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Sample records for white-to-white corneal diameter

  1. Use of a novel lamellar keratoplasty with pleat technique to address the abnormal white-to-white diameter in keratoglobus.

    Science.gov (United States)

    Lockington, David; Ramaesh, Kanna

    2015-02-01

    We describe a novel surgical technique that seeks to address the fundamental mechanical problem of the superiorly and vertically displaced limbus and the corresponding abnormal corneal white-to-white diameter in keratoglobus. A 42-year-old woman had progressive reduction of vision due to hydrops of her right cornea with secondary peripheral corneal perforation due to progressive bilateral keratoglobus. Her visual acuity was hand movements in the right eye, with an uncorrectable refractive error. Pachymetry ranged from 287 μm in the peripheries to 474 μm centrally. The simulated keratometry average was 87 diopters. The surgical technique includes corneal debridement, paracentesis to facilitate manipulation of the cornea, cardinal compression sutures, central anterior lamellar dissection, and mattress sutures to tuck the excess peripheral cornea to create a pleat. This intralamellar tuck formed the subsequent bed to host an anterior lamellar corneal graft. At 1-year review, the best-corrected visual acuity was 6/24 (-2.50/+2.00 ×75 in the right eye). Central corneal pachymetry was 744 μM in the right eye. The simulated keratometry average was 42.4 diopters. This visual improvement and refraction remained stable for 3 years postoperatively. We have demonstrated a modified anterior lamellar keratoplasty with pleat technique to achieve satisfactory visual rehabilitation in extreme keratoglobus. This pleat technique addresses the fundamental structural problem of a vertically displaced limbus in keratoglobus. We highlight the optical illusion of the white-to-white diameter in keratoglobus. We also recommend the baking analogy of muffin to cupcake as a communication aid when explaining the mechanics of surgery to the patient.

  2. Comparison of postoperative vault height predictability using white-to-white or sulcus diameter-based sizing for the visian implantable collamer lens.

    Science.gov (United States)

    Reinstein, Dan Z; Lovisolo, Carlo F; Archer, Timothy J; Gobbe, Marine

    2013-01-01

    To compare vault height predictability of Implantable Collamer Lens (ICL; Staar Surgical) sizing using a sulcus diameter-based formula or the manufacturer-recommended white-to-white-based method. In 50 myopic eyes, ICL size was calculated using both a formula including sulcus diameter and the traditional formula based on white-to-white diameter. Sulcus diameter was measured using Artemis 2 very high-frequency (VHF) digital ultrasound (ArcScan Inc). Implantation was based on the sulcus diameter derived size. Actual postoperative vault height achieved was measured by VHF digital ultrasound scanning. Circle segment trigonometry was used to calculate the vault height that would have resulted had lens sizing been based on the white-to-white formula. The same lens size would have been used in 60% of eyes, a smaller lens would have been used in 34% of eyes and a larger lens in 6% of eyes had lens sizing been based on the white-to-white formula. Mean vault for eyes with lenses sized using the sulcus diameter formula was 0.37±0.16 mm (range: 0.08 to 0.92 mm), with 2% trigonometry predicted that the vault height would have been 0.24±0.28 mm (range: -0.31 to 0.92 mm), with 26% <0.09 mm had lens sizing been based on the white-to-white formula. Significantly better predictability of postoperative vault height was achieved by including sulcus diameter into the ICL sizing formula compared with using the traditional white-to-white-based formula. Copyright 2013, SLACK Incorporated.

  3. Measurements of anterior chamber depth, white-to-white distance, anterior chamber angle, and pupil diameter using two Scheimpflug imaging devices

    Directory of Open Access Journals (Sweden)

    Alberto Domínguez-Vicent

    2014-08-01

    Full Text Available Purpose: To compare the ocular anterior chamber depth, white-to-white distance, anterior chamber angle, and pupil diameter, as measured with two different Scheimpflug imaging devices. Methods: This transversal study included 80 right eyes from 80 subjects aged from 20 to 40 years. Their spherical equivalents ranged from -4.25 to +1.00 diopters (D. Each eye's anterior chamber depth, white-to-white distance, anterior chamber angle, and pupil diameter, were measured for far vision using both the Galilei G4 (double Scheimpflug camera and the Pentacam HR (single Scheimpflug camera systems. Results: Mean anterior chamber depths were calculated as 3.12 ± 0.23 mm and 3.19 ± 0.24 mm when measured with the Galilei G4 and the Pentacam HR, respectively. The mean white-to-white distance measured was 11.84 ± 0.31 mm and 11.90 ± 0.43 mm when measured with the Galilei G4 and the Pentacam HR, respectively. Mean pupil diameters were measured as 3.22 ± 0.58 mm and 3.22 ± 0.52 mm when measured with the Galilei G4 and the Pentacam HR, respectively. Finally, the mean anterior chamber angle was 34.30 ± 2.86 degrees when it was measured with the Galilei G4, and 39.26 ± 2.85 degrees when measured with the Pentacam HR. A comparative analysis revealed that the Galilei G4 yielded a significantly lower (P0.05 for both devices were obtained for the white-to-white distance measurements. Conclusion: The Galilei G4 and Pentacam HR Scheimpflug systems cannot be used interchangeably because they produce significant measurement differences.

  4. Analysis of the horizontal corneal diameter, central corneal thickness, and axial length in premature infants

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    Ozdemir Ozdemir

    2014-08-01

    Full Text Available Purpose: To determine the horizontal corneal diameter, central corneal thickness, and axial length in premature infants. Methods: Infants with a birth weight of less than 2,500 g or with a gestation period of less than 36 weeks were included in the study. Infants with retinopathy of prematurity (ROP were allocated to Group 1 (n=138, while those without ROP were allocated to Group 2 (n=236. All infants underwent a complete ophthalmologic examination, including corneal diameter measurements, pachymetry, biometry, and fundoscopy. Between-group comparisons of horizontal corneal diameter, central corneal thickness, and axial lengths were performed. Independent sample t-tests were used for statistical analysis. Results: Data was obtained from 374 eyes of 187 infants (102 female, 85 male. The mean gestational age at birth was 30.7 ± 2.7 weeks (range 25-36 weeks, the mean birth weight was 1,514 ± 533.3 g (range 750-1,970 g, and the mean postmenstrual age at examination was 40.0 ± 4.8 weeks. The mean gestational age and the mean birth weight of Group 1 were statistically lower than Group 2 (p0.05. Conclusions: The presence of ROP in premature infants does not alter the horizontal corneal diameter, central corneal thickness, or axial length.

  5. Corneal diameters in infants born in two hospitals in Ibadan, Nigeria ...

    African Journals Online (AJOL)

    Objectives: To measure the horizontal corneal diameters in infants at birth and compare with values reported in other studies. Design: A cross-sectional hospital based study. Subjects: All the healthy infants born within the period of one month in these hospitals were eligible for enrolment into the study. Horizontal corneal ...

  6. A review of corneal diameter, curvature and thickness values and influencing factors*

    Directory of Open Access Journals (Sweden)

    K. P. Mashige

    2013-12-01

    Full Text Available The cornea is an important ocular structure involved in the mediation of visual perception. It is the principal refractive surface of the eye and vision can be significantly affected by relatively small changes in its structure and parameters. Measurement of corneal parameters is important in the diagnosis and management of ocular diseasessuch as keratoconus and glaucoma, and also in the fitting of contact lenses or with refractive surgery such as Laser-Assisted in situ Keratomileusis(LASIK and photorefractive keratectomy (PRK. The human corneal diameter, anterior curvature and centre thickness as well as factors influencing them are reviewed in this article. This review will be useful to eye care professionals who routinely measure these parameters when fitting contact lenses and assessing, diagnosing as well as managing corneal and other ocular conditions. (S Afr Optom 2013 72(4 185-194

  7. [Effect of optical zone diameter on corneal biomechanical properties after small incision lenticule extraction].

    Science.gov (United States)

    Wei, P H; Wang, Y; Li, H; Dou, R; Li, L Y; Zhao, W; Zhang, J M

    2017-03-11

    Objective: To investigate the effect of optical zone diameter on corneal biomechanical properties after small incision lenticule extraction (SMILE). Methods: In this prospective case-control study, 62 eyes of 42 patients with myopia and myopic astigmatism that had undergone SMILE procedure were divided into 2 groups according to the optical zone (OZ) diameter: group A, 31 eyes of 19 patients, OZ= 6.5 mm; group B, 31eyes of 23 patients, OZ=6.0 mm. These patients were examined for corneal hysteresis (CH) and corneal resistance factor (CRF) with the Ocular Response Analyzer (ORA) preoperatively and at 1 week, 1 month and 3 months postoperatively; at the same time, the central corneal thickness-corrected indices of DifCH and DifCRF were calculated. Pearson correlation was applied to analyze the correlation between CH and CRF and central corneal thickness. Independent-samples t test was utilized to compare CH and CRF between the two groups. Repeated ANOVA was used to compare the difference of corneal biomechanical properties at different follow-up timepoints. Results: The preoperative mean CRF and CH values were (10.13±1.19) mmHg and (9.65±1.12) mmHg in group A and (10.34±0.89) mmHg and (10.04± 1.05) mmHg in group B, respectively, and no significant differences were found in CRF and CH between the two groups (CRF: t=-0.807, P=0.423. CH: t=-1.405, P=0.165). The mean CRF values in group A at postoperative 1 week and 3 months were (6.62 ± 1.09) mmHg and (6.83 ± 1.07) mmHg, respectively, which were significantly lower than the relevant mean CRF values in group B (t=-2.703, P=0.009. t=-3.733, P= 0.001). Meanwhile, the mean CH values at 1 week, 1 month and 3 months postoperatively in group A were (7.31±1.06) mmHg, (7.37±0.96) mmHg and (7.82±0.97) mmHg, respectively, which were significantly lower than those in group B (t=-2.415, P=0.019. t=-2.113, P=0.039. t=-2.67, P=0.01). Moreover, the DifCRF and DifCH values in group A were significantly lower than those in group

  8. [The effects of cycloplegic eyedrops on corneal tomography].

    Science.gov (United States)

    Kalezic, T; Vukovic, I; Andjelkovic, M; Gajic, M; Potic, J; Stojkovic, M

    2016-12-01

    Whether cycloplegics affect standard keratorefractometric and tomographic measurements is unknown. The purpose of our study was to compare the effects of cycloplegics (cyclopentolate and atropine) on corneal shape and refractive power of the eye. This study was performed on 84 eyes of 49 study participants. Patients were randomized into two groups: atropine 1% (32 eyes) and cyclopentolate 1% (52 eyes). Corneal tomography was performed with the Orbscan IIz. To evaluate the corneal shape, simulated keratometry values, anterior and posterior best-fit sphere, white-to-white and tangential and axial corneal power were performed for the anterior and posterior corneal surfaces before and during cycloplegia. Pupil diameter, anterior chamber depth, corneal thickness at the 3, 5 and 7mm optical zones, thinnest area of the cornea and corneal thickness at the visual axis were examined. Data were analyzed using an SPSS statistical package. The anterior and posterior BFS (in the atropine 1% group, anterior BFS was P=0.188; anterior BFS in the cyclopentolate group was P=0.227) and tangential and axial corneal power showed no change during cycloplegia in either group. SimK showed no statistical significance. The ACD was deeper when using atropine than cyclopentolate. Corneal thickness remained unchanged during cycloplegia in both groups. Pupil diameter was larger in light-colored irides in the cyclopentolate group than the atropine group. There was no change in W to W before (P=0.473) and during cycloplegia (P=0.287) in either group. Our results suggest that usage of atropine or cyclopentolate does not alter corneal shape. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  9. Visual outcomes and safety of a small diameter intrastromal refractive inlay for the corneal compensation of presbyopia.

    Science.gov (United States)

    Bouzoukis, Dimitrios I; Kymionis, George D; Panagopoulou, Sophia I; Diakonis, Vasilios F; Pallikaris, Aristophanes I; Limnopoulou, Aliki N; Portaliou, Dimitra M; Pallikaris, Ioannis G

    2012-03-01

    To investigate the outcomes and safety of an intrastromal refractive inlay (Invue Lens, Biovision AG) for the corneal compensation of presbyopia. This prospective, noncomparative, interventional clinical study comprised 45 emmetropic presbyopes with a mean age of 52.3 ± 3.3 years (range: 47 to 58 years). The refractive inlay was inserted in the non-dominant eye within a corneal pocket that was created using a mechanical microkeratome. Last follow-up was 12 months in all patients and examinations were scheduled at 1 week and 1, 3, 6, and 12 months after surgery. Visual, wavefront, contrast sensitivity, and topographic outcomes as well as structural corneal alteration were evaluated. Twelve months after surgery, uncorrected near visual acuity was 20/32 or better in 98% of operated eyes and binocularly, whereas uncorrected distance visual acuity was 20/40 or better in 93% of operated eyes and 20/25 or better in all patients binocularly. Three patients lost one line of corrected distance visual acuity in the operated eye. Overall, higher order aberrations were increased and contrast sensitivity was decreased in the operated eye. No tissue alterations were found using corneal confocal microscopy. No intra- or postoperative complications occurred. The intracorneal refractive inlay (Invue Lens) seems to be an effective surgical method for the corneal compensation of presbyopia in emmetropes aged between 45 and 60 years. Copyright 2012, SLACK Incorporated.

  10. Influence of eye biometrics and corneal micro-structure on noncontact tonometry.

    Directory of Open Access Journals (Sweden)

    Danilo A Jesus

    Full Text Available Tonometry is widely used as the main screening tool supporting glaucoma diagnosis. Still, its accuracy could be improved if full knowledge about the variation of the corneal biomechanical properties was available. In this study, Optical Coherence Tomography (OCT speckle statistics are used to infer the organisation of the corneal micro-structure and hence, to analyse its influence on intraocular pressure (IOP measurements.Fifty-six subjects were recruited for this prospective study. Macro and micro-structural corneal parameters as well as subject age were considered. Macro-structural analysis included the parameters that are associated with the ocular anatomy, such as central corneal thickness (CCT, corneal radius, axial length, anterior chamber depth and white-to-white corneal diameter. Micro-structural parameters which included OCT speckle statistics were related to the internal organisation of the corneal tissue and its physiological changes during lifetime. The corneal speckle obtained from OCT was modelled with the Generalised Gamma (GG distribution that is characterised with a scale parameter and two shape parameters.In macro-structure analysis, only CCT showed a statistically significant correlation with IOP (R2 = 0.25, p<0.001. The scale parameter and the ratio of the shape parameters of GG distribution showed statistically significant correlation with IOP (R2 = 0.19, p<0.001 and R2 = 0.17, p<0.001, respectively. For the studied group, a weak, although significant correlation was found between age and IOP (R2 = 0.053, p = 0.04. Forward stepwise regression showed that CCT and the scale parameter of the Generalised Gamma distribution can be combined in a regression model (R2 = 0.39, p<0.001 to study the role of the corneal structure on IOP.We show, for the first time, that corneal micro-structure influences the IOP measurements obtained from noncontact tonometry. OCT speckle statistics can be employed to learn about the corneal micro

  11. Corneal Laceration

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    Full Text Available ... What Is Corneal Laceration? Corneal Laceration Symptoms What Causes Corneal Laceration? Corneal Laceration Diagnosis Corneal Laceration Treatment ... the corneal laceration is deep enough it can cause a full thickness laceration. This is when the ...

  12. Corneal Laceration

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  13. Corneal collagens.

    Science.gov (United States)

    Robert, L; Legeais, J M; Robert, A M; Renard, G

    2001-05-01

    Cornea is a highly differentiated tissue rich in extracellular matrix (ECM) specifically distributed in space in order to insure its dual role--transparency and protection of inner eye-tissues. Corneal ECM is especially rich in collagens. Since the characterisation of a number of distinct collagen types it appeared that most of them are present in the cornea. Their synthesis follows a specific program of sequential expression of the different collagen types to be synthesised during the development and maturation of the cornea. The precise regulation of the diameter and orientation of fibers, and of the interfibrillar spaces is partially at least attributed to interactions between glycosaminoglycans and collagens. The 'program' of vectorial collagen synthesis and GAG-collagen interactions changes also with age and in several pathological conditions as corneal dystrophies and wound healing. The Maillard reaction, especially in diabetes, is one of these important factors involved in age-dependent modifications of corneal structure and function. Far from being inert, corneal collagens were shown to have relatively short half-lives. The biosynthesis of corneal collagens was studied also during wound healing. The refibrillation of wounded corneas does not follow the original 'program' of ECM-synthesis as shown by the comparative study of wound healing using biochemical and morphometric methods. This review recapitulates briefly previous and recent studies on corneal collagens in order to present to clinicians and scientists an overview of the state of the art of this important field at the intersection of eye research and matrix biology.

  14. Corneal Laceration

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    Full Text Available ... Corneal Laceration? Corneal Laceration Diagnosis Corneal Laceration Treatment What Is Corneal Laceration? Leer en Español: ¿Qué Es una Laceración de la Córnea? Written By: Daniel ...

  15. Corneal Ulcer

    Science.gov (United States)

    ... Español Eye Health / Eye Health A-Z Corneal Ulcer Sections What Is a Corneal Ulcer? Corneal Ulcer ... Diagnosis Corneal Ulcer Treatment What Is a Corneal Ulcer? Leer en Español: ¿Qué es una Úlcera de ...

  16. Ocular dimensions, corneal thickness, and corneal curvature in quarter horses with hereditary equine regional dermal asthenia.

    Science.gov (United States)

    Badial, Peres R; Cisneros-Àlvarez, Luis Emiliano; Brandão, Cláudia Valéria S; Ranzani, José Joaquim T; Tomaz, Mayana A R V; Machado, Vania M; Borges, Alexandre S

    2015-09-01

    The aim of this study was to compare ocular dimensions, corneal curvature, and corneal thickness between horses affected with hereditary equine regional dermal asthenia (HERDA) and unaffected horses. Five HERDA-affected quarter horses and five healthy control quarter horses were used. Schirmer's tear test, tonometry, and corneal diameter measurements were performed in both eyes of all horses prior to ophthalmologic examinations. Ultrasonic pachymetry was performed to measure the central, temporal, nasal, dorsal, and ventral corneal thicknesses in all horses. B-mode ultrasound scanning was performed on both eyes of each horse to determine the dimensions of the ocular structures and to calculate the corneal curvature. Each corneal region examined in this study was thinner in the affected group compared with the healthy control group. However, significant differences in corneal thickness were only observed for the central and dorsal regions. HERDA-affected horses exhibited significant increases in corneal curvature and corneal diameter compared with unaffected animals. The ophthalmologic examinations revealed mild corneal opacity in one eye of one affected horse and in both eyes of three affected horses. No significant between-group differences were observed for Schirmer's tear test, intraocular pressure, or ocular dimensions. Hereditary equine regional dermal asthenia-affected horses exhibit decreased corneal thickness in several regions of the cornea, increased corneal curvature, increased corneal diameter, and mild corneal opacity. Additional research is required to determine whether the increased corneal curvature significantly impacts the visual accuracy of horses with HERDA. © 2014 American College of Veterinary Ophthalmologists.

  17. Airbag-induced corneal flap.

    Science.gov (United States)

    Liyanage, Sidath E; Mearza, Ali A

    2009-02-01

    To describe a case of airbag-induced corneal flap in a previously normal cornea. Case report. A 27-year-old woman presented with complete loss of vision in her left eye following a road traffic accident which involved airbag deployment. There was no previous ocular history. Examination revealed a large corneal flap of 6mm in diameter, extending to the depth of anterior stroma. This was accompanied by a traumatic optic neuropathy. One month follow-up revealed complete reattachment of the corneal flap. This is the first reported case of a corneal flap induced by airbag deployment in a cornea with previously normal architecture.

  18. Corneal Laceration

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  19. Corneal Laceration

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  20. Corneal Laceration

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    Full Text Available ... Now that I’m older, will a corneal transplant help me? May 15, 2015 Why Do My ... May Have A Future Alternative to Full Corneal Transplantation Nov 29, 2016 Combating Eye Injuries from Air ...

  1. Corneal dystrophies

    Directory of Open Access Journals (Sweden)

    Klintworth Gordon K

    2009-02-01

    Full Text Available Abstract The term corneal dystrophy embraces a heterogenous group of bilateral genetically determined non-inflammatory corneal diseases that are restricted to the cornea. The designation is imprecise but remains in vogue because of its clinical value. Clinically, the corneal dystrophies can be divided into three groups based on the sole or predominant anatomical location of the abnormalities. Some affect primarily the corneal epithelium and its basement membrane or Bowman layer and the superficial corneal stroma (anterior corneal dystrophies, the corneal stroma (stromal corneal dystrophies, or Descemet membrane and the corneal endothelium (posterior corneal dystrophies. Most corneal dystrophies have no systemic manifestations and present with variable shaped corneal opacities in a clear or cloudy cornea and they affect visual acuity to different degrees. Corneal dystrophies may have a simple autosomal dominant, autosomal recessive or X-linked recessive Mendelian mode of inheritance. Different corneal dystrophies are caused by mutations in the CHST6, KRT3, KRT12, PIP5K3, SLC4A11, TACSTD2, TGFBI, and UBIAD1 genes. Knowledge about the responsible genetic mutations responsible for these disorders has led to a better understanding of their basic defect and to molecular tests for their precise diagnosis. Genes for other corneal dystrophies have been mapped to specific chromosomal loci, but have not yet been identified. As clinical manifestations widely vary with the different entities, corneal dystrophies should be suspected when corneal transparency is lost or corneal opacities occur spontaneously, particularly in both corneas, and especially in the presence of a positive family history or in the offspring of consanguineous parents. Main differential diagnoses include various causes of monoclonal gammopathy, lecithin-cholesterol-acyltransferase deficiency, Fabry disease, cystinosis, tyrosine transaminase deficiency, systemic lysosomal storage

  2. [Corneal biomechanics].

    Science.gov (United States)

    Torres, R M; Merayo-Lloves, J; Jaramillo, M A; Galvis, V

    2005-04-01

    To review the corneal biomechanic concepts and to analyse, clarify and understand their relevance in refractive surgery. A literature review has been done using different databases. Corneal biomechanic concepts are not new and are applied implicitly in numerous surgical procedures. Their origin is related to tonometry studies, but they gained in popularity when they were linked to the treatment of keratoconus, a pathology in which the mechanical properties of the cornea are altered. Factors determining corneal stability were thus defined. Corneal biomechanics have also been used following refractive surgery to study post-operative keratectasia and to improve ablation patterns, which ignores the corneal response. The new ablation systems need to include the biomechanical factors, which motivate research conducted in physical-mathematical models and in corneal wound healing, improving our knowledge about the corneal biomechanical response. The corneal biomechanic concepts have gained in popularity with the advent of refractive surgery, although they did exist previously. Their relevance is linked to improvements in the ablation systems used in an attempt to obtain more accurate and reliable results.

  3. Corneal Laceration

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    Full Text Available ... Answers How often and for how long should I use a hair dryer to treat my Fuchs’ dystrophy? May 06, 2017 I lost sight from a corneal scar as a child. Now that I’m older, will a corneal transplant help me? ...

  4. Corneal Laceration

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  5. Corneal Laceration

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  6. Corneal topography.

    Science.gov (United States)

    Seitz, B; Behrens, A; Langenbucher, A

    1997-08-01

    In the review period, limitations of individual Placido disk-based topography systems have been studied and new principles, such as raster photogrammetry, pancorneal slit topography, laser holographic interferometry, and confocal laser scanning topography, have been introduced for laboratory or clinical work. Both Fourier analysis and Zernike decomposition of topographic height data seem to be powerful new tools for cross-sectional analysis of complex topographic corneal images, such as after cataract surgery, penetrating keratoplasty, and refractive surgery, as well as for longitudinal studies of corneal changes, such as in schoolchildren. Subdividing into rational optical components may improve consistency and standardization of topography data from different systems. Topography-based flying-spot-mode excimer laser photoablation after Zernike decomposition of topography height data has been proposed for correction of irregular corneal astigmatism. Topography-based central power measurements are of increasing value for intraocular lens power calculation before cataract surgery in eyes with irregular corneal surfaces, such as in keratoconus or after refractive surgery procedures. Quantitative and qualitative classification of corneal topography maps after corneal transplantation following conventional mechanical and nonmechanical trephination or after refractive surgery may lead to a better understanding of impaired visual acuity despite a clear graft or despite significantly reduced ametropia or corneal astigmatism.

  7. Corneal Laceration

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  8. Corneal Laceration

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  9. Corneal Laceration

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  10. Corneal Laceration

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  11. Corneal Laceration

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  12. Corneal Laceration

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    Full Text Available ... By: Devin A Harrison MD Sep. 01, 2017 The cornea is the clear front window of the eye . A corneal laceration is a cut on the cornea. It is usually caused by something sharp ...

  13. Corneal Laceration

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  14. Corneal Laceration

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  16. Corneal Regeneration by Deep Anterior Lamellar Keratoplasty (DALK Using Decellularized Corneal Matrix.

    Directory of Open Access Journals (Sweden)

    Yoshihide Hashimoto

    Full Text Available The purpose of this study is to demonstrate the feasibility of DALK using a decellularized corneal matrix obtained by HHP methodology. Porcine corneas were hydrostatically pressurized at 980 MPa at 10°C for 10 minutes to destroy the cells, followed by washing with EGM-2 medium to remove the cell debris. The HHP-treated corneas were stained with H-E to assess the efficacy of decellularization. The decellularized corneal matrix of 300 μm thickness and 6.0 mm diameter was transplanted onto a 6.0 mm diameter keratectomy wound. The time course of regeneration on the decellularized corneal matrix was evaluated by haze grading score, fluorescein staining, and immunohistochemistry. H-E staining revealed that no cell nuclei were observed in the decellularized corneal matrix. The decellularized corneal matrices were opaque immediately after transplantation, but became completely transparent after 4 months. Fluorescein staining revealed that initial migration of epithelial cells over the grafts was slow, taking 3 months to completely cover the implant. Histological sections revealed that the implanted decellularized corneal matrix was completely integrated with the receptive rabbit cornea, and keratocytes infiltrated into the decellularized corneal matrix 6 months after transplantation. No inflammatory cells such as macrophages, or neovascularization, were observed during the implantation period. The decellularized corneal matrix improved corneal transparency, and remodelled the graft after being transplanted, demonstrating that the matrix obtained by HHP was a useful graft for corneal tissue regeneration.

  17. Corneal Transplantation

    DEFF Research Database (Denmark)

    Hjortdal, Jesper Østergaard

    Corneal transplantation has been performed for more than 100 years. Until 15 years ago the state-of-the art type of transplantation was penetrating keratoplasty, but since the start of this millennium, newly designed surgical techniques have developed considerably. Today, the vast majority...... with less risk of rejection episodes. Besides covering updated chapters on penetrating keratoplasty, and anterior and posterior lamellar procedures, this textbook also gives a thorough overview of the history of corneal transplantation and a detailed presentation of the microstructural components....... Economic considerations on cost and benefi t of medical treatment and surgical procedures are today an integrated part of the health system in many countries, and a chapter covers these aspects of corneal transplantation. This textbook is aimed at presenting an updated review of the new techniques...

  18. Biomechanical model of corneal transplantation.

    Science.gov (United States)

    Cabrera Fernández, D; Niazy, A M; Kurtz, R M; Djotyan, G P; Juhasz, T

    2006-03-01

    Refractive consequences of corneal transplants are analyzed using corneal biomechanical models assuming homogeneous and inhomogeneous stiffness distributions across the cornea. Additionally, refractive effects of grafts combined with volume removal procedures are also evaluated to develop methods to reduce postoperative refractive management of patients. Refinements of a two-dimensional finite element model are applied to simulate the biomechanical and refractive effects of different corneal transplant procedures: anterior lamellar keratoplasty, posterior lamellar keratoplasty, and penetrating keratoplasty. The models are based on a nonlinearly elastic, isotropic formulation. Predictions are compared with published clinical data. The model simulating the penetrating keratoplasty procedure predicts more change in the postoperative corneal curvature than models simulating anterior lamellar keratoplasty or posterior lamellar keratoplasty procedures. When a lenticle-shaped tissue with a central thickness of 50 microns and a diameter of 4 mm is removed from the anterior corneal surface along with the anterior lamellar keratoplasty or posterior lamellar keratoplasty, the models predict a refractive correction of -8.6 and -8.9 diopters, respectively. Simulations indicate that a posterior lamellar keratoplasty procedure is preferable for obtaining a better corneal curvature profile, eliminating the need for specific secondary treatments.

  19. Corneal Intelligence

    African Journals Online (AJOL)

    Murdoch3

    the damping effect of the tissue to an applied force) or corneal compliance being the major risk factor. Figure 1. The percentage of participants in the observation group who developed primary open-angle glaucoma (median follow-up, 72 months) ...

  20. Corneal ulcers

    African Journals Online (AJOL)

    visual acuity chart. • fluorescein strips. • topical anaesthetic eye drops. • direct ophthalmoscope. Examination. Assessing vision with a Snellen visual acuity chart gives a clue as to the extent of the problem (e.g. a corneal abrasion with good vision is unlikely to require specialist intervention). Each eye should be tested ...

  1. Corneal Intelligence

    African Journals Online (AJOL)

    Murdoch3

    Corneal Intelligence. Ian Murdoch. Institute of Ophthalmology, Bath Street, London. In 2002, the ocular hypertension treatment study (OHTS) published their results. This study had taken 1636 ocular hypertensives. 1, 2. (IOP 24-32mmHg) and randomized them to receive therapy or no therapy. The primary outcome of the ...

  2. Biosynthetic corneal implants for replacement of pathologic corneal tissue : performance in a controlled rabbit alkali burn model

    OpenAIRE

    Joanne M. Hackett; Lagali, Neil; Merrett, Kimberley; Edelhauser, Henry; Sun, Yifei; Gan, Lisha; Griffith, May; Fagerholm, Per

    2011-01-01

    Purpose: To evaluate the performance of structurally reinforced, stabilized recombinant human collagen-phosphorylcholine (RHCIII-MPC) hydrogels as corneal substitutes in a rabbit model of severe corneal damage. Methods: One eye each of 12 rabbits received a deep corneal alkali wound. Four corneas were implanted with RHCIII-MPC hydrogels. The other eight control corneas were implanted with either allografts or a simple crosslinked RHCIII hydrogel. In all cases, 6.25 mm diameter, 350 µm thick b...

  3. Corneal Transplantation in Children

    OpenAIRE

    Gabrić, N.; Dekaris, I.; Vojniković, B.; Karaman, Ž.; Mravičić, I.; Katušić, J.

    2001-01-01

    The main purpose of the study was to describe the surgical success rate and visual results of penetrating keratoplasty in children. This retrospective study included children that underwent corneal transplantation at the Department of Ophthalmology, General Hospital »Sveti Duh«, in the period 1994–1999. Patients’ age ranged from 6 to 16 years. Twenty-five corneal transplants were performed in 24 eyes. Corneal pathologies were corneal leucoma, congenital dystrophy, corneal combu...

  4. Influence of corneal astigmatism, corneal curvature and meridional differences on corneal hysteresis and corneal resistance factor.

    Science.gov (United States)

    Wong, Yin-zhi; Lam, Andrew K C

    2011-09-01

    This study investigated the influence of corneal astigmatism, corneal curvature and meridional differences on corneal hysteresis (CH) and the corneal resistance factor (CRF) in a group of normal Chinese persons. Ninety-five participants were recruited and data from the eye with higher corneal astigmatism were analysed. The anterior corneal curvature was measured by corneal topography. The Goldmann-correlated intraocular pressure (IOPg), corneal-compensated intraocular pressure (IOPcc), CH and CRF at different meridians (default horizontal position, 10°, 20° and 30° along the superotemporal and inferonasal meridians) were obtained from an ocular response analyser. The corneal powers at these specific meridians also were calculated. At the default position, the IOPg and CRF had weak correlations with corneal astigmatism, while the IOPcc and CH were not significantly correlated with corneal astigmatism. Both the IOPg and IOPcc were measured significantly higher at the default position. The CH and CRF were lower at the default position but the difference in the CRF from obliquity could not reach statistical significance. The CH was not significantly correlated with the corneal power at all meridians. The CRF correlated with the corneal power only at 30° superotemporal. Corneal astigmatism and head tilt did not have much effect on the measurement of CH and the CRF, both of which were lowest along the horizontal meridian. Clinically, the difference was small. The influence of corneal power on CH and the CRF was minimal. © 2011 The Authors. Clinical and Experimental Optometry © 2011 Optometrists Association Australia.

  5. Fibrin glue-assisted for the treatment of corneal perforationsusing glycerin-cryopreserved corneal tissue

    Directory of Open Access Journals (Sweden)

    Nuo Dong

    2014-04-01

    Full Text Available AIM: To evaluate the outcomes and safety of lamellar keratoplasty (LK assisted by fibrin glue in corneal perforations.METHODS: Six eyes of 6 patients affected by different corneal pathologies (2 posttraumatic corneal scar and 3 bacterial keratitis underwent LK procedures by using fibrin glue. The mean corneal perforation diameter was 1.35±0.64mm (range, 0.7-2.5mm, and the greatest diameter of the ulcerative stromal defect was 2.47±0.77mm in average (range, 1.5-3.5mm. The donor corneal lamella diameters were 0.20-mm larger and thicker than the recipient to restore a physiologic corneal thickness and shape:mean donor diameter was 8.34±0.28mm (range, 8.2-8.7mm and mean thickness was 352±40.27mm (range, 220-400mm. Mean follow-up was 7.33±1.97 months (range, 6-11 months. Postoperatively, the graft status, graft clarity, anterior chamber response, the visual prognosis, intraocular pressures, and postoperative complications were recorded.RESULTS: All the corneal perforations were successfully healed after the procedure. The best-corrected visual acuity (BCVA ranged from 20/1 000 to 20/50 in their initial presentation, and from 20/100 to 20/20 in their last visit, showed increase in all the patients. No major complications such as graft dislocation and graft failure were noted. Neovascularization developed in the superficial stroma of donor graft in 1 case. High intraocular pressure developed on day 2 after surgery, while was remained in normal range after application of anti-glaucomatous eyedrops for 1 week in 1 case.CONCLUSION: Fibrin glue-assisted sutureless LK is valuable for maintaining the ocular integrity in the treatment of corneal perforations.

  6. Surgical compensation of presbyopia with corneal inlays.

    Science.gov (United States)

    Konstantopoulos, Aris; Mehta, Jodhbir S

    2015-05-01

    Presbyopia, the physiological change in near vision that develops with ageing, gradually affects individuals older than 40 years and is a growing cause of visual disability due to ageing demographics of the global population. The routine use of computers and 'smartphones', combined with the affluence of the 'baby boomers' generation has set high standards for near vision correction. Corneal inlays are a relatively new treatment modality that is effective at compensating for presbyopia. The dimensions of these devices vary from 2 to 3.8 mm in diameter and 5 to 32 μm in thickness. They are implanted in the anterior corneal stroma of the non-dominant eye, most commonly, in a femtosecond laser created corneal pocket. They improve near vision by increasing the depth of focus, creating a hyper-prolate region of increased central cornea power or providing a refractive add power. This article reviews the literature on the efficacy and safety of corneal inlays.

  7. Study on the establishment of corneal alkali chemical injury on rats

    Directory of Open Access Journals (Sweden)

    Nan Hu

    2013-06-01

    Full Text Available AIM:To investigate the appropriate methods to establish corneal alkali chemical injury on rats. METHODS:The rats(n=87were randomly divided into three groups. Corneal alkali injury was induced by placing 1mol/L NaOH soaked filter paper on the limbus of right cornea for 20 seconds(group A, n=34or 40 seconds(group B, n=23, and on the central axis of the right cornea for 40 seconds(group C, n=30respectively. Corneal transparency, corneal ulceration, and corneal neovascularization were observed and recorded under slit- lamp biomicroscope on day 7 post-operation. RESULTS: Incidence of corneal ulceration, corneal perforation and positive rate of corneal fluorescein staining in limbal corneal injury groups(group A and Bwere significantly higher than that of central corneal injury group(group C(P<0.05. Incidence of corneal ulceration and corneal perforation in group B was significantly higher than group A(P<0.05. Corneal neovascularization was observed in all three groups. CONCLUSION: Corneal alkali burns induced by 3mm diameter central cornea injury are fit for the study of corneal neovascularization, while those induced by limbus injury for 20 seconds are fit for the study on limbal stem cells deficiency.

  8. Targeted corneal transplantation.

    Science.gov (United States)

    Jhanji, Vishal; Mehta, Jod S; Sharma, Namrata; Sharma, Bhavana; Vajpayee, Rasik B

    2012-07-01

    Corneal transplantation surgery has moved from an era of conventional penetrating keratoplasty to selective replacement of the diseased corneal layer with complementary healthy donor corneal tissue. Anterior lamellar transplantation surgeries do not involve replacement of corneal endothelium, consequently eliminating the occurrence of endothelial rejection. Similarly, in diseases affecting the corneal endothelium, selective replacement with a lamellar lenticule bearing healthy endothelium provides better outcomes in terms of ocular surface, lesser astigmatism and quick visual recovery. In addition to the advantages of enhanced surgical outcomes, targeted corneal transplantation allows the use of one donor cornea for more than one recipient, thereby offering a viable solution to the problem of paucity of donor corneas. Evolving techniques of corneal transplantation have enabled better utilization of donor corneal tissue. Anterior lamellar as well as endothelial keratoplasty surgeries have become first-choice surgeries in appropriately selected cases. This review briefly discusses some of these novel surgical techniques. A better understanding of targeted corneal transplantation would lead to adaptation of the concept of component corneal surgery. This would further enable the corneal surgeons to circumvent the problem of donor corneal shortage especially in the developing world.

  9. Equine corneal stromal abscesses

    DEFF Research Database (Denmark)

    Henriksen, M. D. L.; Andersen, P. H.; Plummer, C. E.

    2013-01-01

    The last 30 years have seen many changes in the understanding of the pathogenesis and treatment of equine corneal stromal abscesses (SAs). Stromal abscesses were previously considered an eye problem related to corneal bacterial infection, equine recurrent uveitis, corneal microtrauma and corneal...... foreign bodies in horses. They were more commonly diagnosed in horses living in subtropical climatic areas of the world. Therapeutic recommendations to treat equine SAs were historically nearly always a medical approach directed at bacteria and the often associated severe iridocyclitis. Today...... the pathogenesis of most equine SAs appears to be more often related to fungal inoculation of the anterior corneal stroma followed by posterior migration of the fungi deeper into the corneal stroma. There is also now an increased incidence of diagnosis of corneal SAs in horses living in more temperate climates...

  10. Corneal transplantation in children.

    Science.gov (United States)

    Gabrić, N; Dekaris, I; Vojniković, B; Karaman, Z; Mravicić, I; Katusić, J

    2001-01-01

    The main purpose of the study was to describe the surgical success rate and visual results of penetrating keratoplasty in children. This retrospective study included children that underwent corneal transplantation at the Department of Ophthalmology, General Hospital "Sveti Duh", in the period 1994-1999. Patients' age ranged from 6 to 16 years. Twenty-five corneal transplants were performed in 24 eyes. Corneal pathologies were corneal leucoma, congenital dystrophy, corneal combustion, corneal scar after perforating injury, keratoconus, corneal melting, hematocornea and rekeratoplasty. The follow-up period was at least 6 months. The rate of graft survival was 1 year in 75% of eyes with congenital dystrophy and keratoconus. Hematocornea and rekeratoplasty ended with graft failure. Postoperative visual acuity improvement was recorded in 14 out of 25 eyes. Penetrating keratoplasty in children showed very good surgical success. The final visual outcome was affected by irreversible amblyopia.

  11. Corneal topography and soft contact lens fit.

    Science.gov (United States)

    Young, Graeme; Schnider, Cristina; Hunt, Chris; Efron, Suzanne

    2010-05-01

    To determine which ocular topography variables affect soft contact lens fit. Fifty subjects each wore three pairs of soft lenses in random succession (Vistakon Acuvue 2, Vistakon Acuvue Advance, Ciba Vision Night & Day), and various aspects of lens fit were evaluated. The steeper base curves of each type were worn in one eye and the flatter base curves in the other eye. Corneal topography data were collected using a Medmont E300 corneal topographer (Camberwell, Australia). Corneal curvature, shape factor (SF), and corneal height were measured over a 10 mm chord and also over the maximum measurable diameter. These were measured in the horizontal, vertical, steepest, and flattest meridians. With each lens type, the steeper base curve provided the best fit on the greatest proportion of eyes and the significant differences in various aspects of fit were noted between base curves. For each lens type, there was no significant difference in mean K-reading between those eyes best fit with the steeper base curve and those eyes best fit with the flatter base curve. Two of the lenses showed a positive correlation between centration and horizontal corneal height (maximum), whereas one lens showed a negative correlation between centration and horizontal SF (SF = e). Several lenses showed a positive correlation between post-blink movement and horizontal or vertical corneal SF. The measurement of corneal topography using current Placido disc instrumentation allows a better prediction of soft lens fit than by keratometry, but it is not reliable enough to enable accurate selection of the best fitting base curve. Some correlations are evident between corneal measurements; however, trial fitting remains the method of choice for selection of soft lens base curve.

  12. Ways to Improve (Visual) Outcome in Corneal Transplantation, Corneal Pathology

    NARCIS (Netherlands)

    M.C. Bartels (Marjolijn)

    2005-01-01

    textabstractThe normally transparent cornea can lose its ability to refract light regularly from various conditions. Among these conditions are corneal opacities and corneal diseases leading to a distortion of the corneal contour. Vision might be restored by a corneal transplantation. Corneal

  13. Regulation of Corneal Stroma Extracellular Matrix Assembly

    Science.gov (United States)

    Chen, Shoujun; Mienaltowski, Michael J.; Birk, David E.

    2014-01-01

    The transparent cornea is the major refractive element of the eye. A finely controlled assembly of the stromal extracellular matrix is critical to corneal function, as well as in establishing the appropriate mechanical stability required to maintain corneal shape and curvature. In the stroma, homogeneous, small diameter collagen fibrils, regularly packed with a highly ordered hierarchical organization, are essential for function. This review focuses on corneal stroma assembly and the regulation of collagen fibrillogenesis. Corneal collagen fibrillogenesis involves multiple molecules interacting in sequential steps, as well as interactions between keratocytes and stroma matrix components. The stroma has the highest collagen V:I ratio in the body. Collagen V regulates the nucleation of protofibril assembly, thus controlling the number of fibrils and assembly of smaller diameter fibrils in the stroma. The corneal stroma is also enriched in small leucine-rich proteoglycans (SLRPs) that cooperate in a temporal and spatial manner to regulate linear and lateral collagen fibril growth. In addition, the fibril-associated collagens (FACITs) such as collagen XII and collagen XIV have roles in the regulation of fibril packing and inter-lamellar interactions. A communicating keratocyte network contributes to the overall and long-range regulation of stromal extracellular matrix assembly, by creating micro-domains where the sequential steps in stromal matrix assembly are controlled. Keratocytes control the synthesis of extracellular matrix components, which interact with the keratocytes dynamically to coordinate the regulatory steps into a cohesive process. Mutations or deficiencies in stromal regulatory molecules result in altered interactions and deficiencies in both transparency and refraction, leading to corneal stroma pathobiology such as stromal dystrophies, cornea plana and keratoconus. PMID:25819456

  14. Vanishing corneal vessels

    Science.gov (United States)

    Nicholson, Luke; Chana, Rupinder

    2013-01-01

    We wish to highlight the importance of acknowledging the accompanying effects of topical phenylephrine drops on the eye other than its intended mydriasis. We reported a case of a 92-year-old woman with a corneal graft who was noted to have superficial corneal vascularisation which was not documented previously. After the instillation of topical tropicamide 1% and phenylephrine 2.5%, for funduscopy, the corneal vascularisation was not visible. When reassessed on another visit, tropicamide had no effect on the vessels and only phenylephrine did. We wish to highlight that when reviewing patients in cornea clinics, instilling phenylephrine prior to being seen may mask important corneal vascularisation. PMID:24121816

  15. Ipsilateral rotational autokeratoplasty for the management of corneal opacities.

    Science.gov (United States)

    Verma, N; Melengas, S; Garap, J A

    1999-02-01

    Penetrating keratoplasty is the logical solution for the management of corneal opacities. In situations such as in Papua New Guinea, where donor corneal tissue is scarce and corneal opacities are plenty, an alternative procedure for the management of corneal opacities in the form of ipsilateral rotational autokeratoplasty was considered. In the present prospective study, ipsilateral rotational autokeratoplasty was performed in 17 eyes over a 2 year period in a general hospital. The patient's cornea was trephined eccentrically and the corneal opacity was dialed out of the visual axis and was replaced by clear peripheral cornea. Most opacities were leucomata (76.4%). The average size of the opacity was 5.1 mm and the corneal button size was 7 mm.A final visual acuity of 6/18 or better was obtained in 64.7% of cases (at 12 months). No significant postoperative complications were encountered. No complex formula was needed to calculate the size of the button and, by simply adding 3 mm to the pupillary diameter in standard illumination, one could make an estimation of the graft diameter. Rotational autokeratoplasty has a definite role in places where donor corneal tissue is scarce, in patients in whom long-term steroids are a risk or in situations where follow up of patients is difficult. Rejection is a theoretical impossibility, but late endothelial failure could occur, requiring regrafting. Rotational autokeratoplasty should be seriously considered as an alternative to conventional penetrating keratoplasty.

  16. Characterization of Corneal Indentation Hysteresis.

    Science.gov (United States)

    Ko, Match W L; Dongming Wei; Leung, Christopher K S

    2015-01-01

    Corneal indentation is adapted for the design and development of a characterization method for corneal hysteresis behavior - Corneal Indentation Hysteresis (CIH). Fourteen porcine eyes were tested using the corneal indentation method. The CIH measured in enucleated porcine eyes showed indentation rate and intraocular pressure (IOP) dependences. The CIH increased with indentation rate at lower IOP ( 25 mmHg). The CIH was linear proportional to the IOP within an individual eye. The CIH was positively correlated with the IOP, corneal in-plane tensile stress and corneal tangent modulus (E). A new method based on corneal indentation for the measurement of Corneal Indentation Hysteresis in vivo is developed. To our knowledge, this is the first study to introduce the corneal indentation hysteresis and correlate the corneal indentation hysteresis and corneal tangent modulus.

  17. corneal pyogenic granuloma

    African Journals Online (AJOL)

    GB

    2012-09-14

    Sep 14, 2012 ... Figure 3: A child with pyogenic cornea granuloma intra operatively. After excision of the mass, central corneal stromal defect developed. The patient was followed up for more than a month with topical antibiotic and cycloplegic. Subsequently, the defect healed and leucoma corneal opacity (figure.

  18. Corneal biomechanics - a review.

    Science.gov (United States)

    Kling, Sabine; Hafezi, Farhad

    2017-05-01

    In recent years, the interest in corneal biomechanics has strongly increased. The material properties of the cornea determine its shape and therefore play an important role in corneal ectasia and related pathologies. This review addresses the molecular origin of biomechanical properties, models for their description, methods for their characterisation, techniques for their modification, and computational simulation approaches. Recent research has focused on developing non-contact techniques to measure the biomechanical properties in vivo, on determining structural and molecular abnormalities in pathological corneas, on developing and optimising techniques to reinforce the corneal tissue and on the computational simulation of surgical interventions. A better understanding of corneal biomechanics will help to improve current refractive surgeries, allow an earlier diagnosis of ectatic disorders and a better quantification of treatments aiming at reinforcing the corneal tissue. © 2017 The Authors Ophthalmic & Physiological Optics © 2017 The College of Optometrists.

  19. CORNEAL BLINDNESS AND XENOTRANSPLANTATION

    Science.gov (United States)

    Lamm, Vladimir; Hara, Hidetaka; Mammen, Alex; Dhaliwal, Deepinder; Cooper, David K.C.

    2014-01-01

    Approximately 39 million people are blind worldwide, with an estimated 285 million visually impaired. The developing world shoulders 90% of the world’s blindness, with 80% of causative diseases being preventable or treatable. Blindness has a major detrimental impact on the patient, community, and healthcare spending. Corneal diseases are significant causes of blindness, affecting at least 4 million people worldwide. The prevalence of corneal disease varies among parts of the world. Trachoma, for instance, is the second leading cause of blindness in Africa, after cataracts, but is rarely found today in developed nations. When preventive strategies have failed, corneal transplantation is the most effective treatment for advanced corneal disease. The major surgical techniques for corneal transplantation include penetrating keratoplasty (PK), anterior lamellar keratoplasty (ALK), and endothelial keratoplasty (EK). Indications for corneal transplantation vary among countries, with Fuchs’ dystrophy being the leading indication in the U.S. and keratoconus in Australia. With the exception of the US, where EK will soon overtake PK as the most common surgical procedure, PK is the overwhelming procedure of choice. Success using corneal grafts in developing nations, such as Nepal, demonstrates the feasibility of corneal transplantation on a global scale. The number of suitable corneas from deceased human donors that becomes available will never be sufficient, and so research into various alternatives, e.g., stem cells, amniotic membrane transplantation, synthetic and biosynthetic corneas, and xenotransplantation, is progressing. While each of these has potential, we suggest that xenotransplantation holds the greatest potential for a corneal replacement. With the increasing availability of genetically-engineered pigs, pig corneas may alleviate the global shortage of corneas in the near future. PMID:25268248

  20. Riboflavin concentration in corneal stroma after intracameral injection

    Directory of Open Access Journals (Sweden)

    Na Li

    2015-06-01

    Full Text Available AIM:To evaluate the enrichment of riboflavin in the corneal stroma after intracameral injection to research the barrier ability of the corneal endothelium to riboflavin in vivo.METHODS:The right eyes of 30 New Zealand white rabbits were divided into three groups. Different concentrations riboflavin-balanced salt solutions (BSS were injected into the anterior chamber (10 with 0.5%, 10 with 1%, and 10 with 2%. Eight corneal buttons of 8.5 mm in diameter from each group were dissected at 30min after injection and the riboflavin concentrations in the corneal stroma were determined using high-performance liquid chromatography (HPLC after removing the epithelium and endothelium. The other two rabbits in every group were observed for 24h and sacrificed. As a comparison, the riboflavin concentrations from 16 corneal stromal samples were determined using HPLC after instillation of 0.1% riboflavin-BSS solution for 30min on the corneal surface (8 without epithelium and 8 with intact epithelium.RESULTS: The mean riboflavin concentrations were 11.19, 18.97, 25.08, 20.18, and 1.13 µg/g for 0.5%, 1%, 2%, de-epithelialzed samples, and the transepithelial groups, respectively. The color change of the corneal stroma and the HPLC results showed that enrichment with riboflavin similar to classical de-epithelialized corneal collagen crosslinking (CXL could be achieved by intracameral1% riboflavin-BSS solution after 30min; the effect appeared to be continuous for at least 30min.CONCLUSION:Riboflavin can effectively penetrate the corneal stroma through the endothelium after an intracameral injection in vivo, so it could be an enhancing method that could improve the corneal riboflavin concentration in transepithelial CXL.

  1. Corneal transplant - slideshow

    Science.gov (United States)

    ... ency/presentations/100082.htm Corneal transplant - series—Normal anatomy To use the sharing features on this page, ... Bethesda, MD 20894 U.S. Department of Health and Human Services National Institutes of Health Page last updated: ...

  2. Corneal Higher-Order Aberrations in Infectious Keratitis.

    Science.gov (United States)

    Shimizu, Eisuke; Yamaguchi, Takefumi; Yagi-Yaguchi, Yukari; Dogru, Murat; Satake, Yoshiyuki; Tsubota, Kazuo; Shimazaki, Jun

    2017-03-01

    To characterize the corneal higher-order aberrations (HOAs) in eyes with Acanthamoeba keratitis (AK), bacterial keratitis (BK), and fungal keratitis (FK). Retrospective consecutive case series. This retrospective study includes 18 normal subjects and 63 eyes of 62 consecutive patients with corneal scarring due to AK (20 eyes), BK (35 eyes), and FK (8 eyes) from 2010 to 2016. HOAs of the anterior and posterior surfaces and the total cornea were analyzed by anterior segment optical coherence tomography. Corneal HOA patterns were assigned on the basis of corneal topography maps. Corneal opacity grading was assigned on the basis of slit-lamp examinations. We evaluated corneal HOAs, corneal opacity grading, and their correlation with visual acuity. HOAs of the total cornea within a 4-mm diameter were significantly larger in eyes with infectious keratitis (AK, 1.15 ± 2.06 μm; BK, 0.91 ± 0.88 μm; FK, 1.39 ± 1.46 μm) compared with normal controls (0.09 ± 0.01 μm, all, P keratitis were associated with poorer visual acuity values. Asymmetric pattern was the most common topographic pattern in infectious keratitis. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. [Corneal trophism and sensitivity changes after penetrating keratoplasty].

    Science.gov (United States)

    Javaloy Estañ J; Aracil Marco A; Belmonte Martínez J; Gallar, J

    2000-09-01

    To evaluate in the rabbit eye the changes in mechanical sensitivity and trophic function of the corneal epithelium after the denervation consecutive to circular trephinations of the peripheral cornea, similar to those produced by penetrating keratoplasty. Complete trephination (8 mm diameter) with rotation of corneal button (PK) was performed in 12 eyes. Non-penetrating trephination, affecting 2/3 of the corneal depth, was made in a group of 12 eyes (NPK). A separate group of 16 nonoperated eyes served as control. Mechanical corneal sensitivity was measured with the Cochet-Bonnet esthesiometer (No. 12 filament). Trophic function of the corneal epithelium was assessed by determining the healing rate of epithelial wounds performed with n-heptanol. Three months after surgery, sensitivity in the center of the cornea was significantly reduced in both PK and NPK eyes (240+/-0 mg/S and 179+/-20 mg/S, respectively) when compared with control (88+/-10 mg/S, pPK and NPK eyes. Results suggest that three months after corneal graft, throphic maintenance of the epithelium remains unaffected in spite of the significant hypoesthesia recorded at this time. Further experiments are needed to analyze the interaction between corneal epithelial cells and the trigeminal neurons innervating the cornea

  4. Corneal collagen crosslinking for keratoconus. A review

    Directory of Open Access Journals (Sweden)

    M. M. Bikbov

    2014-01-01

    C, and collagen fiber diameter increase by 12.2 % (anterior stroma and 4.6 % (posterior stroma. In mild bullous keratopathy, corneal crosslinking provides antimicrobial effect. In moderate and severe keratopathy, crosslinking reduces pain and corneal edema and improves visual acuity immediately after the procedure. A case of HSV keratitis exacerbation was described. Amongst the complications, infection, halos, and posterior segment damage should be mentioned. Poor refractive results can be improved by the implantation of intrastromal corneal ring segments.

  5. Corneal collagen crosslinking for keratoconus. A review

    Directory of Open Access Journals (Sweden)

    M. M. Bikbov

    2014-10-01

    C, and collagen fiber diameter increase by 12.2 % (anterior stroma and 4.6 % (posterior stroma. In mild bullous keratopathy, corneal crosslinking provides antimicrobial effect. In moderate and severe keratopathy, crosslinking reduces pain and corneal edema and improves visual acuity immediately after the procedure. A case of HSV keratitis exacerbation was described. Amongst the complications, infection, halos, and posterior segment damage should be mentioned. Poor refractive results can be improved by the implantation of intrastromal corneal ring segments.

  6. The molecular basis of corneal transparency.

    Science.gov (United States)

    Hassell, John R; Birk, David E

    2010-09-01

    The cornea consists primarily of three layers: an outer layer containing an epithelium, a middle stromal layer consisting of a collagen-rich extracellular matrix (ECM) interspersed with keratocytes and an inner layer of endothelial cells. The stroma consists of dense, regularly packed collagen fibrils arranged as orthogonal layers or lamellae. The corneal stroma is unique in having a homogeneous distribution of small diameter 25-30 nm fibrils that are regularly packed within lamellae and this arrangement minimizes light scattering permitting transparency. The ECM of the corneal stroma consists primarily of collagen type I with lesser amounts of collagen type V and four proteoglycans: three with keratan sulfate chains; lumican, keratocan, osteoglycin and one with a chondroitin sulfate chain; decorin. It is the core proteins of these proteoglycans and collagen type V that regulate the growth of collagen fibrils. The overall size of the proteoglycans are small enough to fit in the spaces between the collagen fibrils and regulate their spacing. The stroma is formed during development by neural crest cells that migrate into the space between the corneal epithelium and corneal endothelium and become keratoblasts. The keratoblasts proliferate and synthesize high levels of hyaluronan to form an embryonic corneal stroma ECM. The keratoblasts differentiate into keratocytes which synthesize high levels of collagens and keratan sulfate proteoglycans that replace the hyaluronan/water-rich ECM with the densely packed collagen fibril-type ECM seen in transparent adult corneas. When an incisional wound through the epithelium into stroma occurs the keratocytes become hypercellular myofibroblasts. These can later become wound fibroblasts, which provides continued transparency or become myofibroblasts that produce a disorganized ECM resulting in corneal opacity. The growth factors IGF-I/II are likely responsible for the formation of the well organized ECM associated with transparency

  7. Failure Diameter Resolution Study

    Energy Technology Data Exchange (ETDEWEB)

    Menikoff, Ralph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-12-19

    Previously the SURFplus reactive burn model was calibrated for the TATB based explosive PBX 9502. The calibration was based on fitting Pop plot data, the failure diameter and the limiting detonation speed, and curvature effect data for small curvature. The model failure diameter is determined utilizing 2-D simulations of an unconfined rate stick to find the minimum diameter for which a detonation wave propagates. Here we examine the effect of mesh resolution on an unconfined rate stick with a diameter (10mm) slightly greater than the measured failure diameter (8 to 9 mm).

  8. Corneal collagen cross-linking and liposomal amphotericin B combination therapy for fungal keratitis in rabbits

    Directory of Open Access Journals (Sweden)

    Zhao-Qin Hao

    2016-11-01

    Full Text Available AIM: To observe the therapeutic effect of corneal collagen cross-linking (CXL in combination with liposomal amphotericin B in fungal corneal ulcers. METHODS: New Zealand rabbits were induced fungal corneal ulcers by scratching and randomly divided into 3 groups, i.e. control, treated with CXL, and combined therapy of CXL with 0.25% liposomal amphotericin B (n=5 each. The corneal lesions were documented with slit-lamp and confocal microscopy on 3, 7, 14, 21 and 28d after treatment. The corneas were examined with transmission electron microscopy (TEM at 4wk. RESULTS: A rabbit corneal ulcer model of Fusarium was successfully established. The corneal epithelium defect areas in the two treatment groups were smaller than that in the control group on 3, 7, 14 and 21d (P<0.05. The corneal epithelium defect areas of the combined group was smaller than that of the CXL group (P<0.05 on 7 and 14d, but there were no statistical differences on 3, 21 and 28d. The corneal epithelium defects of the two treatment groups have been healed by day 21. The corneal epithelium defects of the control group were healed on 28d. The diameters of the corneal collagen fiber bundles (42.960±7.383 nm in the CXL group and 37.040±4.160 nm in the combined group were thicker than that of the control group (24.900±1.868 nm, but there was no difference between the two treatment groups. Some corneal collagen fiber bundles were distorted and with irregular arrangement, a large number of fibroblasts could be seen among them but no inflammatory cells in both treatment groups. CONCLUSION: CXL combined with liposomal amphotericin B have beneficial effects on fungal corneal ulcers. The combined therapy could alleviate corneal inflammattions, accelerate corneal repair, and shorten the course of disease.

  9. Corneal stroma microfibrils

    KAUST Repository

    Hanlon, Samuel D.

    2015-03-01

    Elastic tissue was first described well over a hundred years ago and has since been identified in nearly every part of the body. In this review, we examine elastic tissue in the corneal stroma with some mention of other ocular structures which have been more thoroughly described in the past. True elastic fibers consist of an elastin core surrounded by fibrillin microfibrils. However, the presence of elastin fibers is not a requirement and some elastic tissue is comprised of non-elastin-containing bundles of microfibrils. Fibers containing a higher relative amount of elastin are associated with greater elasticity and those without elastin, with structural support. Recently it has been shown that the microfibrils, not only serve mechanical roles, but are also involved in cell signaling through force transduction and the release of TGF-β. A well characterized example of elastin-free microfibril bundles (EFMBs) is found in the ciliary zonules which suspend the crystalline lens in the eye. Through contraction of the ciliary muscle they exert enough force to reshape the lens and thereby change its focal point. It is believed that the molecules comprising these fibers do not turn-over and yet retain their tensile strength for the life of the animal. The mechanical properties of the cornea (strength, elasticity, resiliency) would suggest that EFMBs are present there as well. However, many authors have reported that, although present during embryonic and early postnatal development, EFMBs are generally not present in adults. Serial-block-face imaging with a scanning electron microscope enabled 3D reconstruction of elements in murine corneas. Among these elements were found fibers that formed an extensive network throughout the cornea. In single sections these fibers appeared as electron dense patches. Transmission electron microscopy provided additional detail of these patches and showed them to be composed of fibrils (~10nm diameter). Immunogold evidence clearly

  10. Distrofia corneal de Schnyder

    Directory of Open Access Journals (Sweden)

    Michel Guerra Almaguer

    Full Text Available La principal entidad hereditaria con depósitos de lípidos en el estroma corneal es la distrofia cristalina central, conocida como distrofia de Schnyder, quien la describió en Suiza en 1927. Se caracteriza por depósitos blanco-amarillentos en el estroma corneal central y superficial. Se presenta un paciente de 28 años, del sexo masculino y piel negra, con antecedente de salud anterior. Acudió a consulta y refirió una disminución de la visión y cambio de coloración progresiva de ambos ojos, de años de evolución. En la exploración oftalmológica de ambos ojos se apreciaron lesiones blanquecinas anulares a nivel del estroma corneal, con ligera turbidez corneal central. Los estudios refractivos realizados constataron un astigmatismo hipermetrópico simple. El resto del examen oftalmológico fue negativo. Para el diagnóstico de certeza se empleó el microscopio confocal. Se concluye que el caso presenta una distrofia corneal estromal de tipo cristalina, de Schnyder.

  11. Research progress of corneal transplantation

    OpenAIRE

    Bing-Jie Zhang; Heng Sun; Yuan-Ping Zhang; Lin-Kun Ma

    2015-01-01

    Corneal transplantation is an ophthalmology treatment technique for corneal disease to help restore vision or control the development of corneal diseases by removing a scarred or damaged host cornea and replacing it with a clear and healthy donor cornea. Traditional corneal transplantation includes penetrating keratoplasty and lamellar keratoplasty. In recent ten years, deep lamellar keratoplasty and endothelial keratoplasty have gradually developed. At present, the development of keratoprost...

  12. Experimental circular keratotomy for correction of corneal astigmatism

    NARCIS (Netherlands)

    Wijdh, RH; van Rij, G

    1998-01-01

    PURPOSE: To investigate the effect of circular keratotomy depth and diameter on corneal astigmatism. METHODS: High astigmatism was induced in 25 human donor eyes by an anterior radial 7-0 silk suture across the corneoscleral limbus. With a 6.0, 6.5, 7.0, or 7.5 mm trephine, a 0.3 mm deep circular

  13. Airbag induced corneal ectasia.

    Science.gov (United States)

    Mearza, Ali A; Koufaki, Fedra N; Aslanides, Ioannis M

    2008-02-01

    To report a case of airbag induced corneal ectasia. Case report. A patient 3 years post-LASIK developed bilateral corneal ectasia worse in the right eye following airbag deployment in a road traffic accident. At last follow up, best corrected vision was 20/40 with -4.00/-4.00 x 25 in the right eye and 20/25 with -1.25/-0.50 x 135 in the left eye. This is a rare presentation of trauma induced ectasia in a patient post-LASIK. It is possible that reduction in biomechanical integrity of the cornea from prior refractive surgery contributed to this presentation.

  14. Oxidized alginate hydrogels as niche environments for corneal epithelial cells

    Science.gov (United States)

    Wright, Bernice; De Bank, Paul A; Luetchford, Kim A; Acosta, Fernando R; Connon, Che J

    2014-01-01

    Chemical and biochemical modification of hydrogels is one strategy to create physiological constructs that maintain cell function. The aim of this study was to apply oxidised alginate hydrogels as a basis for development of a biomimetic niche for limbal epithelial stem cells that may be applied to treating corneal dysfunction. The stem phenotype of bovine limbal epithelial cells (LEC) and the viability of corneal epithelial cells (CEC) were examined in oxidised alginate gels containing collagen IV over a 3-day culture period. Oxidation increased cell viability (P ≤ 0.05) and this improved further with addition of collagen IV (P ≤ 0.01). Oxidised gels presented larger internal pores (diameter: 0.2–0.8 µm) than unmodified gels (pore diameter: 0.05–0.1 µm) and were significantly less stiff (P ≤ 0.001), indicating that an increase in pore size and a decrease in stiffness contributed to improved cell viability. The diffusion of collagen IV from oxidised alginate gels was similar to that of unmodified gels suggesting that oxidation may not affect the retention of extracellular matrix proteins in alginate gels. These data demonstrate that oxidised alginate gels containing corneal extracellular matrix proteins can influence corneal epithelial cell function in a manner that may impact beneficially on corneal wound healing therapy. © 2013 The Authors. Journal of Biomedical Materials Research Part A Published byWiley Periodicals, Inc. Part A: 102A: 3393–3400, 2014. PMID:24142706

  15. Research progress of corneal transplantation

    Directory of Open Access Journals (Sweden)

    Bing-Jie Zhang

    2015-06-01

    Full Text Available Corneal transplantation is an ophthalmology treatment technique for corneal disease to help restore vision or control the development of corneal diseases by removing a scarred or damaged host cornea and replacing it with a clear and healthy donor cornea. Traditional corneal transplantation includes penetrating keratoplasty and lamellar keratoplasty. In recent ten years, deep lamellar keratoplasty and endothelial keratoplasty have gradually developed. At present, the development of keratoprosthesis provides a new choice for the patients no suitable for traditional. The review describes current surgical techniques in the field of corneal transplantation about indications, postoperative complications, and so on.

  16. Alternatives to allograft corneal transplantation.

    Science.gov (United States)

    Jhanji, Vishal; Sharma, Namrata; Agarwal, Tushar; Vajpayee, Rasik B

    2010-07-01

    Corneal transplantation is the most commonly performed solid organ transplantation in the world. Despite a glorious history of more than a 100 years, the success of conventional corneal transplantation surgery is marred by problems like graft rejection,graft infection and associated glaucoma due to long-term use of topical corticosteroids.In addition there is a dearth of donor corneal tissue in some parts of the world which subsequently adds on to the existing burden on the eye banks every year. We propose alternatives to the conventional corneal transplantation surgery for the management of corneal scarring. The potential use of alternatives to allograft corneal transplantation surgery has been described by corneal surgeons around the world. These techniques consist of nonsurgical interventions like contact lens fitting. Surgical alternatives include excimer laser phototherapeutic keratectomy, optical iridectomy, rotational autokeratoplasty and contralateral autokeratoplasty. Although these techniques are not practiced routinely, however, their appropriate utilization would clearly help the corneal surgeons to get rid of certain problems associated with allograft corneal transplantation. Careful selection of patients can yield encouraging results with the use of these alternative techniques. Visual outcomes may not be as good as after a routine keratoplasty; nevertheless, this setback is outweighed by advantages such as absence of corneal graft rejection. We also believe that the use of these techniques would at least partially resolve the issue of scarcity of donor corneal tissue in the developing world.

  17. Spontaneous Corneal Hydrops in a Patient with a Corneal Ulcer

    Directory of Open Access Journals (Sweden)

    Hatim Batawi

    2016-01-01

    Full Text Available Purpose: We report the case of a 77-year-old man with no history of keratoconus or other ectatic disorders who presented with corneal hydrops in the setting of a corneal ulcer. The risk factors, pathogenesis and treatment options of corneal hydrops are discussed. Method: This is an observational case report study. Results: A 77-year-old man presented with a 1-day history of severe pain, redness, mucous discharge and photophobia in the right eye. A slit-lamp examination of the right eye showed an area of focal corneal edema and protrusion. Within the area of edema and protrusion, there was an infiltrate with an overlying epithelial defect consistent with an infectious corneal ulcer. The Seidel test showed no leakage, so a clinical diagnosis of corneal hydrops associated with nonperforated corneal ulcer was made. With appropriate antibiotic treatment, the corneal ulcer and hydrops both resolved over a 1-month period. Conclusion: Corneal hydrops can occur in the setting of corneal infections.

  18. Massive corneal edema treated with corneal cross-linking.

    Science.gov (United States)

    Laborante, A; Buzzonetti, L; Longo, C

    2012-01-01

    Massive corneal edema disrupts the fine architecture of corneal stroma that guarantees its transparency, causing opacities that seriously impair clear vision and are usually solved by corneal transplant. Corneal cross-linking, a treatment developed to halt keratoconus progression, results in a loss of water and a compaction of corneal stroma. It might therefore be useful to improve the pathologic edematous condition of some corneas, ameliorating visual acuity and allowing more time for a surgical procedure of keratoplasty. Six patients with visual impairing corneal edemas further to lens phacoemulsification, penetrating keratoplasty, or post-infective neovascularization were treated with corneal cross-linking alone, or in combination with amniotic membrane apposition with or without anti-angiogenic therapy. All patients partly resolved the edematous condition, improving both corneal transparency and visual acuity. Corneal cross-linking appears to be a useful method to treat massive corneal edemas, so that keratoplasty can be at least delayed, and need not to be an emergency treatment in these cases.

  19. Corneal biomechanical properties from air-puff corneal deformation imaging

    Science.gov (United States)

    Marcos, Susana; Kling, Sabine; Bekesi, Nandor; Dorronsoro, Carlos

    2014-02-01

    The combination of air-puff systems with real-time corneal imaging (i.e. Optical Coherence Tomography (OCT), or Scheimpflug) is a promising approach to assess the dynamic biomechanical properties of the corneal tissue in vivo. In this study we present an experimental system which, together with finite element modeling, allows measurements of corneal biomechanical properties from corneal deformation imaging, both ex vivo and in vivo. A spectral OCT instrument combined with an air puff from a non-contact tonometer in a non-collinear configuration was used to image the corneal deformation over full corneal cross-sections, as well as to obtain high speed measurements of the temporal deformation of the corneal apex. Quantitative analysis allows direct extraction of several deformation parameters, such as apex indentation across time, maximal indentation depth, temporal symmetry and peak distance at maximal deformation. The potential of the technique is demonstrated and compared to air-puff imaging with Scheimpflug. Measurements ex vivo were performed on 14 freshly enucleated porcine eyes and five human donor eyes. Measurements in vivo were performed on nine human eyes. Corneal deformation was studied as a function of Intraocular Pressure (IOP, 15-45 mmHg), dehydration, changes in corneal rigidity (produced by UV corneal cross-linking, CXL), and different boundary conditions (sclera, ocular muscles). Geometrical deformation parameters were used as input for inverse finite element simulation to retrieve the corneal dynamic elastic and viscoelastic parameters. Temporal and spatial deformation profiles were very sensitive to the IOP. CXL produced a significant reduction of the cornea indentation (1.41x), and a change in the temporal symmetry of the corneal deformation profile (1.65x), indicating a change in the viscoelastic properties with treatment. Combining air-puff with dynamic imaging and finite element modeling allows characterizing the corneal biomechanics in-vivo.

  20. Pilot Study for OCT Guided Design and Fit of a Prosthetic Device for Treatment of Corneal Disease.

    Science.gov (United States)

    Le, Hong-Gam T; Tang, Maolong; Ridges, Ryan; Huang, David; Jacobs, Deborah S

    2012-01-01

    Purpose. To assess optical coherence tomography (OCT) for guiding design and fit of a prosthetic device for corneal disease. Methods. A prototype time domain OCT scanner was used to image the anterior segment of patients fitted with large diameter (18.5-20 mm) prosthetic devices for corneal disease. OCT images were processed and analyzed to characterize corneal diameter, corneal sagittal height, scleral sagittal height, scleral toricity, and alignment of device. Within-subject variance of OCT-measured parameters was evaluated. OCT-measured parameters were compared with device parameters for each eye fitted. OCT image correspondence with ocular alignment and clinical fit was assessed. Results. Six eyes in 5 patients were studied. OCT measurement of corneal diameter (coefficient of variation, CV = 0.76%), cornea sagittal height (CV = 2.06%), and scleral sagittal height (CV = 3.39%) is highly repeatable within each subject. OCT image-derived measurements reveal strong correlation between corneal sagittal height and device corneal height (r = 0.975) and modest correlation between scleral and on-eye device toricity (r = 0.581). Qualitative assessment of a fitted device on OCT montages reveals correspondence with slit lamp images and clinical assessment of fit. Conclusions. OCT imaging of the anterior segment is suitable for custom design and fit of large diameter (18.5-20 mm) prosthetic devices used in the treatment of corneal disease.

