to elevated pressure for the first time. An experimental setup for pressures up to 3 bar was used for measurements of premixed methane-air flames with equivalence ratios ranging from 0.8 to 1.4 for both 2 and 3 bar. The measured burning velocities are higher than most reported data and numerical calculations based on kinetic mechanisms, but very good agreement with the most recent (2007) experimental data is obtained. With use of experimental data from low pressure experiments obtained with the same setup, a correlation between burning velocity and pressure for stoichiometric methane-air flames is found for pressures ranging

  13. Effect of ophthalmic administration of S-596 (Arotinolol) on intraocular pressure and haemodynamics in health volunteers: comparison with timolol.

    Science.gov (United States)

    Nakashima, M; Uematsu, T; Takiguchi, Y; Hashimoto, H; Watanabe, I; Morioka, S; Hibino, T

    1985-01-01

    The effects on intraocular pressure (IOP) and haemodynamics of two beta-blockers, arotinolol and timolol, administered topically to the eye, were studied in 6 healthy volunteers in a cross-over trial. 0.5% timolol or 0.5% arotinolol ophthalmic solutions drop was instilled in both eyes of the volunteers at an interval of 48 hours. Timolol lowered IOP by about 31.9% 1 hour after administration and the effect continued until 3 h, whilst arotinolol lowered it significantly 2 h after instillation and the same maximum effect as that of timolol was obtained after 3 h. Arotinolol was detected in blood in all subject and timolol in blood in one subject, although it was found in all subjects in urine. Both drugs lowered heart rate at rest and attenuated the increase in the double product (products of blood pressure and heart rate) at exercise. The effect of timolol on the double products was larger. Thus, arotinolol and timolol decreased IOP to similar extent, although the maximal effect of arotinolol was delayed. Arotinolol as well as timolol affected haemodynamics through absorption into circulation, but the former had less effect on haemodynamics during exercise.

  14. Influence of head flexion on intraocular pressure, cardiovascular, and respiratory responses in patients undergoing cataract surgery after endotracheal intubation

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    MR Safavi

    2007-11-01

    Full Text Available Background: In cataract surgery, the periorbital area is prepared anddraped after induction of general anesthesia and endotracheal intubation (ETI.For this purpose, the patient’s head and neck is usually flexed 30 to 45degrees. Neck flexion causes displacement of the endotracheal tube tip towardthe carina. Stimulation of the tracheal mucosa may cause bucking, increasedintraocular pressure (IOP, laryngospasm and/or bronchospasm, during lightanesthesia. Laryngeal constriction and all components of the tracheal responsemay affect end-tidal carbon dioxide pressure (PETCO2 and peripheral arterialhemoglobin oxygen saturation (SpaO2. Thus, in the current study, weinvestigated the influence of head and neck flexion on heart rate (HR, systolicand diastolic blood pressure (SAP and DAP, SpaO2, PETCO2, and IOP in patientsundergoing cataract surgery with endotracheal intubation during generalanesthesia.Patients and Methods: The present prospective study comprised patientsaged from 40 to 80 year with 106 American Society of Anesthesia (ASA physicalstatus I and II. Anesthesia was induced with thiopental sodium, lidocaine andfentanyl. Atracurium 0.5 mg/kg was administered to facilitate trachealintubation. HR, SAP, DAP, SpaO2, PETCO2, and IOP were measured at 1, 2, and 5minutes after head flexion.Results: Mean SAP, DAP, IOP, and HR was increased after ETI and headflexion compared with baseline values. PETCO2 and SpaO2 were decreased after ETIand at 1, 2 minutes after head flexion compared with baseline values.Conclusion: In patients undergoing cataract surgery during generalanesthesia, endotracheal tube movement caused changes in head and neck positionresulting in significant effects on heart rate, systolic and diastolic bloodpressures, laryngeal reflexes, SpaO2, PETCO2, and intraocular pressure.

  15. Pattern of intraocular pressure reduction following laser trabeculoplasty in open-angle glaucoma patients: comparison between selective and nonselective treatment

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    Almeida Jr ED

    2011-07-01

    Full Text Available Eglailson Dantas Almeida Júnior1, Luciano Moreira Pinto1,2, Rodrigo Antonio Brant Fernandes1,2, Tiago Santos Prata1,31Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil; 2Cerpo Oftalmologia, São Paulo, Brazil; 3Hospital Medicina dos Olhos, São Paulo, BrazilObjective: To compare the pattern of intraocular pressure (IOP reduction following selective laser trabeculoplasty (SLT versus argon laser trabeculoplasty (ALT in open-angle glaucoma (OAG patients, and to investigate the ability of initial IOP reduction to predict mid-term success.Methods: A prospective, nonrandomized, interventional case series was carried out. Consecutive uncontrolled OAG glaucoma patients underwent SLT or ALT; the same preoperative medical regimen was maintained during follow-up. Data collected included age, type of OAG, pre- and postoperative IOP, number of glaucoma medications, and surgical complications. Post-treatment assessments were scheduled at day 1 and 7 and months 1, 3, and 6.Results: A total of 45 patients (45 eyes were enrolled [SLT group (n = 25; ALT group (n = 20]. Groups were similar for age, baseline IOP, and number of glaucoma medications (P ≥ 0.12. We found no significant differences in mean IOP reduction between SLT (5.1 ± 2.5 mmHg; 26.6% and ALT (4.4 ± 2.8 mmHg; 22.8% groups at month 6 (P = 0.38. Success rates (IOP ≤ 16 mmHg and IOP reduction ≥25% at last follow-up visit were similar for SLT (72% and ALT (65% groups (P = 0.36. Comparing the pattern of IOP reduction (% of IOP reduction at each visit between groups, we found a greater effect following SLT compared with ALT at day 7 (23.7% ± 13.7% vs 8.1% ± 9.5%; P < 0.001. No significant differences were observed at other time points (P ≥ 0.32. Additionally, the percentage of IOP reduction at day 7 and at month 6 were significantly correlated in the SLT group (R2 = 0.36; P < 0.01, but not in the ALT group (P = 0.89. Early postoperative success predicted late

  16. Heritabilities of intraocular pressure in the population of Korea: the Korean National Health and Nutrition Examination Survey 2008-2009.

    Science.gov (United States)

    Kim, Na Rae; Park, Hyun Ju; Suh, Young Ju; Chin, Hee Seung; Kim, Chan Yun

    2014-03-01

    Intraocular pressure (IOP) is the principal modifiable risk factor for the progression of primary open-angle glaucoma. Studies that have measured the IOP directly in large numbers of matched parent-offspring pairs are limited in Asian populations. To compare IOPs in parents and their offspring in Korea. Family-based cohort study examining data from the Korean National Health and Nutrition Examination Survey conducted between 2008 and 2009. Data were obtained from 9700 participants from Korea. Familial correlations for IOP were calculated in different types of relative pairs. Variance component methods were used to obtain heritability estimates. The individuals were stratified into 2 groups (those with and those without an IOP of ≥ 19 mm Hg; ie, high IOP group and nonhigh IOP group) based on the mean plus 2 SD IOP value of the entire study population. We evaluated the impact of parents' high IOP on offspring's high IOP. The relationship between parental systemic disease and high IOP in their offspring was also investigated. The mean (SD) IOPs in the right and left eyes were 13.90 (2.74) and 13.89 (2.74) mm Hg, respectively. Correlation coefficient estimates between parent-offspring pairs, sibling pairs, and spouse pairs for IOP were significant as 0.19, 0.31, and 0.29 (P < .001, P = .001, and P < .001, respectively). The total variance of the phenotype under study was explained by 2 sources of variation, additive genetic (36% [95% CI, 32%-40%]) and unique environment (64% [95% CI, 60%-68%]). The risks of high IOP conferred by parents' high IOP were found to be significant for participants whose parents had high IOP (odds ratio, 9.76 [95% CI, 2.16-44.12]). In this study, high IOP was not associated with parental diabetes mellitus, hypertension, obesity, or metabolic syndrome. Intraocular pressure showed a significant heritable tendency from parents to their offspring with a heritability estimate of 0.36 in Asian populations. The risk of high IOP was

  17. Bimatoprost ophthalmic solution 0.03% lowered intraocular pressure of normal-tension glaucoma with minimal adverse events

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    Tsumura T

    2012-09-01

    Full Text Available Toyoaki Tsumura,1 Keiji Yoshikawa,2 Hirotaka Suzumura,3 Tairo Kimura,4 Satoshi Sasaki,5 Itaru Kimura,6 Ryuji Takeda71Department of Ophthalmology, Fussa Hospital, Fussa, Tokyo, Japan; 2Yoshikawa Eye Clinic, Machida, Tokyo, Japan; 3Department of Ophthalmology, Nakano General Hospital, Nakano, Tokyo, Japan; 4Ueno Eye Clinic, Ueno, Tokyo, Japan; 5Sasaki Eye Clinic, Ueno, Tokyo, Japan; 6Department of Ophthalmology, Juntendo University Urayasu Hospital, Urayasu, Chiba, Japan; 7Department of Biological Chemistry, Faculty of Agriculture, Kinki University, Nara, Nara, JapanPurpose: The aim of this study was to evaluate the efficacy and safety of bimatoprost ophthalmic solution 0.03% (bimatoprost in Japanese normal-tension glaucoma (NTG patients with an intraocular pressure (IOP of 18 mmHg or less.Methods: Bimatoprost was instilled into the unilateral conjunctival sac of Japanese NTG patients with a baseline IOP of 18 mmHg or less. The time courses of IOP, conjunctival hyperemia, superficial punctate keratitis, and adverse events were examined at 2, 4, 8, and 12 weeks post bimatoprost instillation.Results: Thirty-two of the 38 enrolled NTG patients (mean age, 64.1 ± 12.6 years; 19 males and 19 females completed the study, with six patients unable to complete the study (two patients discontinued because of side effects and four patients withdrew. The levels of IOP in the treated eyes were significantly reduced (P < 0.0001 from the baseline IOP levels. No significant change in IOP was observed in the fellow eyes. There were significant increases in conjunctival hyperemia. No significant superficial punctate keratitis scores were noted between the baseline and each point examined. Eyelash disorder, eyelid pigmentation, and deepening of the upper eyelid sulcus were observed in 28, six, and three eyes, respectively.Conclusion: Bimatoprost effectively lowered the IOP. It was well tolerated in Japanese NTG patients, with few patients having to discontinue

  18. 21 CFR 886.4270 - Intraocular gas.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Intraocular gas. 886.4270 Section 886.4270 Food... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4270 Intraocular gas. (a) Identification. An intraocular gas is a device consisting of a gaseous fluid intended to be introduced into the eye to place pressure...

  19. To evaluate the effects of dexmedetomidine on intraocular pressure and haemodynamic changes in response to laryngoscopy and tracheal intubation

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    Tanuja

    2014-01-01

    Full Text Available Background: The most important prerequisites for neurosurgeries are brain relaxation, need of stable haemodynamics with less fluctuation in intracranial pressure and speedy recovery from anaesthesia. Endotracheal intubation is the major stressful stimuli that can elicit a marked pressor response. Various drugs have been used to attenuate these reflexes. Dexmedetomidine, a highly selective alpha 2-adrenoceptor agonist, have neuroprotective, cardioprotective, and sedative effects so it is potentially useful during neuroanaesthesia. This is a prospective randomised control trial carried out to see whether administration of Dexmedetomidine prior to intubation can attenuate the various haemodynamic responses, intraocular pressure (IOP and the requirement of induction dose of propofol in control and study group. Materials and Methods: Fifty patients (ASA grade 1, 2 scheduled for intracranial tumour surgeries were divided into two groups (25 each. Group D received Dexmedetomidine 0.8 μg/kg i.v. over 10 mins and group C received 20 ml saline. Anaesthesia induced with Propofol, dose adjusted using bispectral index monitor. The groups were compared with IOP, Heart rate (HR, Mean arterial pressure (MAP, and dose of Propofol required for induction. Results : Groups were well matched for their demographic data and pre-operative. IOP in both the eyes decreases significantly after premedication and remained below baseline even after 10 th min of intubation in group D while in Group C; it increased significantly after intubation and remained above baseline. The difference between groups was also statistically significant. HR and MAP decreased significantly in patients of group D compared to group C (P < 0.05. Patients were more haemodynamicaly stable at all time points after premedication in group D (P < 0.05. Propofol requirements for induction was lesser in group D (P < 0.05. Bradycardia and hypotension incidences were higher in group D. Conclusion

  20. Exercise training prevents increased intraocular pressure and sympathetic vascular modulation in an experimental model of metabolic syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Castro, E.F.S. [Unidade de Hipertensão, Instituto do Coração, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP (Brazil); Mostarda, C.T. [Universidade Federal do Maranhão, São Luís, MA (Brazil); Rodrigues, B. [Laboratório do Movimento Humano, Universidade São Judas Tadeu, São Paulo, SP (Brazil); Moraes-Silva, I.C. [Unidade de Hipertensão, Instituto do Coração, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP (Brazil); Feriani, D.J. [Laboratório do Movimento Humano, Universidade São Judas Tadeu, São Paulo, SP (Brazil); De Angelis, K. [Laboratório de Fisiologia Translacional, Universidade Nove de Julho, São Paulo, SP (Brazil); Irigoyen, M.C. [Unidade de Hipertensão, Instituto do Coração, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP (Brazil)

    2015-02-13

    The present study aimed to study the effects of exercise training (ET) performed by rats on a 10-week high-fructose diet on metabolic, hemodynamic, and autonomic changes, as well as intraocular pressure (IOP). Male Wistar rats receiving fructose overload in drinking water (100 g/L) were concomitantly trained on a treadmill for 10 weeks (FT group) or kept sedentary (F group), and a control group (C) was kept in normal laboratory conditions. The metabolic evaluation comprised the Lee index, glycemia, and insulin tolerance test (KITT). Arterial pressure (AP) was measured directly, and systolic AP variability was performed to determine peripheral autonomic modulation. ET attenuated impaired metabolic parameters, AP, IOP, and ocular perfusion pressure (OPP) induced by fructose overload (FT vs F). The increase in peripheral sympathetic modulation in F rats, demonstrated by systolic AP variance and low frequency (LF) band (F: 37±2, 6.6±0.3 vs C: 26±3, 3.6±0.5 mmHg{sup 2}), was prevented by ET (FT: 29±3, 3.4±0.7 mmHg{sup 2}). Positive correlations were found between the LF band and right IOP (r=0.57, P=0.01) and left IOP (r=0.64, P=0.003). Negative correlations were noted between KITT values and right IOP (r=-0.55, P=0.01) and left IOP (r=-0.62, P=0.005). ET in rats effectively prevented metabolic abnormalities and AP and IOP increases promoted by a high-fructose diet. In addition, ocular benefits triggered by exercise training were associated with peripheral autonomic improvement.

  1. Exercise training prevents increased intraocular pressure and sympathetic vascular modulation in an experimental model of metabolic syndrome

    International Nuclear Information System (INIS)

    Castro, E.F.S.; Mostarda, C.T.; Rodrigues, B.; Moraes-Silva, I.C.; Feriani, D.J.; De Angelis, K.; Irigoyen, M.C.

    2015-01-01

    The present study aimed to study the effects of exercise training (ET) performed by rats on a 10-week high-fructose diet on metabolic, hemodynamic, and autonomic changes, as well as intraocular pressure (IOP). Male Wistar rats receiving fructose overload in drinking water (100 g/L) were concomitantly trained on a treadmill for 10 weeks (FT group) or kept sedentary (F group), and a control group (C) was kept in normal laboratory conditions. The metabolic evaluation comprised the Lee index, glycemia, and insulin tolerance test (KITT). Arterial pressure (AP) was measured directly, and systolic AP variability was performed to determine peripheral autonomic modulation. ET attenuated impaired metabolic parameters, AP, IOP, and ocular perfusion pressure (OPP) induced by fructose overload (FT vs F). The increase in peripheral sympathetic modulation in F rats, demonstrated by systolic AP variance and low frequency (LF) band (F: 37±2, 6.6±0.3 vs C: 26±3, 3.6±0.5 mmHg 2 ), was prevented by ET (FT: 29±3, 3.4±0.7 mmHg 2 ). Positive correlations were found between the LF band and right IOP (r=0.57, P=0.01) and left IOP (r=0.64, P=0.003). Negative correlations were noted between KITT values and right IOP (r=-0.55, P=0.01) and left IOP (r=-0.62, P=0.005). ET in rats effectively prevented metabolic abnormalities and AP and IOP increases promoted by a high-fructose diet. In addition, ocular benefits triggered by exercise training were associated with peripheral autonomic improvement

  2. Effect of benzalkonium chloride?free travoprost on intraocular pressure and ocular surface symptoms in patients with glaucoma previously on latanoprost: an open-label study

    OpenAIRE

    Lopes, Joao F.; Hubatsch, Douglas A.; Amaris, Patricia

    2015-01-01

    Background Prostaglandin analogs reduce intraocular pressure (IOP) in patients with open-angle glaucoma or ocular hypertension; however, these medications may affect the ocular surface and elicit ocular discomfort when preserved with benzalkonium chloride (BAK). Methods This was an open-label, single-arm study conducted in Latin America from February 2012 to May 2013. Patients with open-angle glaucoma or ocular hypertension who were intolerant of latanoprost 0.005?% were transitioned to recei...

  3. Effect of altered eating habits and periods during Ramadan fasting on intraocular pressure, tear secretion, corneal and anterior chamber parameters.

    Science.gov (United States)

    Kerimoglu, H; Ozturk, B; Gunduz, K; Bozkurt, B; Kamis, U; Okka, M

    2010-01-01

    To determine whether altered eating habits and periods, especially the pre-dawn meal, during Ramadan fasting have any significant effect on intraocular pressure (IOP), tear secretion, corneal and anterior chamber parameters. IOP, basal tear secretion (BTS), reflex tear secretion (RTS), and Pentacam measurements of 31 healthy volunteers were performed at 0800 and 1600 hours during Ramadan fasting and 1 month later during non-fasting period. Comparison of measurements between fasting and non-fasting periods at 0800 hours revealed significantly higher values for IOP (P=0.005), RTS (P=0.006), and BTS (P=0.014) during fasting. Conversely at 1600 hours, IOP was significantly lower during fasting (P=0.013) and no statistically significant difference was noted for RTS and BTS. IOP showed a diurnal variation of 2.45 mmHg (P<0.001) and BTS showed a 3.06 mm decrease (P=0.04) during the fasting period. No significant differences could be found in the corneal and anterior chamber parameters during fasting and non-fasting periods. Our results revealed that fluid loading at the pre-dawn meal during Ramadan fasting might increase the IOP and tear secretion in the early morning period and these values decrease remarkably at the end of 12 h of fasting due to dehydration.

  4. Comparison of Tono-Pen and Goldmann applanation tonometers for measurement of intraocular pressure in healthy children.

    Science.gov (United States)

    Bradfield, Yasmin S; Kaminski, Brett M; Repka, Michael X; Melia, Michele; Davitt, Bradley V; Johnson, David A; Kraker, Raymond T; Manny, Ruth E; Matta, Noelle S; Schloff, Susan; Weise, Katherine K

    2012-06-01

    To assess the agreement of intraocular pressure (IOP) measured with the Tono-Pen and the Goldmann applanation tonometer (GAT) in normal children and adolescents. A total of 439 subjects from birth to 11 mm Hg in the office setting. Using the average of GAT and Tono-Pen IOPs to estimate the true IOP, the average difference (GAT - Tono-Pen) was 0.4 mm Hg at IOP of 10 mm Hg and -3.0 mm Hg at IOP of 20 mm Hg. The 95% limits of agreement on the average difference between instruments were ± 6.4 mm Hg in the office setting and ± 6.8 mm Hg under general anesthesia. Larger differences between instruments were found with younger age. Standard error of measurement with the Tono-Pen was 1.44 mm Hg and 1.82 mm Hg for the office and anesthesia settings, respectively. Thicker corneas were associated with higher IOP with both the GAT and the Tono-Pen. In normal children, average differences between IOP measured by Tono-Pen and GAT were small, although there was substantial test-retest variability. Younger age was associated with larger average differences, as was higher IOP in the office setting. Copyright © 2012 American Association for Pediatric Ophthalmology and Strabismus. Published by Mosby, Inc. All rights reserved.

  5. Intraoperative measurement of intraocular pressure in vitrectomized aphakic air-filled eyes using the Tono-Pen XL.

    Science.gov (United States)

    Badrinath, S S; Vasudevan, R; Murugesan, R; Basti, S; Nicholson, A D; Singh, P; Gopal, L; Sharma, T; Rao, S B; Abraham, C

    1993-01-01

    The Tono-Pen XL (Bio-Rad, Santa Ana, CA) was compared with manometer readings for intraoperative measurement of intraocular pressure (IOP) in 40 eyes of 40 consecutive patients after vitrectomy, lensectomy, and fluid-air exchange. Tono-Pen readings corresponding to manometer readings of 10, 20, 30, 40, and 50 mmHg were obtained in a masked fashion with a randomized sequence of manometer readings. A correlation was obtained between the manometer and Tono-Pen readings (r = 0.96 in emmetropic eyes and r = 0.93 in myopic eyes). The regression curve that represents the calibration curve of Tono-Pen in terms of the manometer readings for air-filled vitrectomized eyes was obtained. Any Tono-Pen reading can be easily translated into the corresponding manometer reading by referring to the curve. The Tono-Pen can therefore be effectively used to accurately determine intraoperative IOP in eyes undergoing vitrectomy, lensectomy, and fluid-air exchange.

  6. Effect of corneal thickness on intraocular pressure measurements with the pneumotonometer, Goldmann applanation tonometer, and Tono-Pen.

    Science.gov (United States)

    Bhan, Archana; Browning, Andrew C; Shah, Sunil; Hamilton, Robin; Dave, Dinesh; Dua, Harminder S

    2002-05-01

    To compare intraocular pressure (IOP) measurements of the Ocular Blood Flow (OBF) pneumotonometer, Goldmann applanation tonometer, and Tono-Pen in eyes with normal corneas of various thicknesses. IOP was measured with an OBF pneumotonometer, Tono-Pen and Goldmann applanation tonometer in random order in 181 eyes with normal corneas. Central corneal thickness (CCT) was measured using an ultrasonic pachymeter after all IOP determinations had been made. Right and left eyes were analyzed separately for statistical purposes. With all instruments, IOP varied with CCT, even though the variation in IOP was large. Readings with the OBF pneumotonometer showed a mean increase in IOP with increasing CCT of 0.28 mm Hg/10 microm, an increase of 0.23 mm Hg/10 microm with the Goldmann tonometer, and of 0.10 mm Hg/10 microm with the Tono-Pen. The OBF pneumotonometer consistently recorded comparatively higher IOPs than the other two instruments. The Tono-Pen is least affected by CCT when used to measure IOP in eyes with normal corneas. The OBF pneumotonometer appears to be more affected by variation in CCT than the Goldmann tonometer. This is contrary to expectations, based on the mechanism of measurement of IOP of the OBF pneumotonometer.

  7. Influence of keratometric readings on comparative intraocular pressure measurements with Goldmann, Tono-Pen, and noncontact tonometers.

    Science.gov (United States)

    Paranhos, A; Paranhos, F R; Prata, J A; Omi, C A; Mello, P A; Shields, M B

    2000-06-01

    To evaluate the influence of keratometric measurements on the concordance of intraocular pressure (IOP) readings with three applanation tonometers. The IOPs of 404 eyes of 202 patients from a general eye clinic were measured by Goldmann, Tono-Pen XL, and noncontact Nidek NT 2000 tonometers. Differences in the IOP measurements between Goldmann and the other two tonometers (deltaIOPG-TP and deltaIOPG-NCT) were analyzed in the overall group and within three subgroups based on keratometry measures: flatter, intermediate, and steeper corneas (quartiles as cut-off points). Regression analysis of deltaIOP and keratometry measures was also performed. Right and left eyes were analyzed separately. The IOP readings taken with the Goldmann tonometer were significantly higher than those taken with either of the other two tonometers within the overall study population. The deltaIOP within the three keratometric subgroups was not statistically significant except for deltaIOPG-TP in the right eyes. Regression analysis showed that keratometry and deltaIOPG-TP and deltaIOPG-NCT had a significant but very weak coefficient of correlation in the right eye, but not in the left. Corneal curvature within the normal range does not have a clinically significant influence on the concordance of IOP readings obtained with Goldmann and Tono-Pen or noncontact tonometers.

  8. Comparisons of intraocular pressure measurements: Goldmann applanation tonometry, noncontact tonometry, Tono-Pen tonometry, and dynamic contour tonometry.

    Science.gov (United States)

    Hsu, S-Y; Sheu, M-M; Hsu, A-H; Wu, K-Y; Yeh, J-I; Tien, J-N; Tsai, R-K

    2009-07-01

    To compare intraocular pressure (IOP) readings between Tono-Pen tonometry and GAT, between noncontact tonometry (NCT) and GAT, and between dynamic contour tonometry (DCT) and Goldmann applanation tonometry (GAT). The correlation between IOP reading and possible confounder was identified. This observational cross-sectional study enrolled sixty-two healthy subjects. All IOP and ocular pulse amplitude (OPA) measurements were taken by a single ophthalmologist; mean keratometric power (MK), central corneal thickness (CCT), and lens thickness (LT) were measured by a single experienced technician. Stepwise multiple regression analysis indicated that GAT (P=0.017) and DCT (P=0.002) readings correlated positively with MK; GAT, NCT, and Tono-Pen readings correlated positively with CCT (P<0.05); NCT (P=0.035), and DCT (P=0.016) readings correlated negatively with LT; GAT (P=0.006) and Tono-Pen (P=0.009) readings correlated positively with OPA. The K, CCT, LT, and OPA are confounders in tonometry readings.

  9. Measurement of treatment compliance using a medical device for glaucoma patients associated with intraocular pressure control: a survey

    Science.gov (United States)

    Nordmann, Jean-Philippe; Baudouin, Christophe; Renard, Jean-Paul; Denis, Philippe; Lafuma, Antoine; Laurendeau, Caroline; Jeanbat, Viviane; Berdeaux, Gilles

    2010-01-01

    Objective: To identify and characterize treatment compliance profiles of glaucoma patients and evaluate the association with intraocular pressure (IOP). Methods: A computerized device (Travalert®) that recorded daily instillation times and eye-drop counts was given for 3 months. Patients were declared compliant when at least 2 drops were instilled per day. Compliance rates were calculated for weekdays and weekends, separately, over 8 consecutive weeks. A principal components analysis (PCA) was followed by an ascendant hierarchical classification (AHC) to identify compliance groups. Results: 140 patients were recruited (mean age 65.5 years; 51.8% female) of whom 83.6% had primary open-angle glaucoma with mean IOP 23.9 mmHg before Travalert® use. 60.7% were treated with DuoTrav® (travoprost timolol fixed combination) and 39.3% with travoprost. The PCA identified two axes (compliance and treatment weeks). The AHC identified 3 compliance groups: ‘high’ (56.6%, approx. 80% compliance), ‘medium’ (21.2%, approx. 50% compliance), and ‘low’ (22.1%, approx. 20% compliance). Demographics and glaucoma parameters did not predict low compliance. Final mean IOP was 16.1 mmHg, but higher in the low compliance group (17.7 mmHg, P = 0.02). Conclusions: Compliance measurement by a medical device showed compliance rates <80% by 50% (approx.) of patients, significantly impacting IOP control. No demographic or glaucoma variable was associated with low compliance. PMID:20689790

  10. Modification of hydrophobic acrylic intraocular lens with poly(ethylene glycol) by atmospheric pressure glow discharge: A facile approach

    International Nuclear Information System (INIS)

    Lin Lin; Wang Yao; Huang Xiaodan; Xu Zhikang; Yao Ke

    2010-01-01

    To improve the anterior surface biocompatibility of hydrophobic acrylic intraocular lens (IOL) in a convenient and continuous way, poly(ethylene glycol)s (PEGs) were immobilized by atmospheric pressure glow discharge (APGD) treatment using argon as the discharge gas. The hydrophilicity and chemical changes on the IOL surface were characterized by static water contact angle and X-ray photoelectron spectroscopy to confirm the covalent binding of PEG. The morphology of the IOL surface was observed under field emission scanning electron microscopy and atomic force microscopy. The surface biocompatibility was evaluated by adhesion experiments with platelets, macrophages, and lens epithelial cells (LECs) in vitro. The results revealed that the anterior surface of the PEG-grafted IOL displayed significantly and permanently improved hydrophilicity. Cell repellency was observed, especially in the PEG-modified IOL group, which resisted the attachment of platelets, macrophages and LECs. Moreover, the spread and growth of cells were suppressed, which may be attributed to the steric stabilization force and chain mobility effect of the modified PEG. All of these results indicated that hydrophobic acrylic IOLs can be hydrophilic modified by PEG through APGD treatment in a convenient and continuous manner which will provide advantages for further industrial applications.

  11. Twenty-four hour intraocular pressure monitoring with the SENSIMED Triggerfish contact lens: effect of body posture during sleep.

    Science.gov (United States)

    Beltran-Agulló, Laura; Buys, Yvonne M; Jahan, Farzana; Shapiro, Colin M; Flanagan, John G; Cheng, Jason; Trope, Graham E

    2017-10-01

    To determine the difference in relative intraocular pressure (IOP) measured by the SENSIMED Triggerfish (TF) contact lens in flat compared with 30° head-up sleeping positions in patients with progressive primary open-angle glaucoma or normotensive glaucoma, based on recent or recurrent disc haemorrhage. Prospective, randomised, cross-over, open-label comparative study. IOP was monitored for 24 hours using TF on two separate sessions. Patients were randomly assigned to sleep flat one night and 30° head-up the other. Outputs in arbitrary units were obtained. Sleep and wake periods were defined as 22:00-6:00 and 8:00-22:00, respectively. Mean TF values during sleep and wake periods and wake-sleep and sleep-wake slopes were calculated for each session. TF output signals were compared between positions. Twelve subjects completed the study. Significant mean positive slopes were noted during the sleep period for both positions (pSleep position affects IOP as measured by TF in some patients with progressive glaucoma. The upward drift in TF output detected in >50% of the subjects requires further investigation to establish whether the increased output values over time are an artefact induced by the TF or a real change in IOP. NCT01351779. 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/.

  12. Comparison of postoperative intraocular pressure changes between 23-gauge transconjunctival sutureless vitrectomy and conventional 20-gauge vitrectomy

    Science.gov (United States)

    Ahn, S J; Woo, S J; Ahn, J; Park, K H

    2012-01-01

    Purpose To compare the intraocular pressure (IOP) after 23-gauge transconjunctival sutureless vitrectomy (TSV) and conventional 20-gauge vitrectomy for various vitreoretinal diseases. Methods This was a retrospective interventional case series including 338 cases of 23-gauge TSV and 476 cases of 20-gauge vitrectomy with minimum follow-up period of 1 month. Postoperative 1 day, 1 week and 1 month IOPs were compared. Multiple regression analysis to assess the actual effect of gauge of vitrectomy on postoperative IOP was performed including intraoperative and postoperative factors influencing postoperative IOP as covariates. Results The mean IOP of 20-gauge vitrectomy was significantly higher than that of 23-gauge TSV (20.6±8.02 mm Hg vs12.8±4.48 mm Hg, Pgauge TSV demonstrated more stable course than that of 20-gauge vitrectomy. At 1 day post vitrectomy, the incidence of hypertony was higher in 20-gauge, whereas that of hypotony was higher in 23-gauge. Among risk factors, the 20-gauge vitrectomy showed the strongest association with postoperative 1 day IOP rise. Conclusion Twenty-three-gauge TSV has stable and lower IOP in the early postoperative period than the 20-gauge vitrectomy. In patients whose retina and optic nerves are vulnerable to higher or fluctuating IOP, 23-gauge TSV may be more beneficial. PMID:22388595

  13. Association of biometric factors with anterior chamber angle widening and intraocular pressure reduction after uneventful phacoemulsification for cataract.

    Science.gov (United States)

    Huang, Guofu; Gonzalez, Eduardo; Lee, Roland; Chen, Yi-Chun; He, Mingguang; Lin, Shan C

    2012-01-01

    To evaluate anterior chamber biometric factors associated with the degree of angle widening and intraocular pressure (IOP) reduction after phacoemulsification. University of California, San Francisco, California, USA. Case series. Anterior chamber parameters obtained by anterior segment coherence tomography were compared preoperatively and 3 months postoperatively. Measurements included the angle opening distance 500 μm anterior to the scleral spur (AOD500), trabecular-iris space area 500 μm from the scleral spur (TISA500), iris curvature (I-Curv), anterior chamber angle (ACA), trabecular-iris space area, anterior chamber volume, anterior chamber width, and lens vault (LV). The study enrolled 73 eyes. The mean patient age was 77.45 years ± 7.84 (SD); 65.75% of patients were women. From preoperatively to 3 months postoperatively, the mean AOD500 increased significantly (0.254 ± 0.105 to 0.433 ± 0.108 mm) and the mean IOP decreased significantly (14.97 ± 3.35 to 12.62 ± 3.37 mm Hg) (Pbiometric factors. Preoperative LV appears to be a significant factor in angle widening and IOP reduction after phacoemulsification. Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  14. Study of intraocular pressure after 23-gauge and 25-gauge pars plana vitrectomy randomized to fluid versus air fill.

