Uveal effusion syndrome: a case report.

BACKGROUND: This case report is applicable to the field of ophthalmology because there is a paucity of medical literature related to the clinical presentation, diagnosis, and management of uveal effusion syndrome. This is an urgent concern because there are severe complications associated with this disease, including non-rhegmatogenous retinal detachment, angle closure glaucoma, and possible blindness. This report will fill clinical knowledge gaps using a patient example. CASE PRESENTATION: A 68-year-old white male with multiple cardiovascular risk factors initially presented to the Eye Institute Urgent Care Clinic with new onset visual symptoms, including eye pain, eye lid swelling, redness, and tearing of his left eye. He had experienced a foreign body sensation in the left eye and bilateral floaters weeks prior to his presentation. The patient was examined, and vision was 20/30 in both eyes, and intraocular pressure was 46 in the right eye and 36 in the left eye. After initial assessment, including compression gonioscopy, intermittent angle closure glaucoma was suspected. He received oral diamox 500 mg, one drop of alphagan in both eyes, one drop of latanoprost in both eyes, one drop of dorzolamide in both eyes, and one drop of 2% pilocarpine in both eyes. There was only slight response in intraocular pressure. Owing to the bilateral angle closure, he underwent laser peripheral iridotomy to decrease intraocular pressure and open the angle that was found closed on gonioscopy. The patient was discharged on oral and topical glaucoma drops and scheduled for the glaucoma clinic. When he presented for follow-up in the glaucoma clinic, he was evaluated and noted to have bilateral narrow angles and intraocular pressure in the mid-twenties. A brightness scan (B-scan) was performed and was noted to have bilateral choroidal effusions, confirmed by Optos fundus photos. He was started on prednisone at 60 mg once per day (QD) with taper, continuation of oral and topical glaucoma medications, and a retina evaluation. Evaluation with a retina specialist showed resolving choroidal effusion in the left eye. He continued the prednisone taper as well as glaucoma drops as prescribed. Follow-up in the glaucoma clinic revealed a grade 3 open angle. He continued the prednisone taper, cosopt twice per day in both eyes, and discontinued brimonidine. The magnetic resonance imaging (MRI) that was performed showed results that were remarkable. No hemorrhage or mass was present. Follow-up with the retina specialist found that the choroidal effusions had resolved completely. CONCLUSION: This case report emphasizes the value in early detection, keen diagnostic evaluation, and cross-collaboration between multiple ophthalmology specialists to optimize healthcare outcomes for patients with uveal effusion syndrome.

Thickness of anterior sclera and corneal layers in systemic sclerosis.

PURPOSE: To evaluate the thickness of anterior sclera and corneal layers in patients with systemic sclerosis. METHODS: The present cross-sectional study included 41 patients with systemic sclerosis and 41 age- and gender-matched healthy controls. The study and control groups were compared in terms of the thickness of anterior sclera, corneal epithelium, Bowman's layer, corneal stroma, and Descemet's membrane-endothelium complex. The thickness measurements were obtained using the anterior segment module of spectral-domain optical coherence tomography. RESULTS: The thickness of anterior sclera, corneal epithelium, Bowman's layer, and Descemet's membrane-endothelium complex were similar in the patients with systemic sclerosis and healthy controls (P > 0.05). Total corneal thickness at the apex was 511.1 ± 33.5 µm in the systemic sclerosis group and 528.4 ± 29.5 µm in the control group (P = 0.015). The corneal stroma was thinner in the systemic sclerosis patients compared to the healthy controls (P = 0.02). CONCLUSIONS: The corneal stroma was thinner in the patients with systemic sclerosis compared to that of healthy controls, while the thickness of the anterior sclera was similar in both groups.

[Structural and functional features of the eye in Marfan syndrome. Report 1. Changes in the fibrous tunic of the eye]. / Strukturno-funktsional'nye osobennosti glaza pri sindrome Marfana. Soobshchenie 1. Izmeneniya fibroznoi obolochki.