  1. Pilot Study for OCT Guided Design and Fit of a Prosthetic Device for Treatment of Corneal Disease

    Directory of Open Access Journals (Sweden)

    Hong-Gam T. Le

    2012-01-01

    Full Text Available Purpose. To assess optical coherence tomography (OCT for guiding design and fit of a prosthetic device for corneal disease. Methods. A prototype time domain OCT scanner was used to image the anterior segment of patients fitted with large diameter (18.5–20 mm prosthetic devices for corneal disease. OCT images were processed and analyzed to characterize corneal diameter, corneal sagittal height, scleral sagittal height, scleral toricity, and alignment of device. Within-subject variance of OCT-measured parameters was evaluated. OCT-measured parameters were compared with device parameters for each eye fitted. OCT image correspondence with ocular alignment and clinical fit was assessed. Results. Six eyes in 5 patients were studied. OCT measurement of corneal diameter (coefficient of variation, %, cornea sagittal height (%, and scleral sagittal height (% is highly repeatable within each subject. OCT image-derived measurements reveal strong correlation between corneal sagittal height and device corneal height ( and modest correlation between scleral and on-eye device toricity (. Qualitative assessment of a fitted device on OCT montages reveals correspondence with slit lamp images and clinical assessment of fit. Conclusions. OCT imaging of the anterior segment is suitable for custom design and fit of large diameter (18.5–20 mm prosthetic devices used in the treatment of corneal disease.

  2. Corneal lathing using the excimer laser and a computer-controlled positioning system: Part II--Variable trephination of corneal buttons.

    Science.gov (United States)

    Husinsky, W; Mitterer, S; Altmann, J; Grabner, G; Baumgartner, I; Skorpik, F; Asenbauer, T

    1991-01-01

    A new system is presented that allows a variable trephination of donor corneas for the preparation of corneal buttons used in penetrating keratoplasty. With the help of a computer-controlled positioning system that uses high-precision micropositioning elements (both translation and rotational stages) the donor cornea is removed, epithelial side up, in a fixation device in front of a focused excimer laser beam (ArF, lambda = 193 nm). User friendly computer software allows the surgeon to select a variety of parameters (diameter, shape, angle of trephination) of the corneal graft. Histological and electron microscopical data of human corneas trephined with this "Excimer Laser Corneal Shaping System" are presented.

  3. Pupil response to tropicamide following corneal crosslinking.

    Science.gov (United States)

    Kymionis, George D; Paraskevopoulos, Theodore A; Liakopoulos, Dimitrios A; Grentzelos, Michael A; Kouroupaki, Anna I; Tsoulnaras, Konstantinos I; Panagopoulou, Sophia I; Mazzotta, Cosimo; Detorakis, Efstathios T

    2016-08-04

    To evaluate the effect of corneal crosslinking (CXL) with ultraviolet A (UVA) irradiation on pupil response to tropicamide 0.5% instillation. This prospective interventional study enrolled 17 patients (19 eyes) with progressive keratoconus who underwent CXL with UVA irradiation. Central corneal thickness (CCT) was evaluated with the use of anterior segment optical coherence tomography (Visante OCT 3.0). Pupil diameter was measured with the use of Colvard infrared pupillometer before the instillation of tropicamide 0.5% and after the instillation of tropicamide every 5 minutes for total duration of 30 minutes. Corneal epithelial integrity was examined with the use of fluorescein dye staining. Measurements were performed 1 day preoperatively and 1 month postoperatively, with emphasis on simulating the same light conditions regarding the pupil measurements. No intraoperative or postoperative complications were observed in any of the patients. Mean CCT decreased significantly (p<0.001) 1 month postoperatively. Mean postoperative pupil size did not change significantly at any time point compared to the mean preoperative measurements. The CXL procedure seems not to impair effectiveness of topical drugs, using pupil size measurements after tropicamide 0.5% instillation.

  4. Computational Model for Corneal Transplantation

    Science.gov (United States)

    Cabrera, Delia

    2003-10-01

    We evaluated the refractive consequences of corneal transplants using a biomechanical model with homogeneous and inhomogeneous Young's modulus distributions within the cornea, taking into account ablation of some stromal tissue. A FEM model was used to simulate corneal transplants in diseased cornea. The diseased cornea was modeled as an axisymmetric structure taking into account a nonlinearly elastic, isotropic formulation. The model simulating the penetrating keratoplasty procedure gives more change in the postoperative corneal curvature when compared to the models simulating the anterior and posterior lamellar graft procedures. When a lenticle shaped tissue was ablated in the graft during the anterior and posterior keratoplasty, the models provided an additional correction of about -3.85 and -4.45 diopters, respectively. Despite the controversy around the corneal thinning disorders treatment with volume removal procedures, results indicate that significant changes in corneal refractive power could be introduced by a corneal transplantation combined with myopic laser ablation.

  5. Human corneal epithelial subpopulations

    DEFF Research Database (Denmark)

    Søndergaard, Chris Bath

    2013-01-01

    subpopulations in human corneal epithelium using a combination of laser capture microdissection and RNA sequencing for global transcriptomic profiling. We compared dissociation cultures, using either expansion on γ-irradiated NIH/3T3 feeder cells in serum-rich medium or expansion directly on plastic in serum......-free EpiLife medium, using a range of physiologically relevant oxygen concentrations (2%, 5%, 10%, 15% and 20%). Using immunocytochemistry and advanced fluorescence microscopy, cells were characterized regarding growth, cell cycle distribution, colony-forming efficiency (CFE), phenotypes...... was not dependent on the system used for propagation (Bath et al. 2013a). Laser capture microdissection was used to isolate cellular subpopulations in situ from the spatially defined differentiation pathway in human corneal epithelium according to an optimized protocol for maintenance of expression profiles...

  6. Biomechanics of Corneal Ring Implants

    OpenAIRE

    Daxer, Albert

    2015-01-01

    Purpose: To evaluate the biomechanics of corneal ring implants by providing a related mathematical theory and biomechanical model for the treatment of myopia and keratoconus. Methods: The spherical dome model considers the inhomogeneity of the tunica of the eye, dimensions of the cornea, lamellar structure of the corneal stroma, and asphericity of the cornea. It is used in this study for calculating a strengthening factor sf for the characterization of different ring-shaped corneal implant de...

  7. Corneal biomechanics: a review

    OpenAIRE

    Piñero Llorens, David Pablo; Alcón, Natividad

    2014-01-01

    Biomechanics is often defined as ‘mechanics applied to biology’. Due to the variety and complexity of the behaviour of biological structures and materials, biomechanics is better defined as the development, extension and application of mechanics for a better understanding of physiology and physiopathology and consequently for a better diagnosis and treatment of disease and injury. Different methods for the characterisation of corneal biomechanics are reviewed in detail, including those that a...

  8. Diameter Perfect Lee Codes

    CERN Document Server

    Horak, Peter

    2011-01-01

    Lee codes have been intensively studied for more than 40 years. Interest in these codes has been triggered by the Golomb-Welch conjecture on the existence of perfect error-correcting Lee codes. In this paper we deal with the existence and enumeration of diameter perfect Lee codes. As main results we determine all q for which there exists a linear diameter-4 perfect Lee code of word length n over Z_{q}, and prove that for each n\\geq3 there are unaccountably many diameter-4 perfect Lee codes of word length n over Z. This is in a strict contrast with perfect error-correcting Lee codes of word length n over Z as there is a unique such code for n=3, and its is conjectured that this is always the case when 2n+1 is a prime. Diameter perfect Lee codes will be constructed by an algebraic construction that is based on a group homomorphism. This will allow us to design an efficient algorithm for their decoding.

  9. Corneal changes following near work in myopic anisometropia.

    Science.gov (United States)

    Vincent, Stephen J; Collins, Michael J; Read, Scott A; Carney, Leo G; Yap, Maurice K H

    2013-01-01

    To examine the symmetry of corneal changes following near work in the fellow eyes of non-amblyopic myopic anisometropes. Thirty-four non-amblyopic, myopic anisometropes (minimum 1 D spherical equivalent anisometropia) had corneal topography measured before and after a controlled near work task. Subjects were positioned in a headrest to minimise head movements and read continuous text on a computer monitor for 10 min at an angle of 25 degrees downward gaze and an accommodation demand of 2.5 D. Measures of the morphology of the palpebral aperture during primary and downward gaze were also obtained. The more and less myopic eyes exhibited a high degree of interocular symmetry for measures of palpebral aperture morphology during both primary and downward gaze. Following the near work task, fellow eyes also displayed a symmetrical change in superior corneal topography (hyperopic defocus) which correlated with the position of the upper eyelid during downward gaze. Greater changes in the spherical corneal power vector (M) following reading were associated with a narrower palpebral aperture during downward gaze (p = 0.07 for more myopic and p = 0.03 for less myopic eyes). A significantly greater change in J0 (an increase in against the rule astigmatism) was observed in the more myopic eyes (-0.04 ± 0.04 D) compared to the less myopic eyes (-0.02 ± 0.06 D) over a 6 mm corneal diameter (p = 0.01). Changes in corneal topography following near work are highly symmetrical between the fellow eyes of myopic anisometropes due to the interocular symmetry of the palpebral aperture. However, the more myopic eye exhibits changes in corneal astigmatism of greater magnitude compared to the less myopic eye. Ophthalmic & Physiological Optics © 2012 The College of Optometrists.

  10. Corneal and scleral collagens--a microscopist's perspective.

    Science.gov (United States)

    Meek, K M; Fullwood, N J

    2001-04-01

    This paper reviews our existing understanding of the distribution and organisation of collagen types within the corneal and scleral stroma from a microscopical perspective. The contribution of various types of light microscopy, electron microscopy and atomic force microscopy to this field are separately discussed. Light microscopy was used in the earliest studies of the cornea and lead to the first description of the lamellar structure of the stroma. More recently polarised light microscopy has been used to obtain specific information on fibril orientation within individual lamellae. Light microscope immunolabelling techniques have been utilised to determine the distribution of several collagen types within the cornea and sclera, while recent developments in confocal microscopy have allowed detailed observations to be made on live cornea. Scanning electron microscopy has proved useful in determining the 3D organisation of lamellae within both corneal and scleral stroma. The transmission electron microscope was responsible for first revealing the regular diameter and high degree of order of the collagen fibrils present in the corneal stroma and contrasting this with the irregular diameter of fibrils present in sclera. This finding lead directly to the formulation of a theory of corneal transparency based on the uniformity of fibril diameter and packing. The use of specialised stains such as cuprolinic blue allowed direct observation of the glycosaminoglycan chains on proteoglycan molecules in cornea and sclera. These images allowed the binding sites of the proteoglycans along the collagen fibrils to be identified and provided convincing evidence for the importance of the proteoglycan molecules in collagen fibril organisation. Immunogold labelling has been used to map the distribution of several collagen types within the corneal and scleral stroma at the ultrastructural level and provided critical evidence for the role of type V collagen in the regulation of fibril

  11. Corneal Densitometry as a Novel Technique for Monitoring Amiodarone Therapy.

    Science.gov (United States)

    Alnawaiseh, Maged; Zumhagen, Lars; Zumhagen, Sven; Schulte, Lea; Rosentreter, André; Schubert, Friederike; Eter, Nicole; Mönnig, Gerold

    2016-11-01

    The clinical efficacy and toxicity of amiodarone may be determined more effectively by tissue deposition than by levels of the agent in serum. Therefore, corneal densitometry might be useful for therapeutic monitoring. The aim of the study is to evaluate Scheimpflug corneal densitometry in patients with amiodarone keratopathy (AK). Comparative case series. Sixty-six patients receiving amiodarone therapy and 66 healthy controls were consecutively enrolled in this study. Patients were examined using the Oculus Pentacam (Wetzlar, Germany). Densitometry data from different corneal layers and different annuli were extracted, analyzed, and compared with densitometry values of healthy controls. Duration of treatment, cumulative dose, Orlando stage (slit-lamp biomicroscopy), and serum concentrations of amiodarone and N-desethylamiodarone also were determined, and the correlation to different densitometry data was evaluated. The total corneal light backscatter at total corneal thickness and at total diameter was significantly higher in the amiodarone group compared with the control group (AK group: 28.3±5.2; control group: 24.4±4.2; P amiodarone therapy. The serum concentration of the active metabolite N-desethylamiodarone correlates with the extent of keratopathy in the anterior layer, whereas chronic changes in the stroma correlate with the cumulative dose and duration of treatment. Copyright © 2016 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

  12. Correlations between corneal hysteresis, intraocular pressure, and corneal central pachymetry.

    Science.gov (United States)

    Touboul, David; Roberts, Cynthia; Kérautret, Julien; Garra, Caroline; Maurice-Tison, Sylvie; Saubusse, Elodie; Colin, Joseph

    2008-04-01

    To analyze the correlation between corneal hysteresis (CH) measured with the Ocular Response Analyzer (ORA, Reichert) and ultrasonic corneal central thickness (CCT US) and intraocular pressure measured with Goldmann applanation tonometry (IOP GA). Bordeaux 2 University, Ophthalmology Department, Bordeaux, France. This study comprised 498 eyes of 258 patients. Corneal hysteresis, corneal resistance factor (CRF), and IOP corneal-compensated (IOPcc) were provided by the ORA device; CCT US and IOP GA were also measured in each eye. The study population was divided into 5 groups: normal (n = 122), glaucoma (n = 159), keratoconus (n = 88), laser in situ keratomileusis (LASIK) (n = 78), and photorefractive keratectomy (n = 39). The Pearson correlation was used for statistical analysis. Corneal hysteresis was not strongly correlated with IOP or CCT US. The mean CH in the LASIK (8.87 mm Hg) and keratoconus (8.34 mm Hg) groups was lower than in the glaucoma (9.48 mm Hg) and normal (10.26 mm Hg) groups. The lower the CH, the lower its correlation with IOPcc and IOP GA. A CH higher than the CRF was significantly associated with the keratoconus and post-LASIK groups. Corneal hysteresis, a new corneal parameter, had a moderate dependence on IOP and CCT US. Weaker corneas could be screened with ORA parameters, and low CH could be considered a risk factor for underestimation of IOP. The CCT US should continue to be considered a useful parameter.

  13. Changes in corneal hysteresis after clear corneal cataract surgery.

    Science.gov (United States)

    Hager, Annette; Loge, Kristina; Füllhas, Marc-Oliver; Schroeder, Bernd; Grossherr, Martin; Wiegand, Wolfgang

    2007-09-01

    To assess the changes in corneal hysteresis (CH) as measured by the Ocular Response Analyzer (ORA; Reichert Ophthalmic Instruments, Buffalo, New York, USA) to describe the influence of clear corneal cataract surgery on corneal viscoelastic properties and intraocular pressure (IOP) measured by noncontact tonometry (NCT) and Goldmann applanation tonometry (GAT). Retrospective, interventional, comparative study. One hundred and one eyes of 101 consecutive patients who underwent routine clear corneal cataract surgery were evaluated. CH, NCT, and central corneal thickness (CCT) were measured by ORA before surgery and at postoperative day 1. A control group of 48 pseudophakic eyes (surgery >3 months previously) was included. CCT increased from 556.82 +/- 32.5 microm before surgery to 580.26 +/- 45.5 microm after surgery (P corneal cataract surgery, CH is diminished, whereas CCT is increased significantly. Postoperative corneal edema leads to a change of corneal viscoelastic properties, resulting in a lower damping capacity of the cornea. It is supposed that GAT and NCT measurements are significantly different because of postoperative changes in viscoelastic properties of the cornea.

  14. Collagens and proteoglycans of the corneal extracellular matrix

    Directory of Open Access Journals (Sweden)

    Y.M. Michelacci

    2003-08-01

    Full Text Available The cornea is a curved and transparent structure that provides the initial focusing of a light image into the eye. It consists of a central stroma that constitutes 90% of the corneal depth, covered anteriorly with epithelium and posteriorly with endothelium. Its transparency is the result of the regular spacing of collagen fibers with remarkably uniform diameter and interfibrillar space. Corneal collagen is composed of heterotypic fibrils consisting of type I and type V collagen molecules. The cornea also contains unusually high amounts of type VI collagen, which form microfibrillar structures, FACIT collagens (XII and XIV, and other nonfibrillar collagens (XIII and XVIII. FACIT collagens and other molecules, such as leucine-rich repeat proteoglycans, play important roles in modifying the structure and function of collagen fibrils.Proteoglycans are macromolecules composed of a protein core with covalently linked glycosaminoglycan side chains. Four leucine-rich repeat proteoglycans are present in the extracellular matrix of corneal stroma: decorin, lumican, mimecan and keratocan. The first is a dermatan sulfate proteoglycan, and the other three are keratan sulfate proteoglycans. Experimental evidence indicates that the keratan sulfate proteoglycans are involved in the regulation of collagen fibril diameter, and dermatan sulfate proteoglycan participates in the control of interfibrillar spacing and in the lamellar adhesion properties of corneal collagens. Heparan sulfate proteoglycans are minor components of the cornea, and are synthesized mainly by epithelial cells. The effect of injuries on proteoglycan synthesis is discussed.

  15. Biosynthetic corneal implants for replacement of pathologic corneal tissue: performance in a controlled rabbit alkali burn model.

    Science.gov (United States)

    Hackett, Joanne M; Lagali, Neil; Merrett, Kimberley; Edelhauser, Henry; Sun, Yifei; Gan, Lisha; Griffith, May; Fagerholm, Per

    2011-02-03

    To evaluate the performance of structurally reinforced, stabilized recombinant human collagen-phosphorylcholine (RHCIII-MPC) hydrogels as corneal substitutes in a rabbit model of severe corneal damage. One eye each of 12 rabbits received a deep corneal alkali wound. Four corneas were implanted with RHCIII-MPC hydrogels. The other eight control corneas were implanted with either allografts or a simple cross-linked RHCIII hydrogel. In all cases, 6.25 mm diameter, 350 μm thick buttons were implanted by anterior lamellar keratoplasty to replace damaged corneal tissue. Implants were followed for nine months by clinical examination and in vivo confocal microscopy, after which implanted corneas were removed and processed for histopathological and ultrastructural examination. Alkali exposure induced extensive central corneal scarring, ocular surface irregularity, and neovascularization in one case. All implants showed complete epithelial coverage by four weeks postoperative, but with accompanying suture-induced vascularization in 6 out of 12 cases. A stable, stratified epithelium with hemidesmosomal adhesion complexes regenerated over all implants, and subbasal nerve regeneration was observed in allograft and RHCIII-MPC implants. Initially acellular biosynthetic implants were populated with host-derived keratocytes as stromal haze subsided and stromal collagen was remodeled. Notably, RHCIII-MPC implants exhibited resistance to vascular ingrowth while supporting endogenous cell and nerve repopulation. Biosynthetic implants based on RHC promoted cell and nerve repopulation in alkali burned rabbit eyes. In RHCIII-MPC implants, evidence of an enhanced resistance to neovascularization was additionally noted.

  16. Corneal inflammation is inhibited by the LFA-1 antagonist, lifitegrast (SAR 1118).

    Science.gov (United States)

    Sun, Yan; Zhang, Rui; Gadek, Thomas R; O'Neill, Charles A; Pearlman, Eric

    2013-05-01

    Sterile corneal infiltrates can cause pain, blurred vision, and ocular discomfort in silicone hydrogel contact-lens users. The current study investigates the potential for the synthetic lymphocyte functional antigen-1 (LFA-1) antagonist lifitegrast (SAR 1118) to block corneal inflammation using a murine model. The role of LFA-1 (CD11a/CD18) was examined either in CD18(-/-) mice, by intraperitoneal injection of anti-CD11a, or by topical application of lifitegrast. Corneal inflammation was induced by epithelial abrasion and exposure to either tobramycin-killed Pseudomonas aeruginosa or Staphylococcus aureus in the presence of a 2-mm-diameter punch from a silicone hydrogel contact lens. After 24 h, corneal thickness and haze were examined by in vivo confocal microscopy, and neutrophil recruitment to the corneal stroma was detected by immunohistochemistry. Neutrophil recruitment to the corneal stroma and development of stromal haze were significantly impaired in CD18(-/-) mice or after injection of anti-CD11a. Topical lifitegrast also inhibited P. aeruginosa- and S. aureus-induced inflammation, with the optimal application being a 1% solution applied either 2 or 3 times prior. As LFA-1-dependent neutrophil recruitment to the corneal stroma can be blocked by topical lifitegrast, this reagent could be used in combination with antibiotics to prevent leukocyte infiltration to the corneal stroma in association with contact-lens wear.

  17. Effect of spectacle and contact lenses on the effective corneal refractive zone.

    Science.gov (United States)

    Harris, William F

    2009-03-01

    The effective corneal refractive zone is that portion of the cornea traversed by the light that enters the pupil of the eye from object points at a specified angle from the line of sight. It is of relevance in corneal surgery and for understanding the effect of corneal opacities and lesions on vision. Gaussian optics is used in this paper to obtain explicit equations for the geometry of the effective corneal refractive zone for a simplified eye, when spectacle and contact lenses are worn. The theory shows that lenses of positive power increase the diameter of the effective corneal refractive zone and lenses of negative power decrease the diameter. For axial object points the diameter of the effective corneal refractive zone increases by about 0.015 mm per dioptre increase in the power of the spectacle or contact lens. For object points at 30 degrees from the longitudinal axis, the increase is about twice as much in the case of contact lenses and more than four times as much in the case of spectacle lenses.

  18. Role of corneal collagen fibrils in corneal disorders and related pathological conditions

    Directory of Open Access Journals (Sweden)

    Hong-Yan Zhou

    2017-05-01

    Full Text Available The cornea is a soft tissue located at the front of the eye with the principal function of transmitting and refracting light rays to precisely sense visual information. Corneal shape, refraction, and stromal stiffness are to a large part determined by corneal fibrils, the arrangements of which define the corneal cells and their functional behaviour. However, the modality and alignment of native corneal collagen lamellae are altered in various corneal pathological states such as infection, injury, keratoconus, corneal scar formation, and keratoprosthesis. Furthermore, corneal recuperation after corneal pathological change is dependent on the balance of corneal collagen degradation and contraction. A thorough understanding of the characteristics of corneal collagen is thus necessary to develop viable therapies using the outcome of strategies using engineered corneas. In this review, we discuss the composition and distribution of corneal collagens as well as their degradation and contraction, and address the current status of corneal tissue engineering and the progress of corneal cross-linking.

  19. Topographic corneal changes after collagen cross-linking in patients with corneal keratoconus

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    Hasan Razmjoo

    2013-01-01

    Full Text Available Background: Corneal collagen cross-linking with riboflavin, also known as collagen cross-linking (CXL, involves the application of riboflavin solution to the eye that is activated by illumination with ultraviolet A (UVA light. We survey here the topographic corneal changes one year after CXL in patients with corneal keratoconus. Materials and Methods: This prospective randomized clinical trial study comprised 66 patients with progression of keratoconus during one year who were enrolled at Feiz University Referral Eye Center in Isfahan. Before and after the operation, patients were examined with slit lamp and funduscopic examinations and measurement of uncorrected visual acuity (UCVA, and best spectacle-corrected visual acuity (BSCVA was done with a logarithm of minimal angle of resolution (logMAR scale. Corneal topographic and pachymetry values were derived from Orbscan II. The paired t-test test was used for statistical analyses with SPSS software version 20 (SPSS Inc., Chicago, IL, USA. Results: All 66 patients completed postoperative follow-up at 12 months. The mean age of the patients was 22.4 ± 5.4 years (range: 18-29 years. Thirty-six (54.55% subjects were men and 30 (45.45% were women. The mean preoperative sphere was −2.66 ± 2.14 diopter (D, the mean cylinder was −3.97 ± 2.29, and the mean spherical equivalent (SE was −4.64 ± 2.56. Postoperatively, the mean sphere was −2.22 ± 2.57 D, the mean cylinder was −3.60 ± 2.40 D, and SE was −4.02 ± 2.93 D (P = 0.037. SE also demonstrated a mean difference of 0.62 ± 0.37 D significantly (P = 0.006.The mean diameter of preoperative posterior best-fit sphere (BFS was 6.33 ± 0.35mm (range: 5.51-7.73 mm before operation, and it improved to 6.28 ± 0.34mm (range: 4.36-6.13 mm after operation; the difference was significant (P = 0.039. Conclusion: Our study showed a significant improvement in topographic corneal changes and refractive results in patients with corneal ectasia after

  20. Corneal structure and transparency

    Science.gov (United States)

    Meek, Keith M.; Knupp, Carlo

    2015-01-01

    The corneal stroma plays several pivotal roles within the eye. Optically, it is the main refracting lens and thus has to combine almost perfect transmission of visible light with precise shape, in order to focus incoming light. Furthermore, mechanically it has to be extremely tough to protect the inner contents of the eye. These functions are governed by its structure at all hierarchical levels. The basic principles of corneal structure and transparency have been known for some time, but in recent years X-ray scattering and other methods have revealed that the details of this structure are far more complex than previously thought and that the intricacy of the arrangement of the collagenous lamellae provides the shape and the mechanical properties of the tissue. At the molecular level, modern technologies and theoretical modelling have started to explain exactly how the collagen fibrils are arranged within the stromal lamellae and how proteoglycans maintain this ultrastructure. In this review we describe the current state of knowledge about the three-dimensional stromal architecture at the microscopic level, and about the control mechanisms at the nanoscopic level that lead to optical transparency. PMID:26145225

  1. Tissue Engineering of Corneal Endothelium

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    Satoru Yamagami

    2012-10-01

    Full Text Available Human corneal endothelial cells (HCECs do not replicate after wounding. Therefore, corneal endothelial deficiency can result in irreversible corneal edema. Descemet stripping automated endothelial keratoplasty (DSAEK allows selective replacement of the diseased corneal endothelium. However, DSAEK requires a donor cornea and the worldwide shortage of corneas limits its application. This review presents current knowledge on the tissue engineering of corneal endothelium using cultured HCECs. We also provide our recent work on tissue engineering for DSAEK grafts using cultured HCECs. We reconstructed DSAEK grafts by seeding cultured DiI-labelled HCECs on collagen sheets. Then HCEC sheets were transplanted onto the posterior stroma after descemetorhexis in the DSAEK group. Severe stromal edema was detected in the control group, but not in the DSAEK group throughout the observation period. Fluorescein microscopy one month after surgery showed numerous DiI-labelled cells on the posterior corneal surface in the DSAEK group. Frozen sections showed a monolayer of DiI-labelled cells on Descemet’s membrane. These findings indicate that cultured adult HCECs, transplanted with DSAEK surgery, maintain corneal transparency after transplantation and suggest the feasibility of performing DSAEK with HCECs to treat endothelial dysfunction.

  2. Corneal Confocal Microscopy Detects Corneal Nerve Damage in Patients Admitted With Acute Ischemic Stroke.

    Science.gov (United States)

    Khan, Adnan; Akhtar, Naveed; Kamran, Saadat; Ponirakis, Georgios; Petropoulos, Ioannis N; Tunio, Nahel A; Dargham, Soha R; Imam, Yahia; Sartaj, Faheem; Parray, Aijaz; Bourke, Paula; Khan, Rabia; Santos, Mark; Joseph, Sujatha; Shuaib, Ashfaq; Malik, Rayaz A

    2017-11-01

    Corneal confocal microscopy can identify corneal nerve damage in patients with peripheral and central neurodegeneration. However, the use of corneal confocal microscopy in patients presenting with acute ischemic stroke is unknown. One hundred thirty patients (57 without diabetes mellitus [normal glucose tolerance], 32 with impaired glucose tolerance, and 41 with type 2 diabetes mellitus) admitted with acute ischemic stroke, and 28 age-matched healthy control participants underwent corneal confocal microscopy to quantify corneal nerve fiber density, corneal nerve branch density, and corneal nerve fiber length. There was a significant reduction in corneal nerve fiber density, corneal nerve branch density, and corneal nerve fiber length in stroke patients with normal glucose tolerance ( P stroke. Corneal confocal microscopy is a rapid noninvasive ophthalmic imaging technique that identifies corneal nerve fiber loss in patients with acute ischemic stroke. © 2017 American Heart Association, Inc.

  3. Contact lens fitting following corneal graft surgery.

    Science.gov (United States)

    Szczotka, Loretta B; Lindsay, Richard G

    2003-07-01

    Contact lens fitting may be required following keratoplasty for either optical or therapeutic reasons. Optical indications for contact lens fitting include the correction of irregular astigmatism, high regular astigmatism, anisometropia and secondary aniseikonia, as well as simple ametropia, where the patient desires to wear contact lenses in preference to spectacles. Therapeutic lenses are not routinely fitted following keratoplasty, although this management is advised in certain cases, such as when there are protruding sutures or epithelial healing is impaired. Designing a contact lens for a patient who has undergone keratoplasty will require the practitioner to carefully assess all the relevant features of the corneal graft. In this regard, there are many factors that need to be considered including the diameter of the graft zone, the topographical relationship between the host cornea and donor cornea, the corneal (graft) toricity and the location of the graft. Special designs, such as reverse geometry lenses, or more complex contact lens modalities, such as piggyback contact lens systems, may be required to achieve success in fitting.

  4. Corneal Biomechanical Findings in Contact Lens Induced Corneal Warpage

    OpenAIRE

    Fateme Alipour; Mojgan Letafatnejad; Amir Hooshang Beheshtnejad; Seyed-Farzad Mohammadi; Seyed Reza Ghaffary; Narges Hassanpoor; Mehdi Yaseri

    2016-01-01

    Purpose. To evaluate the difference in biomechanical properties between contact lens induced corneal warpage and normal and keratoconic eyes. Method. Prospective observational case control study, where 94 eyes of 47 warpage suspicious and 46 eyes of 23 keratoconic patients were included. Warpage suspected cases were followed until a definite diagnosis was made (warpage, normal, or keratoconus). Results. 44 eyes of 22 patients had contact lens related corneal warpage. 46 eyes of 23 people were...

  5. Intrastromal Corneal Ring Implants for Corneal Thinning Disorders

    Science.gov (United States)

    2009-01-01

    Executive Summary Objective The purpose of this project was to determine the role of corneal implants in the management of corneal thinning disease conditions. An evidence-based review was conducted to determine the safety, effectiveness and durability of corneal implants for the management of corneal thinning disorders. The evolving directions of research in this area were also reviewed. Subject of the Evidence-Based Analysis The primary treatment objectives for corneal implants are to normalize corneal surface topography, improve contact lens tolerability, and restore visual acuity in order to delay or defer the need for corneal transplant. Implant placement is a minimally invasive procedure that is purported to be safe and effective. The procedure is also claimed to be adjustable, reversible, and both eyes can be treated at the same time. Further, implants do not limit the performance of subsequent surgical approaches or interfere with corneal transplant. The evidence for these claims is the focus of this review. The specific research questions for the evidence review were as follows: Safety Corneal Surface Topographic Effects: Effects on corneal surface remodelling Impact of these changes on subsequent interventions, particularly corneal transplantation (penetrating keratoplasty [PKP]) Visual Acuity Refractive Outcomes Visual Quality (Symptoms): such as contrast vision or decreased visual symptoms (halos, fluctuating vision) Contact lens tolerance Functional visual rehabilitation and quality of life Patient satisfaction: Disease Process: Impact on corneal thinning process Effect on delaying or deferring the need for corneal transplantation Clinical Need: Target Population and Condition Corneal ectasia (thinning) comprises a range of disorders involving either primary disease conditions such as keratoconus and pellucid marginal corneal degeneration or secondary iatrogenic conditions such as corneal thinning occurring after LASIK refractive surgery. The condition

  6. [Transplantation of corneal endothelial cells].

    Science.gov (United States)

    Amano, Shiro

    2002-12-01

    Though conventional corneal transplantation has achieved great success, it still has several drawbacks including limited availability of donor corneas, recurrent allograft rejection, and subsequent graft failure in certain cases. Reconstructing clinically usable corneas by applying the technology of regenerative medicine can offer a solution to these problems, as well as making corneal transplantation a non-emergency surgery and enabling the usage of banked corneal cells. In the present study, we focused on corneal endothelium that is critical for corneal transparency and investigated the reconstruction of cornea utilizing cultured human corneal endothelial cells (HCECs). We succeeded in steadily culturing HCECs by using culture dishes pre-coated with extracellular matrix produced by calf corneal endothelial cells and culture media that contained basic fibroblast growth factor and fetal bovine serum. We performed the following analysis utilizing these cultured HCECs. The older the donor was, the more frequently large senescent cells appeared in the passaged HCECs. The telomeres of HCECs were measured as terminal restriction fragments (TRF) by Southern blotting. HCECs, in vivo from donors in their seventies had a long TRFs of over 12 kilobases. Passaging shortened the TRFs but there was no difference in TRFs among donors of various ages. These results indicated that shortening of telomere length is not related to senescence of HCECs. We investigated the role of advanced glycation end products (AGEs) in the senescence of in vivo HCECs. The results indicated that AGE-protein in the aqueous humor is endocytosed into HCECs via AGE receptors expressed on the surface of HCECs and damages HCECs by producing reactive oxygen species and inducing apoptosis, suggesting that AGEs, at least partly, cause the senescence of HECEs. HCECs were cultured using adult human serum instead of bovine serum to get rid of bovine material that can be infected with prions. Primary and passage

  7. [Corneal collagen cross-linking for keratoconus].

    Science.gov (United States)

    Zotov, V V; Pashtaev, N P; Pozdeeva, N A

    2015-01-01

    Over the last decade, corneal collagen cross-linking (CXL) has become a conventional treatment method for progressive keratoconus. Laboratory studies have shown that CXL increases the diameter of collagen fibers and also the number of intra- and interfibrillar cross-links, thus, increasing biomechanical strength of the irradiated cornea. As confirmed by a series of clinical and randomized controlled trials, CXL is able to slow down and, perhaps, to stop the progression of keratoconus. In most post-CXL patients visual acuity improves, while keratometric readings, spherical equivalent, and higher order aberrations reduce. Although published results prove CXL effective in the treatment of progressive keratoconus, its late consequences are yet unknown. This article reviews the stages of CXL development and results of published experimental and clinical studies. Prospects for CXL modifications that do not require epithelial debridement are discussed.

  8. Corneal epithelium following penetrating keratoplasty.

    OpenAIRE

    Tsubota, K; Mashima, Y; Murata, H; Yamada, M.; Sato, N.

    1995-01-01

    AIMS--This study was designed to observe any changes to the corneal epithelium after penetrating keratoplasty. METHODS--The corneal epithelia of 26 patients were observed by specular microscopy 1 week, 1 month, 3 months, and 6 months following penetrating keratoplasty. RESULTS--After re-epithelialisation was confirmed by biomicroscopy 1 week after surgery, specular microscopy revealed many abnormal cells, including spindle shaped cells, nucleated cells, large cells, as well as irregular cell ...

  9. [Results of tectonic epikeratoplasty in the management of corneal perforations].

    Science.gov (United States)

    Machowicz-Matejko, Eulalia; Rakowska, Ewa; Zagórski, Zbigniew

    2010-01-01

    To present therapeutic application of tectonic epikeratoplasty as logical patch in severe ocular surface disorders. Full thickness corneo-scleral transplants, 14 mm in diameter were used in 67 operations of 41 patients with corneal perforation or descemetocele. (14 women and 27 men), in the period 1998-2008. The mean age of patients was 55.2 +/- 17.7 years (range 15-82). The transplants were sutured over the limbus or the scleral rim and was implanted under the conjunctiva after 360 degrees peritomy. Donor tissue unsuitable for penetrating keratoplasty because of poor endothelium or corneal scarring, was obtained from Lublin Eye Bank. We observed closing of the perforation in all cases. Healing of the ulceration with scar formation and new vessels ingrowth was noted. In some eyes repeated epikeratoplasties were performed. Tectonic epikeratoplasty is a safe and simple method of treatment of corneal perforations. It provides a biological patch stimulating the healing of corneal defects. It gives time for systemic treatment before further ocular surface reconstructive procedures can be performed.

  10. Corneal Topographic Changes After Eyelid Ptosis Surgery.

    Science.gov (United States)

    Savino, Gustavo; Battendieri, Remo; Riso, Monica; Traina, Salvatore; Poscia, Andrea; DʼAmico, Giovanni; Caporossi, Aldo

    2016-04-01

    To evaluate the corneal topography and the topographic changes after ptosis surgery on patients affected by congenital and acquired blepharoptosis. Twenty eyes of 17 patients affected by acquired and congenital ptosis underwent surgical correction through anterior levator complex tightening. Computerized tomography (Syrius Sistem; CSO) was used to analyze any change in corneal astigmatism (CYL), simulated keratometry, anterior corneal symmetry index front, apical keratometry front, and central corneal thickness. Visual acuity, margin reflex distance, and levator function were also measured. After surgical ptosis repair, corneal topography demonstrated a reduction in average keratometry of 0.15 ± 0.47 diopters (D) and in corneal astigmatism of 0.26 ± 1.12 D. Significant differences were found in apical keratometry front (-1.84 ± 1.76 D) and in best-corrected visual acuity (-0.18 ± 0.06 logMAR) in the postoperative examinations. Central corneal thickness did not show significant differences between preoperative and postoperative examinations. Postoperative topographic maps showed a reduction of symmetry index front (0.10 ± 0.64 D). Eyelid ptosis modifies anterior corneal surface inducing refractive errors and modifying corneal astigmatism in patients, thus affecting the quality of vision. The surgical correction of blepharoptosis induces anterior corneal surface modification, restoring corneal symmetry and regular corneal astigmatism. Postoperative corneal topography showed normal corneal contours.

  11. Paradigm shifts in corneal transplantation.

    Science.gov (United States)

    Tan, Donald T H; Anshu, Arundhati; Mehta, Jodhbir S

    2009-04-01

    Conventional corneal transplantation, in the form of penetrating keratoplasty (PK), involves full-thickness replacement of the cornea, and is a highly successful procedure. However, the cornea is anatomically a multi-layered structure. Pathology may only affect individual layers of the cornea, hence selective lamellar surgical replacement of only the diseased corneal layers whilst retaining unaffected layers represents a new paradigm shift in the field. Recent advancements in surgical techniques and instrumentation have resulted in several forms of manual, microkeratome and femto-second laser-assisted lamellar transplantation procedures. Anterior lamellar keratoplasty (ALK) aims at replacing only diseased or scarred corneal stroma, whilst retaining the unaffected corneal endothelial layer, thus obviating the risk of endothelial allograft rejection. Posterior lamellar keratoplasty/endothelial keratoplasty (PLK/EK) involves the replacement of the dysfunctional endothelial cell layer only. Whilst significant technical and surgical challenges are involved in performing lamellar micro-dissection of a tissue which is only 0.5 mm thick, the benefits of a more controlled surgical procedure and improved graft survival rates have resulted in a shift away from conventional PK. This review details the current advances in emerging lamellar corneal surgical procedures and highlights the main advantages and disadvantages of these new lamellar corneal procedures.

  12. Corneal topography in cataract surgery.

    Science.gov (United States)

    Martinez, C E; Klyce, S D

    1996-02-01

    Keratometry and corneal topography remain the most important means of evaluating induced corneal changes after surgery and have comparable sensitivities in the paracentral region of the cornea. However, keratometry gives no information about the peripheral cornea or about asymmetry of the cornea. Videokeratography should be performed after cataract surgery in cases in which best-corrected visual acuity is not adequate and there are no other obvious causes for poor vision to determine whether corneal irregularities are present. The recent literature on corneal topographic evaluation of induced astigmatism after cataract surgery suggests that in general, smaller, temporal incisions result in less astigmatism. Preoperatively, corneal topography can be used in the calculation of intraocular lens power as well as incision planning. Postoperatively, it can be used to detect tight sutures, torsion of the wound, internal wound gape, and irregular astigmatism, as well as to guide suture removal. In the future, corneal topography will become increasingly important in the determination of intraocular lens power in difficult cases such as patients undergoing combined cataract extraction and penetrating keratoplasty as well as patients with a history of radial keratotomy or photorefractive surgery.

  13. CONTACT LENS RELATED CORNEAL ULCER

    Directory of Open Access Journals (Sweden)

    AGARWAL P

    2010-01-01

    Full Text Available A corneal ulcer caused by infection is one of the major causes of blindness worldwide. One of the recent health concerns is the increasing incidence of corneal ulcers associated with contact lens user especially if the users fail to follow specific instruction in using their contact lenses. Risk factors associated with increased risk of contact lens related corneal ulcers are:overnight wear, long duration of continuous wear, lower socio-economic classes, smoking, dry eye and poor hygiene. The presenting symptoms of contact lens related corneal ulcers include eye discomfort, foreign body sensation and lacrimation. More serious symptoms are redness (especially circum-corneal injection, severe pain, photophobia, eye discharge and blurring of vision. The diagnosis is established by a thorough slit lamp microscopic examination with fluorescein staining and corneal scraping for Gram stain and culture of the infective organism. Delay in diagnosing and treatment can cause permanent blindness, therefore an early referral to ophthalmologist and commencing of antimicrobial therapy can prevent visual loss.

  14. Corneal wound healing after excimer laser keratectomy.

    Science.gov (United States)

    Kaji, Yuichi; Yamashita, Hidetoshi; Oshika, Tetsuro

    2003-03-01

    Excimer laser keratectomy is widely used to correct refractive errors. Several complications of excimer laser keratectomy are reported including corneal infection, regression, corneal haze formation, glare and halo. Most of the complications are closely related to the corneal stromal wound healing process. In order to perform the excimer laser keratectomy with minimum complications, we should understand the mechanism of the corneal stroma wound healing process. In addition, such knowledge will help us to regulate the corneal stromal wound healing process in the future. In the present article, we discuss the molecular mechanism of the corneal stromal wound healing process after excimer laser keratectomy and its regulation by anti-inflammatory agents.

  15. Corneal thickness changes after corneal collagen crosslinking for keratoconus and corneal ectasia: one-year results.

    Science.gov (United States)

    Greenstein, Steven A; Shah, Vinnie P; Fry, Kristen L; Hersh, Peter S

    2011-04-01

    To determine the changes in corneal thickness over time after corneal collagen crosslinking (CXL) for keratoconus and corneal ectasia. Cornea and refractive surgery subspecialty practice. Prospective randomized controlled clinical trial. Corneal thickness at the apex, thinnest point, and pupil center were measured using Scheimpflug imaging (Pentacam) at baseline and 1, 3, 6, and 12 months after CXL. The treatment group was compared with both a sham-procedure control group and a fellow-eye control group. Associations with clinical outcomes (uncorrected and corrected distance visual acuities and maximum keratometry) were analyzed. The study comprised 82 eyes, 54 with keratoconus and 28 with ectasia after laser in situ keratomileusis. The mean preoperative thinnest pachymetry was 440.7 μm ± 52.9 (SD). After CXL, the cornea thinned at 1 month (mean change -23.8 ± 28.7 μm; Pdegree of corneal thinning at 3 months and clinical outcomes after CXL. After CXL, the cornea thins and then recovers toward baseline thickness. The cause and implications of corneal thickness changes after CXL remain to be elucidated. No author has a financial or proprietary interest in any material or method mentioned. Additional disclosure is found in the footnotes. Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  16. Corneal stromal dystrophies: a clinical pathologic study

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    Elvira Barbosa Abreu

    2012-12-01

    Full Text Available INTRODUCTION: Corneal dystrophy is defined as bilateral and symmetric primary corneal disease, without previous associated ocular inflammation. Corneal dystrophies are classified according to the involved corneal layer in superficial, stromal, and posterior dystrophy. Incidence of each dystrophy varies according to the geographic region studied. PURPOSE: To evaluate the prevalence of stromal corneal dystrophies among corneal buttons specimens obtained by penetrating keratoplasty (PK in an ocular pathology laboratory and to correlate the diagnosis with patient age and gender. METHODS: Corneal button cases of penetrating keratoplasty from January-1996 to May-2009 were retrieved from the archives of The Henry C. Witelson Ophthalmic Pathology Laboratory and Registry, Montreal, Canada. The cases with histopathological diagnosis of stromal corneal dystrophies were stained with special stains (Peroxid acid Schiff, Masson trichrome, Congo red analyzed under polarized light, and alcian blue for classification and correlated with epidemiological information (age at time of PK and gender from patients' file. RESULTS: 1,300 corneal buttons cases with clinical diagnose of corneal dystrophy were retrieved. Stromal corneal dystrophy was found in 40 (3.1% cases. Lattice corneal dystrophy was the most prevalent with 26 cases (65%. Nineteen were female (73.07% and the PK was performed at average age of 59.3 years old. Combined corneal dystrophy was found in 8 (20% cases, 5 (62.5% of them were female and the average age of the penetrating keratoplasty was 54.8 years old. Granular corneal dystrophy was represented by 5 (12.5% cases, and 2 (40% of them were female. Penetrating keratoplasty was performed at average age of 39.5 years old in granular corneal dystrophy cases. Macular corneal dystrophy was present in only 1 (2.5% case, in a 36 years old female. CONCLUSION: Systematic histopathological approach and evaluation, including special stains in all stromal

  17. Corneal Sparing Conjunctival Abrasion

    Directory of Open Access Journals (Sweden)

    Hamid Ehsani-Nia

    2017-07-01

    Full Text Available History of present illness: A 15-year-old male was transported to the emergency department via ambulance as a trauma activation after being struck by an automobile while jogging. Patient was alert and oriented, with no focal neurological deficits and no loss of consciousness. The patient complained of right eye foreign body sensation. Significant findings: Physical exam was significant for multiple broken teeth, multiple minor abrasions on the face, and fine shards of shattered glass on his face and hair. His right eye had conjunctival injection, with no signs of subconjunctival hemorrhage or ocular penetration. Vision, extraocular movement, and pupillary exam were grossly intact. Fluorescein staining with slit lamp exam with cobalt blue filter examination of the right eye revealed superficial bulbar conjunctival uptake of fluorescein dye staining an area of the conjunctiva inferior to the limbus 5 mm vertical by 2 mm horizontal (estimation by photo provided. No foreign bodies were visualized in the inferior fornix. These findings were consistent with superficial conjunctival abrasion. The exam noted sparing of the corneal epithelium. Discussion: The conjunctiva is a thin, transparent membrane covering the ocular surface from the corneal limbus to the posterior eyelid margin.1 When damaged, the patient will classically have a “foreign body” sensation. It is important to identify the extent of the injury as not extending over the cornea, and also to search for lodged foreign bodies that damage the conjunctiva further with each blink. Classically retained foreign bodies will form a linear and vertical pattern of staining with fluorescein.2,3 Fluorescein stains expose basement membrane and fluoresces bright green under ultraviolet light, thus indicating areas of damage in contrast to its surrounding tissue.4,5 In the setting of acute trauma, urgent Ophthalmologic consultation is indicated if there is anterior chamber hemorrhage, a ruptured or

  18. Central corneal thickness and corneal hysteresis associated with glaucoma damage.

    Science.gov (United States)

    Congdon, Nathan G; Broman, Aimee T; Bandeen-Roche, Karen; Grover, Davinder; Quigley, Harry A

    2006-05-01

    We sought to measure the impact of central corneal thickness (CCT), a possible risk factor for glaucoma damage, and corneal hysteresis, a proposed measure of corneal resistance to deformation, on various indicators of glaucoma damage. Observational study. Adult patients of the Wilmer Glaucoma Service underwent measurement of hysteresis on the Reichert Ocular Response Analyzer and measurement of CCT by ultrasonic pachymetry. Two glaucoma specialists (H.A.Q., N.G.C.) reviewed the chart to determine highest known intraocular pressure (IOP), target IOP, diagnosis, years with glaucoma, cup-to-disk ratio (CDR), mean defect (MD), pattern standard deviation (PSD), glaucoma hemifield test (GHT), and presence or absence of visual field progression. Among 230 subjects, the mean age was 65 +/- 14 years, 127 (55%) were female, 161 (70%) were white, and 194 (85%) had a diagnosis of primary open-angle glaucoma (POAG) or suspected POAG. In multivariate generalized estimating equation models, lower corneal hysteresis value (P = .03), but not CCT, was associated with visual field progression. When axial length was included in the model, hysteresis was not a significant risk factor (P = .09). A thinner CCT (P = .02), but not hysteresis, was associated with a higher CDR at the most recent examination. Neither CCT nor hysteresis was associated with MD, PSD, or GHT "outside normal limits." Thinner CCT was associated with the state of glaucoma damage as indicated by CDR. Axial length and corneal hysteresis were associated with progressive field worsening.

  19. The DIAMET campaign

    Science.gov (United States)

    Vaughan, G.

    2012-04-01

    DIAMET (DIAbatic influences on Mesoscale structures in ExTratropical storms) is a joint project between the UK academic community and the Met Office. Its focus is on understanding and predicting mesoscale structures in synoptic-scale storms, and in particular on the role of diabatic processes in generating and maintaining them. Such structures include fronts, rain bands, secondary cyclones, sting jets etc, and are important because much of the extreme weather we experience (e.g. strong winds, heavy rain) comes from such regions. The project conducted two field campaigns in the autumn of 2011, from September 14 - 30 and November 24 - December 14, based around the FAAM BAe146 aircraft with support from ground-based radar and radiosonde measurements. Detailed modelling, mainly using the Met Office Unified model, supported the planning and interpretation of these campaigns. This presentation will give a brief overview of the campaigns. Both in September and November-December the weather regime was westerly, with a strong jet stream directed across the Atlantic. Three IOPs were conducted in September, to observe a convective band ahead of an upper-level trough, waves on a long trailing cold front, and a warm conveyor belt associated with a secondary cyclone. In November-December six IOPs were conducted, to observe frontal passages and high winds. This period was notable for a number of very strong windstorms passing across the north of the UK, and gave us an opportunity to examine bent-back warm fronts in the southern quadrant of these storms where the strongest winds are found. The case studies fell into two basic patterns. In the majority of cases, dropsonde legs at high level were used to obtain a cross-section of winds and thermodynamic structure (e.g. across a front), followed by in situ legs at lower levels (generally where the temperature was between 0 and -10°) to examine microphysical processes, especially ice multiplication and the extent of supercooled water

  20. Substrates for Expansion of Corneal Endothelial Cells towards Bioengineering of Human Corneal Endothelium

    Directory of Open Access Journals (Sweden)

    Jesintha Navaratnam

    2015-09-01

    Full Text Available Corneal endothelium is a single layer of specialized cells that lines the posterior surface of cornea and maintains corneal hydration and corneal transparency essential for vision. Currently, transplantation is the only therapeutic option for diseases affecting the corneal endothelium. Transplantation of corneal endothelium, called endothelial keratoplasty, is widely used for corneal endothelial diseases. However, corneal transplantation is limited by global donor shortage. Therefore, there is a need to overcome the deficiency of sufficient donor corneal tissue. New approaches are being explored to engineer corneal tissues such that sufficient amount of corneal endothelium becomes available to offset the present shortage of functional cornea. Although human corneal endothelial cells have limited proliferative capacity in vivo, several laboratories have been successful in in vitro expansion of human corneal endothelial cells. Here we provide a comprehensive analysis of different substrates employed for in vitro cultivation of human corneal endothelial cells. Advances and emerging challenges with ex vivo cultured corneal endothelial layer for the ultimate goal of therapeutic replacement of dysfunctional corneal endothelium in humans with functional corneal endothelium are also presented.

  1. Quiste dermoide corneal bilateral

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    Michel Guerra Almaguer

    Full Text Available El dermoide es un tipo de coristoma (tejido embrionario normal en una localización anormal que afecta con frecuencia la córnea. Aparece como una masa sólida, blanca, redonda y elevada. Suele localizarse en el limbo inferotemporal, aunque puede hacerlo en cualquier lugar del globo ocular o de la órbita. Se presenta un paciente masculino, de 8 años de edad, quien desde su nacimiento muestra una mancha blanca en ambos ojos, agudeza visual sin corrección de movimiento de mano a 33 centímetros en el ojo derecho y percepción luminosa en el ojo izquierdo. En la exploración oftalmológica de ambos ojos se apreciaron lesiones blanquecinas sobre la córnea. Se le realizó exéresis del quiste y queratoplastia lamelar de ambos ojos, con resultados visuales satisfactorios. Se concluye que el caso presenta un quiste dermoide corneal bilateral.

  2. Corneal biomechanics: a review.

    Science.gov (United States)

    Piñero, David P; Alcón, Natividad

    2015-03-01

    Biomechanics is often defined as 'mechanics applied to biology'. Due to the variety and complexity of the behaviour of biological structures and materials, biomechanics is better defined as the development, extension and application of mechanics for a better understanding of physiology and physiopathology and consequently for a better diagnosis and treatment of disease and injury. Different methods for the characterisation of corneal biomechanics are reviewed in detail, including those that are currently commercially available (Ocular Response Analyzer and CorVis ST). The clinical applicability of the parameters provided by these devices are discussed, especially in the fields of glaucoma, detection of ectatic disorders and orthokeratology. Likewise, other methods are also reviewed, such as Brillouin microscopy or dynamic optical coherence tomography and others with potential application to clinical practice but not validated for in vivo measurements, such as ultrasonic elastography. Advantages and disadvantages of all these techniques are described. Finally, the concept of biomechanical modelling is revised as well as the requirements for developing biomechanical models, with special emphasis on finite element modelling. © 2014 The Authors. Clinical and Experimental Optometry © 2014 Optometry Australia.

  3. Femtosecond laser corneal refractive surgery

    Science.gov (United States)

    Kurtz, Ron M.; Spooner, Greg J. R.; Sletten, Karin R.; Yen, Kimberly G.; Sayegh, Samir I.; Loesel, Frieder H.; Horvath, Christopher; Liu, HsiaoHua; Elner, Victor; Cabrera, Delia; Muenier, Marie-Helene; Sacks, Zachary S.; Juhasz, Tibor

    1999-06-01

    We evaluated the efficacy, safety, and stability of femtosecond laser intrastromal refractive procedures in ex vivo and in vivo models. When compared with longer pulsewidth nanosecond or picosecond laser pulses, femtosecond laser-tissue interactions are characterized by significantly smaller and more deterministic photodisruptive energy thresholds, as well as reduced shock waves and smaller cavitation bubbles. We utilized a highly reliable, all-solid-state femtosecond laser system for all studies to demonstrate clinical practicality. Contiguous tissue effects were achieved by scanning a 5 μm focused laser spot below the corneal surface at pulse energies of approximately 2 - 4 microjoules. A variety of scanning patterns was used to perform three prototype procedures in animal eyes; corneal flap cutting, keratomileusis, and intrastromal vision correction. Superior dissection and surface quality results were obtained for lamellar procedures (corneal flap cutting and keratomileusis). Preliminary in vivo evaluation of intrastromal vision correction in a rabbit model revealed consistent and stable pachymetry changes, without significant inflammation or loss of corneal transparency. We conclude that femtosecond laser technology may be able to perform a variety of corneal refractive procedures with high precision, offering advantages over current mechanical and laser devices and techniques.

  4. Corneal complications of vernal keratoconjunctivitis.

    Science.gov (United States)

    Solomon, Abraham

    2015-10-01

    Vernal keratoconjunctivitis (VKC) is a severe bilateral chronic allergic inflammatory disease of the ocular surface. In most of the cases, the disease is limited to the tarsal conjunctiva and to the limbus. However, in the more severe cases, the cornea may be involved, leading to potentially sight threatening complications. Prompt recognition of these complications is crucial in the management of VKC, which is one of the most severe ocular allergic diseases. A vicious cycle of inflammation occurs as a result of a set of reciprocal interactions between the conjunctiva and the cornea, which results in damage to the corneal epithelium and corneal stoma, and to the formation of shield ulcers and plaques, infectious keratitis, keratoconus, scarring, and limbal stem cell deficiency. These corneal complications can cause permanent decrease or loss of vision in children suffering from VKC. Corneal complications in VKC are the result of an on-going process of uncontrolled inflammation. Proper recognition of the corneal complications in VKC is crucial, as most of these can be managed or prevented by a combination of medical and surgical measures.

  5. An accessible approach for corneal topography

    OpenAIRE

    André Luís Beling da Rosa

    2013-01-01

    Corneal topography consists of measuring the corneal shape, which is a key factor for visual acuity. The exam is used, for instance, in keratoconus detection, personalized contact lens fitting, in pre- and post-procedures associated with refractive surgery and corneal transplants. This thesis presents an accessible, inexpensive and portable approach to perform corneal topographies. The results obtained with our prototype show a mean difference of about 0.02 millimeters, equivalent to 0.5% of ...

  6. Progress of research on corneal collagen cross-linking for corneal melting

    Directory of Open Access Journals (Sweden)

    Ke-Ren Xiao

    2016-06-01

    Full Text Available Corneal collagen cross-linking(CXLcould increase the mechanical strength, biological stability and halt ectasia progression due to covalent bond formed by photochemical reaction between ultraviolet-A and emulsion of riboflavin between collagen fibers in corneal stroma. Corneal melting is an autoimmune related noninfectious corneal ulcer. The mechanism of corneal melting, major treatment, the basic fundamental of ultraviolet-A riboflavin induced CXL and the clinical researches status and experiment in CXL were summarized in the study.

  7. Acute corneal hydrops in keratoconus

    Directory of Open Access Journals (Sweden)

    Prafulla K Maharana

    2013-01-01

    Full Text Available Acute corneal hydrops is a condition characterized by stromal edema due to leakage of aqueous through a tear in descemet membrane. The patient presents with sudden onset decrease in vision, photophobia, and pain. Corneal thinning and ectasias combined with trivial trauma to the eye mostly by eye rubbing is considered as the underlying cause. With conservative approach self-resolution takes around 2 to 3 months. Surgical intervention is required in cases of non-resolution of corneal edema to avoid complications and for early visual rehabilitation. Intracameral injection of air or gas such as perflouropropane is the most common surgical procedure done. Recent investigative modality such as anterior segment optical coherence tomography is an extremely useful tool for diagnosis, surgical planning, and postoperative follow up. Resolution of hydrops may improve the contact lens tolerance and visual acuity but most cases require keratoplasty for visual rehabilitation.

  8. [Corneal toxicity due to amantadine].

    Science.gov (United States)

    Avendaño-Cantos, E M; Celis-Sánchez, J; Mesa-Varona, D; Gálvez-Martínez, J; López-Arroquia, E; González Del Valle, F

    2012-09-01

    A 64 year-old female with Parkinson disease treated with amantadine for two years who suddenly suffered bilateral corneal oedema. It was initially treated as herpetic endotheliitis without improvement as we lacked information on her chronic treatment. The corneal oedema finally resolved after withdrawing the drug. Amantadine hydrochloride may produce endothelial dysfunction. Once the amantadine treatment is stopped, the corneal oedema may be reversible but endothelial density remains low. An ophthalmologist examination should be performed before the initiation of amantadine treatment in order to establish a risk: benefit ratio, especially in those patients with low endothelial density or any endothelial anomaly. Copyright © 2011 Sociedad Española de Oftalmología. Published by Elsevier Espana. All rights reserved.

  9. [An analysis of changes in posterior corneal elevation and relevant factors after small incision lenticule extraction].

    Science.gov (United States)

    Yu, C J; Wang, Y; Su, X L; Wu, W J; Wu, Z Q; Wu, Y N

    2016-07-01

    To investigate changes in posterior corneal elevation after small incision lenticule extraction (SMILE) and related factors. Retrospective case series study. Eighty-three eyes of 44 myopic patients undergoing SMILE were examined with the Pentacam preoperatively, and at 1 day, 1 month, 3 months, and 6 months postoperatively. Posterior corneal elevation at the corneal apex and 0°, 45°, 90°, 135°, 180°, 225°, 270° and 325° points of the 2 mm and 6 mm diameter (total, 17 points) was analyzed. The changes in posterior corneal elevation at 1 day, 1 month, 3 months, and 6 months were(-1.72±2.59), (-0.98±2.37), (-0.45±1.81) and (-0.25±2.20) μm, respectively, at the corneal apex. The results were statistically significant (t=6.07, 3.75, 6.07; Pcorneal elevation were (-1.42±2.06),(-0.69±1.86), (-0.30±1.50) and(-0.22±1.58) μm, respectively, in the 2 mm circle. The results of 1 day and 1 month were statistically significant (t=6.28, 6.28, Pcorneal elevation were (1.48±1.47),(0.98±1.32),(0.90±1.31) and (0.90±1.16) μm, respectively, in the 6 mm circle .The results were totally statistically significant (t=6.28, 6.28, Pcorneal apex, 2 mm and 6 mm circles. The changes were (0.75±2.55),(0.73±1.97) and(-0.50±1.60) μm. There were statistically significant differences between 3 months and 1 month postoperatively in the corneal apex and 2 mm circle. The changes were (0.53±2.22) and (0.39±1.80) μm. No significant change was found in the 6 mm circle. Between postoperative 6 months and 3 months, there were no statistically significant differences. The spherical equivalent, intraocular pressure, ablation depth, residual bed thickness, corneal hysteresis, and corneal resistance factor had no obvious correlation with the changes in posterior corneal elevation. After SMILE, the surrounding cornea was slightly forward, while the central posterior cornea was slightly backwards, and returned gradually. The spherical equivalent, intraocular pressure, ablation depth

  10. Posterior Corneal Surface Stability after Femtosecond Laser-Assisted Keratomileusis

    Directory of Open Access Journals (Sweden)

    Carlo Cagini

    2015-01-01

    Full Text Available The purpose of this study was to evaluate posterior corneal surface variation after femtosecond laser-assisted keratomileusis in patients with myopia and myopic astigmatism. Patients were evaluated by corneal tomography preoperatively and at 1, 6, and 12 months. We analyzed changes in the posterior corneal curvature, posterior corneal elevation, and anterior chamber depth. Moreover, we explored correlation between corneal ablation depth, residual corneal thickness, percentage of ablated corneal tissue, and preoperative corneal thickness. During follow-up, the posterior corneal surface did not have a significant forward corneal shift: no significant linear relationships emerged between the anterior displacement of the posterior corneal surface and corneal ablation depth, residual corneal thickness, or percentage of ablated corneal tissue.

  11. Progress in corneal wound healing

    Science.gov (United States)

    Ljubimov, Alexander V.; Saghizadeh, Mehrnoosh

    2015-01-01

    Corneal wound healing is a complex process involving cell death, migration, proliferation, differentiation, and extracellular matrix remodeling. Many similarities are observed in the healing processes of corneal epithelial, stromal and endothelial cells, as well as cell-specific differences. Corneal epithelial healing largely depends on limbal stem cells and remodeling of the basement membrane. During stromal healing, keratocytes get transformed to motile and contractile myofibroblasts largely due to activation of transforming growth factor-β system. Endothelial cells heal mostly by migration and spreading, with cell proliferation playing a secondary role. In the last decade, many aspects of wound healing process in different parts of the cornea have been elucidated, and some new therapeutic approaches have emerged. The concept of limbal stem cells received rigorous experimental corroboration, with new markers uncovered and new treatment options including gene and microRNA therapy tested in experimental systems. Transplantation of limbal stem cell-enriched cultures for efficient re-epithelialization in stem cell deficiency and corneal injuries has become reality in clinical setting. Mediators and course of events during stromal healing have been detailed, and new treatment regimens including gene (decorin) and stem cell therapy for excessive healing have been designed. This is a very important advance given the popularity of various refractive surgeries entailing stromal wound healing. Successful surgical ways of replacing the diseased endothelium have been clinically tested, and new approaches to accelerate endothelial healing and suppress endothelial-mesenchymal transformation have been proposed including Rho kinase (ROCK) inhibitor eye drops and gene therapy to activate TGF-β inhibitor SMAD7. Promising new technologies with potential for corneal wound healing manipulation including microRNA, induced pluripotent stem cells to generate corneal epithelium, and

  12. Patch Grafting Using a Cryopreserved Descemet Stripping Automated Endothelial Keratoplasty Flap for Treating Corneal Perforation

    Directory of Open Access Journals (Sweden)

    Arisa Okada

    2016-04-01

    Full Text Available A 73-year-old woman with a corneal perforation of undetermined etiology was treated with corneal patch grafting. A residual partial-thickness corneal button obtained during a previous Descemet stripping automated endothelial keratoplasty (DSAEK surgery and stored at –80°C in Optisol GS for 3 months was used as a patch graft. Five days postoperatively, the anterior chamber was reformed and the perforation was masked by the donor cornea. During the next several weeks, gradual displacement of the anterior edge of the donor cornea in the limbal direction occurred. Seven weeks postoperatively, further displacement of the donor cornea resulted in unmasking of the perforated area. At this time, the corneal defect was closed by stromal scar tissue and corneal epithelium. Five months postoperatively, best corrected visual acuity was 1.0 without marked astigmatism and intraocular pressure was 9 mm Hg in the left eye. From this case, we learned that cryopreserved DSAEK flaps stored longer than reported previously can be used as patch grafts to treat emergency conditions. Scar tissue can fill a corneal stromal defect 1 mm in diameter during temporary patch grafting for less than 2 months.

  13. Treatment of corneal chemical alkali burns with a crosslinked thiolated hyaluronic acid film.

    Science.gov (United States)

    Griffith, Gina L; Wirostko, Barbara; Lee, Hee-Kyoung; Cornell, Lauren E; McDaniel, Jennifer S; Zamora, David O; Johnson, Anthony J

    2018-02-08

    The study objective was to test the utilization of a crosslinked, thiolated hyaluronic acid (CMHA-S) film for treating corneal chemical burns. Burns 5.5mm in diameter were created on 10 anesthetized, male New Zealand white rabbits by placing a 1N NaOH soaked circular filter paper onto the cornea for 30s. Wounds were immediately rinsed with balanced salt solution (BSS). CMHA-S films were placed in the left inferior fornix of five injured and five uninjured animals. Five animals received no treatment. At 0h, 48h, 96h, and on day 14 post chemical burn creation, eyes were evaluated by white light imaging, fluorescein staining, and optical coherence tomography (OCT). Corneal histology was performed using H&E and Masson's Trichrome stains. Image analysis indicated biocompatible CMHA-S treatment resulted in significant decreases in the areas of corneal opacity at 48h, 96h, and on day 14 postoperatively. A significant increase in re-epithelialization was seen 14days post injury. CMHA-S treated corneas showed significantly less edema than untreated burns. No pathological differences were observed in corneal histological samples as a result of CMHA-S treatment. CMHA-S films facilitate re-epithelialization and decrease the area of corneal opacity in our corneal alkali burn rabbit model. Copyright © 2018 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  14. Keratoconus corneal architecture after riboflavin/ultraviolet A cross-linking: Ultrastructural studies

    Science.gov (United States)

    Almubrad, Turki; Paladini, Iacopo; Mencucci, Rita

    2013-01-01

    Purpose Study to investigate the effects of collagen cross-linking on the ultrastructural organization of the corneal stroma in the human keratoconus cornea (KC). Methods Three normal, three keratoconus (KC1, KC2, KC3), and three cross-linked keratoconus (CXL1, CXL2, CXL3) corneas were analyzed. The KC corneas were treated with a riboflavin-ultraviolet A (UVA) treatment (CXL) method described by Wollensak et al. Penetrating keratoplasty (PKP) was performed 6 months after treatment. All samples were processed for electron microscopy. Results The riboflavin-UVA-treated CXL corneal stroma showed interlacing lamellae in the anterior stroma followed by well-organized parallel running lamellae. The lamellae contained uniformly distributed collagen fibrils (CFs) decorated with normal proteoglycans (PGs). The CF diameter and interfibrillar spacing in the CXL cornea were significantly increased compared to those in the KC cornea. The PG area in the CXL corneas were significantly smaller than the PGs in the KC cornea. The epithelium and Bowman’s layer were also normal. On rare occasions, a thick basement membrane and collagenous pannus were also observed. Conclusions Corneal cross-linking leads to modifications of the cornea stroma. The KC corneal structure showed a modification in the CF diameter, interfibrillar spacing, and PG area. This resulted in a more uniform distribution of collagen fibrils, a key feature for corneal transparency. PMID:23878503

  15. Corneal Thickness as a Predictor of Corneal Transplant Outcome

    Science.gov (United States)

    Verdier, David D.; Sugar, Alan; Baratz, Keith; Beck, Roy; Dontchev, Mariya; Dunn, Steven; Gal, Robin L.; Holland, Edward J.; Kollman, Craig; Lass, Jonathan H.; Mannis, Mark J.; Penta, Jeffrey

    2013-01-01

    Purpose Assess corneal thickness (CT) and correlation with graft outcome after penetrating keratoplasty in the Cornea Donor Study. Methods 887 subjects with a corneal transplant for a moderate risk condition (principally Fuchs or pseudophakic corneal edema) had post-operative CT measurements throughout a 5 year follow up time. Relationships between baseline (recipient, donor, and operative) factors and CT were explored. Proportional hazards models were used to assess association between CT and graft failure. Relationship between CT and cell density was assessed with a longitudinal repeated measures model and Spearman correlation estimates. Results Higher longitudinal CT measurements were associated with diagnosis of pseudophakic or aphakic corneal edema (P 25mmHg during the first post-operative month (P=0.003), white (non-Hispanic) donor race (P=0.002) and respiratory causes of donor death (P600μm. In multivariate analysis, both 1 year CT and cell density were associated with subsequent graft failure (P=0.002 and 0.009). CT increase was modestly associated with endothelial cell loss during follow up (r=-0.29). Conclusion During the first 5 years following penetrating keratoplasty, CT can serve as a predictor of graft survival. However, CT is not a substitute for cell density measurement as both measures were independently predictive of graft failure. PMID:23343949

  16. Wheel Diameter and Speedometer Reading

    Science.gov (United States)

    Murray, Clifton

    2010-01-01

    Most introductory physics students have seen vehicles with nonstandard wheel diameters; some may themselves drive "low-rider" cars or "big-wheel" pickup trucks. But how does changing wheel diameter affect speedometer readout for a given speed? Deriving the answer can be followed readily by students who have been introduced to rotation, and it…

  17. Metalloproteinases in corneal diseases: degradation and processing.

    Science.gov (United States)

    Sakimoto, Tohru; Sawa, Mitsuru

    2012-11-01

    Matrix metalloproteinases (MMPs) are zinc-dependent endopeptidases with the potential to degrade all types of extracellular matrix. The ADAM (a disintegrin and metalloproteinase) family of peptidases was recently identified as cleaving the extracellular domain of transmembrane proteins. This was termed ectodomain shedding. We investigated the MMP expression in patients with corneal diseases and the potential role of ADAMs in corneal pathophysiology. We detected upregulation of the active form of MMP-2 and MMP-9 in the tear fluid from patients with corneal melting or recurrent corneal erosion. Using human corneal epithelial cells, we observed ADAM17-dependent ectodomain shedding of soluble tumor necrosis factor receptor 1 and soluble interleukin-6 (IL-6) receptor (sIL-6R). The production of sIL-6R was also induced by messenger RNA splicing in the human corneal epithelial cells. IL-6/sIL-6R-induced signal transducer and activator of transcription 3 phosphorylation was observed in cultured human corneal fibroblasts, suggesting that IL-6 trans-signaling induced inflammatory cellular signaling in the human corneal fibroblasts. We demonstrated that MMPs are significantly upregulated in collagen-destructive disorders of the cornea. Additionally, we observed that ectodomain shedding by ADAMs in corneal epithelial cells mediated the production of soluble cytokine receptors. Trans-signaling of IL-6 can induce an inflammatory response in corneal stroma, indicating the significance of IL-6 trans-signaling in ocular surface inflammation. Thus, MMPs and ADAMs play an important role in the pathophysiology of corneal diseases.

  18. A portable microkeratome-based anterior corneal surface harvesting device.

    Science.gov (United States)

    Sarayba, Melvin A; Li, Li; Sweet, Paula M; Chuck, Roy S

    2002-08-01

    To determine the reproducibility of anterior sclerokeratectomy using a portable nonelectric microkeratome-based device capable of harvesting the entire anterior corneal surface for lamellar transplantation. A modified gas turbine-driven microkeratome (LSK One, Moria/Microtech, Doylestown, PA) with a redesigned head large enough to incorporate the whole human anterior corneal surface in a pass and was coupled to a manual vacuum pump. This instrument was tested on 25 fresh porcine globes divided into 2 groups (170-microm and 200-microm head). To assess cut reproducibility the physical dimensions (diameter and thickness) of the obtained lenticules were measured. The obtained lenticules were fairly circular (horizontal versus vertical diameters, p >0.2), with average diameters of 12.85 +/- 0.52 mm and 13.25 +/- 1.15 mm for the 170 and 200-microm heads, respectively. The average central lenticule thickness was 176.92 +/- 34.68 microm and 166.00 +/- 53.74 microm for the 170 and 200-microm heads, respectively. This new system presents an economical and portable alternative to electric-powered systems. In addition to being used by surgeons in the operating room, eye bank technicians in the field could theoretically use this system; including in developing countries where cost, availability of electricity, and portability are issues.