    Science.gov (United States)

    Ho, Lawrence Y; Garretson, Bruce R; Ranchod, Tushar M; Balasubramaniam, Mamtha; Ruby, Alan J; Capone, Antonio; Drenser, Kimberly A; Williams, George A; Hassan, Tarek S

    2011-06-01

    To determine if a difference in intraocular pressure (IOP) exists after small-gauge pars plana vitrectomy randomized to fluid versus 80% sterile air fill. Ninety-two eyes undergoing 23-gauge and 25-gauge transconjunctival pars plana vitrectomy were randomized to fluid versus air fill, and IOP was measured at 5 different time points. There is no difference in the mean IOP for eyes undergoing small-gauge pars plana vitrectomy randomized to fluid versus air fill after vitrectomy. Using 23-gauge instrumentation, the mean immediate and 2-hour postoperative IOPs were statistically lower than the mean preoperative IOP. The mean Postoperative Day 1 and Week 1 IOPs were statistically higher than the mean immediate postoperative IOP. Using 25-gauge instrumentation, the mean IOP was not statistically different at any time points in the 2 groups. When comparing 23-gauge with 25-gauge instrumentation, the immediate postoperative IOP was statistically lower and the rate of suture closure for sclerotomies was higher for 23-gauge vitrectomy. When performing 23-gauge or 25-gauge pars plana vitrectomy, there was no difference in mean IOP for fluid- versus air-filled eyes. However, the mean IOP in the immediate postoperative period was statistically lower, and there was a higher rate of suture closure for 23-gauge compared with 25-gauge instrumentation.

  15. Influence of sutureless 23-gauge sclerotomy architecture on postoperative intraocular pressure decrease: results of a multivariate analysis.

    Science.gov (United States)

    Tahiri Joutei Hassani, Rachid; El Sanharawi, Mohamed; Adam, Raphael; Monin, Claire; Dupont-Monod, Sylvère; Baudouin, Christophe

    2013-05-01

    To evaluate the factors affecting the postoperative intraocular pressure (IOP) decrease in 23-gauge (23-G) sutureless vitrectomy, including incision architecture evaluated by anterior segment spectral-domain optical coherence tomography (SD-OCT). A prospective cohort study of 43 patients who underwent primary transconjunctival 23-G pars plana vitrectomy. All sclerotomy wounds were imaged 1 day after surgery using the anterior segment module of SD-OCT (OCT Spectralis, Heidelberg Engineering, Heidelberg, Germany). 23-G sclerotomy architecture, preoperative and postoperative medical data were also prospectively collected. Multivariate logistic regression analysis, with backward elimination, found that surgery duration (adjusted OR = 9.17, p = 0.020) and loss of wound apposition (adjusted OR = 15.12, p = 0.022) were risk factors for significant postoperative IOP decrease (≥3 mmHg) 1 day after surgery; while age, gender, myopia, and gas tamponade were not risk or protective factors for postoperative IOP decrease. In 23-G pars plana vitrectomy, the early postoperative decrease in IOP is mainly influenced by surgery duration and the self-sealing nature of the sclerotomy. The IOP decrease was not influenced by the presence or the absence of gas tamponade.

  16. Comparison of postoperative intraocular pressure changes between 23-gauge transconjunctival sutureless vitrectomy and conventional 20-gauge vitrectomy.

    Science.gov (United States)

    Ahn, S J; Woo, S J; Ahn, J; Park, K H

    2012-06-01

    To compare the intraocular pressure (IOP) after 23-gauge transconjunctival sutureless vitrectomy (TSV) and conventional 20-gauge vitrectomy for various vitreoretinal diseases. This was a retrospective interventional case series including 338 cases of 23-gauge TSV and 476 cases of 20-gauge vitrectomy with minimum follow-up period of 1 month. Postoperative 1 day, 1 week and 1 month IOPs were compared. Multiple regression analysis to assess the actual effect of gauge of vitrectomy on postoperative IOP was performed including intraoperative and postoperative factors influencing postoperative IOP as covariates. The mean IOP of 20-gauge vitrectomy was significantly higher than that of 23-gauge TSV (20.6 ± 8.02 mm Hg vs 12.8 ± 4.48 mm Hg, Pgauge TSV demonstrated more stable course than that of 20-gauge vitrectomy. At 1 day post vitrectomy, the incidence of hypertony was higher in 20-gauge, whereas that of hypotony was higher in 23-gauge. Among risk factors, the 20-gauge vitrectomy showed the strongest association with postoperative 1 day IOP rise. Twenty-three-gauge TSV has stable and lower IOP in the early postoperative period than the 20-gauge vitrectomy. In patients whose retina and optic nerves are vulnerable to higher or fluctuating IOP, 23-gauge TSV may be more beneficial.

  17. Dynamic changes in optic disc morphology, choroidal thickness, anterior chamber parameters, and intraocular pressure during Valsalva maneuver

    Directory of Open Access Journals (Sweden)

    Alper Mete

    Full Text Available ABSTRACT Purpose: To investigate the effects of the Valsalva maneuver (VM on optic disc morphology, choroidal thickness, and anterior chamber parameters. Methods: This prospective observational study included 60 eyes of 60 healthy subjects. The anterior chamber parameters, including central corneal thickness (CCT, anterior chamber depth (ACD, anterior chamber angle (ACA, anterior chamber volume (ACV, pupil diameter (PD, axial length (AL, subfoveal and peripapillary choroidal thickness, optic disc parameters, and intraocular pressure (IOP, were measured at rest and during VM. Results: VM did not have any significant influence on AL, subfoveal and peripapillary choroidal thickness, optic disc area, rim area, cup area, cup-to-disc area ratio, vertical cup-to-disc ratio, rim volume, cup volume, and nerve head volume measurements (for all; p >0.05. IOP and PD significantly increased during VM (for both; p <0.001. VM significantly decreased CCT, ACD, ACA, and ACV values (for all; p <0.001. Moreover, the optic nerve cup volume decreased and the horizontal cup-to-disc ratio significantly increased during VM (for both; p <0.05. Conclusions: VM may cause transient changes in IOP, optic disc morphology, and anterior chamber parameters.

  18. Bimatoprost ophthalmic solution 0.03% lowered intraocular pressure of normal-tension glaucoma with minimal adverse events.

    Science.gov (United States)

    Tsumura, Toyoaki; Yoshikawa, Keiji; Suzumura, Hirotaka; Kimura, Tairo; Sasaki, Satoshi; Kimura, Itaru; Takeda, Ryuji

    2012-01-01

    The aim of this study was to evaluate the efficacy and safety of bimatoprost ophthalmic solution 0.03% (bimatoprost) in Japanese normal-tension glaucoma (NTG) patients with an intraocular pressure (IOP) of 18 mmHg or less. Bimatoprost was instilled into the unilateral conjunctival sac of Japanese NTG patients with a baseline IOP of 18 mmHg or less. The time courses of IOP, conjunctival hyperemia, superficial punctate keratitis, and adverse events were examined at 2, 4, 8, and 12 weeks post bimatoprost instillation. Thirty-two of the 38 enrolled NTG patients (mean age, 64.1 ± 12.6 years; 19 males and 19 females) completed the study, with six patients unable to complete the study (two patients discontinued because of side effects and four patients withdrew). The levels of IOP in the treated eyes were significantly reduced (P superficial punctate keratitis scores were noted between the baseline and each point examined. Eyelash disorder, eyelid pigmentation, and deepening of the upper eyelid sulcus were observed in 28, six, and three eyes, respectively. Bimatoprost effectively lowered the IOP. It was well tolerated in Japanese NTG patients, with few patients having to discontinue because of adverse events.

  19. Travoprost with sofZia® preservative system lowered intraocular pressure of Japanese normal tension glaucoma with minimal side effects.

    Science.gov (United States)

    Mizoue, Shiro; Nakano, Tadashi; Fuse, Nobuo; Iwase, Aiko; Matsumoto, Shun; Yoshikawa, Keiji

    2014-01-01

    This study aimed to evaluate the effect of travoprost with sofZia® preservative system for lowering the intraocular pressure (IOP) of Japanese normal tension glaucoma (NTG) patients. In this prospective, multicenter, open-label study, Japanese NTG patients with baseline IOPs superficial punctate keratopathy, and adverse events were examined at week 4, 8, and 12 after drug instillation. One-hundred and three of the 107 enrolled patients (baseline IOP =15.2±2.0 mmHg [mean ± standard deviation]) completed the study. The mean IOP value as well as percent reduction was significantly reduced at each visit after travoprost with sofZia® initiation (Psuperficial punctate keratopathy. The cumulative incidence of side effects such as eyelash changes, eyelid pigmentation, and deepening of the upper lid was 47.6%, 27.2%, and 16.5%, respectively. Travoprost preserved with sofZia® effectively lowered the IOP of Japanese NTG patients. It was well tolerated with few discontinuations due to adverse events.

  20. Comparison of intraocular pressure measurements with the digital tonometer TGDc-01 'PRA' and the Goldmann applanation tonometer.

    Science.gov (United States)

    Meyer, Michael W; Gockeln, Roland; Hoy, Ludwig; Meyer, Andrea; Erb, Carl

    2004-01-01

    To compare intraocular pressure (IOP) measurements obtained with the digital tonometer TGDc-01 'PRA' with those from a Goldmann applanation tonometer (GAT). The IOP in 176 eyes of 88 healthy volunteers was measured prospectively in a sitting position. One single measurement, generated by the TGDc-01 PRA, was compared with a single reading from the GAT. Mean IOP values were 13.0 +/- 3.7 mm Hg for the TGDc-01 PRA (range, 4-22 mm Hg) and 14.9 +/- 3.2 mm Hg for the GAT (range, 8-27 mm Hg). The mean difference was 1.9 mm Hg with a standard deviation of 2.77 mm Hg, and this was statistically significant (p PRA underestimated IOP on an average of 1.9 mm Hg. Only 50.6% of all measurements were within the +/-2 mm Hg difference range. Thus, the TGDc-01 PRA has no high coincidence degree with the GAT. Both methods were not equivalent. Copyright (c) 2004 S Karger AG, Basel.

  1. Determination of reference values for intraocular pressure and Schirmer tear test results in clinically normal domestic donkeys (Equus asinus).

    Science.gov (United States)

    Selk Ghaffari, Masoud; Sabzevari, Amin; Ghamsari, SeyedMehdi; Shad, Hussein

    2017-11-25

    This study was conducted to establish normal reference range for the Schirmer tear test (STT) and intraocular pressure (IOP) in clinically normal donkeys for use in clinical practice. Sixteen adult Ethiopian domestic donkeys were used in this study. Complete ophthalmic examinations were performed without chemical restraint. STT values were evaluated in both eyes of all donkeys using a commercial STT strip. IOP was measured in both eyes with a Tono-Pen Vet (Reichert. USA) without using regional nerve blocks. STT values for all eyes (n=32) were 22.1±6.9 mm/minute with a range of 13-35 mm/minute. Comparison of mean STT values between right (n=16) and left eyes (n=16) showed no differences (P=0.6). Mean ±sd IOP values by applanation tonometry were 17.8±3.7 mmHg (range 13.5-24.5 mmHg). Comparison of mean IOP values between right (n=16) and left eyes (n=16) showed no differences (P=0.7). This initial survey provides means and ranges for IOP and STT values in donkeys. These data will assist veterinary ophthalmologists in more accurate diagnosis and management of ophthalmic diseases in donkeys, including keratoconjunctivitis sicca and glaucoma. © British Veterinary Association (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  2. Goldmann applanation tonometry compared with corneal-compensated intraocular pressure in the evaluation of primary open-angle Glaucoma

    Directory of Open Access Journals (Sweden)

    Ehrlich Joshua R

    2012-09-01

    Full Text Available Abstract Background To better understand the role of corneal properties and intraocular pressure (IOP in the evaluation of primary open-angle glaucoma (POAG; and to determine the feasibility of identifying glaucomatous optic neuropathy (GON using IOP corrected and uncorrected for corneal biomechanics. Methods Records from 1,875 eyes of consecutively evaluated new patients were reviewed. Eyes were excluded if central corneal thickness (CCT or Ocular Response Analyzer (ORA measurements were unavailable. Presence or absence of GON was determined based on morphology of the optic disc, rim and retinal nerve fiber layer at the time of clinical examination, fundus photography and Heidelberg Retinal Tomography. Goldmann-applanation tonometry (GAT in the untreated state was recorded and Goldmann-correlated (IOPg and corneal-compensated IOP (IOPcc were obtained using the ORA. Glaucomatous eyes were classified as normal or high-tension (NTG, HTG using the conventional cutoff of 21 mm Hg. One eligible eye was randomly selected from each patient for inclusion. Results A total of 357 normal, 155 HTG and 102 NTG eyes were included. Among NTG eyes, IOPcc was greater than GAT (19.8 and 14.4 mm Hg; p  Conclusions IOPcc may account for measurement error induced by corneal biomechanics. Compared to GAT, IOPcc may be a superior test in the evaluation of glaucoma but is unlikely to represent an effective diagnostic test.

  3. Effect on Intraocular Pressure of Switching from Latanoprost and Travoprost Monotherapy to Timolol Fixed Combinations in Patients with Normal-Tension Glaucoma

    Directory of Open Access Journals (Sweden)

    Ryoko Igarashi

    2014-01-01

    Full Text Available Purpose. To evaluate the effect on intraocular pressure (IOP of switching from latanoprost and travoprost monotherapy to timolol fixed combinations in Japanese patients with normal-tension glaucoma (NTG. Methods. 27 NTG patients (54 eyes were compared IOP, superficial punctuate keratitis (SPK scores, and conjunctival injection scores in eyes treated with prostaglandin (PG or PG analog/beta-blocker (PG/b fixed-combination 6 months after the change in therapy. Results. The mean baseline intraocular pressure was 17.4±1.59 mmHg in eyes receiving PG therapy only and 17.4±1.69 mmHg in eyes switched to PG/b. Switching to fixed combination therapy from PG monotherapy, the mean IOP was 13.1±1.79 mmHg (P<0.001  (-24.71% reduction from baseline at 6 months. The mean conjunctival injection score was 0.69 for eyes on PG monotherapy and 0.56 for eyes on fixed combination therapy (P=0.028. The mean SPK scores were 0.46 and 0.53. This difference was not statistically significant (P=0.463. Conclusions. Switching from PG monotherapy to PG/b fixed combination therapy for NTG resulted in a greater intraocular pressure reduction than PG alone without increasing the number of instillations.

  4. Effect on intraocular pressure of switching from latanoprost and travoprost monotherapy to timolol fixed combinations in patients with normal-tension glaucoma.

    Science.gov (United States)

    Igarashi, Ryoko; Togano, Tetsuya; Sakaue, Yuta; Yoshino, Takaiko; Ueda, Jun; Fukuchi, Takeo

    2014-01-01

    Purpose. To evaluate the effect on intraocular pressure (IOP) of switching from latanoprost and travoprost monotherapy to timolol fixed combinations in Japanese patients with normal-tension glaucoma (NTG). Methods. 27 NTG patients (54 eyes) were compared IOP, superficial punctuate keratitis (SPK) scores, and conjunctival injection scores in eyes treated with prostaglandin (PG) or PG analog/beta-blocker (PG/b) fixed-combination 6 months after the change in therapy. Results. The mean baseline intraocular pressure was 17.4 ± 1.59 mmHg in eyes receiving PG therapy only and 17.4 ± 1.69 mmHg in eyes switched to PG/b. Switching to fixed combination therapy from PG monotherapy, the mean IOP was 13.1 ± 1.79 mmHg (P < 0.001)  (-24.71% reduction from baseline) at 6 months. The mean conjunctival injection score was 0.69 for eyes on PG monotherapy and 0.56 for eyes on fixed combination therapy (P = 0.028). The mean SPK scores were 0.46 and 0.53. This difference was not statistically significant (P = 0.463). Conclusions. Switching from PG monotherapy to PG/b fixed combination therapy for NTG resulted in a greater intraocular pressure reduction than PG alone without increasing the number of instillations.

  5. Elevated cerebrospinal fluid pressure in patients with Alzheimer's disease

    Directory of Open Access Journals (Sweden)

    Fellmann Jere

    2006-05-01

    Full Text Available Abstract Background Abnormalities in cerebrospinal fluid (CSF production and turnover, seen in normal pressure hydrocephalus (NPH and in Alzheimer's disease (AD, may be an important cause of amyloid retention in the brain and may relate the two diseases. There is a high incidence of AD pathology in patients being shunted for NPH, the AD-NPH syndrome. We now report elevated CSF pressure (CSFP, consistent with very early hydrocephalus, in a subset of AD patients enrolled in a clinical trial of chronic low-flow CSF drainage. Our objective was to determine the frequency of elevated CSFP in subjects meeting National Institutes of Neurological and Communicative Diseases and Stroke – Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA criteria for AD, excluding those with signs of concomitant NPH. Methods AD subjects by NINCDS-ADRDA criteria (n = 222, were screened by history, neurological examination, and radiographic imaging to exclude those with clinical or radiographic signs of NPH. As part of this exclusion process, opening CSFP was measured supine under general anesthesia during device implantation surgery at a controlled pCO2 of 40 Torr (40 mmHg. Results Of the 222 AD subjects 181 had pressure measurements recorded. Seven subjects (3.9% enrolled in the study had CSFP of 220 mmH20 or greater, mean 249 ± 20 mmH20 which was significantly higher than 103 ± 47 mmH2O for the AD-only group. AD-NPH patients were significantly younger and significantly less demented on the Mattis Dementia Rating Scale (MDRS. Conclusion Of the AD subjects who were carefully screened to exclude those with clinical NPH, 4% had elevated CSFP. These subjects were presumed to have the AD-NPH syndrome and were withdrawn from the remainder of the study.

  6. Effects of the topically applied calcium-channel blocker flunarizine on intraocular pressure in clinically normal dogs.

    Science.gov (United States)

    Greller, Andrew L; Hoffman, Allison R; Liu, Chengcheng; Ying, Gui-shuang; Vudathala, Daljit K; Acland, Gregory M; Komáromy, András M

    2008-02-01

    To determine effects of the topically applied calcium-channel blocker flunarizine on intraocular pressure (IOP) in clinically normal dogs. 20 dogs. Baseline diurnal IOPs were determined by use of a rebound tonometer on 2 consecutive days. Subsequently, 1 randomly chosen eye of each dog was treated topically twice daily for 5 days with 0.5% flunarizine. During this treatment period, diurnal IOPs were measured. In addition, pupillary diameter and mean arterial blood pressure (MAP) were evaluated. Serum flunarizine concentrations were measured on treatment day 5. Intraday fluctuation of IOP was analyzed by use of an ANOVA for repeated measures and a trend test. Changes in IOP from baseline values were assessed and compared with IOPs for the days of treatment. Values were also compared between treated and untreated eyes. A significant intraday fluctuation in baseline IOP was detected, which was highest in the morning (mean +/- SE, 15.8 +/- 0.63 mm Hg) and lowest at night (12.9 +/- 0.61 mm Hg). After 2 days of treatment, there was a significant decrease in IOP from baseline values in treated (0.93 +/- 0.35 mm Hg) and untreated (0.95 +/- 0.34 mm Hg) eyes. There was no significant treatment effect on pupillary diameter or MAP. Flunarizine was detected in serum samples of all dogs (mean +/- SD, 3.89 +/- 6.36 microg/L). Topically applied flunarizine decreased IOP in dogs after 2 days of twice-daily application. This calcium-channel blocker could be effective in the treatment of dogs with glaucoma.

  7. Effects of hemodialysis on corneal and anterior chamber morphometry and intraocular pressure in patients with end-stage renal disease

    Directory of Open Access Journals (Sweden)

    Mehtap Caglayan

    Full Text Available ABSTRACT Purpose: To evaluate the effects of hemodialysis (HD on corneal and anterior chamber morphometry, as well as intraocular pressure (IOP in patients with end-stage renal disease. Methods: Fifty right eyes were examined 30 minutes before and after HD. IOP was measured with a Goldmann applanation tonometer, and Ehlers' formula was used to calculate the corrected IOP values. The central corneal thickness (CCT, corneal volume (CV, keratometric values, anterior chamber depth (ACD, aqueous depth (AQD, anterior chamber volume (ACV, and anterior chamber angle (ACA in the nasal and temporal quadrants were measured with a Sirius anterior segment analysis system. Blood urea nitrogen levels, body mass, and systolic and diastolic arterial pressure were also measured before and after HD. Results: The mean age was 60.80 ± 13.38 (range: 35-80 years. The mean uncorrected and corrected IOP values decreased from 18.06 ± 3.91 and 18.31 ± 4.83 mmHg to 16.94 ± 3.87 and 16.95 ± 4.74 mmHg after HD, respectively (p=0.011 and p=0.003, respectively. The mean CCT decreased from 536.38 ± 24.73 to 533.18 ± 27.25 µm (p=0.002, and the mean CV decreased from 57.52 ± 3.15 to 55.68 ± 3.55 mm³ (p0.05 for all values. There were no significant correlations between the ocular and systemic parameters (p>0.05 for all correlations. Conclusions: Uncorrected IOP, corrected IOP, CCT, and CV values decreased after HD, whereas the anterior chamber morphometry values remained similar between the measurements performed before and after HD.

  8. Autotaxin-Lysophosphatidic Acid Pathway in Intraocular Pressure Regulation and Glaucoma Subtypes.

    Science.gov (United States)

    Honjo, Megumi; Igarashi, Nozomi; Kurano, Makoto; Yatomi, Yutaka; Igarashi, Koji; Kano, Kuniyuki; Aoki, Junken; Weinreb, Robert N; Aihara, Makoto

    2018-02-01

    To compare the levels of autotaxin (ATX), lysophosphatidic acid (LPA), and lysophosphatidylcholine (LPC) in the aqueous humor (AH) of healthy control subjects with those of patients with different subtypes of glaucoma, and also to investigate the relationship of the ATX-LPA pathway with IOP and subtype of glaucoma. This study included 164 eyes of 164 consecutive cases of cataract and glaucoma surgery (37 healthy, 31 normal tension glaucoma, 49 primary open angle glaucoma, 28 secondary open angle glaucoma, and 19 exfoliation glaucoma). Aqueous levels of LPA, LPC, and ATX were quantified using liquid chromatography-tandem mass spectrometry and a two-site immunoenzymetric assay. The association between aqueous levels of ATX/LPA/LPC and IOP elevation in different glaucoma subtypes was investigated. The diagnostic values of indices of the ATX-LPA pathway were compared using receiver operating characteristic curve analysis. Notable increases in ATX/LPA/LPC levels in glaucoma patients were observed. The ATX-LPA pathway was significantly related to IOP elevation and the subtype of glaucoma, especially in SOAG and XFG patients, and the area under the curve was significant for discriminating glaucoma eyes from healthy eyes. Bioactive ATX/LPA/LPC concentrations were present in aqueous humor, and higher ATX and LPA concentrations were significantly correlated with IOP in all study subjects. Furthermore, the ATX-LPA pathway was significantly related to glaucoma subtype. These results reveal the potentially important role of the ATX-LPA pathway for IOP regulation in healthy subjects and glaucoma patients.

  9. The mechanism of timolol in lowering intraocular pressure. In the normal eye.

    Science.gov (United States)

    Coakes, R L; Brubaker, R F

    1978-11-01

    A single-drop, double-masked, randomized, placebo-controlled study of the mechanism of the ocular-pressure lowering property of timolol maleate, a beta-adrenergic blocker, was carried out in 23 normal subjects, using fluorophotometry. Timolol suppressed aqueous formation in all subjects. The range of suppression was 13% to 48%, with a mean +/- SD of 34% +/- 9%. The drug had no effect on anterior chamber volume or endothelial permeability to fluorescein and, apparently, had no effect on outflow resistance. No differences were observed between its effect on men and women or between eyes with light and dark irides.

  10. Burst pressure of super duplex stainless steel pipes subject to combined axial tension, internal pressure and elevated temperature

    International Nuclear Information System (INIS)

    Lasebikan, B.A.; Akisanya, A.R.

    2014-01-01

    The burst pressure of super duplex stainless steel pipe is measured under combined internal pressure, external axial tension and elevated temperature up to 160 °C. The experimental results are compared with existing burst pressure prediction models. Existing models are found to provide reasonable estimate of the burst pressure at room temperature but significantly over estimate the burst pressure at elevated temperature. Increasing externally applied axial stress and elevated temperature reduces the pressure capacity. - Highlights: • The burst pressure of super duplex steel is measured under combined loading. • Effect of elevated temperature on burst pressure is determined. • Burst pressure decreases with increasing temperature. • Existing models are reliable at room temperature. • Burst strength at elevated temperature is lower than predictions

  11. Elevated pretreatment blood pressure and IV thrombolysis in stroke.

    Science.gov (United States)

    Dirks, Maaike; Zonneveld, Thomas P; Dippel, Diederik W J; Nederkoorn, Paul J; van de Beek, Diederik; van Oostenbrugge, Robert J; Kruyt, Nyika D

    2015-04-07

    We investigated whether an active blood pressure-lowering strategy is associated with more patients receiving thrombolytics compared with a conservative "watch and measure" strategy, and assessed safety and functional outcome of these 2 treatment strategies. This is a post hoc analysis in 2 randomized controlled stroke trials, the PRACTISE (Promoting Acute Thrombolysis in Ischemic Stroke) and the PASS (Preventive Antibiotics in Stroke Study). We included all patients with elevated pretreatment blood pressure above 185/110 mm Hg at presentation but otherwise eligible for IV thrombolysis (IVT). The decision to use an active or conservative strategy was in accordance with local hospital treatment guidelines. The primary outcome was the proportion of patients treated with IVT. Secondary outcomes were (1) symptomatic intracranial hemorrhage (increased neurologic deficit with a concomitant hemorrhage on neuroimaging), (2) functional outcome at 3 months, and (3) the door-to-needle time. We included 224 patients, 66 (29%) received the active and 158 (71%) the conservative strategy. In the active group, 55 patients (83%) received thrombolytics vs 87 (55%) in the conservative group, an increase of 28% (95% confidence interval: 16%-40%). If only patients actually treated with IVT were considered, the rate of symptomatic intracranial hemorrhage was 7% in both groups. There was no difference in door-to-needle time. Active blood pressure lowering was associated with an increased proportion of patients treated with IVT compared with a conservative strategy, without a difference in symptomatic hemorrhage rate. © 2015 American Academy of Neurology.

  12. Validity of Tono-pachymetry for Measuring Corrected Intraocular Pressure in Non-surgical and Post-photorefractive Keratectomy Eyes.

    Science.gov (United States)

    Hahn, In Kyun; Kim, Jae Yong; Kim, Myoung Joon; Tchah, Hungwon; Moon, Chan Hee

    2017-02-01

    To assess the validity of central corneal thickness (CCT) and corrected intraocular pressure (IOP) values obtained by tono-pachymetry in non-surgical and post-photorefractive keratectomy (PRK) eyes. For the study, 108 young healthy participants and 108 patients who had PRK were enrolled. Measurements were randomly performed by tono-pachymetry, ultrasonic (US) pachymetry, and Goldmann applanation tonometry (GAT). CCT measurement by tono-pachymetry was compared to that of US pachymetry. The corrected IOP value obtained by tono-pachymetry was compared to that obtained by US pachymetry and GAT. The corrected IOP from US pachymetry and GAT was calculated using the identical compensation formula built into the tono-pachymetry. Bland-Altman plot and paired t -test were conducted to evaluate the between-method agreements. The mean CCT measurement using tono-pachymetry was significantly greater by 7.3 µm in non-surgical eyes ( p < 0.001) and 17.8 µm in post-PRK eyes ( p < 0.001) compared with US pachymetry. Differences were significant in both Bland-Altman plotand paired t -test. The mean difference of corrected IOP values obtained by tono-pachymetry and calculated from measurements by US pachymetry and GAT was 0.33 ± 0.87 mmHg in non-surgical eyes and 0.57 ± 1.08 mmHg in post-PRK eyes. The differences in the Bland-Altman plot were not significant. The CCT measurement determined using tono-pachymetrywas significantly thicker than that of US pachymetry. The difference in CCT was greater in post-PRK eyes than in non-surgical eyes. However, the corrected IOP value obtained by tono-pachymetry showed reasonable agreement with that calculated from US pachymetry and GAT measurements.

  13. Intraocular pressure in children: the effect of body position as assessed by Icare and Tono-Pen tonometers.

    Science.gov (United States)

    Dosunmu, Eniolami O; Marcus, Inna; Tung, Irene; Thiamthat, Warakorn; Freedman, Sharon F

    2014-12-01

    To explore the effect of body position (sitting vs supine) on intraocular pressure (IOP) in children, as assessed by the Icare PRO and the Tono-Pen. Prospective clinical study. Children with known or suspected glaucoma and those without glaucoma were recruited from the Duke Eye Center pediatric clinic. Subjects underwent tonometry in both eyes while upright (sitting), after instillation of topical anesthetic, with either the Icare PRO or the Tono-Pen first, and then the second instrument (order randomized). Goldmann applanation tonometry (GAT) was then performed by a clinician masked to the previous measurements. The subjects were then placed in the supine position for 5 minutes, and tonometry using the Icare PRO and the Tono-Pen was obtained, in the same order used when they were the sitting position. Enrolled were 47 children (94 eyes). Mean seated IOP for GAT, Icare PRO and Tono-Pen were 16.4 ± 4.2, 17.5 ± 3.5, and 18.0 ± 3.9 mm Hg, respectively. The mean supine IOP for the Icare PRO and Tono-Pen were 18.4 ± 4.5 and 18.8 ± 4.2 mm Hg, respectively. This rise was +0.9 ± 2.3 mm Hg for Icare PRO (P = 0.01) and +0.7 ± 1.8 mm Hg for Tono-Pen (P = 0.009), respectively. In children, Icare PRO tonometry correlates well with GAT in the sitting position, and with the Tono-Pen in both the sitting and supine positions. IOP rises when a child changes position from sitting to supine when measured by the Icare PRO or the Tono-Pen. However, the increase, which is less than 1 mm Hg, seems clinically insignificant and is unlikely to alter glaucoma management in children. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Correspondence of Tono-Pen intraocular pressure measurements performed at the central cornea and mid-peripheral cornea.

    Science.gov (United States)

    Sullivan-Mee, Michael; Pham, Fortsmith

    2004-01-01

    As the awareness of the influence of central corneal thickness (CCT) on Goldmann tonometry has increased, many publications have questioned the accuracy of Goldmann intraocular pressure (IOP) measurement. The Tono-Pen, because it indents a much smaller surface area when compared to a Goldmann probe, may be less affected by corneal thickness variations when compared with Goldmann tonometry. Forty human subjects with no history of refractive surgery participated in this study. The IOP of the right eye of each subject was measured with the Goldmann tonometer, the Tono-Pen at the central cornea, and the Tono-Pen at the mid-peripheral cornea. An ultrasonic DGH Pachette pachymeter was used to measure the central and mid-peripheral corneal thickness at the location of the IOP readings. Tono-Pen measurements at the central and mid-peripheral cornea highly correlated (r = 0.933), and did not significantly differ (p = 0.646). The IOP readings with the Goldmann tonometer (r= 0.406), the Tono-Pen at the central cornea (r = 0.453), and the Tono-Pen at the mid-peripheral cornea (r = 0.321) showed a positive correlation to corneal thickness. The Goldmann and Tono-Pen tonometers differed significantly in the measurement of IOP at the central cornea (p = 0.007), but were positively correlated (r = 0.674). The Tono-Pen IOP measurement at the central cornea highly approximated Tono-Pen IOP measurement at the mid-peripheral cornea. Furthermore, although not highly correlated, both the Goldmann and Tono-Pen tonometers showed a significantly positive correlation between IOP and corneal thickness measurements.

  15. Repeatability, reproducibility and agreement of intraocular pressure measurement in rabbits by the TonoVet and Tono-Pen.