Marfan syndrome (MS) is an orphan hereditary connective tissue disease associated with a mutation in the FBN1 gene, which pathological manifestations are characterized by polysystemic involvement. The fibrillin-1 protein is an integral component of the sclera and cornea of the eye, and in MS its structure is distrubed. PURPOSE: This study assesses potential structural and functional changes in the cornea and sclera of a patient with MS. MATERIAL AND METHODS: Two groups were formed, comparable in the axial length of the eye and age: the main group - 19 patients (38 eyes) with a verified diagnosis of MS, and the control group - 24 patients (48 eyes) with myopia of varying degrees. The results obtained from MS patients were analyzed depending on the absence or presence of ectopia lentis. In addition to measuring the basic ophthalmological parameters (refraction, axial length, visual acuity), topographic keratometry, anterior segment optical coherence tomography, and ocular response analyzer were used for structural and functional assessment of the cornea and sclera. RESULTS: In MS there was a statistically significant increase in the radius of curvature and a decrease in corneal refraction in the central zone compared to the control group. There were no significant differences in central corneal thickness, but there was a significant decrease in the thickness of the sclera in the limbal zone compared to the control group. There were no statistically significant changes in corneal hysteresis and corneal resistance factor in MS. CONCLUSION: This study confirmed the previously obtained data on the tendency of the optical power to reliably decrease in MS (flattening of the cornea). This symptom can be considered as a compensatory factor affecting clinical refraction, while the decrease in the thickness of the sclera - as the main reason for aaxial length elongation in MS. There were no clear patterns of dependence of the changes in the cornea and sclera analyzed in this study on the presence or absence of ectopia lentis. Changes in the lens, perhaps, should be regarded only as one of the potential components of the ocular symptom complex in MS.

Evaluation of the effect of intravitreal injections on corneal epithelial, scleral and limbal region changes in diabetic retinopathy by AS-OCT.

PURPOSE: The aim of the study is to evaluate the effects of diabetic retinopathy and intravitreal injections on the corneal, limbal and scleral areas. METHODS: Patients with diabetes mellitus at different diagnosis and treatment levels were compared among themselves and with the control group in terms of corneal, limbal and scleral aspects with the help of anterior segment optical coherence tomography. In addition, clinical tests such as tear break-up time, Schirmer test-I and ocular surface disease index questionnaire were applied to the patients and the difference between the groups was investigated. RESULTS: When the groups were examined in terms of BUT, SCH-I and OSDI, there was a statistically significant difference between control group and diabetic group(p < 0.05). In the limbal region, all measurements are higher than in patients with diabetic eye involvement. Thinning was detected in the scleral area with intravitreal injection (p < 0.05). CONCLUSION: It should be known that DM may cause undesirable changes in the limbal region, and the importance of non-invasive detection with AS-OCT should not be forgotten. Since intravitreal injections for DME cause thinning of the sclera, it can cause various complications, and it may be recommended to change the quadrant in repetitive injection applications.

Scleral Grafts in Ophthalmic Surgery. A Review.

AIM: To summarize the history and current trends in the use of scleral grafts in ophthalmology. MATERIALS AND METHODS: We conducted a review of the literature through the MEDLINE and Cochrane Library databases. The search terms were "sclera", "graft", and "surgery". The search resulted in 1596 articles, of which we evaluated 192 as relevant. The relevant articles were sorted chronologically and according to the method of using scleral grafts, which enabled the development of a review article. RESULTS: The sclera has been routinely used in ophthalmology since the 1950s in many different indications. Some of these indications have become practically obsolete over time (for example, use in the surgical management of retinal detachment), but a large number still find application today (especially use in glaucoma or oculoplastic surgery, or as a patch for a defect in the sclera or cornea). CONCLUSION: Even though allogeneic sclera is currently used less frequently in ophthalmology compared to other tissue banking products and the range of its indications has partially narrowed, it remains a useful material due to its availability and properties.