  19. Corneal Regeneration After Photorefractive Keratectomy: A Review☆

    Science.gov (United States)

    Tomás-Juan, Javier; Murueta-Goyena Larrañaga, Ane; Hanneken, Ludger

    2014-01-01

    Photorefractive keratectomy (PRK) remodels corneal stroma to compensate refractive errors. The removal of epithelium and the ablation of stroma provoke the disruption of corneal nerves and a release of several peptides from tears, epithelium, stroma and nerves. A myriad of cytokines, growth factors, and matrix metalloproteases participate in the process of corneal wound healing. Their balance will determine if reepithelization and stromal remodeling are appropriate. The final aim is to achieve corneal transparency for restoring corneal function, and a proper visual quality. Therefore, wound-healing response is critical for a successful refractive surgery. Our goal is to provide an overview into how corneal wounding develops following PRK. We will also review the influence of intraoperative application of mitomycin C, bandage contact lenses, anti-inflammatory and other drugs in preventing corneal haze and post-PRK pain. PMID:25444646

  20. Corneal Regeneration After Photorefractive Keratectomy: A Review.

    Science.gov (United States)

    Tomás-Juan, Javier; Murueta-Goyena Larrañaga, Ane; Hanneken, Ludger

    2015-01-01

    Photorefractive keratectomy (PRK) remodels corneal stroma to compensate refractive errors. The removal of epithelium and the ablation of stroma provoke the disruption of corneal nerves and a release of several peptides from tears, epithelium, stroma and nerves. A myriad of cytokines, growth factors, and matrix metalloproteases participate in the process of corneal wound healing. Their balance will determine if reepithelization and stromal remodeling are appropriate. The final aim is to achieve corneal transparency for restoring corneal function, and a proper visual quality. Therefore, wound-healing response is critical for a successful refractive surgery. Our goal is to provide an overview into how corneal wounding develops following PRK. We will also review the influence of intraoperative application of mitomycin C, bandage contact lenses, anti-inflammatory and other drugs in preventing corneal haze and post-PRK pain. Copyright © 2014 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

  1. History of corneal transplantation in Australia.

    Science.gov (United States)

    Coster, Douglas J

    2015-04-01

    Corneal transplantation is a triumph of modern ophthalmology. The possibility of corneal transplantation was first raised in 1797 but a century passed before Zirm achieved the first successful penetrating graft in 1905. Gibson reported the first corneal graft in Australia from Brisbane in 1940 and English established the first eye bank there a few years later. Corneal transplantation evolved steadily over the twentieth century. In the second half of the century, developments in microsurgery, including surgical materials such as monofilament nylon and strong topical steroid drops, accounted for improvements in outcomes. In 2013, approximately 1500 corneal transplants were done in Australia. Eye banking has evolved to cope with the rising demands for donor corneas. Australian corneal surgeons collaborated to establish and support the Australian Corneal Graft Registry in 1985. It follows the outcomes of their surgery and has become an important international resource for surgeons seeking further improvement with the procedure. © 2014 Royal Australian and New Zealand College of Ophthalmologists.

  2. Corneal biomechanical properties in floppy eyelid syndrome.

    Science.gov (United States)

    Muniesa, MaJesús; Muniesa Royo, MaJesús; March, Ana; March de Ribot, Ana; Sánchez-de-la-Torre, Manuel; Huerva, Valetín; Huerva Escanilla, Valetín; Jurjo, Carmen; Jurjo Campo, Carmen; Barbé, Ferran; Barbé Illa, Ferran

    2015-05-01

    To determine corneal biomechanical properties in patients with floppy eyelid syndrome (FES) and to compare them with eyes of controls. This case-control study included 208 eyes (72 eyes with FES and 136 without FES) of 107 patients (37 patients with FES and 70 without FES). Patients underwent a complete clinical eye examination that included corneal biomechanical evaluation carried out with the Reichert Ocular Response Analyzer. Corneal hysteresis (CH), corneal resistance factor (CRF), central corneal thickness (CCT), Goldmann-correlated intraocular pressure (IOPg), and corneal-compensated intraocular pressure (IOPcc) were evaluated. Mean CH was significantly lower in patients with FES than in those without FES (9.51 ± 1.56 vs. 11.66 ± 9.11; P corneal biomechanical properties could be changed in patients with FES, reflecting additional structural changes in FES.

  3. The Effect of Artificial Tears on Corneal Higher Order Aberrations in Dry Eye Patients

    Directory of Open Access Journals (Sweden)

    Hasan Ali Bayhan

    2014-03-01

    Full Text Available Purpose: To assess the effects of artificial tears on corneal higher order aberrations in dry eye patients. Materials and Methods: 30 right eyes of 30 newly diagnosed dry eye patients were evaluated in this prospective study. After routine ophthalmological examination, Schirmer test and tear break-up time (TBUT test were performed in all patients. Anterior corneal aberrations were derived from conversion of the corneal elevation profile into corneal wavefront data with 6.0 mm pupil diameter using Zernike polynomails by corneal topography before and 5 minutes after instillation of artificial tear (Eyestil®. Corneal optical aberrations were compared before and after instillation of eyedrop. Results: The study included 17 women and 13 men; the average age of the patients was 44.36±13.22 years. Mean TBUT was 4.78±2.78 seconds and mean Schirmer value was 3.58±2.45 mm/5 minutes. After instillation of artificial tear, significant reductions in corneal total aberration from 1.120±0.35 µm to 0.960±0.34 µm, higher order aberration from 0.674±0.26 µm to 0.464±0.18 µm, coma-like aberration from 0.283±0.10 µm to 0.238±0.09 µm, and spherical-like aberration from 0.254±0.11 µm to 0.221±0.08 µm were detected (all, p<0.001. After eyedrop instillation, statistically significant increment was observed in Strehl ratio (p<0.001. Conclusion: As well as reducing the dry eye symptoms, artificial tears also cause increment in optical quality of the eye. Benefits of artificial tears on visual quality can be evaluated objectively via corneal wavefront aberrations. (Turk J Ophthalmol 2014; 44: 119-22

  4. Biomechanics of Corneal Ring Implants

    Science.gov (United States)

    2015-01-01

    Purpose: To evaluate the biomechanics of corneal ring implants by providing a related mathematical theory and biomechanical model for the treatment of myopia and keratoconus. Methods: The spherical dome model considers the inhomogeneity of the tunica of the eye, dimensions of the cornea, lamellar structure of the corneal stroma, and asphericity of the cornea. It is used in this study for calculating a strengthening factor sf for the characterization of different ring-shaped corneal implant designs. The strengthening factor is a measure of the amount of strengthening of the cornea induced by the implant. Results: For ring segments and incomplete rings, sf = 1.0, which indicates that these implants are not able to strengthen the cornea. The intracorneal continuous complete ring (MyoRing) has a strengthening factor of up to sf = 3.2. The MyoRing is, therefore, able to strengthen the cornea significantly. Conclusions: The result of the presented biomechanical analysis of different ring-shaped corneal implant designs can explain the different postoperative clinical results of different implant types in myopia and keratoconus. PMID:26312619

  5. Corneal Protection for Burn Patients

    Science.gov (United States)

    2013-10-01

    report, Figs. 2-7. Rose Bengal (RB) photosensitization was tested because RB is FDA-allowed as a diagnostic for corneal abrasions...incisions. J Cataract Refract Surg, 30, 2420-4. Personnel supported by this grant All personnel are employed by the Massachusetts General Hospital

  6. Biomechanics of Corneal Ring Implants.

    Science.gov (United States)

    Daxer, Albert

    2015-11-01

    To evaluate the biomechanics of corneal ring implants by providing a related mathematical theory and biomechanical model for the treatment of myopia and keratoconus. The spherical dome model considers the inhomogeneity of the tunica of the eye, dimensions of the cornea, lamellar structure of the corneal stroma, and asphericity of the cornea. It is used in this study for calculating a strengthening factor sf for the characterization of different ring-shaped corneal implant designs. The strengthening factor is a measure of the amount of strengthening of the cornea induced by the implant. For ring segments and incomplete rings, sf = 1.0, which indicates that these implants are not able to strengthen the cornea. The intracorneal continuous complete ring (MyoRing) has a strengthening factor of up to sf = 3.2. The MyoRing is, therefore, able to strengthen the cornea significantly. The result of the presented biomechanical analysis of different ring-shaped corneal implant designs can explain the different postoperative clinical results of different implant types in myopia and keratoconus.

  7. Corneale crosslinking voor progressieve keratoconus

    NARCIS (Netherlands)

    Wisse, Robert P L; Soeters, Nienke; Godefrooij, Daniel A.; De Koning-Tahzib, Nayyirih G.

    2016-01-01

    Keratoconus is a corneal disease with onset typically occurring during puberty or early adulthood. The cornea progressively thins and acquires a cone-like shape which negatively affects visual acuity. In the early stages, visual acuity can be corrected with glasses or contact lenses. In more

  8. Corneal biomechanical parameters during pregnancy.

    Science.gov (United States)

    Sen, Emine; Onaran, Yüksel; Nalcacioglu-Yuksekkaya, Pinar; Elgin, Ufuk; Ozturk, Faruk

    2014-01-01

    To evaluate the variation in biomechanical properties and central corneal thickness (CCT) for each trimester during pregnancy and to compare the values with those in nonpregnant women. We prospectively studied the eyes of 32 pregnant and 34 age-matched non-pregnant women. The parameters included corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOP), and corneal-compensated IOP measured by the Ocular Response Analyzer (ORA). The CCT was also measured with an ultrasonic pachymeter attached to the ORA. The mean age was 27.0 ± 3.8 years in the study group and 28.0 ± 4.1 years in the control group. The mean CH measurement was 10.6 ± 1.4 mmHg in the study group and 10.1 ± 1.3 mmHg in the control group. The mean CRF value was 9.6 ± 1.7 mmHg in the study group and 10.0 ± 1.4 mmHg in the control group. The mean CCT value was 541.1 ± 22.4 µm in the study group and 536.5 ± 27.1 µm in the control group. No statistically significant differences were found regarding CH, CRF, or CCT values between the 2 groups (independent t test, p = 0.160, p = 0.355, p = 0.450, respectively). Hormonal changes during pregnancy may not affect corneal biomechanics. This may be due to the balanced effect of the various hormones on the cornea during pregnancy.

  9. Management of corneal bee sting

    Directory of Open Access Journals (Sweden)

    Razmjoo H

    2011-12-01

    Full Text Available Hassan Razmjoo1,2, Mohammad-Ali Abtahi1,2,4, Peyman Roomizadeh1,3, Zahra Mohammadi1,2, Seyed-Hossein Abtahi1,3,41Medical School, Isfahan University of Medical Sciences (IUMS; 2Ophthalmology Ward, Feiz Hospital, IUMS; 3Isfahan Medical Students Research Center (IMSRC, IUMS; 4Isfahan Ophthalmology Research Center (IORC, Feiz Hospital, IUMS, Isfahan, IranAbstract: Corneal bee sting is an uncommon environmental eye injury that can result in various ocular complications with an etiology of penetrating, immunologic, and toxic effects of the stinger and its injected venom. In this study we present our experience in the management of a middle-aged male with a right-sided deep corneal bee sting. On arrival, the patient was complaining of severe pain, blurry vision with acuity of 160/200, and tearing, which he had experienced soon after the injury. Firstly, we administered conventional drugs for eye injuries, including topical antibiotic, corticosteroid, and cycloplegic agents. After 2 days, corneal stromal infiltration and edema developed around the site of the sting, and visual acuity decreased to 100/200. These conditions led us to remove the stinger surgically. Within 25 days of follow-up, the corneal infiltration decreased gradually, and visual acuity improved to 180/200. We suggest a two-stage management approach for cases of corneal sting. For the first stage, if the stinger is readily accessible or primary dramatic reactions, including infiltration, especially on the visual axis, exist, manual or surgical removal would be indicated. Otherwise, we recommend conventional treatments for eye injuries. Given this situation, patients should be closely monitored for detection of any worsening. If the condition does not resolve or even deteriorates, for the second stage, surgical removal of the stinger under local or generalized anesthesia is indicated.Keywords: bee sting, stinger, cornea, removal, management, surgery

  10. [Treatment of corneal ulcers with platelet rich plasma].

    Science.gov (United States)

    Acosta, L; Castro, M; Fernandez, M; Oliveres, E; Gomez-Demmel, E; Tartara, L

    2014-02-01

    To assess the efficacy of platelet rich plasma (PRP) in the treatment of extensive corneal ulcers in albino rabbits. New Zealand rabbits, divided in 3 groups, were used for the study. Corneal ulcers of 10mm diameter were made. Rabbits blood was extracted for the preparation of the PRP of the corresponding group. The blood was processed by differential centrifugation. The first group, named control, was treated with sterile saline every 8h. The second group, named gel, was treated with deproteinized extract gel beef fat every 8h, and the third group, named PRP received one PRP drop on the first and third day of monitoring. The rabbits were monitored, by taking photographs, each day for the 7 days that the study lasted. A better outcome was observed in the group with deproteinized extract gel beef fat (GE group), and the PRP group (PL group), in comparison with the control group (CO group) (P<.05). The PRP showed to be just as effective as the commercial product (Solcoseryl®), for the regeneration of the extensive and deep corneal ulcers. Besides, it stands out as a no surgical procedure is required, and there is easy access, low cost and reduced doses. Copyright © 2013 Sociedad Española de Oftalmología. Published by Elsevier Espana. All rights reserved.

  11. Improvement in corneal scarring following bacterial keratitis.

    Science.gov (United States)

    McClintic, S M; Srinivasan, M; Mascarenhas, J; Greninger, D A; Acharya, N R; Lietman, T M; Keenan, J D

    2013-03-01

    Bacterial keratitis results in corneal scarring and subsequent visual impairment. The long-term evolution of corneal scars has not been well described. In this case series, we identified patients who had improvement in corneal scarring and visual acuity from a clinical trial for bacterial keratitis. We searched the records of the Steroids for Corneal Ulcers Trial (SCUT) for patients who had improvement in vision between the 3-month and 12-month visits and reviewed their clinical photographs. Of the 500 patients enrolled in SCUT, five patients with large central corneal scars due to bacterial keratitis are presented. All experienced improvement in rigid contact lens-corrected visual acuity from months 3 to 12. All patients also had marked improvement in corneal opacity during the same time period. None of the patients opted to have penetrating keratoplasty. Corneal scars may continue to improve even many months after a bacterial corneal ulcer has healed. The corneal remodeling can be accompanied by considerable improvement in visual acuity, such that corneal transplantation may not be necessary.

  12. Imaging, Reconstruction, And Display Of Corneal Topography

    Science.gov (United States)

    Klyce, Stephen D.; Wilson, Steven E.

    1989-12-01

    The cornea is the major refractive element in the eye; even minor surface distortions can produce a significant reduction in visual acuity. Standard clinical methods used to evaluate corneal shape include keratometry, which assumes the cornea is ellipsoidal in shape, and photokeratoscopy, which images a series of concentric light rings on the corneal surface. These methods fail to document many of the corneal distortions that can degrade visual acuity. Algorithms have been developed to reconstruct the three dimensional shape of the cornea from keratoscope images, and to present these data in the clinically useful display of color-coded contour maps of corneal surface power. This approach has been implemented on a new generation video keratoscope system (Computed Anatomy, Inc.) with rapid automatic digitization of the image rings by a rule-based approach. The system has found clinical use in the early diagnosis of corneal shape anomalies such as keratoconus and contact lens-induced corneal warpage, in the evaluation of cataract and corneal transplant procedures, and in the assessment of corneal refractive surgical procedures. Currently, ray tracing techniques are being used to correlate corneal surface topography with potential visual acuity in an effort to more fully understand the tolerances of corneal shape consistent with good vision and to help determine the site of dysfunction in the visually impaired.

  13. Corneal biomechanical properties in thyroid eye disease.

    Science.gov (United States)

    Karabulut, Gamze Ozturk; Kaynak, Pelin; Altan, Cıgdem; Ozturker, Can; Aksoy, Ebru Funda; Demirok, Ahmet; Yılmaz, Omer Faruk

    2014-06-01

    The purpose of this study is to investigate the effect of thyroid eye disease (TED) on the measurement of corneal biomechanical properties and the relationship between these parameters and disease manifestations. A total of 54 eyes of 27 individuals with TED and 52 eyes of 30 healthy control participants were enrolled. Thyroid ophthalmopathy activity was defined using the VISA (vision, inflammation, strabismus, and appearance/exposure) classification for TED. The intraocular pressure (IOP) measurement with Goldmann applanation tonometer (GAT), axial length (AL), keratometry, and central corneal thickness (CCT) measurements were taken from each patient. Corneal biomechanical properties, including corneal hysteresis (CH) and corneal resistance factor (CRF) and noncontact IOP measurements, Goldmann-correlated IOP (IOPg) and corneal-compensated IOP (IOPcc) were measured with the Ocular Response Analyzer (ORA) using the standard technique. Parameters such as best corrected visual acuity, axial length, central corneal thickness, and corneal curvature were not statistically significant between the two groups (p > 0.05). IOP measured with GAT was higher in participants with TED (p corneal resistance factor between groups. However, IOPg and IOPcc were significantly higher in TED patients. CH and VISA grading of TED patients showed a negative correlation (p = 0.007). In conclusion, TED affects the corneal biomechanical properties by decreasing CH. IOP with GAT and IOPg is found to be increased in these patients. As the severity of TED increases, CH decreases in these patients. Copyright © 2014. Published by Elsevier B.V.

  14. Clinical applications of corneal confocal microscopy

    Directory of Open Access Journals (Sweden)

    Mitra Tavakoli

    2008-06-01

    Full Text Available Mitra Tavakoli1, Parwez Hossain2, Rayaz A Malik11Division of Cardiovascular Medicine, University of Manchester and Manchester Royal Infirmary, Manchester, UK; 2University of Southampton, Southampton Eye Unit, Southampton General Hospital, Southampton, UKAbstract: Corneal confocal microscopy is a novel clinical technique for the study of corneal cellular structure. It provides images which are comparable to in-vitro histochemical techniques delineating corneal epithelium, Bowman’s layer, stroma, Descemet’s membrane and the corneal endothelium. Because, corneal confocal microscopy is a non invasive technique for in vivo imaging of the living cornea it has huge clinical potential to investigate numerous corneal diseases. Thus far it has been used in the detection and management of pathologic and infectious conditions, corneal dystrophies and ecstasies, monitoring contact lens induced corneal changes and for pre and post surgical evaluation (PRK, LASIK and LASEK, flap evaluations and Radial Keratotomy, and penetrating keratoplasty. Most recently it has been used as a surrogate for peripheral nerve damage in a variety of peripheral neuropathies and may have potential in acting as a surrogate marker for endothelial abnormalities.Keywords: corneal confocal microscopy, cornea, infective keratitis, corneal dystrophy, neuropathy

  15. Turning the tide of corneal blindness

    Directory of Open Access Journals (Sweden)

    Matthew S Oliva

    2012-01-01

    Full Text Available Corneal diseases represent the second leading cause of blindness in most developing world countries. Worldwide, major investments in public health infrastructure and primary eye care services have built a strong foundation for preventing future corneal blindness. However, there are an estimated 4.9 million bilaterally corneal blind persons worldwide who could potentially have their sight restored through corneal transplantation. Traditionally, barriers to increased corneal transplantation have been daunting, with limited tissue availability and lack of trained corneal surgeons making widespread keratoplasty services cost prohibitive and logistically unfeasible. The ascendancy of cataract surgical rates and more robust eye care infrastructure of several Asian and African countries now provide a solid base from which to dramatically expand corneal transplantation rates. India emerges as a clear global priority as it has the world′s largest corneal blind population and strong infrastructural readiness to rapidly scale its keratoplasty numbers. Technological modernization of the eye bank infrastructure must follow suit. Two key factors are the development of professional eye bank managers and the establishment of Hospital Cornea Recovery Programs. Recent adaptation of these modern eye banking models in India have led to corresponding high growth rates in the procurement of transplantable tissues, improved utilization rates, operating efficiency realization, and increased financial sustainability. The widespread adaptation of lamellar keratoplasty techniques also holds promise to improve corneal transplant success rates. The global ophthalmic community is now poised to scale up widespread access to corneal transplantation to meet the needs of the millions who are currently blind.

  16. Innervation of tissue-engineered recombinant human collagen-based corneal substitutes: a comparative in vivo confocal microscopy study.

    Science.gov (United States)

    Lagali, Neil; Griffith, May; Fagerholm, Per; Merrett, Kimberley; Huynh, Melissa; Munger, Rejean

    2008-09-01

    To compare reinnervation in recombinant human collagen-based corneal substitutes with allografts during a 1-year postimplantation follow-up period in pigs. A retrospective comparison to innervation in porcine collagen-based biosynthetic grafts was also performed. Pigs received a corneal allograft or a substitute made of either recombinant human type-I or -III collagen. In vivo confocal microscopic examination of the central cornea of surgical and untouched control eyes before surgery and at 2, 6, and 12 months after surgery was performed to quantify the number, density, and diameter of nerves at various corneal depths. By 12 months after surgery, the number and density of regenerated nerves in the anterior and deep anterior corneal stroma recovered to preoperative and control levels in both types of substitute grafts and in the allografts. In the subepithelial and subbasal regions, however, significantly fewer nerves were detected relative to those in control subjects at 12 months, regardless of graft type (P collagen-based biosynthetic grafts. An absence of thick stromal nerve trunks (diameter, >10 mum) in all grafts, irrespective of material type, indicated that nerve regeneration in grafts was accompanied by persistent morphologic changes. Nerve regeneration in recombinant human collagen-based biosynthetic corneal grafts proceeded similarly to that in allograft tissue, demonstrating the suitability of recombinant human collagen constructs as nerve-friendly corneal substitutes. Furthermore, only minor differences were noted between type-I and -III collagen grafts, indicating an insensitivity of nerve regeneration to initial collagen type.

  17. Changes of corneal biomechanics with keratoconus.

    Science.gov (United States)

    Wolffsohn, James S; Safeen, Saima; Shah, Sunil; Laiquzzaman, Mohammad

    2012-08-01

    To perform advanced analysis of the corneal deformation response to air pressure in keratoconics compared with age- and sex-matched controls. The ocular response analyzer was used to measure the air pressure-corneal deformation relationship of 37 patients with keratoconus and 37 age (mean 36 ± 10 years)- and sex-matched controls with healthy corneas. Four repeat air pressure-corneal deformation profiles were averaged, and 42 separate parameters relating to each element of the profiles were extracted. Corneal topography and pachymetry were performed with the Orbscan II. The severity of the keratoconus was graded based on a single metric derived from anterior corneal curvatures, difference in astigmatism in each meridian, anterior best-fit sphere, and posterior best-fit sphere. Most of the biomechanical characteristics of keratoconic eyes were significantly different from normal eyes (P corneal applanation. With increasing keratoconus severity, the cornea was thinner (r = -0.407, P corneal concave deformation past applanation was quicker (dive; r2 = -0.314, P = 0.01), and the tear film index was lower (r = -0.319, P = 0.01). The variance in keratoconus severity could be accounted for by the corneal curvature and central corneal thickness (r = 0.80) with biomechanical characteristics contributing an additional 4% (total r = 0.84). The area under the receiver operating characteristic curve was 0.919 ± 0.025 for keratometry alone, 0.965 ± 0.014 with the addition of pachymetry, and 0.972 ± 0.012 combined with ocular response analyzer biomechanical parameters. Characteristics of the air pressure-corneal deformation profile are more affected by keratoconus than the traditionally extracted corneal hysteresis and corneal resistance factors. These biomechanical metrics slightly improved the detection and severity prediction of keratoconus above traditional keratometric and pachymetric assessment of corneal shape.

  18. Evaluation of corneal symmetry after UV corneal crosslinking for keratoconus.

    Science.gov (United States)

    Mofty, Hanan; Alzahrani, Khaled; Carley, Fiona; Harper, Sophie; Brahma, Arun; Au, Leon; Morley, Debbie; Hillarby, M Chantal

    2017-01-01

    The purpose of this study was to assess UV corneal crosslinking (CXL) treatment outcomes for keratoconus by evaluating the corneal regularity in patients through follow-up using the Oculus Pentacam. A total of 18 eyes from CXL patients with keratoconus were studied before and after CXL treatment, and six eyes from six patients who were not treated with CXL served as controls. Treated patients had Pentacam images taken before CXL treatment and regularly 3 months post treatment up to the 12th month. Controls were imaged during their first appointment and after 12 months. Symmetry and asphericity were evaluated and correlated with both best-corrected visual acuity (BCVA) and maximum K -readings. In the CXL-treated group, there was a significant improvement in the index of symmetrical variation (ISV) and keratoconus index (KI) at 3 months and in the index of height asymmetry (IHA) and minimum radius of curvature ( R min ) at 9 months post treatment. On the contrary, the untreated group's indices showed some significant worsening in ISV, KI, central keratoconus index (CKI), and R min . A novel finding in our study was a slight positive shift of anterior asphericity in the 6 mm, 7 mm, and 8 mm 3 months after treatment, which had a correlation with BCVA ( R 2 =0.390, p =0.053) and a strong correlation with maximum K -reading ( R 2 =0.690, p =0.005). However, the untreated group had no significant changes after 1 year. The corneal asymmetrical shape is associated with the spherical aberration alteration influenced by temporal evolution of surface ablation and increased corneal haze. However, insignificant changes in symmetry attest the stabilization effect on cornea postoperatively as compared with controls.

  19. Posterior corneal shape : Comparison of height data from 3 corneal topographers

    NARCIS (Netherlands)

    de Jong, Tim; Sheehan, Matthew T.; Koopmans, Steven A.; Jansonius, Nomdo M.

    Purpose: To compare the ability of 3 clinical corneal topographers to describe the posterior corneal shape. Setting: University Medical Center Groningen, the Netherlands. Design: Prospective observational study. Methods: Corneas of healthy participants were measured twice with a dual Scheimpflug

  20. Value of recombinant human epidermal growth factor in corneal wound repair after corneal foreign body elimination

    OpenAIRE

    Hong-Jie Han

    2013-01-01

    AIM: To investigate the repair efficacy of recombinant human epidermal growth factor on corneal epithelium after corneal foreign body eliminating operation. METHODS: There were 102 patients with corneal foreign body(188 affected eyes)chosen for the study. All patients were divided into treatment group and control group according to the random number table. Both groups received corneal foreign body elimination by slit lamp. Postoperatively, the treatment group was given eye drops containing ep...

  1. Variation of corneal refractive index with hydration

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young L; Walsh, Joseph T Jr.; Goldstick, Thomas K; Glucksberg, Matthew R [Biomedical Engineering Department, Northwestern University, Evanston, IL 60208 (United States)

    2004-03-07

    We report the effect of changes in the corneal hydration on the refractive index of the cornea. Using optical coherence tomography (OCT), the geometrical thickness and the group refractive index of the bovine cornea were derived simultaneously as the corneal hydration was varied. The corneal hydration was then calculated from the corneal thickness. The group refractive index of the cornea increased non-linearly as the cornea dehydrated. In addition, a simple mathematical model was developed, based on the assumption that changes in corneal hydration occur only in the interfibrilar space with constant water content within the collagen fibrils. Good agreement between the experimental results and the mathematical model supports the assumption. The results also demonstrate that the measurement of refractive index is a quantitative indicator of corneal hydration.

  2. Corneal Toxicity Following Exposure to Asclepias Tuberosa

    DEFF Research Database (Denmark)

    Mikkelsen, Lauge Hjorth; Hamoudi, Hassan; Gül, Cigdem Altuntas

    2017-01-01

    PURPOSE: To present a case of corneal toxicity following exposure to milky plant latex from Asclepias tuberosa. METHODS: A 70-year-old female presented with blurred vision and pain in her left eye after handling an Ascepias tuberosa. Clinical examination revealed a corneal stromal oedema with small...... that inhibit the Na+/ K+-ATPase in the corneal endothelium. The oedema resolved after 96 hours. After nine months the best corrected visual acuity was 20/20. CONCLUSION: Corneal toxicity has previously been reported for plants of the Asclepias family. This is a rare case describing severe corneal toxicity...... caused by exposure to latex from Asclepias tuberosa. Handling of plants of the Asclepias family should be kept as a differential diagnosis in cases of acute corneal toxicity....

  3. Genetics Home Reference: lattice corneal dystrophy type I

    Science.gov (United States)

    ... corneal dystrophy type I lattice corneal dystrophy type I Printable PDF Open All Close All Enable Javascript ... expand/collapse boxes. Description Lattice corneal dystrophy type I is an eye disorder that affects the clear, ...

  4. Immunoglobulins in granular corneal dystrophy Groenouw type I

    DEFF Research Database (Denmark)

    Møller, H U; Bojsen-Møller, M; Schrøder, H D

    1993-01-01

    Three patients with granular corneal dystrophy Groenouw type I underwent corneal grafting, and cryostat sections of the corneal buttons were examined immunohistochemically for immunoglobulins. Positive results were obtained for IgG, Kappa-, and Lambda chains with immunofluorescence technique. The...

  5. Corneal epithelium in penetrating keratoplasty.

    Science.gov (United States)

    Meyer, R F; Bobb, K C

    1980-08-01

    We studied corneal epithelium in 66 patients with bullous keratopathy treated with penetrating keratoplasty using McCarey-Kaufman stored donor corneas. Epithelium was evaluated at times of storage, surgery, and postoperative dressing changes. Epithelium was intact in 43 of the donor corneas at storage, and 23 had 5 to 100% (median, 50%) epithelium missing. At the end of the keratoplasty procedure, 16 grafts had epithelium intact, and 50 had 5 to 100% (median, 20%) epithelium missing. Postoperative epithelial healing time ranged from one to 12 days, with a median of two days. Postoperative healing was significantly prolonged when donor corneal epithelium was missing at keratoplasty. As the amount of epithelium intact at the end of surgery decreased, the number of days to heal postoperatively increased. We found that donor corneas could be stored as long as 79 hours, with 63 hours in McCarey-Kaufman medium, and still have epithelium intact at the end of the keratoplasty procedure.

  6. Corneal astigmatism following cataract extraction.

    Science.gov (United States)

    Wishart, M S; Wishart, P K; Gregor, Z J

    1986-01-01

    The changes in corneal curvature in the first six months after cataract extraction were studied by performing sequential keratometry on a group of 57 patients. 8/0 Virgin silk interrupted sutures were used for the closure of corneoscleral incisions, and 10/0 monofilament tied in double running (bootlace) or single running (continuous) fashion was used for corneal wound closure. A high degree of with-the-rule astigmatism was evident in all patients two weeks postoperatively, but thereafter the character of the astigmatism produced by 8/0 virgin silk and 10/0 monofilament closure was quite different: in the 8/0 virgin silk group there was an early and pronounced shift in the axis of astigmatism to against-the-rule, whereas in the 10/0 monofilament group there was little further change in the astigmatism unless the sutures were removed. Wound compression and wound gape as factors responsible for these changes are discussed. PMID:3539177

  7. Glaucoma and Corneal Transplant Procedures

    Directory of Open Access Journals (Sweden)

    Ammar M. Al-Mahmood

    2012-01-01

    Full Text Available Glaucoma after corneal transplantation is a leading cause of ocular morbidity after penetrating keratoplasty. The incidence reported is highly variable and a number of etiologic factors have been identified. A number of treatment options are available; surgical intervention for IOP control is associated with a high incidence of graft failure. IOP elevation is less frequently seen following deep anterior lamellar keratoplasty. Descemet's striping-automated endothelial keratoplasty is also associated with postprocedure intraocular pressure elevation and secondary glaucoma and presents unique surgical challenges in patients with preexisting glaucoma surgeries. Glaucoma exists in up to three-quarters of patients who undergo keratoprosthesis surgery and the management if often challenging. The aim of this paper is to highlight the incidence, etiology, and management of glaucoma following different corneal transplant procedures. It also focuses on the challenges in the diagnosis of glaucoma and intraocular pressure monitoring in this group of patients.

  8. Corneal hemangiosarcoma in a cat.

    Science.gov (United States)

    Cazalot, G; Regnier, A; Deviers, A; Serra, F; Lucas, M N; Etienne, C L; Letron, I Raymond

    2011-09-01

    A 10 year-old castrated male Domestic Short-hair cat with a history of chronic bilateral keratitis was referred for assessment of a red, elevated mass involving the left cornea. The rapid growth of the mass, over a month period in combination with pronounced vascularization and invasion of the corneal surface suggested an aggressive inflammatory or neoplastic process. Following keratectomy, the lesion was diagnosed histopathologically as a hemangiosarcoma. The tumor recurred locally within 3 weeks and enucleation was performed. Histopathologic examination of the globe confirmed the diagnosis and did not reveal infiltration of the limbus and conjunctiva. No signs of local recurrence or metastatic disease have been observed 18 months following enucleation. To the authors' knowledge this is the first case of primary corneal hemangiosarcoma described in the feline species. © 2011 American College of Veterinary Ophthalmologists.

  9. Evaluation of corneal symmetry after UV corneal crosslinking for keratoconus

    Directory of Open Access Journals (Sweden)

    Mofty H

    2017-11-01

    Full Text Available Hanan Mofty,1,2 Khaled Alzahrani,2 Fiona Carley,3 Sophie Harper,3 Arun Brahma,3 Leon Au,3 Debbie Morley,3 M Chantal Hillarby2 1Optometry Department, College of Applied Medical Science, King Saud University, Riyadh, Kingdom of Saudi Arabia; 2Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, 3Manchester Royal Eye Hospital, Manchester, UK Purpose: The purpose of this study was to assess UV corneal crosslinking (CXL treatment outcomes for keratoconus by evaluating the corneal regularity in patients through follow-up using the Oculus Pentacam.Patients and methods: A total of 18 eyes from CXL patients with keratoconus were studied before and after CXL treatment, and six eyes from six patients who were not treated with CXL served as controls. Treated patients had Pentacam images taken before CXL treatment and regularly 3 months post treatment up to the 12th month. Controls were imaged during their first appointment and after 12 months. Symmetry and asphericity were evaluated and correlated with both best-corrected visual acuity (BCVA and maximum K-readings.Results: In the CXL-treated group, there was a significant improvement in the index of symmetrical variation (ISV and keratoconus index (KI at 3 months and in the index of height asymmetry (IHA and minimum radius of curvature (Rmin at 9 months post treatment. On the contrary, the untreated group’s indices showed some significant worsening in ISV, KI, central keratoconus index (CKI, and Rmin. A novel finding in our study was a slight positive shift of anterior asphericity in the 6 mm, 7 mm, and 8 mm 3 months after treatment, which had a correlation with BCVA (R2=0.390, p=0.053 and a strong correlation with maximum K-reading (R2=0.690, p=0.005. However, the untreated group had no significant changes after 1 year.Conclusion: The corneal asymmetrical shape is associated with the spherical aberration alteration

  10. Corneal Donor Tissue Preparation for Endothelial Keratoplasty

    OpenAIRE

    Woodward, Maria A.; Titus, Michael; Mavin, Kyle; Shtein, Roni M.

    2012-01-01

    Over the past ten years, corneal transplantation surgical techniques have undergone revolutionary changes1,2. Since its inception, traditional full thickness corneal transplantation has been the treatment to restore sight in those limited by corneal disease. Some disadvantages to this approach include a high degree of post-operative astigmatism, lack of predictable refractive outcome, and disturbance to the ocular surface. The development of Descemet's stripping endothelial keratoplasty (DSEK...

  11. Corneal Biomechanics Determination in Healthy Myopic Subjects

    OpenAIRE

    Kunliang Qiu; Xuehui Lu; Riping Zhang; Geng Wang; Mingzhi Zhang

    2016-01-01

    Purpose. To determine the corneal biomechanical properties by using the Ocular Response Analyzer? and to investigate potential factors associated with the corneal biomechanics in healthy myopic subjects. Methods. 135 eyes from 135 healthy myopic subjects were included in this cross-sectional observational study. Cornea hysteresis (CH), corneal resistance factor (CRF), cornea-compensated intraocular pressure (IOPcc), and Goldmann-correlated intraocular pressure (IOPg) were determined with the ...

  12. Interaction between Corneal and Internal Ocular Aberrations Induced by Orthokeratology and Its Influential Factors

    Science.gov (United States)

    Chen, Qingzhong; Me, Rao; Yu, Yunjie; Shi, Guangsen

    2017-01-01

    Purpose To investigate the interaction between corneal, internal, and total wavefront aberrations (WAs) and their influential factors during orthokeratology (OK) treatment in Chinese adolescents. Methods Thirty teenagers (n = 30 eyes) were enrolled in the study; spherical equivalent refraction (SE), corneal curvature radius (CCR), central corneal thickness (CCT), WAs, and the difference in limbal transverse diameter and OK lens diameter (ΔLLD) were detected before and after one-month OK treatment. Every component of WAs was measured simultaneously by iTrace aberrometer. The influential factors of OK-induced WAs were analyzed. Results SE and CCT decreased while CCR increased significantly (P < 0.01). Higher-order aberrations (HOAs), Spherical aberrations (SAs), and coma increased significantly (P < 0.01). Corneal horizontal coma (Z31-C) and corneal spherical aberrations (Z40-C) increased (P < 0.01). The HOAs, coma, SAs, Z31-C, Z31-T, Z40-C, and Z40-T were positively correlated with SE and CCR (P < 0.01). Z3−1-C showed negative correlations with (ΔLLD) and positive correlations with SE (P < 0.05). Conclusions The increase in OK-induced HOAs is mainly attributed to Z31 and Z40 of cornea. Z3−1 in the internal component showed a compensative effect on the corneal vertical coma. The degree of myopic correction and increase in CCR may be the essential influential factors of the increase in Z31 and Z40. The appropriate size of the OK lens may be helpful to decrease OK-induced vertical coma. PMID:28845432

  13. Refractive surgery following corneal graft.

    Science.gov (United States)

    Alió, Jorge L; Abdou, Ahmed A; Abdelghany, Ahmed A; Zein, Ghassam

    2015-07-01

    To review the different surgical procedures for management of postkeratoplasty refractive errors after total suture removal. There are different surgical options to address residual refractive errors that frequently occur after corneal transplantation. The correction can be done on the corneal surface or intraocular with intraocular lens (IOL) implantation which requires complete tectonic and refractive stability after suture removal. The most commonly used procedures are photorefractive keratectomy, laser in-situ keratomileusis and Phakic IOLs. Keratoplasty has been profited by recent advances in refractive surgery. Custom excimer laser ablation is an alternative way to treat irregular errors. New IOL modalities are good practical options for a wide range of errors. Femtosecond laser, as a new option in the toolbox, can modify corneal grafting refractive results and assist corrective refractive procedures. Although being the most successful organ transplantation, keratoplasty is usually followed by significant ametropia. Different corrective modalities exist and the choice should fit ocular conditions, patient requirements, surgeon skills and the available technologies. Recent advances in ophthalmic surgery have improved the outcomes.

  14. Refractive surgery after corneal transplantation.

    Science.gov (United States)

    Chang, Daniel H; Hardten, David R

    2005-08-01

    Many patients who have undergone corneal transplantation are unable to achieve satisfactory visual acuity with spectacle and contact lens correction alone. For these patients, refractive surgery becomes a viable option to reduce the post-keratoplasty ametropia. With the many recent advances in refractive surgery for naturally occurring refractive error, new possibilities arise for application to this complicated set of patients. This review discusses key recent developments in refractive surgery after corneal transplantation. The biomechanical effects of incisional keratotomy on post-keratoplasty corneas continue to be studied, and these techniques remain a common and simple method of reducing astigmatism. Photorefractive keratectomy, previously problematic for regression and haze formation, is gaining new prominence as early experience with the adjunctive use of mitomycin C has demonstrated good results. Long-term studies with laser in-situ keratomileusis (LASIK) have continued to show good safety and efficacy. Modern developments in cataract surgery appear to have lower incidences of graft rejection and failure. Developments in lens implantation technology continue to offer expanding options for intraocular refractive surgery. Although visual rehabilitation after corneal transplantation remains a formidable challenge, developments in refractive surgery for naturally occurring ametropias directly translate into an improved ability to help these most challenging refractive cases. Continued research will bring about improved efficacy while maintaining a high level of safety.

  15. Experimental assessment of corneal anisotropy.

    Science.gov (United States)

    Elsheikh, Ahmed; Brown, Michael; Alhasso, Daad; Rama, Paolo; Campanelli, Marino; Garway-Heath, David

    2008-02-01

    To determine the variation of corneal biomechanical properties with anatomical orientation. Strip specimens extracted from fresh porcine corneas were tested under uniaxial tension with strain rates representing static and dynamic loading conditions. The specimens were extracted from the vertical, horizontal, and 45 degrees diagonal directions. The load elongation results were used to derive the stress-strain behavior of each specimen. The average behavior for specimens taken in each anatomical direction was determined along with the effect of strain rate. Specimens from a small number of human corneas were included in the study to verify the findings. Specimens extracted from the vertical direction of porcine and human corneas demonstrated the highest strength (fracture stress) followed by horizontal then diagonal specimens. Vertical specimens were 10% to 20% stronger than horizontal specimens in porcine and human corneas. At low strain rates (1%/min), vertical specimens displayed similar stiffness (resistance to deformation) to horizontal specimens but greater stiffness than diagonal specimens. On increasing the strain rate to 500%/min, the stiffness behavior matched that of strength with vertical specimens being 10% to 20% stiffer than horizontal specimens in porcine and human corneas. The corneal anisotropic behavior is compatible with the preferential orientation of stromal fibrils in the vertical and horizontal directions. Quantifying the effect of this nonuniform fibril organization on corneal anisotropic behavior will be useful in developing numerical models of the cornea for applications where its integrity is compromised such as in simulating refractive surgery procedures.

  16. Obtaining corneal tissue for keratoplasty.

    Science.gov (United States)

    Navarro Martínez-Cantullera, A; Calatayud Pinuaga, M

    2016-10-01

    Cornea transplant is the most common tissue transplant in the world. In Spain, tissue donation activities depend upon transplant coordinator activities and the well-known Spanish model for organ and tissue donation. Tissue donor detection system and tissue donor evaluation is performed mainly by transplant coordinators using the Spanish model on donation. The evaluation of a potential tissue donor from detection until recovery is based on an exhaustive review of the medical and social history, physical examination, family interview to determine will of the deceased, and a laboratory screening test. Corneal acceptance criteria for transplantation have a wider spectrum than other tissues, as donors with active malignancies and infections are accepted for kearatoplasty in most tissue banks. Corneal evaluation during the whole process is performed to ensure the safety of the donor and the recipient, as well as an effective transplant. Last step before processing, corneal recovery, must be performed under standard operating procedures and in a correct environment. Copyright © 2016 Sociedad Española de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.

  17. Central corneal thickness in glaucoma.

    Science.gov (United States)

    Sng, Chelvin C A; Ang, Marcus; Barton, Keith

    2017-03-01

    The purpose of this review is to summarize the role of central corneal thickness (CCT) in the clinical management of a glaucoma patient. The prognostic value of CCT is well recognized in patients with ocular hypertension. However, its predictive value in other glaucoma suspects and patients with established glaucoma is less certain. Tonometry artefacts can result from variations in CCT. However, an adequately validated correction algorithm for Goldmann applanation tonometry measurements does not exist. Newer methods of tonometry are potentially less influenced by CCT but are limited in their clinical use. There may also be biological and genetic associations between corneal thickness and glaucoma. Demographics, environmental factors, glaucoma treatment and the measurement device used have a significant influence on CCT, and should be considered when interpreting the effect of cornea thickness in patients with glaucoma. New measurements of the biomechanical properties of the cornea are likely to be better approximations of the globe biomechanics than CCT, but these require further evaluation. The clinical significance of CCT is well recognized in the context of glaucoma diagnosis and management, though the extent of its importance remains debatable. Corneal biomechanical properties may be more significantly associated with glaucoma than CCT.

  18. Relationship between Corneal Sensation, Blinking, and Tear Film Quality

    National Research Council Canada - National Science Library

    Nosch, Daniela Sonja; Pult, Heiko; Albon, Julie; Purslow, Christine; Murphy, Paul John

    2016-01-01

    PURPOSETo examine the possible role of corneal sensitivity and tear film quality in triggering a blink by investigating the relationship between blink rate, central corneal sensitivity threshold (CST...

  19. Sunsets and Solar Diameter Measurement

    Science.gov (United States)

    Sigismondi, Costantino

    2012-03-01

    A sunset over the sea surface offers the possibility to chronometrate a solar transit across the horizon. The vertical solar diameter is proportional to the duration of the sunset, the cosine of the azimuth and the cosine of the latitude of the observing site. The same formula applies to every circle of equal height, called in arabic almucantarat, and it is exploited in the measurements of the solar diameter made with the Danjon's solar astrolabes. The analogies between sunsets and astrolabes observations are presented, showing advantages and sources of errors of these methods of solar astrometry.

  20. Effects of nicotine on corneal wound healing following acute alkali burn.

    Science.gov (United States)

    Kim, Jong Won; Lim, Chae Woong; Kim, Bumseok

    2017-01-01

    Epidemiological studies have indicated that smoking is a pivotal risk factor for the progression of several chronic diseases. Nicotine, the addictive component of cigarettes, has powerful pathophysiological properties in the body. Although the effects of cigarette smoking on corneal re-epithelialization have been studied, the effects of nicotine on corneal wound healing-related neovascularization and fibrosis have not been fully demonstrated. The aim of this study was to evaluate the effects of chronic administration of nicotine on corneal wound healing following acute insult induced by an alkali burn. BALB/C female mice randomly received either vehicle (2% saccharin) or nicotine (100 or 200 μg/ml in 2% saccharin) in drinking water ad libitum. After 1 week, animals were re-randomized and the experimental group was subjected to a corneal alkali burn, and then nicotine was administered until day 14 after the alkali burn. A corneal alkali burn model was generated by placing a piece of 2 mm-diameter filter paper soaked in 1N NaOH on the right eye. Histopathological analysis and the expression level of the pro-angiogenic genes vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP9) revealed that chronic nicotine administration enhanced alkali burn-induced corneal neovascularization. Furthermore, the mRNA expression of the pro-fibrogenic factors α-smooth muscle actin (αSMA), transforming growth factor-β (TGF-β), and collagen α1 (Col1) was enhanced in the high-concentration nicotine-treated group compared with the vehicle group after corneal injury. Immunohistochemical analysis also showed that the αSMA-positive area was increased in chronic nicotine-treated mice after corneal alkali burn. An in vitro assay found that expression of the α3, α7, and β1 nicotinic acetylcholine receptor (nAChR) subunits was significantly increased by chemical injury in human corneal fibroblast cells. Moreover, alkali-induced fibrogenic gene expression and

  1. Treatment of refractory vernal ulcers with large-diameter bandage contact lenses.

    Science.gov (United States)

    Quah, Say Aun; Hemmerdinger, Chris; Nicholson, Steven; Kaye, Stephen B

    2006-09-01

    To report two cases of refractory vernal ulcers in which the fitting of a large-diameter (22 mm) hydrogel (Contaflex T75) bandage contact lens (BCL) ameliorated the signs and symptoms of the condition. Two patients with refractory vernal ulcers are described. Mechanisms of the effect of a large-diameter lens across the ocular surface are discussed in this condition. The first patient is a 10-year-old boy who had been treated unsuccessfully for a left vernal corneal ulcer with topical prednisolone 0.5% and olopatadine. The vernal ulcer resolved 2 weeks after the fitting of a large-diameter BCL. The second patient is a 4-year-old boy who had been intolerant of all his previous topical medications partly because of his ocular discomfort in association with the right vernal ulcer. A large-diameter BCL was fitted in his right eye. The BCL was removed 2 weeks later with complete healing of the corneal vernal ulcer. Owing to his improved comfort, the patient was able to tolerate topical prednisolone 0.5% drops. Large-diameter BCLs may be a useful treatment option in the management of refractory vernal ulcers.

  2. Diameter Measurement in Bald Cypress

    Science.gov (United States)

    Bernard R. Parresol; James E. Hotvedt

    1990-01-01

    The usual practice of measuring diameter at 4.5 feet ( 1.3 m) or Dbh is meaningless in wetland tree species such as bald cypress (Taxodium distichum (L.) Rich.), due to the presence of fluted basal swells. Since buttress dimensions usually have no consistent relation to volume or form in the tree, the current practice among...

  3. Response of corneal hysteresis and central corneal thickness following clear corneal cataract surgery.

    Science.gov (United States)

    Kandarakis, Artemios; Soumplis, Vasileios; Karampelas, Michalis; Koutroumanos, Ioannis; Panos, Christos; Kandarakis, Stylianos; Karagiannis, Dimitrios

    2012-09-01

    To evaluate the effect of routine phacoemulsification in corneal viscoelastic properties determined by corneal hysteresis (CH) and central corneal thickness (CCT) and to explore the impact of phaco energy on the above parameters. Forty-one eyes of 41 patients undergoing cataract surgery were enrolled in this prospective study. CH and CCT were measured preoperatively, 1 day and 1 week postoperatively. CCT measurement was performed using a non-contact optical pachymeter followed by ocular response analyzer (ORA) examination. Intraoperatively ultrasound time, average phaco power and effective phaco time (EPT) were recorded. Mean CH was 10.05±1.86 mmHg preoperatively, 8.25±1.85 mmHg 1 day and 9.12±1.37 mmHg 1 week postoperatively (pcorneal alterations following cataract surgery resulted in a statistical change in CH and CCT. These two parameters responded in a different manner that clearly demarcates their different nature. On the first postoperative day, CCT increase was correlated at a statistically significant level with intraoperative EPT. This correlation was not found with CH reduction. Other factors, besides cornea oedema or phacoemulsification energy, could be responsible for this CH modification. © 2011 The Authors. Acta Ophthalmologica © 2011 Acta Ophthalmologica Scandinavica Foundation.

  4. Altered corneal stromal matrix organization is associated with mucopolysaccharidosis I, III and VI.

    Science.gov (United States)

    Alroy, J; Haskins, M; Birk, D E

    1999-05-01

    The presence of cloudy corneas is a prominent feature of mucopolysaccharidosis (MPS) types I and VI, but not MPS IIIA or IIIB. The cause of corneal cloudiness in MPS I and VI is speculative. Transparency of the cornea is dependent on the uniform diameter and the regular spacing and arrangement of the collagen fibrils within the stroma. Alterations in the spacing of collagen fibrils in a variety of conditions including corneal edema, scars, and macular corneal dystrophy is clinically manifested as corneal opacity. The purpose of this study was to compare the structural organization of the stromal extracellular matrix of normal corneas with that of MPS corneas. The size and arrangement of collagen fibrils in cloudy corneas from patients with MPS I were examined. The alterations observed were an increased mean fibril diameter with a broader distribution in the MPS corneas. The MPS I corneas also had altered fibril spacing and more irregular packing compared with normal control corneas. The clear corneas of patients with MPS IIIA and IIIB also showed increases in mean fibril diameter and fibril spacing. However, there was less variation indicating more regularity than seen in MPS I. In addition, corneas from cat models of certain MPS were compared to the human corneas. Cats with MPS I and VI, as well as normal control cats, were examined. Structural alterations comparable to those seen in human MPS corneas were seen in MPS I and VI cats relative to normal clear corneas. The findings suggest that cloudy corneas in MPS I and VI are in part a consequence of structural alterations in the corneal stroma, including abnormal spacing, size, and arrangement of collagen fibrils. Copyright 1999 Academic Press.

  5. Corneal donor tissue preparation for endothelial keratoplasty.

    Science.gov (United States)

    Woodward, Maria A; Titus, Michael; Mavin, Kyle; Shtein, Roni M

    2012-06-12

    Over the past ten years, corneal transplantation surgical techniques have undergone revolutionary changes. Since its inception, traditional full thickness corneal transplantation has been the treatment to restore sight in those limited by corneal disease. Some disadvantages to this approach include a high degree of post-operative astigmatism, lack of predictable refractive outcome, and disturbance to the ocular surface. The development of Descemet's stripping endothelial keratoplasty (DSEK), transplanting only the posterior corneal stroma, Descemet's membrane, and endothelium, has dramatically changed treatment of corneal endothelial disease. DSEK is performed through a smaller incision; this technique avoids 'open sky' surgery with its risk of hemorrhage or expulsion, decreases the incidence of postoperative wound dehiscence, reduces unpredictable refractive outcomes, and may decrease the rate of transplant rejection. Initially, cornea donor posterior lamellar dissection for DSEK was performed manually resulting in variable graft thickness and damage to the delicate corneal endothelial tissue during tissue processing. Automated lamellar dissection (Descemet's stripping automated endothelial keratoplasty, DSAEK) was developed to address these issues. Automated dissection utilizes the same technology as LASIK corneal flap creation with a mechanical microkeratome blade that helps to create uniform and thin tissue grafts for DSAEK surgery with minimal corneal endothelial cell loss in tissue processing. Eye banks have been providing full thickness corneas for surgical transplantation for many years. In 2006, eye banks began to develop methodologies for supplying precut corneal tissue for endothelial keratoplasty. With the input of corneal surgeons, eye banks have developed thorough protocols to safely and effectively prepare posterior lamellar tissue for DSAEK surgery. This can be performed preoperatively at the eye bank. Research shows no significant difference in

  6. Role of Decorin Core Protein in Collagen Organisation in Congenital Stromal Corneal Dystrophy (CSCD)

    Science.gov (United States)

    Kamma-Lorger, Christina S.; Pinali, Christian; Martínez, Juan Carlos; Harris, Jon; Young, Robert D.; Bredrup, Cecilie; Crosas, Eva; Malfois, Marc; Rødahl, Eyvind

    2016-01-01

    The role of Decorin in organising the extracellular matrix was examined in normal human corneas and in corneas from patients with Congenital Stromal Corneal Dystrophy (CSCD). In CSCD, corneal clouding occurs due to a truncating mutation (c.967delT) in the decorin (DCN) gene. Normal human Decorin protein and the truncated one were reconstructed in silico using homology modelling techniques to explore structural changes in the diseased protein. Corneal CSCD specimens were also examined using 3-D electron tomography and Small Angle X-ray diffraction (SAXS), to image the collagen-proteoglycan arrangement and to quantify fibrillar diameters, respectively. Homology modelling showed that truncated Decorin had a different spatial geometry to the normal one, with the truncation removing a major part of the site that interacts with collagen, compromising its ability to bind effectively. Electron tomography showed regions of abnormal stroma, where collagen fibrils came together to form thicker fibrillar structures, showing that Decorin plays a key role in the maintenance of the order in the normal corneal extracellular matrix. Average diameter of individual fibrils throughout the thickness of the cornea however remained normal. PMID:26828927

  7. Role of Decorin Core Protein in Collagen Organisation in Congenital Stromal Corneal Dystrophy (CSCD.

    Directory of Open Access Journals (Sweden)

    Christina S Kamma-Lorger

    Full Text Available The role of Decorin in organising the extracellular matrix was examined in normal human corneas and in corneas from patients with Congenital Stromal Corneal Dystrophy (CSCD. In CSCD, corneal clouding occurs due to a truncating mutation (c.967delT in the decorin (DCN gene. Normal human Decorin protein and the truncated one were reconstructed in silico using homology modelling techniques to explore structural changes in the diseased protein. Corneal CSCD specimens were also examined using 3-D electron tomography and Small Angle X-ray diffraction (SAXS, to image the collagen-proteoglycan arrangement and to quantify fibrillar diameters, respectively. Homology modelling showed that truncated Decorin had a different spatial geometry to the normal one, with the truncation removing a major part of the site that interacts with collagen, compromising its ability to bind effectively. Electron tomography showed regions of abnormal stroma, where collagen fibrils came together to form thicker fibrillar structures, showing that Decorin plays a key role in the maintenance of the order in the normal corneal extracellular matrix. Average diameter of individual fibrils throughout the thickness of the cornea however remained normal.

  8. Ultrastructure Organization of Collagen Fibrils and Proteoglycans of Stingray and Shark Corneal Stroma

    Directory of Open Access Journals (Sweden)

    Saud A. Alanazi

    2015-01-01

    Full Text Available We report here the ultrastructural organization of collagen fibrils (CF and proteoglycans (PGs of the corneal stroma of both the stingray and the shark. Three corneas from three stingrays and three corneas from three sharks were processed for electron microscopy. Tissues were embedded in TAAB 031 resin. The corneal stroma of both the stingray and shark consisted of parallel running lamellae of CFs which were decorated with PGs. In the stingray, the mean area of PGs in the posterior stroma was significantly larger than the PGs of the anterior and middle stroma, whereas, in the shark, the mean area of PGs was similar throughout the stroma. The mean area of PGs of the stingray was significantly larger compared to the PGs, mean area of the shark corneal stroma. The CF diameter of the stingray was significantly smaller compared to the CF diameter in the shark. The ultrastructural features of the corneal stroma of both the stingray and the shark were similar to each other except for the CFs and PGs. The PGs in the stingray and shark might be composed of chondroitin sulfate (CS/dermatan sulfate (DS PGs and these PGs with sutures might contribute to the nonswelling properties of the cornea of the stingray and shark.

  9. Optic disc planimetry, corneal hysteresis, central corneal thickness, and intraocular pressure as risk factors for glaucoma.

    Science.gov (United States)

    Carbonaro, Francis; Hysi, Pirro G; Fahy, Samantha J; Nag, Abhishek; Hammond, Christopher J

    2014-02-01

    To determine whether corneal hysteresis and central corneal thickness are independent risk factors for glaucoma. A cross-sectional population-based cohort study. Associations were tested between corneal hysteresis, measured in 1754 population-based subjects from the TwinsUK cohort, and glaucoma-related endophenotypes, including intraocular pressure (IOP), vertical cup-to-disc ratio, optic disc area, and optic disc cup area. Corneal hysteresis, IOP, and central corneal thickness (CCT) were measured; optic disc photographs were analyzed; and multivariable linear regression analysis was performed. Data were available on 1645 individuals. Multiple regression analysis showed corneal hysteresis to be significantly negatively associated with age (beta coefficient = -0.03, P Corneal hysteresis was also found to be associated with CCT (beta coefficient = 0.02, P corneal hysteresis and optic disc area (P = .6), cup area (P = .77), vertical cup-to-disc ratio (P = .51), or spherical equivalent (P = .08). CCT was also found to be significantly associated with IOP (beta coefficient = 3.3, P corneal hysteresis (beta coefficient = 9.4, P corneal hysteresis or CCT and quantitative measures of optic disc cupping, suggesting that corneal hysteresis and CCT are not independent risk factors for glaucoma. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Delayed corneal epithelial wound healing after penetrating keratoplasty in individuals with lattice corneal dystrophy.

    Science.gov (United States)

    Kawamoto, Koji; Morishige, Naoyuki; Yamada, Naoyuki; Chikama, Tai-Ichiro; Nishida, Teruo

    2006-07-01

    To investigate whether corneal epithelial cells of individuals with lattice corneal dystrophy (LCD) possess an intrinsic defect. Retrospective case-control study. The medical charts of nine individuals with LCD and those of 14 patients with keratoconus and 11 patients with corneal leukoma (controls), all of whom underwent penetrating keratoplasty (PKP) in one eye at Yamaguchi University Hospital between February 1998 and November 2001, were examined for the time for epithelial resurfacing after surgery. The time required for resurfacing of the corneal epithelium after PKP was significantly greater in LCD patients (8.56 +/- 4.95 days, mean +/- SD) than in patients with either keratoconus (1.71 +/- 0.91 days, P = .006) or corneal leukoma (3.00 +/- 1.95 days, P = .03). Corneal epithelial wound healing was delayed in LCD patients after PKP, suggesting that the keratoepithelin gene mutations responsible for this condition affect corneal epithelial cells.

  11. Association between corneal hysteresis and central corneal thickness in glaucomatous and non-glaucomatous eyes.

    Science.gov (United States)

    Mangouritsas, George; Morphis, George; Mourtzoukos, Spyridon; Feretis, Elias

    2009-11-01

    We aimed to determine corneal hysteresis values (CH) using the ocular response analyser (ORA) in non-glaucomatous and glaucomatous eyes and their relationship with central corneal thickness (CCT). Corneal hysteresis, intraocular pressure (IOP) as measured by Goldmann applanation tonometry (GAT) and CCT were prospectively evaluated in 74 non-glaucoma subjects with IOP Corneal hysteresis was significantly lower in eyes with treated POAG than in non-glaucomatous eyes. The corneal biomechanical response was strongly associated with CCT in non-glaucoma subjects, but only moderately so in glaucoma patients. It can be assumed that diverse structural factors, in addition to thickness, determine the differences in the corneal biomechanical profile between non-glaucomatous and glaucomatous eyes. Corneal hysteresis could be a useful tool in the diagnosis of glaucoma.

  12. Finite element modeling of corneal strip extensometry

    CSIR Research Space (South Africa)

    Botha, N

    2012-12-01

    Full Text Available symmetric conicoid [19]: (x xo) 2+(y yo) 2+(1+Q)(z zo) 2 2R(z zo) 2 = 0; (2) c SACAM 2012 25 Top view Isometric view Initial corneal curvature z y x x y z Fig. 3: Finite element model of the vertical corneal strip, including the orthogonal...

  13. Corneal staining after treatment with topical tetracycline

    NARCIS (Netherlands)

    Lapid-Gortzak, Ruth; Nieuwendaal, Carla P.; Slomovic, Allan R.; Spanjaard, Lodewijk

    2006-01-01

    PURPOSE: The purpose of this paper is to report a case of corneal staining after treatment with topical tetracycline. METHODS: A patient with crystalline keratopathy caused by Streptococcus viridans after corneal transplantation was treated topically with tetracycline eye drops, based on results of

  14. Corynebacterium macginleyi isolated from a corneal ulcer

    Directory of Open Access Journals (Sweden)

    Kathryn Ruoff

    2010-02-01

    Full Text Available We report the isolation of Corynebacterium macginleyi from the corneal ulcer culture of a patient, later enrolled in the Steroids for Corneal Ulcer Trial (SCUT. To our knowledge this is the first published report from North America of the recovery of C. macginleyi from a serious ocular infection.

  15. Corneal hysteresis and its relevance to glaucoma

    Science.gov (United States)

    Deol, Madhvi; Taylor, David A.; Radcliffe, Nathan M.

    2015-01-01

    Purpose of review Glaucoma is a leading cause of irreversible blindness worldwide. It is estimated that roughly 60.5 million people had glaucoma in 2010 and that this number is increasing. Many patients continue to lose vision despite apparent disease control according to traditional risk factors. The purpose of this review is to discuss the recent findings with regard to corneal hysteresis, a variable that is thought to be associated with the risk and progression of glaucoma. Recent findings Low corneal hysteresis is associated with optic nerve and visual field damage in glaucoma and the risk of structural and functional glaucoma progression. In addition, hysteresis may enhance intraocular pressure (IOP) interpretation: low corneal hysteresis is associated with a larger magnitude of IOP reduction following various glaucoma therapies. Corneal hysteresis is dynamic and may increase in eyes after IOP-lowering interventions are implemented. Summary It is widely accepted that central corneal thickness is a predictive factor for the risk of glaucoma progression. Recent evidence shows that corneal hysteresis also provides valuable information for several aspects of glaucoma management. In fact, corneal hysteresis may be more strongly associated with glaucoma presence, risk of progression, and effectiveness of glaucoma treatments than central corneal thickness. PMID:25611166

  16. Corneal Biomechanics Determination in Healthy Myopic Subjects

    Science.gov (United States)

    Qiu, Kunliang; Lu, Xuehui; Zhang, Riping; Wang, Geng

    2016-01-01

    Purpose. To determine the corneal biomechanical properties by using the Ocular Response Analyzer™ and to investigate potential factors associated with the corneal biomechanics in healthy myopic subjects. Methods. 135 eyes from 135 healthy myopic subjects were included in this cross-sectional observational study. Cornea hysteresis (CH), corneal resistance factor (CRF), cornea-compensated intraocular pressure (IOPcc), and Goldmann-correlated intraocular pressure (IOPg) were determined with the Reichert Ocular Response Analyzer (ORA). Univariate and multivariate regression analyses were performed to investigate factors associated with corneal biomechanics. Results. The mean CH and CRF were 9.82 ± 1.34 mmHg and 9.64 ± 1.57 mmHg, respectively. In univariate regression analysis, CH was significantly correlated with axial length, refraction, central corneal thickness (CCT), and IOPg (r = −0.27, 0.23, 0.45, and 0.21, resp.; all with p ≤ 0.015), but not with corneal curvature or age; CRF was significantly correlated with CCT and IOPg (r = 0.52 and 0.70, resp.; all with p corneal curvature, or age. In multivariate regression analysis, axial length, IOPcc, and CCT were found to be independently associated with CH, while CCT and IOPg were associated with CRF. Conclusions. Both CH and CRF were positively correlated with CCT. Lower CH but not CRF was associated with increasing degree of myopia. Evaluation of corneal biomechanical properties should take CCT and myopic status into consideration. PMID:27525109

  17. Corneal hysteresis and its relevance to glaucoma.

    Science.gov (United States)

    Deol, Madhvi; Taylor, David A; Radcliffe, Nathan M

    2015-03-01

    Glaucoma is a leading cause of irreversible blindness worldwide. It is estimated that roughly 60.5 million people had glaucoma in 2010 and that this number is increasing. Many patients continue to lose vision despite apparent disease control according to traditional risk factors. The purpose of this review is to discuss the recent findings with regard to corneal hysteresis, a variable that is thought to be associated with the risk and progression of glaucoma. Low corneal hysteresis is associated with optic nerve and visual field damage in glaucoma and the risk of structural and functional glaucoma progression. In addition, hysteresis may enhance intraocular pressure (IOP) interpretation: low corneal hysteresis is associated with a larger magnitude of IOP reduction following various glaucoma therapies. Corneal hysteresis is dynamic and may increase in eyes after IOP-lowering interventions are implemented. It is widely accepted that central corneal thickness is a predictive factor for the risk of glaucoma progression. Recent evidence shows that corneal hysteresis also provides valuable information for several aspects of glaucoma management. In fact, corneal hysteresis may be more strongly associated with glaucoma presence, risk of progression, and effectiveness of glaucoma treatments than central corneal thickness.

  18. Inhibition of Corneal Neovascularization by Hydrazinocurcumin ...

    African Journals Online (AJOL)

    Purpose: To investigate the effect of hydrazinocurcumin on a human vascular endothelial growth factor (VEGF)-induced corneal neovascularization in rabbit model. Methods: Murine corneal neovascularization (CorNV) was induced via two intrastromal implantations of VEGF polymer 2 mm from the limbus.

  19. Corneal plaque containing levofloxacin in a dog.

    Science.gov (United States)

    Park, Young-Woo; Kang, Byung-Jae; Lim, Jae Hyun; Ahn, Jung-Mo; Lim, Hyun Sook

    2015-11-01

    A 13-year-old castrated male Yorkshire terrier developed a corneal ulcer 2 weeks after intracapsular lens extraction (ICLE) in the right eye. The corneal ulcer was treated with levofloxacin eye drops. A plaque with a white luster developed in the central cornea 2 weeks after treatment with levofloxacin eye drops. The corneal plaque was surgically removed under inhalant anesthesia. The corneal plaque displayed antimicrobial activity against Escherichia coli. Furthermore, levofloxacin content in the plaque was confirmed by matrix-assisted laser desorption/ionization time-of-flight/time-of-flight (MALDI-TOF/TOF) mass spectrometry (MS). The corneal ulcer completely resolved 2 weeks after the surgical removal of the corneal lesion and replacement of levofloxacin eye drops with tobramycin eye drops. Although the topical use of levofloxacin is unlikely to lead to corneal chemical deposits due to the high water solubility of the drug compared to other topical fluoroquinolones, this patient developed corneal plaque of the antibiotic drop. © 2015 American College of Veterinary Ophthalmologists.

  20. Corneal laceration caused by river crab

    Directory of Open Access Journals (Sweden)

    Vinuthinee N

    2015-01-01

    Full Text Available Naidu Vinuthinee,1,2 Anuar Azreen-Redzal,1 Jaafar Juanarita,1 Embong Zunaina2 1Department of Ophthalmology, Hospital Sultanah Bahiyah, Alor Setar, 2Department of Ophthalmology, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Malaysia Abstract: A 5-year-old boy presented with right eye pain associated with tearing and photophobia of 1-day duration. He gave a history of playing with a river crab when suddenly the crab clamped his fingers. He attempted to fling the crab off, but the crab flew and hit his right eye. Ocular examination revealed a right eye corneal ulcer with clumps of fibrin located beneath the corneal ulcer and 1.6 mm level of hypopyon. At presentation, the Seidel test was negative, with a deep anterior chamber. Culture from the corneal scrapping specimen grew Citrobacter diversus and Proteus vulgaris, and the boy was treated with topical gentamicin and ceftazidime eyedrops. Fibrin clumps beneath the corneal ulcer subsequently dislodged, and revealed a full-thickness corneal laceration wound with a positive Seidel test and shallow anterior chamber. The patient underwent emergency corneal toileting and suturing. Postoperatively, he was treated with oral ciprofloxacin 250 mg 12-hourly for 1 week, topical gentamicin, ceftazidime, and dexamethasone eyedrops for 4 weeks. Right eye vision improved to 6/9 and 6/6 with pinhole at the 2-week follow-up following corneal suture removal. Keywords: corneal ulcer, pediatric trauma, ocular injury

  1. Complications from Infective Corneal Conditions Treated by ...

    African Journals Online (AJOL)

    Background: Complications from infective corneal conditions are an important cause of blindness in adults and children. The eyelids play a major role in the pathogenesis of staphyloma and the perforation of descemetoceles. Tarsorrhaphy could, therefore, be beneficial in treating serious complications from infective corneal ...

  2. Facts about the Cornea and Corneal Disease

    Science.gov (United States)

    ... the Cornea and Corneal Disease Facts About the Cornea and Corneal Disease What is the cornea? The cornea is the eye’s outermost layer. It ... your vision. What are the parts of the cornea? Although the cornea may look clear and seem ...

  3. Corneal ulcers: For the general practitioner

    African Journals Online (AJOL)

    153 CME April 2013 Vol. 31 No. 4. Corneal ulcers: For the general practitioner. A corneal ulcer is a defect in the epithelial layer of the cornea. e general practitioner may play an important role in early management and appropriate referral. Incidence varies and depends on aetiology. S Ballim, MB ChB, Dip Ophth (SA), FC ...

  4. Inhibition of Corneal Neovascularization by Hydrazinocurcumin

    African Journals Online (AJOL)

    Purpose: To investigate the effect of hydrazinocurcumin on a human vascular endothelial growth factor. (VEGF)-induced corneal neovascularization in rabbit model. Methods: Murine corneal neovascularization (CorNV) was induced via two intrastromal implantations of. VEGF polymer 2 mm from the limbus.

  5. Molecular expression in transfected corneal endothelial cells

    Science.gov (United States)

    Wang, Fan; Miao, Zhuang; Lu, Chengwei; Hao, Jilong

    2017-10-01

    To investigate the capability of human corneal endothelial cells serving as immunological cells. Expression of HLA-DP, -DQ, -DR, CD40, CD80, and CD86 was determined by immunohistochemical methods. Meanwhile, purified peripheral blood mononuclear cells were cocultured with human corneal endothelial cells which were pre-treated with and without -IFN respectively, activation of lymphocytes was determined by FACS analysis. In coculture system, T lymphocyte was activated by corneal endothelial cells, HLA-DP, -DQ, -DR and CD40 expression were increased by - IFN induction. Costimulatory molecular CD80 was shown on the endothelial cells. Human corneal endothelial cells were assumed to be involved in the corneal transplantation rejection process as potential antigen presenting cells.

  6. High voltage variable diameter insulator

    Science.gov (United States)

    Vanecek, David L.; Pike, Chester D.

    1984-01-01

    A high voltage feedthrough assembly (10) having a tubular insulator (15) extending between the ground plane ring (16) and the high voltage ring (30). The insulator (15) is made of Pyrex and decreases in diameter from the ground plane ring (16) to the high voltage ring (30), producing equipotential lines almost perpendicular to the wall (27) of the insulator (15) to optimize the voltage-holding capability of the feedthrough assembly (10).

  7. Corneal biomechanical properties in thyroid eye disease

    Directory of Open Access Journals (Sweden)

    Gamze Ozturk Karabulut

    2014-06-01

    Full Text Available The purpose of this study is to investigate the effect of thyroid eye disease (TED on the measurement of corneal biomechanical properties and the relationship between these parameters and disease manifestations. A total of 54 eyes of 27 individuals with TED and 52 eyes of 30 healthy control participants were enrolled. Thyroid ophthalmopathy activity was defined using the VISA (vision, inflammation, strabismus, and appearance/exposure classification for TED. The intraocular pressure (IOP measurement with Goldmann applanation tonometer (GAT, axial length (AL, keratometry, and central corneal thickness (CCT measurements were taken from each patient. Corneal biomechanical properties, including corneal hysteresis (CH and corneal resistance factor (CRF and noncontact IOP measurements, Goldmann-correlated IOP (IOPg and corneal-compensated IOP (IOPcc were measured with the Ocular Response Analyzer (ORA using the standard technique. Parameters such as best corrected visual acuity, axial length, central corneal thickness, and corneal curvature were not statistically significant between the two groups (p > 0.05. IOP measured with GAT was higher in participants with TED (p < 0.001. The CH of TED patients was significantly lower than that of the control group. There was no significant difference in the corneal resistance factor between groups. However, IOPg and IOPcc were significantly higher in TED patients. CH and VISA grading of TED patients showed a negative correlation (p = 0.007. In conclusion, TED affects the corneal biomechanical properties by decreasing CH. IOP with GAT and IOPg is found to be increased in these patients. As the severity of TED increases, CH decreases in these patients.

  8. Corneal manifestations of ocular demodex infestation.

    Science.gov (United States)

    Kheirkhah, Ahmad; Casas, Victoria; Li, Wei; Raju, Vadrevu K; Tseng, Scheffer C G

    2007-05-01

    To report the corneal manifestations in eyes with Demodex infestation of the eyelids. Noncomparative, interventional case series. This retrospective review included six patients with Demodex blepharitis who also exhibited corneal abnormalities, which led to suspicion of limbal stem cell deficiency in three cases. All patients received weekly lid scrubs with 50% tea tree oil and a daily lid scrubs with tea tree shampoo for a minimum of six weeks. Improvement of symptoms and corneal and conjunctival signs were evaluated. All six patients exhibited ocular irritation and conjunctival inflammation, while meibomian gland dysfunction (n = 5), rosacea (n = 4), and decreased vision (n = 3) also were noted despite prior treatments with oral tetracycline, topical steroids with antibiotics, and lid scrub with baby shampoo. These patients were proven to have Demodex folliculorum (n = 6) and Demodex brevis (n = 3) by microscopic examination of epilated lashes. Their corneal manifestation included superficial corneal vascularization (six eyes of five cases), marginal corneal infiltration (two eyes of two cases), phlyctenule-like lesion (one eye of one case), superficial corneal opacity (two eyes of two cases), and nodular corneal scar (two eyes of two cases). After treatment, the Demodex count was reduced from 6.8 +/- 2.8 to 1 +/- 0.9 (standard deviation; P = .001). All patients showed dramatic resolution of ocular irritation, conjunctival inflammation, and all inflammatory, but not scarred, corneal signs; three patients showed improved vision. A variety of corneal pathologic features together with conjunctival inflammation, commonly noted in rosacea, can be found in patients with Demodex infestation of the eyelids. When conventional treatments for rosacea fail, one may consider lid scrub with tea tree oil to eradicate mites as a new treatment.