    Science.gov (United States)

    Ma, Di; Chen, Chong-Bo; Liang, Jiajian; Lu, Zhihao; Chen, Haoyu; Zhang, Mingzhi

    2016-10-12

    Tono-Pen and TonoVet have been used in rabbits to measure intraocular pressure (IOP) and investigate the effect of IOP lowering therapies. Therefore, their reliability and accuracy are very important and deserve careful evaluation. Our results showed that the with-subject deviation (S w ) and intraclass correlation coefficient (ICC) of the TonoVet and Tono-Pen were 0.61 mmHg/0.83 mmHg and 0.97/0.94, respectively for intrasession repeatability. For intersession reproducibility, the Sw and ICC of TonoVet and Tono-Pen were 1.42 mmHg/1.66 mmHg and 0.73/0.67, respectively. For interoperator reproducibility, the S w and ICC of the TonoVet and Tono-Pen were 0.72 mmHg/1.11 mmHg and 0.91/0.82 respectively. Both TonoVet and Tono-Pen underestimated the IOP measured by manometry. The regression function was: y = 0.8249x + 0.1011 and y =0.6881x + 2.2290 for TonoVet and Tono-Pen, respectively. Our study suggests that both TonoVet and Tono-Pen had excellent intrasession repeatability and inter-operator reproducibility, but good intersession reproducibility. Both TonoVet and Tono-Pen correlated well with manometry, but underestimated the manometric IOP with presence of fixed and proportional biases. These factors should be considered when measuring IOP with Tono-Pen or TonoVet in rabbit eyes.

  16. Age-related association of refractive error with intraocular pressure in the Korea National Health and Nutrition Examination Survey.

    Science.gov (United States)

    Choi, Jin A; Han, Kyungdo; Park, Yong-Moon; Park, Chan Kee

    2014-01-01

    To investigate the distribution of intraocular pressure (IOP) and refractive errors according to age group in a representative sample of non-glaucomatous Korean adults. A total of 7,277 adults (≥ 19 years) who participated in the Korea National Health and Nutrition Examination Survey (KNHANES) from 2008 to 2011 underwent ophthalmic examination were divided into three groups according to age: the young- (19-39 years), middle- (40-59 years), and old- (≥ 60 years) age groups. Simple and multiple regression analyses between IOP and various parameters (including the refractive error) were conducted. The mean IOP of the total population was 14.0 ± 0.1 mmHg [young: 13.9 ± 0.1 mmHg; middle: 14.1 ± 0.1 mmHg; old: 13.8 ± 0.2 mmHg (P for trend = 0.085)]. Myopia and high myopia were more prevalent in the young- (70.8% and 16.1%, respectively), compared to the middle- (44.6% and 10.9%) and old- (8.9% and 2.2%) age groups. Univariate analysis in the total population showed that higher IOP was associated with myopic refractive error, the female gender, higher body mass index (BMI), diabetes, hypertension, and hypercholesterolemia (all Prefractive error, the female gender, higher BMI, hypercholesterolemia and diabetes (all Prefractive error was not significant (P = 0.828). In multiple linear regression analysis, similar significant relationships between the refractive error and IOP were found in the young- and middle-age groups (beta =  -0.08 and -0.12; P = 0.002 and refractive error was an independent predictor of higher IOP in non- glaucomatous eyes, and the association between refractive error and IOP differed according to age.

  17. Diurnal intraocular pressure changes in eyes affected with acute primary angle closure and fellow eyes after laser peripheral iridotomy.

    Science.gov (United States)

    Park, Han Seok; Kim, Joon Mo; Shim, Seong Hee; Kim, Hyun Tae; Bae, Jeong Hun; Choi, Chul Young; Park, Ki Ho

    2015-09-01

    To evaluate diurnal curves of intraocular pressure (IOP) in eyes affected with unilateral acute primary angle closure (APAC) after laser peripheral iridotomy (LPI), and fellow eyes. The medical records of 22 female patients (44 eyes) with unilateral APAC and LPI performed OU were reviewed along with those of 48 normal control subjects (48 eyes). None of the subjects used glaucoma medications after LPI. IOP was measured with a Goldman applanation tonometer during waking hours and in a sitting position every 2 h between 09:00 and 23:00. IOP profiles were compared including the means, peaks, trough IOPs, and IOP fluctuations of the affected, fellow, and normal eyes. The IOPs of the affected eyes were significantly higher than those of normal eyes at every time point measured, including peak and trough IOPs. The diurnal IOPs of fellow eyes were higher than those of normal eyes, though not significantly. There were no significant differences in IOP fluctuation between the affected, fellow, and normal eyes. IOP diurnal curves for APAC affected, fellow, and normal eyes were not statistically different (repeated measures ANOVA, p = 0.865). The mean coefficient of IOP in affected and fellow eyes ranged from 0.486 to 0.604. There were no clinically significant differences among the three groups in terms of IOP diurnal curves, and thus LPI did not have a significant effect on diurnal patterns of IOP. Though the diurnal IOPs of affected eyes after LPI was significantly higher than those of normal eyes, the IOP range was not acute.

  18. Noninvasive measurement of wave speed of porcine cornea in ex vivo porcine eyes for various intraocular pressures.

    Science.gov (United States)

    Zhou, Boran; Sit, Arthur J; Zhang, Xiaoming

    2017-11-01

    The objective of this study was to extend an ultrasound surface wave elastography (USWE) technique for noninvasive measurement of ocular tissue elastic properties. In particular, we aim to establish the relationship between the wave speed of cornea and the intraocular pressure (IOP). Normal ranges of IOP are between 12 and 22mmHg. Ex vivo porcine eye balls were used in this research. The porcine eye ball was supported by the gelatin phantom in a testing container. Some water was pour into the container for the ultrasound measurement. A local harmonic vibration was generated on the side of the eye ball. An ultrasound probe was used to measure the wave propagation in the cornea noninvasively. A 25 gauge butterfly needle was inserted into the vitreous humor of the eye ball under the ultrasound imaging guidance. The needle was connected to a syringe. The IOP was obtained by the water height difference between the water level in the syringe and the water level in the testing container. The IOP was adjusted between 5mmHg and 30mmHg with a 5mmHg interval. The wave speed was measured at each IOP for three frequencies of 100, 150 and 200Hz. Finite element method (FEM) was used to simulate the wave propagation in the corneal according to our experimental setup. A linear viscoelastic FEM model was used to compare the experimental data. Both the experiments and the FEM analyses showed that the wave speed of cornea increased with IOP. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Can the SENSIMED Triggerfish®lens data be used as an accurate measure of intraocular pressure?

    Science.gov (United States)

    Vitish-Sharma, Parveen; Acheson, Austin G; Stead, Richard; Sharp, John; Abbas, Ali; Hovan, Marta; Maxwell-Armstrong, Charles; Guo, Boliang; King, Anthony J

    2018-03-01

    The SENSIMED Triggerfish ® contact lens sensor (CLS) has an embedded micro-sensor that captures spontaneous circumferential changes at the corneoscleral junction and transmits them via an antenna to a device where these measurements are stored. During laparoscopic colorectal surgery, patients are placed in Trendelenburg position which has been shown to increase intraocular pressure (IOP). Laparoscopic colorectal surgery requires both pneumoperitoneum and Trendelenburg positioning; therefore, IOP can vary significantly. We aimed to assess whether circumferential changes in the corneoscleral area can be correlated to IOP changes measured using Tono-pen ® XL applanation tonometer during laparoscopic colorectal surgery. Patients undergoing laparoscopic colorectal resections were included. On the day of surgery, baseline IOP was taken and the SENSIMED Triggerfish ® CLS was then set up in one eye of the patient. During surgery (whilst under general anaesthetic), IOP measurements were taken in the contralateral eye using a Tono-pen ® XL applanation tonometer every hour and any time the table was moved to record the fluctuations of IOP during surgery and any association with position change. The timings of these readings were documented. Twenty patients were included in this study (six males, 14 females). Average age was 64.6 years (SD = 16.3). The fluctuation in IOP measured in the reference eye ranged between 6.3 and 46.7 mmHg. The mean correlation coefficient between CLS output measurements and these IOP measurements was r = 0.291 (95% CI). Our results showed a weak correlation between the SENSIMED Triggerfish ® CLS data output and IOP measurements taken using the Tono-pen ® XL applanation tonometer. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  20. Ex vivo and in vivo study of Kowa HA-2 applanation tonometer in the measurement of intraocular pressure in dogs

    Directory of Open Access Journals (Sweden)

    Silvia Franco Andrade

    2016-04-01

    Full Text Available The objective of this study was to evaluate the use of the Kowa HA-2 applanation tonometer in measuring intraocular pressure (IOP in dogs. Twenty eyes were used in an ex vivo study in which the calibration curve for manometry vs. tonometry was determined by artificially raising the IOP in 5 mmHg increments up to 60 mmHg (10-60 mmHg. Both eyes of 10 anesthetized dogs were studied in vivo to compare manometry vs. tonometry. In the ambulatory study, 168 healthy eyes, 74 eyes with glaucoma and 60 eyes with uveitis were evaluated by tonometry, which was performed with topical anesthesia and 1% fluorescein eye drops for the formation of fluorescein semicircles. The ex vivo study showed an excellent correlation coefficient (r2= 0.993 between the aneroid manometer and the Kowa HA-2 tonometer. In the in vivo study, there was no significant difference (P>0.05 between the IOP values by manometry and tonometry, showing the excellent accuracy of the Kowa HA-2 tonometer. In the ambulatory study using the Kowa HA-2 tonometer, the IOP values (mean±SD, in mmHg were 15.1±1.8 (12.0 – 20.0 for the healthy eyes, 25.2±4.0 (20.0 – 38.0 for glaucomatous eyes and 10.1±2.3 (5.0 – 13.7 for eyes with uveitis. There was a strong correlation between the IOP values obtained by direct ocular manometry and those from the Kowa HA-2 tonometer. In the ambulatory study, the IOP values measured by the tonometer were compatible for healthy eyes and for eyes with glaucoma or uveitis. We conclude that Kowa HA-2 applanation tonometer is accurate and practical for IOP measurement in dogs.

  1. Computing the influences of different Intraocular Pressures on the human eye components using computational fluid-structure interaction model.

    Science.gov (United States)

    Karimi, Alireza; Razaghi, Reza; Navidbakhsh, Mahdi; Sera, Toshihiro; Kudo, Susumu

    2017-01-01

    Intraocular Pressure (IOP) is defined as the pressure of aqueous in the eye. It has been reported that the normal range of IOP should be within the 10-20 mmHg with an average of 15.50 mmHg among the ophthalmologists. Keratoconus is an anti-inflammatory eye disorder that debilitated cornea unable to reserve the normal structure contrary to the IOP in the eye. Consequently, the cornea would bulge outward and invoke a conical shape following by distorted vision. In addition, it is known that any alterations in the structure and composition of the lens and cornea would exceed a change of the eye ball as well as the mechanical and optical properties of the eye. Understanding the precise alteration of the eye components' stresses and deformations due to different IOPs could help elucidate etiology and pathogenesis to develop treatments not only for keratoconus but also for other diseases of the eye. In this study, at three different IOPs, including 10, 20, and 30 mmHg the stresses and deformations of the human eye components were quantified using a Three-Dimensional (3D) computational Fluid-Structure Interaction (FSI) model of the human eye. The results revealed the highest amount of von Mises stress in the bulged region of the cornea with 245 kPa at the IOP of 30 mmHg. The lens was also showed the von Mises stress of 19.38 kPa at the IOPs of 30 mmHg. In addition, by increasing the IOP from 10 to 30 mmHg, the radius of curvature in the cornea and lens was increased accordingly. In contrast, the sclera indicated its highest stress at the IOP of 10 mmHg due to over pressure phenomenon. The variation of IOP illustrated a little influence in the amount of stress as well as the resultant displacement of the optic nerve. These results can be used for understanding the amount of stresses and deformations in the human eye components due to different IOPs as well as for clarifying significant role of IOP on the radius of curvature of the cornea and the lens.

  2. Surgical induced astigmatism correlated with corneal pachymetry and intraocular pressure: transconjunctival sutureless 23-gauge versus 20-gauge sutured vitrectomy in diabetes mellitus.

    Science.gov (United States)

    Shao, Yan; Dong, Li-Jie; Zhang, Yan; Liu, Hui; Hu, Bo-Jie; Liu, Ju-Ping; Li, Xiao-Rong

    2015-01-01

    To determine the difference of surgical induced astigmatism between conventional 20-gauge sutured vitrectomy and 23-gauge transconjunctival sutureless vitrectomy, and the influence of corneal pachymetry and intraocular pressure (IOP) on surgical induced astigmatism in diabetic patients. This retrospective, consecutive case series consisted of 40 eyes of 38 diabetic subjects who underwent either 20-gauge or 23-gauge vitrectomy. The corneal curvature and thickness were measured with Scheimpflug imaging before surgery and 1wk; 1, 3mo after surgery. We compared the surgical induced astigmatism (SIA) on the true net power in 23-gauge group with that in 20-gauge group. We determined the correlation between corneal thickness change ratio, IOP and SIA measured by Pentacam. The mean SIAs were 1.082±0.085 D (mean±SEM), 0.689±0.070 D and 0.459±0.063 D at postoperative 1wk; 1, 3mo respectively in diabetic subjects. The vitrectomy induced astigmatisms were declined significantly with time (F 2,36=33.629, P=0.000) postoperatively. The 23-gauge surgery group induced significantly less astigmatism than 20-gauge surgery group (F -1,37=11.046, P=0.020). Corneal thickness in diabetes elevated after surgery (F 3,78=10.532, P=0.000). The linear regression analysis at postoperatively 1wk went as: SIA=-4.519+4.931 change ratio (Port3) +0.026 IOP (R(2)=0.46, P=0.000), whereas the rate of corneal thickness change and IOP showed no correlation with the change of astigmatism at postoperatively 1 and 3mo. There are significant serial changes in both 20-gauge and 23-gauge group in diabetic subjects. 23-gauge induce less astigmatism than 20-gauge and become stable more rapidly than 20-gauge. The elevation of corneal thickness and IOP was associated with increased astigmatim at the early postoperative stage both in 23-gauge and 20-gauge surgery group.

  3. Prostaglandin F2alpha elevates blood pressure and promotes atherosclerosis

    DEFF Research Database (Denmark)

    Yu, Ying; Lucitt, Margaret B; Stubbe, Jane

    2009-01-01

    Little is known about prostaglandin F(2alpha) in cardiovascular homeostasis. Prostaglandin F(2alpha) dose-dependently elevates blood pressure in WT mice via activation of the F prostanoid (FP) receptor. The FP is expressed in preglomerular arterioles, renal collecting ducts, and the hypothalamus...... that exhibit mild polyuria and polydipsia. Atherogenesis is retarded by deletion of the FP, despite the absence of detectable receptor expression in aorta or in atherosclerotic lesions in Ldlr KOs. Although vascular TNF(alpha), inducible nitric oxide enzyme and TGF(beta) are reduced and lesional macrophages...... are depleted in the FP/Ldlr double KOs, this result reflects the reduction in lesion burden, as the FP is not expressed on macrophages and its deletion does not alter macrophage cytokine generation. Blockade of the FP offers an approach to the treatment of hypertension and its attendant systemic vascular...

  4. Analysis of the effects of non-supine sleeping positions on the stress, strain, deformation and intraocular pressure of the human eye

    Science.gov (United States)

    Volpe, Peter A.

    This thesis presents analytical models, finite element models and experimental data to investigate the response of the human eye to loads that can be experienced when in a non-supine sleeping position. The hypothesis being investigated is that non-supine sleeping positions can lead to stress, strain and deformation of the eye as well as changes in intraocular pressure (IOP) that may exacerbate vision loss in individuals who have glaucoma. To investigate the quasi-static changes in stress and internal pressure, a Fluid-Structure Interaction simulation was performed on an axisymmetrical model of an eye. Common Aerospace Engineering methods for analyzing pressure vessels and hyperelastic structural walls are applied to developing a suitable model. The quasi-static pressure increase was used in an iterative code to analyze changes in IOP over time.

  5. Travoprost with sofZia® preservative system lowered intraocular pressure of Japanese normal tension glaucoma with minimal side effects

    Directory of Open Access Journals (Sweden)

    Mizoue S

    2014-02-01

    Full Text Available Shiro Mizoue,1 Tadashi Nakano,2 Nobuo Fuse,3 Aiko Iwase,4 Shun Matsumoto,5 Keiji Yoshikawa6 On behalf of the IOP CHANGE Study Group7 1Department of Ophthalmology, Ehime University Graduate School of Medicine, Ehime, Japan; 2Department of Ophthalmology, Jikei University School of Medicine, Tokyo, Japan; 3Department of Integrative Genomics, Tohoku Medical Megabank Organization, Miyagi, Japan; 4Tajimi Iwase Eye Clinic, Gifu, Japan; 5Department of Ophthalmology, Tokyo Teishin Hospital, 6Yoshikawa Eye Clinic, Tokyo, Japan; 7IOP CHecked and Assessed in Normal tension Glaucoma by Exceptional Glaucomatologists Study Group, Japan Background: This study aimed to evaluate the effect of travoprost with sofZia® preservative system for lowering the intraocular pressure (IOP of Japanese normal tension glaucoma (NTG patients. Methods: In this prospective, multicenter, open-label study, Japanese NTG patients with baseline IOPs <20 mmHg were enrolled after three consecutive time measurements taken at screening and baseline visits. Travoprost with sofZia® was instilled once daily. Lowering effect on IOP, conjunctival hyperemia, superficial punctate keratopathy, and adverse events were examined at week 4, 8, and 12 after drug instillation. Results: One-hundred and three of the 107 enrolled patients (baseline IOP =15.2±2.0 mmHg [mean ± standard deviation] completed the study. The mean IOP value as well as percent reduction was significantly reduced at each visit after travoprost with sofZia® initiation (P<0.0001. The conjunctival hyperemia score was 1 or less throughout the study, though it increased significantly over time. No significant change was observed in superficial punctate keratopathy. The cumulative incidence of side effects such as eyelash changes, eyelid pigmentation, and deepening of the upper lid was 47.6%, 27.2%, and 16.5%, respectively. Conclusion: Travoprost preserved with sofZia® effectively lowered the IOP of Japanese NTG patients. It was

  6. Creep of Posidonia Shale at Elevated Pressure and Temperature

    Science.gov (United States)

    Rybacki, E.; Herrmann, J.; Wirth, R.; Dresen, G.

    2017-12-01

    The economic production of gas and oil from shales requires repeated hydraulic fracturing operations to stimulate these tight reservoir rocks. Besides simple depletion, the often observed decay of production rate with time may arise from creep-induced fracture closure. We examined experimentally the creep behavior of an immature carbonate-rich Posidonia shale, subjected to constant stress conditions at temperatures between 50 and 200 °C and confining pressures of 50-200 MPa, simulating elevated in situ depth conditions. Samples showed transient creep in the semibrittle regime with high deformation rates at high differential stress, high temperature and low confinement. Strain was mainly accommodated by deformation of the weak organic matter and phyllosilicates and by pore space reduction. The primary decelerating creep phase observed at relatively low stress can be described by an empirical power law relation between strain and time, where the fitted parameters vary with temperature, pressure and stress. Our results suggest that healing of hydraulic fractures at low stresses by creep-induced proppant embedment is unlikely within a creep period of several years. At higher differential stress, as may be expected in situ at contact areas due to stress concentrations, the shale showed secondary creep, followed by tertiary creep until failure. In this regime, microcrack propagation and coalescence may be assisted by stress corrosion. Secondary creep rates were also described by a power law, predicting faster fracture closure rates than for primary creep, likely contributing to production rate decline. Comparison of our data with published primary creep data on other shales suggests that the long-term creep behavior of shales can be correlated with their brittleness estimated from composition. Low creep strain is supported by a high fraction of strong minerals that can build up a load-bearing framework.

  7. Creep Behavior of Posidonia Shale at Elevated Pressure and Temperature

    Science.gov (United States)

    Rybacki, E.; Herrmann, J.; Wirth, R.; Dresen, G.

    2017-12-01

    Unconventional reservoir rocks are usually stimulated by repeated hydraulic fracturing operations. However, the production rate often decays with time that may arise from creep-induced fracture closure by proppant embedment. To examine experimentally the creep behavior of shales, we deformed immature carbonate-rich Posidonia shale at constant stress conditions and elevated temperatures between 50° and 200°C and confining pressures of 50 to 200 MPa. Samples showed transient creep in the semibrittle regime with high deformation rates at high differential stress, high temperature, and low confinement. Strain was mainly accommodated by deformation of the weak organic matter and phyllosilicates and by pore space reduction. At relatively low stress the samples deformed in the primary creep regime with continuously decelerating strain rate. The relation between strain and time can be described by an empirical power law equation, where the fitted parameters vary with temperature, pressure and stress. Our results suggest that healing of hydraulic fractures at low stresses by creep-induced proppant embedment is unlikely within a creep period of several years. At high differential stress (85-90% of the triaxial strength), as may be expected in situ at contact areas due to stress concentrations, the shale showed secondary creep, followed by tertiary creep until failure. In this regime, stress corrosion may induce microcrack propagation and coalescence. Secondary creep rates were also described by a power law that predicts faster fracture closure rates than for primary creep and likely contributes to production rate decline. Comparison of our data with published primary creep data on other shales suggest that the long-term creep behavior of shales can be correlated to their brittleness estimated from composition. Low creep strain is supported by a high fraction of strong minerals that can build up a load-bearing framework.

  8. Dust acoustic waves in complex plasmas at elevated pressure

    International Nuclear Information System (INIS)

    Filippov, A.V.; Starostin, A.N.; Tkachenko, I.M.; Fortov, V.E.

    2011-01-01

    The bi-Yukawa effective interaction potential with different screening constants is employed to calculate dust static correlation functions in the hyper-netted chain approximation and to generalize the theory of dust acoustic waves within the non-perturbative moment approach complemented by hydrodynamic considerations. For the bi-Yukawa interaction potential the sound speed becomes significantly wavenumber-dependent, an additional soft diffusion-like mode is predicted, and the static dielectric function is shown to take negative values. The results can be applied to non-equilibrium dusty plasmas at elevated pressure. -- Highlights: ► Bi-Yukawa interaction potential of dust particles with different screening lengths. ► Dust static correlation functions in the hyper-netted chain approximation. ► The moment and hydrodynamic approaches are in a good agreement at weak non-ideality. ► The dust acoustic wave phase and group velocities depend on the wavenumber. ► The moment approach hints the appearance of the diffusion-like soft mode.

  9. DDT in fuel air mixtures at elevated temperatures and pressures

    Science.gov (United States)

    Card, J.; Rival, D.; Ciccarelli, G.

    2005-11-01

    An experimental study was carried out to investigate flame acceleration and deflagration-to-detonation transition (DDT) in fuel air mixtures at initial temperatures up to 573 K and pressures up to 2 atm. The fuels investigated include hydrogen, ethylene, acetylene and JP-10 aviation fuel. The experiments were performed in a 3.1-m long, 10-cm inner-diameter heated detonation tube equipped with equally spaced orifice plates. Ionization probes were used to measure the flame time-of-arrival from which the average flame velocity versus propagation distance could be obtained. The DDT composition limits and the distance required for the flame to transition to detonation were obtained from this flame velocity data. The correlation developed by Veser et al. (run-up distance to supersonic flames in obstacle-laden tubes. In the proceedings of the 4th International Symposium on Hazards, Prevention and Mitigation of Industrial Explosions, France (2002)) for the flame choking distance proved to work very well for correlating the detonation run-up distance measured in the present study. The only exception was for the hydrogen air data at elevated initial temperatures which tended to fall outside the scatter of the hydrocarbon mixture data. The DDT limits obtained at room temperature were found to follow the classical d/λ = 1 correlation, where d is the orifice plate diameter and λ is the detonation cell size. Deviations found for the high-temperature data could be attributed to the one-dimensional ZND detonation structure model used to predict the detonation cell size for the DDT limit mixtures. This simple model was used in place of actual experimental data not currently available.

  10. Pigment dispersion syndrome associated with intraocular lens implantation: a new surgical technique

    Directory of Open Access Journals (Sweden)

    M Isabel Canut Jordana

    2010-11-01

    Full Text Available M Isabel Canut Jordana1, Daniel Pérez Formigó1, Rodrigo Abreu González2, Jeroni Nadal Reus11Barraquer Ophthalmology Centre, Barcelona, Spain; 2University Hospital of La Candelaria, Tenerife, SpainAims: We report the case of a myopic patient who, after intraocular lens transplant in the posterior chamber, suffered elevated intraocular pressure due to pigment dispersion, with recurrent episodes of blurred vision. The patient was treated with a new surgical technique that can avoid potential iridolenticular contact.Methods: Complete ophthalmologic examination and optical coherence tomography (OCT of the anterior segment were performed.Results: Contact between the pigmentary epithelium and the iris with an intraocular lens was revealed by utrasound biomicroscopy and OCT. In this case, Nd:YAG laser iridotomy and laser iridoplasty were not effective for iridolenticular separation and control of the pigment dispersion. We propose a new technique: stitches on the surface of the iris to obtain good iridolenticular separation and good intraocular pressure control.Conclusion: Stitches on the iris surface should be considered as optional therapy in pigmentary glaucoma secondary to intraocular lens implantation. This surgical technique can avoid potential iridolenticular contacts more definitively.Keywords: pigmentary glaucoma, intraocular lens, optical coherence tomography, laser

  11. Estudo do comportamento da pressão intra-ocular em pacientes diabéticos, hipertensos e normais (Projeto Glaucoma Analysis of the intraocular pressure in diabetics, hypertensive and normal patients (Glaucoma Project

    Directory of Open Access Journals (Sweden)

    Kenji Sakata

    2000-06-01

    Full Text Available Objetivo: Analisar os valores da pressão intra-ocular (PIO entre diferentes grupos de pacientes (diabéticos, hipertensos com ou sem retinopatia e a população normal. Métodos: Realizou-se a aferição da pressão intra-ocular (PIO em um total de 924 olhos de 482 pacientes com idade igual ou maior que 40 anos (x=56,70; dp=11,89 examinados segundo um protocolo de estudo que incluiu medida da PIO, pressão arterial e glicemia, além da fundoscopia. A determinação da PIO foi obtida pelo tonômetro de aplanação de "Goldmann" e a glicemia foi aferida por meio de tiras reativas (Dextrostix -- Bayer. Em seguida, os pacientes foram divididos em 7 (sete grupos: hipertensos, hipertensos com retinopatia, diabéticos, diabéticos com retinopatia, hipertensos e diabéticos, hipertensos e diabéticos com retinopatia e a população controle. Resultados: Pelo teste de ANOVA-uma via, numa distribuição normal no nível de significância de 5%, observou-se que o valor médio da PIO é significativamente maior no grupo de pacientes hipertensos sem retinopatia (média PIO=16,10, no grupo dos hipertensos com retinopatia (média PIO=16,33 e no grupo de diabéticos e hipertensos com retinopatia retinopatia (média PIO=16,95. Conclusões: Observou-se que o valor médio da PIO é progressivamente mais elevado conforme o tempo de evolução da doença hipertensiva e também quando esta se encontra associada à diabetes mellitus.Purpose: To correlate the values of intraocular pressure (IOP obtained by applanation tonometer (Haag-Streit, Bern, Switzerland in patients with diabetes mellitus (with or without diabetic retinopathy, hypertension (with or without hyper-tensive diabetic retinopathy and the normal population. Patients and Methods: Subjects participating in the Glau-coma Project (n = 924, 40 or more years old were examined according to standard protocols including IOP measu-rement, fundoscopy, blood pressure and glucose deter-mination. Patients were

  12. Intraocular pressure and aqueous humor flow during a euglycemic-hyperinsulinemic clamp in patients with type 1 diabetes and microvascular complications

    Directory of Open Access Journals (Sweden)

    Lane James T

    2010-06-01

    Full Text Available Abstract Background Microvascular complications, including retinopathy and nephropathy are seen with type 1 diabetes. It is unknown whether functional changes in aqueous humor flow or intraocular pressure (IOP develop in parallel with these complications. This study was designed to test the hypothesis that clinical markers of microvascular complications coexist with the alteration in aqueous humor flow and IOP. Methods Ten patients with type 1 diabetes and ten healthy age- and weight-matched controls were studied. Aqueous flow was measured by fluorophotometry during a hyperinsulinemic-euglycemic clamp (insulin 2 mU/kg/min. Intraocular pressure was measured by tonometry at -10, 90 and 240 minutes from the start of the clamp, and outflow facility was measured by tonography at 240 minutes. Results During conditions of identical glucose and insulin concentrations, mean aqueous flow was lower by 0.58 μl/min in the diabetes group compared to controls (2.58 ± 0.65 versus 3.16 ± 0.66 μl/min, respectively, mean ± SD, p = 0.07 but statistical significance was not reached. Before the clamp, IOP was higher in the diabetes group (22.6 ± 3.0 mm Hg than in the control group (19.3 ± 1.8 mm Hg, p = 0.01 but at 90 minutes into the clamp, and for the remainder of the study, IOP was reduced in the diabetes group to the level of the control group. Ocular pulse amplitude and outflow facility were not different between groups. Systolic blood pressure was significantly higher in the diabetes group, but diastolic and mean arterial pressures were not different. Conclusions We conclude that compared to healthy participants, patients with type 1 diabetes having microalbuminuria and retinopathy have higher IOPs that are normalized by hyperinsulinemia. During the clamp, a reduction in aqueous flow was not statistically significant.

  13. Comportamento da pressão intra-ocular segundo os efeitos cardiorrespiratórios e hemodinâmicos induzidos pela anestesia com desflurano, em cães submetidos à hipovolemia experimental Behavior of intraocular pressure according to cardiorespiratory and hemodynamic effects induced by desflurane in dogs subjected to experimental hypovolemia

    Directory of Open Access Journals (Sweden)

    Ivia Carmem Talieri

    2005-08-01

    Full Text Available OBJETIVOS: Observar o comportamento da pressão intra-ocular, segundo os efeitos cardiorrespiratórios e hemodinâmicos induzidos pela anestesia geral com desflurano, em cães submetidos à hipovolemia experimental. MÉTODOS: Foram utilizados 18 cães, machos e fêmeas, com peso entre 10 e 15 kg. A hipovolemia foi realizada retirando-se 40 ml de sangue/kg de peso. A seguir, a anestesia foi induzida com desflurano através de máscara facial, até que a intubação orotraqueal fosse permitida. A pressão intra-ocular foi medida por tonometria de aplanação. Valores para freqüência cardíaca, débito cardíaco, pressão arterial média, pressão venosa central e pressão parcial de CO2 ao final da expiração e freqüência respiratória foram mensurados. Os parâmetros da avaliação foram registrados após a instrumentalização e antes de qualquer outro procedimento (T0, quinze minutos depois da indução da hipovolemia experimental (T45 e após 30 minutos da indução anestésica (T75. RESULTADOS: A pressão intra-ocular apresentou relação direta somente com a pressão parcial de CO2 no final da expiração. CONCLUSÕES: Não foi possível estabelecer correlação entre alterações da pressão arterial média e da pressão venosa central com a pressão intra-ocular e houve relação direta entre os valores da pressão intra-ocular e os de ETCO2.PURPOSE: To observe the behavior of intraocular pressure according to the cardiopulmonary and hemodynamic effects induced by desflurane in dogs subjected to experimental hypovolemia. METHODS: Eighteen healthy male and female mongrel dogs, weighing between 10 and 15 kg were used. Hypovolemia was induced by withdrawal of 40 ml blood/kg body weight. Then anesthesia was induced with desflurane by mask until tracheal intubation was permitted. Intraocular pressure was measured with applanation tonometry. Heart rate, cardiac output, mean arterial pressure, central venous pressure, end-tidal concentration

  14. Hipertensão venosa episcleral idiopática unilateral em mulher jovem Unilateral idiopathic elevated episcleral venous pressure in a young woman

    Directory of Open Access Journals (Sweden)

    Marcelo Mendes Lavezzo

    2013-02-01

    Full Text Available O objetivo é relatar o caso de uma paciente de 33 anos, que veio ao Pronto Socorro de Oftalmologia apresentando queixa de redução da acuidade visual à esquerda, de caráter insidioso e progressivo, há dois anos. Ao exame oftalmológico, apresentava ingurgitamento dos vasos da conjuntiva bulbar, pressão intraocular muito elevada e nervo óptico com escavação total à esquerda. Foi submetida à campimetria computadorizada 24:2 WW e SITA-SWAP do olho direito, ambas com resultados dentro da normalidade. As tomografias de crânio e órbitas, bem como ultrassonografia com doppler do globo ocular, artérias oftálmicas e veias supraorbitárias não apresentavam anormalidades. Diante disso, aventou-se a hipótese diagnóstica de hipertensão venosa episcleral idiopática, um diagnóstico de exclusão, visto que patologias intracranianas e intraorbitárias haviam sido excluídas. Paciente foi tratada clinicamente com colírios hipotensores, com redução importante da pressão intraocular à esquerda, porém não o suficiente, evoluindo para trabeculectomia.The objective is to report a 33 year old female who came to the emergency room of Ophthalmology complaining of reduced visual acuity on the left eye, in a progressive and insidious way, about two years ago. In the ophthalmological examination, she presented dilated tortuous vessels in her left bulbar conjunctiva, very high intraocular pressure and increased cupping of the optic disc. SITA-SWAP and 24:2 computed perimetry were performed on the right eye, both within normal limits. CT scans of the skull and orbits, and ultrasonography of the eyeball and doppler of the ophthalmic artery and the supra-orbital veins had no abnormalities. Thus, it was suggested the possibility of idiopathic elevated episcleral venous pressure, an exclusion diagnosis, since intra-cranial and intraorbital pathologies were excluded. The patient was treated medically with hypotensive eyedrops, with significant reduction

  15. Avaliação da acuidade visual e da pressão intraocular no tratamento do edema macular diabético com triancinolona intravítrea Study of visual acuity and intraocular pressure in the treatment of macular diabetic edema with intravitreous triamcinolone

    Directory of Open Access Journals (Sweden)

    Marcussi Palata Rezende

    2010-04-01

    Full Text Available OBJETIVOS: Avaliar os efeitos do acetato de triancinolona intravítreo em pacientes com edema macular diabético difuso na acuidade visual e pressão intraocular. Relatar os possíveis efeitos adversos e analisar a possível relação da idade dos pacientes com as variações da acuidade visual e pressão intraocular. MÉTODOS: O ensaio clínico controlado incluiu 14 pacientes (28 olhos, sendo que 14 olhos receberam injeção de 4 mg de acetato de triancinolona intravítreo para o tratamento de edema macular diabético difuso. O grupo tratado foi comparado a um grupo controle de 14 olhos sem edema macular diabético difuso. O tempo de seguimento foi de três meses. RESULTADOS: Os picos de pressão intraocular >21 mmHg ocorreram em 28,57%, com diferença significante entre a pressão intraocular do grupo tratado com o grupo controle na primeira semana após o tratamento. A acuidade visual mostrou uma significativa melhora quando comparada com o grupo controle desde o segundo dia após o tratamento. Não houve associação entre a idade com as variações da acuidade visual e a pressão intraocular. CONCLUSÃO: O acetato de triancinolona intravítreo mostrou-se ser eficiente para melhorar a acuidade visual em pacientes com edema macular diabético difuso, nos primeiros três meses de tratamento. A incidência de hipertensão intraocular foi de 28,57%, podendo ser caracterizada como de fácil controle.PURPOSE: To evaluate the effect of intravitreal triamcinolone acetonide in patients with diffuse diabetic macular edema on the visual acuity and intraocular pressure. To report the potential adverse events and to analyze the potential relationship between age and visual acuity and intraocular pressure variability. METHODS: This clinical controlled study included 14 patients (28 eyes, 14 of the eyes received an intravitreal injection of 4 mg triamcinolone acetonide for the treatment of diabetic macular edema. The study group was compared to a control

  16. Comparison of intraocular pressures at different points in human's cornea before and after laser in situ keratomileusis with tono-pen tonometer.