Morphometric Assessment of Sclera and Ciliary Body in Patients with Noninfectious Anterior Scleritis: A Quantitative Study Using Ultrasound Biomicroscopy.

BACKGROUND: At present, the severity and grade of anterior scleritis are judged mainly based on the area and location of involvement, whether there is necrosis, etc. Quantitative measurement of sclera and surrounding tissues will help to accurately assess the severity of scleritis and provide quantitative indicators for the choice of treatment. METHODS: We retrospectively analyzed the thickness of sclera and ciliary bodies detected by ultrasound biological microscopy (UBM) in noninfectious anterior scleritis patients who subsequently were treated with topical or systemic treatment, and visited our hospital from March 2014 to March 2021. Age- and sex-matched normal individuals were used as controls. RESULTS: A total of 185 patients (50 males and 135 females) with noninfectious anterior scleritis and 84 (31 males and 53 females) controls were included. In patients with noninfectious scleritis, the thickness of sclera and the ciliary body were significantly greater than those in the control group (p < 0.05). Before treatment, the thickness of sclera and the ciliary body in systemic treatment group was significantly higher than that in topical treatment group (p < 0.05). After treatment, both thicknesses of sclera and the ciliary body decreased significantly (p < 0.05). The ratio of ciliary body thickness from the site of inflammation to the normal position was significantly higher in the systemic treatment group than in the topical treatment group. CONCLUSIONS: UBM quantitatively shows a decrease in AST/CBT in patients with anterior scleritis after treatment. The ratio of ciliary body thickness at the site of information to that at the normal position may be a reference for the choice of treatment.

Scleral remodeling during myopia development in mice eyes: a potential role of thrombospondin-1.

BACKGROUND: Scleral extracellular matrix (ECM) remodeling plays a crucial role in the development of myopia, particularly in ocular axial elongation. Thrombospondin-1 (THBS1), also known as TSP-1, is a significant cellular protein involved in matrix remodeling in various tissues. However, the specific role of THBS1 in myopia development remains unclear. METHOD: We employed the HumanNet database to predict genes related to myopic sclera remodeling, followed by screening and visualization of the predicted genes using bioinformatics tools. To investigate the potential target gene Thbs1, we utilized lens-induced myopia models in male C57BL/6J mice and performed Western blot analysis to detect the expression level of scleral THBS1 during myopia development. Additionally, we evaluated the effects of scleral THBS1 knockdown on myopia development through AAV sub-Tenon's injection. The refractive status and axial length were measured using a refractometer and SD-OCT system. RESULTS: During lens-induced myopia, THBS1 protein expression in the sclera was downregulated, particularly in the early stages of myopia induction. Moreover, the mice in the THBS1 knockdown group exhibited alterations in myopia development in both refraction and axial length changed compared to the control group. Western blotting analysis confirmed the effectiveness of AAV-mediated knockdown, demonstrating a decrease in COLA1 expression and an increase in MMP9 levels in the sclera. CONCLUSION: Our findings indicate that sclera THBS1 levels decreased during myopia development and subsequent THBS1 knockdown showed a decrease in scleral COLA1 expression. Taken together, these results suggest that THBS1 plays a role in maintaining the homeostasis of scleral extracellular matrix, and the reduction of THBS1 may promote the remodeling process and then affect ocular axial elongation during myopia progression.

Metabolomic profiling of ocular tissues in rabbit myopia: Uncovering differential metabolites and pathways.