  9. Collagen Cross-Linking Using Riboflavin and Ultraviolet-A for Corneal Thinning Disorders

    Science.gov (United States)

    Pron, G; Ieraci, L; Kaulback, K

    2011-01-01

    with any generic form of riboflavin, is licensed by Health Canada for the indication to slow or stop the progression of corneal thinning caused by progressive keratectasia, iatrogenic keratectasia after laser-assisted in situ keratomileusis (LASIK) and pellucid marginal degeneration. The same device is named the UV-X® device by IROCMedical, with approvals in Argentina, the European Union and Australia. UVA devices all use light emitting diodes to generate UVA at a wavelength of 360-380 microns but vary in the number of diodes (5 to 25), focusing systems, working distance, beam diameter, beam uniformity and extent to which the operator can vary the parameters. In Ontario, CXL is currently offered at over 15 private eye clinics by refractive surgeons and ophthalmologists. The treatment is an outpatient procedure generally performed with topical anesthesia. The treatment consists of several well defined procedures. The epithelial cell layer is first removed, often using a blunt spatula in a 9.0 mm diameter under sterile conditions. This step is followed by the application of topical 0.1% riboflavin (vitamin B2) solution every 3 to 5 minutes for 25 minutes to ensure that the corneal stroma is fully penetrated. A solid-state UVA light source with a wavelength of 370 nm (maximum absorption of riboflavin) and an irradiance of 3 mW/cm2 is used to irradiate the central cornea. Following treatment, a soft bandage lens is applied and prescriptions are given for oral pain medications, preservative-free tears, anti-inflammatory drops (preferably not nonsteroidal anti-inflammatory drugs, or NSAIDs) and antibiotic eye drops. Patients are recalled 1 week following the procedure to evaluate re-epithelialization and they are followed-up subsequently. Evidence-Based Analysis Methods A literature search was conducted on photochemical corneal collagen cross-linking with riboflavin (vitamin B2) and ultraviolet-A for the management of corneal thinning disorders using a search strategy with

  10. Dynamic OCT measurement of corneal deformation by an air puff in normal and cross-linked corneas

    Science.gov (United States)

    Dorronsoro, Carlos; Pascual, Daniel; Pérez-Merino, Pablo; Kling, Sabine; Marcos, Susana

    2012-01-01

    A new technique is presented for the non-invasive imaging of the dynamic response of the cornea to an air puff inducing a deformation. A spectral OCT instrument combined with an air tonometer in a non-collinear configuration was used to image the corneal deformation over full corneal cross-sections, as well as to obtain high speed measurements of the temporal evolution of the corneal apex. The entire deformation process can be dynamically visualized. A quantitative analysis allows direct extraction of several deformation parameters, such as amplitude, diameter and volume of the maximum deformation, as well as duration and speed of the increasing deformation period and the recovery period. The potential of the technique is demonstrated on porcine corneas in vitro under constant IOP for several conditions (untreated, after riboflavin instillation and under cross-linking with ultraviolet light), as well as on human corneas in vivo. The new technique has proved very sensitive to detect differences in the deformation parameters across conditions. We have confirmed non-invasively that Riboflavin and UV-cross-linking induce changes in the corneal biomechanical properties. Those differences appear to be the result of changes in constituent properties of the cornea, and not a consequence of changes in corneal thickness, geometry or IOP. These measurements are a first step for the estimation of the biomechanical properties of corneal tissue, at an individual level and in vivo, to improve diagnosis and prognosis of diseases and treatments involving changes in the biomechanical properties of the cornea. PMID:22435096

  11. Collagen type I and type V are present in the same fibril in the avian corneal stroma.

    Science.gov (United States)

    Birk, D E; Fitch, J M; Babiarz, J P; Linsenmayer, T F

    1988-03-01

    The distribution, supramolecular form, and arrangement of collagen types I and V in the chicken embryo corneal stroma were studied using electron microscopy, collagen type-specific monoclonal antibodies, and a preembedding immunogold method. Double-label immunoelectron microscopy with colloidal gold-tagged monoclonal antibodies was used to simultaneously localize collagen type I and type V within the chick corneal stroma. The results definitively demonstrate, for the first time, that both collagens are codistributed within the same fibril. Type I collagen was localized to striated fibrils throughout the corneal stroma homogeneously. Type V collagen could be localized only after pretreatment of the tissue to partially disrupt collagen fibril structure. After such pretreatments the type V collagen was found in regions where fibrils were partially dissociated and not in regions where fibril structure was intact. When pretreated tissues were double labeled with antibodies against types I and V collagen coupled to different size gold particles, the two collagens colocalized in areas where fibril structure was partially disrupted. Antibodies against type IV collagen were used as a control and were nonreactive with fibrils. These results indicate that collagen types I and V are assembled together within single fibrils in the corneal stroma such that the interaction of these collagen types within heterotypic fibrils masks the epitopes on the type V collagen molecule. One consequence of the formation of such heterotypic fibrils may be the regulation of corneal fibril diameter, a condition essential for corneal transparency.

  12. Influence of corneal hydration on optical coherence elastography

    Science.gov (United States)

    Twa, Michael D.; Vantipalli, Srilatha; Singh, Manmohan; Li, Jiasong; Larin, Kirill V.

    2016-03-01

    Corneal biomechanical properties are influenced by several factors, including intraocular pressure, corneal thickness, and viscoelastic responses. Corneal thickness is directly proportional to tissue hydration and can influence corneal stiffness, but there is no consensus on the magnitude or direction of this effect. We evaluated the influence of corneal hydration on dynamic surface deformation responses using optical coherence elastography (OCE). Fresh rabbit eyes (n=10) were prepared by removing the corneal epithelium and dropping with 0.9% saline every 5 minutes for 1 hour, followed by 20% dextran solution every 5 minutes for one hour. Corneal thickness was determined from structural OCT imaging and OCE measurements were performed at baseline and every 20 minutes thereafter. Micron-scale deformations were induced at the apex of the corneal tissue using a spatially-focused (150μm) short-duration (corneal thickness due to hydration process. Corneal thickness rapidly increased and remained constant following epithelium removal and changed little thereafter. Likewise, corneal stiffness changed little over the first hour and then decreased sharply after Dextran application (thickness: -46% [-315/682 μm] RR: - 24% [-0.7/2.88 ms-1]; GV: -19% [-0.6/3.2 m/s]). Corneal thickness and corneal stiffness (RR) were well correlated (R2 = .66). Corneal biomechanical properties are highly correlated with tissue hydration over a wide range of corneal thickness and these changes in corneal stiffness are quantifiable using OCE.

  13. High interocular corneal symmetry in average simulated keratometry, central corneal thickness, and posterior elevation.

    Science.gov (United States)

    Myrowitz, Elliott H; Kouzis, Anthony C; O'Brien, Terrence P

    2005-05-01

    The purpose of this study was to assess interocular corneal symmetry in average simulated keratometry, corneal thickness, and posterior corneal elevation. This retrospective analysis included data from scanning slit topography (Orbscan II; Bausch and Lomb, Rochester, NY) on 242 eyes from 121 consecutive patients undergoing standard evaluation for consideration of elective laser vision correction. The symmetry between the right and left eye in average simulated keratometry, minimum central corneal thickness, and posterior corneal elevation was assessed by comparative data analysis. Simulated keratometry ranged from 39.9 to 48.6 D. The interocular difference in average simulated keratometry was 0.47 D (standard deviation [SD] 0.43). The interocular Pearson correlation coefficient for average simulated keratometry was 0.90 (p central corneal thickness was 0.95 (p symmetry in all these parameters was very high in this group of consecutive patients. Asymmetry of these interocular parameters may warrant repeat clinical testing for accuracy and may predict corneal abnormalities. Normative data on posterior cornea elevation is presented. This study points out potentially clinically important high interocular corneal symmetry data in simulated keratometry, corneal thickness, and posterior corneal elevation.

  14. Human corneal fibrillogenesis. Collagen V structural analysis and fibrillar assembly by stromal fibroblasts in culture.

    Science.gov (United States)

    Ruggiero, F; Burillon, C; Garrone, R

    1996-08-01

    The stroma of the developing cornea is a highly organized extracellular matrix formed essentially by uniform, small-diameter collagen fibrils with constant interfibrillar spacing. Unlike the fibrillogenesis of chicken cornea, the assembly and maturation of human corneal fibrils have been poorly investigated. In the current study, the authors aimed to ascertain the heterotypic organization (collagens I and V) of the human corneal fibrils at the supramolecular level. To gain more insight into the molecular structure of collagen V, its cellular source, and its role in fibrillogenesis, the authors used cultured human corneal fibroblasts. The structure of human corneal stroma after brief homogenization of the tissue was analyzed by immunogold labeling using specific polyclonal antibodies and rotary shadowing. Biochemical, electron microscopic, and immunolabeling approaches were used to investigate the collagen fibril formation and the extracellular matrix synthesis using human corneal fibroblasts grown in culture as a model system. The authors showed that in human corneal stroma, collagen I is distributed uniformly along the striated fibrils, in contrast to collagen V, which could be identified only at sites at which the fibrils partially were disrupted. Rotary shadowing observations of the homogenate revealed that collagen VI, a major component of the human cornea, was associated closely with the collagen fibril surface. Corneal fibroblasts synthesize and deposit a collagenous matrix with fibrils resembling those of the human cornea in appearance and collagen composition. Biochemical data indicate that a high concentration (20% to 30%) of collagen V is synthesized by stromal fibroblasts and that collagen V molecules are processed similarly to matrix forms in which the extension peptides are retained on the molecules. The heterotypic nature (collagens I and V) of human corneal fibrils was determined. Results indicate that human corneal fibroblasts synthesize the major

  15. Effect of corneal contact lens wear on healing time and comfort post LGK for treatment of SCCEDs in boxers.

    Science.gov (United States)

    Wooff, Penelope J; Norman, Joanna C

    2015-09-01

    To determine whether dogs with spontaneous chronic corneal epithelial defects (SCCEDs) would heal faster and with an improved comfort score following linear grid keratotomy (LGK) combined with corneal contact lens (Acrivet(™) ) wear when compared to dogs having the LGK procedure alone. Prospective study. Twenty-seven boxer dogs (27 eyes) diagnosed with a SCCEDs were enrolled in the study. A LGK was performed on all dogs under dexmedetomidine and butorphanol sedation. Fourteen eyes were randomly assigned to receive a corneal contact lens. The dogs were evaluated typically at 7, 10, and 14 days or until the ulceration was healed. Client surveys were completed by the owners to subjectively assess comfort level and contact lens retention. Statistical analyses were performed utilizing generalized linear models and survival analysis with the Wilcoxon-Gehan test to evaluate group differences. All ulcers healed after the LGK procedure. Dogs with bandage contact lenses had a statistically significant (P = 0.035) decrease in median healing time (7 days (95% CI [7,9]) compared to those without contact lenses (10 days (95% CI [7,12])). There was no difference in subjective comfort score between treatment groups. Early contact loss occurred in 28.6% (95% CI [8.4%, 58.1%]) of dogs. All of the Acrivet(™) ruler corneal measurements agreed to within 1 mm (95% CI [87.2%, 100%]) of the Jameson caliper measurements of horizontal corneal diameter. The use of corneal bandage contact lenses significantly decreased median healing time although there was no effect on subjective comfort score. The Acrivet(™) ruler measurements were accurate in determining corneal diameter and therefore contact lens size. © 2014 American College of Veterinary Ophthalmologists.

  16. Corneal epithelium following penetrating keratoplasty.

    Science.gov (United States)

    Tsubota, K; Mashima, Y; Murata, H; Yamada, M; Sato, N

    1995-03-01

    This study was designed to observe any changes to the corneal epithelium after penetrating keratoplasty. The corneal epithelia of 26 patients were observed by specular microscopy 1 week, 1 month, 3 months, and 6 months following penetrating keratoplasty. After re-epithelialisation was confirmed by biomicroscopy 1 week after surgery, specular microscopy revealed many abnormal cells, including spindle shaped cells, nucleated cells, large cells, as well as irregular cell configurations. Although these abnormal findings tended to decrease with time, they were still present in some cases as much as 6 months postoperatively. Computerised morphometric analysis yielded mean cell areas of 1121 (SD 168) microns 2, 1139 (675) microns 2, 1712 (496) microns 2, and 1400 (377) microns 2 at 1 week, 1 month, 3 months, and 6 months respectively, all significantly greater than that of age matched controls (710 (151) microns 2). The shape factor decreased with time, but was still greater than the control level at 6 months. This study demonstrates that epithelial abnormalities persist longer than expected after penetrating keratoplasty, and that these subtle changes can be detected by specular microscopic observation, potentially allowing for modification and enhancement of the wound healing process.

  17. Intrastromal corneal ring implants for corneal thinning disorders: an evidence-based analysis.

    Science.gov (United States)

    2009-01-01

    The purpose of this project was to determine the role of corneal implants in the management of corneal thinning disease conditions. An evidence-based review was conducted to determine the safety, effectiveness and durability of corneal implants for the management of corneal thinning disorders. The evolving directions of research in this area were also reviewed. SUBJECT OF THE EVIDENCE-BASED ANALYSIS: The primary treatment objectives for corneal implants are to normalize corneal surface topography, improve contact lens tolerability, and restore visual acuity in order to delay or defer the need for corneal transplant. Implant placement is a minimally invasive procedure that is purported to be safe and effective. The procedure is also claimed to be adjustable, reversible, and both eyes can be treated at the same time. Further, implants do not limit the performance of subsequent surgical approaches or interfere with corneal transplant. The evidence for these claims is the focus of this review. The specific research questions for the evidence review were as follows: SafetyCorneal Surface Topographic Effects:Effects on corneal surface remodellingImpact of these changes on subsequent interventions, particularly corneal transplantation (penetrating keratoplasty [PKP])Visual AcuityRefractive OutcomesVISUAL QUALITY (SYMPTOMS): such as contrast vision or decreased visual symptoms (halos, fluctuating vision)Contact lens toleranceFunctional visual rehabilitation and quality of lifePatient satisfaction:Disease Process:Impact on corneal thinning processEffect on delaying or deferring the need for corneal transplantation TARGET POPULATION AND CONDITION Corneal ectasia (thinning) comprises a range of disorders involving either primary disease conditions such as keratoconus and pellucid marginal corneal degeneration or secondary iatrogenic conditions such as corneal thinning occurring after LASIK refractive surgery. The condition occurs when the normally round dome-shaped cornea

  18. [Applying deep lamellar keratoplasty in corneal disorders without endothelial abnormalities].

    Science.gov (United States)

    Wylegała, Edward; Wróblewska, Ewa Marta; Tarnawska, Dorota; Mierzwa, Marzena

    2003-01-01

    To present own experiences in the surgery of deep lamellar keratoplasty. 25 eye of 25 patients suffering from various corneal pathologies with preserved endothelium: 22 with keratoconus eyes, 2 with post-inflammatory scar and one eye with leucoma in Stevens-Johnson syndrome. Mean follow-up was 25.5 months (from 6 to 32). Main outcome measures were Non-Corrected and Best Corrected Visual Acuity (NCVA, BCVA), astigmatism, refractive error, IOP and corneal transparency. The surgery was performed in general anesthesia. In majority of cases the recipient stroma was trephined to a depth of 70% with 7.5 mm diameter vacuum trephine. In cases of intraoperative perforation of Descemet membrane with shallow anterior chamber we converted the procedure into penetrating keratoplasty. The donor lenticule was trephined in the artificial chamber with the 0.5 mm oversized manual trephine to a depth of 90%. In two cases after DLK was finished, limbal stem cell grafting was additionally performed. Postoperative NCVA ranged from 0.01 to 0.8 and BCVA from 0.1 to 0.8. Astigmatism ranged from 0.5 to 10.0 D. Refractive error ranged from -8.0 to +1.0 D. In follow-up period all grafts maintained transparent. The complications were mainly intraoperative perforations of Descemet membrane (9 cases): in 7 cases we convert the procedure into penetrating keratoplasty. In 2 cases the double chamber-forming was observed: in one case on 7 day following surgery the penetrating keratoplasty was performed, in other a spontaneous attachment was observed. We also observed loose sutures in 2 cases, inflammatory infiltrates in one case. Two cases of ocular hypertension was successfully treated by medication. Deep lamellar keratoplasty is an effective procedure for treating various diseases of corneal stroma with unaffected endothelium.

  19. Current treatment options for corneal ectasia.

    Science.gov (United States)

    Tan, Donald T H; Por, Yong-Ming

    2007-07-01

    The approach to the management of various forms of corneal ectasia is changing, with the advent of new surgical and nonsurgical options. The purpose of this review is to summarize and evaluate relevant studies on new treatments for keratoconus, postrefractive surgery keratectasia, and peripheral ectatic corneal disorders. Various alternatives to corneal transplantation for the management of keratoconus aim to enhance corneal rigidity by means of nonsurgical collagen cross-linking, or with the use of intrastromal corneal ring segments, and studies suggest that these treatments may reduce astigmatism or ectatic progression to varying degrees. Recent developments in anterior lamellar keratoplasty enable targeted replacement or augmentation of corneal stroma without replacement of endothelium, and include procedures such as deep anterior lamellar keratoplasty, microkeratome or laser-assisted anterior lamellar surgery, and peripheral tectonic lamellar keratoplasty procedures demonstrate successful reinforcement of peripheral stroma to reduce astigmatism. These new forms of surgery are viable alternatives to conventional penetrating keratoplasty and bring added safety profiles for long-term visual rehabilitation and restoration of tectonic integrity in central and peripheral forms of corneal ectasia.

  20. Factors Affecting Corneal Hysteresis in Taiwanese Adults.

    Science.gov (United States)

    Wang, Jia-Kang; Huang, Tzu-Lun; Pei-Yuan Su; Chang, Pei-Yao

    2015-09-01

    To investigate the correlation of various corneal hysteresis (CH) factors in Chinese adults. From January 2009 to November 2011, the healthy right eyes of a total of 292 adults were recruited into the study. Goldmann-correlated intraocular pressure (IOPG) and CH were measured using an ocular response analyzer (ORA). Central corneal thickness was measured using the ORA's integrated handheld ultrasonic pachymeter. The IOLMaster was used to obtain the ocular biometric measurements including axial length, anterior chamber depth, and keratometric values. The Pearson correlation coefficient was used to test correlations between CH and quantitative factors. The chi-square test was used to detect differences in categorical values. Longer axial length (P = 0.0001), lower IOPG (P = 0.03), older age (P = 0.003), and thinner central corneal thickness (P = 0.0001) were significantly associated with lower CH. The anterior chamber depth (P = 0.34), gender (P = 0.23), and corneal curvature (P = 0.18) had no relationship to CH. Various factors including axial length, intraocular pressure, age, and central corneal thickness can affect measurement of corneal biomechanical properties in Chinese adults. But the anterior chamber depth, gender, and corneal curvature were irrelevant to CH.

  1. Analysis of ethanol effects on corneal epithelium.

    Science.gov (United States)

    Oh, Joo Youn; Yu, Ji Min; Ko, Jung Hwa

    2013-06-04

    Ethanol is widely used in ocular surface surgeries and for the treatment of corneal diseases. However, ethanol is a toxic agent that is related to the development of a number of alcohol-related diseases. Despite the common use of ethanol for therapeutic purposes in ophthalmology, effects of ethanol on the ocular surface have been poorly defined. Hence, we performed this study to investigate effects of ethanol on corneal epithelium from various aspects. We exposed corneal epithelial cells in culture to different concentrations of ethanol for 30 seconds and evaluated the cells for toxicity, survival, and expression of cell-specific markers and inflammatory cytokines at 24, 48, and 72 hours after ethanol exposure. We found that ethanol markedly decreased the viability of cells in a concentration-dependent manner by causing cell lysis, suppressing proliferation, and inducing apoptosis. Also, expression of corneal epithelial cell-specific markers, both stem cell and differentiation markers, was significantly reduced by ethanol exposure. Expression of proinflammatory cytokines and chemokines was highly increased in corneal epithelial and stromal cells that were exposed to ethanol. Together, data suggest that brief exposure of the corneal surface to ethanol may have long-term effects by disrupting the integrity of corneal epithelium and generating inflammation, both of which are precursors to a number of ocular surface diseases.

  2. Electrospun Scaffolds for Corneal Tissue Engineering: A Review

    OpenAIRE

    Bin Kong; Shengli Mi

    2016-01-01

    Corneal diseases constitute the second leading cause of vision loss and affect more than 10 million people globally. As there is a severe shortage of fresh donated corneas and an unknown risk of immune rejection with traditional heterografts, it is very important and urgent to construct a corneal equivalent to replace pathologic corneal tissue. Corneal tissue engineering has emerged as a practical strategy to develop corneal tissue substitutes, and the design of a scaffold with mechanical pro...

  3. Chondroitin Sulfate-Based Biocompatible Crosslinker Restores Corneal Mechanics and Collagen Alignment.

    Science.gov (United States)

    Wang, Xiaokun; Majumdar, Shoumyo; Ma, Garret; Sohn, Jeeyeon; Yiu, Samuel C; Stark, Walter; Al-Qarni, Awad; Edward, Deepak P; Elisseeff, Jennifer H

    2017-08-01

    To evaluate the crosslinking effect of functionalized chondroitin sulfate (CS) in an ex vivo rabbit cornea model. Chondroitin sulfate molecules were chemically modified with the N-hydroxysuccinimide (NHS) group. Enucleated rabbit eyes were crosslinked with 2, 5, or 10 mg/mL CS-NHS solution for 30 or 60 minutes. The CS-NHS penetration, corneal swelling ratio, Young's modulus, and ultrastructure of the crosslinked corneas were characterized. In addition, rabbit corneas were further treated with a collagenase-chondroitinase solution to create an ex vivo keratoconus (KC)-like model. The KC model corneas were crosslinked with a standard riboflavin-ultraviolet (UV) method or alternatively with CS-NHS. Corneal mechanics, ultrastructure, and keratocyte gene expression were evaluated after UV and CS-NHS crosslinking. CS-NHS effectively penetrated into the corneal stroma within 60 minutes of treatment initiation. CS-NHS crosslinking reduced the swelling ratio by 35%, increased Young's modulus by 20%, and increased collagen fibril diameter and density. CS-NHS crosslinking improved corneal mechanics of KC model corneas to levels comparable to those with UV crosslinking. Moreover, CS-NHS crosslinking demonstrated significant downregulation of proinflammatory gene expression of keratocytes, indicating a potential protective effect imparted by CS-NHS during crosslinking. Our results demonstrated that CS-NHS can reinforce normal and KC model corneal mechanics, and restore collagen density and alignment in KC model corneas without causing extensive keratocyte apoptosis and proinflammatory gene upregulation. Therefore, CS-NHS crosslinking can potentially provide an effective, safe, and biocompatible means of corneal reinforcement.

  4. Current concepts and techniques in corneal transplantation.

    Science.gov (United States)

    Laibson, Peter R

    2002-08-01

    The corneal endothelium is the most important single layer in corneal transplantation. In his Castroviejo Lecture, William Bourne, MD, summarizes his work on the corneal endothelium and its importance to corneal transplantation. Almost half the corneal transplants performed in the United States are done so because of malfunctioning, diseased, or absent endothelial cells. If just this layer could be transplanted, the long wait for better vision after keratoplasty (up to two years in some countries) can be eliminated, as well as the problems of epithelial and subepithelial graft rejection. The significant astigmatism after keratoplasty could also be reduced. Transplantation of the endothelium in deep lamellar keratoplasty is being done in limited fashion throughout the world and the first patients have now been done in the United States. In many countries where corneal tissue is difficult to obtain, keratoplasty is only performed on one eye, even though both eyes may need it. One article this year discusses binocular vision recovery in bilateral keratoplasty and the objective and subjective improvements after bilateral keratoplasty. Patients who are bilaterally blind from diseases such as Stevens-Johnson syndrome, and ocular pemphigoid have little hope of visual recovery from conventional corneal transplants. The use of a keratoprosthesis to bypass the totally abnormal conjunctival surface has helped many people in the past. The preoperative prognostic categories of patients who may benefit from keratoprosthesis has been carefully reviewed in a large number of keratoprosthesis patients and this information will help ophthalmologists decide who will benefit the most benefit from keratoprosthesis. This year, articles on corneal transplantation after conjunctival flaps, suture-related complications in keratoplasty, the implantation of an intraocular lens after penetrating keratoplasty, and long-term results of penetrating keratoplasty with glaucoma drainage tube

  5. Corneal Biomechanical Properties in Rheumatoid Arthritis.

    Science.gov (United States)

    Can, Mehmet Erol; Erten, Sukran; Can, Gamze Dereli; Cakmak, Hasan Basri; Sarac, Ozge; Cagil, Nurullah

    2015-11-01

    To investigate the variations in biomechanical properties of the cornea in rheumatoid arthritis (RA) patients. A total of 53 RA patients, and 25 healthy individuals (control group) were enrolled. Rheumatoid arthritis patients were classified as in active phase (group 1; n=24) or in remission phase (group 2; n=29). Corneal biomechanical parameters including corneal hysteresis (CH), corneal resistance factor (CRF), corneal compensated intraocular pressure (IOPcc), and Goldmann-correlated IOP (IOPg) were measured with the Reichert Ocular Response Analyzer. Topographical measurements, including central corneal thickness (CCT), anterior chamber depth, iridocorneal angle, and corneal volume were measured using a Sirius corneal topographer. The mean CH was 9.43±1.17 mm Hg in group 1, 9.42±1.84 mm Hg in group 2, and 10.47±1.68 mm Hg in the control group (P=0.03). The mean IOPcc was 17.85±3.2 mm Hg in group 1, 17.95±3.49 mm Hg in group 2, and 15.36±3.11 mm Hg in the control group (P=0.008). The CH showed a significant positive correlation with CRF (P=0.000, r=0.809) and CCT (P=0.000, r=0.461), and a significant negative correlation with IOPcc (P=0.000, r=-0.469). Decrease in the mean CH measurements indicates that ultrastructural changes in the cornea may occur in the active phase, and these changes persist in the remission period. In addition, IOPcc is significantly affected by the corneal biomechanical properties. In RA patients, it is important to control the corneal parameters and IOP measurements against the irreversible changes on the optic nerve.

  6. Effect of nylon suture diameter on induced astigmatism after phacoemulsification.

    Science.gov (United States)

    Mendívil, A

    1997-10-01

    To prospectively compare the clinical results of 10-0 and 9-0 monofilament nylon sutures after phacoemulsification with poly(methyl methacrylate) intraocular lens implantation through a 4.0 mm cruciate incision. Department of Ophthalmology, Ramón y Cajal Hospital, Madrid, Spain. One hundred eyes with cataract were randomly assigned to have surgery using a 10-0 or a 9-0 nylon suture. Except for suture diameter, identical surgical methods were used in every case. Data on uncorrected visual acuity, keratometry and postoperative astigmatism were analyzed up to 12 months after surgery. Both groups had similar uncorrected visual acuity. Mean postoperative corneal astigmatism was against the rule in the 10-0 nylon suture group and with the rule in the 9-0 nylon suture group. Significant differences were found between groups (P suture diameters offered satisfactory clinical results. Patients with preoperative with-the-rule astigmatism might benefit from 10-0 nylon sutures and those with preoperative against-the-rule astigmatism, from 9-0 nylon sutures.

  7. Technology needs for corneal transplant surgery

    Science.gov (United States)

    Vaddavalli, Pravin K.; Yoo, Sonia H.

    2011-03-01

    Corneal transplant surgery has undergone numerous modifications over the years with improvements in technique, instrumentation and eye banking. The main goals of corneal transplantation are achieving excellent optical clarity with long-term graft survival. Penetrating, anterior and posterior lamellar surgery along with femtosecond laser technology have partially met these goals, but outcomes are often unpredictable and surgeon dependent. Technology to predictably separate stroma from Descemet's membrane, techniques to minimize endothelial cell loss, improvements in imaging technology and emerging techniques like laser welding that might replace suturing, eventually making corneal transplantation a refractively predictable procedure are on the wish list of the cornea surgeon.

  8. The Effect of Smoking on Corneal Biomechanics.

    Science.gov (United States)

    Kilavuzoglu, Ayse Ebru; Celebi, Ali Riza Cenk; Altiparmak, Ugur Emrah; Cosar, Cemile Banu

    2017-01-01

    To determine the effect of smoking on corneal biomechanical behavior. The medical records of consecutive patients that presented to the ophthalmology department were reviewed. History of smoking and ophthalmological examination findings were recorded. The smoking group met the following criteria: a clear history of and present smoking habit, negative history of corneal disease and surgery, ocular response analyzer measurement at the time of examination, and a waveform score ≥3.7. Nonsmokers (never smoked or quit smoking ≥6 months earlier) that met the same criteria constituted the control group. Corneal biomechanical parameters were measured using ocular response analyzer. Data were analyzed using Pearson's χ(2) test, Mann-Whitney U test, and Spearman's correlation coefficient. The smoking group included 166 eyes of 166 patients with a mean age of 38.7 ± 11.95 years, and the control group consisted of 170 eyes of 170 patients with a mean age of 38.40 ± 12.2 years. Mean cumulative smoking dose in the smoking group was 9.59 ± 11.87 pack-years (0.04- 75.00). There was no significant correlation between cumulative smoking dose and corneal hysteresis and corneal resistance factor (P = 0.382 and 0.074, respectively). There were no significant differences in corneal hysteresis or the corneal resistance factor between the two groups (P > 0.05). There was no significant difference in corneal hysteresis between those in the smoking group aged 18-44 years and those aged 45-64 years (P = 0.258), whereas in the control group mean corneal hysteresis was significantly lower in the 45-64 year olds than in the 18-44 year olds (P = 0.034). Although there was no significant difference in corneal biomechanics between smoking and control groups, the decrease in corneal hysteresis with aging was less apparent in the smoking group, which may be due to the potential changes in the cornea's microstructure induced by smoking during aging and the effect of smoking in aged corneal

  9. Should nylon corneal sutures be routinely removed?

    Science.gov (United States)

    Jackson, H.; Bosanquet, R.

    1991-01-01

    Three groups of patients who had undergone cataract extraction through a corneal incision closed with 10/0 nylon sutures one, two, and three years previously were recalled to determine the incidence of suture related complications. Broken corneal sutures were found in 87.5% of patients after two years and 90% after three years and were causing symptoms in over half the patients. It is recommended that 10/0 nylon corneal sutures be routinely removed no later than one year after surgery. Images PMID:1751460

  10. Clinical study on human lamellar keratoplasty for fungal corneal ulcers with porcine acellular corneal stroma

    OpenAIRE

    Fu-Hong Liao; Zi-Zhong Yu; Bin Hu

    2017-01-01

    AIM: To observe the transplantation of acellular porcine corneal stroma on the treatment of superficial keratitis by drug-resistant fungal. METHODS: We performed a retrospective analysis of 16 cases of fungal keratitis received the transplantation of acellular porcine corneal matrix from June 2015 to March 2016 with a follow-up of 6mo. We analyzed on items as postoperative visual acuity, corneal graft status, postoperative recurrence and postoperative complications. RESULTS: We observed a hea...

  11. Corneal-Wavefront guided transepithelial photorefractive keratectomy after corneal collagen cross linking in keratoconus

    OpenAIRE

    Camellin, Massimo; Guidotti, Jacopo Maria; Arba Mosquera, Samuel

    2016-01-01

    Purpose To evaluate the efficacy and safety of Corneal-Wavefront guided transepithelial photorefractive keratectomy (TransPRK) after corneal collagen cross linking (CXL) in keratoconic patients. Methods In this retrospective, non-comparative, consecutive case series, 39 keratoconic eyes underwent Corneal-Wavefront guided TransPRK for the correction of aberrations at least 4 months after conventional CXL at SEKAL Rovigo Microsurgery Centre, Rovigo, Italy. Two eyes (5%) underwent a secondary la...

  12. Role of Corneal Epithelium in Riboflavin/Ultraviolet-A Mediated Corneal Cross-Linking Treatment in Rabbit Eyes

    OpenAIRE

    Xiangchen Tao; Haiqun Yu; Yong Zhang; Zhiwei Li; Vishal Jhanji; Shouxiang Ni; Ya Wang; Guoying Mu

    2013-01-01

    Purpose. To evaluate the role of corneal epithelium in riboflavin/ultraviolet-A (UVA) mediated corneal collagen cross-linking treatment. Methods. Fifty New Zealand rabbits were divided into 5 groups: UVA treatment with or without corneal epithelium, UVA+riboflavin treatment with or without corneal epithelium, and control without any treatment. All rabbits were sacrificed after irradiation and subsequently 4?mm???10?mm corneal strips were harvested for biomechanical evaluation. Results. UVA ir...

  13. Ultrastructure of the posterior corneal stroma.

    Science.gov (United States)

    Schlötzer-Schrehardt, Ursula; Bachmann, Bjoern O; Tourtas, Theofilos; Torricelli, Andre A M; Singh, Arun; González, Sheyla; Mei, Hua; Deng, Sophie X; Wilson, Steven E; Kruse, Friedrich E

    2015-04-01

    To reinvestigate the ultrastructure of the posterior stroma of the human cornea and to correlate the findings with the stromal behavior after big-bubble creation. Observational consecutive 3-center case series. Fresh corneoscleral buttons from human donors (n = 19) and organ-cultured corneoscleral buttons (n = 10) obtained after Descemet's membrane endothelial keratoplasty. Corneal specimens were divided into central (3 mm), mid peripheral (8 mm), and peripheral parts by trephination and processed for transmission electron microscopic and immunohistochemical analyses. A big bubble was created by air injection into the stroma of organ-cultured corneas before fixation. The distance of keratocytes to Descemet's membrane, number of collagen lamellae between keratocytes and Descemet's membrane, diameter and arrangement of collagen fibrils, thickness of stromal lamella created by air injection, and immunopositivity for collagen types III, IV, and VI. Stromal keratocytes were observed at variable distances from Descemet's membrane, increasing from 1.5 to 12 μm (mean, 4.97±2.19 μm) in the central, 3.5 to 14 μm (mean, 8.03±2.47 μm) in the midperipheral, and 4.5 to 18 μm (mean, 9.77±2.90 μm) in the peripheral regions. The differences in mean distances were significant (P collagen lamellae between Descemet's membrane and most posterior keratocytes varied from 2 to 10 and the diameter of collagen fibrils averaged 23.5±1.8 nm and corresponded with that of the remaining stroma. A thin layer (0.5-1.0 μm thick) of randomly arranged, unaligned collagen fibers, which was positive for collagen types III and VI, was observed at the Descemet-stroma interface. The residual stromal sheet separated by air injection in 8 of 10 donor corneas varied in thickness from 4.5 to 27.5 μm, even within individual corneas (≤3-fold), and was composed of 5 to 11 collagen lamellae that revealed keratocytes on their anterior surface and in between. Barring an anchoring zone of interwoven

  14. Novel characterization of lymphatic valve formation during corneal inflammation.

    Directory of Open Access Journals (Sweden)

    Tan Truong

    Full Text Available Lymphatic research has progressed rapidly in recent years. Though lymphatic dysfunction has been found in a wide array of disorders from transplant rejection to cancer metastasis, to date, there is still little effective treatment for lymphatic diseases. The cornea offers an optimal site for lymphatic research due to its accessible location, transparent nature, and lymphatic-free but inducible features. However, it still remains unknown whether lymphatic valves exist in newly formed lymphatic vessels in the cornea, and how this relates to an inflammatory response. In this study, we provide the first evidence showing that lymphatic valves were formed in mouse cornea during suture-induced inflammation with the up-regulation of integrin alpha 9. The number of corneal valves increased with the progression of inflammatory lymphangiogenesis. Moreover, we have detected lymphatic valves at various developmental stages, from incomplete to more developed ones. In addition to defining the average diameter of lymphatic vessels equipped with lymphatic valves, we also report that lymphatic valves were more often located near the branching points. Taken together, these novel findings not only provide new insights into corneal lymphatic formation and maturation, but also identify a new model for future investigation on lymphatic valve formation and possibly therapeutic intervention.

  15. Clinical assessment of the soft corneal contact lens on corneal epithelium defect after vitrectomy

    Directory of Open Access Journals (Sweden)

    Meng-Su Tang

    2017-03-01

    Full Text Available AIM: To investigate the effect of soft corneal contact lens on the recovery of corneal epithelial defects and the comfort in patients with diabetic retinopathy after vitrectomy. METHODS: Twenty patients(20 eyeswith diabetic retinopathy whose corneal epithelium defected after vitrectomy were randomly divided into 2 groups. The trial group(10 eyesreceived the combination treatment of wearing soft corneal contact lenses and eyedrops to promote corneal epithelial repair, and the control group(10 eyesonly received eyedrops. The corneal epithelial healing time was observed postoperatively. And the scores of the comfort in patients between two groups were compared. RESULTS: The average duration of corneal epithelial defects was 4.1±1.20d in the trial group, and 14.2±6.07d in the control group, which was statistically significant different between the two groups(PP>0.05. CONCLUSION: The soft corneal contact lens could effectively treat patients with corneal epithelial defects after vitrectomy, and improve their comfort.

  16. Correlation of both corneal surfaces in corneal ectasia after myopic LASIK.

    Science.gov (United States)

    Peinado, Teresa Fernández; Piñero, David P; López, Ignacio Alcaraz; Alio, Jorge L

    2011-04-01

    We report a case of corneal ectasia in a 25-year-old man after myopic laser in situ keratomileusis in which a complete characterization of the corneal structure was performed by means of a Scheimpflug photography-based system. The patient presented in the ectatic eye with a subjective refraction of +0.50 to 6.00 × 100°, which with correction gave a visual acuity of 20/25. With the topographic analysis, corneal shapes from both corneal surfaces at the four different quadrants were found to be complementary, maintaining the meniscus-shaped profile of the cornea. This correlation between the anterior and posterior corneal surfaces was also confirmed with an optical tomography evaluation. Corneal biomechanics was also evaluated by means of the Ocular Response Analyzer (Reichert), which confirmed the biomechanical alteration. In summary, biomechanical changes leading to corneal ectasia in this case affected the global corneal structure, inducing alterations in the shape of both anterior and posterior corneal surfaces.

  17. [The effect of cataract and vitreoretinal surgery on central corneal thickness and corneal hysteresis].

    Science.gov (United States)

    Hager, A; Loge, K; Kutschan, A; Wiegand, W

    2008-03-01

    Intraocular irrigating solutions remain for several hours beyond the actual time of surgery in the eye. The irrigating solution ought to resemble biochemically aqueous humor and vitreous and offer protection for sensitive structures of the eye, such as the corneal endothelium. Impairment of the corneal endothelium may lead to corneal oedema and biomechanical alterations of the cornea. 54 eyes after pars-plana vitrectomy (PPV) in elective macular surgery were evaluated by measuring corneal thickness (CCT) using ultrasound pachymetry (20 MHz) and corneal hysteresis (CH) using the ocular response analyser (Reichert Ophthalmic Instruments, Buffalo, NY, USA). Measurements were performed not earlier than 2 weeks prior to surgery and 1 to 3 days after surgery. Results were compared to a control group (n = 39) and to 101 eyes after clear cornea cataract extraction (KAT). The two groups (PPV and KAT) did not differ with respect to age (p = 0.555). Corneal thickness has increased significantly in both groups (p corneal hysteresis decreased significantly postoperatively (p corneal thickness but also by biomechanical parameters such as corneal hysteresis.

  18. Corneal hysteresis, resistance factor, topography, and pachymetry after corneal lamellar flap.

    Science.gov (United States)

    Gatinel, Damien; Chaabouni, Slim; Adam, Pierre-Alexandre; Munck, Jacques; Puech, Michel; Hoang-Xuan, Thanh

    2007-01-01

    To measure prospectively the early changes in corneal hysteresis, topography, and pachymetry after the creation of a stromal flap cut without laser photoablation. A 37-year-old man was referred for a bioptic procedure to correct for compound myopic astigmatism in the left eye. A 159-microm-thick 8x8.5-mm superior hinged flap was created with a mechanical microkeratome in the left cornea. Changes in the corneal hysteresis, corneal resistance factor, Goldmann correlated intraocular pressure (lOP), corneal compensated IOP, anterior and posterior topography, and optical and ultrasound pachymetry were monitored prospectively before and at 1 hour, 1 day, 5 days, and 25 days after flap creation. The right eye served as a control. In the left eye, corneal hysteresis and corneal resistance factor decreased immediately after the flap cut and remained lower than preoperatively at 1 hour, 1 day, 5 days, and 25 days. Corneal compensated IOP varied significantly less than Goldmann correlated IOP in both eyes. Central flattening of the horizontal meridians was observed on the difference topography maps. The values of the left eye posterior best fit sphere increased after the flap cut. Increased central corneal thickness occurred immediately after the flap cut and decreased over time without returning to its preoperative value. The creation of a stromal flap can modify the biomechanical properties of the cornea, including a reduction in corneal hysteresis. The topographic changes were consistent with previously reported cases of flap cut in normal corneas.

  19. Repair of corneal ulcer or perforation using the corneal stromal lenticule

    Directory of Open Access Journals (Sweden)

    Xiao-Feng Hao

    2018-01-01

    Full Text Available AIM: To describe the outcomes of corneal stromal lenticules in repairing of corneal ulcer and/or perforation. METHODS: This was a retrospective chart review of 6 eyes of 6 patients from January to June 2017,who underwent corneal ulcer repair with the corneal, stromal lenticules harvested from femtosecond laser refractive surgery and kept in pure glycerin for use. Three cases of infectious corneal ulcers were bacterial, fungal, and infection with foreign bodies in corneal deep layer, one each. The other 3 were corneal ulcer perforation. Making sure no air bubble between donor graft and Descemet membrane. The mean follow-up time was 3.71±1.56mo(range 1-6mo. RESULTS: All eyes were successfully treated under control of infection without intra-operative complications, and early postoperative evaluation showed a clear graft in all cases. The last follow-up visit showed the mean best corrected visual acuity(VAsignificantly improved after surgery. There was significant difference from 0.48±0.12 to 1.50±0.08(PCONCLUSION: The preliminary results suggest that the use of corneal stromal lenticules may be a safe and effective surgical alternative for corneal ulcer, even though the long-term outcome of the graft needs to be further observed.

  20. Association between culture results of corneal scrapings and culture and histopathology results of corneal tissues in therapeutic keratoplasty.

    Science.gov (United States)

    Das, Sujata; Sharma, Savitri; Priyadarshini, Omega; Sahu, Srikant K; Kar, Sarita; Vemuganti, Geeta K

    2011-09-01

    To correlate the culture results of corneal scrapings with culture and histopathology results of corneal tissues in therapeutic keratoplasty. A retrospective analysis of the culture results of corneal scrapings and corneal tissues of eyes that received therapeutic penetrating keratoplasty at a tertiary eye care center between December 2006 and November 2008 was conducted. As per the preferred practice, those cases that did not respond to appropriate antimicrobial therapy and/or presented with a large infiltrate/perforation received therapeutic keratoplasty. The microbiology and histopathology findings of the corneal tissues were compared. Thirty-eight therapeutic keratoplasties were performed on 36 patients. Although all cases had histopathology and culture of the corneal tissue, corneal scrapings were not performed in 4 cases. Corneal scrapings and corneal tissues were culture-positive in 76% (26 of 34) and 60% (23 of 38) of cases, respectively. In 8 cases, the corneal scrapings and corneal tissues yielded identical organisms, whereas different organisms grew in 4 cases. In 6 cases, the corneal tissues were culture-positive but the corneal scrapings were sterile. In 20 cases, the corneal tissues were culture-positive for fungus and also showed fungal filaments in their corresponding histopathology specimens. Corneal tissue culture can provide additional information in cases undergoing therapeutic keratoplasty. It helps to determine the management of patients after keratoplasty.

  1. Thrombomodulin promotes corneal epithelial wound healing

    National Research Council Canada - National Science Library

    Huang, Yi-Hsun; I, Ching-Chang; Kuo, Cheng-Hsiang; Hsu, Yun-Yan; Lee, Fang-Tzu; Shi, Guey-Yueh; Tseng, Sung-Huei; Wu, Hua-Lin

    2015-01-01

    To determine the role of thrombomodulin (TM) in corneal epithelial wound healing, and to investigate whether recombinant TM epidermal growth factor-like domain plus serine/threonine-rich domain (rTMD23...

  2. Femtosecond Lasers and Corneal Surgical Procedures.

    Science.gov (United States)

    Marino, Gustavo K; Santhiago, Marcony R; Wilson, Steven E

    2017-01-01

    Our purpose is to present a broad review about the principles, early history, evolution, applications, and complications of femtosecond lasers used in refractive and nonrefractive corneal surgical procedures. Femtosecond laser technology added not only safety, precision, and reproducibility to established corneal surgical procedures such as laser in situ keratomileusis (LASIK) and astigmatic keratotomy, but it also introduced new promising concepts such as the intrastromal lenticule procedures with refractive lenticule extraction (ReLEx). Over time, the refinements in laser optics and the overall design of femtosecond laser platforms led to it becoming an essential tool for corneal surgeons. In conclusion, femtosecond laser is a heavily utilized tool in refractive and nonrefractive corneal surgical procedures, and further technological advances are likely to expand its applications. Copyright 2017 Asia-Pacific Academy of Ophthalmology.

  3. Clear corneal incision in cataract surgery.

    Science.gov (United States)

    Al Mahmood, Ammar M; Al-Swailem, Samar A; Behrens, Ashley

    2014-01-01

    Since the introduction of sutureless clear corneal cataract incisions, the procedure has gained increasing popularity worldwide because it offers several advantages over the traditional sutured scleral tunnels and limbal incisions. Some of these benefits include lack of conjunctival trauma, less discomfort and bleeding, absence of suture-induced astigmatism, and faster visual rehabilitation. However, an increasing incidence of postoperative endophthalmitis after clear corneal cataract surgery has been reported. Different authors have shown a significant increase up to 15-fold in the incidence of endophthalmitis following clear corneal incision compared to scleral tunnels. The aim of this report is to review the advantages and disadvantages of clear corneal incisions in cataract surgery, emphasizing on wound construction recommendations based on published literature.

  4. Corneal biomechanical properties in thyroid eye disease

    National Research Council Canada - National Science Library

    Karabulut, Gamze Ozturk; Kaynak, Pelin; Altan, Cıgdem; Ozturker, Can; Aksoy, Ebru Funda; Demirok, Ahmet; Yılmaz, Omer Faruk

    2014-01-01

    The purpose of this study is to investigate the effect of thyroid eye disease (TED) on the measurement of corneal biomechanical properties and the relationship between these parameters and disease manifestations...

  5. Conjunctival intraepithelial neoplasia with corneal furrow degeneration

    Directory of Open Access Journals (Sweden)

    Pukhraj Rishi

    2014-01-01

    Full Text Available A 68-year-old man presented with redness of left eye since six months. Examination revealed bilateral corneal furrow degeneration. Left eye lesion was suggestive of conjunctival squamous cell carcinoma, encroaching on to cornea. Anterior segment optical coherence tomography (AS-OCT confirmed peripheral corneal thinning. Fluorescein angiography confirmed intrinsic vascularity of lesion. Patient was managed with "no touch" surgical excision, dry keratectomy without alcohol, cryotherapy, and primary closure. Pathologic examination of removed tissue confirmed clinical diagnosis. Management of this particular case required modification of standard treatment protocol. Unlike the alcohol-assisted technique of tumor dissection described, ethyl alcohol was not used for risk of corneal perforation due to underlying peripheral corneal thinning. Likewise, topical steroids were withheld in the post-operative period. Three weeks post-operatively, left eye was healing well. Hence, per-operative usage of absolute alcohol and post-operative use of topical steroids may be best avoided in such eyes.

  6. [Nanostructured bioplastic material for traumatic corneal injuries].

    Science.gov (United States)

    Kanyukov, V N; Stadnikov, A A; Trubina, O M; Yakhina, O M

    2015-01-01

    To substantiate the use of nanostructured bioplastic material for the treatment of traumatic eye injuries. The study enrolled 96 eyes of 48 rabbits and was carried out in 3 series of experiments, different in the type of induced corneal trauma: mechanical erosion, alkaline or acid burn. The animals were clinically monitored and sacrificed for morphological investigation at days 3, 7, 14, 30, and 90. The size of mechanical corneal erosions was repeatedly evaluated with fluorescein eye stain test. In the experimental group, Hyamatrix biomaterial was topically administered according to an original technique. In the controls, soft contact lenses were inserted and sutured. Complete closure of the epithelial defect with no impact on corneal properties was achieved in 3 days in the experimental group and in4 days in the control group. As for alkaline and acid corneal burns, experimental and control groups received Hyamatrix biomaterial and Solcoseryl eye gel correspondingly. In the experimental group of alkaline burn the defect closed by day 7, in the controls--by day 10-11. Acid-induced corneal edema also resolved by day 7 in the experimental group and by day 14 in the control group. 1. The results of this experimental and morphological study prove the hyaluronic acid-derived nanostructured bioplastic material effective in accelerating corneal re-epithelialization after mechanical erosions as compared with the controls. 2. Topical application of the hyaluronic acid-derived nanostructured bioplastic material shortens the exudative phase of inflammation, promotes corneal defect closure with formation of a more subtle opacification, and stimulates corneal restoration after chemical burns.

  7. IOL Power Calculation after Corneal Refractive Surgery

    OpenAIRE

    Maddalena De Bernardo; Luigi Capasso; Luisa Caliendo; Francesco Paolercio; Nicola Rosa

    2014-01-01

    Purpose. To describe the different formulas that try to overcome the problem of calculating the intraocular lens (IOL) power in patients that underwent corneal refractive surgery (CRS). Methods. A Pubmed literature search review of all published articles, on keyword associated with IOL power calculation and corneal refractive surgery, as well as the reference lists of retrieved articles, was performed. Results. A total of 33 peer reviewed articles dealing with methods that try to overcome the...

  8. Corneal collagen crosslinking for keratoconus. A review

    OpenAIRE

    M. M. Bikbov; V. K. Surkova

    2014-01-01

    Photochemical crosslinking is widely applied in ophthalmology. Its biochemical effect is due to the release of singlet oxygen that promotes anaerobic photochemical reaction. Keratoconus is one of the most common corneal ectasia affecting 1 in 250 to 250 000 persons. Currently, the rate of iatrogenic ectasia following eximer laser refractive surgery increases due to biomechanical weakening of the cornea. Morphologically and biochemically, ectasia is characterized by corneal layers thinning, co...

  9. Corneal biomechanical properties of patients with acromegaly.

    Science.gov (United States)

    Ozkok, Ahmet; Hatipoglu, Esra; Tamcelik, Nevbahar; Balta, Burcu; Gundogdu, Ahmet Sadi; Ozdamar, Mehmet Akif; Kadioglu, Pinar

    2014-05-01

    Growth hormone (GH) and insulin-like growth factor-1 (IGF-1) excess in acromegaly have various effects on many organs. The ophthalmologic effects of GH and IGF-1 excess have not yet been investigated in detail. The aim of the current study is to compare the corneal biomechanical properties of patients with acromegaly and those of healthy subjects. 45 patients with acromegaly (F/M=27/18) and 42 age-matched and gender-matched healthy individuals (F/M=24/18) were enrolled in this cross-sectional study. Central corneal thickness (CCT), corneal resistance factor (CRF), corneal hysteresis (CH), corneal compensated intraocular pressure (IOPcc) and Goldmann correlated IOPG were measured in patients with acromegaly and in healthy individuals using the Ocular Response Analyser (ORA). GH and IGF1 values were also determined in the study group. The mean CH and CRF values were higher in acromegalic patients (12.1±2.2 and 12.3±2.4, respectively) than in healthy subjects (11.0±1.6 and 10.8±1.5, respectively; for CH, p=0.014; for CRF, p=0.001). Mean IOPG measurement was higher in the acromegaly group than in the control group (p=0.017). There was no statistically significant difference in measured CCT (p=0.117) and IOPcc (p=0.594) values between acromegalic patients and healthy subjects. These findings indicate that acromegaly has target organ effects on the eye. Consequently, it can change corneal biomechanical properties such as corneal hysteresis and the CRF. Corneal biomechanical properties are known to affect the accuracy of IOP measurements. These findings should be taken into account when measuring IOP values in acromegaly patients, as IOP readings may be overestimated.

  10. Corneal Biomechanics Determination in Healthy Myopic Subjects

    Directory of Open Access Journals (Sweden)

    Kunliang Qiu

    2016-01-01

    Full Text Available Purpose. To determine the corneal biomechanical properties by using the Ocular Response Analyzer™ and to investigate potential factors associated with the corneal biomechanics in healthy myopic subjects. Methods. 135 eyes from 135 healthy myopic subjects were included in this cross-sectional observational study. Cornea hysteresis (CH, corneal resistance factor (CRF, cornea-compensated intraocular pressure (IOPcc, and Goldmann-correlated intraocular pressure (IOPg were determined with the Reichert Ocular Response Analyzer (ORA. Univariate and multivariate regression analyses were performed to investigate factors associated with corneal biomechanics. Results. The mean CH and CRF were 9.82±1.34 mmHg and 9.64±1.57 mmHg, respectively. In univariate regression analysis, CH was significantly correlated with axial length, refraction, central corneal thickness (CCT, and IOPg (r=-0.27, 0.23, 0.45, and 0.21, resp.; all with p≤0.015, but not with corneal curvature or age; CRF was significantly correlated with CCT and IOPg (r=0.52 and 0.70, resp.; all with p<0.001, but not with axial length/refraction, corneal curvature, or age. In multivariate regression analysis, axial length, IOPcc, and CCT were found to be independently associated with CH, while CCT and IOPg were associated with CRF. Conclusions. Both CH and CRF were positively correlated with CCT. Lower CH but not CRF was associated with increasing degree of myopia. Evaluation of corneal biomechanical properties should take CCT and myopic status into consideration.

  11. Corneal hysteresis in mucopolysaccharidosis I and VI.

    Science.gov (United States)

    Fahnehjelm, Kristina Teär; Chen, Enping; Winiarski, Jacek

    2012-08-01

    High intraocular pressure (IOP) and glaucoma are often suspected in patients with mucopolysaccharidosis (MPS). To determine corneal hysteresis (CH) and IOP in children with mucopolysaccharidosis I-Hurler (MPS I-H) and MPS VI. Clinical measurements with ocular response analyzer (ORA). In seven patients, five with MPS I-H treated with stem cell transplantation (SCT), and two with MPS VI, one treated with SCT and the other with enzyme therapy, the IOP was examined with ORA. Ocular response analyzer measurements were made at a median age of 8.7 years in the patients with MPS I-H and at a median age of 9.3 years in the patients with MPS VI. Earlier measurements had raised suspicion of high IOP in one patient. The ORA showed an increased CH and a falsely high IOP values in all 14 eyes. The recalculated IOPs were normal in all 14 eyes. Mild to severe corneal opacities were present in all 14 eyes. Optic disc areas, borders and cupping were clinically normal in the 12 of 14 eyes that were possible to examine. Severe corneal opacities hampered optic disc evaluation in the older patient with MPS VI. Three eyes in two patients had normal thickness of the retinal nerve fibre layer measured with scanning laser polarimetry with corneal compensation (GDx VCC). No patient was diagnosed or treated for glaucoma. The IOPs are often falsely high because of an increased resistance of the cornea and correlate to the extent of corneal clouding. In this small, cross-sectional study, it appears that corneal resistance is directly correlated with corneal clouding, although a longitudinal study that evaluates resistance as the cornea clears with treatment would provide more direct evidence that corneal deposits are directly related to resistance. A correct measured IOP can avoid unnecessary medical or surgical hypotensive treatment. © 2011 The Authors. Acta Ophthalmologica © 2011 Acta Ophthalmologica Scandinavica Foundation.

  12. Corneal Collagen Cross-Linking Outcomes: Review

    OpenAIRE

    Jankov II,Mirko R.; Jovanovic,Vesna; Delevic, Sladjana; Coskunseven, Efekan

    2011-01-01

    Keratoconus is a condition characterized by biomechanical instability of the cornea, presenting in a progressive, asymmetric and bilateral way. Corneal collagen cross-linking with riboflavin and UVA (CXL) is a new technique of corneal tissue strengthening that combines the use of riboflavin as a photo sensitizer and UVA irradiation. The studies showed that CXL was effective in halting the progression of keratoconus over a period of up to four years. The published studies also revealed a reduc...

  13. [An experimental research of recombinant human epidermal growth factor on corneal wound healing].

    Science.gov (United States)

    Zheng, R; Jin, X; Yang, B; Li, B; Li, L; Xu, Z; Zhu, H

    1998-05-01

    To investigate the effects of recombinant human epidermal growth factor (rhEGF) eye drops on corneal wound healing. Twenty-four white rabbits were randomly divided into 4 groups, 6 rabbits 12 eyes each. Anterior keratectomy of 8 mm in diameter and 1/3 cornea in thickness was performed on each eye. Each of the following concentrations of rhEGF: 1, 10, 100 microg/ml eye drops or normal saline (control) was applied four times daily for a week respectively for one group. The wound area was determined by computer imaging analysis. The mean epithelial healing rate of rhEGF 1, 10, 100 microg/ml groups was 9.31, 9.96, 9.31 mm(2)/day respectively, significantly greater than 8.11 mm(2)/day of the control group. The action of rhEGF of 10 microg/ml was somewhat better than that of 1 or 100 microg/ml, and no significant difference was noticed among the three rhEGF groups. Moderate inflammation and corneal neovascularization were induced in the rhEGF 100 microg/ml treated group. rhEGF 1 - 10 microg/ml can accelerate corneal wound healing in the rabbit with no adverse side-effects. It may be used to treat serious corneal trauma and ulcer clinically.

  14. Chick corneal development in vitro: diverse effects of pH on collagen assembly.

    Science.gov (United States)

    Bard, J B; Hulmes, D J; Purdom, I F; Ross, A S

    1993-08-01

    In vivo, the embryonic chick corneal epithelium lays down a stroma of collagen and proteoglycans whose fibrils are unusual as their diameter distribution peaks sharply about a mean of 20 nm. Such epithelia cultured on Nuclepore filters will also lay down a stroma containing 20 nm diameter fibrils, although there is only limited orthogonal organisation. We report here that collagen fibril morphology is critically dependent on the pH of the medium in which the corneal epithelium is cultured and that normal 20 nm diameter fibrils only assemble in a narrow band around neutral pH (approx. 6.9-7.4). At higher pH (7.6-8.1), fibrils in the distal region of the stroma more closely resemble those seen in non-corneal stroma as their diameters can be up to 200 nm even though fibrils near the basal lamina are only about 10 nm in diameter. At low pH (approx. 6.5), there are again wide fibrils, but with the hieroglyphic cross-sections typical of those seen in heritable disorders of N-terminal procollagen processing. Biochemical analysis by SDS-PAGE and fluorography confirms that N-terminal procollagen processing is deficient at this pH. At very low pH (approx. 5.8-6.2), there is little processing of procollagen and the stroma comprises filamentous material with the occasional banded structures typical of those formed by unprocessed procollagen at high concentration. Gel electrophoresis and peptide mapping showed that the collagens produced by the corneal epithelium of the primary stroma included types I, II and V and that total collagen production, as assessed by incorporation of [3H]proline, increased with pH, although the relative amounts of the different collagens produced remained essentially unchanged. While the biochemical data can account for the altered morphologies in the pH range 5.8 to 7.0, the sensitivity of fibril diameter to small changes around neutral pH remains unexplained, but points to the subtle, charge-based interactions necessary for the formation of 20 nm

  15. Intraocular pressure, corneal thickness, and corneal hysteresis in Steinert's myotonic dystrophy

    Directory of Open Access Journals (Sweden)

    Carlos Alexandre de A. Garcia Filho

    2011-06-01

    Full Text Available PURPOSE: Low intraocular pressure (IOP measured by Goldmann applanation tonometry (GAT is one of the ocular manifestations of Steinert's myotonic dystrophy. The goal of this study was to evaluate the corneal-compensated IOP as well as corneal properties (central corneal thickness and corneal hysteresis in patients with myotonic dystrophy. METHODS: A total of 12 eyes of 6 patients with Steinert's myotonic dystrophy (dystrophy group and 12 eyes of 6 age-, race-, and gender-matched healthy volunteers (control group were included in the study. GAT, Dynamic Contour Tonometry (DCT-Pascal and Ocular Response Analyzer (ORA were used to assess the IOP. Central corneal thickness was obtained by ultrasound pachymetry, and corneal hysteresis was analyzed using the ORA device. In light of the multiplicity of tests performed, the significance level was set at 0.01 rather than 0.05. RESULTS: The mean (standard deviation [SD] GAT, DCT, and corneal-compensated ORA IOP in the dystrophy group were 5.4 (1.4 mmHg, 9.7 (1.5 mmHg, and 10.1 (2.6 mmHg, respectively. The mean (SD GAT, DCT, and corneal-compensated ORA IOP in the control group was 12.6 (2.9 mmHg, 15.5 (2.7 mmHg, and 15.8 (3.4 mmHg, respectively. There were significant differences in IOP values between dystrophy and control groups obtained by GAT (mean, -7.2 mmHg; 99% confidence interval [CI], -10.5 to -3.9 mmHg; P<0.001, DCT (mean, -5.9 mmHg; 99% CI, -8.9 to -2.8 mmHg; P<0.001, and corneal-compensated ORA measurements (mean, -5.7 mmHg; 99% CI, -10.4 to -1.0 mmHg; P=0.003. The mean (SD central corneal thickness was similar in the dystrophy (542 [31] µm and control (537 [11] µm groups (P=0.65. The mean (SD corneal hysteresis in the dystrophy and control groups were 11.2 (1.5 mmHg and 9.7 (1.2 mmHg, respectively (P=0.04. CONCLUSIONS: Patients with Steinert's myotonic dystrophy showed lower Goldmann and corneal-compensated IOP in comparison with healthy individuals. Since central corneal thickness and

  16. Effects of axial length and corneal curvature on corneal biomechanics in elderly population

    Directory of Open Access Journals (Sweden)

    Sha-Sha Song

    2018-02-01

    Full Text Available AIM:To explore the corneal biomechanical properties of the elderly with different axial length(ALand corneal curvature by corneal visualization Scheimpflug Technology(Corvis ST. METHODS: Cross-sectional study. A total of 161 patients(297 eyesundergoing phacoemulsification were collected in this study. They were divided into 22-24mm, 24-26mm, more than 26mm groups according to axial length(190 eyes, 54 eyes and 53 eyes, respectively. Those of whom axial length was 22-24mm and the corneal curvature was 42-44D were divided into male and female groups(44 eyes and 49 eyes, respectively. Those of whom axial length was 22-24mm were divided into 42-44D group, more than 44D group according to corneal curvature(88 eyes, 102 eyes, respectively. Corvis ST was used to measure the biomechanical parameters of the cornea. The differences in the parameters between different groups were analyzed using the independent-samples t test or one-way analysis of variance and correlation analyses were performed using Pearson correlation analysis. RESULTS: When comparing the corneal biomechanical parameters, no statistically significant differences were found between male and female groups(P>0.05. The first applanation length and second applanation length among different corneal curvatures were statistically significant(PPr=0.429, 0.278; Pr=-0.291, -0.415; PCONCLUSION: The corneal curvature and ocular axial length may be the factors affecting the corneal biomechanical characteristics. The longer axial length, the thinner corneal thickness, the more easily the corneal is deformed, and with the increase of the axial length, intraocular pressure also increases.

  17. Corneal spherical aberration and its impact on choosing an intraocular lens for cataract surgery.

    Science.gov (United States)

    Al-Sayyari, Tarfah M; Fawzy, Samah M; Al-Saleh, Ahmed A

    2014-10-01

    To analyze the post operative results of targeting zero spherical aberration by selecting the best-fit aspheric intraocular lens (IOL), based on preoperative corneal spherical aberration of patients with phacoemulsification surgery. AlHokama Eye Specialist Center, Riyadh, Saudi Arabia. From the 1st of October 2012 until the 10th of April 2013. Fifty-three eyes, were subjected to phacoemulsification cataract surgery and divided into two groups, 34 eyes were implanted with aspheric IOLs based on their corneal spherical aberration targeting post operative zero total spherical aberration, whereas 19 eyes were implanted with neutral aspheric IOLs regardless of their corneal spherical aberrations (CSAs). As a pre and post routine examination, patients underwent: slit lamp testing, intraocular pressure (IOP) measuring, fundus examination, best spectacle corrected visual acuity (BSCVA), manifest refraction, pupillometry, axial length, contrast sensitivity, and corneal aberration measurement using Pentacam HR (OCULUS, Germany) at the 6-mm optical zone. Post operatively, visual function questionnaire (VF-14) was asked to all patients. Fifty-three eyes of 45 patients, whose age ranged from 45 to 90 years old, were available for analysis, the selected group was implanted with: Tecnis ZA9003 or ZCB00 (Abbott Medical Optics) IOLs in 17 eyes with corneal spherical aberration of more than 0.27 μm, AcrySof IQ SN60WF (Alcon Laboratories Inc.) IOLs were implanted in 4 eyes with CSA = (0.2-0.27) μm, and Rayner 970C, 920H or 620H IOLs with spherical aberration (SA) = 0 in 13 eyes with CSA less than 0.20 μm. The other group of 19 eyes was implanted with aspheric IOLs that have zero spherical aberration (Rayner 970C or 920H) regardless of their CSA. Root mean square (RMS) of total corneal aberration positively correlates to the pupil diameter (P = 0.0031, r = 0.3989). A low negative correlation was found between the corneal spherical aberration of the fourth ordered (Z40

  18. Intracorneal Ring Segments Implantation for Corneal Ectasia.

    Science.gov (United States)

    Giacomin, Natalia T; Mello, Glauco R; Medeiros, Carla S; Kiliç, Alyin; Serpe, Cristine C; Almeida, Hirlana G; Kara-Junior, Newton; Santhiago, Marcony R

    2016-12-01

    To provide an overview of the predictability, safety, and efficacy of intrastromal corneal ring segment (ICRS) implantation as a tool to improve visual acuity and its association with other techniques such as corneal collagen cross-linking (CXL), addressing biomechanical outcomes, models, surgical planning and technique, indications, contraindications, and complications in ectatic corneas. Literature review. ICRSs have been used to regularize the corneal shape and reduce corneal astigmatism and higher order aberrations, improve visual acuity to acceptable limits, and delay, or eventually prevent, a corneal keratoplasty in keratoconic eyes. Changes in ICRS thickness and size, combination of techniques, and the addition of femtosecond lasers to dissect more foreseeable channels represent an improvement toward more predictable results. Several studies have shown, over time, the long-term efficacy and safety of ICRS treatment for keratoconus, with variable predictability, maintaining the early satisfactory outcomes regarding visual acuity, keratometry, and corneal thickness. It is just as important to ensure that the disease will not progress as it is to improve the visual acuity. Therefore, many studies have shown combined techniques using ICRS implantation and CXL. Also, further limitations of ICRS implantation can be addressed when associated with phakic intraocular lens implantation and photorefractive keratectomy. ICRS implantation has shown effectiveness and safety in most cases, including combined procedures. In properly selected eyes, it can improve both refraction and vision in patients with keratoconus. [J Refract Surg. 2016;32(12):829-839.]. Copyright 2016, SLACK Incorporated.

  19. Lateral Growth Limitation of Corneal Fibrils and Their Lamellar Stacking Depend on Covalent Collagen Cross-linking by Transglutaminase-2 and Lysyl Oxidases, Respectively*

    Science.gov (United States)

    Wang, Lei; Uhlig, Philipp C.; Eikenberry, Eric F.; Robenek, Horst; Bruckner, Peter; Hansen, Uwe

    2014-01-01

    Corneal stroma contains an extracellular matrix of orthogonal lamellae formed by parallel and equidistant fibrils with a homogeneous diameter of ∼35 nm. This is indispensable for corneal transparency and mechanical functions. However, the mechanisms controlling corneal fibrillogenesis are incompletely understood and the conditions required for lamellar stacking are essentially unknown. Under appropriate conditions, chick embryo corneal fibroblasts can produce an extracellular matrix in vitro resembling primary corneal stroma during embryonic development. Among other requirements, cross-links between fibrillar collagens, introduced by tissue transglutaminase-2, are necessary for the self-assembly of uniform, small diameter fibrils but not their lamellar stacking. By contrast, the subsequent lamellar organization into plywood-like stacks depends on lysyl aldehyde-derived cross-links introduced by lysyl oxidase activity, which, in turn, only weakly influences fibril diameters. These cross-links are introduced at early stages of fibrillogenesis. The enzymes are likely to be important for a correct matrix deposition also during repair of the cornea. PMID:24265319

  20. Relationship among Corneal Biomechanics, Anterior Segment Parameters, and Geometric Corneal Parameters

    Directory of Open Access Journals (Sweden)

    Sadık Görkem Çevik

    2016-01-01

    Full Text Available Purpose. To investigate the relationship between corneal biomechanical parameters, anterior segment parameters, and geometric corneal parameters in a healthy Caucasian group. Methods. This retrospective study included the healthy eyes with best corrected visual acuity of at least 20/40 of 122 Caucasian subjects. The anterior segment parameters and geometric corneal parameters such as corneal volume, central corneal thickness, horizontal and vertical corneal radii, anterior and posterior steep, and flat keratometric values were measured with a Scheimpflug camera. The biomechanical properties were measured with Ocular Response Analyzer. Results. One hundred and twenty-two healthy Caucasian subjects (67 males, 55 females with a mean age of 45.32±20.23 were enrolled. Both corneal hysteresis and corneal resistance factor were positively correlated with CCT (r=0.529, p<0.001; r=0.638, p<0.001 and CV (r=0.635, p<0.001; r=0.579, p<0.001 and negatively correlated with age (r=-0.373, p<0.001; r=-0.249, p<0.001. Both in age-gender and multivariate models, CH and CRF had statistically significant negative association with the posterior steep K value. Conclusions. CH and CRF are negatively correlated with posterior steep and average posterior K values.

  1. The scale of substratum topographic features modulates proliferation of corneal epithelial cells and corneal fibroblasts.

    Science.gov (United States)

    Liliensiek, S J; Campbell, S; Nealey, P F; Murphy, C J

    2006-10-01

    The cornea is a complex tissue composed of different cell types, including corneal epithelial cells and keratocytes. Each of these cell types are directly exposed to rich nanoscale topography from the basement membrane or surrounding extracellular matrix. Nanoscale topography has been shown to influence cell behaviors, including orientation, alignment, differentiation, migration, and proliferation. We investigated whether proliferation of SV40-transformed human corneal epithelial cells (SV40-HCECs), primary human corneal epithelial cells (HCECs), and primary corneal fibroblasts is influenced by the scale of topographic features of the substratum. Using basement membrane feature sizes as our guide and the known dimensions of collagen fibrils of the corneal stroma (20-60 nm), we fabricated polyurethane molded substrates, which contain anisotropic feature sizes ranging from 200-2000 nm on pitches ranging from 400 to 4000 nm (pitch = ridge width + groove width). The planar regions separating each of the six patterned regions served as control surfaces. Primary corneal and SV40-HCEC proliferation decreased in direct response to decreasing nanoscale topographies down to 200 nm. In contrast to corneal epithelial cells, corneal fibroblasts did not exhibit significantly different response to any of the topographies when compared with planar controls at 5 days. However, decreased proliferation was observed on the smallest feature sizes after 14 days in culture. Results from these experiments are relevant in understanding the potential mechanisms involved in the control of proliferation and differentiation of cells within the cornea. (c) 2006 Wiley Periodicals, Inc

  2. [The influence of corneal hysteresis and corneal resistance factor on the measurement of intraocular pressure].

    Science.gov (United States)

    Hager, A; Schroeder, B; Sadeghi, M; Grossherr, M; Wiegand, W

    2007-06-01

    The influence of central corneal thickness (CCT) on the measurement of intraocular pressure (IOP) has been discussed extensively in recent years. The problem, however, has not been solved so far. In addition to CCT there are probably further biomechanical properties that play a role in IOP measurement. We wanted to find out whether these properties are related to Goldmann applanation tonometry (GAT), noncontact tonometry (NCT), or CCT. Biomechanical properties of the cornea such as corneal hysteresis (CH) and corneal resistance factor (CRF) can be measured with the Ocular Response Analyzer (ORA, Reichert Ophthalmic Instruments, Depew, NY, USA). Furthermore, a corneal compensated IOP (IOPcc) is given. We examined 156 normal eyes of 80 patients who did not show corneal pathology nor glaucoma. In each eye GAT, NCT, and ORA data as well as CCT were measured. Data were statistically analyzed with respect to agreement and the influence of CH and CRF on IOP measurement. In our patients the following average values were calculated: GAT 14.8+/-3.0 mmHg, NCT 16.4+/-3.9 mmHg, IOPcc 16.2+/-4.1 mmHg, CH 10.6+/-2.3 mmHg, CRF 10.9+/-2.4 mmHg, and CCT 557+/-36 microm. IOPcc was not related to CCT in normal eyes and the only IOP value related to CH (pcorneal thickness. Corneal hysteresis and corneal resistance factor provide further information about biomechanical properties of the cornea beyond central corneal thickness.