    Science.gov (United States)

    Li, Xinyu; Li, Guigang; Liu, Lei; Li, Jing

    2011-02-01

    In order to explore the difference of intraocular pressure (IOP) at different points of cornea before and after laser in situ keratomileusis (LASIK), IOP was measured by Tono-Pen Tonometer at central cornea, pericentral cornea and limbus respectively and analyzed statistically. After LASIK, IOP was dropped significantly at central cornea and pericentral cornea (P0.05). There was no statistically significant difference in IOP at different points before LASIK (F=0.110, P=0.896), but statistically significant difference was found after LASIK (F=7.375, P=0.001). It was suggested that reliable IOP after LASIK could be obtained from the limbus by Tono-Pen tonometer.

  17. Effect of Riboflavin/UVA Collagen Cross-linking on Central Cornea, Limbus and Intraocular Pressure. Experimental Study in Rabbit Eyes.

    Science.gov (United States)

    Kozobolis, Vassilios; Gkika, Maria; Sideroudi, Haris; Tsaragli, Efthymia; Lydataki, Stylliani; Naoumidi, Irini; Giatromanolaki, Alexandra; Mikropoulos, Dimitrios; Teus, Miguel; Labiris, Georgios

    The Purpose of present study was to investigate the effect of riboflavin/ultraviolet-A-induced collagen cross-linking (CXL) on central cornea, limbus and intraocular pressure (IOP). This was an animal experimental study. The right corneas of 10 rabbits were ultraviolet-A irradiated (3 mW/cm2 for 30 minutes) after de-epithelialization and instillation of 0.1% riboflavin / 20% Dextran drops. Left corneas served as controls. Samples were examined histologically one month postoperatively. Before and after treatment, IOP measurements were recorded bilaterally. At central cornea of eyes underwent CXL keratocyte repopulation, normal arrangement of collagen fibres and a statistically significant change in fibres diameter were detected, compared to controls. At limbus area, there were not any significant histological differences after CXL. There was no statistically significant difference between pre- and postoperative IOP in all eyes.

  18. Relationship Between Intraocular Pressure and Parameters of Obesity in Korean Adults: The 2008-2010 Korea National Health and Nutrition Examination Survey.

    Science.gov (United States)

    Jang, Hyung-Deok; Kim, Do Hoon; Han, Kyungdo; Ha, Suk Gyu; Kim, Yang Hyun; Kim, Jae Woo; Park, Ji Young; Yoon, Su Jung; Jung, Dong Wook; Park, Sang Woon; Nam, Ga Eun

    2015-01-01

    To examine the associations of various parameters of obesity including adiposity with intraocular pressure (IOP) using nationally representative data of South Korean adults. This cross-sectional study analyzed the data from the 2008-2010 Korea National Health and Nutrition Examination Survey. A total of 15,271 subjects (6600 men and 8671 women) participated. Body mass index (BMI), waist circumference (WC), total body fat mass, and total and regional body fat percentage were measured as parameters of obesity. IOP showed positive linear associations with BMI, WC, total fat mass, and total and regional body fat percentages in men, and with BMI, WC, total fat mass, and trunk fat percentage in women after adjusting for confounding variables. Men with higher BMI, WC, total fat mass, and total and regional body fat percentages exhibited increasing trends in odd ratios for having IOP ≥ 18 mmHg after adjusting for all confounding factors (p for trend Korean men.

  19. Effects of premedication with sustained-release buprenorphine hydrochloride and anesthetic induction with ketamine hydrochloride or propofol in combination with diazepam on intraocular pressure in healthy sheep.

    Science.gov (United States)

    Gatson, Bonnie J; Pablo, Luisito; Plummer, Caryn E; Granone, Tiffany D

    2015-09-01

    To determine the effects of diazepam combined with ketamine hydrochloride or propofol for induction of anesthesia (IOA) following premedication with sustained-release buprenorphine hydrochloride (SRB) on intraocular pressure (IOP) in sheep. 20 healthy adult sheep. Diazepam with ketamine or propofol was given IV to each of 10 sheep after premedication with SRB (0.01 mg/kg, SC); after > 4 weeks, each sheep received the other induction combination with no premedication. For both eyes, IOPs were measured before premedication (if given), 10 minutes prior to (baseline) and immediately following administration of ketamine or propofol (time of IOA), after endotracheal intubation, and 5 minutes after IOA. Peak end-tidal P(CO2), globe position, and pupillary diameter were also analyzed. Data were not available for all sheep for all anesthetic episodes. Propofol-diazepam administration alone had no significant effect on IOP, whereas there was a significant decrease in IOP immediately following ketamine-diazepam administration alone. At 5 minutes after ketamine-diazepam administration, SRB-premedicated sheep had significantly higher IOP than unpremedicated sheep. Intraocular pressure was significantly higher at baseline, at intubation, and 5 minutes after IOA in SRB-premedicated sheep receiving propofol-diazepam, compared with unpremedicated sheep. Peak end-tidal P(CO2) at intubation was significantly higher in SRB-premedicated sheep. For sheep receiving either anesthetic treatment, IOPs did not differ significantly with or without SRB premedication. Globe position or pupillary diameter and IOP were not significantly related at any time point. Results suggested that both ketamine-diazepam and propofol-diazepam combinations were suitable for IOA without increasing IOP in sheep. The use of SRB should be avoided in sheep when increases in IOP are undesirable.

  20. Laser ignition of liquid petroleum gas at elevated pressures

    Science.gov (United States)

    Loktionov, E.; Pasechnikov, N.; Telekh, V.

    2017-11-01

    Recent development of laser spark plugs for internal combustion engines have shown lack of data on laser ignition of fuel mixtures at multi-bar pressures needed for laser pulse energy and focusing optimisation. Methane and hydrogen based mixtures are comparatively well investigated, but propane and butane based ones (LPG), which are widely used in vehicles, are still almost unstudied. Optical breakdown thresholds in gases decrease with pressure increase up to ca. 100 bar, but breakdown is not a sufficient condition for combustion ignition. So minimum ignition energy (MIE) becomes more important for combustion core onset, and its dependency on mixture composition and pressure has several important features. For example, unlike breakdown threshold, is poorly dependent on laser pulse length, at least in pico- and to microsecond range. We have defined experimentally the dependencies of minimum picosecond laser pulse energies (MIE related value) needed for ignition of LPG based mixtures of 1.0 to 1.6 equivalence ratios and pressure of 1.0 to 3.5 bar. In addition to expected values decrease, low-energy flammability range broadening has been found at pressure increase. Laser ignition of LPG in Wankel rotary engine is reported for the first time.

  1. MILD combustion for hydrogen and syngas at elevated pressures

    Science.gov (United States)

    Huang, Mingming; Zhang, Zhedian; Shao, Weiwei; Xiong, Yan; Lei, Fulin; Xiao, Yunhan

    2014-02-01

    As gas recirculation constitutes a fundamental condition for the realization of MILD combustion, it is necessary to determine gas recirculation ratio before designing MILD combustor. MILD combustion model with gas recirculation was used in this simulation work to evaluate the effect of fuel type and pressure on threshold gas recirculation ratio of MILD mode. Ignition delay time is also an important design parameter for gas turbine combustor, this parameter is kinetically studied to analyze the effect of pressure on MILD mixture ignition. Threshold gas recirculation ratio of hydrogen MILD combustion changes slightly and is nearly equal to that of 10 MJ/Nm3 syngas in the pressure range of 1-19 atm, under the conditions of 298 K fresh reactant temperature and 1373 K exhaust gas temperature, indicating that MILD regime is fuel flexible. Ignition delay calculation results show that pressure has a negative effect on ignition delay time of 10 MJ/Nm3 syngas MILD mixture, because OH mole fraction in MILD mixture drops down as pressure increases, resulting in the delay of the oxidation process.

  2. Intraocular pathology

    International Nuclear Information System (INIS)

    Mafee, M.F.; Resnick, K.; Jampol, L.; Kaufman, L.

    1991-01-01

    This paper reports that this study was undertaken to evaluate the role of gadolinium-enhanced MR imaging in evaluating patients with intraocular pathology. In 21 patients with uveal melanomas (n = 10), melanocytoma (n = 1), choroidal hemangiomas (n = 4), bilateral uveal lymphoma (n = 1), choroidal detachment (n = 1), or retinoblastomas (n = 3), we attempted MR imaging of the eye by using a 1.5-T GE signa unit. T2-weighted images and pre- and postgadolinium T1-weighted MR images were obtained. Uveal melanomas demonstrated moderate homogeneous or inhomogeneous intensity with gadolinium enhancement. In some patients, associated hemorrhage in the subretinal space behaved identical to melanoma on T1- and T2-weighted images. In these cases, gadolinium clearly demonstrated enhancement only with the tumor. Choroidal hemangiomas, unlike melanomas, were hyperintense on T2-weighted images and demonstrated intense homogeneous enhancement on gadolinium-enhanced MR images. Retinoblastomas appeared like uveal melanomas on MR images

  3. Comparative Autoignition Trends in Butanol Isomers at Elevated Pressure

    KAUST Repository

    Weber, Bryan W.

    2013-03-21

    Autoignition experiments of stoichiometric mixtures of s-, t-, and i-butanol in air have been performed using a heated rapid compression machine (RCM). At compressed pressures of 15 and 30 bar and for compressed temperatures in the range 715-910 K, no evidence of a negative temperature coefficient region in terms of ignition delay response is found. The present experimental results are also compared with previously reported RCM data of n-butanol in air. The order of reactivity of the butanols is n-butanol > s-butanol ≈ i-butanol > t-butanol at the lower pressure but changes to n-butanol > t-butanol > s-butanol > i-butanol at higher pressure. In addition, t-butanol shows preignition heat release behavior, which is especially evident at higher pressures. To help identify the controlling chemistry leading to this preignition heat release, off-stoichiometric experiments are further performed at 30 bar compressed pressure, for t-butanol at φ = 0.5 and φ = 2.0 in air. For these experiments, higher fuel loading (i.e., φ = 2.0) causes greater preignition heat release (as indicated by greater pressure rise) than the stoichiometric or φ = 0.5 cases. Comparison of the experimental ignition delays with the simulated results using two literature kinetic mechanisms shows generally good agreement, and one mechanism is further used to explore and compare the fuel decomposition pathways of butanol isomers. Using this mechanism, the importance of peroxy chemistry in the autoignition of the butanol isomers is highlighted and discussed. © 2013 American Chemical Society.

  4. Deformation Behavior of Thin Lubricant Films at Elevated Pressure.

    Science.gov (United States)

    1994-12-01

    Polymers, R. N. Haward , Ed., John Wiley & Sons, (1973) 279-339. 25. P.W. Bridgman, The Physics of High Pressure, Dover, N.Y. (1970). 26. C.W. Burham... John Wiley & Sons (1987). 10. J.K. Appeldoorn, E.H. Okrent and W. Phillippoff, "Viscosity and Elasticity at High Pressures and High Shear Rates," Proc...Investigations into Shear Localization in Operating Concentrated Contact," Proc. 19th Leeds-Lyon Symposium (1992). 42. John Harris, Rheology and Non-Newtonian

  5. Prevalence of obesity and elevated blood pressure among bankers ...

    African Journals Online (AJOL)

    The aim of this study was to determine the prevalence of obesity and hypertension among bankers in Lagos State, Nigeria. Methods: Blood pressure, body mass index (BMI) and waist circumference were measured in 260 professional bankers from 56 bank branches in Lagos. Results: The mean age of the respondents was ...

  6. Perioperative changes of the intraocular pressure during the treatment of epiretinal membrane by using 25- or 27-gauge sutureless vitrectomy without gas tamponade.

    Science.gov (United States)

    Takashina, Hirotsugu; Watanabe, Akira; Tsuneoka, Hiroshi

    2017-01-01

    The purpose of this study was to compare perioperative intraocular pressures (IOPs) in 25- or 27-gauge microincision vitrectomy surgery (MIVS) and to evaluate the stability of postoperative sclerotomy closure. This is a retrospective review of 147 eyes treated for epiretinal membrane by using 25- or 27-gauge MIVS as the initial vitrectomy (25-gauge phacovitrectomy [25-P group]: 73 eyes, 25-gauge vitrectomy alone [25-A group]: 15 eyes, 27-gauge phacovitrectomy [27-P group]: 47 eyes, and 27-gauge vitrectomy alone [27-A group]: 12 eyes). Statistical analyses of perioperative IOPs on preoperative day (PreOp), postoperative day (POD)1, POD2, postoperative week 1, and postoperative month 1 were performed. All self-sealing sclerotomies were obtained without gas tamponade at the end of surgery. Also, no significant differences were noted in the age and axial length among the 4 groups and in the surgical time between 25-P and 27-P groups and between 25-A and 27-A groups. Significant decreases in IOP were found at POD1 and POD2 in the 25-P, 25-A, and 27-P groups compared with PreOP, but not in the 27-A group. Even though surgeons confirm that there is no leakage from sutureless sclerotomy and that a normal IOP is preserved at the end of 25- or 27-gauge MIVS, there is a possibility of postoperative sclerotomy leakage on the day of the surgery. Furthermore, postoperative sclerotomy self-sealing of the MIVS in previous intraocular lens implantation cases is considered to be acquired easily than that in phacovitrectomy.

  7. Variação da pressão intraocular após teste submáximo de força no treinamento resistido Intraocular pressure variation after submaximal strength test in resistance training

    Directory of Open Access Journals (Sweden)

    Marcelo Conte

    2009-06-01

    Full Text Available OBJETIVO: Verificar a variação da pressão intraocular (PIO decorrente da aplicação do teste de predição para uma repetição máxima (1RM. MÉTODOS: Foram avaliados em estudo observacional 145 calouros (22,04 ± 4,17 anos; de ambos os sexos do curso de Educação Física da Escola Superior de Educação Física de Jundiaí (ESEFJ. Os critérios de exclusão foram: opacidade de meios, alteração de globo ocular ou ausência de globo ocular. Todos os participantes assinaram o Termo de Consentimento Livre e Esclarecido. A avaliação da PIO foi determinada por duas medidas consecutivas com o tonômetro de Perkins: i pré-teste: antes do teste de 1RM e ii pós-teste: logo após a realização do teste. O teste de 1RM consistiu em predizer o valor de uma repetição máxima através de repetições até a fadiga. Foram utilizados os seguintes exercícios resistidos: supino, pulley dorsal, desenvolvimento, rosca direta e leg press 45º. Como procedimento estatístico foi empregado o teste "t" de Student pareado. RESULTADOS: Ocorreu redução da PIO após a realização do teste de predição de 1RM: 13,48 ± 3,32 vs.10,20 ± 3,72 mmHg (pPURPOSE: To verify the intraocular pressure (IOP after sub-maximal strength test. METHODS: 145 Physical Education freshmen (22.04 ± 4.17 years old; female and male from Superior Physical Education School of Jundiaí (ESEFJ were evaluated in an observacional study. The exclusion criteria were: media opacity and eyeball absence or changes. All subjects agreed to take part in this research and signed up the Informed Consent. IOP was measured by Perkins tonometer: i pretest: just before the submaximal strength test performance and ii post-test: immediately after the strength test. The strength test consisted in the one-repetition-maximum-assessment through repetition until fatigue. Resistance training exercises such as bench press, pulley dorsal high, shoulder press, arm curl and leg press 45º were performed

  8. A pitfall in the measurement of arterial blood pressure in the ischaemic limb during elevation

    DEFF Research Database (Denmark)

    Bülow, J; Jelnes, Rolf

    1987-01-01

    In order to evaluate if elevation of the ischaemic limb above heart level is an alternative to the conventionally applied method with external counterpressure for estimation of skin perfusion pressure, femoral and popliteal artery pressures were measured directly in eight patients with occlusion ...... extremity cannot be determined non-invasively by elevation of the extremity, probably due to collapse of segments of the vascular bed increasing the vascular resistance considerably....

  9. Elevated blood pressure among primary school children in Dar es salaam, Tanzania: prevalence and risk factors.

    Science.gov (United States)

    Muhihi, Alfa J; Njelekela, Marina A; Mpembeni, Rose N M; Muhihi, Bikolimana G; Anaeli, Amani; Chillo, Omary; Kubhoja, Sulende; Lujani, Benjamin; Maghembe, Mwanamkuu; Ngarashi, Davis

    2018-02-13

    Whilst the burden of non-communicable diseases is increasing in developing countries, little data is available on blood pressure among Tanzanian children. This study aimed at determining the blood pressure profiles and risk factors associated with elevated blood pressure among primary school children in Dar es Salaam, Tanzania. We conducted a cross sectional survey among 446 children aged 6-17 years from 9 randomly selected primary schools in Dar es Salaam. We measured blood pressure using a standardized digital blood pressure measuring machine (Omron Digital HEM-907, Tokyo, Japan). We used an average of the three blood pressure readings for analysis. Elevated blood pressure was defined as average systolic or diastolic blood pressure ≥ 90th percentile for age, gender and height. The proportion of children with elevated blood pressure was 15.2% (pre-hypertension 4.4% and hypertension 10.8%). No significant gender differences were observed in the prevalence of elevated BP. Increasing age and overweight/obese children were significantly associated with elevated BP (p = 0.0029 and p < 0.0001) respectively. Similar associations were observed for age and overweight/obesity with hypertension. (p = 0.0506 and p < 0.0001) respectively. In multivariate analysis, age above 10 years (adjusted RR = 3.63, 95% CI = 1.03-7.82) was significantly and independently associated with elevated BP in this population of school age children. We observed a higher proportion of elevated BP in this population of school age children. Older age and overweight/obesity were associated with elevated BP. Assessment of BP and BMI should be incorporated in school health program in Tanzania to identify those at risk so that appropriate interventions can be instituted before development of associated complications.

  10. Measurement of local void fraction at elevated temperature and pressure

    International Nuclear Information System (INIS)

    Duncan, D.; Trabold, T.A.

    1993-03-01

    Significant advances have recently been made in analytical and computational methods for the prediction of local thermal-hydraulic conditions in gas/liquid two-phase flows. There is, however, a need for extensive experimental data, for the dual purposes of constitutive relation development and code qualification. There is especially true of systems involving complicated geometries and/or extreme flow conditions for which little, if any, applicable information exists in the open literature. For the tests described in the present paper, a novel electrical probe has been applied to measure the void fraction in atmospheric pressure air/water flows, and steam/water mixtures at high temperature and pressure. The data acquired in the latter experiments are compared with the results of a one-dimensional two-fluid computational analysis

  11. Thermodynamic and acoustic properties of (heptane + dodecane) mixtures under elevated pressures

    International Nuclear Information System (INIS)

    Dzida, Marzena; Cempa, Magdalena

    2008-01-01

    The speed of sound in (heptane + dodecane) mixtures was measured over the whole concentration range at pressures up to 101 MPa and within the temperature range from (293 to 318) K. The density of (heptane + dodecane) was measured in the whole composition range under atmospheric pressure and at temperatures from (293 to 318) K. The densities and heat capacities of these binaries at the same temperatures were calculated for pressures up to 100 MPa from the speeds of sound under elevated pressures together with the densities and heat capacities at atmospheric pressure. The effects of pressure and temperature on the excess molar volume and the excess molar heat capacity are discussed

  12. Elevated Mean Airway Pressure and Central Venous Pressure in the First Day of Mechanical Ventilation Indicated Poor Outcome.

    Science.gov (United States)

    Long, Yun; Su, Longxiang; Zhang, Qing; Zhou, Xiang; Wang, Hao; Cui, Na; Chai, Wenzhao; Wang, Xiaoting; Rui, Xi; Liu, Dawei

    2017-05-01

    The relationship between respiratory mechanical parameters and hemodynamic variables remains unclear. This study was performed to determine whether mean airway pressure and central venous pressure in the first day of mechanical ventilation are associated with patient outcomes. Retrospective first 24-hour comparison during ICU stay. The Department of Critical Care Medicine of Peking Union Medical College Hospital. Patients with mechanical ventilation. None. The clinical data of patients who received mechanical ventilation, especially respiratory and hemodynamic data, were collected and analyzed. In terms of the hemodynamic and perfusion data, the nonsurvivors group (177/2,208) had higher heart rate, respiratory rate, central venous pressure, and lactates and a lower perfusion index and P(v-a)CO2 (p mechanical ventilation, patients with elevated mean airway pressure and elevated central venous pressure had worse outcomes.

  13. Measurements and modeling of VLLE at elevated pressures

    DEFF Research Database (Denmark)

    Laursen, Torben

    and pure component calibration. Samples from the different liquid phases in the high-pressure cell is taken using a moveable needle. The systems investigated have been a combination of the components: CO2, N2, di-methyl ether (DME), water, methanol, ethanol and 1-propanol. 41 isotherms have been measured...... has traditionally been considered very time consuming. This work aims at developing and operating an equipment which allows routine measurements of both VLE and VLLE, in the temperature range of 25-45°C and pressure range of 1-100 bar. This has been done by taking advantage of on-line sampling...... and of these 18 were VLLE systems and 32 have not previously been published. Some of the experimental results have been modelled using an equation of state, SRK combined with the MHV1 mixing rule for the a-parameter and the NRTL model for the Gibbs excess energy. The Mathias-Copeman model was used...

  14. A 5.2GHz, 0.5mW RF powered wireless sensor with dual on-chip antennas for implantable intraocular pressure monitoring

    KAUST Repository

    Arsalan, Muhammad

    2013-06-01

    For the first time a single chip implantable wireless sensor system for Intraocular Pressure Monitoring (IOPM) is presented. This system-on-chip (SoC) is battery-free and harvests energy from incoming RF signals. The chip is self-contained and does not require external components or bond wires to function. This 1.4mm3 SoC has separate 2.4GHz-transmit and 5.2GHz-receive antennas, an energy harvesting module, a temperature sensor, a 7-bit TIQ Flash ADC, a 4-bit RFID, a power management and control unit, and a VCO transmitter. The chip is fabricated in a standard 6-metal 0.18μm CMOS process and is designed to work with a post-processed MEMS pressure sensor. It consumes 513μW of peak power and when implanted inside the eye, it is designed to communicate with an external reader using on-off keying (OOK). © 2013 IEEE.

  15. Sensory stimulation for lowering intraocular pressure, improving blood flow to the optic nerve and neuroprotection in primary open-angle glaucoma.

    Science.gov (United States)

    Rom, Edith

    2013-12-01

    Primary open-angle glaucoma is a group of optic neuropathies that can lead to irreversible blindness. Sensory stimulation in the form of acupuncture or ear acupressure may contribute to protecting patients from blindness when used as a complementary method to orthodox treatment in the form of drops, laser or surgery. The objective of this article is to provide a narrative overview of the available literature up to July 2012. It summarises reported evidence on the potential beneficial effects of sensory stimulation for glaucoma. Sensory stimulation appears to significantly enhance the pressure-lowering effect of orthodox treatments. Studies suggest that it may also improve blood flow to the eye and optic nerve head. Furthermore, it may play a role in neuroprotection through regulating nerve growth factor and brain-derived neurotrophic factor and their receptors, thereby encouraging the survival pathway in contrast to the pathway to apoptosis. Blood flow and neuroprotection are areas that are not directly influenced by orthodox treatment modalities. Numerous different treatment protocols were used to investigate the effect of sensory stimulation on intraocular pressure, blood flow or neuroprotection of the retina and optic nerve in the animal model and human pilot studies. Objective outcomes were reported to have been evaluated with Goldmann tonometry, Doppler ultrasound techniques and electrophysiology (pattern electroretinography, visually evoked potentials), and supported with histological studies in the animal model. Taken together, reported evidence from these studies strongly suggests that sensory stimulation is worthy of further research.

  16. The distribution of intraocular pressure and associated systemic factors in a Korean population: the Korea National Health and Nutrition Examination Survey.

    Science.gov (United States)

    Kim, Mi Jeung; Park, Ki Ho; Kim, Chan Yun; Jeoung, Jin Wook; Kim, Seok Hwan

    2014-11-01

    To investigate the distribution of intraocular pressure (IOP) and its associated factors in a large Korean population based on the data from the nationwide cross-sectional survey. We obtained 2009-2010 data from the Korea National Health and Nutrition Examination Survey (KNHANES) (n = 17 901). After excluding individuals under 19 years of age, a total of 13 431 subjects were enrolled. All participants completed a comprehensive questionnaire and underwent an ocular examination including measurement of IOP by Goldmann applanation tonometry, as well as a systemic evaluation including blood pressure measurements, anthropometry and blood tests. The mean IOP in the right eye was 13.99 ± 2.75 mmHg, and in the left eye, 13.99 ± 2.75 mmHg, representing no significant bilateral difference. There was, however, a significant difference between males (14.19 ± 2.78 mmHg) and females (13.79 ± 2.70 mmHg) (p 0.05). In the general Korean population, IOP increases with male sex and increasing myopia. Further, IOP is significantly correlated with systemic factors relating to cardiovascular disease and metabolic syndrome. © 2014 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  17. Using Smartphone Pressure Sensors to Measure Vertical Velocities of Elevators, Stairways, and Drones

    Science.gov (United States)

    Monteiro, Martín; Martí, Arturo C.

    2017-01-01

    We measure the vertical velocities of elevators, pedestrians climbing stairs, and drones (flying unmanned aerial vehicles), by means of smartphone pressure sensors. The barometric pressure obtained with the smartphone is related to the altitude of the device via the hydrostatic approximation. From the altitude values, vertical velocities are…

  18. Intraocular Surgery in Kyphosis: An Easier Approach

    Directory of Open Access Journals (Sweden)

    Karanjit S. Kooner

    2013-06-01

    Full Text Available We describe a 49-year-old man with advanced kyphosis and dense cataract, who could only recline to about 40° from the vertical axis despite a maximal reverse Trendelenburg position and pillows under the head, neck, shoulders and knees. With a single corneal retraction suture at 6 o'clock, the eye could be rotated horizontally, which enabled the surgeon to perform a complex cataract surgery despite prior glaucoma shunt, posterior synechiae, a small pupil and the need to stain the capsule. As the eye can be brought into any desired position with a retraction suture, patients with kyphosis or other conditions that prevent them from assuming a supine position can still have safe intraocular procedures. This maneuver reduces the need to tilt patients to an uncomfortable position that may cause pain, increased breathing difficulty and elevated posterior vitreous pressure.

  19. Elevated temperature and high pressure large helium gas loop

    International Nuclear Information System (INIS)

    Sakasai, Minoru; Midoriyama, Shigeru; Miyata, Toyohiko; Nakase, Tsuyoshi; Izaki, Makoto

    1979-01-01

    The development of high temperature gas-cooled reactors especially aiming at the multi-purpose utilization of nuclear heat energy is carried out actively in Japan and West Germany. In Japan, the experimental HTGR of 50 MWt and 1000 deg C outlet temperature is being developed by Japan Atomic Energy Research Institute and others since 1969, and the development of direct iron-making technology utilizing high temperature reducing gas was started in 1973 as the large project of Ministry of Internalional Trade and Industry. Kawasaki Heavy Industries, Ltd., Has taken part in these development projects, and has developed many softwares for nuclear heat design, system design and safety design of nuclear reactor system and heat utilization system. In hardwares also, efforts have been exerted to develop the technologies of design and manufacture of high temperature machinery and equipments. The high temperature, high pressure, large helium gas loop is under construction in the technical research institute of the company, and it is expected to be completed in December, 1979. The tests planned are that of proving the dynamic performances of the loop and its machinery and equipments and the verification of analysis codes. The loop is composed of the main circulation system, the objects of testing, the helium gas purifying system, the helium supplying and evacuating system, instruments and others. (Kako, I.)

  20. Pressure buffering by the tympanic membrane. In vivo measurements of middle ear pressure fluctuations during elevator motion.