To investigate the metabolic difference among tissue layers of the rabbits' eye during the development of myopia using metabolomic techniques and explore any metabolic links or cascades within the ocular wall. Ultra Performance Liquid Chromatography - Mass Spectrometry (UPLC-MS) was utilized for untargeted metabolite screening (UMS) to identify the significant differential metabolites produced between myopia (MY) and control (CT) (horizontal). Subsequently, we compared those key metabolites among tissues (Sclera, Choroid, Retina) of MY for distribution and variation (longitudinal). A total of 6285 metabolites were detected in the three tissues. The differential metabolites were screened and the metabolic pathways of these metabolites in each myopic tissue were labeled, including tryptophan and its metabolites, pyruvate, taurine, caffeine metabolites, as well as neurotransmitters like glutamate and dopamine. Our study suggests that multiple metabolic pathways or different metabolites under the same pathway, might act on different parts of the eyeball and contribute to the occurrence and development of myopia by affecting the energy supply to the ocular tissues, preventing antioxidant stress, affecting scleral collagen synthesis, and regulating various neurotransmitters mutually.

Automatic segmentation of layers in chorio-retinal complex using Graph-based method for ultra-speed 1.7 MHz wide field swept source FDML optical coherence tomography.

The posterior segment of the human eye complex contains two discrete microstructure and vasculature network systems, namely, the retina and choroid. We present a single segmentation framework technique for segmenting the entire layers present in the chorio-retinal complex of the human eye using optical coherence tomography (OCT) images. This automatic program is based on the graph theory method. This single program is capable of segmenting seven layers of the retina and choroid scleral interface. The graph theory was utilized to find the probability matrix and subsequent boundaries of different layers. The program was also implemented to segment angiographic maps of different chorio-retinal layers using "segmentation matrices." The method was tested and successfully validated on OCT images from six normal human eyes as well as eyes with non-exudative age-related macular degeneration (AMD). The thickness of microstructure and microvasculature for different layers located in the chorio-retinal segment of the eye was also generated and compared. A decent efficiency in terms of processing time, sensitivity, and accuracy was observed compared to the manual segmentation and other existing methods. The proposed method automatically segments whole OCT images of chorio-retinal complex with augmented probability maps generation in OCT volume dataset. We have also evaluated the segmentation results using quantitative metrics such as Dice coefficient and Hausdorff distance This method realizes a mean descent Dice similarity coefficient (DSC) value of 0.82 (range, 0.816-0.864) for RPE and CSI layer.

Regional differences in electroactive response of the sclera.

The sclera exhibits mechanical response when subjected to an external electric stimulation. The scleral electroactive response is a function of its charge density, mechanical properties, thickness, and strength of the applied electric voltage. The primary objective of the present work was to investigate the regional differences in the electroactive response of porcine sclera. To this end, we cut scleral strips in meridional directions from superior-temporal, superior-nasal, inferior-temporal, and inferior-nasal quadrants. In addition, we excised samples circumferentially from the posterior, equatorial, and anterior regions. The electroactive bending response of these samples was measured under 10 and 15 V in 0.15 M NaCl solution. The meridional samples were tested under two different configurations by clamping them either from their anterior or posterior end. It was observed that the scleral electroactive deformation increased with increasing the the electric voltage. Furthermore, regardless of the region from which meridional strips were excised, their electroactive response was considerably larger when they were clamped from their anterior end. Unlike meridional strips, the electroactive response of circumferential samples was significantly dependent on the location, that is, the average maximum bending angle of posterior samples was significantly larger than that of equatorial and anterior strips. The regionally different electroactive bending response of the sclera was discussed in terms of the variation in its biochemical and biomechanical properties throughout the eyeball.

Evaluación del músculo ciliar y del grosor escleral anterior en miopes altos mediante tomografía de coherencia óptica / Assessment of the ciliary muscle and scleral anterior thickness in high myopia by optical coherence tomography