  3. Corneal Thickness During Corneal Collagen Cross-Linking with Isotonic Riboflavin Solution without Dextran

    Directory of Open Access Journals (Sweden)

    Refik Oltulu

    2014-08-01

    Full Text Available Objectives: To monitor the corneal thickness change during the dextran-free isotonic riboflavin solution-aided corneal collagen crosslinking procedure in keratoconus patients. Materials and Methods: Corneal thickness measurements during the corneal collagen cross-linking (CXL treatment for progressive keratoconus were evaluated. The corneal thickness measurements were obtained with ultrasonic pachymetry device at five different time points: 0, 15, and 30 minutes after epithelial removal and 15 and 30 minutes after the initiation of UVA irradiation. Results: Twenty-four eyes of 24 patients with progressive keratoconus were included in the study. The thinnest pachymetric values obtained at the 0, 15, and 30 minute measurements after corneal deepithelisation were 409.38±10.43 µm (383-435 µm, 434.56±17.68 µm (400-485 µm, and 457.44±21.78 µm (428-516 µm, respectively. Pachymetric values obtained at 15 and 30 minutes after UVA application to the cornea were 471.69±23.38 µm (439-526 µm and 482.63±23.69 µm (436-524 µm, respectively. The gradual increase was found to be statistically significant when each measurement was compared with the previous values (p<0.001. Conclusion: We found that the corneal thickness was not decreased during the CXL with dextran-free isotonic riboflavin solution; on the contrary, corneal thickness was increased regularly during the procedure. (Turk J Ophthalmol 2014; 44: 272-4

  4. Spatial and temporal variations in extracellular matrix of periocular and corneal regions during corneal stromal development.

    Science.gov (United States)

    Doane, K J; Ting, W H; McLaughlin, J S; Birk, D E

    1996-03-01

    The development of the avian corneal stroma occurs in discrete developmental stages. During this sequence of events, the neural crest-derived corneal fibroblast precursor cells are surrounded by distinct extracellular matrices which change both spatially and temporally. To elucidate the role of these matrices, extracellular matrix components in the periocular mesenchyme and cornea were analysed prior to and during migration and differentiation of corneal fibroblasts using antibodies against collagens, proteoglycans and glycoproteins. Previous work has concentrated on the matrix of the corneal stroma rather than the matrix of the periocular mesenchyme. Since the precursors of the corneal fibroblasts are present within the must migrate through the periocular mesenchyme prior to entry into the cornea proper, this environment was fully evaluated. The present study documents the matrix composition of both the cornea and periocular mesenchyme at developmental stages that are prior to and after initiation of corneal invasion by the corneal fibroblast precursors. Variations in matrix molecules comprising both the periocular mesenchyme and cornea were demonstrated. These include changes in the distribution of collagen types I, II, III, IV and VI; the proteoglycans decorin and lumican; as well as the adhesive glycoproteins tenascin, fibronectin and laminin. It is hypothesized that the variations in matrix localization are important in the regulation of cell migration and differentiation during normal corneal development. Any regulation is likely to involve a combination of components found in the extracellular matrices and therefore, a consideration of the matrix rather than isolated components is required.

  5. Intraocular pressure, corneal thickness, and corneal hysteresis in Steinert's myotonic dystrophy.

    Science.gov (United States)

    Garcia Filho, Carlos Alexandre de A; Prata, Tiago Santos; Sousa, Aline Katia Siqueira; Doi, Larissa Morimoto; Melo Jr, Luiz Alberto Soares

    2011-01-01

    Low intraocular pressure (IOP) measured by Goldmann applanation tonometry (GAT) is one of the ocular manifestations of Steinert's myotonic dystrophy. The goal of this study was to evaluate the corneal-compensated IOP as well as corneal properties (central corneal thickness and corneal hysteresis) in patients with myotonic dystrophy. A total of 12 eyes of 6 patients with Steinert's myotonic dystrophy (dystrophy group) and 12 eyes of 6 age-, race-, and gender-matched healthy volunteers (control group) were included in the study. GAT, Dynamic Contour Tonometry (DCT-Pascal) and Ocular Response Analyzer (ORA) were used to assess the IOP. Central corneal thickness was obtained by ultrasound pachymetry, and corneal hysteresis was analyzed using the ORA device. In light of the multiplicity of tests performed, the significance level was set at 0.01 rather than 0.05. The mean (standard deviation [SD]) GAT, DCT, and corneal-compensated ORA IOP in the dystrophy group were 5.4 (1.4) mmHg, 9.7 (1.5) mmHg, and 10.1 (2.6) mmHg, respectively. The mean (SD) GAT, DCT, and corneal-compensated ORA IOP in the control group was 12.6 (2.9) mmHg, 15.5 (2.7) mmHg, and 15.8 (3.4) mmHg, respectively. There were significant differences in IOP values between dystrophy and control groups obtained by GAT (mean, -7.2 mmHg; 99% confidence interval [CI], -10.5 to -3.9 mmHg; Pcorneal-compensated ORA measurements (mean, -5.7 mmHg; 99% CI, -10.4 to -1.0 mmHg; P=0.003). The mean (SD) central corneal thickness was similar in the dystrophy (542 [31] µm) and control (537 [11] µm) groups (P=0.65). The mean (SD) corneal hysteresis in the dystrophy and control groups were 11.2 (1.5) mmHg and 9.7 (1.2) mmHg, respectively (P=0.04). Patients with Steinert's myotonic dystrophy showed lower Goldmann and corneal-compensated IOP in comparison with healthy individuals. Since central corneal thickness and corneal hysteresis did not differ significantly between groups, the lower IOP readings documented in this

  6. Experimental Models for Investigating Intra-Stromal Migration of Corneal Keratocytes, Fibroblasts and Myofibroblasts

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    Lisha Ma

    2012-03-01

    Full Text Available Following laser vision correction, corneal keratocytes must repopulate areas of cell loss by migrating through the intact corneal stroma, and this can impact corneal shape and transparency. In this study, we evaluate 3D culture models for simulating this process in vitro. Buttons (8 mm diameter were first punched out of keratocyte populated compressed collagen matrices, exposed to a 3 mm diameter freeze injury, and cultured in serum-free media (basal media or media supplemented with 10% FBS, TGFb1 or PDGF BB. Following freeze injury, a region of cell death was observed in the center of the constructs. Although cells readily migrated on top of the matrices to cover the wound area, a limited amount of cell migration was observed within the constructs. We next developed a novel “sandwich” model, which better mimics the native lamellar architecture of the cornea. Using this model, significant migration was observed under all conditions studied. In both models, cells in TGFb and 10% FBS developed stress fibers; whereas cells in PDGF were more dendritic. PDGF stimulated the most inter-lamellar migration in the sandwich construct. Overall, these models provide insights into the complex interplay between growth factors, cell mechanical phenotypes and the structural properties of the ECM.

  7. The corneal volume and biomechanical corneal factors: Is there any orrelation?

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    Mohammad Reza Sedaghat

    2012-01-01

    Full Text Available Background: The aim of this study was to determine the correlation between corneal hysteresis (CH and the corneal resistance factor (CRF, which are both novel methods of analyzing ocular rigidity/elasticity, and various corneal cha-racteristics, mainly corneal volume in normal subjects. Methods: This cross-sectional study included 500 normal eyes of volunteers. An ocular response analyzer (ORA was used to measure CH and CRF. Patient age and the Pentacam-measured corneal volume (CV, posterior elevation, ante-rior elevation, corneal curvature, central corneal thickness (CCT, corneal thickness of apex (CTA, and corneal thinnest thickness (CTT were compared with CH and CRF. Statistical significance was defined at p < 0.05. Results: The mean CH and CRF for all eyes were 9.9 ± 1.4 mmHg and 10.1 ± 1.6 mmHg, respectively. The mean CVs of the 3, 5, 7, and 10 mm zones for all eyes were 3.8 ± 0.2 mm3, 11.2 ± 0.6 mm3, 24.3 ± 1.4 mm3, and 60.1 ± 3.5 mm3, respectively. The correlations between CV and the hysteresis or CRF were significant in all zones. The CV of the 7-mm zone had the strongest correlation with CH (r = 0.438 and the CV of the 5-mm zone had the strongest correlation with CRF (r = 0.574. Conclusions: CH and CRF correlate with CV. Moreover, the correlation between CV and CRF is stronger than that between CV and CH. The CV may be valuable for determining patient′s qualification for and predicting the outcome of refractive surgery. It would also be helpful in other cases in which corneal biomechanics are important.

  8. Reliability of the Effect of Artificial Anterior Chamber Pressure and Corneal Drying on Corneal Graft Thickness.

    Science.gov (United States)

    Romano, Vito; Steger, Bernhard; Chen, Jern Y; Hassaan, Sherif; Batterbury, Mark; Willoughby, Colin E; Ahmad, Sajjad; Elsheikh, Ahmed; Kaye, Stephen B

    2015-08-01

    To investigate the effect of artificial anterior chamber (AAC) pressure and corneal drying on the graft thickness in preparation for Descemet stripping automated endothelial keratoplasty. Twenty-seven corneoscleral discs were placed in an AAC. The AAC pressure (15, 45, 92, 109, and 198 mm Hg) was controlled using the height of an infusion bottle and a roller clamp. The endothelium was removed in 1 subgroup. Corneas were exposed to room air or repeatedly dried using cellulose spears. Central corneal thickness was measured every 90 seconds for the first 15 minutes and again at 20 minutes using an ultrasound pachymeter (SP-100, Tomey). There was a significant linear relationship between the corneal thickness and both AAC pressure and corneal drying. Very high coefficients of determination and narrow 95% confidence intervals were present, in particular for high pressures and drying. The rate of thinning increased with increasing pressure and drying to 1.6% per minute. At the maximum rate of thinning, a 10% reduction in corneal thickness occurred in 6 minutes or 100 μm in 8.8 minutes. Removal of the corneal endothelium reduced the rate of thinning to 0.3% per minute (R = 0.72). Increasing AAC pressure and corneal drying reduced the graft thickness at a very predictable rate. Adequate corneal thinning can be achieved by increasing the pressure in the AAC by closing the clamp followed by removal of the residual corneal epithelium and repeated drying with a cellulose spear for 5 to 10 minutes, depending on the initial corneal thickness. This method is simple and is both suitable for use in the eye bank and by the surgeon.

  9. 7 CFR 51.2656 - Diameter.

    Science.gov (United States)

    2010-01-01

    ... Standards for Grades for Sweet Cherries 1 Definitions § 51.2656 Diameter. Diameter means the greatest dimension measured at right angles to a line from the stem to the blossom end of the cherry. ...

  10. Human tears reveal insights into corneal neovascularization.

    Science.gov (United States)

    Zakaria, Nadia; Van Grasdorff, Sigi; Wouters, Kristien; Rozema, Jos; Koppen, Carina; Lion, Eva; Cools, Nathalie; Berneman, Zwi; Tassignon, Marie-José

    2012-01-01

    Corneal neovascularization results from the encroachment of blood vessels from the surrounding conjunctiva onto the normally avascular cornea. The aim of this study is to identify factors in human tears that are involved in development and/or maintenance of corneal neovascularization in humans. This could allow development of diagnostic tools for monitoring corneal neovascularization and combination monoclonal antibody therapies for its treatment. In an observational case-control study we enrolled a total of 12 patients with corneal neovascularization and 10 healthy volunteers. Basal tears along with reflex tears from the inferior fornix, superior fornix and using a corneal bath were collected along with blood serum samples. From all patients, ocular surface photographs were taken. Concentrations of the pro-angiogenic cytokines interleukin (IL)-6, IL-8, Vascular Endothelial Growth Factor (VEGF), Monocyte Chemoattractant Protein 1 (MCP-1) and Fas Ligand (FasL) were determined in blood and tear samples using a flow cytometric multiplex assay. Our results show that the concentration of pro-angiogenic cytokines in human tears are significantly higher compared to their concentrations in serum, with highest levels found in basal tears. Interestingly, we could detect a significantly higher concentration of IL- 6, IL-8 and VEGF in localized corneal tears of patients with neovascularized corneas when compared to the control group. This is the first study of its kind demonstrating a significant difference of defined factors in tears from patients with neovascularized corneas as compared to healthy controls. These results provide the basis for future research using animal models to further substantiate the role of these cytokines in the establishment and maintenance of corneal neovascularization.

  11. Phototherapeutic Keratectomy Outcomes in Superficial Corneal Opacities

    Directory of Open Access Journals (Sweden)

    Khalid Al Arfaj

    2011-01-01

    Full Text Available Purpose Compare the effectiveness of Phototherapeutic keratectomy (PTK in treatment corneal dystrophies versus superficial corneal scars: visual outcomes, recurrence rate and safety profile. Methods PTK was performed in 51 eyes of 51 patients. Data regarding the indications for PTK, ablation depth, symptomatic relief, pre-and postoperative best spectacle-corrected visual acuity (BSCVA, spherical equivalent changes, recurrence and complications were analyzed. The indications for PTK in our study were classified into two categories – group A: patients with corneal dystrophies (n = 23 and the other group B (n = 28 with other indications. Results The average age of the patients was 47 years (±16.4. The mean follow up period was 15.16 months (±10.01 months. Post operatively, there were no significant complications. While the overall BSCVA in the patients improved from 20/41 (0.484 to 20/32 (0.645, group A showed improvement from 20/35 (0.561 to 20/29 (0.687, as compared to group B in which BSCVA improved from 20/47 (0.421 to 20/33 (0.611. The most common indication in group A was granular corneal dystrophy (n = 10 and the most common indication in group B was post traumatic/infectious corneal scar or opacity (n = 10. Eighty-six percent (n = 44 of all patients had alleviation of symptoms. Recurrence of symptoms was seen in 3 eyes of recurrent corneal erosions which required retreatment. Conclusion PTK is a safe and effective procedure. The outcome of this study suggests that PTK improves BSCVA. PTK appears to improve ocular surface health. Furthermore, PTK can be recommended to most patients with corneal dystrophies as a treatment modality prior to other more invasive procedure (viz. penetrating keratoplasty.

  12. Evaluation of collagen foam, poly(l-lactic acid) nanofiber mesh, and decellularized matrices for corneal regeneration.

    Science.gov (United States)

    Aslan, Bahar; Guler, Selcan; Tevlek, Atakan; Aydin, Halil Murat

    2017-10-12

    Corneal tissue engineering efforts to obtain corneal tissue matrices through various types of materials for the replacement of damaged tissues. In this study, three different corneal constructs were prepared and evaluated in terms of morphological, optical, and biological characteristics. Type-I collagen was used to obtain collagen foam scaffolds through dehydrothermal crosslinking, while poly(l-lactic acid) (PLLA) was used to produce both random and aligned oriented electrospun corneal constructs. Bovine corneas were decellularized as third matrix. Software analyses showed that average pore size of collagen scaffolds was 88.207 ± 29.7 µm, while the average fiber diameter of aligned and random PLLA scaffolds were 0.69 ± 0.03 and 0.65 ± 0.03 μm, respectively. Degradation profiles revealed that collagen foam exhibits high degradation (20% mass loss) while electrospun PLLA scaffolds hold low degradation (9% mass loss) rates at day-28. Transmittance values of the obtained scaffolds were calculated as 92, 80, and 70% for collagen, PLLA, and decellularized cornea constructs, respectively. The evaluation of stromal keratocyte behavior on the constructs revealed that the cells exhibited their own morphology mostly on the aligned PLLA constructs, while they were mostly active on random PLLA electrospun corneal scaffolds. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017. © 2017 Wiley Periodicals, Inc.

  13. Height - Diameter predictive equations for Rubber (Hevea ...

    African Journals Online (AJOL)

    BUKOLA

    ABSTRACT. The importance of calibrating models on height-diameter relationship can never be over emphasized in predicting mean total height for trees when only diameter at breast height is measured traditionally. This study has evaluated a set of height-diameter models from twenty plots of Hevea brasilliensis plantation ...

  14. SOME TECHNIQUES IN CORNEAL GRAFTING

    African Journals Online (AJOL)

    1971-04-10

    Apr 10, 1971 ... trephine and results in a trephine hole with sides sloping inwards, and hence a donor disc with an inside diameter slightly less than outside (Fig. 1).' The eye holder or stand is well known, but we use here a cover (designed by Dr R. L H. Townsend) to fit over and clamp the eye, with the cornea exposed in a.

  15. Effects of riboflavin/UVA corneal cross-linking on keratocytes and collagen fibres in human cornea.

    Science.gov (United States)

    Mencucci, Rita; Marini, Mirca; Paladini, Iacopo; Sarchielli, Erica; Sgambati, Eleonora; Menchini, Ugo; Vannelli, Gabriella B

    2010-01-01

    To evaluate the effects of corneal cross-linking on keratocytes and collagen fibres in human corneas. Fifteen corneal buttons were examined. Ten were from patients with keratoconus submitted to penetrating keratoplasty and five of them were treated with cross-linking 6 months before penetrating keratoplasty. Five normal corneal buttons from healthy donors were used as controls. All samples were prepared for TUNEL assay and Western blot analysis for the detection of keratocyte apoptosis and immunohistochemical analysis for the morphological evaluation of keratocytes and collagen fibre diameter. Normal corneas exhibited no TUNEL-positive keratocytes and keratoconic and cross-linked corneas showed moderate apoptotic cells mainly in the anterior part of the stroma. This apoptotic trend was confirmed by the cleavage of poly (ADP-ribose) polymerase assessed using Western blot. The Ki-67 staining showed a significant increase in the keratocyte proliferation in cross-linked corneas compared with normal and keratoconus. In cross-linked corneas CD34-positive keratocytes were regularly distributed throughout the whole corneal stroma as in the control, and keratoconus was associated with patchy loss of immunoreactivity. The immunohistochemical analysis of collagen type I showed a significant increase in fibre diameter of cross-linked corneas compared with control and keratoconus. Corneal cross-linking leads to keratocyte damage; after 6 months a repopulation by proliferating cells, a distribution of CD34-positive keratocytes as in control and an increase in collagen fibre diameter were observed. These modifications are the morphological correlate of the process leading to an increase in biomechanical stability.

  16. Development of a rabbit corneal equivalent using an acellular corneal matrix of a porcine substrate.

    Science.gov (United States)

    Xu, Yong-Gen; Xu, Yong-Sheng; Huang, Chen; Feng, Yun; Li, Ying; Wang, Wei

    2008-01-01

    The tissue equivalent that mimics the structure and function of normal tissue is a major bioengineering challenge. Tissue engineered replacement of diseased or damaged tissue has become a reality for some types of tissue such as skin and cartilage. The tissue engineered corneal epithelium, stroma, and endothelium scaffold are promising concepts in overcoming the current limitations of a cornea replacement with an allograft. The acellular corneal matrix from porcine (ACMP) was examined as a potential corneal cell sheet frame. The physical and mechanical properties of strength, expansion, transparency, and water content of the ACMP were measured. The major antigens of the cell components were completely removed with series of extraction methods, the major antigens of the cell components were identified by hematoxylin and eosin (HE), immunofluorescence staining, and scanning electron microscopy. The structural properties were investigated by HE stain and scanning electron microscopy. The three types of rabbit corneal cells were cultured in vitro, and characteristics were investigated by colony formation efficiency (CFE), BrdU staining, immunofluorescence staining, and western blot assay of keratin 3 (K3), vimentin, and aquaporin A. The biocompatibility of the ACMP was investigated for one month using rabbit corneal stroma and three types of cultured corneal cells both in vivo and in vitro. The three types of cultured rabbit corneal cells were seeded onto ACMP of each side at a cell density of 5.0 x 10(3) cells/mm(2). The optical and mechanical properties of the ACMP were similar to the normal porcine cornea. The collagen fiber interconnected to the network, formed regular collagen bundles of the ACMP, and was parallel to the corneal surface. The ACMP was transferred to the rabbit cornea stroma, which showed an intact epithelium and keratocytes in the implant region. There were no inflamed cells or new vessel invasion one month after transplantation. The three types of

  17. Corneal biomechanical properties and intraocular pressure in high myopic anisometropia.

    Science.gov (United States)

    Xu, Suzhong; Xu, Aiqin; Tao, Aizhu; Wang, Jianhua; Fan, Fan; Lu, Fan

    2010-07-01

    To investigate corneal biomechanical properties and intraocular pressure (IOP) in patients with high myopic anisometropia. Patients with high myopic anisometropia (n = 23) and emmetropic subjects (n = 55) were enrolled. Corneal hysteresis (CH), Goldmann-correlated intraocular pressure (IOPg), corneal resistance factor, and corneal-compensated IOP (IOPcc) were measured with Ocular Response Analyzer. Central corneal thickness was measured by optical coherence tomography. Zeiss IOL-Master determined the values of corneal refractive power and ocular axial length. Significant differences were presented in CH, IOPg, and IOPcc among the high myopic, contralateral, and normal eyes (analysis of variance, Panisometropia. High myopic eyes showed decreased CH, but not corneal resistance factor, which indicates that some aspects of corneal biomechanical properties may be altered in high myopic eye of anisometropia. It is also suggested that anisometropic eyes with different refractive errors do not share the same biomechanical properties, which may impact IOP measurement.

  18. Changes on the corneal thickness and curvature after orthokeratology

    Science.gov (United States)

    Mitsui, Iwane; Yamada, Yoshiya

    2004-07-01

    To evaluate the corneal thickness and curvature changes after Orthokeratology contact lens wear, using the ORBSCAN II corneal topography system, corneal thickness and corneal curvature were measured on one hundred and twenty eyes of sixty patients before and after wearing the custom rigid gas permeable contact lenses for Orthokeratology. The contact lenses were specially designed for each eye. The subjects wore the orthokeratology lenses for approximately Four hours with their eyes closed. The corneal thickness of the subjects was increased on fifty-five eyes at not only the peripheral zone but also the center of the cornea. The average increase of central and peripheral corneal thickness was 18 micrometer and 22micrometer, respectively. The mean anterior curvature of corneal surface changed 1.25D. The mean posterior curvature of corneal endothelium side changed 0.75D.

  19. Corneal graft dellen in a patient implanted with a Boston keratoprosthesis type 1.

    Science.gov (United States)

    Scotto, Riccardo; Vagge, Aldo; Traverso, Carlo E

    2017-02-01

    The purpose of this study was to report a case of corneal dellen in a patient implanted with a Boston type 1 keratoprosthesis (KPro), which rapidly appeared after the loss of the large-diameter soft contact lens. This study is an observational case report of a 56-year-old man who underwent KPro implantation in his right eye in November 2010. In March 2014 during a follow-up visit, two areas of corneal dellen were observed. The patient had lost his bandage contact lens. With the application of a new soft contact lens, the thinned areas recovered completely within 5 days. After keratoprosthesis implantation, it is necessary to maintain uninterrupted wear of a bandage contact lens as it allows for adequate ocular surface hydration and prevents consequent complications. This case report highlights the need to provide proper instructions to such patients, in order to minimize the risk.

  20. Effects of Topical 1% Sodium Hyaluronate and Hydroxypropyl Methylcellulose in Treatment of Corneal Epithelial Defects.

    Science.gov (United States)

    Shahraki, Kourosh; Hosseini, Seyed-Rafi; Amini Fard, Atefeh; Shademan, Hashem; Shahraki, Kianoush; Salari, Amir Masood; Amini Fard, Mohammad-Naeim

    2016-01-01

    We aimed to compare the therapeutic effects of topical 1% sodium hyaluronate (Healon) or hydroxypropyl methylcellulose (HPMC) for the treatment of alkali-induced epithelial corneal defects. An alkali burn was produced in 30 corneas of 30 New Zealand White rabbits, using a 7.5-mm-diameter trephine. The rabbits were randomly divided into three groups. Four times a day, one group was treated with 1% sodium hyaluronate, one with HPMC, and one (the control group) with physiologic saline. During the treatment period, the size of the epithelial defect was observed every day, up to day 17, using a slit-lamp biomicroscope (with fluorescein). Sodium hyaluronate significantly accelerated the wound healing process compared with saline and increased the healing rate to an even greater extent compared with HPMC. Sodium hyaluronate, but not HPMC, is an effective wound-healing adjuvant for alkali-induced corneal epithelial defects.

  1. Analysis of low-energy and high-frequency femtosecond laser for the construction of deep anterior donor corneal lamellae

    Directory of Open Access Journals (Sweden)

    Gustavo Victor

    2014-04-01

    Full Text Available Purpose: To evaluate the efficacy and reliability of a low-energy femtosecond laser with a high repetition rate for construction of deep anterior donor corneal lamellae. Methods: This was a prospective laboratory investigation. Twenty-five human corneal buttons were femtosecond laser cut to create thick anterior lamellae (diameter, 10mm; thickness, 500µm. The laser cuts were made using an LDV® femtosecond laser in a Ziemer® anterior chamber. To obtain a better edge, the lamellae were trephined with an 8mm trephine (Katena®. The central corneal thickness and the anterior lamellae were measured using a Mitutoyo® thickness gauge with an accuracy of 0.001mm. Results: The central thickness of the 25 corneas ranged from 500 to 705µm (mean, 584 ± 51µm. The thickness of the anterior lamellae ranged from 420 to 480µm (mean, 455 ± 12.7µm. The anterior lamellae diameters were 7.90 ± 0.1mm, and all laser cuts were round. The lamellar interfaces appeared regular by surgical microscopy. There were no cases of inter-lamellar adhesion. Conclusion: The LDV® femtosecond laser appears to be a safe and reliable instrument for cutting deep anterior lamellae from donor corneoscleral buttons. Minimal variation in donor lamellar depth with the laser will be useful for creating donor corneal tissue for deeper anterior lamellar keratoplasty or endothelial keratoplasty surgery or both from a single donor cornea.

  2. [Use of the confocal laser scanning method for determining corneal topography and corneal tissue effects in refractive corneal surgery].

    Science.gov (United States)

    Koop, N; Brinkmann, R; Schirner, G

    1996-06-01

    Refraction of the cornea head been generally measured with ophthalmometers or computer disk keratometers. We therefore used a confocal laser scanning system for measurement of the corneal topography. Enucleated tonicized pig eyes were measured before and after laser thermokeratoplasty (LTK). The topographical data were used to determine refraction and refractive change; the data were stored digitally. The single images and their differences were displayed on a PC. Unlike conventional ophthalmometry, confocal laser scanning can demonstrate the topographical shape, showing the overall topography of the cornea and local corneal effects, e.g., coagulation, mechanical lesions or high-energy laser effects. Topographical laser scanning has proven to be a generally useful method of determining refraction and surface alterations in corneal refractive surgery.

  3. Corneal reconstruction by stem cells and bioengineering

    Directory of Open Access Journals (Sweden)

    Arjamaa O

    2012-09-01

    Full Text Available Olli ArjamaaDepartment of Biology, University of Turku, Turku, FinlandAbstract: Almost 300 million people are visually impaired worldwide due to various eye diseases such as cataracts, glaucoma, age-related macular degeneration, diabetic retinopathy, and corneal diseases. Notably, ten million people are blind because of severe ocular surface diseases and the majority of cases occur in developing countries. Blinding ocular surface diseases have, however, become treatable by grafting of surface layers, or by full-thickness transplantation of the cornea. As the demand for human corneal tissue for surface reconstruction and transplantation far exceeds the supply, methods are being developed to supplement tissue donation. Xenotransplantation of the cornea or cells from genetically modified pigs may become one of the solutions. Transplantation of limbal stem cells within tissue biopsies, to restore the transparency of the cornea is another remarkable method, which has shown its potential in several clinical studies. The combination of stem cell technology and engineering of biocompatible tissue equivalent, still at preclinical stage, has shown us how synthetic corneal tissue is able to guide cultured corneal stromal stem cells of human origin, to become native-like stroma, the most important layer of the cornea. These findings give hope for a large-quantity production of biomaterial for corneal reconstruction. As such, clinical ophthalmologists should become more familiar with the methods of laboratory science.Keywords: eye, grafting, keratoplasty, xenotransplantation, cell reservoir, biocompatible tissue equivalent

  4. Corneal collagen cross-linking outcomes: review.

    Science.gov (United States)

    Jankov Ii, Mirko R; Jovanovic, Vesna; Delevic, Sladjana; Coskunseven, Efekan

    2011-02-11

    Keratoconus is a condition characterized by biomechanical instability of the cornea, presenting in a progressive, asymmetric and bilateral way. Corneal collagen cross-linking with riboflavin and UVA (CXL) is a new technique of corneal tissue strengthening that combines the use of riboflavin as a photo sensitizer and UVA irradiation. The studies showed that CXL was effective in halting the progression of keratoconus over a period of up to four years. The published studies also revealed a reduction of max K readings by more than 2 D, while the postoperative SEQ was reduced by an average of more than 1 D, and refractive cylinder decreased by about 1 D. No eyes lost any line of BCDVA. Moreover, there was no significant decrease in endothelial cell density. It was also found that CXL treatment was effective with reducing corneal and total wavefront aberrations. Corneal cross-linking has also led to an arrest and/or even a partial reversal of keratectasia in the treatment of iatrogenic ectasia after excimer laser ablation. A primary intervention such as CXL should be considered to potentially increase the biomechanical stability of the corneal tissue and postpone the need of lamellar or penetrating keratoplasty.

  5. Trends in corneal transplantation: indications and techniques.

    Science.gov (United States)

    Ple-Plakon, Patricia A; Shtein, Roni M

    2014-07-01

    To describe trends in corneal transplantation surgery, including indications for surgery, evolution of lamellar keratoplasty, current surgical techniques, and future directions. Over the past decade, anterior and posterior lamellar keratoplasty have begun to supplant penetrating keratoplasty. Surgical techniques continue to change and improve outcomes. In recent years, Descemet membrane endothelial keratoplasty (DMEK) has gained interest as it eliminates the corneal stromal interface, which may limit visual acuity after Descemet stripping automated endothelial keratoplasty. Despite the promising results with improved visual acuity and decreased rejection, the technical challenges associated with DMEK have limited widespread acceptance. With technical refinements and more eye banks providing precut tissue for both Descemet stripping automated endothelial keratoplasty and DMEK, it is likely both procedures will continue to increase over time. Corneal transplantation has evolved rapidly over the past decade, from full-thickness penetrating keratoplasty towards lamellar keratoplasty to only remove and replace damaged layers of the cornea. Achieving minimal induced astigmatism with excellent visual acuity remains a challenge in corneal transplantation. Further refinements in surgical technique may help improve technical challenges and visual outcomes. In this article, we review changing trends in corneal transplantation and highlight developing medical treatments that may be available in the future.

  6. Corneal transplantation: A new view of life.

    Science.gov (United States)

    Amiri, Fardin; Ghiyasvandian, Shahrzad; Navab, Elham; Zakerimoghadam, Masoumeh

    2017-04-01

    The consequences of a corneal transplant are evaluated and classified by care providers, but understanding and interpretation of the results varies between patients, and creates different views for them and influences their lives in different ways while these influences are largely unknown. This study aimed to explore understanding of new life in patients after corneal transplantation. This qualitative study was conducted using a hermeneutic phenomenological approach in Tehran in 2016. Twelve corneal transplant recipients (7 men, 5 women) who were chosen purposefully from penetrating corneal transplant recipients, participated in this study. Semi-structured interviews were used to collect data. The content of the interviews was transcribed and analyzed using Van Manen's methodology. Data analysis led to the emergence of several main themes, among which "having a new sense" and "fear and hope" were two of the most important themes. It can be inferred from the overall participants' experiences that corneal transplant has brought about a new look at life for patients. However, transplant-related issues are endless and continuous, and a sense of fear and hope has always surrounded them.

  7. MicroRNA-184 Regulates Corneal Lymphangiogenesis.

    Science.gov (United States)

    Grimaldo, Sammy; Yuen, Don; Theis, Jaci; Ng, Melissa; Ecoiffier, Tatiana; Chen, Lu

    2015-11-01

    MicroRNAs are a class of small noncoding RNAs that negatively regulate gene expression by binding to complimentary sequences of target messenger RNA. Their roles in corneal lymphangiogenesis are largely unknown. This study was to investigate the specific role of microRNA-184 (mir-184) in corneal lymphangiogenesis (LG) in vivo and lymphatic endothelial cells (LECs) in vitro. Standard murine suture placement model was used to study the expressional change of mir-184 in corneal inflammatory LG and the effect of synthetic mir-184 mimic on this process. Additionally, a human LEC culture system was used to assess the effect of mir-184 overexpression on cell functions in vitro. Expression of mir-184 was significantly downregulated in corneal LG and, accordingly, its synthetic mimic suppressed corneal lymphatic growth in vivo. Furthermore, mir-184 overexpression in LECs inhibited their functions of adhesion, migration, and tube formation in vitro. These novel findings indicate that mir-184 is involved critically in LG and potentially could be used as an inhibitor of the process. Further investigation holds the promise for divulging new therapies for LG disorders, which occur inside and outside the eye.

  8. In-vitro corneal transparency measuring system

    Science.gov (United States)

    Ventura, Liliane; da Costa Vieira, Marcelo A.; Isaac, Flavio; Chiaradia, Caio; Faria de Sousa, Sidney J.

    2001-06-01

    A system for measuring the average corneal transparency of preserved corneas has been developed in order to provide a more accurate and standard report of the corneal tissue. The donated cornea transparency is one of the features to be analyzed previously to its indication for the transplant. The small portable system consists of two main parts: the optical and the electronic parts. The optical system consists of a white light, lenses and pin-holes that collimate white light beams that illuminates the cornea in its preservative medium. The light that passes through the cornea is detected by a resistive detector and the average corneal transparency is shown in a display. In order to obtain just the tissue transparency, the electronic circuit was built in a way that there is a baseline input of the preservative medium, previous to the measurement of the corneal transparency. Manipulating the system consists of three steps: (1) Adjusting the zero percentage in the absence of light (at this time the detectors in the dark); (2) Placing the preservative medium in the system and adjusting the 100% value (this is the baseline input); (3) Preserving the cornea and placing it in the system. The system provides the tissue transparency. The system is connected to an endothelium evaluation system for Slit Lamp, that we have developed, and statistics about the relationship of the corneal transparency and density of the endothelial cells will be provided in the next years. The system is being used in a public Eye Bank in Brasil.

  9. Riboflavin for corneal cross-linking.

    Science.gov (United States)

    O'Brart, D P S

    2016-06-01

    Corneal collagen cross-linking (CXL) with riboflavin and ultraviolet A (UVA) radiation is the first therapeutic modality that appears to arrest the progression of keratoconus and other corneal ectasias. Riboflavin is central to the process, acting as a photosensitizer for the production of oxygen singlets and riboflavin triplets. These free radicals drive the CXL process within the proteins of the corneal stroma, altering its biomechanical properties. Riboflavin also absorbs the majority of the UVA radiation, which is potentially cytotoxic and mutagenic, within the anterior stroma, preventing damage to internal ocular structures, such as the corneal endothelium, lens and retina. Clinical studies report cessation of ectatic progression in over 90% of cases and the majority document significant improvements in visual, keratometric and topographic parameters. Clinical follow-up is limited to 5-10 years, but suggests sustained stability and enhancement in corneal shape. Sight-threatening complications are rare. The optimal stromal riboflavin dosage for CXL is as yet undetermined. Copyright 2016 Prous Science, S.A.U. or its licensors. All rights reserved.

  10. Primary central corneal hemangiosarcoma in a dog.

    Science.gov (United States)

    Haeussler, David J; Rodríguez, Laura Muñoz; Wilkie, David A; Premanandan, Chris

    2011-03-01

    To report a case of primary central corneal hemangiosarcoma in the dog. An 11-year-old, neutered, female, German shepherd mixed breed dog was referred to the Hospital Veterinario Sierra de Madrid (Spain) for evaluation of an enlarging corneal mass of the left eye (OS). The dog was predominantly housed outdoors and was diagnosed with a history of chronic superficial keratitis of both eyes (OU) by the referring veterinarian. The corneal mass was resected by routine superficial keratectomy and submitted for histopathology and Factor VIII immunohistochemical staining. The mass was diagnosed as a corneal hemangiosarcoma with complete excision. Postoperatively, the keratectomy site healed without complication and there was no evidence of recurrence three and a half months postoperatively. Complete systemic evaluation, including abdominal ultrasound and CT scan of the head and thorax, indicated no other detectable neoplasia in the dog. Outdoor housing and ultraviolet exposure, breed, and chronic superficial keratitis were all suspected as contributing factors to the development of a primary corneal hemangiosarcoma. Surgical removal and postoperative treatment for chronic superficial keratitis provided effective therapy. © 2011 American College of Veterinary Ophthalmologists.

  11. Corneal Biomechanics in Ectatic Diseases: Refractive Surgery Implications

    OpenAIRE

    Ambr?sio, Jr, Renato; Correia, Fernando Faria; Lopes,Bernardo; Salom?o, Marcella Q.; Luz,Allan; Daniel G Dawson; Elsheikh, Ahmed; Vinciguerra, Riccardo; Vinciguerra, Paolo; Roberts, Cynthia J.

    2017-01-01

    Background: Ectasia development occurs due to a chronic corneal biomechanical decompensation or weakness, resulting in stromal thinning and corneal protrusion. This leads to corneal steepening, increase in astigmatism, and irregularity. In corneal refractive surgery, the detection of mild forms of ectasia pre-operatively is essential to avoid post-operative progressive ectasia, which also depends on the impact of the procedure on the cornea. Method: The advent of 3D tomography is proven as a ...

  12. The value of corneal transplantation in reducing blindness.

    Science.gov (United States)

    Garg, P; Krishna, P V; Stratis, A K; Gopinathan, U

    2005-10-01

    To analyse the role of keratoplasty in reducing world blindness due to corneal diseases. Review of published literature. We collected and analysed articles published in the English language literature related to the prevalence and causes of blindness in different parts of the world, causes of corneal blindness, and outcome of corneal transplantation for various corneal diseases. A total of 80% of the world's blind live in developing countries. Retinal diseases are the most important causes of blindness (40-54%) in established economy nations while cataract (44-60%) and corneal diseases (8-25%) are the most common causes of blindness in countries with less developed economies. Keratitis during childhood, trauma, and keratitis during adulthood resulting in a vascularized corneal scar and adherent leucoma are the most frequent causes of corneal blindness in developing countries. Corneal diseases are responsible for 20% of childhood blindness. Nearly 80% of all corneal blindness is avoidable. The outcome of keratoplasty for vascularized corneal scar and adherent leucoma is unsatisfactory, necessitating repeat surgery in a high proportion of these cases. Other barriers for keratoplasty in these nations are suboptimal eye banking, lack of trained human resources, and infrastructure. Since the developing world carries most of the load of corneal blindness and the major causes of corneal blindness are corneal scar and active keratitis, development of corneal transplantation services need a comprehensive approach encompassing medical standards in eye banking, training of cornea specialists and eye banking personnel and exposure of ophthalmologists to care of corneal transplants for better follow-up care. However, concerted efforts should be made to develop and implement prevention strategies since most corneal blindness is preventable.

  13. Corneal hysteresis, corneal resistance factor, and intraocular pressure measurements in eyes implanted with a small aperture corneal inlay.

    Science.gov (United States)

    Agca, Alper; Demirok, Ahmet; Celik, Haci Ugur; van de Pol, Corina; Cankaya, Kadir Ilker; Celik, Nimet Burcu; Yasa, Dilek; Yilmaz, Ihsan; Yilmaz, Omer Faruk

    2014-12-01

    To compare the postoperative corneal hysteresis (CH) and corneal resistance factor (CRF) of eyes implanted with a small aperture corneal inlay versus fellow eyes. Medical records of patients who underwent small aperture corneal inlay (KAMRA; AcuFocus, Inc., Irvine, CA) implantation were retrospectively reviewed. There were two groups: the implanted and non-implanted. Main outcome measures were CH, CRF, Goldmann-correlated intraocular pressure (IOPg), corneal-compensated IOP (IOPcc), and Goldmann applanation tonometry measurements performed preoperatively and at postoperative week 1 and months 1, 3, and 6. The study included 68 eyes of 34 patients. CH was higher in the implanted group when compared with the non-implanted group at postoperative week 1 (12.2 ± 3.1 vs 10.9 ± 1.7 mm Hg; P = .007) and month 1 (12.3 ± 2.5 vs 10.9 ± 1.8 mm Hg; P = .001). CRF was higher in the implanted group when compared with the non-implanted group at postoperative week 1 (11.9 ± 2.9 vs 10.7 ± 1.6 mm Hg; P = .003) and month 1 (12.5 ± 2.5 vs 10.4 ± 1.8 mm Hg; P .05). At the 3-month postoperative visit, all parameters had returned to baseline and there was no change at the 6-month visit. Implantation of the KAMRA corneal inlay does not induce a permanent change in CH or CRF. A transient increase in both was seen in the early postoperative period. Copyright 2014, SLACK Incorporated.

  14. Corneal Stroma Regeneration with Acellular Corneal Stroma Sheets and Keratocytes in a Rabbit Model.

    Science.gov (United States)

    Ma, Xiao Yun; Zhang, Yun; Zhu, Dan; Lu, Yang; Zhou, Guangdong; Liu, Wei; Cao, Yilin; Zhang, Wen Jie

    2015-01-01

    Acellular corneal stroma matrix has been used for corneal stroma engineering. However, because of its compact tissue structure, regrowth of keratocytes into the scaffold is difficult. Previously, we developed a sandwich model for cartilage engineering using acellular cartilage sheets. In the present study, we tested this model for corneal stroma regeneration using acellular porcine corneal stroma (APCS) sheets and keratocytes. Porcine corneas were decellularized by NaCl treatment, and the APCS was cut into 20-μm-thick sheets. A rabbit corneal stroma defect model was created by lamellar keratoplasty and repaired by transplantation of five pieces of APCS sheets with keratocytes. Six months after transplantation, transparent corneas were present in the experimental group, which were confirmed by anterior segment optical coherence tomography examination and transmittance examination. The biomechanical properties in the experimental group were similar to those of normal cornea. Histological analyses showed an even distribution of keratocytes and well-oriented matrix in the stroma layer in the experimental group. Together, these results demonstrated that the sandwich model using acellular corneal stroma sheets and keratocytes could be potentially useful for corneal stroma regeneration.

  15. Value of recombinant human epidermal growth factor in corneal wound repair after corneal foreign body elimination

    Directory of Open Access Journals (Sweden)

    Hong-Jie Han

    2013-11-01

    Full Text Available AIM: To investigate the repair efficacy of recombinant human epidermal growth factor on corneal epithelium after corneal foreign body eliminating operation. METHODS: There were 102 patients with corneal foreign body(188 affected eyeschosen for the study. All patients were divided into treatment group and control group according to the random number table. Both groups received corneal foreign body elimination by slit lamp. Postoperatively, the treatment group was given eye drops containing epidermal growth factor(JinYinShucombined with tobramycin while the control group was only administrated with tobramycin. Treatment effects were compared 3d after treatment. RESULTS: Three days after treatment, the cure rate in the treatment group(93.7%, was significantly higher than that in the control group(76.6%(PPCONCLUSION: The recombinant human epidermal growth factor is capable of integrating with corneal epithelial cells and endothelial cell receptor, shortening healing time of corneal epithelial wound, thus making it an effective treatment of traumatic corneal epithelial defect.

  16. Randomized Trial Comparing Amniotic Membrane Transplantation with Lamellar Corneal Graft for the Treatment of Corneal Thinning.

    Science.gov (United States)

    de Farias, Charles C; Allemann, Norma; Gomes, José Á P

    2016-04-01

    There are few studies comparing different surgical procedures for the treatment of corneal thinning. Lamellar corneal transplantation (LCT) has been reported to be efficient, but its results can be jeopardized by allograft rejection, opacification, or high astigmatism. Amniotic membrane transplantation (AMT) has been considered a good alternative, but it is not as resistant as LCT and the tissue can be reabsorbed after surgery. A prospective, randomized, interventional, and comparative study of consecutive patients with corneal thinning over 6 months was performed. Ophthalmological examination was performed before transplant surgery and then repeated 1, 7, 15, 30, 90, and 180 days after surgery and ultrasound biomicroscopy was performed before and then 30, 90, and 180 days after surgery to assess corneal thinning. Herpes simplex infection was the main cause of corneal thinning (9 eyes), followed by surgery (cataract, glaucoma, 5 cases), rheumatoid arthritis (1), chemical burn (1), perforating trauma (1), previous band keratopathy treatment (1), and Stevens-Johnson syndrome (1). Although all patients showed significant increase in final thickness in the area of thinning, it was higher in those submitted to LCT at 180 days postoperatively. Regardless of the surgical technique, all patients showed epithelialization. Patients undergoing AMT showed an 89% decrease in neovascularization. Final corrected distance visual acuity was better in patients submitted to AMT. LCT proved to be the best option for treating corneal thinning. AMT represents an alternative that allows good visual recovery but does not restore corneal thickness as efficiently as LCT.

  17. [Evaluation of corneal biomechanical properties in glaucoma and control patients by dynamic Scheimpflug corneal imaging technology].

    Science.gov (United States)

    Coste, V; Schweitzer, C; Paya, C; Touboul, D; Korobelnik, J-F

    2015-06-01

    To compare corneal biomechanical properties measured with Corvis Scheimpflug technology (Corvis ST) between a group of patients with chronic open-angle glaucoma and a group of control patients. Prospective observational case-control study. This study enrolled 56 right eyes of 56 patients (G1 [chronic open-angle glaucoma] n=37/G2 [control] n=19). Each patient underwent measurement of corneal biomechanical properties by dynamic Scheimpflug (Corvis ST) camera and the Ocular Response Analyser (ORA), then a measurement of intraocular pressure (IOP) by Goldmann applanation tonometry (GAT) and measurement of central corneal thickness (CCT) by optical coherence tomography during the same visit, by a single clinician. The parameters determined by Corvis ST are: Corvis IOP (IOP Corvis ST), the corneal deformation amplitude (CDA), corneal velocity, the time at highest concavity (TIME CONCAV), the lengths of applanation and their corresponding applanation time. Those studied by ORA are: compensated IOP (IOPcc), non-compensated IOL (IOPg), corneal hysteresis (CH) and corneal resistance factor (CRF). IOP measured on all patients by Corvis ST was positively correlated to GAT (Spearman r=0.569, Pcorneal biomechanical properties between glaucoma and control patients. The cornea of glaucoma patients appears less deformable. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  18. Relationship Between Corneal Hysteresis and Corneal Resistance Factor with Other Ocular Parameters.

    Science.gov (United States)

    Rosa, Nicola; Lanza, Michele; De Bernardo, Maddalena; Signoriello, Giuseppe; Chiodini, Paolo

    2015-01-01

    To evaluate the relationship between corneal hysteresis (CH) and corneal resistance factor (CRF) with age, central corneal thickness (CCT), corneal curvature (KM), corneal volume (CV), and refractive error in naïve eyes. 105 healthy subjects (58 male and 47 female) were included in this study. The ages ranged from 19 to 82 years (mean 43.1 ± 15.4 years) and refraction between -11 D and +6 D (mean -0.79 ± 2.95 D). CH and CRF obtained with the Ocular Response Analyzer (ORA) were correlated with age, refractive error, Goldmann Applanation Tonometry (GAT), and with CCT, KM, CV obtained with the Pentacam, and with Corneal-Compensated Intraocular Pressure (IOPcc) and Goldmann-correlated intraocular pressure measurement (IOPg) obtained with ORA. A multivariable mixed effect model was used to evaluate associations among these parameters. CH ranged from 6.9 to 14.6 mmHg (mean 10.26 ± 1.49 mmHg); CRF ranged from 5.8 to 17 mmHg (mean 10.38 ± 1.64 mmHg). Multivariate analysis showed a statistically significant correlation between CH with CCT (p corneal shape and thickness, and show a decrease of CH with age.

  19. Clinical significance of central corneal thickness and comparison of central corneal thickness

    Directory of Open Access Journals (Sweden)

    Özgür Çakıcı

    2014-03-01

    Full Text Available Significance of central corneal thickness has been increasing in ophthalmology practice. It is an important clinical evaluation tool especially prior to refractive surgery and in diagnosis of glaucoma and keratoconus. Refractive surgery is planned according to preoperative central corneal thickness measurements. Besides, in order to determine actual intraocular pressure, central corneal thickness is measured and corrected eye pressure is obtained. Today, devices used in measurement of central corneal thickness do the measurement according to two principles. First and relatively older method is ultrasonic method. Optic method is the second and more recent method. In daily practice, the most commonly used clinical method in measurement of central corneal thickness is ultrasound pachymeter. However, this measurement technique requires contact between cornea and probe and gives thinner measurement results compared to the methods that use optic principle. Recently, several technologic methods based on optics have been put in use; they provide advantages of non-contact technique and objective determination of central corneal thickness. Of these methods, most commonly used include Specular Microscopy, Optical coherence tomography, Laser Doppler Interferometry, Optical low coherence reflectometry pachymetry, Optic based topographic mapping (also called screening section pachymetry and Pentacam. In this article, it was aimed to evaluate importance of central corneal thickness in clinical use and compare measurement methods. J Clin Exp Invest 2014; 5 (1: 153-158

  20. Corneal Stroma Regeneration with Acellular Corneal Stroma Sheets and Keratocytes in a Rabbit Model.

    Directory of Open Access Journals (Sweden)

    Xiao Yun Ma

    Full Text Available Acellular corneal stroma matrix has been used for corneal stroma engineering. However, because of its compact tissue structure, regrowth of keratocytes into the scaffold is difficult. Previously, we developed a sandwich model for cartilage engineering using acellular cartilage sheets. In the present study, we tested this model for corneal stroma regeneration using acellular porcine corneal stroma (APCS sheets and keratocytes. Porcine corneas were decellularized by NaCl treatment, and the APCS was cut into 20-μm-thick sheets. A rabbit corneal stroma defect model was created by lamellar keratoplasty and repaired by transplantation of five pieces of APCS sheets with keratocytes. Six months after transplantation, transparent corneas were present in the experimental group, which were confirmed by anterior segment optical coherence tomography examination and transmittance examination. The biomechanical properties in the experimental group were similar to those of normal cornea. Histological analyses showed an even distribution of keratocytes and well-oriented matrix in the stroma layer in the experimental group. Together, these results demonstrated that the sandwich model using acellular corneal stroma sheets and keratocytes could be potentially useful for corneal stroma regeneration.

  1. Corneal Diseases in Children in The Gambia | Onabolu | Nigerian ...

    African Journals Online (AJOL)

    trauma in 23 (32.4%) vernal kerato-conjunctivitis in 16 (22.54%), congenital eye diseases in 12 (16.9%), corneal infections in 12 (16.9%), corneal scarring from unknown causes in 5 (7.04%) and corneal dystrophy/degenerations in 3 patients. Ten patients (14%) became bilaterally blind while 22 patients (31%) suffered ...

  2. [Evaluation of corneal endothelium morphology in diabetic patients].

    Science.gov (United States)

    Wesołek-Czernik, Agata; Bartela, Joanna; Zamojska, Ewa; Omulecki, Wojciech

    2007-01-01

    To evaluate the influence of diabetes mellitus and type of hipoglicemic therapy on corneal endothelium cell morphology. In 68 diabetic patients' eyes with non proliferative diabetic retinopathy (29 males and 39 females), corneal endothelium was studied. Patients age was between 50 and 82 years (mean 63.28). As age-matched control group we analyzed 58 eyes of non diabetic patients. Corneal endothelium density, percentage of corneal endothelium hexagonal cells, average size of corneal endothelium cells and corneal thickness were imaged by non-contact specular microscope TOPCON SP-2000P. The mean corneal endothelium cell density was: 2467 cells/mm2 in diabetic patients, and 2573 cells/mm2 in control group. The mean percentage of corneal endothelium hexagonal cells was: 55.3% in diabetic patients treated with insulin and 52.9% in diabetic patients treated with oral antidiabetic drugs, and 54.4% in the control group. The mean size of corneal endothelium cells was: 414.6 microm2 in diabetic patients, and 395.9 microm2 in the control group. The mean corneal thickness was: 0.556 mm in diabetic patients and 0.545 mm in the control group. Corneal endothelium was thicker in diabetic patients than in non diabetic patients. The duration of diabetes mellitus had no influence on corneal endothelium cell morphology. Diabetic patients treated with oral antidiabetic drugs had larger percentage of hexagonal cells than those treated with insulin.

  3. Pattern of corneal opacity in Ibadan, Nigeria | Ashaye | Annals of ...

    African Journals Online (AJOL)

    Background: The prevalence and causes of corneal blindness vary from one region of the world to another. There is even variation within the developing countries of Africa. Method: A retrospective review of 675 patients with corneal scarring out of the 3,753 new patients corneal scarring in patients attending the eye clinic of ...

  4. Mechanical methods in refractive corneal surgery.

    Science.gov (United States)

    Hoffmann, F; Kruse, H; Schüler, A

    1993-08-01

    Keratorefractive surgery has developed rapidly over the past decade. For patients with aphakia, however, posterior chamber lenses are safer and more predictable than refractive corneal surgery; myopia is the greatest challenge to this type of surgery. No technique as yet has an accuracy that is adequate for the general treatment of myopia. Keratotomy is the most common procedure currently performed for the correction of mild myopia and astigmatism. Results are less accurate and less stable with myopic than with aphakic epikeratoplasty. Although it is technically more difficult, keratomileusis seems to be more predictable than epikeratophakia. Nonfreeze lamellar corneal surgery accelerates wound healing. Synthetic lenses and ring-shaped implants are also being developed to modify corneal refraction. Current research is directed toward laser stromal keratomileusis on discs that are removed from the cornea using a microkeratome.

  5. Cataract phacoemulsification and corneal endothelial cell damage

    Directory of Open Access Journals (Sweden)

    Ni Zhu

    2013-07-01

    Full Text Available Phacoemulsification with small incision, reduced number of inflammation cells, and better postoperative recovery has been recognized as the world's most popular option for cataract surgery. Modern cataract surgery is developing gradually from sight rehabilitating to refractive surgery with better vision acuity. Being the most important part of the eye refractive system, maintenance of the cornea's transparency relies heavily upon the healthy endothelial cells. It is well known that there will be endothelial cell loss after phacoemulsification and the damage of the endothelial cells may lead to corneal swellings and opacity, or even the corneal descompensation, which often severely influenced the postoperative vision recovery. This is a review of phacoemulsification and the risk factors of corneal endothelial damage pre-and postoperation.

  6. XENOTRANSPLANTATION – THE FUTURE OF CORNEAL TRANSPLANTATION?

    Science.gov (United States)

    Hara, Hidetaka; Cooper, David K.C.

    2010-01-01

    Although corneal transplantation is readily available in the USA and certain other regions of the developed world, the need for human donor corneas worldwide far exceeds supply. There is currently renewed interest in the possibility of using corneas from other species, especially pigs, for transplantation into humans (xenotransplantation). The biomechanical properties of human and pig corneas are similar. Studies in animal models of corneal xenotransplantation have documented both humoral and cellular immune responses that play roles in xenograft rejection. The results obtained from the Tx of corneas from wild-type (i.e., genetically-unmodified) pigs into nonhuman primates have been surprisingly good and encouraging. Recent progress in the genetic manipulation of pigs has led to the prospect that the remaining immunological barriers will be overcome. There is every reason for optimism that corneal xenoTx will become a clinical reality within the next few years. PMID:21099407

  7. Applications of biomaterials in corneal wound healing.

    Science.gov (United States)

    Tsai, I-Lun; Hsu, Chih-Chien; Hung, Kuo-Hsuan; Chang, Chi-Wen; Cheng, Yung-Hsin

    2015-04-01

    Disease affecting the cornea is a common cause of blindness worldwide. To date, the amniotic membrane (AM) is the most widely used clinical method for cornea regeneration. However, donor-dependent differences in the AM may result in variable clinical outcomes. To overcome this issue, biomaterials are currently under investigation for corneal regeneration in vitro and in vivo. In this article, we highlight the recent advances in hydrogels, bioengineered prosthetic devices, contact lenses, and drug delivery systems for corneal regeneration. In clinical studies, the therapeutic effects of biomaterials, including fibrin and collagen-based hydrogels and silicone contact lenses, have been demonstrated in damaged cornea. The combination of cells and biomaterials may provide potential treatment in corneal wound healing in the future. Copyright © 2014. Published by Elsevier Taiwan.

  8. Applications of biomaterials in corneal wound healing

    Directory of Open Access Journals (Sweden)

    I-Lun Tsai

    2015-04-01

    Full Text Available Disease affecting the cornea is a common cause of blindness worldwide. To date, the amniotic membrane (AM is the most widely used clinical method for cornea regeneration. However, donor-dependent differences in the AM may result in variable clinical outcomes. To overcome this issue, biomaterials are currently under investigation for corneal regeneration in vitro and in vivo. In this article, we highlight the recent advances in hydrogels, bioengineered prosthetic devices, contact lenses, and drug delivery systems for corneal regeneration. In clinical studies, the therapeutic effects of biomaterials, including fibrin and collagen-based hydrogels and silicone contact lenses, have been demonstrated in damaged cornea. The combination of cells and biomaterials may provide potential treatment in corneal wound healing in the future.

  9. Corneal nerve microstructure in Parkinson's disease.

    Science.gov (United States)

    Misra, Stuti L; Kersten, Hannah M; Roxburgh, Richard H; Danesh-Meyer, Helen V; McGhee, Charles N J

    2017-05-01

    Ocular surface changes and blink abnormalities are well-established in Parkinson's disease. Blink rate may be influenced by corneal sub-basal nerve density, however, this relationship has not yet been investigated in Parkinson's disease. This case-control study examined the ocular surface in patients with moderately severe Parkinson's disease, including confocal microscopy of the cornea. Fifteen patients with moderately severe Parkinson's disease (modified Hoehn and Yahr grade 3 or 4) and fifteen control participants were recruited. Ophthalmic assessment included slit-lamp examination, blink rate assessment, central corneal aesthesiometry and in vivo corneal confocal microscopy. The effect of disease laterality was also investigated. Of the 15 patients with Parkinson's disease, ten were male and the mean age was 65.5±8.6years. The corneal sub-basal nerve plexus density was markedly reduced in patients with Parkinson's disease (7.56±2.4mm/mm 2 ) compared with controls (15.91±2.6mm/mm 2 ) (pParkinson's disease (0.79±1.2mBAR) and the control group (0.26±0.35mBAR), p=0.12. Sub-basal nerve density was not significantly different between the eye ipsilateral to the side of the body with most-severe motor symptoms, and the contralateral eye. There was a significant positive correlation between ACE-R scores and sub-basal corneal nerve density (R 2 =0.66, p=0.02). This is the first study to report a significant reduction in corneal sub-basal nerve density in Parkinson's disease and demonstrate an association with cognitive dysfunction. These results provide further evidence to support the involvement of the peripheral nervous system in Parkinson's disease, previously thought to be a central nervous system disorder. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Research on inhibition of corneal neovascularization

    Directory of Open Access Journals (Sweden)

    Zhang-Hui Yang

    2015-12-01

    Full Text Available Corneal transparency is the basis of the normal physiological functions.However, corneal neovascularization(CNVmay occur in the infection, mechanical and chemical injury or under other pathological conditions,which make the cornea lose original transparency and severe visual impairment. In recent years, along with the development of immunology, molecular biology, biochemistry and other disciplines, there is more in-depth understanding on the CNV, and clinical treatment of CNV has made new breakthroughs. This article provides an overview of the inhibition of CNV.

  11. Corneal epithelial inclusion cyst in a dog

    Directory of Open Access Journals (Sweden)

    Campos Carla de Freitas

    2002-01-01

    Full Text Available An unilateral corneal epithelial inclusion cyst in a 7-year-old male Boxer dog is reported. The cyst had been observed for thirty days, was unique, not congenital and only one eye was involved. Seven months prior to the referral the dog had manifested indolent corneal ulcer treated with grade keratotomy and third eyelid flap. The cyst was removed by superficial keratectomy followed by a conjunctival pedicle graft. Recovery was uncomplicated and there wasn?t recurrence seven months after the surgery.

  12. The corneal stroma during contact lens wear.

    Science.gov (United States)

    Jalbert, Isabelle; Stapleton, Fiona

    2005-03-01

    Recent technological advances have lead to novel descriptions of the microanatomy of the corneal stroma. In the first section of this review, these findings and the role they play in the maintenance of vital properties such as corneal transparency, mechanical strength, homeostasis, wound-healing response and metabolism are described. In the second part, contact lens induced stromal alterations such as acidosis, oedema, striae, thinning and opacities are reviewed as well as the more recently described phenomenon of microdot deposits and keratocyte loss with an emphasis on how lens wearing stromal effects can be minimised.

  13. Prediction of flap response.

    Science.gov (United States)

    Potgieter, Frederik J; Roberts, Cynthia; Cox, Ian G; Mahmoud, Ashraf M; Herderick, Edward E; Roetz, Marlize; Steenkamp, Wouter

    2005-01-01

    To find predictors of the induced biomechanical and optical effects of lamellar flap creation on the cornea. Optimed Eye and Laser Clinic, Pretoria, South Africa, and the Department of Ophthalmology and Biomedical Engineering Center, The Ohio State University, Columbus, Ohio, and Bausch & Lomb Vision Research Laboratory, Rochester, New York, USA. This prospective study monitored the refractive, wavefront aberration, and corneal topographic changes in 29 eyes of 15 patients for 3 months after the creation of a corneal lamellar flap. The main outcome measures for statistical analysis were refraction, total corneal thickness, residual corneal bed thickness, horizontal white-to-white corneal diameter, horizontal flap diameter, topography data, and wavefront data. Statistically significant changes were seen in the autorefraction mode. Wavefront data showed significant change in 4 Zernike modes-90/180-degree astigmatism, vertical coma, horizontal coma, and spherical aberration. The topography data indicated the corneal biomechanical response was significantly predicted by stromal bed thickness in the early follow-up period and by total corneal pachymetry and flap diameter in a 2-parameter statistical model in the late follow-up period. Uncomplicated lamellar flap creation is responsible for systematic changes in corneal topography and induction of higher-order optical aberrations. Predictors of this response include stromal bed thickness, flap diameter, and total corneal pachymetry.

  14. Use of soft contact lenses in an eye casualty department for the primary treatment of traumatic corneal abrasions.

    OpenAIRE

    Acheson, J F; Joseph, J; Spalton, D J

    1987-01-01

    We have assessed the role of bandage contact lenses in the primary treatment of traumatic corneal abrasions. Patients treated with bandage lenses healed more quickly (0.05 greater than p greater than 0.02) and with less discomfort (0.05 greater than p greater than 0.02) than those treated traditionally, with the added advantage of maintaining vision during treatment. Resterilisation of contact lenses reduces the cost and makes the treatment economically viable. Large diameter lenses were fitt...

  15. Treatment of progressive keratoconus by riboflavin-UVA-induced cross-linking of corneal collagen: ultrastructural analysis by Heidelberg Retinal Tomograph II in vivo confocal microscopy in humans.

    Science.gov (United States)

    Mazzotta, Cosimo; Balestrazzi, Angelo; Traversi, Claudio; Baiocchi, Stefano; Caporossi, Tomaso; Tommasi, Cristina; Caporossi, Aldo

    2007-05-01

    To assess ultrastructural stromal modifications after riboflavin-UVA-induced cross-linking of corneal collagen in patients with progressive keratoconus. This was a second-phase prospective nonrandomized open study in 10 patients with progressive keratoconus treated by riboflavin-UVA-induced cross-linking of corneal collagen and assessed by means of Heidelberg Retinal Tomograph II Rostock Corneal Module (HRT II-RCM) in vivo confocal microscopy. The eye in the worst clinical condition was treated for each patient. Treatment under topical anesthesia included corneal deepithelization (9-mm diameter) and instillation of 0.1% riboflavin phosphate-20% dextran T 500 solution at 5 minutes before UVA irradiation and every 5 minutes for a total of 30 minutes. UVA irradiation was 7 mm in diameter. Patients were assessed by HRT II-RCM confocal microscopy in vivo at 1, 3, and 6 months after treatment. Rarefaction of keratocytes in the anterior and intermediate stroma, associated with stromal edema, was observed immediately after treatment. The observation at 3 months after the operation detected keratocyte repopulation in the central treated area, whereas the edema had disappeared. Cell density increased progressively over the postoperative period. At approximately 6 months, keratocyte repopulation was complete, accompanied by increased density of stromal fibers. No endothelial damage was observed at any time. Reduction in anterior and intermediate stromal keratocytes followed by gradual repopulation has been confirmed directly in vivo in humans by HRT II-RCM confocal microscopy after riboflavin-UVA-induced corneal collagen cross-linking.

  16. Corneal endothelial cytotoxicity of the Calotropis procera (ushaar) plant.

    Science.gov (United States)

    Al-Mezaine, Hani S; Al-Amry, Mohammed A; Al-Assiri, Abdullah; Fadel, Talal S; Tabbara, Khalid F; Al-Rajhi, Ali A

    2008-05-01

    To report 6 eyes of 5 patients with transient corneal edema after exposure to the milky latex of Calotropis procera (ushaar). Interventional case series. Intracorneal penetration of ushaar latex can lead to permanent endothelial cell loss with morphologic alteration. Corneal edema resolved completely in approximately 2 weeks in all cases, despite reduced endothelial cell count and abnormal morphology. Corneal endothelial toxicity of ushaar latex is caused by its ability to penetrate the corneal stroma and induce permanent loss of endothelial cells. Corneal edema resolves if sufficient endothelial cell viability is still present after resolution of ushaar keratitis.

  17. Reversible Corneal Toxicity of Retained Intracameral Perfluoro-n-octane.

    Science.gov (United States)

    Alharbi, Saad S; Asiri, Mohammed S

    2016-01-01

    A 58-year-old female presented with intracameral retained perfluoro-n-octane (PFO) following previous retinal reattachment surgery. After 4 years of follow-up without related sequelae, the patient complained of a gradual decrease in vision secondary to corneal edema with whitish corneal precipitate inferiorly corresponding to the area of retained PFO. Three weeks after anterior chamber washout, corneal edema resolved and the patient obtained 20/40 visual acuity. Even though PFO considered to have a relatively good safety profile, early anterior chamber washout may prevent corneal toxicity and avoid later persistent corneal decompensation.

  18. Current status of accelerated corneal cross-linking

    Directory of Open Access Journals (Sweden)

    Michael Mrochen

    2013-01-01

    Full Text Available Corneal cross-linking with riboflavin is a technique to stabilize or reduce corneal ectasia, in diseases such as keratoconus and post-laser-assisted in situ keratomileusis (LASIK ectasia. There is an interest by patient as well as clinicians to reduce the overall treatment time. Especially, the introduction of corneal cross-linking in combination with corneal laser surgery demands a shorter treatment time to assure a sufficient patient flow. The principles and techniques of accelerated corneal cross-linking is discussed.

  19. [Measurement of viscoelastic corneal parameters (corneal hysteresis) in patients with primary open angle glaucoma].

    Science.gov (United States)

    Schroeder, B; Hager, A; Kutschan, A; Wiegand, W

    2008-10-01

    The ocular response analyzer (ORA) uses an air-pressure-triggered, dynamic, bi-directional corneal applanation method to measure biomechanical parameters of the cornea. Corneal hysteresis (CH) is defined as the difference in intraocular pressure recorded during inward and outward applanation. CH is therefore an indicator for the viscoelastic properties of the cornea. CH was recorded in non-glaucoma patients (80 eyes) as well as in patients with primary open angle glaucoma (POAG, 82 eyes). The correlation between CH and central corneal thickness (CCT) was analyzed. Mean CH was 10.6+/-2.2 mmHg in the non-glaucoma group and 9.3+/-2.2 mmHg in patients with POAG (pcorneal parameters with a significant decrease in corneal hysteresis. A positive correlation between CH and CCT, which was seen in the non-glaucoma group could not be detected in the POAG group.

  20. Quantitative evaluation of corneal epithelial injury caused by n-heptanol using a corneal resistance measuring device in vivo

    Directory of Open Access Journals (Sweden)

    Fukuda M

    2012-04-01

    Full Text Available Masamichi Fukuda1, Hiroshi Sasaki11Department of Ophthalmology, Kanazawa Medical University, Uchinada, JapanPurpose: We attempted to develop a device for measuring electrical corneal resistance (CR using corneal contact lens electrodes to quantitatively evaluate corneal injury in vivo. In the present study, full-thickness detachment of the corneal epithelium was induced by n-heptanol, and the feasibility of the quantitative evaluation of this injury by corneal contact lens electrodes was evaluated in vivo.Methods: The central area of an albino rabbit's cornea was exposed to a filter paper pre-immersed in n-heptanol for 1 minute to induce injury of the corneal epithelium. After induction of injury, the electrical CR was measured and the percentage of CR (%CR was calculated. Fluorescein solution (3 µL was applied to the wound/affected area of the corneal epithelium for photography with a slit-lamp biomicroscope. The wound/affected area was measured using an image analysis system. The correlation between the %CR and the wound/affected area was analyzed.Results: As the size of the wound/affected area of the corneal epithelium increased, the %CR decreased after corneal epithelium detachment. Thus, a close correlation was found between the area of corneal epithelium detachment and the %CR.Conclusion: The corneal resistance device that we developed was capable of quantitatively evaluating n-heptanol-induced full-thickness injuries of the corneal epithelium.Keywords: eyes in vivo, corneal injury, corneal contact lens electrode corneal resistance device, n-heptanol

  1. Normative values for corneal nerve morphology assessed using corneal confocal microscopy: a multinational normative data set.

    Science.gov (United States)

    Tavakoli, Mitra; Ferdousi, Maryam; Petropoulos, Ioannis N; Morris, Julie; Pritchard, Nicola; Zhivov, Andrey; Ziegler, Dan; Pacaud, Danièle; Romanchuk, Kenneth; Perkins, Bruce A; Lovblom, Leif E; Bril, Vera; Singleton, J Robinson; Smith, Gordon; Boulton, Andrew J M; Efron, Nathan; Malik, Rayaz A

    2015-05-01

    Corneal confocal microscopy is a novel diagnostic technique for the detection of nerve damage and repair in a range of peripheral neuropathies, in particular diabetic neuropathy. Normative reference values are required to enable clinical translation and wider use of this technique. We have therefore undertaken a multicenter collaboration to provide worldwide age-adjusted normative values of corneal nerve fiber parameters. A total of 1,965 corneal nerve images from 343 healthy volunteers were pooled from six clinical academic centers. All subjects underwent examination with the Heidelberg Retina Tomograph corneal confocal microscope. Images of the central corneal subbasal nerve plexus were acquired by each center using a standard protocol and analyzed by three trained examiners using manual tracing and semiautomated software (CCMetrics). Age trends were established using simple linear regression, and normative corneal nerve fiber density (CNFD), corneal nerve fiber branch density (CNBD), corneal nerve fiber length (CNFL), and corneal nerve fiber tortuosity (CNFT) reference values were calculated using quantile regression analysis. There was a significant linear age-dependent decrease in CNFD (-0.164 no./mm(2) per year for men, P < 0.01, and -0.161 no./mm(2) per year for women, P < 0.01). There was no change with age in CNBD (0.192 no./mm(2) per year for men, P = 0.26, and -0.050 no./mm(2) per year for women, P = 0.78). CNFL decreased in men (-0.045 mm/mm(2) per year, P = 0.07) and women (-0.060 mm/mm(2) per year, P = 0.02). CNFT increased with age in men (0.044 per year, P < 0.01) and women (0.046 per year, P < 0.01). Height, weight, and BMI did not influence the 5th percentile normative values for any corneal nerve parameter. This study provides robust worldwide normative reference values for corneal nerve parameters to be used in research and clinical practice in the study of diabetic and other peripheral neuropathies. © 2015 by the American Diabetes Association

  2. The Effect of Corneal Epithelium on Corneal Curvature in Patients with Keratoconus.

    Science.gov (United States)

    Akcay, Emine Kalkan; Uysal, Betul Seher; Sarac, Ozge; Ugurlu, Nagehan; Yulek, Fatma; Cagil, Nurullah; Aslan, Nabi

    2015-01-01

    To investigate the effects of corneal epithelium on corneal curvature in patients with keratoconus. This is a prospective, nonrandomized study. Fifty-nine eyes of 47 patients diagnosed as keratoconus and for whom corneal collagen crosslinking (CXL) was recruited in this study. This study is a single-center clinical trial. Pregnancy, lactation, connective tissue disease, corneal thickness below 350 μm, severe dry eyes, or scar of corneal surgery were exclusion criteria. Before and during CXL procedure after removing the corneal epithelium, maximum values of corneal apical curvature, simulated keratometry 1 (Sim-K1), simulated keratometry 2 (Sim-K2), temporal and inferior curvature values, all of which are 1.5 mm from the corneal center, were calculated. These values before and after removal of epithelium were compared statistically. Mean age of patients was 23.30 ± 5.5 (12-38) years. Twenty-eight (59%) were male while 19 (41%) were female. Mean values measured before and after removing the corneal epithelium were: apical curvature; 59.19 ± 7.2 (47.06-82.40) diopter (D) and 61.70 ± 8.8 (49.19-92.66) D (p = 0.001), SimK1; 47.57 ± 4.3 (39.14-64.57) D and 48.23 ± 4.3 (41.89-66.70) D (p = 0.001), SimK2; 52.04 ± 5.3 (43.56-69.34) D and 53.34 ± 5.6 (43.73-70.89) D (p = 0.001), inferior curvature; 53,85 ± 5.2 (43.47-76.56) D and 55.05 ± 5.8 (44.56-81.93) D (p = 0.002), temporal curvature 49.49 ± 5.1 (41.50-71.03) D and 51.53 ± 5.4 (41.58-73.34) D (p = 0.001), respectively. In keratoconus patients during CXL treatment, after removing the corneal epithelium, more steepness is detected in the curvature of the steeper area of the cornea. When evaluating patients with keratoconus, the masking effect of corneal epithelium on values of curvature should be taken into consideration.