    Science.gov (United States)

    Padurariu, Simona; de Greef, Daniël; Jacobsen, Henrik; Nlandu Kamavuako, Ernest; Dirckx, Joris J; Gaihede, Michael

    2016-10-01

    The tympanic membrane (TM) represents a pressure buffer, which contributes to the overall pressure regulation of the middle ear (ME). This buffer capacity is based on its viscoelastic properties combined with those of the attached ossicular chain, muscles and ligaments. The current work presents a set of in vivo recordings of the ME pressure variations normally occurring in common life: elevator motion. This is defined as a situation of smooth ambient pressure increase or decrease on a limited range and at a low rate of pressure change. Based on these recordings, the purpose was a quantitative analysis of the TM buffer capacity including the TM compliance. The pressure changes in seven normal adult ME's with intact TM's were continuously recorded directly inside the ME cavity during four different elevator trips using a high precision instrument. The TM buffer capacity was determined by the ratio between the changes in ME and the ambient pressure. Further, the ME volumes were calculated by Boyle's Law from pressure recordings during inflation-deflation tests; subsequently the TM compliance could also be calculated. Finally, the correlation between the ME volume and buffer function was determined. Twenty-one elevator trips could be used for the analysis. The overall mean TM pressure buffering capacity was 23.3% (SEM = 3.4), whereas the mean overall compliance was 28.9 × 10 -3  μL/Pa (SEM = 4.8). A strong negative linear correlation was found between the TM buffer capacity and the ME volumes (R 2  = 0.92). These results were in fair agreement with the literature obtained in clinical as well as temporal bone experiments, and they provide an in vivo reference for the normal ME function as well as for ME modeling. The TM buffer capacity was found more efficient in smaller mastoids. Possible clinical implications are discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Associação entre dois diferentes tipos de estrangulamento com a variação da pressão intraocular em atletas de jiu-jitsu Association between two different types of strangling and intraocular pressure variation in jiu-jitsu athletes

    Directory of Open Access Journals (Sweden)

    Marinho Jorge Scarpi

    2009-06-01

    Full Text Available OBJETIVO: Verificar a associação entre dois diferentes tipos de estrangulamento com a variação da pressão intraocular em atletas de jiu-jitsu. MÉTODO: Estudo observacional em grupo de 9 atletas de jiu-jitsu, com mínimo 6 meses de treinamento, sexo masculino, idades entre 20 e 30 anos, sem presença de lesões físicas e do bulbo ocular. Buscou-se associação entre a variação da pressão intraocular e os estrangulamentos Frontal da Guarda (E1 e Frontal da Montada (E2. A pressão intraocular foi determinada com o tonômetro de Perkins, inicialmente sem que o atleta tivesse realizado atividade física nas 24 horas antecedentes e após cada golpe. Realizou-se medidas da pressão intraocular por 12 minutos, uma a cada 3 minutos de recuperação (R1; R2; R3; R4, com o indivíduo deitado. Como procedimento estatístico foi empregado o teste ANOVA e o pós-teste de Bonferroni. RESULTADOS: Ocorreu redução significativa da pressão intraocular em ambos os olhos durante a situação E2 comparada a E1 em todos os momentos da aferição de recuperação: R1 (OD: 8,22 ± 1,39 vs.11,33 ± 2,00 / OE: 8,55 ± 1,23 vs. 11,88 ± 1,90, R2 (OD: 8,44 ± 1,87 vs.10,22 ± 2,53 / OE: 9,00 ± 1,80 vs. 10,44 ± 2,35, R3 (OD: 8,44 ± 1,74 vs.9,78 ± 2,54 / OE: 8,55 + 1,42 vs. 10,33 ± 1,93 todos com pPURPOSE: To verify the association between two different types of strangling with intraocular pressure variation in jiu-jitsu athletes. METHODS: An observational study was performed on 9 athletes of jiu-jitsu, with at least 6 month of training, male, aged 20 to 30 years, without any physical and eyeball lesions. Associations between intraocular pressure and Cross Choke from the guard strangling (E1, and E2 - Cross Choke from mount strangling were gotten. Intraocular pressure was determined by using Perkins tonometer, at first in the absence of physical exercise over the last 24 hours and after each strangling. Then it was carried out the intraocular pressure

  2. Gene Profiling of Aortic Valve Interstitial Cells under Elevated Pressure Conditions: Modulation of Inflammatory Gene Networks

    Directory of Open Access Journals (Sweden)

    James N. Warnock

    2011-01-01

    Full Text Available The study aimed to identify mechanosensitive pathways and gene networks that are stimulated by elevated cyclic pressure in aortic valve interstitial cells (VICs and lead to detrimental tissue remodeling and/or pathogenesis. Porcine aortic valve leaflets were exposed to cyclic pressures of 80 or 120 mmHg, corresponding to diastolic transvalvular pressure in normal and hypertensive conditions, respectively. Linear, two-cycle amplification of total RNA, followed by microarray was performed for transcriptome analysis (with qRT-PCR validation. A combination of systems biology modeling and pathway analysis identified novel genes and molecular mechanisms underlying the biological response of VICs to elevated pressure. 56 gene transcripts related to inflammatory response mechanisms were differentially expressed. TNF-α, IL-1α, and IL-1β were key cytokines identified from the gene network model. Also of interest was the discovery that pentraxin 3 (PTX3 was significantly upregulated under elevated pressure conditions (41-fold change. In conclusion, a gene network model showing differentially expressed inflammatory genes and their interactions in VICs exposed to elevated pressure has been developed. This system overview has detected key molecules that could be targeted for pharmacotherapy of aortic stenosis in hypertensive patients.

  3. Acetone photophysics at 282 nm excitation at elevated pressure and temperature. I: absorption and fluorescence experiments

    Science.gov (United States)

    Hartwig, Jason; Mittal, Gaurav; Kumar, Kamal; Sung, Chih-Jen

    2017-06-01

    This is the first in a series of two papers that presents new experimental data to extend the range of acetone photophysics to elevated pressure and temperature conditions. In this work, a flexible static and flow system is designed and characterized to study the independent as well as coupled effect of elevated pressure and temperature on acetone photophysics over pressures of 0.05‒4.0 MPa and temperatures of 295‒750 K for 282 nm excitation wavelength in nitrogen and air as bath gases. Experimental results show that at 282 nm excitation, relative fluorescence quantum yield increases with increasing pressure, decreases with increasing temperature, and that the pressure sensitivity varies weakly with elevated temperature. The previously assumed linearity of fluorescence with tracer number density is shown to only be valid over a small range. Additionally, acetone fluorescence is only moderately quenched in the presence of oxygen. The present findings yield insight into the competition between the non-radiative and collisional rates at elevated temperature and pressure, as well as provide validation datasets for an updated fluorescence model developed in the second paper.

  4. Goldmann tonometry versus the Tono-Pen XL for intraocular pressure measurement: an evaluation of the potential impact on clinical decision making in glaucoma.

    Science.gov (United States)

    Carrim, Zia I; Lavy, Tim E

    2009-11-01

    To assess the validity of the Tono-Pen XL as an alternative to the Goldmann applanation tonometer (GAT) for the measurement of intraocular pressure (IOP) in patients with ocular hypertension (OHT) and glaucoma. Over a 3 month period, patients with OHT or glaucoma attending a general clinic had IOP measurements taken using the Tono-Pen XL and the GAT. Tono-Pen measurements were taken by suitably trained nursing staff, while Goldmann tonometry was performed by the examining ophthalmologist. There were 124 eyes of 62 patients in this study. Overall, mean IOP was 18.3 +/- 4.8 mmHg using GAT and 18.8 +/- 5.5 mmHg using the Tono-Pen. Using the Bland-Altman method, the upper and lower limits of agreement between the two devices were +10.6 mmHg and -9.6 mmHg, respectively. Significant over- and under-estimates of IOP were noted in 10 (16%) patients. Our findings suggest that the Tono-Pen XL cannot be used as a substitute for GAT in the management of patients with glaucoma or OHT.

  5. [The Tono-Pen XL--a tonometer suitable for measurement of common and less common conditions associated with intraocular pressure].

    Science.gov (United States)

    Filous, A; Burdová, M; Malec, J

    1998-05-01

    In the introduction the authors describe a portable electronic tonometer Tono-pen XL and explain the principle of its function. After this follows a comparative study with Goldmann's applanation tonometry (AT) on 240 eyes in children aged 7 to 18 years. The mean value of the intraocular pressure (IOP) was 17.09 torr +/- 4.35 SD with AT and 16.46 torr +/- 4.04 SD when using the Tono-pen. Regression analysis revealed a very close correlation between the two methods of assessment (r = 0.925) with a high statistical significance (p < 0.0005). The difference as compared with AT values was constant, on average close to -0.68 torr in the whole range from 7 to 35 torr. The authors found also a significantly greater variability of values obtained by means of the Tono-pen (p = 0.0009), the mean scatter of individual values being 1.55 torr as compared with 1.25 torr in AT. However 97.1% of the eyes were within a range of 3 torr. The authors did not find a significant relationship between assessment by means of the Tono-pen and the doctor's experience. The unique advantage of Tono-pen as compared with all other methods of routine tonometry is the relatively accurate assessment of the IOP under irregular conditions of the cornea. It is also possible to take measurements in children where AT cannot be used.

  6. First-line latanoprost therapy in ocular hypertension or open-angle glaucoma patients: a 3-month efficacy analysis stratified by initial intraocular pressure

    Directory of Open Access Journals (Sweden)

    Rouland Jean

    2010-02-01

    Full Text Available Abstract Background Prospective, multicenter, randomized, double-masked trials have shown latanoprost instilled once daily to be at least as effective as and generally superior to timolol administered twice daily and to be as effective as other frequently prescribed prostaglandin analogues. This study prospectively assessed the efficacy of latanoprost monotherapy in a large cohort of treatment-naive patients with a broad range of baseline intraocular pressure (IOP levels treated in actual clinical practice settings. Methods This prospective, open-label, multicenter, uncontrolled, phase IV study included treatment-naive ocular hypertension or open-angle glaucoma subjects initiating latanoprost once daily (evening. IOP levels were measured at baseline and after 1 and 3 months. The primary efficacy outcome was mean change in IOP from baseline to month 3. Analyses were stratified by baseline IOP: ≥ 20 and vs ≥ 24 mmHg. Results Efficacy analyses (intent to treat included 572 subjects: 20 to vs -9.2 ± 3.7 mmHg, respectively; -28.0 ± 10.6% vs -34.1 ± 11.9%, respectively. An IOP reduction of ≥ 30% from baseline to month 3 was noted in 48.4% and 65.6% of subjects, respectively (p Conclusions This "real world" study found once-daily latanoprost to be effective and safe in treatment-naive ocular hypertension or open-angle glaucoma patients. Patients with baseline IOP levels of 20 to Trial Registration Trial Registration Number: NCT00647101

  7. MEASURING INTRAOCULAR PRESSURE IN WHITE'S TREE FROGS (LITORIA CAERULEA) BY REBOUND TONOMETRY: COMPARING DEVICE, TIME OF DAY, AND MANUAL VERSUS CHEMICAL RESTRAINT METHODS.

    Science.gov (United States)

    Hausmann, Jennifer C; Krisp, Ashley; Sladky, Kurt; Miller, Paul E; Mans, Christoph

    2017-06-01

    Ocular diseases reported in frogs include uveitis and glaucoma, which are associated with changes in intraocular pressure (IOP). The objectives of this study were to characterize the normal IOP for White's tree frogs ( Litoria caerulea ) using two types of rebound tonometers, and to assess whether time of day or method of restraint affected IOP. Eighteen conscious, unrestrained, ophthalmologically normal frogs were used to measure IOP using TonoVet® and TonoLab® tonometers, at three time points during the day. In a subset of 12 frogs, IOP was measured while under manual restraint using the TonoVet. Anesthesia was induced in 9 frogs using two different concentrations of MS-222 (0.5 g/L and 2 g/L) in order to evaluate for changes in IOP with the TonoVet. Mean (± SD) IOP values for the TonoLab (16.8 ± 3.9 mm Hg) were significantly higher than TonoVet values (14.7 ± 1.6 mm Hg; P frogs had significantly lower IOP (13.4 ± 1.5 mm Hg) compared with unrestrained frogs (15.3 ± 1.2 mm Hg; P frogs, but time of day and manual restraint can affect IOP values.

  8. Postoperative complications and intraocular pressure in 943 consecutive cases of 23-gauge transconjunctival pars plana vitrectomy with 1-year follow-up.

    Science.gov (United States)

    Parolini, Barbara; Prigione, Guido; Romanelli, Federica; Cereda, Matteo G; Sartore, Mauro; Pertile, Grazia

    2010-01-01

    To report the rate of postoperative complications in 943 consecutive eyes operated on with 23-gauge transconjunctival pars plana vitrectomy. Single-center, retrospective, noncomparative, interventional case series. Nine hundred and forty-three eyes underwent 23-gauge transconjunctival core and peripheral vitrectomy with peripheral laser at the sclerotomy sites from May 2005 through April 2008. The main outcome measures were intraocular pressure at 1 day and at 1 week and intra- and postoperative complications with at least 6-month follow-up. Eight hundred and thirty-one eyes (88%) did not have either significant intra- or postoperative complications. Sclerotomy leakage requiring suture occurred in 37 eyes (3.9%). One choroidal detachment (0.1%) spontaneously resolved 1 week after surgery. At postoperative Day 1, 31 eyes (3.3%) experienced transient hypotony. Forty-five eyes (4.8%) presented a subtle vitreous hemorrhage that resolved spontaneously. Two retinal detachments (0.2%) occurred, one at 1 month and one at 3 months. They resolved with one further vitrectomy. Seven hundred and forty eyes completed the 12-month follow-up and presented no further complications. Twenty-three-gauge complete vitrectomy and peripheral laser seem safe for a variety of vitreoretinal surgical procedures. The rate of post- and intraoperative complications compares favorably with 25-gauge and with the standard 20-gauge vitrectomy.

  9. Visual field protective effect of Erigeron breviscapus (vant.) Hand. Mazz. extract on glaucoma with controlled intraocular pressure: a randomized, double-blind, clinical trial.

    Science.gov (United States)

    Zhong, Yisheng; Xiang, Minhong; Ye, Wen; Cheng, Yu; Jiang, Youqin

    2010-01-01

    To evaluate the visual field protective effect of Erigeron breviscapus (vant.) Hand. Mazz. (EBHM) extract on glaucoma with controlled intraocular pressure (IOP). Forty patients (40 eyes) with primary open-angle glaucoma, visual field defects and a postsurgical IOP of <18 mmHg were enrolled. The EBHM and placebo tablets were given orally according to the randomized and double-blind principle. Two tablets (of either EBHM or placebo) were taken three times a day for a period of 6 months. Patients were examined every 2 months after treatment commenced. At the end of the study, the results were given to the drug manufacturer. All patients completed the prospective, randomized, double-blind, clinical trial. No obvious adverse effects were found in patients during the treatment period. In the placebo group, no significant difference was found in mean defect (MD) or mean sensitivity (MS) between the values at pre-treatment and after 2, 4, and 6 months of treatment. After 6 months of EBHM treatment, the MD was significantly decreased and the MS was significantly increased compared with pre-treatment (p < 0.05). In the patients with moderate and late glaucoma, the MD was significantly decreased and the MS was significantly increased after 2, 4, and 6 months of EBHM treatment compared with pre-treatment. EBHM extract may have a partial protective effect on the visual field of glaucoma patients with controlled IOP. Further studies are needed to determine the safety and effectiveness of long-term EBHM treatment.

  10. 5.2-GHz RF Power Harvester in 0.18-/spl mu/m CMOS for Implantable Intraocular Pressure Monitoring

    KAUST Repository

    Ouda, Mahmoud H.

    2013-04-17

    A first fully integrated 5.2-GHz CMOS-based RF power harvester with an on-chip antenna is presented in this paper. The design is optimized for sensors implanted inside the eye to wirelessly monitor the intraocular pressure of glaucoma patients. It includes a five-stage RF rectifier with an on-chip antenna, a dc voltage limiter, two voltage sensors, a low dropout voltage regulator, and MOSCAP based on-chip storage. The chip has been designed and fabricated in a standard 0.18-μm CMOS technology. To emulate the eye environment in measurements, a custom test setup is developed that comprises Plexiglass cavities filled with saline solution. Measurements in this setup show that the proposed chip can be charged to 1 V wirelessly from a 5-W transmitter 3 cm away from the harvester chip. The energy that is stored on the 5-nF on-chip MOSCAP when charged to 1 V is 2.5 nJ, which is sufficient to drive an arbitrary 100-μW load for 9 μs at regulated 0.8 V. Simulated efficiency of the rectifier is 42% at -7 dBm of input power.

  11. Comparison of intraocular pressure during the application of a liquid patient interface (FEMTO LDV Z8) for femtosecond laser-assisted cataract surgery using two different vacuum levels.

    Science.gov (United States)

    Ebner, Martina; Mariacher, Siegfried; Januschowski, Kai; Boden, Katrin; Seuthe, Anna-Maria; Szurman, Peter; Boden, Karl Thomas

    2017-08-01

    To evaluate intraocular pressure (IOP) using the application of a novel liquid patient interface for femtosecond laser-assisted cataract surgery with the FEMTO LDV Z8. IOP was evaluated in enucleated porcine eyes prior, during and after the application of the Femto LDV Z8 liquid patient interface (Ziemer Ophthalmic Systems, Switzerland) using intracameral cannulation (n=20), intravitreal cannulation (n=20), rebound tonometry (n=20) and indentation tonometry (n=20). Pressure was assessed prior vacuum, during vacuum (30 s, 1 min, 2 min, 3 min) and after releasing the vacuum (1 min and 2 min). Two groups with different predefined vacuum levels (350 mbar, 420 mbar) were investigated. Mean intracameral pressure (±SD) increased during vacuum application from 20 mm Hg to 52.00 mm Hg (±6.35mm Hg; p=0.005) and 45.18 mmHg (±4.34 mm Hg; p=0.005) for the 420 mbar and the 350 mbar vacuum levels, respectively. Mean intravitreal pressure increased from 20 mm Hg to 25.60 mm Hg (±9.85 mm Hg; p=0.058) and 28.10 mm Hg (±2.54 mm Hg; p=0.059) for the 420 mbar and the 350 mbar vacuum levels, respectively. Pressure values from indentation and rebound tonometry were in between intracameral and intravitreal values. Mean intracameral IOP was 18.1% higher (p=0.019) in the 420 mbar group compared with the 350 mbar group. During vacuum application of the liquid patient interface of the Femto LDV Z8 for femtosecond laser-assisted cataract surgery, IOP values were higher in the anterior chamber compared with the intravitreal pressure measurements. The higher predefined vacuum level (350 mbar vs 420 mbar) resulted in significant higher intracameral IOP. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  12. Influência da idade no comportamento da pressão intraocular em uma população da região Sul-brasileira Influence of age on intraocular pressure in a South brazilian population

    Directory of Open Access Journals (Sweden)

    Viviane Mayumi Sakata

    2010-04-01

    Full Text Available OBJETIVO: Verificar influência da idade no comportamento da pressão intraocular (PIO em população acima de 40 anos. MÉTODOS: Neste estudo observacional transversal realizado no município de Piraquara - PR, a PIO foi aferida através da tonometria de Goldmann. Todos os indivíduos foram submetidos a exame de triagem, sendo os suspeitos de glaucoma ou hipertensão ocular encaminhados ao atendimento de retorno para realização de exame oftalmológico completo. Para fins de análise estatística, os pacientes foram divididos em grupos etários (40-49; 50-59; 60-69 e acima de 70 anos. Posteriormente todos os pacientes portadores de glaucoma ou suspeita, hipertensão arterial sistêmica (HAS ou Diabetes mellitus (DM foram excluídos. RESULTADOS: Avaliaram-se 3360 indivíduos com média de idade de 54,04 ± 10,52 anos, sendo 59,79% do sexo feminino. Não se observou diferença estatisticamente significativa entre a média da PIO nos diferentes grupos etários (p=0,19; teste ANOVA. Da mesma forma, não foi observada correlação significativa entre a PIO e a idade (p = 0,11; correlação linear de Pearson. Após exclusão dos indivíduos portadores de HAS (1671, DM (n=360, glaucoma ou suspeita de glaucoma (n=161 não se observou diferença estatisticamente significativa entre a média da PIO e a idade (p=0,17; teste ANOVA. No entanto, uma fraca correlação negativa, porém significativa, foi encontrada entre PIO e idade (p=0,03; R=-0,055, correlação linear Pearson. CONCLUSÃO: Na presente amostra, não foi observada influência significativa da idade na PIO, entretanto, após a exclusão de indivíduos com glaucoma, HAS e DM, observou-se uma fraca correlação linear negativa e significativa entre as duas variáveis.PURPOSE: To assess the influence of age on intra-ocular pressure (IOP in subjects aged over 40 years old. METHODS: This transversal and observational study realized at Piraquara city (PR measured the IOP using Goldmann applanation

  13. Analysis and evaluation system for elevated temperature design of pressure vessels

    International Nuclear Information System (INIS)

    Hayakawa, Teiji; Sayawaki, Masaaki; Nishitani, Masahiro; Mii, Tatsuo; Murasawa, Kanji

    1977-01-01

    In pressure vessel technology, intensive efforts have recently been made to develop the elevated temperature design methods. Much of the impetus of these efforts has been provided mainly by the results of the Liquid Metal Fast Breeder Reactor (LMFBR) and more recently, of the High Temperature Gas-cooled Reactor (HTGR) Programs. The pressure vessels and associated components in these new type nuclear power plants must operate for long periods at elevated temperature where creep effects are significant and then must be designed by rigorous analysis for high reliability and safety. To carry out such an elevated temperature designing, numbers of highly developed analysis and evaluation techniques, which are so complicated as to be impossible by manual work, are indispensable. Under these circumstances, the authors have made the following approaches in the study: (1) Study into basic concepts and the associated techniques in elevated temperature design. (2) Systematization (Analysis System) of the procedure for loads and stress analyses. (3) Development of post-processor, ''POST-1592'', for strength evaluation based on ASME Code Case 1592-7. By linking the POST-1592 together with the Analysis System, an analysis and evaluation system is developed for an elevated temperature design of pressure vessels. Consequently, designing of elevated temperature vessels by detailed analysis and evaluation has easily and effectively become feasible by applying this software system. (auth.)

  14. Biocompatibility of Intraocular Lenses.

    Science.gov (United States)

    Özyol, Pelin; Özyol, Erhan; Karel, Fatih

    2017-08-01

    The performance of an intraocular lens is determined by several factors such as the surgical technique, surgical complications, intraocular lens biomaterial and design, and host reaction to the lens. The factor indicating the biocompatibility of an intraocular lens is the behavior of inflammatory and lens epithelial cells. Hence, the biocompatibility of intraocular lens materials is assessed in terms of uveal biocompatibility, based on the inflammatory foreign-body reaction of the eye against the implant, and in terms of capsular biocompatibility, determined by the relationship of the intraocular lens with residual lens epithelial cells within the capsular bag. Insufficient biocompatibility of intraocular lens materials may result in different clinical entities such as anterior capsule opacification, posterior capsule opacification, and lens epithelial cell ongrowth. Intraocular lenses are increasingly implanted much earlier in life in cases such as refractive lens exchange or pediatric intraocular lens implantation after congenital cataract surgery, and these lenses are expected to exhibit maximum performance for many decades. The materials used in intraocular lens manufacture should, therefore, ensure long-term uveal and capsular biocompatibility. In this article, we review the currently available materials used in the manufacture of intraocular lenses, especially with regard to their uveal and capsular biocompatibility, and discuss efforts to improve the biocompatibility of intraocular lenses.

  15. Time-resolved stereoscopic PIV study of flashback in swirl flames at elevated pressures

    Science.gov (United States)

    Ranjan, Rakesh; Ebi, Dominik; Clemens, Noel

    2015-11-01

    Boundary layer flashback of turbulent premixed swirl flames can pose a major challenge to the operation of stationary gas turbines, especially with hydrogen-rich fuels. To improve our understanding of the physics behind this phenomenon at gas turbine relevant conditions, it is essential to investigate flashback at elevated pressures. With this purpose in mind, flashback experiments with hydrogen/methane-air premixtures are conducted in a model swirl combustor installed in an optically accessible high-pressure combustion facility. We have employed stereoscopic PIV in conjunction with high speed chemiluminiscence imaging to study the upstream propagation of the flame in the premix tube during flashback. Experiments are run at pressures ranging from 1 atm to 5 atm. These time-resolved measurements provide valuable insight into the flame-flow interaction during flashback at elevated pressures.

  16. Clinical significance of elevated intraabdominal pressure during common conditions and procedures.

    Science.gov (United States)

    Larsson, A

    2007-01-01

    Pregnancy, obesity, peritoneal dialysis, pneumoperitoneum, prone position and application of positive end-expiratory pressure are associated with elevated intraabdominal pressure (IAP). To review the relation between these conditions and procedures, and intraabdominal hypertension (IAH) or abdominal compartment syndrome (ACS). Search of PubMed and Google Scholar and review of article bibliographies. Only obesity, peritoneal dialysis, and pneumoperitoneum are associated with symptoms related to IAH and these symptoms are reversible.

  17. Implantation of a novel telemetric intraocular pressure sensor in patients with glaucoma (ARGOS study): 1-year results.

    Science.gov (United States)

    Koutsonas, Antonis; Walter, Peter; Roessler, Gernot; Plange, Niklas

    2015-01-22

    We investigated the safety of a telemetric IOP sensor and the accuracy of its IOP measurements in six patients with open-angle glaucoma and cataract. The study design was a prospective, single-center clinical trial. Here we present 1-year follow-up data. A ring-shaped telemetric IOP sensor was implanted in the ciliary sulcus after implantation of the intracapsular lens, during planned cataract surgery. The sensor is encapsulated in silicone rubber and consists of a miniature device with eight pressure-sensitive capacitors and a circular microcoil antenna. IOP measurements are performed with a reader unit held in front of the eye. IOP is calculated as the differences between the absolute pressure inside the eye (pressure sensor) and that outside the eye (reader unit). The sensor was successfully implanted in all patients. Four patients developed sterile anterior chamber inflammation that resolved completely within 9 days after surgery with anti-inflammatory treatment. All patients showed mild to moderate pupillary distortion and pigment dispersion after surgery. Telemetric IOP measurement was performed in all patients at all visits, and the patients successfully performed self-tonometry at home after receiving instructions. Telemetric IOP values showed similar profiles compared to those of Goldmann applanation tonometry (GAT). Three patients showed a relevant IOP step during follow-up, and in one patient, negative values were obtained throughout the study. Despite early postoperative anterior chamber inflammation, the IOP sensor was well tolerated by all patients. We describe the first prospective clinical study of a noncontact IOP sensor that potentially enables continuous IOP monitoring in patients with glaucoma. The sensor shape and size needs to be adapted to avoid pupillary distortion and to confirm that IOP measurements are accurately recorded in comparison to those of GAT. ( www.germanctr.de; number DRKS00003335.). Copyright 2015 The Association for Research

  18. Acetone photophysics at 282 nm excitation at elevated pressure and temperature. II: Fluorescence modeling

    Science.gov (United States)

    Hartwig, Jason; Raju, Mandhapati; Sung, Chih-Jen

    2017-07-01

    This is the second in a series of two papers that presents an updated fluorescence model and compares with the new experimental data reported in the first paper, as well as the available literature data, to extend the range of acetone photophysics to elevated pressure and temperature conditions. This work elucidates the complete acetone photophysical model in terms of each and every competing radiative and non-radiative rate. The acetone fluorescence model is then thoroughly examined and optimized based on disparity with recently conducted elevated pressure and temperature photophysical calibration experiments. The current work offers insight into the competition between non-radiative and vibrational energy decay rates at elevated temperature and pressure and proposes a global optimization of model parameters from the photophysical model developed by Thurber (Acetone Laser-Induced Fluorescence for Temperature and Multiparameter Imaging in Gaseous Flows. PhD thesis, Stanford University Mechanical Engineering Department, 1999). The collisional constants of proportionality, which govern vibrational relaxation, are shown to be temperature dependent at elevated pressures. A new oxygen quenching rate is proposed which takes into account collisions with oxygen as well as the oxygen-assisted intersystem crossing component. Additionally, global trends in ketone photophysics are presented and discussed.

  19. Elevated plantar pressures in neuropathic diabetic patients with claw/hammer toe deformity

    NARCIS (Netherlands)

    Dr Sicco Bus; Dr Marcel Levi; Dr Robert P.J. Michels; Dr. ir. A. de Lange; Dr Mario Maas

    2005-01-01

    Elevated plantar foot pressures during gait in diabetic patients with neuropathy have been suggested to result, among other factors, from the distal displacement of sub-metatarsal head (MTH) fat-pad cushions caused by to claw/hammer toe deformity. The purpose of this study was to quantitatively

  20. Effect of renal venous pressure elevation on tubular sodium and water reabsorption in the dog kidney

    DEFF Research Database (Denmark)

    Abildgaard, U; Amtorp, O; Holstein-Rathlou, N H

    1988-01-01

    This study was performed in order to quantify the effects of renal venous pressure (RVP) elevation on absolute and fractional reabsorption rates of sodium and water in proximal and distal segments of the nephron in dog kidneys. Renal blood flow (RBF) was measured electromagnetically. Clearance...

  1. Effects of elevated CO2 partial pressure and temperature on the coccolithophore Syracosphaera pulchra

    NARCIS (Netherlands)

    Fiorini, S.; Middelburg, J.J.; Gattuso, J.P.

    2011-01-01

    The effects of elevated partial pressure of CO2 (pCO2) and temperature on the cocco - lithophore Syracosphaera pulchra were investigated in isolation and in combination. Both the diploid and the haploid life stages were studied. Batch cultures were grown under 4 conditions: 400 μatm and 19°C; 400

  2. Evaluation of Optical Coherence Tomography to Detect Elevated Intracranial Pressure in Children.

    Science.gov (United States)

    Swanson, Jordan W; Aleman, Tomas S; Xu, Wen; Ying, Gui-Shuang; Pan, Wei; Liu, Grant T; Lang, Shih-Shan; Heuer, Gregory G; Storm, Phillip B; Bartlett, Scott P; Katowitz, William R; Taylor, Jesse A

    2017-04-01

    Detecting elevated intracranial pressure in children with subacute conditions, such as craniosynostosis or tumor, may enable timely intervention and prevent neurocognitive impairment, but conventional techniques are invasive and often equivocal. Elevated intracranial pressure leads to structural changes in the peripapillary retina. Spectral-domain (SD) optical coherence tomography (OCT) can noninvasively quantify retinal layers to a micron-level resolution. To evaluate whether retinal measurements from OCT can serve as an effective surrogate for invasive intracranial pressure measurement. This cross-sectional study included patients undergoing procedures at the Children's Hospital of Philadelphia from September 2014 to June 2015. Three groups of patients (n = 79) were prospectively enrolled from the Craniofacial Surgery clinic including patients with craniosynostosis (n = 40). The positive control cohort consisted of patients with hydrocephalus and suspected intracranial hypertension (n = 5), and the negative control cohort consisted of otherwise healthy patients undergoing a minor procedure (n = 34). Spectral-domain OCT was performed preoperatively in all cohorts. Children with cranial pathology, but not negative control patients, underwent direct intraoperative intracranial pressure measurement. The primary outcome was the association between peripapillary retinal OCT parameters and directly measured elevated intracranial pressure. The mean (SD) age was 34.6 (45.2) months in the craniosynostosis cohort (33% female), 48.9 (83.8) months in the hydrocephalus and suspected intracranial hypertension cohort (60% female), and 59.7 (64.4) months in the healthy cohort (47% female). Intracranial pressure correlated with maximal retinal nerve fiber layer thickness (r = 0.60, P ≤ .001), maximal retinal thickness (r = 0.53, P ≤ .001), and maximal anterior retinal projection (r = 0.53, P = .003). Using cut points derived from the

  3. Effects of preservative-free tafluprost on tear film osmolarity, tolerability, and intraocular pressure in previously treated patients with open-angle glaucoma

    Directory of Open Access Journals (Sweden)

    Janulevičienė I

    2012-01-01

    Full Text Available Ingrida Januleviciene, Irmante Derkac, Lina Grybauskiene, Ruta Paulauskaite, Ruta Gromnickaite, Loreta KuzmieneEye Clinic of Kaunas Medical Academy of Lithuanian University of Health Sciences, Kaunas, LithuaniaPurpose: To compare the effects on tolerability, tear osmolarity, and intraocular pressure (IOP-lowering effect of switching from benzalkonium chloride (BAK containing prostaglandin analog (PGA latanoprost to preservative-free tafluprost.Patients and methods: Thirty patients with open-angle glaucoma (N = 60 eyes, 26 women (87% and four men (13% aged 64.1 (SD 14.1 years, showing abnormal values of tear osmolarity, corneal fluorescein staining, tear film break-up time (TBUT, or subjective discomfort with current latanoprost treatment were included. After tear osmolarity (TearLab™ Osmolarity System, TBUT, corneal fluorescein staining, and baseline IOP (Goldmann tonometer measurements and the completion of Ocular Surface Disease Index and Ocular Surface Symptoms in Glaucoma Scale questionnaires, patients were assigned to preservative-free tafluprost treatment. Measurements were repeated 2, 6 and 12 weeks after change of medication.Results: No statistically significant differences in IOP were observed 2, 6, and 12 weeks after switching to preservative-free tafluprost. Mean IOP at baseline was 16.4 mmHg (SD 2.9, after 2 weeks 16.2 mmHg (2.8, after 6 weeks 16.2 (2.6, and after 12 weeks 16.3 mmHg (2.3. Mean tear osmolarity decreased significantly from 315.7 mOsm/L (SD 15.1 at baseline to 308.0 ± 14.4 mOsm/L (P = 0.002, 301.7 ± 14.5 mOsm/L (P < 0.001, and 302.0 ± 9.9 mOsm/L (P < 0.001 2, 6, and 12 weeks after changing medication to preservative-free tafluprost, respectively. Tear osmolarity was lower in 37 eyes (61.7% after 2 weeks, in 46 eyes (76.7% after 6 weeks, and in 49 eyes (81.7% after 12 weeks (P < 0.005; t-test. At baseline corneal fluorescein staining was observed in 43 eyes (71.7%, after 2 weeks in 34 eyes (56.7%, after 6 weeks

  4. Central corneal thickness, intraocular pressure, and degree of myopia in an adult myopic population aged 20 to 40 years in southeast Spain: determination and relationships

    Directory of Open Access Journals (Sweden)

    Manuel Garcia-Medina

    2011-02-01

    Full Text Available Manuel Garcia-Medina1, Jose Javier Garcia-Medina2,3, Pablo Garrido-Fernandez1, Jose Galvan-Espinosa1, Jesus Martin-Molina1, Carlos Garcia-Maturana4, Sergio Perez-Pardo1, Maria Dolores Pinazo-Duran3 1Department of Ophthalmology, Torrecardenas Hospital, Almeria, Spain; 2Department of Ophthalmology, Huercal Overa Hospital, Almeria, Spain; 3Ophthalmology Research Unit “Santiago Grisolia”, University Hospital Doctor Peset, Valencia, Spain; 4University of Sevilla, SpainObjective: To determine the values of, and study the relationships among, central corneal thickness (CCT, intraocular pressure (IOP, and degree of myopia (DM in an adult myopic population aged 20 to 40 years in Almeria (southeast Spain. To our knowledge this is first study of this kind in this region.Methods: An observational, descriptive, cross-sectional study was done in which a sample of 310 myopic patients (620 eyes aged 20 to 40 years was selected by gender- and age-stratified sampling, which was proportionally fixed to the size of the population strata for which a 20% prevalence of myopia, 5% epsilon, and a 95% confidence interval were hypothesized. We studied IOP, CCT, and DM and their relationships by calculating the mean, standard deviation, 95% confidence interval for the mean, median, Fisher’s asymmetry coefficient, range (maximum, minimum, and the Brown-Forsythe’s robust test for each variable (IOP, CCT, and DM.Results: In the adult myopic population of Almeria aged 20 to 40 years (mean of 29.8, the mean overall CCT was 550.12 µm. The corneas of men were thicker than those of women (P = 0.014. CCT was stable as no significant differences were seen in the 20- to 40-year-old subjects’ CCT values. The mean overall IOP was 13.60 mmHg. Men had a higher IOP than women (P = 0.002. Subjects over 30 years (13.83 had a higher IOP than those under 30 (13.38 (P = 0.04. The mean overall DM was -4.18 diopters. Men had less myopia than women (P < 0.001. Myopia was stable in the

  5. Cartilage contact pressure elevations in dysplastic hips: a chronic overload model

    Directory of Open Access Journals (Sweden)

    Grosland Nicole M

    2006-10-01

    Full Text Available Abstract Background Developmental dysplasia of the hip (DDH is a condition in which bone growth irregularities subject articular cartilage to higher mechanical stresses, increase susceptibility to subluxation, and elevate the risk of early osteoarthritis. Study objectives were to calculate three-dimensional cartilage contact stresses and to examine increases of accumulated pressure exposure over a gait cycle that may initiate the osteoarthritic process in the human hip, in the absence of trauma or surgical intervention. Methods Patient-specific, non-linear, contact finite element models, constructed from computed tomography arthrograms using a custom-built meshing program, were subjected to normal gait cycle loads. Results Peak contact pressures for dysplastic and asymptomatic hips ranged from 3.56 – 9.88 MPa. Spatially discriminatory cumulative contact pressures ranged from 2.45 – 6.62 MPa per gait cycle. Chronic over-pressure doses, for 2 million cycles per year over 20 years, ranged from 0.463 – 5.85 MPa-years using a 2-MPa damage threshold. Conclusion There were significant differences between the normal control and the asymptomatic hips, and a trend towards significance between the asymptomatic and symptomatic hips of patients afflicted with developmental dysplasia of the hip. The magnitudes of peak cumulative contact pressure differed between apposed articular surfaces. Bone irregularities caused localized pressure elevations and an upward trend between chronic over-pressure exposure and increasing Severin classification.