Propósito: Evaluar las dimensiones del músculo ciliar (MC) y del grosor escleral anterior (AST) in vivo en miopes altos mediante tomografía de coherencia óptica de fuente de barrido (SS-OCT) y comparar con sujetos emétropes e hipermétropes.MétodosEstudio transversal en el que se incluyeron 34 miopes altos (≥−6dioptrías [D]), 90 emétropes (−1 a +1D) y 38 hipermétropes (≥+3,5D). Se midieron el grosor del MC (CMT) y el AST en los cuadrantes temporal y nasal a 1, 2 y 3mm del espolón escleral utilizando la SS-OCT. Además, se evaluó la longitud del MC (CML).ResultadosLas dimensiones tanto del CML como del CMT en cualquiera de sus puntos de medida fueron mayores en miopes altos y en emétropes que en hipermétropes, tanto en el cuadrante nasal como en el temporal (p<0,001). Sin embargo, no existieron diferencias entre miopes magnos y emétropes para ninguno de los parámetros (p≥0,076), salvo para el CMT a 3mm en temporal (p<0,001). No existieron diferencias en el AST entre miopes altos, emétropes e hipermétropes, en ninguno de los puntos de medida ni cuadrantes estudiados (p>0,05).ConclusionesLa SS-OCT permite medir el MC in vivo, no observándose diferencias en sus dimensiones entre miopes altos y emétropes, pero sí que fueron menores en hipermétropes. En la medida de la esclera anterior no se observaron diferencias entre los tres grupos analizados según la refracción. (AU)

Purpose: To assess ciliary muscle (CM) and anterior scleral thickness (AST) dimensions in vivo in high myopia using swept-source optical coherence tomography (SS-OCT) and to compare with emmetropic and hyperopic subjects.MethodsCross-sectional study that included 34 high myopic patients (≥−6 diopters [D]), 90 emmetropes (−1 to +1D) and 38 hyperopic patients (≥+3.5D). CM thickness (CMT) and AST were measured in the temporal and nasal quadrants at 1, 2, and 3mm from the scleral spur using SS-OCT. In addition, the length of the CM (CML) was evaluated.ResultsThe dimensions of the CML and the CMT at any of their measurement points were greater in high myopes and emmetropes than in hyperopes, both in the nasal and temporal quadrants (P<.001). However, there were no differences between high myopes and emmetropes for any of the parameters (P≥.076) except for the CMT at 3mm in the temporal quadrant (P<.001). There were no differences in the AST between high myopes, emmetropes and hyperopes, in any of the measurement points or quadrants studied (P>.05).ConclusionsThe SS-OCT allows to measure the CM in vivo, not observing differences in its dimensions between high myopes and emmetropes, but they were smaller in hyperopes. In the measurement of the anterior sclera, no differences were observed between the three groups analyzed according to refraction. (AU)

Orthokeratology effect on the corneoscleral profile: Beyond the bull's eye.

PURPOSE: To assess the impact of 3 months of orthokeratology (ortho-k) contact lenses (CLs) for myopia correction on the corneoscleral profile, as changes in scleral geometry could serve as indirect evidence of alteration in the corneal biomechanical properties. METHODS: Twenty subjects (40 eyes) were recruited to wear ortho-k lenses overnight; however, after discontinuation (two CL fractures, one under-correction and two non-serious adverse events), 16 subjects (31 eyes) finished a 3-month follow-up. Corneoscleral topographies were acquired using the Eye Surface Profiler (ESP) system before and after 3 months of lens wear. Steep (SimKs) and flat (SimKf) simulated keratometry and scleral sagittal height measurements for 13-, 14- and 15-mm chord lengths were automatically calculated by the ESP software. Additionally, sagittal height and slope were calculated in polar format from 21 radii (0-10 mm from the corneal apex) at 12 angles (0-330°). Linear mixed models were fitted to determine the differences between visits. RESULTS: SimKs and SimKf were increased significantly (p ≤ 0.02). The sagittal height in polar format increased significantly (p = 0.046) at a radius of 2.5 mm for 150°, 180°, 210° and 240° orientations and at a radius of 3.0 mm for 210°. Additionally, the slope in polar format significantly decreased (p ≤ 0.04) at radii ranges of 0.0-0.5, 0.5-1.0 and 1.0-1.5 mm for multiple angles and at a radii range of 5.0-5.5 mm for 90°. It also increased significantly (p ≤ 0.045) at a radii range of 1.5-2.0 mm for 30° and at radii ranges of 2.0-2.5, 2.5-3.0 and 3.0-3.5 mm for multiple angles. No significant changes were found for any parameter measured from the scleral area. CONCLUSIONS: Three months of overnight ortho-k lens wear changed the central and mid-peripheral corneal geometry as expected, maintaining the peripheral cornea and the surrounding sclera stability.