  3. The scale of substratum topographic features modulates proliferation of corneal epithelial cells and corneal fibroblasts

    OpenAIRE

    Liliensiek, S.J.; Campbell, S.; Nealey, P. F.; Murphy, C J

    2006-01-01

    The cornea is a complex tissue composed of different cell types, including corneal epithelial cells and keratocytes. Each of these cell types are directly exposed to rich nanoscale topography from the basement membrane or surrounding extracellular matrix. Nanoscale topography has been shown to influence cell behaviors, including orientation, alignment, differentiation, migration, and proliferation. We investigated whether proliferation of SV40-transformed human corneal epithelial cells (SV40-...

  4. Corneal Biomechanical Assessment Using Corneal Visualization Scheimpflug Technology in Keratoconic and Normal Eyes

    OpenAIRE

    Lei Tian; Yi-Fei Huang; Li-Qiang Wang; Hua Bai; Qun Wang; Jing-Jing Jiang; Ying Wu; Min Gao

    2014-01-01

    Purpose. To compare the corneal biomechanical properties of keratoconic patients and age-matched controls using corneal visualization Scheimpflug technology (Corvis ST). Methods. Sixty keratoconic eyes from 47 keratoconus patients and 60 normal eyes from 60 controls were enrolled in this prospective study. Tomography and biomechanical parameters of all eyes were obtained with the Pentacam and Corvis ST, respectively. Intraocular pressure was measured using a Goldmann applanation tonometer. ...

  5. Increased corneal hysteresis after corneal collagen crosslinking: a study based on applanation resonance technology.

    Science.gov (United States)

    Beckman Rehnman, Jeannette; Behndig, Anders; Hallberg, Per; Lindén, Christina

    2014-12-01

    A reliable tool for quantification of the biomechanical status of the cornea in conjunction with corneal collagen crosslinking (CXL) treatment is needed. To quantify the biomechanical effects of CXL in vivo. A prospective, open, case-control study was conducted at the Department of Ophthalmology, Umeå University, Umeå, Sweden. Participants included 28 patients (29 eyes) aged 18 to 28 years with progressive keratoconus and corresponding age- and sex-matched healthy individuals serving as controls. All participants were monitored during a 6-month period between October 13, 2009, and November 5, 2012. Corneal hysteresis after CXL for keratoconus. A difference in corneal hysteresis between the control group and the patients with keratoconus was found at baseline, both with an applanation resonance tonometer (ART) and an ocular response analyzer (ORA), at mean (SD) values of -1.09 (1.92) mm Hg (99% CI, -2.26 to 0.07; P = .01) and -2.67 (2.55) mm Hg (99% CI, -4.05 to -1.32; P corneal hysteresis was demonstrated with an ART 1 and 6 months after CXL, at 1.2 (2.4) mm Hg (99% CI,-0.1 to 2.5; P = .02) and 1.1 (2.7) mm Hg (99% CI, -0.3 to 2.6; P = .04), respectively, but not with ORA. A decrease in corneal thickness was seen 1 and 6 months after treatment (-24 [26] µm, P corneal flattening of -0.6 (0.7) diopters was seen at 6 months (P corneal hysteresis after CXL treatment. Given the large-scale use of CXL in modern keratoconus treatment, a tool with this capacity has a great potential value. Refinement of the ART method of measuring and quantifying corneal biomechanical properties will be a subject of further studies.

  6. Intraoperative corneal thickness change and clinical outcomes after corneal collagen crosslinking: Standard crosslinking versus hypotonic riboflavin.

    Science.gov (United States)

    Rosenblat, Elan; Hersh, Peter S

    2016-04-01

    To determine intraoperative changes in corneal thickness and outcomes of corneal collagen crosslinking (CXL) using 2 intraoperative regimens: riboflavin-dextran or hypotonic riboflavin. Cornea and refractive surgery practice, Teaneck, New Jersey, USA. Prospective randomized case series. Eyes with keratoconus or corneal ectasia were treated. All eyes received preloading with riboflavin 0.1% in 20% dextran. During ultraviolet-A (UVA) exposure, patients were randomly assigned to 1 of 2 study arms; that is, riboflavin-dextran or hypotonic riboflavin. Intraoperative pachymetry was measured before and after the corneal epithelium was removed, after initial riboflavin loading, and after UVA light exposure. Patients were evaluated for maximum keratometry (K), uncorrected distance visual acuity (UDVA), corrected distance visual acuity, corneal thickness, and endothelial cell count (ECC). Forty-eight eyes were treated. After removal of the epithelium and riboflavin loading, the mean pachymetry was 430 μm and 432 μm in the standard group and hypotonic group, respectively. Immediately after 30-minute UVA administration, the mean pachymetry was 302 μm and 342 μm, respectively. There was no statistically significant difference in the postoperative maximum K change, UDVA, corneal thickness, or ECC between the 2 groups. The cornea thinned substantially during the CXL procedure. The use of hypotonic riboflavin rather than riboflavin-dextran during UVA administration decreased the amount of corneal thinning during the procedure by 30%, from 128 μm to 90 μm. However, there were no significant differences in clinical efficacy or changes in ECC or function between groups postoperatively. In general, corneal thinning during CXL did not seem to compromise the safety of the endothelium. Dr. Hersh is a consultant to Avedro, Inc. Dr. Rosenblat has no financial or proprietary interest in any material or method mentioned. Copyright © 2016 ASCRS and ESCRS. Published by Elsevier

  7. Astigmatism induced by intrastromal corneal suture after small incision phacoemulsification.

    Science.gov (United States)

    Chipont-Benabent, E; Artola Roig, A; Pérez-Santonja, J J; Guisbert Medel, M; Alió Sanz, J L

    1998-04-01

    To evaluate the course of astigmatic evolution and complications after clear corneal incisions using an intrastromal corneal suture. Instituto Oftalmologico de Alicante, University of Alicante, Spain. Eighty eyes of 62 patients had endocapsular phacoemulsification. A foldable intraocular lens was implanted through a 4.0 mm clear corneal incision. A 10-0 nylon intrastromal corneal suture was used in all eyes. Change sin corneal astigmatism were calculated by vector analysis; follow-up was 6 months. Early and late suture-related complications were also evaluated. Mean induced cylinder was 1.25 diopters (D) +/- 1.24 (SD) with the wound 1 day postoperatively and 0.19 +/- 0.81 D against the wound at 6 months. There were no incision- or suture-related complications postoperatively. Use of the intrastromal corneal suture led to astigmatically neutral closure of multiplanar corneal incisions.

  8. [Clinical observation of astigmatism induced by corneal incision after phacoemulsification].

    Science.gov (United States)

    Xie, L; Zhu, G; Wang, X

    2001-03-01

    To evaluate the changes of astigmatism induced by corneal incision after phacoemulsification. Phacoemulsification was performed on 62 cases (78 eyes) without suture for a corneal incision. The changes of corneal astigmatism before and after operation in group A (incision at the superior nasal or superior temporal) and B (incision at the steepest corneal meridian) were compared. Three months after the operation, the surgical induced astigmatism was (0.83 plus minus 0.65) D and (0.72 plus minus 0.55) D in group A and B respectively. There was no significant difference, statistically (P > 0.05). The changes of corneal astigmatism were 0.11 D and 0.39 D in group A and B respectively, the difference being statistically significant (P astigmatism is very small after a corneal incision in phacoemulsification without a suture. If the incision is placed on the steepest meridian, the corneal astigmatism can be significantly reduced postoperatively.

  9. Immediately observation on post-LASIK corneal flap

    Directory of Open Access Journals (Sweden)

    Kun Wu

    2014-08-01

    Full Text Available AIM:To immediately observe the complication of corneal flap after LASIK surgery.METHODS:A retrospective case series were studies.Totally 2 040 cases(4 080 eyesfrom January 2010 to October 2012 in our hospital were collected, the corneal flap was observed using lamp microscope after LASIK within 30min. Corneal flap dislocation, corneal flap strial and intraface debris were examined after operation, the effective treatment and controlled measure should be taken for these complications.RESULTS: Postoperative complications were corneal flap dislocation 102 eyes(2.5%, corneal flapstriae 95 eyes(2.33%, interface debris 105 eyes(2.57%. No failure case was seen. There had no corneal flap-related complications, which seriously impact the visual quality after the surgery.CONCLUSION: Carefully postoperative examination at the first-time is an effective way to manage some complications of post-LASIK. Thus promoting the diagnosis and treatment of post-LASIK complications.

  10. Enhancement of Corneal Visibility in Optical Coherence Tomography Images with Corneal Opacification.

    Science.gov (United States)

    Chung, Cheuk Wang; Ang, Marcus; Farook, Mohamed; Strouthidis, Nicholas G; Mehta, Joddhbir S; Mari, Jean Martial; Girard, Michaël J A

    2016-09-01

    To establish and to rank the performance of a corneal adaptive compensation (CAC) algorithm in enhancing corneal images with scars acquired from three commercially available anterior segment optical coherence tomography (ASOCT) devices. Horizontal B-scans of the cornea were acquired from 10 patients using three ASOCT devices (Spectralis, RTVue, and Cirrus). We compared ASOCT image quality (with and without CAC) by computing the intralayer contrast (a measure of shadow removal), the interlayer contrast (a measure of tissue boundary visibility), and the tissue/background contrast (a measure of overall corneal visibility). All six groups (Spectralis, RTVue, Cirrus, Spectralis+CAC, RTVue+CAC, and Cirrus+CAC) were ranked according to a global performance index that averaged all contrast quantities. CAC provided mean intralayer contrasts improvement for all devices (all P images of corneal scars may be enhanced by CAC through shadow removal, improved tissue boundary visibility, and enhanced corneal visibility against the image background. RTVue produces the finest baseline images but the best image quality can be achieved by applying CAC to Spectralis images. CAC could enhance visibility of corneal images with scars acquired from commercially available ASOCT devices and could aid preoperative planning of patients for ophthalmic procedures.

  11. "Tuck In" Lamellar Keratoplasty (TILK) for corneal ectasias involving corneal periphery.

    Science.gov (United States)

    Kaushal, S; Jhanji, V; Sharma, N; Tandon, R; Titiyal, J S; Vajpayee, R B

    2008-02-01

    Evaluation of a new surgical technique for the management of corneal ectasia with peripheral corneal involvement. Twelve eyes of 12 patients with corneal ectasias and peripheral corneal thinning requiring surgical intervention, including eight patients with combined keratoconus and PMD and four patients of keratoglobus, were enrolled for the study in a tertiary care hospital. All patients were contact lens intolerant and had a best corrected visual acuity (BCVA) Keratoplasty (TILK) that included a central lamellar keratoplasty with intrastromal tucking of the peripheral flange was performed in these patients. The main outcome measures analysed were uncorrected visual acuity (UCVA), BCVA, keratometry, refractive status and time for epithelial healing. At the last follow-up (mean: 1.7 years (range 13-48 months)), six patients (50.0%) had BCVA >/=20/60, and all patients had BCVA >/=20/80. The mean keratometry decreased from 57.54 (SD 6.89) D preoperatively to 46.36 (2.39) D (p = 0.003), and the mean spherical equivalent (SEQ) refractive error decreased from -7.8 (4.6) D preoperatively to 1.23 (1.88) D (p = 0.007). A significant decrease was also seen in mean refractive astigmatism which decreased from 5.93 (3.06) D preoperatively to 3.23 (1.14) D (p = 0.037). Our technique of TILK is an effective surgical modality for the management of ectatic corneal dystrophies with peripheral corneal thinning.

  12. [Corneal aberrations before and after corneal and corneoscleral small incision cataract surgery].

    Science.gov (United States)

    Kissner, A; Kohlhaas, M; Spörl, E; Pillunat, L E

    2007-02-01

    The corneal as well as the corneoscleral incisions are considered to be standard in cataract surgery. However, both incision techniques have their advantages and disadvantages. We investigated whether the way of performing the incisions has different effects on the corneal wavefront, especially on higher-order aberrations. Each of 26 patients (6 men, 20 women), aged between 62 and 85 years (average 74.9 +/- 6.69 years), received a standard phakoemulsification by performing a corneal incision on the right eye (group 1) and a corneoscleral incision on the left eye (group 2). The corneal surface was preoperatively investigated by using the corneal wavefront instrument Optikon Keratron Scout, (Schwind Company, Germany). After 6 to 8 weeks the same parameters were measured again. The statistical analysis of the pre- and postoperative data within the same group indicated significant differences (p < 0.05) in group 1 for Z (3 +/- 3) = Trefoil and in group 2 for Z (2 +/- 2) = Astigmatism. On comparing the postoperative data of the corneal incision with those of the corneoscleral incision, there was only a significant difference (p < 0.05) for Z (3 +/- 3) = Trefoil. In accordance with the induced higher-order aberrations both surgical techniques can be considered as being equivalent.

  13. Corneal Backscatters as an Objective Index for Assessing Fuchs’ Endothelial Corneal Dystrophy: A Pilot Study

    Directory of Open Access Journals (Sweden)

    Hsueh-Yen Chu

    2017-01-01

    Full Text Available Purpose. To provide an objective, quantitative approach for monitoring Fuchs’ endothelial corneal dystrophy (FECD, with Scheimpflug imaging. Design. This is a retrospective case-control pilot study. Methods. The study group consisted of 53 eyes in 27 patients diagnosed with FECD, with normal subjects paired as control. Main outcome measures were corneal thickness, morphological patterns on densitograms, and indices of corneal density including the average area density (mean AD and the average ratio of Descemet’s membrane density versus area density (DM/AD in Pentacam Scheimpflug images. Results. There were no significant differences in age and corneal thickness between FECD and normal groups. Morphologically, hanging-hammock patterns were noted on the densitograms of FECD patients, which were different from the high-back chair patterns in normal subjects. Quantitatively, mean AD and DM/AD were both elevated in FECD patients as compared with normal subjects (P=0.01 and 0.025, resp.. In addition, FECD patients with corneal edema had significantly higher mean AD (P=0.018 than those without corneal edema. Conclusions. This pilot study shows that Pentacam system provides an objective, quantitative way to approach FECD corneas. It can assist ophthalmologists in detecting the early change and in monitoring disease progression of FECD. Further studies are needed to consolidate the findings.

  14. Corneal Biomechanical Changes after Crosslinking for Progressive Keratoconus with the Corneal Visualization Scheimpflug Technology

    Directory of Open Access Journals (Sweden)

    Johannes Steinberg

    2014-01-01

    Full Text Available Purpose. To evaluate the effect of corneal crosslinking in progressive keratoconus by applying in vivo corneal visualization Scheimpflug technology. Design. Longitudinal retrospective study. Subjects and Controls. Seventeen eyes of patients treated with corneal crosslinking for progressive keratoconus. Methods. Corneal visualization Scheimpflug technology analyses (research software version 6.07r08 of subjects with progressive keratoconus before and 3 months after corneal crosslinking (CXL were reviewed retrospectively. t-test (for normal distribution and Wilcoxon matched-pairs test (if not normally distributed were used to test for statistically significant differences between pre- and post-CXL analyses. Results. We demonstrated statistically significant differences for the intraocular pressure (median: +3 mmHg, P =0.004, the central corneal pachymetry (pachy; mean: −35 µm, P<0.001, the timespan between the air impulse release and the first applanation of the cornea (A1time; median: +0.12 ms, P<0.05, and the timespan between the air impulse release and the second applanation of the cornea (A2time; median: −37 ms, P<0.05. Conclusions. With the A1time and the A2time, we identified two parameters that demonstrated a statistically significant improvement of the biomechanical properties of the cornea after CXL. Despite the known initial decrease of the pachymetry after CXL, none of the analyzed parameters indicated a progression of the keratoconus.

  15. A brief history of corneal transplantation: From ancient to modern

    Directory of Open Access Journals (Sweden)

    Alexandra X Crawford

    2013-01-01

    Full Text Available This review highlights many of the fundamental concepts and events in the development of corneal transplantation - from ancient times to modern. Tales of eye, limb, and even heart transplantation appear in ancient and medieval texts; however, in the scientific sense, the original concepts of corneal surgery date back to the Greek physician Galen (130-200 AD. Although proposals to provide improved corneal clarity by surgical interventions, including keratoprostheses, were better developed by the 17 th and 18 th centuries, true scientific and surgical experimentation in this field did not begin until the 19 th century. Indeed, the success of contemporary corneal transplantation is largely the result of a culmination of pivotal ideas, experimentation, and perseverance by inspired individuals over the last 200 years. Franz Reisinger initiated experimental animal corneal transplantation in 1818, coining the term "keratoplasty". Subsequently, Wilhelmus Thorne created the term corneal transplant and 3 years later Samuel Bigger, 1837, reported successful corneal transplantation in a gazelle. The first recorded therapeutic corneal xenograft on a human was reported shortly thereafter in 1838-unsurprisingly this was unsuccessful. Further progress in corneal transplantation was significantly hindered by limited understanding of antiseptic principles, anesthesiology, surgical technique, and immunology. There ensued an extremely prolonged period of debate and experimentation upon the utility of animal compared to human tissue, and lamellar versus penetrating keratoplasty. Indeed, the first successful human corneal transplant was not performed by Eduard Zirm until 1905. Since that first successful corneal transplant, innumerable ophthalmologists have contributed to the development and refinement of corneal transplantation aided by the development of surgical microscopes, refined suture materials, the development of eye banks, and the introduction of

  16. Corneal ulcers: For the general practitioner

    African Journals Online (AJOL)

    the skin, e.g. herpes zoster scars, lid lacerations, burns. Lid malposition should be excluded. Facial nerve function must be assessed as dysfunction could affect ... Corneal in ltrate seen as haziness or whitening of the usually transparent cornea is universal to infective ulcers in varying degrees. is signi es the inflammatory ...

  17. Corneal topography measurements for biometric applications

    Science.gov (United States)

    Lewis, Nathan D.

    The term biometrics is used to describe the process of analyzing biological and behavioral traits that are unique to an individual in order to confirm or determine his or her identity. Many biometric modalities are currently being researched and implemented including, fingerprints, hand and facial geometry, iris recognition, vein structure recognition, gait, voice recognition, etc... This project explores the possibility of using corneal topography measurements as a trait for biometric identification. Two new corneal topographers were developed for this study. The first was designed to function as an operator-free device that will allow a user to approach the device and have his or her corneal topography measured. Human subject topography data were collected with this device and compared to measurements made with the commercially available Keratron Piccolo topographer (Optikon, Rome, Italy). A third topographer that departs from the standard Placido disk technology allows for arbitrary pattern illumination through the use of LCD monitors. This topographer was built and tested to be used in future research studies. Topography data was collected from 59 subjects and modeled using Zernike polynomials, which provide for a simple method of compressing topography data and comparing one topographical measurement with a database for biometric identification. The data were analyzed to determine the biometric error rates associated with corneal topography measurements. Reasonably accurate results, between three to eight percent simultaneous false match and false non-match rates, were achieved.

  18. Relationship between Central Corneal Thickness, Vitreous ...

    African Journals Online (AJOL)

    Shufelt C, Fraser-Bell S, Ying-Lai M, Torres M, Varma R. Refractive error, ocular biometry, and lens opalescence in an adult population: The Los Angeles Latino .... J. Age-related changes in central corneal thickness in normal eyes among the adult Lithuanian population. Clinical Interventions in Aging. 2014; 9: 1145-1151.

  19. Corneal Intelligence | Murdoch | Nigerian Journal of Ophthalmology

    African Journals Online (AJOL)

    Nigerian Journal of Ophthalmology. Journal Home · ABOUT · Advanced Search · Current Issue · Archives · Journal Home > Vol 19, No 1 (2011) >. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register. Corneal Intelligence. I Murdoch. Abstract. No Abstract. Full Text:.

  20. Emergency visits after corneal transplantation in Yemen

    Directory of Open Access Journals (Sweden)

    Mahfouth Abdalla Bamashmus

    2017-01-01

    CONCLUSION: Proper postoperative care is critical for a successful keratoplasty; early intervention of sight-threatening complications increases the chance of graft survival and best-obtained vision. In our corneal transplantation service, all patients are routinely instructed to arrange a same day emergency visit if they experience any symptom in eyes that have undergone keratoplasty.

  1. In vivo characterization of corneal biomechanics.

    Science.gov (United States)

    Piñero, David P; Alcón, Natividad

    2014-06-01

    Interest in corneal biomechanics has increased with the development of new refractive surgery techniques aimed at modifying corneal properties and a variety of surgical options for corneal ectasia management. The human cornea behaves as soft biological material. It is a viscoelastic tissue and its response to a force applied to it depends not only on the magnitude of the force, but also on the velocity of the application. There are concerns about the limitations to measuring corneal biomechanical properties in vivo. To date, 2 systems are available for clinical use: the Ocular Response Analyzer, a dynamic bidirectional applanation device, and the Corvis ST, a dynamic Scheimpflug analyzer device. These devices are useful in clinical practice, especially for planning some surgical procedures and earlier detection of ectatic conditions, but further research is needed to connect the clinical measurements obtained with these devices to the standard mechanical properties. Neither author has a financial or proprietary interest in any material or method mentioned. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  2. Polysaccharide coating of human corneal endothelium

    DEFF Research Database (Denmark)

    Schroder, H D; Sperling, S

    1977-01-01

    Electron microscopy revealed the presence of a 600-1500 A thick layer of polysaccharide on the surface of human corneal endothelial cells. The surface layer was visualized by combined fixation and staining in a mixture of ruthenium red and osmium tetroxide. The coating material was stable...

  3. Serological profile of candidates for corneal donation

    Directory of Open Access Journals (Sweden)

    Adroaldo Lunardelli

    2014-10-01

    Full Text Available Objetive: The purpose of this study is to map the serological profile of candidates to corneal donation at Irmandade Santa Casa de Misericórdia de Porto Alegre, identifying the percentage of disposal by serology and the marker involved. Methods: There have been analised – retrospectively – the results of serology of all corneal donors, made between the period of 1st january 2006 and 31st december 2012. Data analised were related to age, gender and the results of serology pertinent to viral markers (HBsAg, anti-HBc, anti-HCV and anti-HIV, these, determined by immunosorbent tests (ELISA. Results: In the period of the study, there were 2476 corneal donors at the institution, with a major incidence on the male gender, on an average of 58.7 years old. 23% of retention because of serological unfitness was also identified, that is, 570 samples were non-negative to any of the used tests. The marker anti- HBc was the most prevalent on the studied population, followed by the Hepatitis C virus (HCV and by the Human Immunodeficiency Virus (HIV. Conclusion: From the data found through this study, it is essential to have the participation of an efficient service on the serological evaluation of the candidates to corneal donation, once the security of the receptor must be taken into consideration in a population of donors with 23% of unfitness prevalence, in which the most prevalent marker is the one of Hepatits B.

  4. Influence of Pterygium on Corneal Biomechanical Properties.

    Science.gov (United States)

    Öner, Veysi; Taş, Mehmet; Özkaya, Erdal; Bulut, Asker

    2016-07-01

    To evaluate the influence of pterygium on corneal biomechanical properties as measured by the ocular response analyzer (ORA). ORA measurements of 48 eyes with primary nasal pterygium were compared with those of healthy fellow eyes. The mean age of the patients was 46.6 ± 18.9 years. Corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg), and corneal-compensated IOP (IOPcc) were obtained for each subject by using the ORA (Reichert Ophthalmic Instruments, Depew, NY). CH and CRF were significantly lower in the eyes with pterygium than in the healthy fellow eyes (p1 = 0.011, p2 = 0.014, respectively). On the other hand, there were no significant differences between the eyes with pterygium and healthy fellow eyes concerning IOPg and IOPcc (p1 = 0.948, p2 = 0.129, respectively). The present study showed that biomechanical properties measured by ORA were affected by pterygium. The eyes with primary nasal pterygium had lower CH and CRF than healthy fellow eyes. Therefore, the effect of pterygium should be taken into account in order to make correct diagnoses by ORA.

  5. Change in corneal curvature induced by surgery

    NARCIS (Netherlands)

    G. van Rij (Gabriel)

    1987-01-01

    textabstractThe first section deals with the mechanisms by which sutures, incisions and intracorneal contact lenses produce a change in corneal curvature. To clarify the mechanisms by which incisions and sutures produce astigmatism, we made incisions and placed sutures in the corneoscleral limbus

  6. Morphological evaluation of normal human corneal epithelium

    DEFF Research Database (Denmark)

    Ehlers, Niels; Heegaard, Steffen; Hjortdal, Jesper

    2010-01-01

    eyes were evaluated. The central epithelial, stromal and total corneal thickness was measured as 36.0 µm, 618 µm and 651µm, respectively, with a variation coefficient from 0.21 to 0.22. Pathological appearances were found in 27% of corneas, including thickened basement membrane and alterations...

  7. Past and present of corneal refractive surgery

    DEFF Research Database (Denmark)

    Vestergaard, Anders Højslet

    Surgical correction of refractive errors is becoming increasingly popular. In the 1990s, the excimer laser revolutionized the field of corneal refractive surgery with PRK and LASIK, and lately refractive lenticule extraction (ReLEx) of intracorneal tissue, using only a femtosecond laser, has become...

  8. Corneal Intelligence | Murdoch | Nigerian Journal of Ophthalmology

    African Journals Online (AJOL)

    Nigerian Journal of Ophthalmology. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 19, No 1 (2011) >. Log in or Register to get access to full text downloads. Username, Password, Remember me, or Register. Corneal Intelligence. I Murdoch. Abstract. No Abstract.

  9. Relationship between Central Corneal Thickness, Vitreous ...

    African Journals Online (AJOL)

    The central corneal thickness (CCT), Vitreous chamber depth (VCD) and axial length (AL) are important ocular parameters used in the assessment of ocular health in relation to some ocular morbidities. Determining the differences in these parameters in relation to each other is fundamental to understanding the general eye ...

  10. Inhibition of Corneal Neovascularization by Hydrazinocurcumin

    African Journals Online (AJOL)

    This article previously published in Volume 15 Issue 2 of this journal in February 2016 has been retracted in line with the guidelines from the Committee on Publication Ethics (COPE, http://publicationethics.org/resources/guidelines). Retracted: Zhan W, Zhu J, Zhang Y. Inhibition of corneal neovascularization by ...

  11. Retracted: Inhibition of Corneal Neovascularization by ...

    African Journals Online (AJOL)

    This article previously published in Volume 15 Issue 2 of this journal in February 2016 has been retracted in line with the guidelines from the Committee on Publication Ethics (COPE, http://publicationethics.org/resources/guidelines). Retracted: Zhan W, Zhu J, Zhang Y. Inhibition of corneal neovascularization by ...

  12. The Relationship between Central Corneal Thickness and ...

    African Journals Online (AJOL)

    The aim of this study was to investigate the relationship between central corneal thickness (CCT) and intraocular pressure (IOP) in a predominantly black population. A total of eighty-five subjects (right eyes) with mean age 44.7 ± 15.1 years consisting of 49 males and 36 females were recruited for this study. The central ...

  13. Mathematical analysis of corneal oxygenation | Avtar | International ...

    African Journals Online (AJOL)

    Purpose: To develop a quasi steady state model for the time course concentration profile describing the oxygen diffusion and consumption in a multilayered corneal tissue and investigate the effect of various model parameters on the oxygen concentration for open and closed eyes. Method: A simple mathematical model for ...

  14. Functional evaluation of corneal endothelium by combined measurement of corneal volume alteration and cell density after phacoemulsification.

    Science.gov (United States)

    Suzuki, Hisaharu; Oki, Kotaro; Takahashi, Keizo; Shiwa, Toshihiko; Takahashi, Hiroshi

    2007-12-01

    To assess a new method of functional evaluation of corneal endothelium using combined measurement of corneal volume alteration and cell density (CD) after phacoemulsification. Nippon Medical School Hospital, Tokyo, Japan. Phacoemulsification was performed in 28 cases. The corneal volume within 3.0 mm and 10.0 mm circles of the cornea was measured using Scheimpflug imaging (Pentacam, Oculus, Inc.) and the cell density, using specular microscopy (Noncon Robo, Konan Medical). The volume stress index (VSI), a parameter for measuring functional evaluation, was calculated by dividing the volume increase within the 3.0 mm circle (preoperative corneal volume - corneal volume at time of measurement) by the central cell density value. The resulting value is indicative of the amount of postoperative increase in corneal volume with which each corneal endothelial cell should be able to cope. Three months after surgery, the 3.0 mm corneal volume returned to preoperative values, while the 10.0 mm corneal volume remained significantly higher than preoperatively. The cell density values did not significantly change throughout the study. The VSI showed a significant decrease by 7 days after surgery followed by a gradual decrease until the end of the study. At 3 months, the VSI value was significantly smaller than at 1 day. The corneal volume increase after surgery may be indicative of the degree of the endothelial damage in the area; thus, the VSI may be useful in the functional assessment of the corneal endothelium.

  15. Endothelin-1 enhances corneal fibronectin deposition and promotes corneal epithelial wound healing after photorefractive keratectomy in rabbits.

    Science.gov (United States)

    Lai, Yu-Hung; Wang, Hwei-Zu; Lin, Chang-Ping; Hong, Show-Jen; Chang, Shun-Jen

    2008-05-01

    The objective was to study the effects of endothelin-1 (ET1) on corneal wound healing after photorefractive keratectomy (PRK) in rabbit corneas. Following PRK, 18 New Zealand white rabbits were treated with ET1 in the right eyes and with phosphate-buffered salt solution (PBS) in the left eyes. Corneal epithelial wound size, corneal haze and corneal thickness were recorded. Corneal extracellular matrixes, including collagen types 3, 4 and 7, chondroitin sulfate and fibronectin, were investigated using immunohistochemistry study. ET1 increased the rate of healing of corneal epithelial wounds in rabbits. Anti-fibronectin fluorescence was present at week 12 and week 24 in ET1-treated eyes but not in the control eyes. There were no significant differences in corneal haze, corneal thickness and changes in other extracellular matrixes between ET1- and PBS-treated eyes. ET1 can enhance the deposition of fibronectin in corneal stroma and promote corneal epithelial wound healing after PRK. The increase in fibronectin probably explains the increased healing rate of corneal epithelial wounds.

  16. Endothelin-1 Enhances Corneal Fibronectin Deposition and Promotes Corneal Epithelial Wound Healing after Photorefractive Keratectomy in Rabbits

    Directory of Open Access Journals (Sweden)

    Yu-Hung Lai

    2008-05-01

    Full Text Available The objective was to study the effects of endothelin-1 (ET1 on corneal wound healing after photorefractive keratectomy (PRK in rabbit corneas. Following PRK, 18 New Zealand white rabbits were treated with ET1 in the right eyes and with phosphate-buffered salt solution (PBS in the left eyes. Corneal epithelial wound size, corneal haze and corneal thickness were recorded. Corneal extracellular matrixes, including collagen types 3, 4 and 7, chondroitin sulfate and fibronectin, were investigated using immunohistochemistry study. ET1 increased the rate of healing of corneal epithelial wounds in rabbits. Anti-fibronectin fluorescence was present at week 12 and week 24 in ET1-treated eyes but not in the control eyes. There were no significant differences in corneal haze, corneal thickness and changes in other extracellular matrixes between ET1- and PBS-treated eyes. ET1 can enhance the deposition of fibronectin in corneal stroma and promote corneal epithelial wound healing after PRK. The increase in fibronectin probably explains the increased healing rate of corneal epithelial wounds.

  17. 7 CFR 51.320 - Diameter.

    Science.gov (United States)

    2010-01-01

    ... Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE REGULATIONS AND STANDARDS UNDER THE AGRICULTURAL MARKETING ACT OF 1946... Standards for Grades of Apples Definitions § 51.320 Diameter. When measuring for minimum size, “diameter...

  18. Height - Diameter predictive equations for Rubber (Hevea ...

    African Journals Online (AJOL)

    BUKOLA

    Keywords: height-diameter equations, allometric models, predictive equations, sigmoidal curve. INTRODUCTION. Among pertinent tree characteristics for quantitative tree measurements and reasonable prediction are diameter at breast (dbh) and height. They proffer logistic data for modeling and futuristic prediction for ...

  19. Diameter preserving linear maps and isometries, II

    Indian Academy of Sciences (India)

    In this paper we study diameter preserving mappings on spaces of affine functions. Precisely, let S be a compact convex set in a locally convex Hausdorff space and let eЕSЖ be the space of all (real or complex) continuous affine functions on S. We are interested in linear bijections on eЕSЖ which preserve the diameter of ...

  20. The effect of optic asphericity on visual rehabilitation of corneal ectasia with a prosthetic device.

    Science.gov (United States)

    Hussoin, Trisha; Le, Hong-Gam; Carrasquillo, Karen G; Johns, Lynette; Rosenthal, Perry; Jacobs, Deborah S

    2012-09-01

    To study the effect of optic asphericity on visual rehabilitation of corneal ectasia with a prosthetic device. Subjects with corneal ectasia treated with a fluid-ventilated gas-permeable prosthetic device of diameter 18.0-19.0 mm, who had subjective improvement of good Snellen vision with introduction of optic asphericity, were studied. Best corrected Snellen visual acuity (BCVA) under standard illumination, high contrast visual acuity (HCVA), low contrast visual acuity (LCVA), and wavefront aberrations were measured in a sequence of devices that varied per patient only in presence or amount of ellipsoidal front surface optical eccentricity (FSE). Five eyes of 5 subjects were studied. (M:F = 3:2; Age: 20-76). Mean steepest SimK was 57.72±8.30 D. BCVA was ≥20/30 in all eyes in all prosthetic devices, regardless of FSE. Although FSE improved BCVA, HCVA, and LCVA in each patient, no optimal amount could be identified in this small series. Asphericity in the form of 0.6 or 0.8 FSE improved HCVA, LCVA, or both in each patient. FSE was associated with a trend toward reduction of higher-order aberrations, particularly coma. Optic asphericity shows promise for optimization of vision in the rehabilitation of corneal ectasia with a prosthetic device.

  1. Current status of corneal collagen cross-linking for keratoconus: a review.

    Science.gov (United States)

    Chan, Elsie; Snibson, Grant R

    2013-03-01

    Over the past decade, corneal collagen cross-linking has become commonplace as a treatment option for individuals with progressive keratoconus. This is based on laboratory data suggesting that cross-linking using riboflavin and ultraviolet-A irradiation increases collagen diameter and the biomechanical strength of the treated cornea. Case series and limited randomised controlled trials support these findings with data demonstrating that cross-linking slows and possibly halts the progression of keratoconus. In some patients cross-linking results in an improvement in maximum corneal curvature, visual acuity, spherical equivalent and higher-order aberrations. The number of reported complications is small. More recently, variations in the treatment protocol have been described, although they have not yet been subject to comparative studies. While the published data indicate cross-linking is effective in modifying the natural history of keratoconus, the long-term impact of this treatment is still unknown. This paper reviews the theoretical basis, pre-clinical research and clinical results of corneal collagen cross-linking in keratoconus. © 2013 The Authors. Clinical and Experimental Optometry © 2013 Optometrists Association Australia.

  2. Optimal size and location for corneal rotational autografts: a simplified mathematical model.

    Science.gov (United States)

    Afshari, Natalie A; Duncan, Scott M; Tanhehco, Tasha Y; Azar, Dimitri T

    2006-03-01

    To calculate clinical guidelines for the optimal location and size of a rotational autokeratoplasty. The ideal graft size and trephine decentration for a rotational autograft were calculated based on scar location using geometric models. Mathematical variables were set to maximize postoperative visual acuity and for generalization of the geometric model. This model was used in a rotational autokeratoplasty of a patient with a history of a corneal scar and diplopia. An 8-mm autograft was decentered 0.5 mm superiorly and rotated 180 degrees to relocate the scar to the superior aspect of the cornea, out of the patient's vision. For cases that satisfy the given variables, a graft diameter of 8 mm with a decentration of 0.5 mm balances maximization of scar removal and scar movement superiorly, with minimization of discrepancy in corneal thickness after rotation. For scars that are alpha degrees from horizontal, the graft should be rotated 180 - alpha degrees . By using these calculations, the autograft in this case successfully resolved the diplopia and improved visual acuity. A rotational autograft can be an effective alternative to standard penetrating keratoplasty for some patients with corneal scars. We establish a mathematical model for most clinical instances of a rotational autograft, in which an 8-mm graft with a decentration of 0.5 mm best satisfies the goals of surgery.

  3. Transverse depth-dependent changes in corneal collagen lamellar orientation and distribution

    Science.gov (United States)

    Abass, Ahmed; Hayes, Sally; White, Nick; Sorensen, Thomas; Meek, Keith M.

    2015-01-01

    It is thought that corneal surface topography may be stabilized by the angular orientation of out-of plane lamellae that insert into the anterior limiting membrane. In this study, micro-focus X-ray scattering data were used to obtain quantitative information about lamellar inclination (with respect to the corneal surface) and the X-ray scatter intensity throughout the depth of the cornea from the centre to the temporal limbus. The average collagen inclination remained predominantly parallel to the tissue surface at all depths. However, in the central cornea, the spread of inclination angles was greatest in the anterior-most stroma (reflecting the increased lamellar interweaving in this region), and decreased with tissue depth; in the peripheral cornea inclination angles showed less variation throughout the tissue thickness. Inclination angles in the deeper stroma were generally higher in the peripheral cornea, suggesting the presence of more interweaving in the posterior stroma away from the central cornea. An increase in collagen X-ray scatter was identified in a region extending from the sclera anteriorly until about 2 mm from the corneal centre. This could arise from the presence of larger diameter fibrils, probably of scleral origin, which are known to exist in this region. Incorporation of this quantitative information into finite-element models will further improve the accuracy with which they can predict the biomechanical response of the cornea to pathology and refractive procedures. PMID:25631562

  4. Transverse depth-dependent changes in corneal collagen lamellar orientation and distribution.

    Science.gov (United States)

    Abass, Ahmed; Hayes, Sally; White, Nick; Sorensen, Thomas; Meek, Keith M

    2015-03-06

    It is thought that corneal surface topography may be stabilized by the angular orientation of out-of plane lamellae that insert into the anterior limiting membrane. In this study, micro-focus X-ray scattering data were used to obtain quantitative information about lamellar inclination (with respect to the corneal surface) and the X-ray scatter intensity throughout the depth of the cornea from the centre to the temporal limbus. The average collagen inclination remained predominantly parallel to the tissue surface at all depths. However, in the central cornea, the spread of inclination angles was greatest in the anterior-most stroma (reflecting the increased lamellar interweaving in this region), and decreased with tissue depth; in the peripheral cornea inclination angles showed less variation throughout the tissue thickness. Inclination angles in the deeper stroma were generally higher in the peripheral cornea, suggesting the presence of more interweaving in the posterior stroma away from the central cornea. An increase in collagen X-ray scatter was identified in a region extending from the sclera anteriorly until about 2 mm from the corneal centre. This could arise from the presence of larger diameter fibrils, probably of scleral origin, which are known to exist in this region. Incorporation of this quantitative information into finite-element models will further improve the accuracy with which they can predict the biomechanical response of the cornea to pathology and refractive procedures.

  5. Type V collagen and Bowman's membrane. Quantitation of mRNA in corneal epithelium and stroma.

    Science.gov (United States)

    Gordon, M K; Foley, J W; Birk, D E; Fitch, J M; Linsenmayer, T F

    1994-10-07

    Bowman's membrane is an acellular matrix of the cornea which lies between the epithelial basal lamina and the corneal stroma. By immunoelectron microscopy, we have determined that types I and V collagen are components of the collagen fibrils in Bowman's membrane of the chick cornea. Although these same components are found in the fibrils of the stroma, the fibrils of Bowman's membrane are smaller in diameter and less uniform than those of the stroma. At early stages of development, the corneal epithelium synthesizes the types I and II collagen of the primary stroma. We therefore asked whether it might also be capable of synthesizing the type V collagen found in Bowman's membrane at later stages of development. Our results, using competitive polymerase chain reaction to quantitate mRNA from avian corneal cells, indicate that the amount of alpha 1(V) collagen mRNA present in epithelia, relative to alpha 2(I) collagen mRNA, is greater than that in stromal fibroblasts. We postulate that this enables the epithelium to synthesize a higher ratio of type V to type I collagen than the stroma and that this proportionally higher amount of type V might account for the ultrastructural appearance of the fibrils in Bowman's membrane.

  6. Collagen fibrillogenesis in vitro: interaction of types I and V collagen regulates fibril diameter.

    Science.gov (United States)

    Birk, D E; Fitch, J M; Babiarz, J P; Doane, K J; Linsenmayer, T F

    1990-04-01

    The small-diameter fibrils of the chick corneal stroma are heterotypic, composed of both collagen types I and V. This tissue has a high concentration of type V collagen relative to other type I-containing tissues with larger-diameter fibrils, suggesting that heterotypic interactions may have a regulatory role in the control of fibril diameter. The interactions of collagen types I and V were studied using an in vitro self-assembly system. Collagens were purified from lathyritic chick embryos in the presence of protease inhibitors. The type V collagen preparations contained higher molecular weight forms of the alpha 1(V) and alpha 2(V) chains constituting 60-70% of the total. Rotary-shadow electron micrographs showed a persistence of a small, pepsin-sensitive terminal region in an amount consistent with that seen by electrophoresis. In vitro, this purified type V collagen formed thin fibrils with no apparent periodicity, while type I collagen fibrils had a broad distribution of large diameters. However, when type I collagen was mixed with increasing amounts of type V collagen a progressive and significant decrease in both the mean fibril diameter and the variance was observed for D periodic fibrils. The amino-terminal domain of the type V collagen molecule was required for this regulatory effect and in its absence little diameter reducing activity was observed. Electron microscopy using collagen type-specific monoclonal antibodies demonstrated that the fibrils formed were heterotypic, containing both collagen types I and V. These data indicate that the interaction of type V with type I collagen is one mechanism modulating fibril diameter and is at least partially responsible for the regulation of collagen fibril formation.

  7. Posterior Corneal Characteristics of Cataract Patients with High Myopia.

    Science.gov (United States)

    Jing, Qinghe; Tang, Yating; Qian, Dongjin; Lu, Yi; Jiang, Yongxiang

    2016-01-01

    To evaluate the characteristics of the posterior corneal surface in patients with high myopia before cataract surgery. We performed a cross-sectional study at the Eye and ENT Hospital of Fudan University, Shanghai, China. Corneal astigmatism and axial length were measured with a rotating Scheimpflug camera (Pentacam) and partial coherence interferometry (IOLMaster) in a high-myopia study group of 167 eyes (axial length ≥ 26 mm) and a control group of 150 eyes (axial length > 20 mm and myopia group than in the control group. There was no significant difference in posterior corneal astigmatism between the high-myopia study group and the control group. In the study group, the mean posterior corneal astigmatism (range 0 - -0.9 diopters) was -0.29 diopters (D) ± 0.17 standard deviations (SD). The steep corneal meridian was aligned vertically (60°-120°) in 87.43% of eyes for the posterior corneal surface, and did not change with increasing age. There was a significant correlation (r = 0.235, p = 0.002) between posterior corneal astigmatism and anterior corneal astigmatism, especially when the anterior corneal surface showed with-the-rule (WTR) astigmatism (r = 0.452, p = 0.000). There was a weak negative correlation between posterior corneal astigmatism and age (r = -0.15, p = 0.053) in the high-myopia group. Compared with total corneal astigmatism values, the anterior corneal measurements alone overestimated WTR astigmatism by a mean of 0.27 ± 0.18 D in 68.75% of eyes, underestimated against-the-rule (ATR) astigmatism by a mean of 0.41 ± 0.28 D in 88.89% of eyes, and underestimated oblique astigmatism by a mean of 0.24 ± 0.13 D in 63.64% of eyes. Posterior corneal astigmatism decreased with age and remained as ATR astigmatism in most cases of high myopia. There was a significant correlation between posterior corneal astigmatism and anterior corneal astigmatism when anterior corneal astigmatism was WTR. If posterior corneal astigmatism is not accounted for when

  8. Partial-thickness corneal tissue restoration after a chemical burn

    Directory of Open Access Journals (Sweden)

    Galan A

    2016-04-01

    Full Text Available Alessandro Galan, Anton Giulio Catania, Giuseppe Lo Giudice San Paolo Ophthalmic Center, San Antonio Hospital, Padova, Italy Purpose: We describe a case of full-thickness corneal restoration after an acute corneal burn with an acid agent. Methods: A 32-year-old male reported painful discomfort, redness, photophobia, and a decrease in visual acuity in the left eye after a unilateral burn with an acid agent. Slit-lamp examination revealed massive corneal melting involving necrotic sequestrum of the entire corneal surface. Surgical approach was carried out in order to preserve residual ocular tissues. Results: Extensive corneal–conjunctival layer curettage of the necrotic tissue was performed showing perfectly clear undamaged deep lamellar corneal layers. The patient underwent multilayered amniotic membrane transplantation and total capsular–conjunctival flap in order to preserve ocular tissue from further melting or corneal perforation. A complete and spontaneous “restitutio ad integrum” of the corneal layers was shown during the follow-up. The cornea was perfectly clear with restored normal anatomical architecture. Conclusion: In this case, a spontaneous full-thickness corneal tissue restoration occurred after an acute chemical burn. Studies about the mechanisms whereby different cells interact and replicate within the stroma may unveil the biology behind corneal regeneration and transparency. Keywords: amniotic membrane, chemical burn, corneal healing

  9. Corneal biomechanical features in patients with ankylosing spondylitis.

    Science.gov (United States)

    Cabuk, Kubra Serefoglu; Üstün, Emine Isil; Atalay, Kursat; Kirgiz, Ahmet; Aydin, Rukiye

    2017-01-01

    To evaluate the corneal biomechanical features and central corneal thickness in ankylosing spondylitis patients and to evaluate correlations of these parameters with disease activity. The study included 51 patients diagnosed with ankylosing spondylitis (mean age, 40.80 ± 13.15 years; range, 18-72 years) and 34 age- and sex-matched healthy controls (mean age, 42.00 ± 12.32 years; range, 18-60 years). All underwent a complete ophthalmological and physical examination, including visual acuity testing and biomicroscopic anterior and posterior segment examinations. Corneal hysteresis, corneal resistance factor, Goldmann-correlated intraocular pressure, and corneal compensated intraocular pressure were evaluated with an ocular response analyzer, and the central corneal thickness was measured with Sirius® corneal tomography. The Bath Ankylosing Spondylitis Disease Activity Index, Functional Index, and Metrology Index scores were recorded. In the ankylosing spondylitis patients, the mean disease duration was 7.73 ± 6.05 (range, 1-30) years. There was no statistically significant difference between the patients and controls in the corneal biomechanical features. The Goldmann-correlated intraocular pressure and corneal compensated intraocular pressure both showed positive correlations with age (p=0.003 and p=0.001, res-pectively). There was a negative correlation between corneal hysteresis and disease duration (p=0.002), and between central corneal thickness and the Bath Ankylosing Spondylitis Metrology Index score (p=0.003). This study demonstrated a significant negative correlation between corneal hysteresis and disease duration in ankylosing spondylitis patients. Furthermore, the central corneal thickness value decreased with an increase in Bath Ankylosing Spondylitis Metrology Index score, which may result in an underestimate of intraocular pressure readings and thus an inaccurate risk assessment of glaucoma.

  10. Corneal Astigmatism Stability in Descemet Membrane Endothelial Keratoplasty for Fuchs Corneal Dystrophy.

    Science.gov (United States)

    Yokogawa, Hideaki; Sanchez, P James; Mayko, Zachary M; Straiko, Michael D; Terry, Mark A

    2016-07-01

    To calculate the magnitude and angle of the shift in corneal astigmatism associated with Descemet membrane endothelial keratoplasty (DMEK) surgery to determine the feasibility of concurrent astigmatism correction at the time of DMEK triple procedures. Retrospective study. Forty-seven eyes that previously underwent the DMEK procedure for Fuchs endothelial corneal dystrophy and that had more than 1.0 diopter (D) of front corneal astigmatism preoperatively were identified. All DMEK surgeries used a clear corneal temporal incision of 3.2 mm. Surgically induced astigmatism (SIA) was evaluated 6 months postsurgery with vector analysis using Scheimpflug image reading. We did not find a difference between pre- and postoperative magnitude of front astigmatism (P = 0.88; paired t test). The magnitude of the SIA front surface was 0.77 ± 0.63 D (range, 0.10-3.14 D). The centroid vector of the SIA front surface was 0.14 at 89.3°. A hyperopic corneal power shift was noted in both the front surface by 0.26 ± 0.74 D (range, 0.45-3.05 D) (P = 0.018; paired t test) and back surface by 0.56 ± 0.55 D (range, 0.25-2.40 D) (P astigmatism that is a with-the-rule shift associated with a temporal clear corneal incision. The stability of these data from preop to postop supports the plausibility of incorporating astigmatism correction with the cautious use of toric intraocular lenses for patients with Fuchs corneal dystrophy and cataract.

  11. Long-Term Topical Ganciclovir and Corticosteroids Preserve Corneal Endothelial Function in Cytomegalovirus Corneal Endotheliitis.

    Science.gov (United States)

    Fan, Nai-Wen; Chung, Yu-Chien; Liu, Yao-Chung; Liu, Catherine Jui-Ling; Kuo, Yih-Shiuan; Lin, Pei-Yu

    2016-05-01

    To report the long-term outcomes of topical ganciclovir (GCV) and corticosteroids as a maintenance therapy for cytomegalovirus (CMV) corneal endotheliitis. This retrospective study included 10 eyes of 9 patients diagnosed with CMV corneal endotheliitis with a minimum 1-year follow-up at a tertiary referral hospital between 2008 and 2014. CMV corneal endotheliitis was defined by corneal edema associated with typical keratic precipitates (KPs) and a positive CMV polymerase chain reaction from aqueous humor taps. Patients receiving long-term topical 0.5% GCV and topical corticosteroids without discontinuation were included. The final corneal condition and endothelial cell density (ECD) were reported. The mean age was 45.6 ± 11.7 years. The mean follow-up duration was 48 ± 25 months. All patients exhibited typical coin-shaped and/or linear KPs. A significant resolution of corneal edema and decreased KPs were achieved within 1 month in all patients after initiating topical 0.5% GCV every 2 hours and topical corticosteroids twice a day. The dose frequency was gradually tapered to GCV 4 times and corticosteroids once or twice a day as a maintenance therapy. All 10 eyes had a clear graft or corneas at the end of this study. The mean ECD was 1630 ± 699 cells per millimeter square before treatment and 1776 ± 834 cells per millimeter square at the end of the study period. Topical 0.5% GCV and corticosteroids as a maintenance regimen without interruption effectively preserved long-term corneal endothelial function.

  12. Relationship between Corneal Guttae and Quality of Vision in Patients with Mild Fuchs' Endothelial Corneal Dystrophy.

    Science.gov (United States)

    Watanabe, Shinya; Oie, Yoshinori; Fujimoto, Hisataka; Soma, Takeshi; Koh, Shizuka; Tsujikawa, Motokazu; Maeda, Naoyuki; Nishida, Kohji

    2015-10-01

    To investigate the effect of the severity of corneal guttae on quality of vision (QOV) in patients with mild Fuchs' endothelial corneal dystrophy (FECD). Cross-sectional study. Twenty-three eyes of 14 patients with mild FECD without corneal edema on slit-lamp examination (5 pseudophakic eyes and 18 phakic eyes with mild lens opacity; grade 1.0-2.0 nuclear opalescence, grade 1.0-2.0 nuclear color, grade 1.0 cortical cataract, and grade 1.0 posterior subcapsular cataract on the Lens Opacities Classification System, version III). The area ratio of the corneal guttae (ARCG) in the endothelial cells was measured by multifocal specular microscopy. The QOV parameters, that is, corrected distance visual acuity (CDVA), letter contrast sensitivity (LCS), and intraocular straylight, also were measured. The correlations were assessed between the ARCG and QOV parameters and between the straylight and CDVA and LCS. The ARCG, logarithm of the minimum angle of resolution CDVA, LCS, and straylight. Univariate analysis showed that the ARCG was correlated significantly with the CDVA, LCS, and straylight (R(2) = 0.41, P = 0.001; R(2) = 0.55, P = 0.001; and R(2) = 0.39, P = 0.002, respectively). Univariate analysis also showed that straylight was correlated significantly with the CDVA and LCS (R(2) = 0.47, P = 0.001 and R(2) = 0.41, P = 0.001, respectively). Corneal guttae without edema caused the QOV to deteriorate in eyes with FECD. Patients with higher straylight had worse CDVA or LCS. Intraocular forward light scatter caused by corneal guttae may result in visual disturbances. Quantification of corneal guttae can be useful to evaluate the effect of guttae on the QOV and determine the surgical indications of endothelial keratoplasty for eyes with mild FECD. Copyright © 2015 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

  13. Femoral head diameter in the Malaysian population.

    Science.gov (United States)

    Lee, Chee Kean; Kwan, Mun Keong; Merican, Azhar Mahmood; Ng, Wuey Min; Saw, Lim Beng; Teh, Kok Kheng; Krishnan, Manoharan; Ramiah, Ramanathan

    2014-08-01

    Hip arthroplasty is commonly performed worldwide. The objective of this study was to determine the diameter of the femoral head in the Malaysian population in relation to gender and race (i.e. among Malay, Chinese and Indian patients). This was a retrospective cross-sectional study performed between January 1995 and December 2006, evaluating the femoral head diameters of all patients aged 50 years and above who underwent hemiarthroplasty at two major hospitals in Malaysia. A total of 945 femoral heads (663 women, 282 men) were evaluated. The mean age of the patients in our cohort was 75.2 ± 9.4 (range 50-101) years. The mean femoral head diameter (with intact articular cartilage) was 44.9 ± 3.2 (range 38-54) mm. In our study, men had a significantly larger mean femoral head diameter than women (47.7 ± 2.8 mm vs. 43.7 ± 2.4 mm; p Chinese ethnicity were also found to have significantly larger femoral head diameters, when compared among the three races studied (p Malaysians have a mean femoral head diameter of 44.9 ± 3.2 mm. Among our patients, Chinese patients had a significantly larger femoral head size than Malay and Indian patients. We also found that, in our cohort, men had significantly larger femoral head diameters than women.

  14. Central and Peripheral Corneal Power Change in Myopic Orthokeratology and Its Relationship With 2-Year Axial Length Change.

    Science.gov (United States)

    Zhong, Yuanyuan; Chen, Zhi; Xue, Feng; Miao, Huamao; Zhou, Xingtao

    2015-07-01

    We assessed the relationship between axial length (AL) change and corneal refractive power change induced by orthokeratology (ortho-k) contact lens wear. A total of 88 myopic children aged 7 to 12 years were fitted with ortho-k lenses for overnight wear. Axial length was measured before enrollment and every 6 months after initiation of lens wear up to 24 months. Corneal apical refractive power and the mean power of each concentric ring from 0.5 to 7.2 mm in diameter at 0.1-mm intervals were measured using the Pentacam HR, and compared before and after 3 months of ortho-k lens wear. Summed corneal power change (SCPC) was defined as the sum of relative corneal power change within the central 7.2-mm diameter corneal region. Age, baseline spherical equivalent refractive error (SERE), and SCPC were tested against 2-year AL growth in a stepwise multiple linear regression model. Of the 88 myopic children who were successfully fitted with ortho-k lenses, 64 completed the 2-year follow-up period. These completed test subjects experienced a mean axial growth of 0.37 ± 0.27 mm. Spherical equivalent refractive error and corneal apical refractive power decreased from baseline values of -2.88 ± 0.96 diopters (D) and 43.47 ± 1.03 D to -0.20 ± 0.85 D and 40.61 ± 1.23 D, respectively, after 3 months of lens wear. The mean SCPC was 10.84 ± 5.28 D · mm after 3 months. Axial elongation was significantly correlated with SCPC (standardized β = -0.573, P SCPC and baseline age to predict axial elongation was acceptable (adjusted R2 = 0.56) and statistically significant (F2,61 = 41.09, P < 0.001). Axial elongation in children undergoing ortho-k therapy is negatively correlated with the age of the wearer and summed corneal power change from the central to the mid-peripheral cornea. We speculate that axial elongation is influenced by the extent to which the retinal defocus profile is altered with ortho-k lens wear. (http://www.chictr.org number, ChiCTR-TNRC-11001210.).

  15. Effect of fourth-generation fluoroquinolones on the healing rate of corneal erosions in an animal model.

    Science.gov (United States)

    Barequet, Irina S; Habot-Wilner, Zohar; Lavinsky, Fabio; Ziv, Hana; Belkin, Michael; Rosner, Mordechai

    2007-06-01

    To compare the rate of epithelial healing of corneal erosion in an animal model with 2 commercial formulations of fourth-generation fluoroquinolones: 0.3% gatifloxacin and 0.5% moxifloxacin. Corneal erosions, 6 mm in diameter, were created in 28 rabbit eyes. The rabbits were randomized to receive topical gatifloxacin, moxifloxacin, or nonpreserved saline. Drops were administered every 15 minutes for 1 hour, then hourly for 3 hours, and then 4 times daily until the erosion reepithelialized. Eyes were examined with fluorescein drops and photographed every 12 hours with a cobalt blue-filtered light. When reepithelialization was observed, the rabbits were euthanized, and their eyes were enucleated for histopathologic evaluation. Reepithelialization of the corneal erosions was fastest in the saline-treated eyes (57.3 +/- 8 hours), followed by moxifloxacin (62.7 +/- 11.7 hours) and gatifloxacin (66 +/- 8.5 hours). These differences in the time to closure of the erosions among the 3 groups were not statistically significant. Although significant differences were found among the healing progression curves when all 3 groups were compared (P = 0.042), the difference between the 2 antibiotic-treated groups was not significant. Only slight differences in epithelial healing rates were found between the gatifloxacin-, moxifloxacin-, and saline-treated groups, suggesting that the 2 fluoroquinolones may have an equivalent role as prophylactic treatment of trauma- or surgery-induced corneal erosions.

  16. Interferometer for measuring dynamic corneal topography

    Science.gov (United States)

    Micali, Jason Daniel

    The cornea is the anterior most surface of the eye and plays a critical role in vision. A thin fluid layer, the tear film, coats the outer surface of the cornea and serves to protect, nourish, and lubricate the cornea. At the same time, the tear film is responsible for creating a smooth continuous surface where the majority of refraction takes place in the eye. A significant component of vision quality is determined by the shape of the cornea and stability of the tear film. It is desirable to possess an instrument that can measure the corneal shape and tear film surface with the same accuracy and resolution that is currently performed on common optical elements. A dual interferometer system for measuring the dynamic corneal topography is designed, built, and verified. The completed system is validated by testing on human subjects. The system consists of two co-aligned polarization splitting Twyman-Green interferometers designed to measure phase instantaneously. The primary interferometer measures the surface of the tear film while the secondary interferometer simultaneously tracks the absolute position of the cornea. Eye motion, ocular variation, and a dynamic tear film surface will result in a non-null configuration of the surface with respect to the interferometer system. A non-null test results in significant interferometer induced errors that add to the measured phase. New algorithms are developed to recover the absolute surface topography of the tear film and corneal surface from the simultaneous interferometer measurements. The results are high-resolution and high-accuracy surface topography measurements of the in vivo cornea that are captured at standard camera frame rates. This dissertation will cover the development and construction of an interferometer system for measuring the dynamic corneal topography of the human eye. The discussion starts with the completion of an interferometer for measuring the tear film. The tear film interferometer is part of an

  17. Corneal Graft Rejection: Incidence and Risk Factors

    Directory of Open Access Journals (Sweden)

    Alireza Baradaran-Rafii

    2008-12-01

    Full Text Available

    PURPOSE: To determine the incidence and risk factors of late corneal graft rejection after penetrating keratoplasty (PKP. METHODS: Records of all patients who had undergone PKP from 2002 to 2004 without immunosuppressive therapy other than systemic steroids and with at least one year of follow up were reviewed. The role of possible risk factors such as demographic factors, other host factors, donor factors, indications for PKP as well as type of rejection were evaluated. RESULTS: During the study period, 295 PKPs were performed on 286 patients (176 male, 110 female. Mean age at the time of keratoplasty was 38±20 (range, 40 days to 90 years and mean follow up period was 20±10 (range 12-43 months. Graft rejection occurred in 94 eyes (31.8% at an average of 7.3±6 months (range, 20 days to 39 months after PKP. The most common type of rejection was endothelial (20.7%. Corneal vascularization, regrafting, anterior synechiae, irritating sutures, active inflammation, additional anterior segment procedures, history of trauma, uncontrolled glaucoma, prior graft rejection, recurrence of herpetic infection and eccentric grafting increased the rate of rejection. Patient age, donor size and bilateral transplantation had no significant influence on graft rejection. CONCLUSION: Significant risk factors for corneal graft rejection include

  18. Corneal biomechanical properties distribution in myopic population

    Directory of Open Access Journals (Sweden)

    Mohammad Mirzaei

    2014-03-01

    Full Text Available AIM: To evaluate distribution of corneal biomechanical measurements in normal myopia and myopic-astigmatism population.METHODS:One hundred and eighty eyes with myopia and myopic-astigmatism candidated for laser refractive surgery were included in this study. Complete examination of anterior and posterior segments, manifest refraction spherical equivalent(MRSE, Orbscan and Zywave were performed preoperatively. Ocular response analyzer(ORAwas used to measure corneal hysteresis(CH, corneal resistance factor(CRF, Goldmann-correlated intraocular pressure(IOPgand corneal compensated IOP(IOPcc. Distribution of all corneal biomechanical properties and correlation between these parameters and MRSE, age and sex were determined. Statistical analysis was performed using SPSS 17 software and a P-Value less than 0.05 was considered significant. RESULTS: Mean age was 28.20±6.78 years. Mean MRSE was -4.21±1.19D. Mean CH, CRF, IOPg and IOPcc was 10.00±1.28mmHg, 10.17±1.45mmHg, 15.71±2.67mmHg and 16.68±2.41mmHg respectively. 28.4% of all myopic population had CH about 10mmHg, and 71% had CH, 9mmHg up to 11mmHg. CRF in 25.9% of myopic population was 10mmHg, and in 48.7% was 9mmHg up to 11mmHg. There was very poor positive correlation between MRSE& CH(Rs=0.001, P=0.71and MRSE& CRF(Rs=0.01, P=0.18.CONCLUSION: Our study demonstrated the distribution of corneal biomechanical properties(CH, CRF, IOPg, IOPccin normal myopia and myopic-astigmatism population in Iran, and confirmed that, there was no statistically significant correlation between CH, CRF and MRSE, age and sex but there was significant correlation between IOPg, IOPcc and formerly mentioned parameters.

  19. Corona sign: manifestation of peripheral corneal epithelial edema as a possible marker of the progression of corneal endothelial dysfunction.

    Science.gov (United States)

    Inoue, Tomoyuki; Hara, Yuko; Kobayashi, Takeshi; Zheng, Xiaodong; Suzuki, Takashi; Shiraishi, Atsushi; Ohashi, Yuichi

    2016-09-01

    To describe a characteristic form of the corona sign and its clinical relevance to the degree of corneal endothelial decompensation and investigate the underlying mechanism using a rabbit model. These observational cases include 31 patients undergoing penetrating keratoplasty (PKP) and 15 patients undergoing Descemet stripping automated endothelial keratoplasty (DSAEK) with special attention to the circumferentially developed corneal epithelial edema. We also conducted a laboratory observation of horizontal water flow in the rabbit cornea. We consistently observed the corona sign at the superior periphery during the initial stage of corneal endothelial decompensation after PKP. With progressive corneal endothelial cellular loss, the epithelial edema gradually expanded circumferentially in the periphery. The endothelial cellular density associated with the corona sign significantly (P corona sign compared with a superior corona sign. After DSAEK, however, the corneal epithelial edema subsided from the center but persisted peripherally as a corona sign in all cases. By 3 months postoperatively, the epithelial edema was confined to the superior periphery along with uneventful corneal endothelial healing. Rabbit experiments showed that total corneal endothelial decompensation decreased the horizontal intracorneal water migration (Inoue-Ohashi phenomenon) in the corneal periphery and induced peripheral corneal edema. The slit-lamp microscopic findings of the corona-like epithelial edema in the peripheral cornea are associated with the stage of corneal endothelial function. To support this, the developmental mechanism of the corona sign was demonstrated experimentally.

  20. Ciliary neurotrophic factor promotes the activation of corneal epithelial stem/progenitor cells and accelerates corneal epithelial wound healing.

    Science.gov (United States)

    Zhou, Qingjun; Chen, Peng; Di, Guohu; Zhang, Yangyang; Wang, Yao; Qi, Xia; Duan, Haoyun; Xie, Lixin

    2015-05-01

    Ciliary neurotrophic factor (CNTF), a well-known neuroprotective cytokine, has been found to play an important role in neurogenesis and functional regulations of neural stem cells. As one of the most innervated tissue, however, the role of CNTF in cornea epithelium remains unclear. This study was to explore the roles and mechanisms of CNTF in the activation of corneal epithelial stem/progenitor cells and wound healing of both normal and diabetic mouse corneal epithelium. In mice subjecting to mechanical removal of corneal epithelium, the corneal epithelial stem/progenitor cell activation and wound healing were promoted by exogenous CNTF application, while delayed by CNTF neutralizing antibody. In cultured corneal epithelial stem/progenitor cells, CNTF enhanced the colony-forming efficiency, stimulated the mitogenic proliferation, and upregulated the expression levels of corneal epithelial stem/progenitor cell-associated transcription factors. Furthermore, the promotion of CNTF on the corneal epithelial stem/progenitor cell activation and wound healing was mediated by the activation of STAT3. Moreover, in diabetic mice, the content of CNTF in corneal epithelium decreased significantly when compared with that of normal mice, and the supplement of CNTF promoted the diabetic corneal epithelial wound healing, accompanied with the advanced activation of corneal epithelial stem/progenitor cells and the regeneration of corneal nerve fibers. Thus, the capability of expanding corneal epithelial stem/progenitor cells and promoting corneal epithelial wound healing and nerve regeneration indicates the potential application of CNTF in ameliorating limbal stem cell deficiency and treating diabetic keratopathy. © 2014 AlphaMed Press.

  1. Combined corneal allotransplantation and vitreoretinal surgery using an Eckardt temporary keratoprosthesis: analysis for factors determining corneal allograft survival.

    Science.gov (United States)

    Lee, Dae Seung; Heo, Jang Won; Choi, Hyuk Jin; Kim, Mee Kum; Wee, Won Ryang; Oh, Joo Youn

    2014-01-01

    To evaluate the outcome of corneal allotransplantation in combined penetrating keratoplasty and vitreoretinal surgery using a temporary keratoprosthesis, and to determine the factors affecting corneal allograft survival. We reviewed the medical charts of eleven patients who had undergone combined corneal allotransplantation and pars plana vitrectomy using an Eckardt temporary keratoprosthesis, for the treatment of corneal opacification and vitreoretinal disease. The survival rates of the corneal grafts were assessed, and patient demographics, the diagnosis of corneal and retinal disease, the preoperative ocular characteristics, and surgical methods were compared between the group with graft survival and that with graft failure. The causes of corneal opacification were corneal laceration (four eyes), infectious keratitis (four eyes), atopic keratitis (one eye), rejected corneal graft (one eye), and uveitis-related bullous keratopathy (one eye). The preoperative diagnoses included endophthalmitis (six eyes), posterior uveitis (one eye), vitreous opacity or hemorrhage (two eyes), and rhegmatogenous retinal detachment (two eyes). The survival rate of the corneal allografts was 27.3% (3/11 eyes). The mean survival time was 391 days during the mean follow-up period of 687 days. The retinal surgery was successful in 81.8% (9/11 eyes) of cases. The presence of active inflammation in the cornea at the time of surgery was significantly correlated with graft rejection (P=0.004). Other factors, including age, the presence of glaucoma, type of corneal and retinal disease, or type of retinal surgery, such as silicone oil injection and gas tamponade, had no significant correlation with graft rejection. Combined corneal allotransplantation and pars plana vitrectomy using a temporary keratoprosthesis allowed for successful surgical intervention in vitreoretinal disease. However, only 27.3% of corneal allografts survived, depending on the presence of active inflammation in the

  2. Effects of aberrant Pax6 gene dosage on mouse corneal pathophysiology and corneal epithelial homeostasis.

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    Richard L Mort

    Full Text Available Altered dosage of the transcription factor PAX6 causes multiple human eye pathophysiologies. PAX6⁺/⁻ heterozygotes suffer from aniridia and aniridia-related keratopathy (ARK, a corneal deterioration that probably involves a limbal epithelial stem cell (LESC deficiency. Heterozygous Pax6(+/Sey-Neu (Pax6⁺/⁻ mice recapitulate the human disease and are a good model of ARK. Corneal pathologies also occur in other mouse Pax6 mutants and in PAX77(Tg/- transgenics, which over-express Pax6 and model human PAX6 duplication.We used electron microscopy to investigate ocular defects in Pax6⁺/⁻ heterozygotes (low Pax6 levels and PAX77(Tg/- transgenics (high Pax6 levels. As well as the well-documented epithelial defects, aberrant Pax6 dosage had profound effects on the corneal stroma and endothelium in both genotypes, including cellular vacuolation, similar to that reported for human macular corneal dystrophy. We used mosaic expression of an X-linked LacZ transgene in X-inactivation mosaic female (XLacZ(Tg/- mice to investigate corneal epithelial maintenance by LESC clones in Pax6⁺/⁻ and PAX77(Tg/- mosaic mice. PAX77(Tg/- mosaics, over-expressing Pax6, produced normal corneal epithelial radial striped patterns (despite other corneal defects, suggesting that centripetal cell movement was unaffected. Moderately disrupted patterns in Pax6⁺/⁻ mosaics were corrected by introducing the PAX77 transgene (in Pax6⁺/⁻, PAX77(Tg/- mosaics. Pax6(Leca4/+, XLacZ(Tg/- mosaic mice (heterozygous for the Pax6(Leca4 missense mutation showed more severely disrupted mosaic patterns. Corrected corneal epithelial stripe numbers (an indirect estimate of active LESC clone numbers declined with age (between 15 and 30 weeks in wild-type XLacZ(Tg/- mosaics. In contrast, corrected stripe numbers were already low at 15 weeks in Pax6⁺/⁻ and PAX77(Tg/- mosaic corneas, suggesting Pax6 under- and over-expression both affect LESC clones.Pax6⁺/⁻ and PAX77(Tg

  3. Keratoconus-integrated characterization considering anterior corneal aberrations, internal astigmatism, and corneal biomechanics.

    Science.gov (United States)

    Alió, Jorge L; Piñero, David P; Alesón, Alicia; Teus, Miguel A; Barraquer, Rafael I; Murta, Joaquim; Maldonado, Miguel J; Castro de Luna, Gracia; Gutiérrez, Ramón; Villa, César; Uceda-Montanes, Antonio

    2011-03-01

    To evaluate the clinical features of keratoconus taking into consideration anterior corneal aberrations, internal astigmatism, and corneal biomechanical properties and to define a new grading system based on visual limitation. Vissum Corporation, Alicante, Spain. Retrospective case series. This multicenter study comprised consecutive keratoconic eyes with no previous ocular surgery or active ocular disease. Visual, refractive, corneal topography, and pachymetry outcomes were analyzed. Internal astigmatism was calculated by vectorial analysis. Corneal aberrations and corneal biomechanics characterized by the Ocular Response Analyzer were evaluated in some eyes. Correlations between clinical data and a linear multiple regression analysis for characterizing the relationship between visual limitation and objective clinical data were performed. This study comprised 776 eyes of 507 patients (age range 11 to 79 years) The mean keratometry (K) correlated significantly with logMAR corrected distance visual acuity (CDVA) (r = 0.591, Paberrations between 4 groups differentiated by visual limitation (Pcorneas and allowed development of a new grading system for this condition. Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  4. Corneal Biomechanical Assessment Using Corneal Visualization Scheimpflug Technology in Keratoconic and Normal Eyes

    Directory of Open Access Journals (Sweden)

    Lei Tian

    2014-01-01

    Full Text Available Purpose. To compare the corneal biomechanical properties of keratoconic patients and age-matched controls using corneal visualization Scheimpflug technology (Corvis ST. Methods. Sixty keratoconic eyes from 47 keratoconus patients and 60 normal eyes from 60 controls were enrolled in this prospective study. Tomography and biomechanical parameters of all eyes were obtained with the Pentacam and Corvis ST, respectively. Intraocular pressure was measured using a Goldmann applanation tonometer. Results. The tomography and biomechanical parameters of the keratoconic corneas were significantly different from those of the normal corneas except for the anterior chamber angle, first applanation length, the highest concavity time, and peak distance. The deformation amplitude was the best predictive parameter (area under the curve: 0.882, with a sensitivity of 81.7%, although there was a significant overlap between keratoconic and normal corneas that ranged from 1.0 to 1.4 mm. In both the keratoconus and control groups, the deformation amplitude was negatively correlated with intraocular pressure, central corneal thickness, and corneal volume at 3 and 5 mm. Conclusions. Corvis ST offers an alternative method for measuring corneal biomechanical properties. The possibility of classifying keratoconus based on deformation amplitude deserves clinical attention.