  6. Repeatability of intraocular pressure measurements with Icare PRO rebound, Tono-Pen AVIA, and Goldmann tonometers in sitting and reclining positions.

    Science.gov (United States)

    Schweier, Caterina; Hanson, James V M; Funk, Jens; Töteberg-Harms, Marc

    2013-09-05

    Icare PRO (ICP) is a new Rebound tonometer that is able to measure intraocular pressure (IOP) in both sitting and reclining positions. In this study, the gold standard Goldmann tonometer (GAT) was compared to ICP and Tono-Pen AVIA (TPA). Hypothesis was that repeatability of GAT is superior to ICP and TPA. 36 eyes of 36 healthy caucasian individuals, 13 male and 26 females, 17 right and 19 left eyes have been included in this prospective, randomized, cross-sectional study. The study was conducted at a single site (Dept. of Ophthalmology, University Hospital Zurich, Switzerland). Primary outcome measures were Intraclass correlation coefficients (ICC) and coefficients of variation (COV) and test-retest repeatability as visualized by Bland-Altman analysis. Secondary outcome measures were IOP in sitting (GAT, ICP and TPA) and in reclining (ICP and TPA) position. Mean IOP measured by GAT was 14.9 ± 3.5 mmHg. Mean IOP measured by ICP was 15.6 ± 3.1 mmHg (with TPA 14.8 ± 2.7 mmHg) in sitting and 16.5 ± 3.5 mmHg (with TPA 17.0 ± 3.0 mmHg) in reclining positions. COVs ranged from 2.9% (GAT) to 6.9% (ICP reclining) and ICCs from 0.819 (ICP reclining) to 0.972 (GAT). Repeatability is good with all three devices. GAT has higher repeatability compared to the two tested hand-held devices with lowest COVs and highest ICCs. IOP was higher in the reclining compared to the sitting position. The study was registered to the Clinical Trials Register of the US National Institute of Health, NCT01325324.

  7. Effect of mild to moderate myopic correction by laser-assisted in situ keratomileusis on intraocular pressure measurements with goldmann applanation tonometer, tono-pen, and pneumatonometer.

    Science.gov (United States)

    Vakili, Roya; Choudhri, Saira A; Tauber, Shachar; Shields, M Bruce

    2002-12-01

    To evaluate the effect of mild to moderate myopic correction by laser-assisted in situ keratomileusis (LASIK) on intraocular pressure (IOP) measurements with three tonometers: the Goldmann applanation tonometer, Tono-Pen, and pneumatonometer. In a prospective study of a clinic-based population undergoing elective LASIK surgery for myopia correction, IOP measurements were obtained preoperatively and postoperatively with a Goldmann applanation tonometer, Tono-Pen, and pneumatonometer. Central corneal thickness and keratometric and astigmatism measurements were also obtained before and after surgery. A paired test was used to evaluate the significance of differences between preoperative and postoperative IOP measurements with each instrument. Linear regression was used to correlate IOP measurements with degree of myopia corrected, astigmatism, and central corneal thickness before and after surgery. The study included 66 eyes of 34 individuals with a mean preoperative refractive error of -5.66 + 2.3 D (mean + SD). The reduction of central corneal thickness after LASIK of 0.032 + 0.030 mm (mean + SD) was statistically significant ( < 0.0001). However, there was no statistically significant change in mean IOP after the procedure with the Goldmann applanation tonometer or the Tono-Pen, while the pneumatonometer, was associated with a small but statistically significant decrease in mean IOP of 1.1 mm Hg. In this group of patients with mild to moderate myopia, LASIK had little or no statistically significant influence on IOP readings obtained with a Goldmann applanation tonometer, Tono-Pen, or pneumatonometer. This finding is in contrast to earlier reports of greater amounts of myopic correction, in which significant reductions in measured IOP were observed. Further study is needed to determine whether a critical amount of corneal change after LASIK is required to have a significant effect on IOP measurements.

  8. The influence of central corneal thickness and age on intraocular pressure measured by pneumotonometry, non-contact tonometry, the Tono-Pen XL, and Goldmann applanation tonometry.

    Science.gov (United States)

    Tonnu, P-A; Ho, T; Newson, T; El Sheikh, A; Sharma, K; White, E; Bunce, C; Garway-Heath, D

    2005-07-01

    To evaluate the influence of central corneal thickness (CCT) on intraocular pressure (IOP) measurements made with the Goldmann applanation tonometer (GAT), Tono-Pen XL, ocular blood flow tonograph (OBF), and Canon TX-10 non-contact tonometer (NCT). CCT was recorded for either eye (randomly selected) of each of 105 untreated patients with ocular hypertension and glaucoma attending the glaucoma research unit at Moorfields Eye Hospital. For each of the selected eyes, IOP was measured with the GAT (two observers), Tono-Pen, OBF, and NCT in a randomised order. The relation of measured IOP and of inter-tonometer differences with CCT and subject age was explored by linear regression analysis. A significant association between measured IOP and CCT was found with each instrument. The change in measured IOP for a 10 mum increase in CCT was 0.28, 0.31, 0.38, and 0.46 for the GAT, Tono-Pen, OBF, and NCT, respectively (all p< or = 0.05). There was a significant association between the NCT/GAT differences and CCT, with a tendency of NCT to overestimate GAT in eyes with thicker corneas. There was a significant association between GAT/Tono-Pen and OBF/Tono-Pen differences and age, with a tendency of GAT and OBF to overestimate the Tono-Pen in eyes of older subjects. IOP measurement by all four methods is affected by CCT. The NCT is affected by CCT significantly more than the GAT. Subject age has a differential effect on the IOP measurements made by the GAT and OBF compared to the Tono-Pen.

  9. Effect of central corneal thickness and radius of the corneal curvature on intraocular pressure measured with the Tono-Pen and noncontact tonometer in healthy schoolchildren.

    Science.gov (United States)

    Yildirim, Nilgun; Sahin, Afsun; Basmak, Hikmet; Bal, Cengiz

    2007-01-01

    To determine the effect of central corneal thickness and radius of the corneal curvature on intraocular pressure (IOP) measurements using the Tono-Pen and a noncontact tonometer in healthy Turkish schoolchildren. IOP was measured with the Tono-Pen and a noncontact tonometer in 602 eyes of 602 healthy schoolchildren with a mean age of 10.1 +/- 1.6 years. Central corneal thickness was measured using an ultrasonic pachymeter after all IOP determinations had been made. The effect of central corneal thickness, radius of the corneal curvature, and sex on measured IOP was explored by linear regression analysis. The mean central corneal thickness was found to be 564.92 +/- 32 microm. The mean IOP readings were 17.9 +/- 2 mm Hg using the Tono-Pen, and 16.7 +/- 2 mm Hg using a noncontact tonometer. The Tono-Pen measured IOP values slightly greater than the noncontact tonometer (P < .0001). A significant association between measured IOP and central corneal thickness was found with each device. The IOP increased 2.1 and 4.2 mm Hg with every 100-microm increase in central corneal thickness for the Tono-Pen and the noncontact tonometer, respectively. The dependence of IOP on central corneal thickness did not differ between boys and girls. There was a significant association between the Tono-Pen and noncontact tonometer differences and central corneal thickness; the noncontact tonometer tended to overestimate IOP in eyes with thicker corneas. The Tono-Pen readings appeared to be less affected by corneal thickness than those of the noncontact tonometer. The corneal radius of curvature had no significant effect on measured IOP with each device. Because the Tono-Pen was relatively easy to use and less affected by corneal thickness, it may be an alternative method for measuring IOP in children.

  10. Comparison of Intraocular Pressure Measurements between Icare Pro Rebound Tonometer and Tono-Pen XL Tonometer in Supine and Lateral Decubitus Body Positions.

    Science.gov (United States)

    Lee, Tae-Eun; Yoo, Chungkwon; Hwang, Jin-Young; Lin, Shan; Kim, Yong Yeon

    2015-09-01

    To compare intraocular pressure (IOP) measurements obtained using the Icare Pro rebound tonometer and Tono-Pen XL tonometer in supine and lateral decubitus body positions. One-hundred eyes of 50 subjects (normal volunteers or glaucoma suspects) were enrolled in this prospective observational study. IOP was measured in both eyes using the Icare Pro and Tono-Pen XL in the sitting position and the recumbent positions including supine, right lateral decubitus and left lateral decubitus. IOP was measured five minutes after assuming each of the recumbent postures in a randomized sequence. The eye on the lower side in the lateral decubitus position was termed as the dependent eye. Agreement of IOP readings between the Icare Pro and Tono-Pen was assessed in all recumbent positions. Differences of IOP readings (ΔIOP) between the two tonometers and their correlations with ocular parameters were also assessed in all positions. The IOP readings obtained using Icare Pro and Tono-Pen showed good correlations in supine and lateral decubitus positions (all r > 0.7, p < 0.005), although Icare Pro readings were higher than Tono-Pen readings (all p < 0.001) in all positions. The ΔIOP showed a weakly positive correlation with central corneal thickness in both eyes, whereas such a positive correlation was found only in the dependent eye in the lateral decubitus positions (r = 0.307-0.531, all p < 0.005). Both the spherical equivalents and axial lengths were not correlated with ΔIOP in all positions. IOP readings obtained with Tono-Pen and Icare Pro tonometers showed good agreement in supine as well as in lateral decubitus positions, although Icare readings were higher than Tono-Pen readings in all positions. Such differences in IOP readings between the different tonometers need to be considered when measuring IOPs in various body positions.

  11. Repeatability and Reproducibility of Measurements Using a NT-530P Noncontact Tono/Pachymeter and Correlation of Central Corneal Thickness with Intraocular Pressure

    Directory of Open Access Journals (Sweden)

    Fusako Fujimura

    2013-01-01

    Full Text Available Purpose. To investigate the repeatability and reproducibility of intraocular pressure (IOP and central corneal thickness (CCT measurements using a noncontact tono/pachymeter (NT-530P and to assess the correlation of CCT with IOP. Methods. Forty-six eyes of healthy volunteers were measured by two examiners. Three consecutive measurements per eye were performed. Repeatability was assessed using the coefficient of variation, and reproducibility was assessed using Bland-Altman plots. Linear correlations were used to determine agreement between CCT and noncorrected IOP and CCT and corrected IOP, which was calculated using a formula built into the NT-530P. Results. The coefficient of variation for IOP was 6.4% and for CCT was 0.4%. The 95% limits of agreement between examiners were −0.17±1.42 mmHg (range: −2.95 to 2.61 mmHg for IOP, −0.93±4.37 μm (range: −9.50 to 7.64 μm for CCT. The corrected IOP was significantly higher than the noncorrected IOP (P=0.010.3. The noncorrected IOP significantly correlated with CCT (r=−0.4883, P=0.0006. The corrected IOP showed no significant correlation with CCT (r=−0.0285, P=0.8509. Conclusions. NT-530P offered repeatability and reproducibility in both IOP and CCT measurements. The corrected IOP calculated using the NT-530P was independent of the CCT, suggesting that this IOP may be less influenced by the central corneal thickness.

  12. Repeatability and reproducibility of measurements using a NT-530P noncontact tono/pachymeter and correlation of central corneal thickness with intraocular pressure.

    Science.gov (United States)

    Fujimura, Fusako; Kamiya, Kazutaka; Fujiwara, Kazuko; Shoji, Nobuyuki; Shimizu, Kimiya

    2013-01-01

    To investigate the repeatability and reproducibility of intraocular pressure (IOP) and central corneal thickness (CCT) measurements using a noncontact tono/pachymeter (NT-530P) and to assess the correlation of CCT with IOP. Forty-six eyes of healthy volunteers were measured by two examiners. Three consecutive measurements per eye were performed. Repeatability was assessed using the coefficient of variation, and reproducibility was assessed using Bland-Altman plots. Linear correlations were used to determine agreement between CCT and noncorrected IOP and CCT and corrected IOP, which was calculated using a formula built into the NT-530P. The coefficient of variation for IOP was 6.4% and for CCT was 0.4%. The 95% limits of agreement between examiners were -0.17 ± 1.42 mmHg (range: -2.95 to 2.61 mmHg) for IOP, -0.93 ± 4.37  μ m (range: -9.50 to 7.64  μm) for CCT. The corrected IOP was significantly higher than the noncorrected IOP (P = 0.010.3). The noncorrected IOP significantly correlated with CCT (r = -0.4883, P = 0.0006). The corrected IOP showed no significant correlation with CCT (r = -0.0285, P = 0.8509). NT-530P offered repeatability and reproducibility in both IOP and CCT measurements. The corrected IOP calculated using the NT-530P was independent of the CCT, suggesting that this IOP may be less influenced by the central corneal thickness.

  13. Effect of instrument orientation on the accuracy of intraocular pressure measurements in human cadaveric eyes: manometric evaluation of the model 30 classic Pneumatonometer and Tono-Pen XL.

    Science.gov (United States)

    Currie, Benjamin D; Bagga, Harmohina; Rademaker, Alfred W; Tanna, Angelo P

    2011-10-01

    To determine the effects of probe orientation on the accuracy of intraocular pressure (IOP) measurements obtained with pneumatonometry (Model 30 Classic Pneumatonometer, Reichert Ophthalmic Instruments, Depew, NY) and with a handheld electronic tonometer (Tono-Pen XL, Reichert Ophthalmic Instruments, Depew, NY). Six enucleated human eyes were obtained fewer than 24 hours postmortem. IOP was maintained at 10, 20, and 30 mm Hg, sequentially, via liquid column manometry. At each IOP setpoint, the eyes were positioned to mimic a sitting, supine, and prone patient. Pneumatonometry was performed in the sitting and supine orientations. Tono-Pen measurements were performed in the sitting, supine, and prone orientations. Accuracy was analyzed using multifactor repeated measures analysis of variance, and one-sample t tests. At all IOP setpoints, for both instruments, probe orientation had no significant effect on the IOP measurement (pneumatonometer P=0.58; Tono-Pen P=0.85). At all 3 setpoints (10, 20, and 30 mm Hg) the pneumatonometer overestimated IOP (P<0.0001; P<0.0001; P=0.005, respectively). The Tono-Pen overestimated IOP at the 10 mm Hg setpoint (P<0.0001), but underestimated IOP at the 20 and 30 mm Hg setpoints (P=0.03; P<0.0001, respectively). Under experimental conditions, probe orientation had no significant effect on IOP measurements for either instrument, suggesting that both can be used without correction in the tested orientations. In enucleated human cadaveric eyes, the pneumatonometer overestimated IOP at all setpoints. The handheld electronic tonometer overestimated IOP at 10 mm Hg, but underestimated IOP at the higher setpoints. It is unknown if these findings are generalizable to human eyes in vivo.

  14. [Measurement of intraocular pressure using the Tono-Pen in comparison with Goldmann applanation tonometry - a clinical study in 100 eyes].

    Science.gov (United States)

    Deuter, Christoph M E; Schlote, Torsten; Hahn, Gesa A; Bende, Thomas; Derse, Matthias

    2002-03-01

    In clinical practice ophthalmologists often need a tonometer which is independent of a slit lamp. Such a hand-held device is the Tono-Pen. We compared the precision of two equal Tono-Pens with Goldmann applanation tonometry. Measurement of intraocular pressure (IOP) was done in 100 eyes of 51 patients (mean age 63 +/- 15 years) suffering from ocular hypertension or glaucoma. According to a random table either the right or left eye was measured using Goldmann tonometer first and the Tono-Pen second. For the other eye the measurement was reversed. One of the two equal Tono-Pens (Solan/USA) was used according to a second random table. Three measurements were obtained with each instrument on both eyes within 15 minutes subsequently. Patients were placed in an upright position for all measurements. Even for well-trained ophthalmologists a learning curve of approximately 10 measurements was observed using the Tono-Pen. The Tono-Pen measured an average IOP of 16.9 mm Hg in all 100 eyes. The Goldmann tonometer measured an average IOP of 17.7 mm Hg. The difference was not statistically significant. The standard deviation for all measurements was better for the Tono-Pen (4.7 mm Hg vs 5.8 mm Hg for Goldmann tonometer). No reduction of the IOP after Tono-Pen measurement was observed (in contrast to the Goldmann tonometer). The reproducibility of the Tono-Pen on the same eye was inferior to the Goldmann tonometer by a factor of 2. There was an almost significant difference in reproducibility between two equal Tono-Pens. Measurement of IOP with the Tono-Pen is comparable to Goldmann applanation tonometry if an average of 3 measurements is used. The difference between two equal Tono-Pens indicates the need for improvement of the quality check during production.

  15. Agreement between diurnal variations of intraocular pressure by Tono-Pen and Goldmann applanation tonometer in patients on topical anti-glaucoma medication.

    Science.gov (United States)

    Gupta, Shikha; Sinha, Gautam; Sharma, Reetika; Nayak, Bhagabat; Patil, Bharat; Kashyap, Bibhuti; Shameer, Abdul; Dada, Tanuj

    2016-02-01

    To estimate agreement in diurnal variations of intraocular pressure (IOP) by Tono-Pen (TP) and Goldmann applanation tonometer (GAT) in glaucoma patients on topical anti-glaucoma medication(s). IOP was measured at every 3 h from 7 a.m. to 10 a.m. in 50 eyes of glaucoma patients on topical medication(s). Diurnal fluctuation of IOP by each method was calculated as maximum-minimum IOP in a day. Central corneal thickness (CCT) was measured by ultrasonic pachymeter. There was good correlation between TP and GAT at all times during a day, minimum, and maximum IOPs during a day (Correlation coefficient, 0.706 at 7 a.m., 0.624 at 10 a.m., 0.682 at 1 p.m., 0.814 at 4 p.m., 0.652 at 7 p.m., 0.572 at 10 p.m., 0.668 minimum IOP, 0.689 maximum IOP). Mean IOPs by TP were always higher than GAT at all times during a day. Bland-Altman plots suggested a close relationship between the two sets of readings, and that this relationship was consistent at different times in a day, in maximum IOPs, minimum IOPs and also in fluctuation of IOPs. Linear regression analysis between the differences of diurnal fluctuation (diurnal fluctuation by GAT-diurnal fluctuation by TP) and CCT showed strong association (R 2 = 0.857, p < 0.001). The mean change in difference of diurnal fluctuation (GAT-TP) for a 10-micron increase in CCT was 0.69 mmHg. TP can be considered a reliable alternative to GAT in glaucoma patients for knowing the diurnal control of IOP; however these two methods should not be used interchangeably. Difference of diurnal fluctuation between two methods is dependent on CCT.

  16. Numerical analysis of specific absorption rate in the human head due to a 13.56 MHz RFID-based intra-ocular pressure measurement system

    International Nuclear Information System (INIS)

    Hirtl, Rene; Schmid, Gernot

    2013-01-01

    A modern wireless intra-ocular pressure monitoring system, based on 13.56 MHz inductively coupled data transmission, was dosimetrically analyzed with respect to the specific absorption rate (SAR) induced inside the head and the eye due to the electromagnetic field exposure caused by the reader antenna of the transmission system. The analysis was based on numerical finite difference time domain computations using a high resolution anatomical eye model integrated in a modern commercially available anatomical model of a male head. Three different reader antenna configurations, a 7-turn elliptic (30 mm × 50 mm) antenna at 12 mm distance from the eye, a flexible circular antenna (60 mm diameter, 8 turns on 2 mm substrate) directly attached to the skin, and a circular 7-turn antenna (30 mm diameter at 12 mm distance to the eye) were analyzed, respectively. Possible influences of the eye-lid status (closed or opened) and the transponder antenna contained in a contact lens directly attached to the eye were taken into account. The results clearly demonstrated that for typical reader antenna currents required for proper data transmission, the SAR values remain far below the limits for localized exposure of the head, as defined by the International Commission for Non-Ionizing Radiation Protection. Particularly the induced SAR inside the eye was found to be substantially (orders of magnitudes for typical reader antenna currents in the order of 1 A turn) below values which have been reported to be critical with respect to thermally induced adverse health effects in eye tissues. (note)

  17. The In Vivo Effects of the CB1-Positive Allosteric Modulator GAT229 on Intraocular Pressure in Ocular Normotensive and Hypertensive Mice.

    Science.gov (United States)

    Cairns, Elizabeth A; Szczesniak, Anna-Maria; Straiker, Alex J; Kulkarni, Pushkar M; Pertwee, Roger G; Thakur, Ganesh A; Baldridge, William H; Kelly, Melanie E M

    2017-10-01

    Orthosteric cannabinoid receptor 1 (CB 1 ) activation leads to decreases in intraocular pressure (IOP). However, use of orthosteric CB 1 agonists chronically has several disadvantages, limiting their usefulness as clinically relevant drugs. Allosteric modulators interact with topographically distinct sites to orthosteric ligands and may be useful to circumvent some of these disadvantages. The purpose of this study was to investigate the effects of the novel CB 1 -positive allosteric modulator (PAM) GAT229 on IOP. IOP was measured using rebound tonometry in anesthetized normotensive C57Bl/6 mice and in a genetic model of ocular hypertension [nose, eyes, ears (nee) mice] before drug administration, and at 1, 6, and 12 h thereafter. In normotensive mice, topical administration of 5 μL GAT229 alone at either 0.2% or 2% did not reduce IOP. However, a subthreshold dose (0.25%) of the nonselective orthosteric CB 1 agonist WIN 55,212-2, when combined with 0.2% GAT229, significantly reduced IOP compared with vehicle at 6 and 12 h. Similarly, combination of subthreshold Δ 9 -tetrahydrocannabinol (a nonselective orthosteric CB 1 agonist; 1 mg/kg) with topical 0.2% GAT229 produced IOP lowering at 6 h. In nee mice, administration of topical 0.2% GAT229 or 10 mg/kg GAT229 alone was sufficient to lower IOP at 6 and 12 h, and 12 h, respectively. The CB 1 PAM GAT229 reduces IOP in ocular hypertensive mice and enhanced CB 1 -mediated IOP reduction when combined with subthreshold CB 1 orthosteric ligands in normotensive mice. Administration of CB 1 PAMs may provide a novel approach to reduce IOP with fewer of the disadvantages associated with orthosteric CB 1 activation.

  18. Effects of 0.2% brimonidine and 0.2% brimonidine-0.5% timolol on intraocular pressure and pupil size in normal equine eyes.

    Science.gov (United States)

    Von Zup, M; Lassaline, M; Kass, P H; Miller, P E; Thomasy, S M

    2017-11-01

    Brimonidine is an α 2 -adrenergic agonist that decreases aqueous humour production and may increase uveoscleral outflow. It has not been evaluated in normal or glaucomatous equine eyes. To evaluate the efficacy and safety of brimonidine in lowering intraocular pressure (IOP), alone and in conjunction with timolol, as a treatment for equine glaucoma by comparing IOP in normal equine eyes treated with brimonidine and brimonidine-timolol, respectively, with IOP in control eyes. A balanced crossover design with 16 horses receiving one of two treatments, brimonidine and brimonidine-timolol, during each of two 10-day study phases, was used. Four horses were randomly assigned to each of four combinations of treated eye (right or left) and drug order within the two 10-day study phases (brimonidine first or brimonidine-timolol first). Pupil size and conjunctival hyperaemia were assessed twice per day and IOP was measured three times per day using rebound tonometry in both eyes of 16 normal horses throughout two 10-day study periods (brimonidine and brimonidine-timolol) separated by an 18-day washout period. One eye of each horse was treated with brimonidine or brimonidine-timolol and the opposite eye was treated with balanced salt solution (BSS). There were no adverse effects and no significant changes in pupil size in normal equine eyes treated with brimonidine or brimonidine-timolol. Average IOP in normal equine eyes treated with brimonidine (25.6 mmHg) was statistically higher than in eyes treated with brimonidine-timolol (24.6 mmHg) or BSS (24.5 mmHg). However, IOP differences were of ≤1 mmHg and thus not clinically important. Horses with normal eyes may not be as sensitive to the IOP-lowering effects of treatment as horses with glaucoma. Brimonidine and brimonidine-timolol are well tolerated in normal horses but do not decrease IOP. © 2017 EVJ Ltd.

  19. Predictors of Intraocular Pressure After Phacoemulsification in Primary Open-Angle Glaucoma Eyes with Wide Versus Narrower Angles (An American Ophthalmological Society Thesis).

    Science.gov (United States)

    Lin, Shan C; Masis, Marisse; Porco, Travis C; Pasquale, Louis R

    2017-08-01

    To assess if narrower-angle status and anterior segment optical coherence tomography (AS-OCT) parameters can predict intraocular pressure (IOP) drop in primary open-angle glaucoma (POAG) patients after cataract surgery. This was a prospective case series of consecutive cataract surgery patients with POAG and no peripheral anterior synechiae (PAS) using a standardized postoperative management protocol. Preoperatively, patients underwent gonioscopy and AS-OCT. The same glaucoma medication regimen was resumed by 1 month. Potential predictors of IOP reduction included narrower-angle status by gonioscopy and angle-opening distance (AOD500) as well as other AS-OCT parameters. Mixed-effects regression adjusted for use of both eyes and other potential confounders. We enrolled 66 eyes of 40 glaucoma patients. The IOP reduction at 1 year was 4.2±3 mm Hg (26%, P <.001) in the narrower-angle group vs 2.2±3 mm Hg (14%, P <.001) in the wide-angle group ( P =.027 for difference), as classified by gonioscopy. By AOD500 classification, the narrower-angle group had 3.4±3 mm Hg (21%, P <.001) reduction vs 2.5±3 mm Hg (16%, P <.001) in the wide-angle group ( P =.031 for difference). When the entire cohort was assessed, iris thickness, iris area, and lens vault were correlated with increasing IOP reduction at 1 year ( P <.05 for all). In POAG eyes, cataract surgery lowered IOP to a greater degree in the narrower-angle group than in the wide-angle group, and parameters relating to iris thickness and area, as well as lens vault, were correlated with IOP reduction. These findings can guide ophthalmologists in their selection of cataract surgery as a potential management option.

  20. The influence of central corneal thickness and age on intraocular pressure measured by pneumotonometry, non-contact tonometry, the Tono-Pen XL, and Goldmann applanation tonometry

    Science.gov (United States)

    Tonnu, P-A; Ho, T; Newson, T; El Sheikh, A; Sharma, K; White, E; Bunce, C; Garway-Heath, D

    2005-01-01

    Aims: To evaluate the influence of central corneal thickness (CCT) on intraocular pressure (IOP) measurements made with the Goldmann applanation tonometer (GAT), Tono-Pen XL, ocular blood flow tonograph (OBF), and Canon TX-10 non-contact tonometer (NCT). Methods: CCT was recorded for either eye (randomly selected) of each of 105 untreated patients with ocular hypertension and glaucoma attending the glaucoma research unit at Moorfields Eye Hospital. For each of the selected eyes, IOP was measured with the GAT (two observers), Tono-Pen, OBF, and NCT in a randomised order. The relation of measured IOP and of inter-tonometer differences with CCT and subject age was explored by linear regression analysis. Results: A significant association between measured IOP and CCT was found with each instrument. The change in measured IOP for a 10 μm increase in CCT was 0.28, 0.31, 0.38, and 0.46 for the GAT, Tono-Pen, OBF, and NCT, respectively (all p⩽0.05). There was a significant association between the NCT/GAT differences and CCT, with a tendency of NCT to overestimate GAT in eyes with thicker corneas. There was a significant association between GAT/Tono-Pen and OBF/Tono-Pen differences and age, with a tendency of GAT and OBF to overestimate the Tono-Pen in eyes of older subjects. Conclusion: IOP measurement by all four methods is affected by CCT. The NCT is affected by CCT significantly more than the GAT. Subject age has a differential effect on the IOP measurements made by the GAT and OBF compared to the Tono-Pen. PMID:15965165

  1. Vascular and metabolic comorbidities in open-angle glaucoma with low- and high-teen intraocular pressure: a cross-sectional study from South Korea.

    Science.gov (United States)

    Lee, Si Hyung; Kim, Gyu Ah; Lee, Wonseok; Bae, Hyoung Won; Seong, Gong Je; Kim, Chan Yun

    2017-11-01

    To assess the associations between vascular and metabolic comorbidities and the prevalence of open-angle glaucoma (OAG) with low-teen and high-teen intraocular pressure (IOP) in Korea. Cross-sectional data from the Korean National Health and Nutrition Examination Survey from 2008 to 2012 were analysed. Participants diagnosed with OAG with normal IOP were further classified into low-teen IOP (IOP ≤ 15 mmHg) and high-teen IOP (15 mmHg teen IOP groups. The prevalences of hypertension, hyperlipidemia, ischaemic heart disease, stroke and metabolic syndrome were significantly higher among subjects with low-teen OAG compared with normal subjects, while only the prevalences of hypertension and stroke were higher among subjects with high-teen OAG compared with normal subjects. In multivariate logistic regression models adjusted for confounding factors, low-teen OAG was significantly associated with hypertension (OR, 1.68; 95% CI, 1.30-2.18), hyperlipidemia (OR, 1.49; 95% CI, 1.07-2.08), ischaemic heart disease (OR, 1.83; 95% CI, 1.07-3.11), stroke (OR, 1.91; 95% CI, 1.12-3.25) and metabolic syndrome (OR, 1.46; 95% CI, 1.12-1.90). High-teen OAG was only associated with stroke (OR, 2.58; 95% CI, 1.20-5.53). Various vascular and metabolic comorbidities were significantly associated with low-teen OAG, but not with high-teen OAG. These data support the hypothesis that vascular factors play a more significant role in the pathogenesis of OAG with low-teen baseline IOP. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  2. Effect of benzalkonium chloride-free travoprost on intraocular pressure and ocular surface symptoms in patients with glaucoma previously on latanoprost: an open-label study.