Biallelic novel variants in ZNF469 causing Brittle Cornea Syndrome 1: a detailed report of an Indian patient.

BACKGROUND: Variations in ZNF469 have been associated with Brittle Cornea Syndrome that presents with bluish sclera, loss of vision after trivial trauma, arachnodactyly, and joint laxity. MATERIALS AND METHODS: Detailed medical and family history, physical examination, and molecular analysis. RESULTS: A 21-year-old female presented with bluish discoloration of sclera, diminution of vision following trivial trauma in childhood along with hearing loss and systemic features of arachnodactyly and joint laxity. Clinical diagnosis of brittle cornea syndrome was made which was molecularly proven using next-generation sequencing which identified compound heterozygosity in ZNF469 for pathogenic and likely pathogenic nonsense variants. One variant namely NM_001367624.2:c.5882dup was identified in the exon 3 which was novel and classified as likely pathogenic according to American College of Medical Genetics (ACMG) criteria for variant classification. Another variant NM_001367624.2:c.8992C>T in the exon 2 was classified as pathogenic for Brittle Cornea Syndrome 1. CONCLUSIONS: The report adds to the allelic heterogeneity in ZNF469 causative of Brittle Cornea Syndrome 1 and shall acquaint the physicians about this potentially vision threatening, underdiagnosed, rare syndrome.

The impact of photoreceptor layer loss on different ocular tissues: Insights from FTIR spectroscopy.

Photoreceptor loss has significant consequences for visual function, and its management is a critical component for treating not only retinal diseases such as age-related macular degeneration and retinitis pigmentosa but also its ocular consequences. On the other hand, Fourier transform infrared spectroscopy is an excellent tool to investigate molecular structure and dynamics of biological samples, and as a non-destructive and label free measurement, it does not perturb the samples. In this study, detailed analyses of the recorded FTIR spectra from cornea, lens and sclera were performed to monitor the distribution of ocular abnormalities due to photoreceptor layer loss after 1, 3 and 6 days. FTIR data were statistically evaluated by multivariate analysis and Bonferroni means comparison. The obtained results revealed that ocular abnormalities associated with photoreceptor layer loss are varied among the investigated tissues, and comprise changes in both hydrogen bond network around proteins and lipid disorder. Structural modifications of protein secondary structure were reported in all investigated tissues. Clinically, the concluded information from FTIR data and its statistical evaluation can contribute to the development of therapeutic strategies for these heterogeneous changes.

Penetrating keratoplasty in brittle Cornea syndrome: Case series and review of the literature.

It concerns three siblings (two 28 year old twin boys and a 25 year old woman) who presented a previous history of rupture of eyeball in one eye and very poor vision in the other. At the first ophthalmoscopic and instrumental evaluation, three patients presented with bluish sclera and keratoglobus in the intact eye. A genetic analysis with whole exome sequencing was then performed on the three siblings, identifying a biallelic variant of the PRDM5 gene that led to the diagnosis of Brittle Cornea Syndrome (BCS), a rare autosomal recessive disorder characterized by corneal thinning and blue sclera. To preserve the only intact eye from possible breakage, the three siblings were trained in using protective measures (polycarbonate goggles etc.) to carry out close monitoring of symptoms and were asked to continue with follow-up visits for ocular and systemic diseases associated with BCS. Given the poor best corrected visual acuity achievable with glasses and contact lenses, penetrating keratoplasty was performed, achieving good visual acuity maintained in the 2-year follow-up in two of the three patients. Knowledge of this pathology and its clinical manifestations is essential for early diagnosis and correct management of this rare but very debilitating pathology. To our knowledge, this is the first case series of BCS reported in an Albanian population.