  5. Effect of DATS on experimental corneal neovascularization induced by corneal suture in rats cornea

    Directory of Open Access Journals (Sweden)

    Xiao-Jun Zhou

    2017-11-01

    Full Text Available AIM: To study the effect of diallyl trisulfide(DATSon experimental corneal neovascularization(CNVin rats induced by corneal suture and detect the expression of vascular endothelial growth factor(VEGFand p-AKT in rats cornea. METHODS: The rat model of corneal neovascularization(CNVwas induced by corneal suture. Rats were randomly divided into Group A: physiological saline control group containing DMSO(10 rats; Group B: 25μmol/L DATS treatment group(10 rats; Group C: 50μmol/L DATS treatment group(10 rats; Group D: 100μmol/L DATS treatment group(10 rats; Group E: 200μmol/L DATS treatment group(10 rats. The occurrence and development of CNV were observed by slit-lamp microscope at 7d after suture, and the area of CNV were calculated.Two weeks later, HE staining was used to observe the pathological organization form of each cornea, and RT-PCR and Western blot were used to detect the expression of VEGF mRNA and protein expression of VEGF and p-AKT between each groups. RESULTS: The blood vessel area of Group C, D and E was compared with that of Group A, the difference was statistically significant(PPPCONCLUSION: DATS can inhibit corneal neovascularization of the rats induced by suture. Its mechanism may be associated with suppression of VEGF secretion, down-regulation of VEGF and inactivation of p-AKT.

  6. Corneal Shape, Volume, and Interocular Symmetry: Parameters to Optimize the Design of Biosynthetic Corneal Substitutes.

    Science.gov (United States)

    Durr, Georges M; Auvinet, Edouard; Ong, Jeb; Meunier, Jean; Brunette, Isabelle

    2015-07-01

    To characterize the three-dimensional (3D) shape, volume distribution, and mirror symmetry of the right and left corneas at the scale of a large population, based on the integrated analysis of 3D corneal shape average maps and topography parameters. A total of 7670 Orbscan II corneal topographies from 3835 consenting subjects with no history of ocular disease were studied. Average topography maps were created using the right and left corneal topographies of all subjects. To quantify symmetry, left eye topographies were flipped horizontally into "right eye" topographies and statistics maps were generated, including difference and intraclass correlation coefficient (ICC) maps. The standard deviation of the anterior and posterior average elevation maps in the 3-mm radius central zone of the right and left corneas ranged within ± 8 μm and ± 44 μm, respectively. The ICC maps showed almost perfect interocular agreement for anterior elevation, posterior elevation, and pachymetry (all ICCs > 0.96). All studied shape parameters also showed excellent agreement (ICCs ≥ 0.80). Mirror symmetry was not affected by age, sex, or spherical equivalent. We also showed that this horizontal reflection (flip) of the right and left corneal shapes could not be replaced by a simple rotation. These results indicate that in normal eyes, the anterior elevation, posterior elevation, and pachymetry of the right and left corneas show remarkable symmetry. This comprehensive analysis was achieved with the purpose of guiding the development of future biosynthetic corneal substitutes.

  7. Relationship between corneal biomechanical properties, central corneal thickness, and intraocular pressure across the spectrum of glaucoma.

    Science.gov (United States)

    Kaushik, Sushmita; Pandav, Surinder Singh; Banger, Anupam; Aggarwal, Kanika; Gupta, Amod

    2012-05-01

    To evaluate corneal biomechanical properties across the glaucoma spectrum and study the relationship between these measurements and intraocular pressure measured by Goldmann applanation tonometry (GAT-IOP) and central corneal thickness (CCT). Prospective cross-sectional study. Tertiary-care teaching institute. A total of 323 eyes of 323 participants (71 normal, 101 glaucoma suspect [GS], 38 ocular hypertension [OHT], 59 primary angle-closure disease [PACD], 36 primary open-angle glaucoma [POAG], and 18 normal-tension glaucoma [NTG]) who had received no ophthalmic treatment. Corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated IOP (IOPcc), and Goldmann-correlated IOP (IOPg) measured by the Ocular Response Analyzer (ORA). GAT-IOP and CCT recorded in all subjects. Regression analysis used to determine the relationship between GAT-IOP, CCT, age, CRF, and CH. Bland-Altman plots used to assess agreement between IOP measured by GAT and the ORA (IOPg). CH measurements were significantly less in POAG and NTG compared to normal subjects (P = .034 and P = .030 respectively), regardless of the IOP. The CRF was significantly less in NTG and maximum in POAG and OHT. Regression analysis with CH as dependant variable showed significant association with GAT-IOP and CRF (P glaucoma. CRF appears to influence GAT-IOP measurements more than simple geometric thickness measured by CCT. However, IOP measurements from the ORA are not interchangeable with, and are unlikely to replace, Goldmann applanation tonometry at the present time. Copyright © 2012 Elsevier Inc. All rights reserved.

  8. Spontaneous corneal melting during pregnancy: a case report.

    Science.gov (United States)

    Oh, Joo Youn; Kim, Mee Kum; Park, Joong Shin; Wee, Won Ryang

    2009-05-26

    Biomechanical changes in the cornea during pregnancy might lead to pathological conditions such as corneal perforation or melting. A 33-year-old Asian female who underwent penetrating keratoplasty in both eyes developed corneal melting in the right eye and marginal keratitis in the left eye in her fifth month of pregnancy. Marginal keratitis in the left eye immediately subsided with topical steroid therapy. However, spontaneous corneal melting progressed in the right eye, despite oral steroid therapy and amniotic membrane transplantation. We performed tectonic penetrating keratoplasty and corneoscleral grafting in the right eye. We advise caution in the ophthalmologic care of pregnant patients who have preexisting corneal thinning disorders or who have undergone multiple corneal surgeries, because physiologic changes during pregnancy might contribute to corneal changes leading to spontaneous melting especially in patients with compromised cornea.

  9. Systemic immunomodulatory strategies in high-risk corneal transplantation

    Directory of Open Access Journals (Sweden)

    Tulio B Abud

    2017-01-01

    Full Text Available The cornea is the most commonly transplanted tissue in the body. Although corneal grafts generally have high success rates, transplantation onto inflamed and vascularized host beds, or so-called high-risk corneal transplantation, has a high rate of graft rejection. The management of this high-risk corneal transplantation is challenging and involves numerous measures. One of the key measures to prevent graft rejection in these cases is the use of systemic immunosuppressive agents. In this article, we will review the systemic immunosuppressive agents most commonly used for high-risk corneal transplantation, which include corticosteroids, cysclosporine A, tacrolimus, mycophenolate mofetil, and rapamycin. Benefits, risks, and published data on the use of these medications for high-risk corneal transplantation will be detailed. We will also summarize novel immunoregulatory approaches that may be used to prevent graft rejection in high-risk corneal transplantation.

  10. [Congenital corneal anesthesia related to trigeminal anesthesia: case report].

    Science.gov (United States)

    Netto, Miguel José Calix; Della Giustina, Eduardo; Ramos, Gabriel Zatti; Mocellin, Sheila Paula; Sousa, Luciene Barbosa de

    2005-01-01

    Corneal anesthesia is a rare condition, therefore its diagnosis is frequently impaired or it is not noticed during the anterior segment examination. Case report of a 18-year-old patient referred to our Corneal and External Disease Department who complained of dry eye symptoms and with a suspicion of Sjögren's syndrome. She had amblyopia of the right eye, consequence of corneal leucoma over the visual axis secondary to a fingernail traumatism inflicted by herself in childhood. On the ophthalmologic examination corneal sensitivity was absent in both eyes. Severe dry eye and breakup time less than four seconds. Diagnosis of congenital corneal anesthesia was established, secondary to trigeminal anesthesia found on neurological evaluation of facial sensitivity. She also showed sudden movements of the chin which evidenced sensorial pathology of the trigeminal nerve. The general ophthalmologist and specially anterior segment specialists must perform tests for corneal sensitivity during the routine eye examination.

  11. Recurrence of keratoconus in two corneal grafts after penetrating keratoplasty.

    Science.gov (United States)

    Unal, Mustafa; Yücel, Iclal; Akar, Yusuf; Akkoyunlu, Gökhan; Ustünel, Ismail; Gültekin, Ismail

    2007-04-01

    To report the recurrence of postkeratoplasty keratoconus in 2 corneal grafts harvested from the same donor. Interventional case reports. A 21-year-old-man with advanced keratoconus in his right eye and a 28-year-old-woman with corneal leucoma in her right eye underwent penetrating keratoplasty with 2 grafts coming from the same donor. Approximately 1.5 years after grafting, corneal irregularity and astigmatism caused visual acuities of the patients to decrease to counting fingers. Clinical findings and corneal topography suggested the recurrence of keratoconus. A repeat keratoplasty was performed in both patients. Histopathology of the excised corneal grafts was consistent with keratoconus and confirmed the preoperative diagnosis. Recurrence of keratoconus in a patient who had no preexisting keratoconus and in 2 corneal grafts coming from the same donor suggested transmission of the disorder from the donor instead of true recurrence.

  12. Quantitative evaluation of the corneal endothelium in the mouse after grafting

    OpenAIRE

    Plskova, J; Kuffova, L; Filipec, M; Holan, V; Forrester, J V

    2004-01-01

    Background/aim: Corneal graft survival depends critically on the quality of the endothelium. In this study the authors aimed to evaluate corneal endothelium in mice at different times after transplantation and to correlate endothelial integrity with corneal graft survival.

  13. Appendiceal diameter: CT versus sonographic measurements

    Energy Technology Data Exchange (ETDEWEB)

    Orscheln, Emily S. [University of Cincinnati Medical Center, Department of Radiology, Cincinnati, OH (United States); Trout, Andrew T. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, Cincinnati, OH (United States)

    2016-03-15

    Ultrasound and CT are the dominant imaging modalities for assessment of suspected pediatric appendicitis, and the most commonly applied diagnostic criterion for both modalities is appendiceal diameter. The classically described cut-off diameter for the diagnosis of appendicitis is 6 mm when using either imaging modality. To demonstrate the fallacy of using the same cut-off diameter for both CT and US in the diagnosis of appendicitis. We conducted a retrospective review of patients younger than 18 years who underwent both US and CT of the appendix within 24 h. The shortest transverse dimension of the appendix was measured at the level of the proximal, mid and distal appendix on US and CT images. We compared mean absolute difference in appendiceal diameter between US and CT, using the paired t-test. We reviewed exams of 155 children (58.7% female) with a mean age of 11.3 ± 4.2 years; 38 of the children (24.5%) were diagnosed with appendicitis. The average time interval between US and CT was 7.0 ± 5.4 h. Mean appendiceal diameter measured by CT was significantly larger than that measured by US in cases without appendicitis (5.3 ± 1.0 mm vs. 4.7 ± 1.1 mm, P < 0.0001) and in cases with appendicitis (8.3 ± 2.2 mm vs. 7.0 ± 2.0 mm, P < 0.0001). Mean absolute diameter difference at any location along the appendix was 1.3-1.4 mm in normal appendices and 2 mm in cases of appendicitis. Measured appendiceal diameter differs between US and CT by 1-2 mm, calling into question use of the same diameter cut-off (6 mm) for both modalities for the diagnosis of appendicitis. (orig.)

  14. Age and Aortic Diameters in Pilots.

    Science.gov (United States)

    Akın, Ahmet; Ozturk, Cengiz; Aparci, Mustafa; Cakmak, Tolga; Metin, Suleyman; Balta, Sevket; Sen, Ahmet

    2015-12-01

    Pilots are exposed to various physical and hemodynamic stresses during flight. Aortic dilatation may be one of the important consequences of flight-related stress. In this study, we evaluated whether or not variation in aortic diameter was associated with the type of aircraft and the age of pilots. Medical records of 87 jet aircraft pilots (JP) (mean age = 30.0 ± 7.0 years) and 65 non-jet aircraft pilots (NJP) (mean age = 32.63 ± 5.7) were reviewed. Echocardiographic diameters of the aortic sinus (AoS) and ascending aorta (AoAsc) were measured using standard echo probe positions. Aortic diameters were not statistically different between JP and NJP. Regression analysis revealed that the diameters of the AoS (R = 0.484, R(2) = 0.234, p age in the JP group. Whereas, there was not any relationship found between age and the diameters of the AoS and AoAsc in the NJP group. Jet pilots had aortic enlargement as they became older in contrast to the NJP group. Although the aortic diameters were not within the critical ranges in the JP group, these results could suggest that flight-related stresses might result in acute aortic syndromes in the long term. Reprint & Copyright © 2015 Association of Military Surgeons of the U.S.

  15. Experimental assessment of human corneal hysteresis.

    Science.gov (United States)

    Elsheikh, Ahmed; Wang, Defu; Rama, Paolo; Campanelli, Marino; Garway-Heath, David

    2008-03-01

    Hysteresis is a viscoelastic property characterized by the difference in behavior under loading and unloading. The aim of the study was to determine corneal hysteresis using experimental means. Twenty-nine human corneas with 50-95 year age were subjected to cycles of pressure loading and unloading. Two pressure application rates were adopted to approximate static and dynamic loading conditions. The behavior under both loading and unloading was found to stiffen with increased age. The unloading behavior appeared to be largely independent of the pressure level at which unloading started. The difference between the behavior patterns under loading and unloading was quantified and used as a measure of corneal hysteresis. The hysteresis area was significantly larger with faster loading and with decreased age. The trend for hysteresis to decrease with age is in agreement with previous clinical observations. Hysteresis was also found to increase with faster pressure application.

  16. Corneal biomechanics in asymmetrical normal-tension glaucoma

    Directory of Open Access Journals (Sweden)

    Helmy H

    2016-03-01

    Full Text Available Hazem Helmy,1 Mahmoud Leila,2 Ahmed Atef Zaki3 1Department of Glaucoma and Optic Nerve Diseases, 2Retina Department, 3Corneal Diseases Department, Research Institute of Ophthalmology, Cairo, Egypt Purpose: We aimed to assess corneal biomechanics using the ocular response analyzer in patients with normal-tension glaucoma (NTG, and to evaluate the relationship between corneal biomechanics and visual field loss. Methods: This was a prospective observational case series including patients with bilateral asymmetric NTG. For all patients, corneal hysteresis (CH, corneal resistance factor (CRF, CH - CRF difference, and central corneal thickness values were matched against the mean deviation (MD of the visual field and the cup/disc ratio. For paired-eye comparison in each patient, both eyes were categorized into a better-eyes group and a worse-eyes group according to lower and higher corneal-compensated intraocular pressure readings, respectively. Statistical analysis was carried out with the independent-samples Student’s t-test, and the level of statistical significance was set at 0.05. Correlation was assessed using Pearson’s correlation coefficient. Results: The study included 240 eyes of 120 patients. CH was inversely proportional to the MD in the visual field (P=0.01. CRF in both eyes was inversely proportional to the MD of the visual field (P=0.01. CH - CRF difference was directly proportional to the MD of the visual field (P=0.01. For paired-eye comparison, lower corneal-compensated intraocular pressure was associated with higher CH, higher CRF, smaller cup/disc ratio, and less deterioration of MD of visual field. Conclusion: CH, CRF, and CH - CRF are more powerful predictors of NTG progression than central corneal thickness. Keywords: corneal-compensated intraocular pressure, corneal hysteresis, corneal resistance factor

  17. Corneal decompensation after intraocular ophthalmic surgery--Missouri, 1998.

    Science.gov (United States)

    1998-04-24

    During January 8-14, 1998, six of eight patients undergoing elective intraocular surgery at a Veterans Affairs medical center (VAMC) in St. Louis, Missouri, developed corneal endothelial decompensation (corneal edema and opacification) instruments sterilized by the Abtox Plazlyte system (Abtox, Inc., Chicago, Illinois). This report summarizes the results of the investigation of these cases and indicates that using the Abtox Plazlyte system to sterilize opthalmologic surgical equipment led to corneal decompensation.

  18. Corneal Biomechanical Properties in Patients With Arcus Senilis.

    Science.gov (United States)

    Ayhan, Ziya; Ozturk, Taylan; Kaya, Mahmut; Arikan, Gul; Gunenc, Uzeyir

    2016-07-01

    To compare the corneal biomechanical properties and intraocular pressure (IOP) levels in patients with and without arcus senilis (AS). Ocular response analyzer measurements were performed on the right eyes of 37 patients with AS (group 1) and 37 control eyes (group 2). Corneal hysteresis, corneal resistance factor, Goldmann-correlated IOP, and corneal compensated IOP were recorded with Ocular response analyzer. Spherical equivalent value of the refractive errors, axial length, central corneal thickness, and IOP measured with Goldmann applanation tonometer were noted for each study eyes. Statistical analyses were performed with Student t, Kruskal-Wallis, and Pearson correlation tests. Mean age was 67.6 ± 9.8 years in group 1 and 65.3 ± 8.1 years in group 2 (P = 0.308). Mean corneal hysteresis and corneal resistance factor readings were 9.8 ± 0.9 versus 10.6 ± 0.8 (P corneal compensated IOP and Goldmann-correlated IOP values were found as 16.1 ± 3.3 mm Hg versus 15.8 ± 2.6 mm Hg (P = 0.719) and 15.1 ± 3.3 mm Hg versus 15.0 ± 2.6 mm Hg (P = 0.912) in groups 1 and 2, respectively. There was no statistical difference in IOP measured with Goldmann applanation tonometer, central corneal thickness, spherical equivalent value of the refractive error, axial length measurements, and mean keratometry readings between the 2 groups (P = 0.983, P = 0.289, P = 0.938, P = 0.886, P = 0.07, respectively). The mean corneal hysteresis and corneal resistance factor values of eyes with AS were lower when compared with the controls. This study demonstrated that AS may change the corneal biomechanical properties.

  19. The theory and art of corneal cross-linking

    OpenAIRE

    Rebecca McQuaid; Cummings, Arthur B; Michael Mrochen

    2013-01-01

    Before the discovery of corneal cross-linking (CXL), patients with keratoconus would have had to undergo corneal transplantation, or wear rigid gas permeable lenses (RGPs) that would temporarily flatten the cone, thereby improving the vision. The RGP contact lens (CL) would not however alter the corneal stability and if the keratoconus was progressive, the continued steepening of the cone would occur under the RGP CL. To date, the Siena Eye has been the largest study to investigate long term ...

  20. Effects of epiplakin-knockdown in cultured corneal epithelial cells

    OpenAIRE

    Kokado, Masahide; Okada, Yuka; Miyamoto, Takeshi; Yamanaka, Osamu; Saika, Shizuya

    2016-01-01

    Background To investigate effects of knockdown of epiplakin gene expression on the homeostasis of cultured corneal epithelial cell line. We previously reported acceleration of corneal epithelial wound healing in an epiplakin-null mouse. Methods Gene expression of epiplakin was knockdowned by employing siRNA transfection in SV40-immortalized human corneal epithelial cell line. Protein expression of E-cadherin, keratin 6 and vimentin was examined by western blotting. Cell migration and prolifer...

  1. Corneal injuries from liquid detergent pods.

    Science.gov (United States)

    Gray, Michael E; West, Constance E

    2014-10-01

    Laundry and dishwasher detergent "pods" were introduced to the United States market in 2010 and are sold by several manufacturers. They represent a high percentage of household cleaning product exposure in the United Kingdom. We present a consecutive case series of 10 children seen in a 9-month period with corneal injuries from exposure to liquid detergent pods. Copyright © 2014 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.

  2. Graft Biomechanics Following Three Corneal Transplantation Techniques

    OpenAIRE

    Sepehr Feizi; Talieh Montahai; Hamidreza Moein

    2015-01-01

    Purpose: To compare corneal biomechanical properties following three different transplantation techniques, including Descemet stripping automated endothelial keratoplasty (DSAEK), deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) in comparison to normal eyes. Methods: This cross-sectional comparative study included 118 eyes: 17 eyes of 17 patients received DSAEK, 23 eyes of 21 patients underwent DALK using Anwar's big bubble technique, and 45 eyes of 36 patients ...

  3. Biomechanics of corneal ectasia and biomechanical treatments

    OpenAIRE

    Roberts, Cynthia J.; Dupps, William J.

    2014-01-01

    Many algorithms exist for the topographic/tomographic detection of corneas at risk for post-refractive surgery ectasia. It is proposed that the reason for the difficulty to find a universal screening tool based on corneal morphologic features is that curvature, elevation, and pachymetric changes are all secondary signs of keratoconus and post-refractive surgery ectasia and that the primary abnormality is in the biomechanical properties. It is further proposed that the biomechanical modificati...

  4. Contact lens management following corneal refractive surgery.

    Science.gov (United States)

    Ward, Michael A

    2003-09-01

    Corneal refractive surgery has enjoyed considerable success and popularity in recent years; LASIK has become the surgical procedure of choice. The incidence of visually significant complications varies widely, but is inversely related to surgeon experience. Visual complaints include multifocal images, shadows, ametropias, anisometropia, night vision difficulties, decreased contrast sensitivity and loss of BCVA. Contact lenses offer an option to rehabilitate patients when visually symptomatic following refractive surgery. RGP lenses provide the best postoperative visual rehabilitation following refractive surgery.

  5. Corneal hysteresis and its relevance to glaucoma

    OpenAIRE

    Deol, Madhvi; Taylor, David A.; Radcliffe, Nathan M

    2015-01-01

    Purpose of review Glaucoma is a leading cause of irreversible blindness worldwide. It is estimated that roughly 60.5 million people had glaucoma in 2010 and that this number is increasing. Many patients continue to lose vision despite apparent disease control according to traditional risk factors. The purpose of this review is to discuss the recent findings with regard to corneal hysteresis, a variable that is thought to be associated with the risk and progression of glaucoma. Recent findings...

  6. Corneal hysteresis in patients with dry eye.

    Science.gov (United States)

    Firat, P G; Doganay, S

    2011-12-01

    To measure corneal hysteresis and intraocular pressure (IOP) in patients with dry eye and to compare with normal subjects. This cross-sectional study consists of 70 eyes of 40 patients with dry eye (group 1) and 75 eyes of 40 normal subjects (group 2). Eyes were diagnosed as dry eye or normal according to the clinical symptoms, biomicroscopical evaluation, and Schirmer test. Corneal hysteresis (CH), corneal resistance factor (CRF), and cornea-compensated intraocular pressure (IOPcc) were measured by the Ocular Response Analyser (ORA). Mean CH values were 10.56±0.25 mm Hg and 10.34±0.26 mm Hg, mean CRF values were 10.75±0.28 mm Hg and 10.70±0.28 mm Hg, mean CCT values were 542±3.20 μm and 543±3.89 μm in group 1 and group 2, respectively. There was no statistically significant difference between the groups for these three parameters. IOPcc values measured with ORA were 15.73±0.36 mm Hg in group 1 and 16.60±0.33 mm Hg in group 2, and there was no statistically significant difference between the two groups. Corneal biomechanical parameters such as CH and CRF are not influenced in dry eye. Also statistical difference was not found between the two groups according to CCT and IOPcc values.

  7. Evaluation of sex differences in corneal hysteresis.

    Science.gov (United States)

    Allam, Riham S H M; Khalil, Noha M M M

    2015-01-01

    To study sex differences in corneal biomechanical parameters in Egypt as regards to corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg), and corneal-compensated intraocular pressure (IOPcc). This is a cross-sectional observational study that includes 350 eyes of 350 normal subjects (175 men and 175 women) who were evaluated using the Reichert ocular response analyzer (ORA) to measure CH, CRF, IOPg, and IOPcc. The mean CH in men was 9.69 ± 2.05 mm Hg (range 5.7-14.6 mm Hg) and in women 10.41 ± 1.65 mm Hg (range 7-14.4 mm Hg) with a p value of 0.00038. The mean CRF in men was 9.54 ± 2.16 mm Hg (range 4.9-14.4 mm Hg) and in women was 10.37 ± 1.71 mm Hg (range 7.3-15.5 mm Hg) with a p value of 0.00008. The mean IOPg in men was 14.78 ± 4.15 mm Hg (range 7.2-26.5 mm Hg) and in women was 15.44 ± 3.3 mm Hg (range 8.6-23.7 mm Hg) with a p value of 0.09. The mean IOPcc in men was 16.2 ± 4.08 mm Hg (range 10.9-28.9 mm Hg) and in women was 15.86 ± 3.41 (range 9.7-24.2 mm Hg) with a p value of 0.4. There was a statistically significant difference between men and women in CH and CRF while IOPg and IOPcc showed no statistically significant difference (p>0.05). There is a statistically significant difference between men and women in CH and CRF, where women show higher values, while no statistically significant difference exists between the groups in IOPg or IOPcc.

  8. Intrastromal application of riboflavin for corneal crosslinking.

    Science.gov (United States)

    Seiler, Theo G; Fischinger, Isaak; Senfft, Tim; Schmidinger, Gerald; Seiler, Theo

    2014-06-10

    To experimentally evaluate the efficacy of corneal crosslinking (CXL) by injecting the photomediator riboflavin into the corneal stroma via intrastromal channels. Five groups of pig corneas, nine each, were compared regarding stress-strain relationship and UV-absorption. Group 1 had intrastromal channels floated with riboflavin 0.5%-solution followed by UVA-irradiation (3 mW/cm(2) for 30 minutes); group 2 was handled like group 1, but were irradiated with 9 mW/cm(2) for 10 minutes; group 3 was treated according to the Dresden protocol (epi-off, 9 mW/cm(2) for 10 minutes); group 4 had the identical channel system, no riboflavin but identical irradiation; group 5 with native corneas served as a control group. The intrastromal channels were created with a femtosecond laser. The stress-strain relations were measured in corneal strips using a uniaxial material tester at strains up to 12%. The UV-transmission of the corneas was measured in groups 1, 3, and 5. The stress needed for a 10% strain was significantly increased by 82% in the corneas treated with the Dresden protocol compared with native cornea (P = 0.0005). With intrastromal application of riboflavin the significant increase was 87% (P = 0.0005) in group 1 and 64% (P = 0.007) in group 2. The channel formation alone did not alter biomechanics (P = 0.923). The corneal UVA-transmission was 2.4% after intrastromal riboflavin application, 8.9% after the treatment according to the Dresden protocol, and 57.9% in native corneas. The experiments demonstrate the intrastromal application of riboflavin by means of intrastromal channels a feasible "epi-on" approach for CXL. More experimental data are needed before clinical testing. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

  9. [Mitomycin C toxicity in rabbit corneal endothelium].

    Science.gov (United States)

    Silva, Maria Rosa Bet de Moraes; Gregório, Elisa Aparecida

    2009-01-01

    To evaluate corneal endothelium alterations after applying mitomycin C to the sclera using transmission and scanning electron microscopy, correlating alterations with time, concentration, and evaluation methods. The corneal endothelium of both eyes of 32 albino rabbits was evaluated and distributed into four groups of 8. Mitomycin C was applied under a scleral flap in the right eye for 5 minutes. Mitomycin C concentrations were 0.5 mg/ml for G1 and G2 and 0.2 mg/ml for G3 and G4. Examinations were performed 15 days after application to G1 and G3, and 30 days after application to G2 and G4. Four cornea in each group were prepared for transmission electron microscopy and four for scanning electron microscopy. Left eyes of all animals were used as controls. Transmission electron microscopy showed corneal endothelium alterations in all groups: rarefied cytoplasm, dilation and fragmentation of rough endoplasmic reticulum cisternae, Golgi apparatus with cisternal dilation, reduced vacuoles, and irregularities of internal membrane more noticeable in G1 and G2. Scanning electron microscopy revealed alterations in all groups except G1: changes in the shape and size of cells and longer filopodial projections. 1 - Corneal endothelium alterations were seen at both 0.5 and 0.2 mg/ml concentrations and at 15 and 30 days after mytomicin C application; 2 - Alterations were more intense with higher mytomicin C concentration by transmission electron but not by scanning electron microscopy; 3 - The alterations correlated with time by scanning electron microscopy but not by transmission electron microscopy.

  10. RECURRENT CORNEAL EROSION SYNDROME (a review

    Directory of Open Access Journals (Sweden)

    S. V. Trufanov

    2015-01-01

    Full Text Available Recurrent corneal erosion (RCE syndrome is characterized by episodes of recurrent spontaneous epithelial defects. Main clinical symptoms (pain, redness, photophobia, lacrimation occurred at night. Corneal lesions revealed by slit lamp exam vary depending on the presence of corneal epithelium raise, epithelial microcysts or epithelial erosions, stromal infiltrates and opacities. Microtraumas, anterior corneal dystrophies, and herpesvirus give rise to RCE. Other causes or factors which increase the risk of RCE syndrome include meibomian gland dysfunction, keratoconjunctivitis sicca, diabetes, and post-LASIK conditions. Basal membrane abnormalities and instability of epithelial adhesion to stroma play a key role in RCE pathogenesis. Ultrastructural changes in RCE include abnormalities of basal epithelial cells and epithelial basal membrane, absence or deficiency of semi-desmosomes, loss of anchor fibrils. Increase in matrix metalloproteinases and collagenases which contribute to basal membrane destruction results in recurrent erosions and further development of abnormal basal membrane. The goals of RCE therapy are to reduce pain (in acute stage, to stimulate re-epithelization, and to restore «adhesion complex» of basal membrane. In most cases, RCE responds to simple conservative treatment that includes lubricants, healing agents, and eye patches. RCEs that are resistant to simple treatment, require complex approach. Non-invasive methods include long-term contact lens use, instillations of autologous serum (eye drops, injections of botulinum toxin (induces ptosis, antiviral agent use or oral intake of metalloproteinase inhibitors. Cell membrane stabilizers, i.e., antioxidants, should be included into treatment approaches as well. Antioxidant effect of Emoxipine promotes tissue reparation due to the prevention of cell membrane lipid peroxidation as well as due to its anti-hypoxic, angioprotective, and antiplatelet effects. If conservative therapy

  11. Homogeneous UVA system for corneal cross-linking treatment

    Science.gov (United States)

    Ayres Pereira, Fernando R.; Stefani, Mario A.; Otoboni, José A.; Richter, Eduardo H.; Ventura, Liliane

    2010-02-01

    The treatment of keratoconus and corneal ulcers by collagen cross-linking using ultraviolet type A irradiation, combined with photo-sensitizer Riboflavin (vitamin B2), is a promising technique. The standard protocol suggests instilling Riboflavin in the pre-scratched cornea every 5min for 30min, during the UVA irradiation of the cornea at 3mW/cm2 for 30 min. This process leads to an increase of the biomechanical strength of the cornea, stopping the progression, or sometimes, even reversing Keratoconus. The collagen cross-linking can be achieved by many methods, but the utilization of UVA light, for this purpose, is ideal because of its possibility of a homogeneous treatment leading to an equal result along the treated area. We have developed a system, to be clinically used for treatment of unhealthy corneas using the cross-linking technique, which consists of an UVA emitting delivery device controlled by a closed loop system with high homogeneity. The system is tunable and delivers 3-5 mW/cm2, at 365nm, for three spots (6mm, 8mm and 10mm in diameter). The electronics close loop presents 1% of precision, leading to an overall error, after the calibration, of less than 10% and approximately 96% of homogeneity.

  12. Graft Biomechanics Following Three Corneal Transplantation Techniques.

    Science.gov (United States)

    Feizi, Sepehr; Montahai, Talieh; Moein, Hamidreza

    2015-01-01

    To compare corneal biomechanical properties following three different transplantation techniques, including Descemet stripping automated endothelial keratoplasty (DSAEK), deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) in comparison to normal eyes. This cross-sectional comparative study included 118 eyes: 17 eyes of 17 patients received DSAEK, 23 eyes of 21 patients underwent DALK using Anwar's big bubble technique, and 45 eyes of 36 patients had PK; 33 right eyes of 33 normal subjects served as the control group. Using the ocular response analyzer (ORA, Reichert Ophthalmic Instruments, Buffalo, New York, USA), corneal hysteresis (CH) and corneal resistance factor (CRF) were measured and compared among the study groups at least 3 months after all sutures were removed. Mean patient age was 26.9 ± 5.0 years in the control group, 28.8 ± 4.2 in the PK group, 27.2 ± 6.5 in the DALK group, and 62.5 ± 16.8 in the DSAEK group (P biomechanical parameters comparable to normal subjects (9.84 ± 1.59 and 9.89 ± 1.73 mmHg, respectively). Graft biomechanical parameters after DSAEK are lower than those following PK and DALK. After PK and DALK in keratoconic eyes, these metrics are increased to normal values. These differences may have implications for interpreting intraocular pressure or planning graft refractive surgery after keratoplasty.

  13. Biomechanics of corneal ectasia and biomechanical treatments.

    Science.gov (United States)

    Roberts, Cynthia J; Dupps, William J

    2014-06-01

    Many algorithms exist for the topographic/tomographic detection of corneas at risk for post-refractive surgery ectasia. It is proposed that the reason for the difficulty in finding a universal screening tool based on corneal morphologic features is that curvature, elevation, and pachymetric changes are all secondary signs of keratoconus and post-refractive surgery ectasia and that the primary abnormality is in the biomechanical properties. It is further proposed that the biomechanical modification is focal in nature, rather than a uniform generalized weakening, and that the focal reduction in elastic modulus precipitates a cycle of biomechanical decompensation that is driven by asymmetry in the biomechanical properties. This initiates a repeating cycle of increased strain, stress redistribution, and subsequent focal steepening and thinning. Various interventions are described in terms of how this cycle of biomechanical decompensation is interrupted, such as intrastromal corneal ring segments, which redistribute the corneal stress, and collagen crosslinking, which modifies the basic structural properties. Proprietary or commercial disclosures are listed after the references. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  14. Severe Corneal Disorders Developed After Brimonidine Tartrate Ophthalmic Solution Use.

    Science.gov (United States)

    Maruyama, Yuko; Ikeda, Yoko; Yokoi, Norihiko; Mori, Kazuhiko; Kato, Hiroaki; Ueno, Morio; Kinoshita, Shigeru; Sotozono, Chie

    2017-12-01

    The primary side effects associated with 0.1% brimonidine tartrate (BT) ophthalmic solution with sodium chlorite are allergic conjunctivitis, blepharitis, and conjunctival hyperemia. However, cornea-related side effects are rare. In this study, we report 2 similar cases in which corneal neovascularization, corneal infiltration, and corneal opacity developed after BT eye-drop use. Retrospective report of 2 cases of corneal infiltration after BT eye-drop use. Case 1 involved a 78-year-old woman with follicular conjunctivitis, corneal neovascularization, and infiltration in her left eye after unilateral instillation of BT eye drops in that eye. Case 2 involved a 75-year-old woman with bilateral corneal neovascularization and infiltration after instillation of BT eye drops. In both cases, the corneal complications were deemed to be side effects of BT, so those eye drops were replaced with 0.1% fluorometholone eye drops. After replacement, blepharitis and corneal neovascularization successfully resolved; however, a layer of opacity remained across the transparent layer of the cornea in both cases. We encountered 2 cases of corneal and conjunctival complications that developed as side effects after BT eye-drop use, thus indicating that strict attention should be paid to the possibility of side effects after initiation of antiglaucoma eye-drop use.

  15. Global Survey of Corneal Transplantation and Eye Banking.

    Science.gov (United States)

    Gain, Philippe; Jullienne, Rémy; He, Zhiguo; Aldossary, Mansour; Acquart, Sophie; Cognasse, Fabrice; Thuret, Gilles

    2016-02-01

    Corneal transplantation restores visual function when visual impairment caused by a corneal disease becomes too severe. It is considered the world's most frequent type of transplantation, but, to our knowledge, there are no exhaustive data allowing measurement of supply and demand, although such data are essential in defining local, national, and global strategies to fight corneal blindness. To describe the worldwide situation of corneal transplantation supply and demand. Data were collected between August 2012 and August 2013 from a systematic review of published literature in parallel with national and international reports on corneal transplantation and eye banking. In a second step, eye bank staff and/or corneal surgeons were interviewed on their local activities. Interviews were performed during international ophthalmology or eye-banking congresses or by telephone or email. Countries' national supply/demand status was classified using a 7-grade system. Data were collected from 148 countries. Corneal transplantation and corneal procurements per capita in each country. In 2012, we identified 184,576 corneal transplants performed in 116 countries. These were procured from 283,530 corneas and stored in 742 eye banks. The top indications were Fuchs dystrophy (39% of all corneal transplants performed), a primary corneal edema mostly affecting elderly individuals; keratoconus (27%), a corneal disease that slowly deforms the cornea in young people; and sequellae of infectious keratitis (20%). The United States, with 199.10-6 corneal transplants per capita, had the highest transplantation rate, followed by Lebanon (122.10-6) and Canada (117.10-6), while the median of the 116 transplanting countries was 19.10-6. Corneas were procured in only 82 countries. Only the United States and Sri Lanka exported large numbers of donor corneas. About 53% of the world's population had no access to corneal transplantation. Our survey globally quantified the considerable shortage of

  16. Lamellar keratoplasty for the treatment of feline corneal sequestrum

    OpenAIRE

    Gonçalves, Catarina Alexandra Ventura

    2015-01-01

    Dissertação de Mestrado Integrado em Medicina Veterinária, Ciências Veterinárias O sequestro corneal felino caracteriza-se por uma lesão corneal pigmentada. Esta lesão apresenta várias tonalidades e pode afetar diferentes camadas da córnea. A fisiopatologia do sequestro não é completamente conhecida, contudo o trauma corneal é considerado um importante fator desencadeador e as raças braquicefálicas são mais frequentemente afetadas. O sequestro corneal é uma lesão dolorosa, cujo tratamento ...

  17. Preliminary studies of rabbit corneal structure using laser beams

    Science.gov (United States)

    Carstocea, Benone D.; Gafencu, Otilia L.; Apostol, Silvia; Ionita, Marcel A.; Pascu, Mihail-Lucian; Moise, N.; Popescu, Gheorghe; Roman, Miruna; Hogiu, S.

    1996-12-01

    A new method for corneal structure investigation is reported. The light reflected form rabbit cornea is recorded by a video-camera so that the images of epithelium and endothelium are obtained. Because of the great magnification factor due to the corneal curvature, the characteristics of the cells can be directly visualized. The theoretical evaluation of the optical magnification fits reasonably well the experimental results for collimated laser beams; therefore in the future it will be possible to determine with a good accuracy the corneal cell dimensions. Corneal diagnosis based on this method is discussed.

  18. Corneal collagen cross-linking (CXL) combined with refractive procedures for the treatment of corneal ectatic disorders: CXL plus.

    Science.gov (United States)

    Kymionis, George D; Grentzelos, Michael A; Portaliou, Dimitra M; Kankariya, Vardhaman P; Randleman, J Bradley

    2014-08-01

    To discuss current combined corneal collagen cross-linking (CXL) and refractive surgical techniques (herein termed "CXL plus") for the treatment of corneal ectatic disorders to improve functional visual acuity in addition to corneal stability from CXL alone. Literature review. Efficacious combined treatments with CXL include: photorefractive keratectomy, transepithelial phototherapeutic keratectomy, intrastromal corneal ring segments implantation, phakic intraocular lens implantation, and multiple combined procedures. Some uncertainty remains as to the optimal strategies for each patient. A decision tree is proposed to facilitate optimal patient management. With multiple adjuvant techniques, CXL plus is likely to benefit many patients with corneal ectatic disorders. The appropriate combined procedure will depend on multiple factors, such as refraction, corneal thickness, and degree of irregular astigmatism. Copyright 2014, SLACK Incorporated.

  19. Clinical study on human lamellar keratoplasty for fungal corneal ulcers with porcine acellular corneal stroma

    Directory of Open Access Journals (Sweden)

    Fu-Hong Liao

    2017-09-01

    Full Text Available AIM: To observe the transplantation of acellular porcine corneal stroma on the treatment of superficial keratitis by drug-resistant fungal. METHODS: We performed a retrospective analysis of 16 cases of fungal keratitis received the transplantation of acellular porcine corneal matrix from June 2015 to March 2016 with a follow-up of 6mo. We analyzed on items as postoperative visual acuity, corneal graft status, postoperative recurrence and postoperative complications. RESULTS: We observed a healing time of corneal epithelium in 7 to 10d postoperatively generally and the absence of corneal edema in 1mo, while the cornea gradually returned transparent in the 16 cases. Two cases required medication for an epithelial recovery and 3 cases received intervention for decreasing intraocular pressure to a certain level. During the follow-up we observed no cases of cornea degeneration, recurrence of infection or rejection. The vision acuity showed 1.27±0.22, 1.11±0.13, 0.79±0.22 in 1, 3 and 6mo after operation respectively. There was no statistical difference between vision in 1mo and the vision before surgery(P=0.06; while we found a statistical difference when comparing the vision of 3 and 6mo with vision before surgery(P=0.01,0.001. The vision in 6mo increased with a statistic difference to the vision at 1 and 3mo(PP=0.11. CONCLUSION: Transplantation of acellular porcine corneal matrix is a safe and efficient treatment for fungal keratitis.

  20. Corneal flap displacement and drift in LASIK: comparison of Hansatome and Automated Corneal Shaper microkeratomes.

    Science.gov (United States)

    Ufret-Vincenty, Rafael L; Jiunn-Liang Chen, Rogan; Azar, Dimitri T

    2002-11-01

    To describe and compare the displacement of corneal flaps created during laser in situ keratomileusis (LASIK) procedures performed with two different microkeratomes and analyze parameters (for example, pupil-to-hinge distance, drift during suction) that might affect the flap displacement or be influenced by flap displacement. This work was based on a cross-sectional study design. Images copied from video recordings of 206 consecutive LASIK surgeries were analyzed to determine the distance from pupil center to corneal flap hinge (pupil-to-hinge distance), the hinge size, the distance from the center of the pupil to the margins of the flap, and the positions of the suction ring before and after vacuum in corneal flaps created by the Hansatome and the Automated Corneal Shaper (ACS) microkeratomes. Accurate measurements of all these variables could be obtained in 121 eyes (Hansatome: n = 66, right eye (OD) = 27 eyes, left eye (OS) = 39 eyes; ACS: n = 55, OD = 25 eyes, OS = 30 eyes), which were included in the analysis. Formulas were derived to calculate from the measurements the magnitude and direction of the drift of the suction ring during vacuum and the final displacement of the corneal flap. The mean +/- standard deviation (SD) drift of eyes during suction with the Hansatome was 0.27 +/- 0.02 mm and with the ACS was 0.12 +/- 0.02 mm (P pupil was of equal magnitude for the two instruments (0.37 +/- 0.02 mm and 0.36 +/- 0.02 mm with the Hansatome and ACS, respectively). The drift induced by the Hansatome contributes to the horizontal component of the final decentration of the corneal flaps. This tendency for drift and the resultant decrease in pupil-to-hinge distance should be considered to minimize flap displacements during LASIK.

  1. Corneal topography parameters after superior clear corneal incision cataract surgery in arcus lipoides.

    Science.gov (United States)

    Resch, M D; Bausz, M; Nagy, Z Z; Suveges, I

    2006-01-01

    To compare changes in corneal topographic parameters after cataract surgery in eyes with different severities of arcus lipoides. Fourty eyes of 40 patients (23 women, 17 men, age 71.3+/-20.4 years, range 40 to 89 years) were studied prospectively in a consecutive, non-interventional, comparative series of cases. Eyes were classed in three groups (0 to 2) according to the assessed grade of arcus lipoides (none, 180 degrees). Corneal topography (Tomey TMS-2) was performed preoperatively and at 1 and 10 days and 1 and 3 months following cataract surgery (superior 4.0 mm clear corneal incision, no suture). Keratometric astigmatism (Dcyl), surface regularity index (SRI), surface asymmetry index (SAI), and potential visual acuity (PVA) were evaluated for the different groups and time-points, using the Kruskal-Wallis, Wilcoxon, and Mann-Whitney statistical tests. No significant preoperative difference was found in mean Dcyl, SRI, or PVA; preoperative SAI was lower in Group 1. Postoperatively Dcyl was increased at day 1 in Groups 1 and 2, and remained higher in Group 2 until month 1. At month 3 significant differences among Groups 0, 1, and 2 disappeared. The 4.0 mm superior clear corneal incision is a safe method for cataract surgery in the presence of arcus lipoides. This procedure induces greater corneal astigmatism, surface irregularity, and lower PVA in the early postoperative period in cases with arcus lipoides than in normal corneas. Concerning final results, wound healing was not affected by greater severity of arcus lipoides, although stabilization of the corneal surface tended to be slower.

  2. The relationship between diurnal variations in intraocular pressure measurements and central corneal thickness and corneal hysteresis.

    Science.gov (United States)

    Kotecha, Aachal; Crabb, David P; Spratt, Alexander; Garway-Heath, David F

    2009-09-01

    To examine the relationship between office-hour changes in IOP, measured with the Goldmann applanation tonometer (GAT) and dynamic contour tonometer (DCT), and the corneal characteristics central corneal thickness (CCT) and corneal hysteresis (CH). Sixty-two eyes of 62 untreated normal subjects and patients with untreated glaucoma had IOP measurements performed with the GAT (mm Hg) and DCT (mm Hg) over an 8-hour period at 2-hour intervals beginning at 9 AM. CCT (micrometers) was measured using a noncontact optical low-coherence reflectometry (OLCR) pachymeter, and CH (mm Hg) was measured with an ocular response analyzer (ORA). The associations between IOP measurements and corneal characteristics for each patient over the measurement period were assessed by using multilevel modeling. GAT and DCT IOP and CCT changed significantly during office hours (ANOVA; GAT: F = 19.9, P IOP measurements revealed that both CCT and CH changes were significantly associated with GAT IOP changes (GAT IOP/CCT slope, 0.04 mm Hg/microm; 95% confidence intervals [CIs], 0.02-0.06; GAT IOP/CH slope, 0.20 mm Hg/mm Hg; 95% CI, 0.01-0.39). CCT, but not CH, changes were significantly associated with DCT IOP changes (DCT IOP/CCT slope, 0.03 mm Hg/microm; 95% CI, 0.00-0.05). However, although the association between CCT and GAT IOP was relatively uniform between subjects, association between CCT and DCT IOP showed greater intersubject variability. Age had no effect on the diurnal variation of IOP measured with either device. Measured IOP and corneal characteristics covary during office hours. Changes in CCT and CH are associated with changes in GAT IOP and, less consistently, with DCT IOP. The data suggest that variations in corneal characteristics explain a small proportion of the change in IOP measurements made with the GAT during office hours.

  3. Calculating graft size and position in rotational corneal autografting: a simplified approach

    National Research Council Canada - National Science Library

    Rao, Srinivas K; Lam, Dennis S C

    2008-01-01

    In eyes with eccentric corneal opacities partially involving the pupillary area, using a rotational corneal autograft, can help restore vision without the immunological complications associated with allografts...

  4. Effects of single-segment Intacs implantation on visual acuity and corneal topographic indices of keratoconus

    Directory of Open Access Journals (Sweden)

    Kazem Amanzadeh

    2017-09-01

    Conclusion: Intacs implantation in keratoconic eyes increased visual acuity and made corneal shape less irregular. However, the improvements of visual acuity and corneal shape were not strongly correlated.

  5. The Heritability of Glaucoma-Related Traits Corneal Hysteresis, Central Corneal Thickness, Intraocular Pressure, and Choroidal Blood Flow Pulsatility

    OpenAIRE

    Ellen E Freeman; Marie-Hélène Roy-Gagnon; Denise Descovich; Hugues Massé; Lesk, Mark R.

    2013-01-01

    PURPOSE: The purpose of this work was to investigate the heritability of potential glaucoma endophenotypes. We estimated for the first time the heritability of the pulsatility of choroidal blood flow. We also sought to confirm the heritability of corneal hysteresis, central corneal thickness, and 3 ways of measuring intraocular pressure. METHODS: Measurements were performed on 96 first-degree relatives recruited from Maisonneuve-Rosemont Hospital in Montreal. Corneal hysteresis was determined...

  6. Manifestaciones corneales en las enfermedades sistémicas Corneal manifestations in systemic diseases

    OpenAIRE

    J. Zarranz-Ventura; E. De Nova; J. Moreno-Montañés

    2008-01-01

    Un gran número de enfermedades sistémicas presentan manifestaciones corneales dentro de su espectro de enfermedad. El estudio detallado de todos los cuadros que asocian patología corneal resulta inabarcable, por ello se presentan las enfermedades más prevalentes o características. Este estudio contempla las enfermedades pulmonares y conectivopatías (colagenosis, enfermedades reumatológicas y enfermedades inflamatorias idiopáticas), las enfermedades dermatológicas, cardiovasculares, hematológi...

  7. Corneal layer plate removal with Fluconazole injected corneal stroma and autologous conjunctival transplantation for keratomycosis

    Directory of Open Access Journals (Sweden)

    Li-Dong Yang

    2013-08-01

    Full Text Available AIM: To investigate the clinical effect of corneal layer plate removal with Fluconazole injected corneal stroma and autologous conjunctival transplantation for keratomycosis.METHODS: There were 168 cases suffered keratomycosis that the focus located shallow of the cornea and was not obvious to drug, who registered in our hospital from March 2005 to June 2010. In surgery we removed plate layer to cormea clear, the region was greater than focus for 0.5mm,then we injected fluconazole which is 2g/L density in corneal stroma to make the edema area greater than Removal of area for 0.5mm. At last we took pedicle conjunctival flap to cover the plant bed by continuous suture. Postoperative day use drug to drop eye and to observe that whether recurrent of the keratomycosis and how was the edema degrade, the blood supply of conjunctival graft pieces, how about the stimulating signs of the surgery eye, the vision.RESULTS: The improvement rate was 96.2% after surgery for seven days and the cure rate was 95.5% after surgery for one months. We found in 157 eyes accepted trigeminy surgery there were 6 eyes recurrence and the recurrence rate was 3.8%. The mean time of corneal stromal edema faded away was 13.4 hours. After surgery for one month there were 39 eyes(24.8%whose vision removed than preoperative, there were 91 eyes(58.0%whose vision were same as preoperative and there were 27 eyes(17.2%whose vision lower than preoperative. In these operations the loss ratio of corneal endothelium was from 0%-8%, the mean was 2.9%. The irritative symptoms postoperative were mild for 87%, moderate for 10% and severe for 3%. By this surgery the mean length of stay was 7.3 days so the mean hospitalization expenses only were 2160 RMB. Three months after surgery, 4 cases were slight corneal ectasia.CONCLUSION: This operation combined corneal layer plate removal, Fluconazole injected corneal stroma and autologous conjunctival transplantation for keratomycosis which was in

  8. The Correlation Analysis between Corneal Biomechanical Properties and the Surgically Induced Corneal High-Order Aberrations after Small Incision Lenticule Extraction and Femtosecond Laser In Situ Keratomileusis

    OpenAIRE

    Wenjing Wu; Yan Wang

    2015-01-01

    Background. To investigate the correlation between corneal biomechanics and the surgically induced corneal high-order aberrations (HOAs) after small incision lenticule extraction (SMILE) and femtosecond laser in situ keratomileusis (FS-LASIK). Methods. A total of 150 right myopic eyes that underwent SMILE or FS-LASIK surgery were included in this retrospective study, 75 eyes in each group. The corneal hysteresis (CH) and the corneal resistance factor (CRF) with the corneal HOAs of the anterio...

  9. DiameterJ: A validated open source nanofiber diameter measurement tool.

    Science.gov (United States)

    Hotaling, Nathan A; Bharti, Kapil; Kriel, Haydn; Simon, Carl G

    2015-08-01

    Despite the growing use of nanofiber scaffolds for tissue engineering applications, there is not a validated, readily available, free solution for rapid, automated analysis of nanofiber diameter from scanning electron microscope (SEM) micrographs. Thus, the goal of this study was to create a user friendly ImageJ/FIJI plugin that would analyze SEM micrographs of nanofibers to determine nanofiber diameter on a desktop computer within 60 s. Additional design goals included 1) compatibility with a variety of existing segmentation algorithms, and 2) an open source code to enable further improvement of the plugin. Using existing algorithms for centerline determination, Euclidean distance transforms and a novel pixel transformation technique, a plugin called "DiameterJ" was created for ImageJ/FIJI. The plugin was validated using 1) digital synthetic images of white lines on a black background and 2) SEM images of nominally monodispersed steel wires of known diameters. DiameterJ analyzed SEM micrographs in 20 s, produced diameters not statistically different from known values, was over 10-times closer to known diameter values than other open source software, provided hundreds of times the sampling of manual measurement, and was hundreds of times faster than manual assessment of nanofiber diameter. DiameterJ enables users to rapidly and thoroughly determine the structural features of nanofiber scaffolds and could potentially allow new insights to be formed into fiber diameter distribution and cell response. Published by Elsevier Ltd.

  10. Directed growth of diameter-tunable nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Ozturk, Birol; Talukdar, Ishan; Flanders, Bret N [Department of Physics, Oklahoma State University, 145 Physical Sciences II, Stillwater, OK 74078 (United States)

    2007-09-12

    This study characterizes a method for controlling the nanowire diameter in the directed electrochemical nanowire assembly technique, where alternating voltages applied to electrodes in simple salt solutions induce the crystallization of metallic wires. Dendritic solidification is identified as an important component of this technique. A characteristic of dendritic solidification is that the growth velocity and tip radius are anti-correlated. This relationship is exploited here to realize diameter-tunable nanowire growth. The experimental parameter that provides this control is {omega}, the frequency of the alternating voltage. Increasing {omega} effectively steepens the metal cation concentration gradient at the wire-solution interface, thereby increasing the growth velocity of the wire. For indium wires, increasing {omega} from 0.5 to 3.5 MHz increases their growth velocity from 11 to 78 {mu}m s{sup -1} and reduces their diameter from 770 to 114 nm. Gold wires exhibit diameter-tunability that ranges from 150 nm to 45 nm. Thus, it is possible to tune the wire diameter from the microscale down to the nanoscale. Moreover, this control is a consequence of non-stationary dendritic growth, which distinguishes this process from most previously studied examples of dendritic solidification.

  11. Collagen fibril diameter and leather strength.

    Science.gov (United States)

    Wells, Hannah C; Edmonds, Richard L; Kirby, Nigel; Hawley, Adrian; Mudie, Stephen T; Haverkamp, Richard G

    2013-11-27

    The main structural component of leather and skin is type I collagen in the form of strong fibrils. Strength is an important property of leather, and the way in which collagen contributes to the strength is not fully understood. Synchrotron-based small angle X-ray scattering (SAXS) is used to measure the collagen fibril diameter of leather from a range of animals, including sheep and cattle, that had a range of tear strengths. SAXS data were fit to a cylinder model. The collagen fibril diameter and tear strength were found to be correlated in bovine leather (r(2) = 0.59; P = 0.009), with stronger leather having thicker fibrils. There was no correlation between orientation index, i.e., fibril alignment, and fibril diameter for this data set. Ovine leather showed no correlation between tear strength and fibril diameter, nor was there a correlation across a selection of other animal leathers. The findings presented here suggest that there may be a different structural motif in skin compared with tendon, particularly ovine skin or leather, in which the diameter of the individual fibrils contributes less to strength than fibril alignment does.

  12. Diameter effect on critical heat flux

    Energy Technology Data Exchange (ETDEWEB)

    Tanase, A. [University of Ottawa, Department of Mechanical Engineering, Ottawa, ON (Canada)], E-mail: atana052@uottawa.ca; Cheng, S.C. [University of Ottawa, Department of Mechanical Engineering, Ottawa, ON (Canada); Groeneveld, D.C. [University of Ottawa, Department of Mechanical Engineering, Ottawa, ON (Canada); Chalk River Laboratories, Atomic Energy of Canada Ltd., Chalk River, ON (Canada); Shan, J.Q. [Department of Nuclear Engineering, Xi' an Jiaotong University (China)

    2009-02-15

    The critical heat flux look-up table (CHF LUT) is widely used to predict CHF for various applications, including design and safety analysis of nuclear reactors. Using the CHF LUT for round tubes having inside diameters different from the reference 8 mm involves conversion of CHF to 8 mm. Different authors [Becker, K.M., 1965. An Analytical and Experimental Study of Burnout Conditions in Vertical Round Ducts, Aktiebolaget Atomenergie Report AE 177, Sweden; Boltenko, E.A., et al., 1989. Effect of tube diameter on CHF at various two phase flow regimes, Report IPE-1989; Biasi, L., Clerici, G.C., Garriba, S., Sala, R., Tozzi, A., 1967. Studies on Burnout, Part 3, Energia Nucleare, vol. 14, pp. 530-536; Groeneveld, D.C., Cheng, S.C., Doan, T., 1986. AECL-UO critical heat flux look-up table. Heat Transfer Eng., 7, 46-62; Groeneveld et al., 1996; Hall, D.D., Mudawar, I., 2000. Critical heat flux for water flow in tubes - II subcooled CHF correlations. Int. J. Heat Mass Transfer, 43, 2605-2640; Wong, W.C., 1996. Effect of tube diameter on critical heat flux, MaSC dissertation, Ottawa Carleton Institute for Mechanical and Aeronautical Engineering, University of Ottawa] have proposed several types of correlations or factors to describe the diameter effect on CHF. The present work describes the derivation of new diameter correction factor and compares it with several existing prediction methods.

  13. Total domination in graphs with diameter 2

    DEFF Research Database (Denmark)

    Desormeaux, Wyatt J.; Haynes, Teresa W.; Henning, Michael A.

    2014-01-01

    The total domination number γt(G) of a graph G is the minimum cardinality of a set S of vertices, so that every vertex of G is adjacent to a vertex in S. In this article, we determine an optimal upper bound on the total domination number of a graph with diameter 2. We show that for every graph G ...... on n vertices with diameter 2, γt(G)≤1+nln(n). This bound is optimal in the sense that given any ε>0, there exist graphs G with diameter 2 of all sufficiently large even orders n such that γt(G)>(14+ε)nln(n)....

  14. Apical clearance rigid contact lenses induce corneal steepening.

    Science.gov (United States)

    Swarbrick, Helen A; Hiew, Ross; Kee, Ai Vy; Peterson, Sophia; Tahhan, Nina

    2004-06-01

    Anecdotal reports suggest that steeply fitted rigid contact lenses can induce corneal steepening and myopic shifts in refraction. This study investigated changes in corneal topography, corneal thickness, and refraction after short-term wear of apical clearance lenses. : Ten young adults participated in the study in which apical clearance lenses (Conoid, Hydron Pty. Ltd., Frenchs Forest, NSW, Australia), fitted approximately 0.3 mm steeper than the flattest keratometric reading, were worn for 4 h. A polymethyl methacrylate (PMMA) lens was worn in one eye, and a Boston XO lens (Bausch & Lomb, Rochester, NY) was worn in the other. Lenses were nonfenestrated in the first trial, and a single midperipheral fenestration was incorporated for a second trial. Corneal topography was monitored using the EyeSys topographic analysis system (EyeSys Vision, Inc., Houston, TX); central corneal thickness was quantified using ultrasonic pachometry; and refraction and anterior ocular response were also monitored. Significant central corneal edema (8.2 +/- 2.2%) was demonstrated in the PMMA lens-wearing eye only. Fenestration did not reduce the edema response. We found significant corneal steepening over a 5- to 6-mm central zone, which was more pronounced in the PMMA lens-wearing eye and was modified by lens fenestration. The curvature changes altered central corneal shape from prolate (Q = -0.06 +/- 0.10) to oblate (Q = -0.26 +/- 0.31). A slight myopic shift in refraction (-0.38 +/- 0.60 D) was found with the PMMA lenses only. : Apical clearance lenses induce corneal steepening after short-term wear. Although corneal molding is implicated as the primary factor driving the shape change, corneal edema and postlens tear film pressures can modify this response.

  15. [Reduction of astigmatism by 4mm long sutureless corneal cataract incision (stretch incision) with phacoemulsification and 5mm PMMA lens implantation].

    Science.gov (United States)

    Müller-Jensen, K; Schüler, M

    1998-06-01

    Refractive cataract surgery using corneal incisions is aiming at neutralization of preoperative astigmatism. 61 patients with preoperative astigmatism of 2.25 +/- 0.98 were included in the treatment. A self-sealing corneal tunnel incision measuring 4.0 to 4.1 mm in external diameter and 6.5 to 7.0 mm in internal diameter (stretch incision) was performed on the steeper axis. After capsulorhexis and phacoemulsification a 5 mm PMMA lens was implanted without suturing. Keratometry and corneal topography were performed preoperatively, 3 days and 1 year respectively following surgery. The statistical analysis was based on the Wilcoxon signed ranks test. Surgical induced astigmatism (IA) following superior incisions in cases of astigmatism with the rule (n = 29) amounted to 1.93 +/- 0.97, while lateral incisions in cases of astigmatism against the rule (n = 29) led to an IA of 1.35 +/- 0.73. Axial shifts by more than 30 degrees were 23% following superior incisions and 17%, after lateral incisions. We observed. astigmatic reduction of 1.3 D after superior incisions and 0.7 D following lateral incisions. By 4 mm corneal cataract incisions on the steeper axis a high preoperative astigmatism can be reduced significantly without additional keratotomies.

  16. Long-term comparison of corneal aberration changes after laser in situ keratomileusis: mechanical microkeratome versus femtosecond laser flap creation.

    Science.gov (United States)

    Muñoz, Gonzalo; Albarrán-Diego, César; Ferrer-Blasco, Teresa; García-Lázaro, Santiago; Cerviño-Expósito, Alejandro

    2010-11-01

    To compute and compare visual acuity, refractive outcomes, and anterior corneal aberration changes after myopic laser in situ keratomileusis (LASIK) with flap creation by a mechanical microkeratome and by a femtosecond laser. Private practice refractive surgery center, Valencia, Spain. Comparative case series. Patients were assigned to have LASIK flap creation with a mechanical microkeratome (Carriazo-Barraquer) or a femtosecond laser (IntraLase). The Visx S2 excimer laser was used for myopic ablation in all cases. Main outcome measures included uncorrected and corrected distance visual acuities and the defocus equivalent. Higher-order aberrations (HOAs) were computed from the anterior corneal surface measured with topography for 4.0 mm and 6.0 mm pupil diameters before and 48 months after surgery. The study evaluated 50 patients (98 eyes). The root mean square of HOAs increased postoperatively by a factor of approximately 1.9 in both groups and with both pupil diameters. There were no statistically significant differences between the 2 groups in the increase in anterior corneal aberrations, mean postoperative visual acuity, or residual refraction. All visual and optical performance metrics remained stable throughout the 4-year follow-up. There were no complications with flap creation and no postoperative complications. The increase in anterior corneal aberrations after myopic LASIK was similar after mechanical microkeratome and femtosecond laser flap creation. Visual acuity, refraction, and the optical quality of the cornea after LASIK remained stable through 4 years postoperatively in both groups. Copyright © 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  17. [Effect of adjustment of corneal running sutures on cylindrical refraction after perforating keratoplasty].

    Science.gov (United States)

    Urminský, J; Rozsíval, P; Lorencová, V; Jirásková, N

    2004-04-01

    Authors refer about the effect of adjusting (adjustment of the suture tension) of the running corneal suture on the final cylindrical refraction in patients who underwent penetrating keratoplasty due to keratoconus. In our article we evaluate two groups of patients. The group I consists 76 patients (76 eyes) who regularly visited our department of ophthalmology. There were 52.6% of females and 47.4% of males. The average age at the time of surgery was 33.5 +/- 5.2 years (range, 18-52 years). In this group of patients, the adjusting was performed during the surgery. In the group II 35 patients (40 eyes) underwent the adjusting procedure of the running corneal suture in the early postoperative period. There were 19 (54.0%) women and 16 (46.0%) men. The average age of the whole group at the time of surgery was 34.6 +/- 3.8 years (range, 18-50 years). The indication to carry out the adjusting was topographically verified astigmatism of more then 3.5 cylindrical diopters (D cyl). The purpose of this study was to find the ultimate surgery technique to get not only the clearness and good healing of the corneal graft, but first of all to prevent extensive ametropia already during the surgery. In the early stage after the surgery we are trying to reduce emerged refractive error and to get faster recovery of good visual acuity of the operated eye. In the sense of the least final postoperative astigmatism, the best results we have reached in cases where the donor corneal graft was 0.25 mm larger in diameter and the suture was adjusted during the surgery using light circles according to Serdarevic. In this group of patients the average final cylindrical refractive error after the surgery was 2.00 +/- 0.81 D cyl. When adjusting the corneal suture in postoperative period, the mean final refractive error decreased of about 3.09 +/- 1.62 D cyl.

  18. Comparison of corneal sensitivity, tear function and corneal staining following laser in situ keratomileusis with two femtosecond laser platforms

    Directory of Open Access Journals (Sweden)

    Petznick A

    2013-03-01

    Full Text Available Andrea Petznick,1 Annabel Chew,2 Reece C Hall,2 Cordelia ML Chan,2 Mohamad Rosman,1,2 Donald Tan,1–3 Louis Tong,1–4 Jodhbir S Mehta1–31Singapore Eye Research Institute, Singapore; 2Singapore National Eye Centre, Singapore; 3Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; 4Duke-NUS Graduate Medical School, SingaporePurpose: To evaluate longitudinal changes in corneal sensitivity, tear function, and corneal staining in patients who underwent laser in situ keratomileusis (LASIK using two different femtosecond lasers.Methods: In a prospective, randomized clinical trial, contralateral eyes of 45 patients underwent flap creation by either VisuMax or IntraLase™ femtosecond laser. Corneal sensitivity, tear break up time (TBUT, Schirmer’s test, and corneal fluorescein staining were assessed preoperatively and at 1 week, 1 month, and 3 months postoperatively.Results: There were no statistical differences in any clinical outcome measure between the two femtosecond lasers (P > 0.05, although there was a trend towards slightly lower reductions for corneal sensitivity and TBUT in VisuMax-operated eyes. Overall, corneal sensitivity was significantly reduced at 1 week (P 0.05.Conclusion: This study showed that changes in corneal sensitivity, tear function, and corneal staining were statistically similar in LASIK using VisuMax and IntraLase femtosecond lasers for flap creation. However, the trend towards faster recovery of corneal sensitivity and TBUT observed in VisuMax-operated eyes may be attributable to improved technical specifications.Keywords: femtosecond laser, corneal sensitivity, tear film break-up time, Schirmer’s, corneal staining

  19. Variations in corneal biomechanical parameters and central corneal thickness during the menstrual cycle.

    Science.gov (United States)

    Goldich, Yakov; Barkana, Yaniv; Pras, Eran; Fish, Alexander; Mandel, Yossi; Hirsh, Ami; Tsur, Nir; Morad, Yair; Avni, Isaac; Zadok, David

    2011-08-01

    To assess variations in the biomechanical properties and central corneal thickness (CCT) throughout the female menstrual cycle. Department of Ophthalmology, Assaf Harofeh Medical Center, Zerifin Israel. Case series. Young healthy women were prospectively recruited. Every participant was assessed at the beginning of the menstrual cycle, at ovulation, and at the end of the cycle. At every time point, corneal hysteresis (CH) and the corneal resistance factor (CRF) were measured with the Ocular Response Analyzer and the CCT was measured with an ultrasonic pachymeter. Twenty-two eyes of 22 women (mean age 19.5 years ± 1.5 [SD]) were included. The CH was statistically significantly decreased at ovulation (10.1 mm Hg) compared with the beginning (11.1 mm Hg, Pcornea was thinnest at the beginning (535 μm) and statistically significantly thicker at ovulation (542 μm, Pbiomechanical parameters significantly varied during the menstrual cycle. The CH and CRF were temporarily decreased at ovulation. The cornea was thinnest at the beginning and thicker at ovulation and at the end of the cycle. Such corneal changes may be important to consider during screening of candidates for laser refractive surgery. Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  20. A human corneal equivalent constructed from SV40-immortalised corneal cell lines.

    Science.gov (United States)

    Zorn-Kruppa, Michaela; Tykhonova, Svitlana; Belge, Gazanfer; Bednarz, Jürgen; Diehl, Horst A; Engelke, Maria

    2005-02-01

    Within the last decade, extensive research in the field of tissue and organ engineering has focused on the development of in vitro models of the cornea. The use of organotypic, three-dimensional corneal equivalents has several advantages over simple monolayer cultures. The aim of this study was to develop a corneal equivalent model composed of the same cell types as in the natural human tissue, but by using immortalised cell lines to ensure reproducibility and to minimise product variation. We report our success in the establishment of an SV40-immortalised human corneal keratocyte cell line (designated HCK). A collagen matrix, built up with these cells, displayed the morphological characteristics of the human stromal tissue and served as a biomatrix for the immortalised human corneal epithelial and endothelial cells. Histological cross-sections of the whole-cornea equivalents resemble human corneas in tissue structure. This organotypic in vitro model may serve as a research tool for the ophthalmic science community, as well as a model system for testing for eye irritancy and drug efficacy.

  1. [Analysis on corneal deformation and corneal biomechanical changes after small incision lenticule extraction].

    Science.gov (United States)

    Huang, Y L; Wang, Y; Dou, R; Jin, S B; Liu, L J; Li, H; Wei, P H

    2017-01-11

    Objective: To investigate biomechanical effects of central corneal thickness (CCT), and to explore the possible safe range for the tissue removal and percentage of tissue ablation (PTA) of small incision lenticule extraction (SMILE). Methods: Clinical observational study. One hundred and eighty-seven cases (365 eyes) undergoing SMILE surgery were enrolled. Corneal hysteresis (CH) and corneal resistance factor (CRF) were measured before and after surgery by the ocular response analyzer (ORA). Linear regression of CH, CRF and CCT, and percentage of tissue ablation were calculated. The fifth order polynomial functions provided the closest fit to the data of ΔCH, ΔCRF and the thickness of tissue removal. Results: CH and CRF decreased by 20.7% and 33.0%, respectively, after SMILE, and statistically significant differences were found between preoperative and postoperative values (PCorneal thickness has an effect on the corneal biomechanical properties, which decrease with the increase of tissue removal. It seems that the tissue removal of less than 140 μm and the PTA of less than 25% are safer in SMILE, and further investigations are needed. (Chin J Ophthalmol, 2017, 53:11-17).

  2. In Vivo Corneal Biomechanical Properties with Corneal Visualization Scheimpflug Technology in Chinese Population.

    Science.gov (United States)

    Wu, Ying; Tian, Lei; Huang, Yi-Fei

    2016-01-01

    Purpose. To determine the repeatability of recalculated corneal visualization Scheimpflug technology (CorVis ST) parameters and to study the variation of biomechanical properties and their association with demographic and ocular characteristics. Methods. A total of 783 healthy subjects were included in this study. Comprehensive ophthalmological examinations were conducted. The repeatability of the recalculated biomechanical parameters with 90 subjects was assessed by the coefficient of variation (CV) and intraclass correlation coefficient (ICC). Univariate and multivariate linear regression models were used to identify demographic and ocular factors. Results. The repeatability of the central corneal thickness (CCT), deformation amplitude (DA), and first/second applanation time (A1/A2-time) exhibited excellent repeatability (CV% ≤ 3.312% and ICC ≥ 0.929 for all measurements). The velocity in/out (V in/out), highest concavity- (HC-) radius, peak distance (PD), and DA showed a normal distribution. Univariate linear regression showed a statistically significant correlation between V in, V out, DA, PD, and HC-radius and IOP, CCT, and corneal volume, respectively. Multivariate analysis showed that IOP and CCT were negatively correlated with V in, DA, and PD, while there was a positive correlation between V out and HC-radius. Conclusion. The ICCs of the recalculated parameters, CCT, DA, A1-time, and A2-time, exhibited excellent repeatability. IOP, CCT, and corneal volume significantly influenced the biomechanical properties of the eye.

  3. In Vivo Corneal Biomechanical Properties with Corneal Visualization Scheimpflug Technology in Chinese Population

    Directory of Open Access Journals (Sweden)

    Ying Wu

    2016-01-01

    Full Text Available Purpose. To determine the repeatability of recalculated corneal visualization Scheimpflug technology (CorVis ST parameters and to study the variation of biomechanical properties and their association with demographic and ocular characteristics. Methods. A total of 783 healthy subjects were included in this study. Comprehensive ophthalmological examinations were conducted. The repeatability of the recalculated biomechanical parameters with 90 subjects was assessed by the coefficient of variation (CV and intraclass correlation coefficient (ICC. Univariate and multivariate linear regression models were used to identify demographic and ocular factors. Results. The repeatability of the central corneal thickness (CCT, deformation amplitude (DA, and first/second applanation time (A1/A2-time exhibited excellent repeatability (CV% ≤ 3.312% and ICC ≥ 0.929 for all measurements. The velocity in/out (Vin/out, highest concavity- (HC- radius, peak distance (PD, and DA showed a normal distribution. Univariate linear regression showed a statistically significant correlation between Vin, Vout, DA, PD, and HC-radius and IOP, CCT, and corneal volume, respectively. Multivariate analysis showed that IOP and CCT were negatively correlated with Vin, DA, and PD, while there was a positive correlation between Vout and HC-radius. Conclusion. The ICCs of the recalculated parameters, CCT, DA, A1-time, and A2-time, exhibited excellent repeatability. IOP, CCT, and corneal volume significantly influenced the biomechanical properties of the eye.