    Science.gov (United States)

    Lopes, Joao F; Hubatsch, Douglas A; Amaris, Patricia

    2015-11-12

    Prostaglandin analogs reduce intraocular pressure (IOP) in patients with open-angle glaucoma or ocular hypertension; however, these medications may affect the ocular surface and elicit ocular discomfort when preserved with benzalkonium chloride (BAK). This was an open-label, single-arm study conducted in Latin America from February 2012 to May 2013. Patients with open-angle glaucoma or ocular hypertension who were intolerant of latanoprost 0.005 % were transitioned to receive once-daily BAK-free travoprost 0.004 % containing polyquaternium-1 (Travatan® preserved with POLYQUAD® [PQ], Alcon Laboratories, Inc; Fort Worth, TX) for 12 weeks. Mean change in IOP from baseline (primary efficacy endpoint) and the percentage of patients who achieved a target IOP of ≤18 mmHg were evaluated at all on-therapy visits. Ocular hyperemia, patient preference, and self-projected adherence were assessed at week 12. Adverse events (AEs) were monitored throughout the study. All enrolled patients were included in the analysis (n = 191); the majority of patients (90.6 %, n = 173/191) completed the study. Mean (SD) patient age was 67.5 (11.3) years, and mean baseline IOP was 14.8 mmHg. Mean IOP was reduced by 0.94 mmHg at week 6 and by 1.09 mmHg at week 12 (P glaucoma or ocular hypertension who were intolerant of latanoprost. BAK-free travoprost 0.004 % is a viable alternative for patients who require switching their IOP-lowering medications because of tolerability issues. ClinicalTrials.gov identifier, NCT01510145.

  3. Elevation of intracranial pressure in acute AIDS-related cryptococcal meningitis.

    Science.gov (United States)

    Malessa, R; Krams, M; Hengge, U; Weiller, C; Reinhardt, V; Volbracht, L; Rauhut, F; Brockmeyer, N H

    1994-12-01

    Prior to the AIDS-era, elevation of intracranial pressure was known to be a typical complication of cryptococcal meningitis associated with an increased risk of early death. In AIDS-patients, however, the prevalence and clinical significance of this complication are as yet unclear. We analysed clinical features and courses, CSF findings, serological results and neuroimaging scans in acute cryptococcal meningitis in eight patients with AIDS. Five showed symptoms and signs compatible with raised intracranial pressure, which was life-threatening in one and the most probable cause of death in another. Serial monitoring of intracranial pressure together with repeated CSF analysis revealed that severe intracranial pressure elevation in AIDS related cryptococcal meningitis can occur in spite of effective antimycotic treatment, does not depend on an increased CSF/serum osmolality ratio or CSF overproduction and can be associated with normal cranial computed tomography and magnetic resonance imaging findings. Our data support the hypothesis that CSF reabsorption failure plays the crucial role in the pathophysiological mechanism. External lumbar drainage may be of benefit in selected cases of acute AIDS related cryptococcal meningitis with persisting life threatening elevation in intracranial pressure and normal computed tomogram.

  4. Effects of elevated artificial pneumoperitoneum pressure on invasive blood pressure and levels of blood gases.

    Science.gov (United States)

    Hypolito, Octavio; Azevedo, João Luiz; Gama, Fernanda; Azevedo, Otavio; Miyahira, Susana Abe; Pires, Oscar César; Caldeira, Fabiana Alvarenga; Silva, Thamiris

    2014-01-01

    to evaluate the clinical, hemodynamic, gas analysis and metabolic repercussions of high transient pressures of pneumoperitoneum for a short period of time to ensure greater security for introduction of the first trocar. sixty-seven patients undergoing laparoscopic procedures were studied and randomly distributed in P12 group: n=30 (intraperitoneal pressure [IPP] 12mmHg) and P20 group: n=37 (IPP of 20mmHg). Mean arterial pressure (MAP) was evaluated by catheterization of the radial artery; and through gas analysis, pH, partial pressure of oxygen (PaO2), partial pressure of CO2 (PaCO2), bicarbonate (HCO3) and alkalinity (BE) were evaluated. These parameters were measured in both groups at time zero before pneumoperitoneum (TP0); at time 1 (TP1) when IPP reaches 12mmHg in both groups; at time 2 (TP2) after five min with IPP=12mmHg in P12 and after 5min with IPP=20mmHg at P20; and at time 3 (TP3) after 10min with IPP=12mmHg in P12 and with return of IPP from 20 to 12mmHg, starting 10min after TP1 in P20. Different values from those considered normal for all parameters assessed, or the appearance of atypical organic phenomena, were considered as clinical changes. there were statistically significant differences in P20 group in MAP, pH, HCO3 and BE, but within normal limits. No clinical and pathological changes were observed. high and transient intra-abdominal pressure causes changes in MAP, pH, HCO3 and BE, but without any clinical impact on the patient. Copyright © 2014 Sociedade Brasileira de Anestesiologia. Published by Elsevier Editora Ltda. All rights reserved.

  5. Magnetic Resonance Imaging of Optic Nerve Traction During Adduction in Primary Open-Angle Glaucoma With Normal Intraocular Pressure

    Science.gov (United States)

    Demer, Joseph L.; Clark, Robert A.; Suh, Soh Youn; Giaconi, JoAnn A.; Nouri-Mahdavi, Kouros; Law, Simon K.; Bonelli, Laura; Coleman, Anne L.; Caprioli, Joseph

    2017-01-01

    Purpose We used magnetic resonance imaging (MRI) to ascertain effects of optic nerve (ON) traction in adduction, a phenomenon proposed as neuropathic in primary open-angle glaucoma (POAG). Methods Seventeen patients with POAG and maximal IOP ≤ 20 mm Hg, and 31 controls underwent MRI in central gaze and 20° to 30° abduction and adduction. Optic nerve and sheath area centroids permitted computation of midorbital lengths versus minimum paths. Results Average mean deviation (±SEM) was −8.2 ± 1.2 dB in the 15 patients with POAG having interpretable perimetry. In central gaze, ON path length in POAG was significantly more redundant (104.5 ± 0.4% of geometric minimum) than in controls (102.9 ± 0.4%, P = 2.96 × 10−4). In both groups the ON became significantly straighter in adduction (28.6 ± 0.8° in POAG, 26.8 ± 1.1° in controls) than central gaze and abduction. In adduction, the ON in POAG straightened to 102.0% ± 0.2% of minimum path length versus 104.5% ± 0.4% in central gaze (P = 5.7 × 10−7), compared with controls who straightened to 101.6% ± 0.1% from 102.9% ± 0.3% in central gaze (P = 8.7 × 10−6); and globes retracted 0.73 ± 0.09 mm in POAG, but only 0.07 ± 0.08 mm in controls (P = 8.8 × 10−7). Both effects were confirmed in age-matched controls, and remained significant after correction for significant effects of age and axial globe length (P = 0.005). Conclusions Although tethering and elongation of ON and sheath are normal in adduction, adduction is associated with abnormally great globe retraction in POAG without elevated IOP. Traction in adduction may cause mechanical overloading of the ON head and peripapillary sclera, thus contributing to or resulting from the optic neuropathy of glaucoma independent of IOP. PMID:28829843

  6. Intravitreal triamcinolone for intraocular inflammation and associated macular edema

    Directory of Open Access Journals (Sweden)

    Steven M Couch

    2008-11-01

    Full Text Available Steven M Couch, Sophie J BakriMayo Clinic Department of Ophthalmology, Mayo Clinic, Rochester, MN, USAAbstract: Triamcinolone acetonide (TA is a corticosteroid that has many uses in the treatment of ocular diseases because of its potent anti-inflammatory and anti-permeability actions. Intraocular inflammation broadly referred to as uveitis can result from several causes, including the immune system and after ophthalmic surgery. One of the most common reasons for vision loss with uveitis is macular edema. TA has been used for many years as an intravitreal injection for the treatment of ocular diseases. Several case control studies have been reported showing the efficacy of TA in the treatment of intraocular inflammation and associated macular edema caused by Behcet’s disease, Vogt-Koyanagi-Harada syndrome, sympathetic ophthalmia and white dot syndromes. It has also been shown efficacious in cases of pars planitis and idiopathic posterior uveitis. Some authors have reported its use in postoperative cystoid macular edema. Many of the studies on the use of TA in controlling intraocular inflammation and concomitant macular edema showed its effect to be transient in many patients requiring reinjection. Complications can arise from intravitreal injection of TA including elevated intraocular pressure and cataract. Rarely, it can be associated with infectious and non-infectious endophthalmitis. TA may be useful as an adjuvant in the treatment of uveitis and its associated macular edema, especially in patients resistant or intolerant to standard treatment.Keywords: triamcinolone acetonide, Behcet’s disease, sympathetic ophthalmia, Vogt-Koyanagi-Harada syndrome, white dot syndromes, uveitis, cataract surgery, macular edema, endophthalmitis

  7. Elevated intracranial pressure causes optic nerve and retinal ganglion cell degeneration in mice.

    Science.gov (United States)

    Nusbaum, Derek M; Wu, Samuel M; Frankfort, Benjamin J

    2015-07-01

    The purpose of this study was to develop a novel experimental system for the modulation and measurement of intracranial pressure (ICP), and to use this system to assess the impact of elevated ICP on the optic nerve and retinal ganglion cells (RGCs) in CD1 mice. This system involved surgical implantation of an infusion cannula and a radiowave based pressure monitoring probe through the skull and into the subarachnoid space. The infusion cannula was used to increase ICP, which was measured by the probe and transmitted to a nearby receiver. The system provided robust and consistent ICP waveforms, was well tolerated, and was stable over time. ICP was elevated to approximately 30 mmHg for one week, after which we assessed changes in optic nerve structure with transmission electron microscopy in cross section and RGC numbers with antibody staining in retinal flat mounts. ICP elevation resulted in optic nerve axonal loss and disorganization, as well as RGC soma loss. We conclude that the controlled manipulation of ICP in active, awake mice is possible, despite their small size. Furthermore, ICP elevation results in visual system phenotypes of optic nerve and RGC degeneration, suggesting that this model can be used to study the impact of ICP on the visual system. Potentially, this model can also be used to study the relationship between ICP and IOP, as well diseases impacted by ICP variation such as glaucoma, idiopathic intracranial hypertension, and the spaceflight-related visual impairment intracranial pressure syndrome. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Effect of elevated blood pressure on quality of life in children with chronic kidney disease.

    Science.gov (United States)

    Wong, Cynthia; Gerson, Arlene; Hooper, Stephen R; Matheson, Matthew; Lande, Marc; Kupferman, Juan; Furth, Susan; Warady, Bradley; Flynn, Joseph

    2016-07-01

    Although hypertension is known to have an adverse impact on health-related quality of life (HRQoL) in adults, little is known about the effects of hypertension and use of antihypertensive medications on HRQoL in hypertensive children with chronic kidney disease (CKD). Cross-sectional and longitudinal assessment of impact of elevated blood pressure (BP) and antihypertensive medication use on HRQoL scores obtained in children enrolled in the Chronic Kidney Disease in Children (CKiD) Study. Blood pressure was measured both manually and by ambulatory blood pressure monitoring. HRQoL was assessed with the PedsQL survey. The study sample included 551 participants with sufficient data for cross-sectional and longitudinal analyses. Cross-sectional analysis of presence of prehypertension or hypertension and impact on HRQoL found mild associations between elevated BP and HRQoL scores with overall PedsQL parent and child scores averaging 79 vs. 76.5 and 83 vs. 78.5, respectively. However, no associations persisted under longitudinal multivariate analysis. Despite apparent small effects of elevated BP on HRQoL at baseline, no association was found between the presence of elevated BP and HRQoL over time in children with mild-to-moderate CKD. In addition, antihypertensive medication use did not appear to have an impact on HRQoL in this population.

  9. Noninvasive Monitoring of Elevated Intramuscular Pressure in a Model Compartment Syndrome via Quantitative Fascial Motion

    Science.gov (United States)

    Lynch, John E.; Lynch, John K.; Cole, Steven L.; Carter, Jonathan A.; Hargens, Alan R.

    2009-01-01

    Compartment syndromes, caused by elevated intramuscular pressure (IMP) and resulting from trauma or chronic overuse, frequently require invasive IMP monitoring for accurate diagnosis. Our objective is to test a non-invasive ultrasound technique for estimating IMP based on fascial displacement waveforms from arterial blood pressure pulses. In this study, IMP was increased in the legs of 23 healthy adult subjects up to 80 mmHg using two blood pressure cuffs covering the region from the knee to the ankle. Receiver operator characteristic (ROC) curves and recursive partitioning were used to determine the sensitivity and specificity of diagnosing elevated IMP using fascial displacement. For one ROC curve, in which several ultrasonic measurement parameters were used along with subject body mass index and blood pressure, the sensitivity and specificity for diagnosing normal IMP (below 30 mmHg) from elevated IMP (30 mmHg and up) was 0.61 and 0.94 respectively. Recursive partitioning, in which IMP was divided into three ranges (normal = 50 mmHg), resulted in improved diagnostic sensitivity (0.77) with almost no change in specificity (0.93). PMID:18979529

  10. The impact of corneal edema on intraocular pressure measurements using goldmann applanation tonometry, Tono-Pen XL, iCare, and ORA: an in vitro model.

    Science.gov (United States)

    Neuburger, Matthias; Maier, Philip; Böhringer, Daniel; Reinhard, Thomas; F Jordan, Jens

    2013-09-01

    Among other corneal biomechanical properties, Goldmann applanation tonometry (GAT) has been shown to depend on corneal edema. New tonometry devices have been designed, such as the Tono-Pen XL, iCare, and ocular response analyzer (ORA), to measure the intraocular pressure (IOP) accurately. This study aims to investigate the influence of corneal edema on the accuracy of these IOP-measuring devices in an in vitro model. A model of an artificial anterior chamber was developed using a guided trephination system. Eight donor corneas not suitable for keratoplasty were clamped into this artificial anterior chamber. All corneas showed signs of stromal edema. Intracameral pressure (ICP) was adjusted manometrically to 10, 20, 30, 40, and 50 mm Hg. The central corneal thickness (CCT) was determined by ultrasonic pachymetry. For each manometrically defined ICP, tonometry was performed using the iCare, Tono-Pen XL, GAT, and ORA. The mean CCT increased from 616.1±29.6 µm to 626.9±36.1 µm. At 10 mm Hg, GAT yielded a higher ICP than those manometrically adjusted (10.4±3.3 mm Hg); at all other ICP levels, GAT yielded lower ICP levels than those adjusted. The Tono-Pen XL and iCare showed the greatest difference at 10 mm Hg, with the Tono-Pen XL yielding a value of 14.0±4.0 mm Hg and the iCare yielding a value of 12.5±2.6 mm Hg. All other results of the 2 devices fell within a range of ±2 mm Hg from the adjusted ICP. The ORA provided accurate results only at "physiological" ICP levels with a maximum difference of 2.6 mm Hg at 30 mm Hg. At higher ICP levels, corneal hysteresis decreased significantly with increasing ICP. None of the measurement devices revealed a statistically relevant dependence on CCT in this experimental setting. The Tono-Pen XL and the iCare yielded the most accurate ICP values across all the adjusted ICP values. This may be because of their relatively small contact area with the cornea and, consequently, greater independence from corneal biomechanical

  11. Use of oral antihypertensive medication preceding blood pressure elevation in hospitalized patients

    Directory of Open Access Journals (Sweden)

    Macedo Cristiano Ricardo Bastos de

    2001-01-01

    Full Text Available OBJECTIVE: To evaluate the frequency of oral antihypertensive medication preceding the increase in blood pressure in patients in a university hospital, the drug of choice, and the maintained use of antihypertensive medication. METHODS: Data from January to June 1997 from the University Hospital Professor Edgard Santos Pharmacy concerning the prescriptions of all inpatients were used. Variables included in the analysis were: antihypertensive medication prescription preceding increase in blood pressure, type of antihypertensive medication, gender, clinical or surgical wards, and the presence of maintained antihypertensive medication. RESULTS: The hospital admitted 2,532 patients, 1,468 in surgical wards and 818 in medical wards. Antihypertensive medication prescription preceding pressure increase was observed in 578 patients (22.8%. Nifedipine was used in 553 (95.7% and captopril in 25 (4.3%. In 50.7% of patients, prescription of antihypertensive medication was not associated with maintained antihypertensive medication. Prescription of antihypertensive drugs preceding elevation of blood pressure was significantly (p<0.001 more frequent on the surgical floor (27.5%; 405/1468 than on the medical floor (14.3%; 117/818. The frequency of prescription of antihypertensive drugs preceding elevation of blood pressure without maintained antihypertensive drugs and the ratio between the number of prescriptions of nifedipine and captopril were greater in surgical wards. CONCLUSION: The use of antihypertensive medication, preceding elevation of blood pressure (22.8% observed in admitted patients is not supported by scientific evidence. The high frequency of this practice may be even greater in nonuniversity hospitals.

  12. Diagnostic Accuracy of Optic Nerve Ultrasonography and Ophthalmoscopy in Prediction of Elevated Intracranial Pressure

    Directory of Open Access Journals (Sweden)

    Keihan Golshani

    2015-05-01

    Full Text Available Introduction: Elevated intracranial pressure (ICP is a major and potentially lethal disorder in patients admitted to the emergency department (ED. Several methods are being used to investigate for elevated ICP. Here we assessed and compared the diagnostic accuracy of two existing tools of ophthalmoscopy and optic nerve ultrasonography in detection of elevated ICP. Methods: 131 participants with probable elevation of ICP referred to the emergency department of Al-Zahra Hospital, Isfahan, Iran, from 2012 to 2014, were enrolled. Brain computed tomography (CT scan, ultrasonography of optic nerve sheath, and ophthalmoscopy were performed for them. The optic nerves sheath with diameter more than 5 millimeters was considered as elevated ICP. Widening of optic nerve, ocular venous engorgement, blurring, hemorrhage over optic disk, elevation of optic disk, and retinal venous tortuosity were recorded as evidences of ICP rising in ophthalmoscopy. Diagnostic accuracy of the two tools in prediction of ICP rising were compared with the results of brain CT scan as a gold standard. Results: The mean age of participants was 46.29 ± 10 years (77% male. The number of diagnosed elevated ICPs with ophthalmoscopy and ultrasound were 98 (74.8% and 102 (77.9% cases, respectively. The calculated sensitivity and specificity of ophthalmoscopy and ultrasonography in detection of ICP rising were 100.0% (95% CI: 88.6-100.0 and 35.4% (95% CI: 26.0-46.2, 100.0% (95% CI: 84.0-100.0 and 31.9% (95% CI: 23.0-41.7, respectively. Conclusion: The present study reveals that bedside ultrasonography of optic nerve sheath and ophthalmoscopy have enough accuracy for screening of patients with probable elevation of ICP. Of course, it should be considered that despite of high sensitivity of both tools, their specificity is low.

  13. Integration optimisation of elevated pressure air separation unit with gas turbine in an IGCC power plant

    International Nuclear Information System (INIS)

    Han, Long; Deng, Guangyi; Li, Zheng; Wang, Qinhui; Ileleji, Klein E.

    2017-01-01

    Highlights: • IGCC thermodynamic model was setup carefully. • Simulations focus on integration between an elevated pressure ASU with gas turbine. • Different recommended solutions from those of low pressure ASUs are figured out. • Full N 2 injection and 80% air extraction was suggested as the optimum integration. - Abstract: The integration optimisation between an elevated pressure air separation unit (EP-ASU) and gas turbine is beneficial to promote net efficiency of an integrated gasification combined cycle (IGCC) power plant. This study sets up the thermodynamic model for a 400 MW plant specially coupled with an EP-ASU, aiming to examine system performances under different integrations and acquire the optimum solution. Influences of air extraction rate at conditions of without, partial and full N 2 injection, as well as the effects of N 2 injection rate when adopting separate ASU, partial and full integrated ASU were both analysed. Special attention has been paid to performance differences between utilising an EP-ASU and a low pressure unit. Results indicated that integration solution with a separate EP-ASU or without N 2 injection would not be reasonable. Among various recommended solutions for different integration conditions, N 2 injection rate increased with the growth of air extraction rate. The integration with an air extraction rate of 80% and full N 2 injection was suggested as the optimum solution. It is concluded that the optimum integration solution when adopting an EP-ASU is different from that using a low pressure one.

  14. Acute Retention of Urine Following Intraocular Surgery | Nwosu ...

    African Journals Online (AJOL)

    Hyperosmolar agents and carbonic anhydrase inhibitors are used to lower the intraocular pressure and thus minimize the chances of vitreous loss during intraocular surgery. However, these agents could precipitate urinary retention. This is a report on two elderly men who had perioperative acute urinary retention following ...

  15. Evaluación del espesor corneal central y su influencia en la presión intraocular en pacientes del Hospital "Dr. Miguel Enríquez" Evaluation of the central corneal thickness and its impact on the intraocular pressure of patients in "Dr. Miguel Enriquez" hospital

    Directory of Open Access Journals (Sweden)

    María Teresa Arrronte Alarcón

    2012-01-01

    Full Text Available Objetivo: evaluar el espesor corneal central en sujetos sanos, hipertensos oculares, sospechosos de glaucoma y glaucomatosos, y su influencia en la presión intraocular. Métodos: se realizó un estudio descriptivo y transversal que incluyó 708 ojos de 356 sujetos que acudieron al servicio de oftalmología del Hospital Universitario "Dr. Miguel Enríquez" entre enero y diciembre de 2010. A los pacientes se les midió el espesor corneal central con paquimetría ultrasónica (paquímetro US 4000. El resto de la información se obtuvo a partir de las historias clínicas de los pacientes. Resultados: Los hipertensos oculares presentaron córneas gruesas (p=0,07; el mayor número de casos que tenían diagnóstico de sospecha de glaucoma y de glaucoma primario de ángulo abierto presentaron un grosor corneal delgado (p=0,62 y p=0,08 respectivamente. Si no se hubiese tenido en cuenta el factor de corrección para evaluar la presión intraocular se encontraría 48,1 % de los glaucomatosos y 31,5 % de los hipertensos oculares con diagnóstico inadecuado (pObjective: to evaluate the central corneal thickness in healthy individuals, in persons with ocular hypertension, and in suspected glaucoma and glaucomatous people, and its influence in intraocular pressure. Methods: a cross-sectional and descriptive study was performed in 708 eyes from 356 people who had been seen at ophthalmology service of “Dr. Miguel Enríquez”, university hospital from January to December, 2010. Their central corneal thickness was measured with ultrasonic pachymetry (pachymeter US 4000. The rest of the information came from the clinical histories of the patients. Results: Most of the ocular hypertensives presented thick corneas (p=0,07; a high number of cases that had diagnosis of glaucoma suspicion and primary open-angle glaucoma showed thin corneas (p=0,62 and (p=0,08 respectively. If the correction factor to evaluate the IOP had not been considered, then 48,1 % of the

  16. Two kinds of urinary continence reflexes during abrupt elevation of intravesical pressure in rats

    OpenAIRE

    Kamo, Izumi; Kaiho, Yasuhiro; Miyazato, Minoru; Torimoto, Kazumasa; Yoshimura, Naoki

    2009-01-01

    Urethral closure mechanisms during abrupt elevation of intravesical pressure (Pves) were investigated. During sneezing, the middle urethral closing response was observed and it still remained after opening the abdomen. The middle urethral response was almost completely abolished after bilateral transection of somatic nerves innervating the external urethral sphincter and the pelvic floor muscles, while bilateral transection of both pelvic nerves and hypogastric nerves had no effects. Somatic ...

  17. Elevation devices for the prevention of heel pressure ulcers: a review.

    Science.gov (United States)

    Clegg, Rosie; Palfreyman, Simon

    2014-11-01

    The objective of this systematic literature review was to gain insight into the effectiveness of off-loading devices to prevent heel pressure ulcers within the acute hospital setting. Heels have been identified as the second most common site for pressure ulcers. Devices which off-load pressure can include pillows, wedges and boots. It is unclear as to which method or device is best at preventing pressure ulcers. A systematic review was carried out through the search of electronic databases and bibliographies of relevant publications. Randomised controlled trials (RCTs) and systematic reviews that compared devices which off-load heels to prevent pressure ulcers were identified. A total of five studies were included in the review. The methodological quality of the studies was generally poor. The studies reported that heel-boot elevation devices appeared more beneficial. However, poor compliance with wearing the devices was identified, as well as a perceived increased risk of falls. There were little data on cost-effectiveness. There is little high-quality trial evidence to support the routine use of heel devices to prevent pressure ulcers. However, they may have a role to play within a multifaceted programme of pressure-ulcer prevention.

  18. Using smartphone pressure sensors to measure vertical velocities of elevators, stairways, and drones

    Science.gov (United States)

    Monteiro, Martín; Martí, Arturo C.

    2017-01-01

    We measure the vertical velocities of elevators, pedestrians climbing stairs, and drones (flying unmanned aerial vehicles), by means of smartphone pressure sensors. The barometric pressure obtained with the smartphone is related to the altitude of the device via the hydrostatic approximation. From the altitude values, vertical velocities are derived. The approximation considered is valid in the first hundred meters of the inner layers of the atmosphere. In addition to pressure, acceleration values were also recorded using the built-in accelerometer. Numerical integration was performed, obtaining both vertical velocity and altitude. We show that data obtained using the pressure sensor is significantly less noisy than that obtained using the accelerometer. Error accumulation is also evident in the numerical integration of the acceleration values. In the proposed experiments, the pressure sensor also outperforms GPS, because this sensor does not receive satellite signals indoors and, in general, the operating frequency is considerably lower than that of the pressure sensor. In the cases in which it is possible, comparison with reference values taken from the architectural plans of buildings validates the results obtained using the pressure sensor. This proposal is ideally performed as an external or outreach activity with students to gain insight about fundamental questions in mechanics, fluids, and thermodynamics.

  19. Soot particle size measurements in ethylene diffusion flames at elevated pressures

    KAUST Repository

    Steinmetz, Scott

    2016-05-07

    Soot particle size is investigated in laminar nitrogen-diluted ethylene coflow diffusion flames at 4, 8, 12 and 16 atm. Line of sight attenuation and scattering are used to measure two-dimensional soot volume fraction and particle size fields for the first time at elevated pressures. Soot volume fraction dependence on pressure is consistent with the observations of similar studies, scaling approximately with the square of pressure. Scattering intensity is analyzed through Rayleigh and Rayleigh-Debye-Gans polydisperse fractal aggregate theories to provide two estimates of particle size. An increase in overall particle sizes with pressure is found, consistent with similar one-dimensional studies. Particle diameters in the annulus of the flame increase faster with pressure than those on centerline. Contrary to previous studies, the dependence of particle size on pressure was found to taper off between 8 and 12 atm, with little observed growth beyond 12 atm. The measurements provide additional data for one of the International Sooting Flame (ISF) workshop\\'s target pressurized flames.

  20. Agreement and reproducibility of Tono-Pen XL tip covered with ocufilm and fingertip of surgical glove in intra-ocular pressure measurement.

    Science.gov (United States)

    Sayawat, Niphon; Duangnumsawang, Duangdao

    2012-04-01

    To compare the effect of using the fingertip of a surgical glove over Ocufilm (Reichert Technologies, NY, USA) on the agreement and reproducibility of measuring intra-ocular pressure (IOP) by the Tono-Pen XL (Reichert Technologies, NY USA). Experimental, clinical study. Patients were randomized into two groups to receive IOP measurements using Tono-Pen XL with two different types of tip covers. In Group 1, the IOP of the right eyes were first measured using Ocufilm as the tip cover followed by using the fingertip of a surgical glove. As for the left eyes, the tip of the surgical glove was used first, followed by use of Ocufilm. In Group 2, the IOP of the right eyes was first measured using the tip of the surgical glove,followed by use of Ocufilm, while for the left eye the latter was used first, followed by the tip of the surgical glove. A single operator measured the IOP in each eye twice using each type of tip cover. Agreement between the Tono-Pen XL measurements using the two different tip covers was analyzed using the Bland-Altman analysis. The difference between the repeated measures was assessed for reproducibility of the Tono-Pen XL measurements with regard to each type of tip covers. 100 patients (200 eyes) were recruited into the present study. The mean difference of IOP taken by the Tono-Pen XL covered with Ocufilm and the fingertip of a surgical glove was -0.21 mmHg (95% CI: -0.36 to -0.05). The limits of agreement (confidence interval 95%) as calculated by the Bland-Altman plots for Ocufilm-Fingertip of a surgical glove was -2.43 to +2.02 mmHg. The coefficient of repeatability of the Ocufilm vs. the surgical glove was nearly the same (1.74 vs. 2.37, respectively). A significant agreement exists between using Ocufilm and the fingertip of a surgical glove to cover the tip of a Tono-Pen XL for measuring IOP The coefficient of repeatability was comparable between the two different types of tip covers. When measuring IOP the tip of a Tono-Pen XL could

  1. The influence of central corneal thickness and corneal curvature on intraocular pressure measured by tono-pen and rebound tonometer in children.

    Science.gov (United States)

    Sahin, Afsun; Basmak, Hikmet; Yildirim, Nilgun

    2008-01-01

    To find out the effect of central corneal thickness (CCT) and radius of the corneal curvature on intraocular pressure (IOP) measurements using rebound tonometer (RBT) and Tono-Pen in healthy schoolchildren. IOP was measured with Tono-Pen and RBT, respectively, in 165 healthy schoolchildren with a mean age 9.8+/-3.1 (range: 7 to 12 y) years. Corneal radius of curvature (in mm) was determined using a keratometer before CCT and IOP measurements. CCT was measured using an ultrasonic pachymeter after all IOP determinations had been made. The effect of CCT, radius of the corneal curvature, and sex on measured IOP was evaluated by linear regression analysis. The mean IOP readings were 17.47+/-2.7 mm Hg using Tono-Pen, and 16.81+/-3.1 mm Hg using RBT. Tono-Pen measured IOP values slightly greater than that of RBT (P=0.006). Mean CCT was found to be 561.37+/-33 microm. A significant association between measured IOP and CCT was found with each device (r=0.220 for the Tono-Pen, r=0.373 for the RBT; P=0.006 for the Tono-Pen and P<0.0001 for the RBT). The IOP increased 2.2 and 3.7 mm Hg for every 100-microm increase in CCT for the Tono-Pen and the RBT, respectively. The relation between IOP and CCT was not different for boys and girls. Mean radius of the corneal curvature readings was 7.68+/-0.41 mm (42.75+/-1.37 D) for both sexes. There was no significant relationship between either the mean corneal curvature readings, or CCT and IOP (r=0.02; P=0.4 for CCT and r=0.01; P=0.5 for IOP). Both the Tono-Pen and RBT have a systematic error in IOP readings caused by its dependence on CCT. The CCT measurements should be considered to ensure proper interpretation of IOP measurements in children, like in adults. The corneal radius of curvature had no significant effect on measured IOP with each device.

  2. Comparison of intraocular pressure measurements between the Tono-Pen XL® and Perkins® applanation tonometers in dogs and cats.

    Science.gov (United States)

    Andrade, Silvia Franco; Palozzi, Rodrigo Jesus; Giuffrida, Rogério; de Campos, Renata Juliane; Santos, Gabriela de Campos; Fukui, Rosimery Missuzu

    2012-03-01

    To compare the accuracy between two applanation tonometers, Tono-Pen XL(®) and Perkins(®), in ophthalmoscopically normal dogs and cats. Both eyes of 25 conscious and healthy dogs and cats were evaluated. Both eyes of five dogs and cats immediately after sacrifice were used as controls for the postmortem study. In conscious animals, the tonometry was performed with topical anesthesia using 0.5% proxymetacaine eye drops for both tonometers and 1% fluorescein eye drops for the Perkins tonometer. Readings of intraocular pressure (IOP) in the postmortem study were taken using manometry and tonometry by Tono-Pen XL(®) and Perkins(®). The correlation coefficient (r(2) ) in dogs between manometry and applanation tonometers Tono-Pen XL(®) and Perkins(®) were, respectively, 0.896 and 0.981 and in cats were 0.905 and 0.988. The mean IOP values in conscious dogs with Tono-Pen XL(®) and Perkins(®) were, respectively, 17.5 ± 3.7 mmHg (10.0-25.0 mmHg) and 15.3 ± 2.1 mmHg (12.0-19.8 mmHg) and in conscious cats were 16.8 ± 3.6 mmHg (10.5-24.5 mmHg) and 15.5 ± 1.3 mmHg (13.0-18.5 mmHg). There was a strong correlation between the IOP values obtained by direct ocular manometry and the Tono-Pen XL(®) and Perkins(®) tonometers in dogs and cats. There was no statistically significant difference between the mean IOP obtained with both tonometers in conscious animals, there was, however, a difference between the minimum and mainly in the maximum values that were on average 5-6 mmHg higher with Tono-Pen XL(®) than those measured with Perkins(®), which justifies a table of normal values differentiated for each tonometer. © 2012 American College of Veterinary Ophthalmologists.