Two-dimensional elastic distribution imaging of the sclera using acoustic radiation force optical coherence elastography.

The scleral elasticity is closely related with many ocular diseases, but the relevant research is still insufficient. Here, we utilized optical coherence elastography to carefully study biomechanical properties of the sclera at different positions and under different intraocular pressures. Meanwhile, elastic wave velocity and Young's modulus of each position were obtained using a phase velocity algorithm. Accordingly, the two-dimensional elasticity distribution image was achieved by mapping the Young's modulus values to the corresponding structure based on the relationship between the position and its Young's modulus. Therefore, elastic information in regions-of-interest can be read and compared directly from the scleral structure, indicating that our method may be a very useful tool to evaluate the elasticity of sclera and provide intuitive and reliable proof for diagnosis and research.

Assessment of the ciliary muscle and scleral anterior thickness in high myopia by optical coherence tomography.

PURPOSE: To assess ciliary muscle (CM) and anterior scleral thickness (AST) dimensions in vivo in high myopia using swept-source optical coherence tomography (SS-OCT) and to compare with emmetropic and hyperopic subjects. METHODS: Cross-sectional study that included 34 high myopic patients (≥ -6 diopters [D]), 90 emmetropes (-1 to +1 D) and 38 hyperopic patients (≥ +3.5 D). CM thickness (CMT) and AST were measured in the temporal and nasal quadrants at 1, 2, and 3 mm from the scleral spur using SS-OCT. In addition, the length of the CM (CML) was evaluated. RESULTS: The dimensions of the CML and the CMT at any of their measurement points were greater in high myopes and emmetropes than in hyperopes, both in the nasal and temporal quadrants (P < .001). However, there were no differences between high myopes and emmetropes for any of the parameters (P ≥ .076) except for the CMT at 3 mm in the temporal quadrant (P < .001). There were no differences in the AST between high myopes, emmetropes and hyperopes, in any of the measurement points or quadrants studied (P > .05). CONCLUSIONS: The SS-OCT allows to measure the CM in vivo, not observing differences in its dimensions between high myopes and emmetropes, but they were smaller in hyperopes. In the measurement of the anterior sclera, no differences were observed between the three groups analyzed according to refraction.

A new look at an old problem: 3D modeling of accommodation reveals how age-related biomechanical changes contribute to dysfunction in presbyopia.

Presbyopia is an age-related ocular disorder where accommodative ability declines so that an individual's focusing range is insufficient to provide visual clarity for near and distance vision tasks without corrective measures. With age, the eye exhibits changes in biomechanical properties of many components involved in accommodation, including the lens, sclera, and ciliary muscle. Changes occur at different rates, affecting accommodative biomechanics differently, but individual contributions to presbyopia are unknown. We used a finite element model (FEM) of the accommodative mechanism to simulate age-related changes in lens stiffness, scleral stiffness, and ciliary contraction to predict differences in accommodative function. The FEM predicts how ciliary muscle action leads to lens displacement by initializing a tensioned unaccommodated lens (Phase 0) then simulating ciliary muscle contraction in accommodation (Phase 1). Model inputs were calibrated to replicate experimentally measured lens and ciliary muscle in 30-year-old eyes. Predictions of accommodative lens deformation were verified with additional imaging studies. Model variations were created with altered lens component stiffnesses, scleral stiffness, or ciliary muscle section activations, representing fifteen-year incremental age-related changes. Model variations predict significant changes in accommodative function with age-related biomechanical property changes. Lens changes only significantly altered lens thickening with advanced age (46% decrease at 75 years old) while sclera changes produced progressive dysfunction with increasing age (23%, 36%, 49% decrease at 45, 60, and 75 years old). Ciliary muscle changes effected lens position modulation. Model predictions identified potential mechanisms of presbyopia that likely work in combination to reduce accommodative function and could indicate effectiveness of treatment strategies and their dependency on patient age or relative ocular mechanical properties.