  4. Customized toric intraocular lens implantation for correction of extreme corneal astigmatism due to corneal scarring

    Directory of Open Access Journals (Sweden)

    R Bassily

    2010-03-01

    Full Text Available R Bassily, J LuckOphthalmology Department, Royal United Hospital, Combe Park, Bath, UKAbstract: A 76-year-old woman presented with decreased visual function due to cataract formation. Twenty-five years prior she developed right sided corneal ulceration that left her with 10.8 diopters (D of irregular astigmatism at 71.8° (steep axis. Her uncorrected visual acuity was 6/24 and could only ever wear a balanced lens due to the high cylindrical error. Cataract surgery was planned with a custom designed toric intraocular lens (IOL with +16.0 D sphere inserted via a wound at the steep axis of corneal astigmatism. Postoperative refraction was -0.75/+1.50 × 177° with a visual acuity of 6/9 that has remained unchanged at six-week follow-up with no IOL rotation. This case demonstrates the value of high power toric IOLs for the correction of pathological corneal astigmatism.Keywords: intraocular lens, corneal ulceration, visual acuity, scarring

  5. Corneal Sensitivity as a Potential Marker of Diabetic Neuropathy.

    Science.gov (United States)

    Sitompul, Ratna

    2017-04-01

    Diabetes mellitus (DM) is a complex and chronic metabolic disorder leading to many complications. One of the most common complications of DM is diabetic neuropathy. There are many studies exploring corneal sensitivity as a potential marker of diabetic neuropathy. This review aims to explore association between corneal sensitivity and diabetic neuropathy. In diabetic neuropathy, corneal sensitivity is impaired due to low level of corneal nerve trophic factors, impaired sensory nerve fibers, and lost communication of dendtritic cell. In diabetic patients, this condition can be assessed by several techniques, such as Cochet Bonnet aesthesiometry, non-contact corneal aesthesiometry, and confocal microscopy. Few promising therapeutic targets for impaired corneal sensitivity include stem cell and growth factor therapy that can be used to prevent complication in patient with diabetic neurotrophic keratopathy. Impaired corneal sensitivity serve as a potential marker of diabetic neuropathy. Doctors, opthalmologists and internists, should anticipate the possibility of observing the following changes in diabetic patients with neuropathy by using corneal sensitivity assessment test.

  6. Cytokine mRNA expression during experimental corneal allograft rejection

    NARCIS (Netherlands)

    Torres, P. F.; de Vos, A. F.; van der Gaag, R.; Martins, B.; Kijlstra, A.

    1996-01-01

    Allograft rejection is the main cause of corneal graft failure. T lymphocytes and macrophages have been implied to be involved in corneal rejection, but little is known about the molecular mechanism in this process. In this study, cytokine mRNA expression in the cornea was analysed during

  7. Applications and advantages of corneal crosslinking for treatment of keratoconus

    NARCIS (Netherlands)

    Soeters, N.

    2015-01-01

    Keratoconus is a corneal disorder in which the cornea becomes cone-shaped due to stromal thinning and corneal weakening. It mainly affects young individuals and although the prevalence is low (1:2000), the impact on quality of life is high. Despite much effort, still no cure has been found for

  8. Does corneal hysteresis correlate with endothelial cell density?

    Science.gov (United States)

    Akova-Budak, Berna; Kıvanç, Sertaç Argun

    2015-05-21

    Our aim was to determine if there is a correlation between corneal biomechanical properties, endothelial cell count, and corneal pachymetry in healthy corneas. Ninety-two eyes of all subjects underwent complete ocular examination, including intraocular pressure measurement by Goldmann applanation tonometer, objective refraction, and slit-lamp biomicroscopy. Topographic measurements and corneal pachymetry were performed using a Scheimpflug-based (Pentacam, Oculus, Germany) corneal topographer. Corneal hysteresis (CH) and corneal resistance factor (CRF) were measured with an Ocular Response Analyzer (ORA, Reichert Ophthalmic Instruments, Buffalo, NY). Endothelial cell count measurement was done using a specular microscope (CellChek, Konan, USA). Right eye values of the subjects were taken for the study. The mean CH was 11.5±1.7 mmHg and the mean CRF was 11.2±1.4 mmHg. Mean intraocular pressure was 15.3±2.3 mmHg. The mean endothelial cell count was 2754±205 cells/mm2. No correlation was found between biomechanical properties of cornea and endothelial cell count. There was a significant positive correlation between CH, CRF, and corneal thickness (pcorneal biomechanical properties significantly correlated with corneal thickness. We found no correlation between CH and CRF with the endothelial cell density in normal subjects.

  9. The relationship between CPAP usage and corneal thickness.

    Directory of Open Access Journals (Sweden)

    Ethem Gelir

    Full Text Available The purpose of this study was to determine whether there is a correlation between CPAP usage and corneal thickness in patients with sleep disordered breathing. Full-night polysomnography (PSG recordings were collected. Ten patients had undergone PSG recordings with continuous positive airway pressure (CPAP, and seven patients had undergone PSG recordings without CPAP. We measured corneal thickness by ultrasonic pachymeter before sleep and ten minutes after waking. We also measured visual acuity with a routine ophthalmologic eye chart before and after sleep. We asked patients to fill out a post-sleep questionnaire to get their subjective opinions. In the without-CPAP group, corneal thickness increased significantly during sleep in both eyes (left, p = 0.0025; right, p0.05 for both left and right cornea. There was no significant difference in visual acuity tests (p>0.05 for both left and right eye between the two groups. According to our results, there is a significant increase in corneal thickness in the without-CPAP group. Our data show that a low percentage of Rapid Eye Movement (REM sleep may cause an increase in corneal thickness, which can indicate poor corneal oxygenation. In fact, many sleep-disordered breathing (SDB patients have low REM. Since a contact lens may cause low corneal oxygenation, SDB patients with contact lenses should be monitored carefully for their corneal thickness.

  10. Crosslinking and corneal cryotherapy in acanthamoeba keratitis -- a histological study.

    Science.gov (United States)

    Hager, Tobias; Hasenfus, A; Stachon, T; Seitz, B; Szentmáry, N

    2016-01-01

    Acanthamoeba keratitis is rare, but difficult to treat. Penetrating keratoplasty is performed in therapy-resistant cases. Nevertheless, subsequent recurrences occur in 40 % of the cases. In addition to triple-topical therapy (polyhexamid, propamidinisoethionat, neomycin), treatment alternatives are corneal cryotherapy and/or crosslinking (CXL). The aim of our present histological study was to analyze the persistence of acanthamoebatrophozoites and cysts, the persistence of bacteria, and activation of keratocytes in corneas of acanthamoeba keratitis patients following corneal cryotherapy and/or CXL. We analyzed histologically corneal buttons (from penetrating keratoplasties) of nine patients with acanthamoeba keratitis, following corneal cryotherapy (two patients) or a combination of crosslinking and corneal cryotherapy (seven patients), using haematoxilin–eosin, periodic acid Schiff (PAS), Gram and alpha-smooth muscle actin (alpha-SMA) stainings. Acanthamoeba trophozoites persisted in three corneas after cryotherapy and CXL. Cysts persisted in one of two corneas following corneal cryotherapy and in six of seven corneas after a combination of CXL and cryotherapy. One cornea showed positive Gram staining, but there were no alpha-SMA positive keratocytes in any of the corneas. Crosslinking and corneal cryotherapy have only limited impact on killing of acanthamoeba trophozoites, cysts, or bacteria. Corneal cryotherapy and CXL did not stimulate myofibroblastic transformation of keratocytes.

  11. Prevalence of corneal ulcer among contact lens wearers in Nigeria ...

    African Journals Online (AJOL)

    Corneal Ulceration has been described as the most serious complication of contact lens wear worldwide. The incidence of corneal ulceration in contact lens wearers in Nigeria was determined retrospectively. 1759 case notes of patients who had worn contact lenses for at least one year were obtained from eye clinics in ...

  12. Minimising Corneal Scarring from the use of Harmful Traditional Eye ...

    African Journals Online (AJOL)

    Corneal scarring is the fourth largest cause of blindness globally, and a much more prominent factor in developing countries. Blindness from corneal scarring is largely a preventable phenomenon, and is capable of causing significant morbidity that can last for a lifetime. A significant proportion of these cases are caused by ...

  13. Positive regulation of corneal type V collagen mRNA: analysis by chicken-human heterokaryon formation.

    Science.gov (United States)

    Linsenmayer, T F; Igoe, F; Gibney, E; Gordon, M K; Birk, D E

    1996-10-10

    Our previous studies have suggested that type V collagen is at least one factor responsible for the characteristically small, uniform diameter of striated collagen fibrils of the corneal stroma. These fibrils, which are heterotypic combinations of collagen types I and V, contain four- to fivefold more type V collagen than those of tendon and sclera. The latter are much larger and more heterodisperse. This high content of type V collagen in cornea is reflected by an equally elevated content of alpha1(V) chain mRNA in corneal fibroblasts. Thus, the increased production of the molecule in cornea appears to be regulated at the level of transcription and/or mRNA stability. One possible explanation for this is that corneal fibroblasts contain positive regulatory factors that specifically upregulate transcription of the type V collagen genes and/or increase their mRNA stability. To test this possibility, we have produced transient heterokaryons by fusing chicken corneal fibroblasts with two human noncorneal cell lines selected as containing little if any alpha1(V) mRNA. If the chicken corneal cells contain positive regulators that can act across species, these regulators should result in increased levels of the human alpha1(V) transcript. The results were evaluated by reverse transcript-polymerase chain reaction employing a primer pair selected for its ability specifically to amplify part of the human alpha1(V) mRNA. In fusions between chicken corneal fibroblasts and the human cell lines, after a lag of 10-14 h the heterokaryon-containing cultures showed de novo appearance or upregulation of human alpha1(V) chain mRNA, compared with that of the parental cell lines. Cultures of the mixed cell types that had not been fused showed no such upregulation, so the effect was not mediated by diffusible substances acting between the cells. Chicken tendon fibroblasts, a low producer of type V collagen, when tested in the same assay, evoked no detectible increase in the human

  14. Diameter preserving linear maps and isometries, II

    Indian Academy of Sciences (India)

    We study linear bijections of simplex spaces A ( S ) which preserve the diameter of the range, that is, the seminorm ϱ ( f ) = sup { | f ( x ) − f ( y ) | : x , y ∈ S } . Author Affiliations. Félix Cabello Sánchez1. Departamento de Matemáticas, Universidad de Extremadura, Avenida de Elvas 06071- Badajoz, Spain. Dates. Manuscript ...

  15. Numerical Analysis of Large Diameter Butterfly Valve

    Science.gov (United States)

    Youngchul, Park; Xueguan, Song

    In this paper, a butterfly valve with the diameter of 1,800 mm was studied. Three-dimensional numerical technique by using commercial code CFX were conducted to observe the flow patterns and to measure flow coefficient, hydrodynamic torque coefficient and so on, when the large butterfly valve operated with various angles and uniform incoming velocity.

  16. Ultrasonic measurement of biparietal diameter and

    African Journals Online (AJOL)

    Summary. Our objective was to verify ultrasonic measurement of biparietal diameter and femur in foetal age determination in the second and third trimester of pregnancy. The prospec- tive cross sectional study was carried out at the ultrasound department of Aberdeen Maternity Hospital Scotland. The study population ...

  17. Kinetics of Angiogenic Responses in Corneal Transplantation.

    Science.gov (United States)

    Inomata, Takenori; Mashaghi, Alireza; Di Zazzo, Antonio; Lee, Sang-Mok; Chiang, Homer; Dana, Reza

    2017-04-01

    To delineate and compare the kinetics of corneal angiogenesis after high-risk (HR) versus low-risk (LR) corneal transplantation. In mice, intrastromal sutures were placed in the recipient graft bed 2 weeks before allogeneic transplantation to induce angiogenesis and amplify the risk of graft rejection. Control (LR) graft recipients did not undergo suture placement, and thus the host bed remained avascular at the time of transplantation. Graft hemangiogenesis and opacity scores were evaluated for 8 weeks by slit-lamp biomicroscopy. Immunohistochemistry was used to measure CD31 (blood vessels) and LYVE-1 (lymphatic vessels) cells. Biphasic kinetics were observed for hemangiogenesis in both HR and LR transplant recipients using clinical and immunohistochemical assessments. The biphasic kinetics were composed of a rise-fall (phase 1) followed by a second rise (phase 2) in the degree of vessels. Compared with LR recipients, HR recipients showed higher hemangiogenesis (whole cornea and graft) throughout 8 weeks. Analyzing grafts revealed sustained presence of lymphatic vessels in HR recipients; however, lymphatic neovessels regressed in LR recipients 2 weeks posttransplantation. In contrast to HR host beds, the LR host bed microenvironment cannot sustain the growth of lymphatic neovessels in allografts, whereas it can sustain continued hemangiogenesis. The sustained presence of lymphatic vessels in HR host beds can facilitate host immunity against allografts and is likely associated with ongoing higher risk of rejection of these grafts in the long term, suggesting that therapeutic interventions targeting inflammation and lymphatic vessels need to be sustained long term in the HR corneal transplant setting.

  18. Mycotic corneal ulcers in upper Assam

    Directory of Open Access Journals (Sweden)

    Reema Nath

    2011-01-01

    Full Text Available Purpose : To study the association of various risk factors and epidemiological variables of mycotic keratitis treated at a tertiary referral hospital of upper Assam. Materials and Methods: In this hospital-based prospective study a total of 310 consecutive corneal ulcer cases attending the ophthalmology outpatient department of Assam Medical College were enrolled between April 2007 and March 2009. After clinical and slit-lamp biomicroscopic examination in all suspected cases, smears and culture examination for fungus was done to establish the etiology. Demographic information and associated probable risk factors of individual cases were noted in a predesigned questionnaire. Results: In 188 (60.6% cases fungal etiology could be established. Out of them 67.6% were males. The most commonly affected age group was 41-50 years (25.5%. The maximum (23.4% cases were reported during the paddy harvesting season in Assam (January and February. Fungal element could be demonstrated in 65.2% cases in direct potassium hydroxide (KOH mount. The commonest predisposing factor was corneal injury (74.5%. While diabetes was a significant systemic predisposing factor in mixed bacterial and fungal infections in 11.1% cases, blocked naso-lacrimal duct was the local predisposing factor in 11.1% of cases. Fusarium solani (25% was the commonest isolate followed by Aspergillus species (19%, Curvularia species (18.5% and Penicillium species (15.2%. Yeasts were isolated in 2.7% (n=5 cases. Conclusions : Ocular trauma was the commonest cause of fungal corneal ulcer in Assam and Fusarium solani was the commonest species responsible for it. Most of the mycotic ulcer cases come from rural areas including the tea gardens.

  19. Corneal surface reconstruction - a short review

    Directory of Open Access Journals (Sweden)

    Madhavan H N

    2009-01-01

    Full Text Available Cornea is the clear, dome-shaped surface that covers the front of the eye and when damage due to burns or injury and several other diseases, stem cells residing in its rim called "limbus" are stimulated to multiply to support growth of new epithelial cells over its surface. If this ready source of stem cells is damaged or destroyed the natural repair is not possible and such a condition is known as corneal limbal stem cell deficiency (CLSCD disease. Stem cell transplant helps such persons to regenerate the corneal surface. Human corneal limbal stem cell transplantation is at present an established procedure with reasonable good clinical outcome particularly when autologous limbal epithelial tissue from a fellow unaffected eye is used. 1, 2 A major concern related to the autograft is the possibility of CLSCD at the donor site, 3 techniques that allowed the expansion of a small limbal biopsy in the laboratory using cell cultures that could be then transplanted to the affected eye have been developed ,4, 5 Human amniotic membrane (HAM is used as a scaffold for both culturing the human limbal epithelial cells and for ocular surface reconstruction with the cultured limbal epithelial cells. 4-7 However, researchers have used alternative scaffolds like collagen 8, fibrin gel 9 and cross-linked gel of fibronectin and fibrin. 10 All these are biological materials and also need for animal 3T3 feeder layer for stem cell cultures. The properties of HAM are unique including antiadhesive effects, bacteriostatic effects, wound protection, pain reduction, and improvement of epithelialization and characteristically lacking imunogenicity. The use of amniotic membrane transplantation (AMT to treat ocular surface abnormalities was first reported by Graziella Pellegrini, chief of stem cell laboratory at Giovanni Paolo Hospital in Venice, Italy, who was the first to demonstrate the limbal stem cell transplant in 1997. Amniotic membrane has been successfully used in

  20. Corneal collagen cross-linking effects on pseudophakic bullous keratopathy

    Directory of Open Access Journals (Sweden)

    Mohammad Mirzaei

    2014-05-01

    Full Text Available AIM: To evaluate the efficacy of riboflavin administration and ultraviolet A(UVAcross-linking on advanced symptomatic bullous keratopathy. METHODS: Fifteen patients with symptomatic pseudophakic bullous keratopathy(PBKwere included. Slit-lamp examination, visual acuity, foreign body sensation(FBSquestionnaire, corneal clarity grading, ocular pain intensity scale and corneal thickness measures with Pentacam and ultrasound pachymetry(UP, were performed before corneal cross-linking and 1 and 6mo thereafter. After using sodium chloride solution, for one week, the central 8mm(diameterof the corneal epithelium was removed, and cross-linking, with riboflavin instillation every 3min for 30min, and UVA irradiation for 30min was performed. RESULTS: Five males and 10 females with mean age of 66±13y were included. Mean follow up time was 6.2mo. Corneal transparency in all eyes was statistically significantly better 1 month after treatment than preoperatively(PP= 0.218. Foreign body sensation subsided in 70% of patients. The average CCT decreased within 1mo after the procedure(PP=0.006. The improvement in mean CDVA from preoperatively to 1mo postoperatively was statistically significant(P=0.010. At 6mo, no significant differences were observed(P=0.130. The pain scores at 1mo were statistically significantly better than preoperatively(P=0.007. At 6mo, however the mean pain score was higher than at 1mo and not statistically significantly different from the preoperative score(P=0.070. CONCLUSION: Corneal CXL significantly improved corneal transparency, corneal thickness, and ocular pain 1 month postoperatively. However, it did not seem to have a long-lasting effect in decreasing pain and maintaining corneal transparency in patients with PBK. This procedure extends the time interval for corneal transplantation and increases visualization at DSAEK procedure.

  1. Corneal Higher-order Aberrations and Visual Improvement Following Corneal Transplantation in Treating Herpes Simplex Keratitis.

    Science.gov (United States)

    Shimizu, Eisuke; Yamaguchi, Takefumi; Tomida, Daisuke; Yagi-Yaguchi, Yukari; Satake, Yoshiyuki; Tsubota, Kazuo; Shimazaki, Jun

    2017-12-01

    To examine corneal higher-order aberrations (HOAs) and visual improvement following corneal transplantation in treating corneal scar caused by herpes simplex keratitis (HSK). Retrospective consecutive case series. This study included a total of 52 eyes: 18 eyes of normal subjects, and 34 eyes of consecutive patients with corneal scar owing to HSK who underwent penetrating keratoplasty (PKP, 17 eyes) or deep anterior lamellar keratoplasty (DALK, 17 eyes). HOAs of the anterior, posterior surfaces and the total cornea were analyzed by anterior segment optical coherence tomography. The correlations between corneal HOAs and visual improvement were also analyzed. Mean logarithm of the minimal angle of resolution (logMAR) visual acuity significantly improved from 1.40 ± 0.70 to 0.46 ± 0.45 after corneal transplantation (P transplantation (PKP: from 1.16 ± 0.59 μm to 0.58 ± 0.35 μm, P = .035, DALK: from 0.94 ± 0.57 μm to 0.37 ± 0.18 μm, P = .004). Visual acuity following corneal transplantation was correlated with the corneal HOAs at 12 months (r = 0.53, P = .01). Visual improvement at 3, 6, and 12 months was positively correlated with preoperative HOAs of the total cornea and posterior surface (all P transplantation in eyes with HSK. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. In Vivo Confocal Microscopic Observation of Lamellar Corneal Transplantation in the Rabbit Using Xenogenic Acellular Corneal Scaffolds as a Substitute

    Science.gov (United States)

    Feng, Yun; Wang, Wei

    2015-01-01

    Background: The limiting factor to corneal transplantation is the availability of donors. Research has suggested that xenogenic acellular corneal scaffolds (XACS) may be a possible alternative to transplantation. This study aimed to investigate the viability of performing lamellar corneal transplantation (LCT) in rabbits using canine XACS. Methods: Fresh dog corneas were decellularized by serial digestion, and LCT was performed on rabbit eyes using xenogeneic decellularized corneal matrix. Cellular and morphological changes were observed by slit-lamp, light, and scanning electron microscopy at 7, 30 and 90 days postoperatively. Immunocytochemical staining for specific markers such as keratin 3, vimentin and MUC5AC, was used to identify cells in the graft. Results: Decellularized xenogenic corneal matrix remained transparent for about 1-month after LCT. The recipient cells were able to survive and proliferate into the grafts. Three months after transplantation, grafts had merged with host tissue, and graft epithelialization and vascularization had occurred. Corneal nerve fibers were able to grow into the graft in rabbits transplanted with XACS. Conclusions: Xenogenic acellular corneal scaffolds can maintain the transparency of corneal grafts about 1-month and permit growth of cells and nerve fibers, and is, therefore, a potential substitute or carrier for a replacement cornea. PMID:25836615

  3. Utilización del bevacizumab en la neovascularización corneal Use of Bevacizumab in corneal neovascularization

    Directory of Open Access Journals (Sweden)

    Taimi Cárdenas Díaz

    2012-12-01

    Full Text Available La neovascularización corneal es causa de pérdida de su transparencia y también es un factor de riesgo para el rechazo secundario de trasplantes en esa estructura. El bevacizumab es un anticuerpo monoclonal humanizado que bloquea selectivamente la cascada de formación del VEGF y con esto disminuye la formación de vasos sanguíneos. Se presentan tres casos con neovascularización corneal por diferentes causas, a los cuales se le administró tres dosis subconjuntival de 2,5 mg de bevacizumab, con una frecuencia mensual. En los ojos tratados se observó una regresión parcial de la neovascularización corneal y fue más visible en el paciente con antecedente de quemadura corneal.Neovascularization of the cornea is a cause of loss of transparency of the same and is also a risk factor for secondary rejection corneal transplants. Bevacizumab is a humanized monoclonal antibody that selectively blocks the formation of the VEGF cascade and, with this, decreases the formation of blood vessels. Three cases with corneal neovascularization from different causes were presented, which were given three doses of 2.5 mg subconjunctival bevacizumab once a month. A partial regression of corneal neovascularization was observed in the treated eyes, being more visible in the patient with a history of corneal burn.

  4. Role of corneal epithelium in riboflavin/ultraviolet-A mediated corneal cross-linking treatment in rabbit eyes.

    Science.gov (United States)

    Tao, Xiangchen; Yu, Haiqun; Zhang, Yong; Li, Zhiwei; Jhanji, Vishal; Ni, Shouxiang; Wang, Ya; Mu, Guoying

    2013-01-01

    To evaluate the role of corneal epithelium in riboflavin/ultraviolet-A (UVA) mediated corneal collagen cross-linking treatment. Fifty New Zealand rabbits were divided into 5 groups: UVA treatment with or without corneal epithelium, UVA+riboflavin treatment with or without corneal epithelium, and control without any treatment. All rabbits were sacrificed after irradiation and subsequently 4 mm × 10 mm corneal strips were harvested for biomechanical evaluation. UVA irradiation alone did not enhance the maximal stress and Young's modulus of corneal specimens with (3.15 ± 0.56 mpa, 1.00 ± 0.09 mpa) or without (3.53 ± 0.85 mpa, 0.94 ± 0.21 mpa) the corneal epithelium, compared to specimens in the control group (4.30 ± 0.68 mpa, 1.03 ± 0.24 mpa). However, UVA irradiation combined with riboflavin significantly increased the maximal stress and Young's modulus of corneal specimens with (5.27 ± 1.09 mpa, 1.23 ± 0.23 mpa, P cornea in UVA+riboflavin and "epithelium-off" group were 35.9% and 15.4% higher compared to the UVA+riboflavin and "epithelium-on" group, respectively (P biomechanical properties of the cornea with and without epithelial removal. However, corneas without epithelium seem to benefit more compared to corneas with the epithelium.

  5. Combined corneal allotransplantation and vitreoretinal surgery using an Eckardt temporary keratoprosthesis: analysis for factors determining corneal allograft survival

    Directory of Open Access Journals (Sweden)

    Lee DS

    2014-02-01

    Full Text Available Dae Seung Lee,1 Jang Won Heo,1 Hyuk Jin Choi,2 Mee Kum Kim,1 Won Ryang Wee,1 Joo Youn Oh1 1Department of Ophthalmology, Seoul National University Hospital, 2Seoul National University Hospital Healthcare System Gangnam Center, Seoul, Korea Purpose: To evaluate the outcome of corneal allotransplantation in combined penetrating keratoplasty and vitreoretinal surgery using a temporary keratoprosthesis, and to determine the factors affecting corneal allograft survival. Methods: We reviewed the medical charts of eleven patients who had undergone combined corneal allotransplantation and pars plana vitrectomy using an Eckardt temporary keratoprosthesis, for the treatment of corneal opacification and vitreoretinal disease. The survival rates of the corneal grafts were assessed, and patient demographics, the diagnosis of corneal and retinal disease, the preoperative ocular characteristics, and surgical methods were compared between the group with graft survival and that with graft failure. Results: The causes of corneal opacification were corneal laceration (four eyes, infectious keratitis (four eyes, atopic keratitis (one eye, rejected corneal graft (one eye, and uveitis-related bullous keratopathy (one eye. The preoperative diagnoses included endophthalmitis (six eyes, posterior uveitis (one eye, vitreous opacity or hemorrhage (two eyes, and rhegmatogenous retinal detachment (two eyes. The survival rate of the corneal allografts was 27.3% (3/11 eyes. The mean survival time was 391 days during the mean follow-up period of 687 days. The retinal surgery was successful in 81.8% (9/11 eyes of cases. The presence of active inflammation in the cornea at the time of surgery was significantly correlated with graft rejection (P=0.004. Other factors, including age, the presence of glaucoma, type of corneal and retinal disease, or type of retinal surgery, such as silicone oil injection and gas tamponade, had no significant correlation with graft rejection

  6. Riboflavin/UVA collagen cross-linking-induced changes in normal and keratoconus corneal stroma.

    Directory of Open Access Journals (Sweden)

    Sally Hayes

    Full Text Available PURPOSE: To determine the effect of Ultraviolet-A collagen cross-linking with hypo-osmolar and iso-osmolar riboflavin solutions on stromal collagen ultrastructure in normal and keratoconus ex vivo human corneas. METHODS: Using small-angle X-ray scattering, measurements of collagen D-periodicity, fibril diameter and interfibrillar spacing were made at 1 mm intervals across six normal post-mortem corneas (two above physiological hydration (swollen and four below (unswollen and two post-transplant keratoconus corneal buttons (one swollen; one unswollen, before and after hypo-osmolar cross-linking. The same parameters were measured in three other unswollen normal corneas before and after iso-osmolar cross-linking and in three pairs of swollen normal corneas, in which only the left was cross-linked (with iso-osmolar riboflavin. RESULTS: Hypo-osmolar cross-linking resulted in an increase in corneal hydration in all corneas. In the keratoconus corneas and unswollen normal corneas, this was accompanied by an increase in collagen interfibrillar spacing (p<0.001; an increase in fibril diameter was also seen in two out of four unswollen normal corneas and one unswollen keratoconus cornea (p<0.001. Iso-osmolar cross-linking resulted in a decrease in tissue hydration in the swollen normal corneas only. Although there was no consistent treatment-induced change in hydration in the unswollen normal samples, iso-osmolar cross-linking of these corneas did result in a compaction of collagen fibrils and a reduced fibril diameter (p<0.001; these changes were not seen in the swollen normal corneas. Collagen D-periodicity was not affected by either treatment. CONCLUSION: The observed structural changes following Ultraviolet-A cross-linking with hypo-osmolar or iso-osmolar riboflavin solutions are more likely a consequence of treatment-induced changes in tissue hydration rather than cross-linking.

  7. 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.

  8. Acute corneal hydrops during pregnancy with spontaneous resolution after corneal cross-linking for keratoconus: a case report.

    Science.gov (United States)

    Stock, Ricardo Alexandre; Thumé, Thaís; Bonamigo, Elcio Luiz

    2017-02-25

    Keratoconus may progress to acute corneal hydrops even after cross-linking. In some cases, keratoconus progresses during pregnancy. In this report, we present a case of a patient with increased anterior stromal resistance after cross-linking that would favor nonprogression of keratoconus during pregnancy. We report that cross-linking is likely to have had a protective effect in a white pregnant patient with acute corneal hydrops who showed rapid improvement, as documented by corneal topography. Improvement occurred within 8 days, whereas up to 250 days are reported in the literature. No keratoconus progression occurred in the 20-month follow-up period. Cross-linking failed to prevent the occurrence of acute corneal hydrops after rupture of Descemet's membrane but most likely helped to accelerate the resolution of the condition. Corneal hardening resulting from cross-linking may have also contributed to stabilizing keratoconus during pregnancy.

  9. Keratometry versus total corneal refractive power: Analysis of measurement repeatability with 5 different devices in normal eyes with low astigmatism.

    Science.gov (United States)

    Fityo, Sylvia; Bühren, Jens; Shajari, Mehdi; Kohnen, Thomas

    2016-04-01

    To analyze the repeatability of corneal astigmatism measurements with 2 autokeratometers (IOLMaster 500 and Lenstar LS 900), 2 Placido topographers (Keratron Scout and Atlas 9000), and a Scheimpflug tomographer (Pentacam HR). Department of Ophthalmology, Goethe University, Frankfurt, Germany. Prospective case series. The inclusion criteria were a minimum age of 18 years, corneal astigmatism of 3.00 diopters or less, and patient's consent to participate in the study. The main exclusion criteria were corneal pathologies, trauma, previous surgery, hard contact lens wear in the previous 3 months, and soft contact lens wear in the previous 6 weeks. In addition to manifest refraction and visual acuity measurements, all subjects had 2 full measurements of 1 eye using each device. Anterior corneal astigmatism and total corneal refractive power via calculations derived from the Scheimpflug tomographer were evaluated. Statistical analysis was performed using the Bland-Altman method and multiple linear regression analysis. Forty-five eyes of 45 subjects (mean age 53.11 years ± 10.43 [SD]; 23 left eyes; 33 women) were included. The mean intermeasurement differences were approximately zero for all devices. The relative coefficient of repeatability of anterior corneal astigmatism, steep axis, and the vector analysis parameter J180 were lowest with the Scheimpflug tomographer. Total corneal refractive power measured with the Scheimpflug tomographer showed the highest repeatability in the larger diameter zones. The Scheimpflug tomographer yielded higher repeatability of corneal astigmatism measurements, with total corneal refractive power measurements being as repeatable as established metrics. Dr. Kohnen receives research support from Abbott Medical Optics Inc., Alcon Pharma GmbH, Bausch & Lomb GmbH, Carl Zeiss Meditec Vertriebsgesellschaft mbH, Hoya Surgical Optics GmbH, Oculus Optikgeräte GmbH, and Schwind eye-tech-solutions GmbH and Co. KG. He receives travel

  10. Corneal elasticity after oxygen enriched high intensity corneal cross linking assessed using atomic force microscopy.

    Science.gov (United States)

    Diakonis, Vasilios F; Likht, Nikita Y; Yesilirmak, Nilufer; Delgado, Desiree; Karatapanis, Andreas E; Yesilirmak, Yener; Fraker, Christopher; Yoo, Sonia H; Ziebarth, Noël M

    2016-12-01

    The purpose of this study was to assess anterior and mid corneal stromal elasticity after high intensity (HI) corneal cross linking (CXL), with and without oxygen (O2) enrichment, and compare these results to conventional CXL. Experiments were performed on 25 pairs of human cadaver eyes, divided into four different groups. Group 1 included corneas that did not receive treatment and served as controls; Group 2 included corneas that received conventional CXL treatment (Dresden Protocol: corneal epithelial debridement, 30 min of riboflavin pretreatment followed by 30 min of exposure to 3 mW/cm(2) of ultraviolet light); Group 3 included corneas that received HI CXL treatment (corneal epithelial debridement, 30 min of riboflavin pretreatment followed by 3 min of exposure to 30mW/cm(2) of ultraviolet light); and Group 4 included corneas that received the same treatment as Group 3, except that they were enriched with oxygen (4 L per minute pure O2 gas stream) during ultraviolet irradiation. In each group, corneas were subdivided to assess anterior stromal elasticity and mid stromal elasticity. Corneal stromal elasticity was quantified using Atomic Force Microscopy (AFM) through micro-indentation. Young's modulus for the anterior corneal stroma was 14.5 ± 6.0 kPa, 80.7 ± 44.6 kPa, 36.6 ± 10.5 kPa, and 30.6 ± 9.2 kPa, for groups 1, 2, 3 and 4 respectively. Young's modulus for the mid corneal stroma was 5.8 ± 2.0 kPa, 20.7 ± 4.3 kPa, 12.1 ± 4.9 kPa, and 11.7 ± 3.7 kPa, for groups 1, 2, 3 and 4, respectively. In the anterior stromal region, conventional CXL demonstrated a significantly different result from the control, whereas the two HI CXL protocols were not significantly different from the control. There were no statistical differences between the two HI CXL protocols, although only the HI CXL protocol with O2 enrichment was significantly different from the conventional CXL group. In the mid stromal region, once again only

  11. The heritability of glaucoma-related traits corneal hysteresis, central corneal thickness, intraocular pressure, and choroidal blood flow pulsatility.

    Science.gov (United States)

    Freeman, Ellen E; Roy-Gagnon, Marie-Hélène; Descovich, Denise; Massé, Hugues; Lesk, Mark R

    2013-01-01

    The purpose of this work was to investigate the heritability of potential glaucoma endophenotypes. We estimated for the first time the heritability of the pulsatility of choroidal blood flow. We also sought to confirm the heritability of corneal hysteresis, central corneal thickness, and 3 ways of measuring intraocular pressure. Measurements were performed on 96 first-degree relatives recruited from Maisonneuve-Rosemont Hospital in Montreal. Corneal hysteresis was determined using the Reichert Ocular Response Analyser. Central corneal thickness was measured with an ultrasound pachymeter. Three measures of intraocular pressure were obtained: Goldmann-correlated and corneal compensated intraocular pressure using the Ocular Response Analyser, and Pascal intraocular pressure using the Pascal Dynamic Contour Tonometer. The pulsatility of choroidal blood velocity and flow were measured in the sub-foveolar choroid using single-point laser Doppler flowmetry (Oculix). We estimated heritability using maximum-likelihood variance components methods implemented in the SOLAR software. No significant heritability was detected for the pulsatility of choroidal blood flow or velocity. The Goldman-correlated, corneal compensated, and Pascal measures of intraocular pressure measures were all significantly heritable at 0.94, 0.79, and 0.53 after age and sex adjustment (p = 0.0003, p = 0.0023, p = 0.0239). Central corneal thickness was significantly heritable at 0.68 (p = 0.0078). Corneal hysteresis was highly heritable but the estimate was at the upper boundary of 1.00 preventing us from giving a precise estimate. Corneal hysteresis, central corneal thickness, and intraocular pressure are all heritable and may be suitable as glaucoma endophenotypes. The pulsatility of choroidal blood flow and blood velocity were not significantly heritable in this sample.

  12. The heritability of glaucoma-related traits corneal hysteresis, central corneal thickness, intraocular pressure, and choroidal blood flow pulsatility.

    Directory of Open Access Journals (Sweden)

    Ellen E Freeman

    Full Text Available PURPOSE: The purpose of this work was to investigate the heritability of potential glaucoma endophenotypes. We estimated for the first time the heritability of the pulsatility of choroidal blood flow. We also sought to confirm the heritability of corneal hysteresis, central corneal thickness, and 3 ways of measuring intraocular pressure. METHODS: Measurements were performed on 96 first-degree relatives recruited from Maisonneuve-Rosemont Hospital in Montreal. Corneal hysteresis was determined using the Reichert Ocular Response Analyser. Central corneal thickness was measured with an ultrasound pachymeter. Three measures of intraocular pressure were obtained: Goldmann-correlated and corneal compensated intraocular pressure using the Ocular Response Analyser, and Pascal intraocular pressure using the Pascal Dynamic Contour Tonometer. The pulsatility of choroidal blood velocity and flow were measured in the sub-foveolar choroid using single-point laser Doppler flowmetry (Oculix. We estimated heritability using maximum-likelihood variance components methods implemented in the SOLAR software. RESULTS: No significant heritability was detected for the pulsatility of choroidal blood flow or velocity. The Goldman-correlated, corneal compensated, and Pascal measures of intraocular pressure measures were all significantly heritable at 0.94, 0.79, and 0.53 after age and sex adjustment (p = 0.0003, p = 0.0023, p = 0.0239. Central corneal thickness was significantly heritable at 0.68 (p = 0.0078. Corneal hysteresis was highly heritable but the estimate was at the upper boundary of 1.00 preventing us from giving a precise estimate. CONCLUSION: Corneal hysteresis, central corneal thickness, and intraocular pressure are all heritable and may be suitable as glaucoma endophenotypes. The pulsatility of choroidal blood flow and blood velocity were not significantly heritable in this sample.

  13. Effects of altered corneal stiffness on native and postoperative LASIK corneal biomechanical behavior: A whole-eye finite element analysis.

    Science.gov (United States)

    Roy, Abhijit Sinha; Dupps, William J

    2009-10-01

    To investigate the impact of corneal elasticity on corneal shape changes before and after simulated LASIK with and without consideration of whole-eye biomechanics. A finite element whole-eye model of a human eye was constructed. The cornea was modeled as hyperelastic and incompressible using experimental data representing a range of corneal stiffness. The corneal response to intraocular pressure loading and LASIK for 2.00, 4.00, and 6.00 diopters of spherical myopia was analyzed as a function of corneal stiffness and limbal boundary conditions. Myopic LASIK produced different degrees of central flattening and postoperative ametropia in low-stiffness and high-stiffness corneas. Although a cornea-only model demonstrated maximum stresses and displacements in the central cornea and predicted residual myopia, a whole-eye model with equivalent corneal stiffness predicted greater paracentral displacements and less myopic undercorrection. In a whole-eye model with a stiffer cornea, maximum displacements shifted further toward the limbus, favoring additional mechanically mediated central flattening and refractive overcorrection (hyperopia). In postoperative LASIK models thinned by high myopic corrections, corneal stiffening caused central cornea flattening. Differences in the corneoscleral stiffness relationship affect simulated refractive outcomes after LASIK and may be a source of individual variation in refractive surgery outcomes. A whole-eye model allowing limbal motion illustrates a stiffness-dependent biomechanical balance between central corneal flattening and pre-ectatic weakening of the corneal apex not demonstrated in previous computational models and provides insight into under- and overcorrection in myopic LASIK and the previously unexplained phenomenon of corneal flattening after therapeutic collagen cross-linking for keratoconus. Copyright 2009, SLACK Incorporated.

  14. On finding minimum-diameter clique trees

    Energy Technology Data Exchange (ETDEWEB)

    Blair, J.R.S. (Tennessee Univ., Knoxville, TN (United States). Dept. of Computer Science); Peyton, B.W. (Oak Ridge National Lab., TN (United States))

    1991-08-01

    It is well-known that any chordal graph can be represented as a clique tree (acyclic hypergraph, join tree). Since some chordal graphs have many distinct clique tree representations, it is interesting to consider which one is most desirable under various circumstances. A clique tree of minimum diameter (or height) is sometimes a natural candidate when choosing clique trees to be processed in a parallel computing environment. This paper introduces a linear time algorithm for computing a minimum-diameter clique tree. The new algorithm is an analogue of the natural greedy algorithm for rooting an ordinary tree in order to minimize its height. It has potential application in the development of parallel algorithms for both knowledge-based systems and the solution of sparse linear systems of equations. 31 refs., 7 figs.

  15. 29 mm Diameter Test Target Design Report

    Energy Technology Data Exchange (ETDEWEB)

    Woloshun, Keith Albert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dale, Gregory E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Olivas, Eric Richard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Naranjo, Angela Carol [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Romero, Frank Patrick [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-08-15

    The Northstar target for Mo99 production is made up of Mo100 disks in a stack separated by coolant gaps for helium flow. A number of targets have been tested at ANL for both production of Mo99 and for thermal-hydraulic performance. These have all been with a 12 mm diameter target, even while the production goals have increased the diameter to now 29 mm. A 29 mm diameter target has been designed that is consistent with the ANL beam capabilities and the capabilities of the helium circulation system currently in use at ANL. This target is designed for 500 μA at 35 MeV electrons. While the plant design calls for 42 MeV, the chosen design point is more favorable and higher power given the limits of the ANL accelerator. The intended beam spot size is 12 mm FWHM, but the thermal analysis presented herein conservatively assumed a 10 mm FWHM beam, which results in a 44% higher beam current density at beam center.

  16. IOL Power Calculation after Corneal Refractive Surgery

    Directory of Open Access Journals (Sweden)

    Maddalena De Bernardo

    2014-01-01

    Full Text Available Purpose. To describe the different formulas that try to overcome the problem of calculating the intraocular lens (IOL power in patients that underwent corneal refractive surgery (CRS. Methods. A Pubmed literature search review of all published articles, on keyword associated with IOL power calculation and corneal refractive surgery, as well as the reference lists of retrieved articles, was performed. Results. A total of 33 peer reviewed articles dealing with methods that try to overcome the problem of calculating the IOL power in patients that underwent CRS were found. According to the information needed to try to overcome this problem, the methods were divided in two main categories: 18 methods were based on the knowledge of the patient clinical history and 15 methods that do not require such knowledge. The first group was further divided into five subgroups based on the parameters needed to make such calculation. Conclusion. In the light of our findings, to avoid postoperative nasty surprises, we suggest using only those methods that have shown good results in a large number of patients, possibly by averaging the results obtained with these methods.

  17. IOL power calculation after corneal refractive surgery.

    Science.gov (United States)

    De Bernardo, Maddalena; Capasso, Luigi; Caliendo, Luisa; Paolercio, Francesco; Rosa, Nicola

    2014-01-01

    To describe the different formulas that try to overcome the problem of calculating the intraocular lens (IOL) power in patients that underwent corneal refractive surgery (CRS). A Pubmed literature search review of all published articles, on keyword associated with IOL power calculation and corneal refractive surgery, as well as the reference lists of retrieved articles, was performed. A total of 33 peer reviewed articles dealing with methods that try to overcome the problem of calculating the IOL power in patients that underwent CRS were found. According to the information needed to try to overcome this problem, the methods were divided in two main categories: 18 methods were based on the knowledge of the patient clinical history and 15 methods that do not require such knowledge. The first group was further divided into five subgroups based on the parameters needed to make such calculation. In the light of our findings, to avoid postoperative nasty surprises, we suggest using only those methods that have shown good results in a large number of patients, possibly by averaging the results obtained with these methods.

  18. Bilateral Keratectasia 34 Years after Corneal Transplant

    Directory of Open Access Journals (Sweden)

    Xavier Valldeperas

    2010-07-01

    Full Text Available We report the clinical findings of a patient with severe bilateral keratectasia 34 years after a penetrating keratoplasty (PK in both eyes. An otherwise healthy 67-year-old man complained of deterioration of the eyesight in both eyes over the last 6 months. The patient was diagnosed with bilateral keratoconus at the age of 32 years, and he underwent a bilateral PK. At presentation, visual acuity was 20/200 in the right eye and light perception in the left eye. A Pentacam pachymetric map revealed a central pachymetry of 720 µm in the right eye and of 710 µm in the left eye, as well as an average paracentral pachymetry of 436 and 270 µm in the 9-mm zone in the right and the left eye, respectively. Corneal topography revealed bilateral irregular and asymmetric bowing with generalized steepening and high corneal power. We describe a case of bilateral keratectasia 34 years after PK in a patient who was originally diagnosed with bilateral keratoconus.

  19. Biomechanical modeling of refractive corneal surgery.

    Science.gov (United States)

    Alastrué, V; Calvo, B; Peña, E; Doblaré, M

    2006-02-01

    The aim of refractive corneal surgery is to modify the curvature of the cornea to improve its dioptric properties. With that goal, the surgeon has to define the appropriate values of the surgical parameters in order to get the best clinical results, i.e., laser and geometric parameters such as depth and location of the incision, for each specific patient. A biomechanical study before surgery is therefore very convenient to assess quantitatively the effect of each parameter on the optical outcome. A mechanical model of the human cornea is here proposed and implemented under a finite element context to simulate the effects of some usual surgical procedures, such as photorefractive keratectomy (PRK), and limbal relaxing incisions (LRI). This model considers a nonlinear anisotropic hyperelastic behavior of the cornea that strongly depends on the physiological collagen fibril distribution. We evaluate the effect of the incision variables on the change of curvature of the cornea to correct myopia and astigmatism. The obtained results provided reasonable and useful information in the procedures analyzed. We can conclude from those results that this model reasonably approximates the corneal response to increasing pressure. We also show that tonometry measures of the IOP underpredicts its actual value after PRK or LASIK surgery.

  20. Computational modeling of corneal refractive surgery

    Science.gov (United States)

    Cabrera Fernandez, Delia; Niazy, Abdel-Salam M.; Kurtz, Ronald M.; Djotyan, Gagik P.; Juhasz, Tibor

    2004-07-01

    A finite element method was used to study the biomechanical behavior of the cornea and its response to refractive surgery when stiffness inhomogeneities varying with depth are considered. Side-by-side comparisons of different constitutive laws that have been commonly used to model refractive surgery were also performed. To facilitate the comparison, the material property constants were identified from the same experimental data, which were obtained from mechanical tests on corneal strips and membrane inflation experiments. We then validated the resulting model by comparing computed refractive power changes with clinical results. The model developed provides a much more predictable refractive outcome when the stiffness inhomogeneities of the cornea and nonlinearities of the deformations are included in the finite element simulations. Thus, it can be stated that the inhomogeneous model is a more accurate representation of the corneal material properties in order to model the biomechanical effects of refractive surgery. The simulations also revealed that the para-central and peripheral parts of the cornea deformed less in response to pressure loading compared to the central cornea and the limbus. Furthermore, the deformations in response to pressure loading predicted by the non-homogeneous and nonlinear model, showed that the para-central region is mechanically enhanced in the meridional direction. This result is in agreement with the experimentally documented regional differences reported in the literature by other investigators.

  1. Corneal polarimetry after LASIK refractive surgery

    Science.gov (United States)

    Bueno, Juan M.; Berrio, Esther; Artal, Pablo

    2006-01-01

    Imaging polarimetry provides spatially resolved information on the polarization properties of a system. In the case of the living human eye, polarization could be related to the corneal biomechanical properties, which vary from the normal state as a result of surgery or pathologies. We have used an aberro-polariscope, which we recently developed, to determine and to compare the spatially resolved maps of polarization parameters across the pupil between normal healthy and post-LASIK eyes. The depolarization distribution is not uniform across the pupil, with post-surgery eyes presenting larger levels of depolarization. While retardation increases along the radius in normal eyes, this pattern becomes irregular after LASIK refractive surgery. The maps of slow axis also differ in normal and post-surgery eyes, with a larger disorder in post-LASIK eyes. Since these changes in polarization indicate subtle structural modifications of the cornea, this approach can be useful in a clinical environment to follow the biomechanical and optical changes of the cornea after refractive surgery or for the early diagnosis of different corneal pathologies.

  2. Femtosecond laser's application in the corneal surgery

    Directory of Open Access Journals (Sweden)

    Shu-Liang Wang

    2015-10-01

    Full Text Available With the rapid development over the past two decades,femtosecond(10-15slasers(FShas become a new application in ophthalmic surgery. As laser power is defined as energy delivered per unit time, decreasing the pulse duration to femtosecond level(100fsnot only increases the power delivered but also decreases the fluence threshold for laser induced optical breakdown. In ablating tissue, FS has an edge over nanosecond lasers as there is minimal collateral damage from shock waves and heat conduction during surgical ablation. Thus, application of FS has been widely spread, from flap creation for laser-assisted in situ keratomileusis(LASIKsurgery, cutting of donor and recipient corneas in keratoplasty, creation of pockets for intracorneal ring implantation. FS applied in keratoplasty is mainly used in making graft and recipient bed, and can exactly cut different tissue of keratopathy. FS can also cut partial tissue of cornea, even if it is under the moderate corneal macula and corneal edema condition.

  3. Corneal biomechanical properties in healthy children measured by corneal visualization scheimpflug technology.

    Science.gov (United States)

    He, Miao; Ding, Hui; He, Hong; Zhang, Chi; Liu, Liangping; Zhong, Xingwu

    2017-05-17

    The aim of this study was to evaluate corneal biomechanical properties in a population of healthy children in China using corneal visualization Scheimpflug technology (CST). All children underwent complete bi-ocular examinations. CST provided intraocular pressure (IOP) and corneal biomechanical parameters, including time, velocity, length and deformation amplitude at first applanation (A1T, A1V, A1L, A1DA), at second applanation (A2T, A2V, A2L, A2DA), highest concavity time (HCT), maximum deformation amplitude (MDA), peak distance (PD), and radius of curvature (RoC). Pearson correlation analysis was used to assess the impacts of demographic factors, central corneal thickness (CCT), spherical equivalent (SE), and IOP on corneal biomechanics. One hundred eight subjects (32 girls and 76 boys) with the mean age of 10.80 ± 4.13 years (range 4 to18 years) were included in the final analyses. The right and left eyes were highly symmetrical in SE (p = 0.082), IOP (p = 0.235), or CCT (p = 0.210). Mean A1T of the right eyes was 7.424 ± 0.340 ms; the left eyes 7.451 ± 0.365 ms. MDA was 0.993 ± 0.102 mm in the right eyes and 0.982 ± 0.100 mm in the left eyes. Mean HCT of the right eyes was 16.675 ± 0.502 ms; the left eyes 16.735 ± 0.555 ms. All CST parameters of both eye were remarkably symmetrical with the exception of A2L (p = 0.006), A1DA (p = 0.025). The majority of CST parameters of both eyes were significantly correlated with CCT and IOP (p corneal biomechanics in healthy children eyes. Several CST biomechanical parameters in children are modified by CCT and IOP.

  4. Corneal power evaluation after myopic corneal refractive surgery using artificial neural networks.

    Science.gov (United States)

    Koprowski, Robert; Lanza, Michele; Irregolare, Carlo

    2016-11-15

    Efficacy and high availability of surgery techniques for refractive defect correction increase the number of patients who undergo to this type of surgery. Regardless of that, with increasing age, more and more patients must undergo cataract surgery. Accurate evaluation of corneal power is an extremely important element affecting the precision of intraocular lens (IOL) power calculation and errors in this procedure could affect quality of life of patients and satisfaction with the service provided. The available device able to measure corneal power have been tested to be not reliable after myopic refractive surgery. Artificial neural networks with error backpropagation and one hidden layer were proposed for corneal power prediction. The article analysed the features acquired from the Pentacam HR tomograph, which was necessary to measure the corneal power. Additionally, several billion iterations of artificial neural networks were conducted for several hundred simulations of different network configurations and different features derived from the Pentacam HR. The analysis was performed on a PC with Intel® Xeon® X5680 3.33 GHz CPU in Matlab® Version 7.11.0.584 (R2010b) with Signal Processing Toolbox Version 7.1 (R2010b), Neural Network Toolbox 7.0 (R2010b) and Statistics Toolbox (R2010b). A total corneal power prediction error was obtained for 172 patients (113 patients forming the training set and 59 patients in the test set) with an average age of 32 ± 9.4 years, including 67% of men. The error was at an average level of 0.16 ± 0.14 diopters and its maximum value did not exceed 0.75 dioptres. The Pentacam parameters (measurement results) providing the above result are tangential anterial/posterior. The corneal net power and equivalent k-reading power. The analysis time for a single patient (a single eye) did not exceed 0.1 s, whereas the time of network training was about 3 s for 1000 iterations (the number of neurons in the hidden layer was 400).

  5. Punctiform and Polychromatophilic Dominant Pre-Descemet Corneal Dystrophy.

    Science.gov (United States)

    Lagrou, Lisa; Midgley, Julian; Romanchuk, Kenneth Gerald

    2016-04-01

    To describe the slit-lamp appearance and corneal confocal microscopy of autosomal dominant punctiform and polychromatophilic pre-Descemet corneal dystrophy in 3 members of the same family. Slit-lamp examination of a 9-year-old boy showed bilateral polychromatophilic corneal opacities in a pre-Descemet membrane location evenly deposited limbus to limbus, both horizontally and vertically, with an intervening clear cornea. The corneal endothelium was normal on corneal confocal microscopy, with hyperreflective opacities of various sizes located pre-Descemet membrane. Slit-lamp examination of the patient's father and brother revealed identical crystalline deposition in the pre-Descemet corneal stroma. The remainders of the eye examinations were otherwise normal in all 3 individuals, and all were asymptomatic. The general physical examination and laboratory investigations of the patient were all normal, as were the laboratory investigations of the other 2 family members. There was no progression in the corneal findings over 6 months of follow-up. These patients likely illustrate a rare autosomal dominant pre-Descemet crystalline keratopathy that has been reported only once previously.

  6. Corneal biomechanical properties in patients with recurrent anterior uveitis.

    Science.gov (United States)

    Turan-Vural, Ece; Torun Acar, Banu; Sevim, Mehmet Sahin; Buttanri, Ibrahim Bulent; Acar, Suphi

    2012-10-01

    This study aimed to investigate the biomechanical changes in cornea in patients with recurrent anterior uveitis in comparison to healthy controls. Eighty-five eyes in 51 patients with inactive recurrent anterior uveitis (25 male, 26 female) and 34 eyes of 34 age-matched control subjects (16 male, 18 female) were included. The following measurements were done and compared between patients and controls: corneal hysteresis, corneal response factor, intraocular pressure, and central corneal thickness. Patients had significantly lower mean corneal hysteresis (8.57 ± 1.60 versus 10.91 ± 1.41, p = .001) and corneal resistance factor (9.24 ± 1.68 versus 11.56 ± 1.46, p = .001) when compared to controls. Among patients, corneal hysteresis and corneal resistance factor did not correlate with duration of the disease or number of attacks per year. Anterior uveitis seems to be associated with impaired biomechanical strength of the cornea, although no correlations with the duration of illness or attack frequency could be determined.

  7. Corneal Biomechanics in Ectatic Diseases: Refractive Surgery Implications.

    Science.gov (United States)

    Ambrósio, Renato; Correia, Fernando Faria; Lopes, Bernardo; Salomão, Marcella Q; Luz, Allan; Dawson, Daniel G; Elsheikh, Ahmed; Vinciguerra, Riccardo; Vinciguerra, Paolo; Roberts, Cynthia J

    2017-01-01

    Ectasia development occurs due to a chronic corneal biomechanical decompensation or weakness, resulting in stromal thinning and corneal protrusion. This leads to corneal steepening, increase in astigmatism, and irregularity. In corneal refractive surgery, the detection of mild forms of ectasia pre-operatively is essential to avoid post-operative progressive ectasia, which also depends on the impact of the procedure on the cornea. The advent of 3D tomography is proven as a significant advancement to further characterize corneal shape beyond front surface topography, which is still relevant. While screening tests for ectasia had been limited to corneal shape (geometry) assessment, clinical biomechanical assessment has been possible since the introduction of the Ocular Response Analyzer (Reichert Ophthalmic Instruments, Buffalo, USA) in 2005 and the Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany) in 2010. Direct clinical biomechanical evaluation is recognized as paramount, especially in detection of mild ectatic cases and characterization of the susceptibility for ectasia progression for any cornea. The purpose of this review is to describe the current state of clinical evaluation of corneal biomechanics, focusing on the most recent advances of commercially available instruments and also on future developments, such as Brillouin microscopy.

  8. Microkeratome-assisted corneal tattooing: a case report.

    Science.gov (United States)

    Fogla, Rajesh; Gupta, Arvind; Indumathy, T R

    2010-04-01

    The purpose of this study was to report a new technique of microkeratome-assisted corneal tattooing for cosmetic improvement in a young female patient with adherent leucoma. The para-axial adherent leucoma had resulted from penetrating corneal injury sustained at the age of 2 years. A nasal hinged partial corneal flap of 140 μm thickness was raised using the microkeratome. The flap extended to just beyond the medial margin of the leucoma. Organic dye powder was spread on the stromal bed over the leucomatous scar as well as on the undersurface of the corneal flap corresponding to the area of opacity. The flap was then repositioned and a bandage contact lens placed. The staining dye powder completely concealed the leucomatous opacity with good cosmesis and patient satisfaction. Corneal topography and best-corrected visual acuity remained unchanged at last follow up of 9 months. Microkeratome-assisted corneal tattooing appears to be a safe, effective, and precise method of corneal tattooing.

  9. Correlating corneal arcus with atherosclerosis in familial hypercholesterolemia

    Directory of Open Access Journals (Sweden)

    Zech Loren A

    2008-03-01

    Full Text Available Abstract Background A relationship between corneal arcus and atherosclerosis has long been suspected but is controversial. The homozygous familial hypercholesterolemia patients in this study present a unique opportunity to assess this issue. They have both advanced atherosclerosis and corneal arcus. Methods This is a cross-sectional study of 17 patients homozygous for familial hypercholesterolemia presenting to the Clinical Center of the National Institutes of Health. Plasma lipoproteins, circumferential extent of arcus, thoracic aorta and coronary calcific atherosclerosis score, and Achilles tendon width were measured at the National Institutes of Health. Results Patients with corneal arcus had higher scores for calcific atherosclerosis (mean 2865 compared to 412, cholesterol-year score (mean 11830 mg-yr/dl compared to 5707 mg-yr/dl, and Achilles tendon width (mean 2.54 cm compared to 1.41 cm than those without. Corneal arcus and Achilles tendon width were strongly correlated and predictive of each other. Although corneal arcus was correlated with calcific atherosclerosis (r = 0.67; p = 0.004, it was not as highly correlated as was the Achilles tendon width (r = 0.855; p Conclusion Corneal arcus reflects widespread tissue lipid deposition and is correlated with both calcific atherosclerosis and xanthomatosis in these patients. Patients with more severe arcus tend to have more severe calcific atherosclerosis. Corneal arcus is not as good an indicator of calcific atherosclerosis as Achilles tendon thickness, but its presence suggests increased atherosclerosis in these hypercholesterolemic patients.

  10. Preparation and Biomechanical Properties of an Acellular Porcine Corneal Stroma.

    Science.gov (United States)

    Li, Qing; Wang, Hongmei; Dai, Zhenye; Cao, Yichen; Jin, Chuanyu

    2017-11-01

    To construct an acellular porcine corneal stroma (aPCS) as a human corneal stroma alternative and to further explore its biomechanical properties. A combination of DNA-RNA enzymes and ultrasound technology was used to strip the native porcine corneal cells. The microstructure of aPCS was observed by H&E staining, DAPI staining, and α-Gal tests. The mechanical properties were detected by a tension machine. Cytotoxicity of aPCS was measured by the MTT assay. The subcutaneous embedding experiment in rats was also used to detect immunity and degradation. The aPCS was transplanted into the rabbit cornea by lamellar keratoplasty, general observations were made at 3 days, 1 week, 1 month, and 3 months after implantation, respectively. The microstructure and mechanical properties of aPCS were not damaged during the decellularization process. The aPCS extracts had no significant cytotoxicity on human corneal stroma cells. Moreover, the subcutaneous embedding experiment in rats demonstrated that aPCS could not be degraded and induced no immune reaction in and around the transplanted discs. More important is that the aPCS reconstructed normal corneal stroma and maintained corneal transparency and thickness, with almost no neovascularization and inflammation at 3 months after surgery. The aPCS prepared in this study had good biocompatibility, safety, and low antigenicity, which has great potential for corneal disease treatment.

  11. Impact of Hydration Media on Ex Vivo Corneal Elasticity Measurements.

    Science.gov (United States)

    Dias, Janice; Ziebarth, Noël M

    2015-09-01

    To determine the effect of hydration media on ex vivo corneal elasticity. Experiments were conducted on 40 porcine eyes retrieved from an abattoir (10 eyes each for phosphate-buffered saline (PBS), balanced salt solution, Optisol, 15% dextran). The epithelium was removed, and the cornea was excised with an intact scleral rim and placed in 20% dextran overnight to restore its physiological thickness. For each hydration media, corneas were evenly divided into two groups: one with an intact scleral rim and the other without. Corneas were mounted onto a custom chamber and immersed in a hydration medium for elasticity testing. Although in each medium, corneal elasticity measurements were performed for 2 hr: at 5-min intervals for the first 30 min and then 15-min intervals for the remaining 90 min. Elasticity testing was performed using nanoindentation with spherical indenters, and Young modulus was calculated using the Hertz model. Thickness measurements were taken before and after elasticity testing. The percentage change in corneal thickness and elasticity was calculated for each hydration media group. Balanced salt solution, PBS, and Optisol showed an increase in thickness and Young moduli for corneas with and without an intact scleral rim. Fifteen percent dextran exhibited a dehydrating effect on corneal thickness and provided stable maintenance of corneal elasticity for both groups. Hydration media affects the stability of corneal thickness and elasticity measurements over time. Fifteen percent dextran was most effective in maintaining corneal hydration and elasticity, followed by Optisol.

  12. Corneal Biomechanics in Ectatic Diseases: Refractive Surgery Implications

    Science.gov (United States)

    Ambrósio, Jr, Renato; Correia, Fernando Faria; Lopes, Bernardo; Salomão, Marcella Q.; Luz, Allan; Dawson, Daniel G.; Elsheikh, Ahmed; Vinciguerra, Riccardo; Vinciguerra, Paolo; Roberts, Cynthia J.

    2017-01-01

    Background: Ectasia development occurs due to a chronic corneal biomechanical decompensation or weakness, resulting in stromal thinning and corneal protrusion. This leads to corneal steepening, increase in astigmatism, and irregularity. In corneal refractive surgery, the detection of mild forms of ectasia pre-operatively is essential to avoid post-operative progressive ectasia, which also depends on the impact of the procedure on the cornea. Method: The advent of 3D tomography is proven as a significant advancement to further characterize corneal shape beyond front surface topography, which is still relevant. While screening tests for ectasia had been limited to corneal shape (geometry) assessment, clinical biomechanical assessment has been possible since the introduction of the Ocular Response Analyzer (Reichert Ophthalmic Instruments, Buffalo, USA) in 2005 and the Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany) in 2010. Direct clinical biomechanical evaluation is recognized as paramount, especially in detection of mild ectatic cases and characterization of the susceptibility for ectasia progression for any cornea. Conclusions: The purpose of this review is to describe the current state of clinical evaluation of corneal biomechanics, focusing on the most recent advances of commercially available instruments and also on future developments, such as Brillouin microscopy. PMID:28932334

  13. Evaluation of corneal biomechanical properties following penetrating keratoplasty using ocular response analyzer

    OpenAIRE

    Vanathi Murugesan; Ravi Bypareddy; Mahesh Kumar; Dada Tanuj; Panda Anita

    2014-01-01

    Purpose: To evaluate corneal biomechanical properties in eyes that has undergone penetrating keratoplasty (PK). Materials and Methods: Retrospective observational study in a tertiary care centre. Data recorded included ocular response analyzer (ORA) values of normal and post-keratoplasty eyes [corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg), and cornea-compensated intraocular pressure (IOPcc)], corneal topography, and central corneal t...

  14. Combined effects of interleukin-1? and cyclic stretching on metalloproteinase expression in corneal fibroblasts in vitro

    OpenAIRE

    Feng, Pengfei; Li, Xiaona; Chen, Weiyi; Liu, Chengxing; Rong, Shuo; Wang, Xiaojun; Du, Genlai

    2016-01-01

    Background Corneal tensile strain increases if the cornea becomes thin or if intraocular pressure increases. However, the effects of mechanical stress on extracellular matrix (ECM) remodelling in the corneal repair process and the corneal anomalies are unknown. Methods In this study, the combined effects of interleukin-1? (IL-1?) on matrix metalloproteinases (MMPs) in corneal fibroblasts under cyclic stretching were investigated in vitro. Cultured rabbit corneal fibroblasts were subjected to ...

  15. Impact of corneal aberrations on through-focus image quality of presbyopia-correcting intraocular lenses using an adaptive optics bench system.

    Science.gov (United States)

    Zheleznyak, Len; Kim, Myoung Joon; MacRae, Scott; Yoon, Geunyoung

    2012-10-01

    To measure the impact of corneal aberrations on the through-focus image quality of presbyopia-correcting intraocular lenses (IOLs) using an adaptive optics IOL metrology system. Flaum Eye Institute, University of Rochester, Rochester, New York, USA. Experimental study. An adaptive optics IOL metrology system comprising a model eye, wavefront sensor, deformable mirror, and an image-capturing device acquired through-focus images of a letter chart with 3.0 mm and 5.0 mm pupil diameters. The system was used to induce corneal astigmatism and higher-order aberrations (HOAs) in previously measured pseudophakic presbyopic eyes. A single-optic accommodating IOL (Crystalens HD (HD500), an apodized (Restor +3.0 diopter [D] SN6AD1) and full-aperture (Tecnis ZM900) diffractive multifocal IOL, and a monofocal IOL (Acrysof SN60AT) were evaluated. Image quality was quantified using the correlation-coefficient image-quality metric. The single-optic accommodating IOL and monofocal IOL performed similarly; however, with a 3.0 mm pupil, the former had better intermediate (1.50 D) image quality. The multifocal IOLs had bimodal through-focus image quality trends. Corneal astigmatism reduced through-focus image quality and depth of focus with all IOLs; however, the multifocal IOLs had the most severe decline in depth of focus. Ocular spherical aberration had the strongest impact on image quality when typical pseudophakic corneal HOAs were present. The uncorrected corneal astigmatism and HOAs in pseudophakic eyes significantly affected through-focus performance of presbyopia-correcting IOLs. Although multifocal IOLs significantly increased depth of focus, this benefit diminished when more than 0.75 D astigmatism remained uncorrected. Residual ocular spherical aberration had a significant effect on image quality in the presence of other corneal HOAs. Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  16. Using corneal topography design personalized cataract surgery programs

    Directory of Open Access Journals (Sweden)

    Jin-Ou Huang

    2014-08-01

    Full Text Available AIM:To investigate how to design personalized cataract surgery programs to achieve surgical correction of preoperative corneal astigmatism with surgical astigmatism under the guidance of corneal topography, improve postoperative visual quality and reduce the cost of treatment. METHODS: Totally 202 cases(226 eyescataract patients were divided into randomized treatment group and individualized treatment group. According to the method and location of the incision, randomized treatment group were divided into 8 groups. Surgical astigmatism after different incision were calculated with the use of preoperative and postoperative corneal astigmatism through vector analysis method. Individualized treatment groups were designed personably for surgical method with reference of every surgically induced astigmatism, the surgical method chooses the type of surgical incision based on close link between preoperative corneal astigmatism and surgically induced astigmatism, and the incision was located in the steep meridian. The postoperative corneal astigmatism of individualized treatment group was observed. RESULTS: Postoperative corneal astigmatism of individualized treatment group were lower than that of 3.0mm clear corneal tunnel incision in the randomized treatment group, there were statistically significance difference, while with 3.0mm sclera tunnel incision group there were no statistically significance difference. After 55.8% of patients with the use of individualized surgical plan could undergo the operation of extracapsular cataract extraction with relatively low cost and rigid intraocular lens implantation, the per capita cost of treatment could be reduced. CONCLUSION: Personalized cataract surgery programs are designed to achieve surgical correction of preoperative corneal astigmatism under the use of corneal topography, improve postoperative visual quality and reduce the cost of treatment.

  17. Does severity of dermatochalasis in aging affect corneal biomechanical properties?

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    Atalay K

    2016-05-01

    Full Text Available Kurşat Atalay, Ceren Gurez, Ahmet Kirgiz, Kubra Serefoglu Cabuk Department of Ophthalmology, Bagcilar Training and Research Hospital, Istanbul, Turkey Purpose: The aim of this study was to investigate the possibility of a relationship between corneal biomechanical properties and different grades of dermatochalasis.Patients and methods: Patients were assigned to four groups according to the severity of their dermatochalasis: normal (Group 1, mild (Group 2, moderate (Group 3, and severe (Group 4. An Ocular Response Analyzer device was used to measure corneal hysteresis (CH, corneal resistance factor (CRF, and corneal-compensated intraocular pressure (IOPcc.Results: We found no significant differences in the mean values of the CH, CRF, and IOPcc of all groups (P=0.75, P=0.93, and P=0.11, respectively. However, CH and IOPcc were negatively correlated in Group 1, Group 2, and Group 3 patients (P=0.013, r=−0.49; P=0.015, r=−0.52; and P=0.011, r=−0.47, respectively, but this correlation was not apparent in the Group 4 patients (P=0.57, r=0.12. CRF and IOPcc were correlated, but only in Group 4 (P=0.001, r=0.66.Conclusion: Severe dermatochalasis was associated with altered corneal biomechanical properties. Some of the important visual consequences of dermatochalasis and related diseases (such as floppy eyelid syndrome can be understood by considering corneal biomechanical alterations. Keywords: cornea, dermatochalasis, corneal hysteresis, corneal resistance factor, corneal biomechanical properties

  18. Corneal biomechanical properties of patients with pseudoexfoliation syndrome.

    Science.gov (United States)

    Yenerel, Nursal Melda; Gorgun, Ebru; Kucumen, Raciha Beril; Oral, Deniz; Dinc, Umut Asl; Ciftci, Ferda

    2011-09-01

    To assess the corneal biomechanical properties of patients with pseudoexfoliation syndrome (PEX syndrome). Fifty-two eyes of 52 patients (27 unilateral and 25 bilateral) and 42 eyes of 42 age-matched control subjects were enrolled in the study. Metrics of corneal biomechanical properties, including corneal hysteresis (CH) and corneal resistance factor (CRF), were measured with the ocular response analyzer (ORA). The ORA also determined the values of Goldmann-correlated intraocular pressure and corneal-compensated intraocular pressure. Central corneal thickness (CCT) was measured by the ORA integrated handheld ultrasonic pachymeter. The values recorded by the ORA were compared between eyes with PEX syndrome and those without PEX syndrome. Eyes with unilateral PEX syndrome and fellow eyes without PEX syndrome were also compared. The mean CH and CRF of all eyes with PEX syndrome were significantly lower than those of control eyes (P corneal-compensated intraocular pressure nor Goldmann-correlated intraocular pressure showed a statistically significant difference in both the groups. Mean CCT values also did not show significant difference. Comparison of the unilateral eyes with PEX syndrome with the apparently normal fellow eyes revealed no significant difference between the mean CCT, mean CH, and mean CRF values (P > 0.05). However, the mean corneal-compensated intraocular pressure and Goldmann-correlated intraocular pressure were relatively higher in the PEX syndrome eye (P 0.05). The CH and CRF decrease in both unilateral and bilateral PEX syndrome suggested that PEX syndrome has a weakening effect on corneal biomechanical properties. Moreover, in subjects with clinically unilateral PEX syndrome, these properties were closer to eyes with PEX syndrome than to normal control eyes.

  19. Effect of Corneal Thickness on the Penetration of Topical Vancomycin.

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    Spierer, Oriel; Regenbogen, Michael; Lazar, Moshe; Yatziv, Yossi

    2015-10-01

    To study the influence of corneal thickness on intraocular penetration of topical ophthalmic drops, using vancomycin 50 mg/mL drops as a model. The study included 58 eyes of 58 patients undergoing phacoemulsification cataract extraction. The central corneal thickness was measured by ultrasonic pachymetry on the day of surgery. Thirty minutes before the surgery, one drop of topical vancomycin 50 mg/mL was instilled three times with 10-minute intervals: 30 minutes, 20 minutes, and 10 minutes before the surgery. At the beginning of surgery, a small specimen of aqueous humor was aspirated and sent to the laboratory for measurement of drug concentration to determine the effect of corneal thickness on vancomycin concentration in the anterior chamber. There was insufficient amount of aqueous humor for analysis in 9 samples, leaving a total of 49 samples. The mean central corneal thickness was 539.7 (±39.5) μm (range, 458 to 635 μm). The mean vancomycin concentration in the anterior chamber was 0.220 (±0.209) μg/mL. There was no significant association between vancomycin concentration and corneal thickness (r = -0.07, p = 0.62, Pearson correlation). When patients were divided into three groups based on the mean (±1 SD) central corneal thickness, no significant differences in vancomycin concentrations (in micrograms per milliliter) were encountered: 0.267 (±0.247) (for corneal thickness thickness of 500.2 to 579.2 μm), and 0.200 (±0.160) (for corneal thickness >579.2 μm) (p = 0.73, analysis of variance). Corneal thickness does not influence the penetration of topically applied vancomycin into the anterior chamber.

  20. Use of soft contact lenses in an eye casualty department for the primary treatment of traumatic corneal abrasions.

    Science.gov (United States)

    Acheson, J F; Joseph, J; Spalton, D J

    1987-01-01

    We have assessed the role of bandage contact lenses in the primary treatment of traumatic corneal abrasions. Patients treated with bandage lenses healed more quickly (0.05 greater than p greater than 0.02) and with less discomfort (0.05 greater than p greater than 0.02) than those treated traditionally, with the added advantage of maintaining vision during treatment. Resterilisation of contact lenses reduces the cost and makes the treatment economically viable. Large diameter lenses were fitted satisfactorily without the use of keratometry. PMID:3555607