  3. Elevated Plasma Endothelin-1 and Pulmonary Arterial Pressure in Children Exposed to Air Pollution

    Science.gov (United States)

    Calderón-Garcidueñas, Lilian; Vincent, Renaud; Mora-Tiscareño, Antonieta; Franco-Lira, Maricela; Henríquez-Roldán, Carlos; Barragán-Mejía, Gerardo; Garrido-García, Luis; Camacho-Reyes, Laura; Valencia-Salazar, Gildardo; Paredes, Rogelio; Romero, Lina; Osnaya, Hector; Villarreal-Calderón, Rafael; Torres-Jardón, Ricardo; Hazucha, Milan J.; Reed, William

    2007-01-01

    Background Controlled exposures of animals and humans to particulate matter (PM) or ozone air pollution cause an increase in plasma levels of endothelin-1, a potent vasoconstrictor that regulates pulmonary arterial pressure. Objectives The primary objective of this field study was to determine whether Mexico City children, who are chronically exposed to levels of PM and O3 that exceed the United States air quality standards, have elevated plasma endothelin-1 levels and pulmonary arterial pressures. Methods We conducted a study of 81 children, 7.9 ± 1.3 years of age, lifelong residents of either northeast (n = 19) or southwest (n = 40) Mexico City or Polotitlán (n = 22), a control city with PM and O3 levels below the U.S. air quality standards. Clinical histories, physical examinations, and complete blood counts were done. Plasma endothelin-1 concentrations were determined by immunoassay, and pulmonary arterial pressures were measured by Doppler echocardiography. Results Mexico City children had higher plasma endothelin-1 concentrations compared with controls (p < 0.001). Mean pulmonary arterial pressure was elevated in children from both northeast (p < 0.001) and southwest (p < 0.05) Mexico City compared with controls. Endothelin-1 levels in Mexico City children were positively correlated with daily outdoor hours (p = 0.012), and 7-day cumulative levels of PM air pollution < 2.5 μm in aerodynamic diameter (PM2.5) before endothelin-1 measurement (p = 0.03). Conclusions Chronic exposure of children to PM2.5 is associated with increased levels of circulating endothelin-1 and elevated mean pulmonary arterial pressure. PMID:17687455

  4. PATTERN OF INTRAOCULAR PRESSURE IN

    African Journals Online (AJOL)

    The demographic characterístics and laterality of the IOP measured were documented. Excluded were: patients with glaucoma, ocular trauma, ocular surgery, ocular inflammation, retinal/choroidal detachment, family history of glaucoma, myopia; patients on corticosteroid or antiglaucoma therapy; patients wh had had ar.

  5. Emotional dampening in persons with elevated blood pressure: affect dysregulation and risk for hypertension.

    Science.gov (United States)

    McCubbin, James A; Loveless, James P; Graham, Jack G; Hall, Gabrielle A; Bart, Ryan M; Moore, DeWayne D; Merritt, Marcellus M; Lane, Richard D; Thayer, Julian F

    2014-02-01

    Persons with higher blood pressure have emotional dampening in some contexts. This may reflect interactive changes in central nervous system control of affect and autonomic function in the early stages of hypertension development. The purpose of this study is to determine the independence of cardiovascular emotional dampening from alexithymia to better understand the role of affect dysregulation in blood pressure elevations. Ninety-six normotensives were assessed for resting systolic and diastolic (DBP) blood pressure, recognition of emotions in faces and sentences using the Perception of Affect Task (PAT), alexithymia, anxiety, and defensiveness. Resting DBP significantly predicted PAT emotion recognition accuracy in men after adjustment for age, self-reported affect, and alexithymia. Cardiovascular emotional dampening is independent of alexithymia and affect in men. Dampened emotion recognition could potentially influence interpersonal communication and psychosocial distress, thereby further contributing to BP dysregulation and increased cardiovascular risk.

  6. Experimental Investigation of Minimum Film Boiling Temperature for Vertical Cylinders at Elevated Pressures

    International Nuclear Information System (INIS)

    Peterson, L.J.; Bajorek, S.M.

    2002-01-01

    The minimum film boiling temperature, T min , is of particular interest to nuclear safety. Many thermal-hydraulics codes depend on an accurate estimation of T min to determine the appropriate heat transfer regime. Heat transfer coefficients increase considerably when the surface temperature decreases below T min . This paper presents the results of an experimental investigation of T min for vertical cylinders at elevated pressure. While several previous studies have investigated T min under various conditions, relatively few have generated experimental data at pressures above atmospheric. As a result, correlations for T min often predict unrealistic values at high pressure. The present investigation has generated an experimental database examining the effects of pressure, material, subcooling, surface roughness, and oxidation on T min . The experimental apparatus and test specimens are described in addition to the evaluation procedure. T min results are reported in this paper for Type 316 stainless steel, Type 1018 carbon steel, and Zircaloy-4. Pressure was varied from 0.101 MPa to 3.0 MPa, and liquid subcooling was ranged up to 30 deg. C. Zircaloy-4 samples with a thick oxide layer were also tested. The results show that T min increases with pressure, liquid subcooling, surface roughness, and surface oxidation. T min is a strong function of pressure at low pressure, but asymptotically approaches a constant value as pressure increases. T min is also a function of surface material properties, with Zircaloy-4 being found to have the highest minimum film boiling temperature compared to carbon steel and stainless steel. For Zircaloy-4, an oxide layer was found to significantly increase T min . (authors)

  7. Elevated pulse pressure is associated with hemolysis, proteinuria and chronic kidney disease in sickle cell disease.

    Directory of Open Access Journals (Sweden)

    Enrico M Novelli

    Full Text Available A seeming paradox of sickle cell disease is that patients do not suffer from a high prevalence of systemic hypertension in spite of endothelial dysfunction, chronic inflammation and vasculopathy. However, some patients do develop systolic hypertension and increased pulse pressure, an increasingly recognized major cardiovascular risk factor in other populations. Hence, we hypothesized that pulse pressure, unlike other blood pressure parameters, is independently associated with markers of hemolytic anemia and cardiovascular risk in sickle cell disease. We analyzed the correlates of pulse pressure in patients (n  =  661 enrolled in a multicenter international sickle cell trial. Markers of hemolysis were analyzed as independent variables and as a previously validated hemolytic index that includes multiple variables. We found that pulse pressure, not systolic, diastolic or mean arterial pressure, independently correlated with high reticulocyte count (beta  =  2.37, p  =  0.02 and high hemolytic index (beta  =  1.53, p = 0.002 in patients with homozygous sickle cell disease in two multiple linear regression models which include the markers of hemolysis as independent variables or the hemolytic index, respectively. Pulse pressure was also independently associated with elevated serum creatinine (beta  =  3.21, p  =  0.02, and with proteinuria (beta  =  2.52, p  =  0.04. These results from the largest sickle cell disease cohort to date since the Cooperative Study of Sickle Cell Disease show that pulse pressure is independently associated with hemolysis, proteinuria and chronic kidney disease. We propose that high pulse pressure may be a risk factor for clinical complications of vascular dysfunction in sickle cell disease. Longitudinal and mechanistic studies should be conducted to confirm these hypotheses.

  8. Biliary glutathione and some amino acids are markedly diminished when biliary pressure is elevated.

    Science.gov (United States)

    Moslen, M T; Kanz, M F; Bhatia, J; Smith, C V; Rassin, D K

    1994-08-01

    We studied the effects of a transient elevation in biliary pressure on biliary glutathione and amino acids in rats. Other biliary solutes monitored were total bile salt, Pi, which is a putative marker of paracellular leakage, and glucose, which is reabsorbed from the biliary tract. Experiments were carried out on anesthetized rats intraduodenally infused with taurocholate to maintain bile flow during a 2-hr basal period, a 4-hr pressure period during which the bile duct cannula was elevated until bile flow decreased to 1/3 the basal rate, and a 2-hr period after release of hydrostatic biliary pressure. We found that pressure treatment caused biliary concentrations of glutathione to progressively decrease by 80%, while biliary Pi rapidly rose approximately 3- to 4-fold, bile salt gradually increased approximately 3-fold, and biliary glucose concentration progressively rose 15-fold. HPLC analysis of monobromobimane-derivatized biliary thiols indicated that the decline in biliary glutathione was not accompanied by an increase in its breakdown products, cysteine and cysteinylglycine. Pressure treatment led to four patterns of change in biliary amino acid concentrations: (1) increases of 29 to 76% for the basic amino acids lysine and arginine, which have very low bile/plasma ratios of about 0.1; (2) no change for the more water soluble amino acids with bile/plasma ratios close to 1.0, e.g., histidine and urea; (3) modest decreases of 16 to 48% for a variety of amino acids including serine, glutamate, and glycine; and (4) marked, progressive decreases of > 50% for aromatic and branched chain amino acids. By 2 hr after release of pressure, only the alterations in biliary glucose and some amino acids, particularly the branched chains, persisted. This is the first report of cholestasis-induced alterations in biliary amino acids.

  9. Myocardial Ischaemia, Coronary Atherosclerosis and Pulmonary Pressure Elevation in Antiphospholipid Syndrome Patients.

    Science.gov (United States)

    Padjas, Agnieszka; Płazak, Wojciech; Celińska-Lowenhoff, Magdalena; Mazurek, Adam; Perricone, Carlo; Podolec, Piotr; Musiał, Jacek

    2016-01-01

    Thrombotic events in antiphospholipid syndrome (APS) involve venous and arterial circulation with the possible involvement of coronary or pulmonary microcirculation. To evaluate the influence of antiphospholipid antibodies (aPL) and on myocardial ischaemia assessed by single-photon emission computerized tomography (SPECT), coronary atherosclerosis assessed by multidetector computerized tomography (MDCT) and pulmonary pressure assessed by transthoracic echocardiography (TTE) in patients with primary antiphospholipid syndrome (PAPS). TTE, SPECT (Tc 99m sestamibi) and MDCT-based coronary calcium scoring were performed in 26 consecutive PAPS patients (20 females, 6 males, aged 20-61, mean 39.7) without any signs of other autoimmunological disease and without clinical symptoms of heart disease. Out of 26 patients, TEE showed normal left and right ventricle function in 25 (96.2%) and elevated (≥ 30 mm Hg) right ventricle systolic pressure in 7 (26.9%) patients. SPECT revealed myocardial perfusion defects in 15 (57.7%) patients: exercise-induced in 6 (23.1%) and persistent in 11 (42.3%). MDCT revealed coronary calcifications in 4 (15.4%) patients. The number of plaques ranged from 1 to 11 (median 2), volume 3-201.7 mm³ (median 7), calcium scores 1.3-202.6 (median 5.7). In the group with perfusion defects or coronary calcifications (n = 15), all the patients showed elevated aCL IgG. In most of the relatively young APS patients, without any symptoms of ischemic heart disease, SPECT showed myocardial perfusion defects, and coronary calcifications in 1/6 of them. Right ventricle systolic pressure was elevated in 1/4 of APS patients. These pathologies, well known as cardiovascular risk markers, were associated with elevated levels of the IgG class of both anti-cardiolipin and antiB2 GPI antibodies. Thus, in a high percentage of APS patients, clinically silent myocardial ischaemia, pulmonary pressure elevation and coronary atherosclerosis are present and related to the

  10. Systematic review of decreased intracranial pressure with optimal head elevation in postcraniotomy patients: a meta-analysis.

    Science.gov (United States)

    Jiang, Yan; Ye, Zeng pan-pan; You, Chao; Hu, Xin; Liu, Yi; Li, Hao; Lin, Sen; Li, Ji-Pin

    2015-10-01

    To determine an optimal head elevation degree to decrease intracranial pressure in postcraniotomy patients by meta-analysis. A change in head position can lead to a change in intracranial pressure; however, there are conflicting data regarding the optimal degree of elevation that decreases intracranial pressure in postcraniotomy patients. Quantitative systematic review with meta-analysis following Cochrane methods. The data were collected during 2014; three databases (PubMed, Embase and China National Knowledge Internet) were searched for published and unpublished studies in English. The bibliographies of the articles were also reviewed. The inclusion criteria referred to different elevation degrees and effects on intracranial pressure in postcraniotomy patients. According to pre-determined inclusion criteria and exclusion criteria, two reviewers extracted the eligible studies using a standard data form. These included a total of 237 participants who were included in the meta-analysis. (1) Compared with 0 degree: 10, 15, 30 and 45 degrees of head elevation resulted in lower intracranial pressure. (2) Intracranial pressure at 30 degrees was not significantly different in comparison to 45 degrees and was lower than that at 10 and 15 degrees. Patients with increased intracranial pressure significantly benefitted from a head elevation of 10, 15, 30 and 45 degrees compared with 0 degrees. A head elevation of 30 or 45 degrees is optimal for decreasing intracranial pressure. Research about the relationship of position changes and the outcomes of patient primary diseases is absent. © 2015 John Wiley & Sons Ltd.

  11. Pressure drop in packed beds of spherical particles at ambient and elevated air temperatures

    Directory of Open Access Journals (Sweden)

    Pešić Radojica

    2015-01-01

    Full Text Available The aim of this work was the experimental investigation of the particle friction factor for air flow through packed bed of particles at ambient and elevated temperatures. The experiments were performed by measuring the pressure drop across the packed bed, heated to the desired temperature by hot air. Glass spherical particles of seven different diameters were used. The temperature range of the air flowing through the packed bed was from 20ºC to 350ºC and the bed voidages were from 0.3574 to 0.4303. The obtained results were correlated using a number of available literature correlations. The overall best fit of all of the experimental data was obtained using Ergun [1] equation, with mean absolute deviation of 10.90%. Ergun`s equation gave somewhat better results in correlating the data at ambient temperature with mean absolute deviation of 9.77%, while correlation of the data at elevated temperatures gave mean absolute deviation of 12.38%. The vast majority of the correlations used gave better results when applied to ambient temperature data than to the data at elevated temperatures. Based on the results obtained, Ergun [1] equation is proposed for friction factor calculation both at ambient and at elevated temperatures. [Projekat Ministarstva nauke Republike Srbije, br. ON172022

  12. Posterior reversible encephalopathy syndrome following elevated mean arterial pressures for cervical spinal cord injury.

    Science.gov (United States)

    Zimering, Jeffrey H; Mesfin, Addisu

    2018-01-01

    Increasing the mean arterial pressure (MAP) is an accepted treatment modality to minimize the risk for irreversible neurologic damage secondary to spinal cord ischemia. Posterior reversible encephalopathy syndrome (PRES) is a rare complication occurring after transplantation surgery, in persons having an autoimmune disorder or after abrupt increases in blood pressure of various etiologies. Case report. Retrospective evaluation of medical records. A 68-year-old female with long-standing diabetes, and rheumatoid arthritis (treated with methotrexate) presented with bilateral upper extremity weakness and numbness developing several days after a motor vehicle accident. Physical examination confirmed decreased upper extremity motor strength and decreased sensation to light touch and pinprick in the C5-C6 dermatomal distribution. Magnetic resonance imaging (MRI) demonstrated C5-C6 subluxation with spinal cord compression. The patient had traction applied and mean arterial pressures were elevated greater than 85 mmg. The following day the patient underwent anterior and posterior cervical spine fusion and decompression. Immediately post-operatively, the patient developed status epilepticus. Head MRI revealed areas of high T2 signal intensity in the bilateral occipital lobes, consistent with a diagnosis of PRES. Two weeks later, the patient had resolution of her symptoms and resolution of PRES on imaging. This is the first report of posterior reversible encephalopathy syndrome secondary to therapeutic blood pressure increase in the setting of cervical spine fracture with neurological deficits. The patients had resolution of symptoms following discontinuation of the MAP goals. Posterior reversible encephalopathy syndrome (PRES) is a life-threatening condition characterized by seizures, confusion, visual disturbance, and headaches alongside neuroradiological findings indicative of posterior cerebral hemispheric white matter edema. 1,2 PRES has been described in association

  13. Equilibrium moisture content of radiata pine at elevated temperature and pressure reveals measurement challenges

    DEFF Research Database (Denmark)

    Pearson, Hamish; Gabbitas, Brian; Ormarsson, Sigurdur

    2012-01-01

    moisture contents were attributed to condensation of liquid water on the specimen with subsequent evaporation at a rate that was too slow for the moisture content to reach equilibrium before it was measured. Reliable EMC data at elevated temperatures require (1) tight process control of experimental......Relatively few studies have been performed on the equilibrium moisture content (EMC) of wood under conditions of elevated temperature and pressure. Eight studies indicated that EMC near saturation decreased between 100 and 150 °C, whilst five studies indicated that EMC increased. The aim...... of this study was to identify the likely source of the disagreement using radiata pine (Pinus radiata D. Don) sapwood which was conditioned to a moisture content of around 3 % and then exposed for 1 h at 150 °C and relative humidities of either 50, 70 or 90 %. Mean values of EMC, obtained through in situ...

  14. Evidence of a hyperkinetic state in children with elevated blood pressure.

    Science.gov (United States)

    Chirico, Daniele; Wade, Terrance J; Cairney, John; Klentrou, Panagiota; O'Leary, Deborah D

    2015-01-01

    Left ventricular hypertrophy (LVH) and elevated left ventricular mass index (LVMI) are important predictors of cardiovascular morbidity and mortality in adults. Children with hypertension and pre-hypertension demonstrate LVH and greater LVMI compared to normotensive children. The impact of blood pressure (BP) on early changes in left ventricular properties provides an opportunity to understand and identify cardiovascular risk early in childhood. The aim of this study was to assess left ventricular structural and functional properties in a sample of children across a wide range of BP values. Children aged 11-14-years were divided into BP groups: hypertensives (HTN; ≥95th percentile; n = 21) and normotensives (NTN; index were found to be independent predictors of BP group status in children. These findings show that children with elevated BP are characterized by high HR and CO and normal TPR. Also, the results identify HR as a predictor of BP group status in early childhood.

  15. [Laser flash photolysis, EPR and Raman studies of liquids at elevated pressures

    Energy Technology Data Exchange (ETDEWEB)

    Eyring, E.M.

    1992-01-01

    The proposed research will solve a number of analytical chemical problems in solutions with measurement techniques that benefit from the use of elevated hydrostatic pressures: stopped-flow spectrophotometry (Gd[sup 3+] + L(ligand), [RuL[sub 5]H[sub 2]O][sup 2+], laser flash photolysis of Mo(CO)[sub 6] + L, flash photolysis of binuclear metalloproteins), EPR spectroscopy (Gd[sup 3+] ion-exchanged into ETS-10 and ETAS-10 molecular sieves), laser flash photolysis kinetic studies of Mo(CO)[sub 6]-2,2'-bipyridine, and electrochemical studies of metalloporphyrins using resonance Raman spectroscopy.

  16. [Laser flash photolysis, EPR and Raman studies of liquids at elevated pressures

    Energy Technology Data Exchange (ETDEWEB)

    Eyring, E.M.

    1992-10-01

    The proposed research will solve a number of analytical chemical problems in solutions with measurement techniques that benefit from the use of elevated hydrostatic pressures: stopped-flow spectrophotometry (Gd{sup 3+} + L(ligand), [RuL{sub 5}H{sub 2}O]{sup 2+}, laser flash photolysis of Mo(CO){sub 6} + L, flash photolysis of binuclear metalloproteins), EPR spectroscopy (Gd{sup 3+} ion-exchanged into ETS-10 and ETAS-10 molecular sieves), laser flash photolysis kinetic studies of Mo(CO){sub 6}-2,2`-bipyridine, and electrochemical studies of metalloporphyrins using resonance Raman spectroscopy.

  17. Two kinds of urinary continence reflexes during abrupt elevation of intravesical pressure in rats.

    Science.gov (United States)

    Kamo, Izumi; Kaiho, Yasuhiro; Miyazato, Minoru; Torimoto, Kazumasa; Yoshimura, Naoki

    2009-09-01

    Urethral closure mechanisms during abrupt elevation of intravesical pressure (P(ves)) were investigated. During sneezing, the middle urethral closing response was observed and it still remained after opening the abdomen. The middle urethral response was almost completely abolished after bilateral transection of somatic nerves innervating the external urethral sphincter and the pelvic floor muscles, while bilateral transection of both pelvic nerves and hypogastric nerves had no effects. Somatic nerve transection resulted in fluid leakage from the urethral orifice during sneezing. Passive increments of P(ves) for 120 seconds by elevating a saline reservoir connected to the bladder also induced the middle urethral closing response in rats with spinal cord transection at T8-T9. The response was totally abolished by cutting pelvic nerves bilaterally, and partially reduced after bilateral transection of pudendal nerves, nerves to pelvic floor muscles or hypogastric nerves. Electrical stimulation of abdominal muscles (ESAM) for 1 second elevated P(ves) in a stimulus-dependent manner in the spinal cord-transected rats, and the P(ves) rise was almost lost when the abdomen was opened. The P(ves) inducing fluid leakage from the urethral orifice was lowered in rats when pelvic nerves or somatic nerves were cut bilaterally, while transection of bilateral hypogastric nerves showed smaller effects. These results indicate that at least two kinds of urinary continence reflexes close the middle urethra during abrupt elevation of P(ves); one reflex observed during sneeze is preprogrammed so as to close the urethra automatically irrespective of bladder afferent activity, and the other reflex is triggered by bladder afferent excitation. During momentary stress events such as sneezing (elevation for 120 seconds, both striated and smooth muscles are involved in the prevention of stress urinary incontinence.

  18. Additive pressures of elevated sea surface temperatures and herbicides on symbiont-bearing foraminifera.

    Directory of Open Access Journals (Sweden)

    Joost W van Dam

    Full Text Available Elevated ocean temperatures and agrochemical pollution individually threaten inshore coral reefs, but these pressures are likely to occur simultaneously. Experiments were conducted to evaluate the combined effects of elevated temperature and the photosystem II (PSII inhibiting herbicide diuron on several types of symbiotic algae (diatom, dinoflagellate or rhodophyte of benthic foraminifera in hospite. Diuron was shown to evoke a direct effect on photosynthetic efficiency (reduced effective PSII quantum yield ΔF/F'(m, while elevated temperatures (>30 °C, only 2 °C above current average summer temperatures were observed to impact photosynthesis more indirectly by causing reductions in maximum PSII quantum yield (F(v/F(m, interpreted as photodamage. Additionally, elevated temperatures were shown to cause bleaching through loss of chlorophyll a in foraminifera hosting either diatoms or dinoflagellates. A significant linear correlation was found between reduced F(v/F(m and loss of chlorophyll a. In most cases, symbionts within foraminifera proved more sensitive to thermal stress in the presence of diuron (≥ 1 µg L(-1. The mixture toxicity model of Independent Action (IA described the combined effects of temperature and diuron on the photosystem of species hosting diatoms or dinoflagellates convincingly and in agreement with probabilistic statistics, so a response additive joint action can be assumed. We thus demonstrate that improving water quality can improve resilience of symbiotic phototrophs to projected increases in ocean temperatures. As IA described the observed combined effects from elevated temperature and diuron stress it may therefore be employed for prediction of untested mixtures and for assessing the efficacy of management measures.

  19. Additive pressures of elevated sea surface temperatures and herbicides on symbiont-bearing foraminifera.

    Science.gov (United States)

    van Dam, Joost W; Negri, Andrew P; Mueller, Jochen F; Altenburger, Rolf; Uthicke, Sven

    2012-01-01

    Elevated ocean temperatures and agrochemical pollution individually threaten inshore coral reefs, but these pressures are likely to occur simultaneously. Experiments were conducted to evaluate the combined effects of elevated temperature and the photosystem II (PSII) inhibiting herbicide diuron on several types of symbiotic algae (diatom, dinoflagellate or rhodophyte) of benthic foraminifera in hospite. Diuron was shown to evoke a direct effect on photosynthetic efficiency (reduced effective PSII quantum yield ΔF/F'(m)), while elevated temperatures (>30 °C, only 2 °C above current average summer temperatures) were observed to impact photosynthesis more indirectly by causing reductions in maximum PSII quantum yield (F(v)/F(m)), interpreted as photodamage. Additionally, elevated temperatures were shown to cause bleaching through loss of chlorophyll a in foraminifera hosting either diatoms or dinoflagellates. A significant linear correlation was found between reduced F(v)/F(m) and loss of chlorophyll a. In most cases, symbionts within foraminifera proved more sensitive to thermal stress in the presence of diuron (≥ 1 µg L(-1)). The mixture toxicity model of Independent Action (IA) described the combined effects of temperature and diuron on the photosystem of species hosting diatoms or dinoflagellates convincingly and in agreement with probabilistic statistics, so a response additive joint action can be assumed. We thus demonstrate that improving water quality can improve resilience of symbiotic phototrophs to projected increases in ocean temperatures. As IA described the observed combined effects from elevated temperature and diuron stress it may therefore be employed for prediction of untested mixtures and for assessing the efficacy of management measures.

  20. A comparison of intraocular pressure values obtained with the Tono-Pachymeter NT530P, iCare® rebound tonometer and Goldmann applanation tonometer

    Directory of Open Access Journals (Sweden)

    N. Rampersad

    2011-12-01

    Full Text Available The purpose of this study was to compare the intraocular pressure (IOP values measured with the Tono-Pachymeter NT530P (Tonopachy™ and the iCare® rebound tonometer (iCare® with those obtained by the Goldmann applanation tonometer (GAT. The right eyes of 105 subjects aged 18 to 82 years (mean age = 29.27 ± 14.67 years were assessed with the three tonometers. Central corneal thickness (CCT was measured first using the Tonopachy™ and then IOP was measured by Tonopachy™, iCare® and GAT. The data was analyzed with descriptive statistics, paired  t-test, correlation and regression analysis. The Bland-Altman method of analysis was used to evaluate agreements between the sets of data from the three devices. The CCT values ranged from 440 µm to 606 µm (mean= 518.49 ± 33.01 µm. There was little or no correlation between CCT and IOP for any of the instruments used in this study (r = 0.29 for Tonopachy™, r = 0.22 for iCare®, r = 0.17 for GAT. The mean IOP measured with the Tonopachy™ was 14.31 ± 3.57 mmHg (range 8.7 mmHg to 31 mmHg and 16.64 ± 4.38 mmHg (range 8 mmHg to 32 mmHg using the iCare®. The mean IOP measured with the GAT was 14.79 ± 3.09 mmHg (range 8.7 mmHg to 29.7 mmHg. Using the Bland-Altman method, the upper and lower limits of agreement between the Tonopachy™ and GAT, iCare® and GAT, iCare® and Tonopachy™ were 5.1 mmHg and –4.2 mmHg, 8.6 mmHg and –4.9 mmHg, 7.5 mmHg and –2.8 mmHg respectively. In 79.1% of the eyes studied, the mean IOP difference between Tonopachy™ and GAT was less than 3 mmHg and in 20.9% of the eyes, the difference was greater than 3 mmHg. However, mean IOP differences of greater than 3 mmHg were obtained by iCare® in comparison with GAT (40% and Tonopachy™ (34.3% respectively. Findings of this study suggest that the Tonopachy™ yielded IOP readings that were consistent with those of GAT values while iCare® yielded higher IOP values compared to both GAT and Tonopachy™. (S Afr

  1. The Upper Limit of Cerebral Blood Flow Autoregulation Is Decreased with Elevations in Intracranial Pressure.

    Science.gov (United States)

    Pesek, Matthew; Kibler, Kathleen; Easley, R Blaine; Mytar, Jennifer; Rhee, Christopher; Andropolous, Dean; Brady, Ken

    2016-01-01

    The upper limit of cerebrovascular pressure autoregulation (ULA) is inadequately characterized. We sought to delineate the ULA in a neonatal swine model. Neonatal piglets with sham surgery (n = 9), interventricular fluid infusion (INF; n = 10), controlled cortical impact (CCI; n = 10), or impact + infusion (CCI + INF; n = 11) had intracranial pressure monitoring and bilateral cortical laser-Doppler flux recordings during arterial hypertension until lethality. An increase in red cell flux as a function of cerebral perfusion pressure was determined by piecewise linear regression and static rates of autoregulation (SRoRs) were determined above and below this inflection. When identified, the ULA (median [interquartile range]) was as follows: sham group: 102 mmHg (97-109), INF group: 75 mmHg (52-84), CCI group: 81 mmHg (69-101), and CCI + INF group: 61 mmHg (52-57; p = 0.01). Both groups with interventricular infusion had significantly lower ULA compared with the sham group. Neonatal piglets without intracranial pathological conditions tolerated acute hypertension, with minimal perturbation of cerebral blood flow. Piglets with acutely elevated intracranial pressure, with or without trauma, demonstrated loss of autoregulation when subjected to arterial hypertension.

  2. Apelin elevates blood pressure in ICR mice with L-NAME-induced endothelial dysfunction

    Science.gov (United States)

    NAGANO, KATSUMASA; ISHIDA, JUNJI; UNNO, MADOKA; MATSUKURA, TANOMU; FUKAMIZU, AKIYOSHI

    2013-01-01

    Apelin is the endogenous ligand of APJ, which belongs to the family of G protein-coupled receptors. Apelin and APJ are highly expressed in various cardiovascular tissues, including the heart, kidney and vascular endothelial and smooth muscle cells. Although apelin exerts hypotensive effects via activation of endothelial nitric oxide synthase (eNOS), the ability of apelin to regulate blood pressure under pathological conditions is poorly understood. In the current study, NG-nitro-L-arginine methyl ester (L-NAME), a potent NOS inhibitor, was administered chronically, to induce peripheral vascular damage in mice. L-NAME-treated mice exhibited hypertension, increased vascular cell adhesion molecule-1 and plasminogen activator inhibitor-1 mRNA levels in the aorta and impaired vasodilatation associated with decreased aortic eNOS expression, consistent with endothelial damage. Three days following withdrawal of L-NAME treatment, the blood pressure response to apelin stimulation was assessed. Although apelin reduced blood pressure in non-treated mice, it was found to transiently elevate blood pressure in L-NAME-treated mice. These results indicate that apelin functions as a vasopressor peptide under pathological conditions, including vascular endothelial dysfunction in mice. PMID:23525196

  3. Effect of renal venous pressure elevation on tubular sodium and water reabsorption in the dog kidney

    DEFF Research Database (Denmark)

    Abildgaard, U; Amtorp, O; Holstein-Rathlou, N H

    1988-01-01

    This study was performed in order to quantify the effects of renal venous pressure (RVP) elevation on absolute and fractional reabsorption rates of sodium and water in proximal and distal segments of the nephron in dog kidneys. Renal blood flow (RBF) was measured electromagnetically. Clearance...... unaffected by acute surgical denervation of the kidneys. In contrast, chronic renal denervation or infusion of phentolamine (5 micrograms kg-1 min-1) into the renal artery eliminated the increase in APR and FPR during RVP elevation to 20 mmHg. Chronic, but not acute renal denervation depleted renal tissue...... of the nephron. In the kidneys with intact innervation RVP elevation to 19.9 +/- 0.1 mmHg caused significant increases in both absolute (APR) and fractional (FPR) proximal reabsorption rates from 33.4 +/- 4.2 to 38.7 +/- 2.0 ml min-1 and from 0.62 +/- 0.04 to 0.71 +/- 0.04, respectively. These responses were...

  4. Extreme Tolerance to Elevated Pressure in a Thermococcus isolate from the Mid-Cayman Rise

    Science.gov (United States)

    Narasingarao, P.; Huber, J. A.; Schrenk, M. O.; Bartlett, D.

    2013-12-01

    Hydrothermal systems are windows into the deep biosphere. Venting fluids with temperatures up to 400°C containing gases such as H2, CO2, H2S and CH4 provide an oasis of life in the deep ocean primarily based on chemosynthesis. The Mid-Cayman Rise (MCR) includes the deepest hydrothermal vent system known thus far, and is characterized by two venting sites Piccard (4950m) and Von Damm (2350m). Here we demonstrate the remarkable high pressure tolerance limits of a Thermococcus sp. designated strain 175, isolated from samples collected from Piccard during an expedition in 2012. Diffuse venting fluids collected at the site resulted in the isolation of several Thermococcus strains capable of growth in basal salts medium supplemented with H2/CO2 and yeast extract, along with sulfur as an electron acceptor. Given the importance of pressure as an environmental parameter influencing evolution and adaptation of deep-sea life, the pressure tolerance of Thermococcus strain 175 was tested. High pressure incubations were originally conducted in serum vials filled completely with growth medium and therefore lacking all headspace gas. To test for growth with H2/CO2 , modified hungate tubes with a piston mechanism were used (Bowles et al. 2011) . The results indicate that strain 175 can grow at 90°C up to 120 megapascal (MPa). Growth rates are comparable when the strain is grown at atmospheric pressure or at 120 MPa pressure. Morphologically, the strain is irregular cocci and does not show any changes in its cellular structure when switched between atmospheric pressure and elevated pressure. This wide range of pressure tolerance has not been previously observed in other microorganisms, including Pyrococcus yayanosii CH1 (Zeng et al., 2009) which is also capable of growth at 120MPa but does not grow below 15 MPa. Thermococcus strain 175 represents an excellent model system to study high pressure adaptation due to its high growth rate and broad range of growth pressures. The

  5. Childhood obesity and elevated blood pressure in a rural population of northern Greece.

    Science.gov (United States)

    Mavrakanas, Thomas A; Konsoula, Georgia; Patsonis, Ioannis; Merkouris, Bodossakis P

    2009-01-01

    The objective of this study was to determine the prevalence of childhood obesity and elevated blood pressure (BP) in a rural population of northern Greece. In total, 572 schoolchildren between the age of 4 and 10 years were examined. Obesity was defined using three different standards: (1) body mass index (BMI) charts of the French socie