Fibrous finite element modeling of the optic nerve head region.

The optic nerve head (ONH) region at the posterior pole of the eye is supported by a fibrous structure of collagen fiber bundles. Discerning how the fibrous structure determines the region biomechanics is crucial to understand normal physiology, and the roles of biomechanics on vision loss. The fiber bundles within the ONH structure exhibit complex three-dimensional (3D) organization and continuity across the various tissue components. Computational models of the ONH, however, usually represent collagen fibers in a homogenized fashion without accounting for their continuity across tissues, fibers interacting with each other and other fiber-specific effects in a fibrous structure. We present a fibrous finite element (FFE) model of the ONH that incorporates discrete collagen fiber bundles and their histology-based 3D organization to study ONH biomechanics as a fibrous structure. The FFE model was constructed using polarized light microscopy data of porcine ONH cryosections, representing individual fiber bundles in the sclera, dura and pia maters with beam elements and canal tissues as continuum structures. The FFE model mimics the histological in-plane orientation and width distributions of collagen bundles as well as their continuity across different tissues. Modeling the fiber bundles as linear materials, the FFE model predicts the nonlinear ONH response observed in an inflation experiment from the literature. The model also captures important microstructural mechanisms including fiber interactions and long-range strain transmission among bundles that have not been considered before. The FFE model presented here advances our understanding of the role of fibrous collagen structure in the ONH biomechanics. STATEMENT OF SIGNIFICANCE: The microstructure and mechanics of the optic nerve head (ONH) are central to ocular physiology. Histologically, the ONH region exhibits a complex continuous fibrous structure of collagen bundles. Understanding the role of the fibrous collagen structure on ONH biomechanics requires high-fidelity computational models previously unavailable. We present a computational model of the ONH that incorporates histology-based fibrous collagen structure derived from polarized light microscopy images. The model predictions agree with experiments in the literature, and provide insight into important microstructural mechanisms of fibrous tissue biomechanics, such as long-range strain transmission along fiber bundles. Our model can be used to study the microstructural basis of biomechanical damage and the effects of collagen remodeling in glaucoma.

Nonsuperotemporal quadrant implantation of the Ahmed glaucoma valve using modified long scleral tunnel technique for intraocular pressure control

ABSTRACT Purpose: As superotemporal implantation of the Ahmed glaucoma valve is not always feasible in cases of refractory glaucoma, this study examined the characteristics and surgical outcomes of cases in which the valve was implanted in a nonsuperotemporal quadrant using a modified long scleral tunnel technique. Methods: This retrospective case-control study included 37 eyes with nonsuperotemporal quadrant--Ahmed glaucoma valve implantation in Group 1 and 69 eyes with superotemporal Ahmed glaucoma valve implantation in Group 2. The demographic characteristics of these groups, surgical outcomes, including complications, further surgical interventions, and surgical success rates were compared. Surgical success was defined as an intraocular pressure not exceeding 21 mmHg, accompanied by a minimum reduction of 20% in intraocular pressure from the baseline without any additional intraocular pressure-lowering procedures, and the absence of light perception loss or phthisis bulbi. Results: Group 1 had significantly higher numbers of eyes with secondary glaucoma and preoperative surgical procedures than Group 2 (p<0.05). Both groups had mean preoperative intraocular pressure values, and mean intraocular pressure values at the last visit of 34.2 and 27.9 months, 35.5 ± 1.5 and 35.8 ± 1.2 mmHg, and 14.5 ± 5 and 14.9 mmHg, respectively. Although both groups had 70.2% and 75.8% as their five-year cumulative probability of success, respectively, the rates of complications, revisional surgery, and additional surgical procedures did not differ significantly (p>0.05). Conclusion: The modified long scleral tunnel technique for Ahmed glaucoma valve implantation in nonsuperotemporal quadrants achieves intraocular pressure control and complication rates comparable to superotemporal implantation.