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Houston KE, Barrett AM. Patching for Diplopia Contraindicated in Patients with Brain Injury?. Optom Vis Sci 2017;94(1):120-124.Abstract

PURPOSE: Patching for double vision is a common palliative treatment for head-trauma patients with acquired strabismus when prisms are not feasible. METHODS: We review literature on spatial neglect and discuss possible effects of monocular occlusion on spatial attention. RESULTS: Patching the left eye has been shown to worsen spatial judgments in some brain-injured patients with left neglect by inhibiting the right superior colliculus further impairing contralateral leftward orienting (the Sprague Effect). CONCLUSIONS: Because more peripheral parts of the visual field increasingly project to the contralateral superior colliculus with the temporal crescent being entirely contralateral, avoiding patching of the temporal crescent was advised, and in most cases can be achieved by taping off the spectacle lens and avoiding an elastic eye patch.

Kobashi H, Kamiya K, Shimizu K. Dry Eye After Small Incision Lenticule Extraction and Femtosecond Laser-Assisted LASIK: Meta-Analysis. Cornea 2017;36(1):85-91.Abstract

PURPOSE: To compare postoperative ocular surface integrity and innervation between small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK). METHODS: The Cochrane Central Register of Controlled Trials, PubMED, and EMBASE were searched for prospective comparative studies. Trials meeting the selection criteria were quality appraised, and the data were extracted by 2 independent authors. The weighted mean differences (WMDs) and 95% confidence intervals (CIs) were used to compare dry eye examinations and corneal subbasal nerve density (SMILE-FS-LASIK). RESULTS: The study covered 5 trials. No significant difference was found in the Schirmer test score between both groups (WMD = -1.91 and 0.27; 95% CI, -5.02 to 1.20 and -0.99 to 1.54; P = 0.23 and 0.67 at 1- and 6-month follow-ups, respectively). Tear breakup time in the SMILE group significantly exceeded that in the FS-LASIK group (WMD = 0.65 and 1.14; 95% CI, 0.20-1.10 and 0.18-2.10; P = 0.004 and 0.02, at 1- and 6-month follow-ups, respectively). Ocular surface disease index scores were significantly better in the SMILE group 6 months postoperatively (WMD = -10.12, 95% CI, -16.07 to -4.18, P = 0.0008). No significant difference was found in tear osmolarity between both groups (WMD = -5.19 and -6.37; 95% CI, -17.15 to 6.76 and -22.74 to 10.00; P = 0.39 and 0.45 at 1- and 6-month follow-ups, respectively). Higher corneal sensitivity was observed in the SMILE group 1 and 6 months postoperatively (WMD = 11.35 and 3.49; 95% CI, 7.29-15.40 and 1.76-5.21; P < 0.00001 and <0.0001, at 1- and 6-month follow-ups, respectively). Corneal subbasal nerve density was also significantly higher in SMILE-treated eyes than it was in FS-LASIK-treated eyes 1 month postoperatively (WMD = 4.72, 95% CI, 1.10-8.34, P = 0.01). CONCLUSIONS: According to this meta-analysis, the SMILE procedure has fewer negative impacts on the ocular surface and corneal innervation than does FS-LASIK. Furthermore, SMILE shows superiority over FS-LASIK by a exhibiting a lower risk of postoperative dry eye.

Houston KE, Paschalis EI, Angueira DC, Bronstad MP, Barrett AM, Iaccarino MA. Restoration of Vision After Brain Injury Using Magnet Glasses. Am J Phys Med Rehabil 2017;96(4):e70-e74.Abstract

Visual impairments are common after traumatic brain injury (TBI) and negatively affect quality of life. We describe a 39-year-old woman with a severe TBI who was evaluated by the inpatient optometry and vision rehabilitation service with findings of complete right homonymous hemianopia and right cranial nerve III palsy with 30-degree right exotropia (eye turn out) and complete right ptosis (eyelid will not open). The 30-degree exotropia advantageously generated 30 degrees of right visual field expansion when the right ptosis was treated with a magnetic levator prosthesis, which restores eyelid opening. Once opened, the patient used visual field expansion derived from a right exotropia to overcome functional impairments caused by right hemianopia. Field expansion improved the patient's wheelchair mobility and reaching tasks during inpatient therapy. This is the first report of visual field expansion by strabismus facilitated by correction of ptosis. Strabismus should be considered for its potential field expansion benefits when homonymous visual deficits are present, before considering patching. A multidisciplinary vision rehabilitation team is well suited to make this determination.

Birnbaum FA, Hamrah P, Jacobs DS, Song BJ. Acquired Corneal Neuropathy and Photoallodynia Associated With Malposition of an Ex-PRESS Shunt. J Glaucoma 2017;26(1):e19-e21.Abstract

PURPOSE: Corneal neuropathy is a recently described disease process that is not well understood and is likely underdiagnosed as a result. This is the first reported case of an acquired corneal neuropathy associated with malposition of an Ex-PRESS shunt. METHODS: A single case report. RESULTS: We report the case of a 50-year-old man with a history of multiple procedures for glaucoma who subsequently developed photoallodynia and corneal neuropathy in association with malposition of an Ex-PRESS shunt in the peripheral cornea. Laser confocal microscopy (HRT3/RCM) of the cornea showed the presence of neuromas, decreased nerve density, and a significant increase of dendritiform immune cells consistent with our diagnosis. Initial treatment with steroid pulse therapy did not result in decreased inflammation or symptomatic improvement leading to surgical explantation of the shunt. One month after surgery, there was noticeable improvement in the patient's pain and photoallodynia (approximately 40%) as well as the abnormalities seen on confocal microscopy. CONCLUSIONS: We hypothesize that poor Ex-PRESS shunt positioning can act as a nidus for corneal inflammation, resulting in corneal neuropathy and lowering of the nociception threshold.

Jee D, Keum N, Kang S, Arroyo JG. Sleep and diabetic retinopathy. Acta Ophthalmol 2017;95(1):41-47.Abstract

PURPOSE: To investigate the association between sleep duration and diabetic retinopathy (DR). METHODS: A population-based cross-sectional study using a nation-wide, systemically stratified, multistage, clustered sampling method included a total of 1670 subjects aged ≥40 years with diabetes who participated in the Korean National Health and Nutrition Examination Survey during 2008-2012. All participants performed standardized interviews, including self-reported sleep duration, and comprehensive ophthalmic examinations. Seven standard retinal fundus photographs were obtained from both eyes after pupil dilatation. Diabetic retinopathy (DR) was graded and classified as any DR and vision-threatening DR. Participants were stratified into men and women. RESULTS: The mean sleep duration was 6.71 hr/day. In men, adjusted OR of any DR was 1.88 [95% confidence interval (OR), 1.01-3.59] in those with ≤5 hr sleep, and 2.19 (95% CI, 1.01-4.89) in those with ≥9 hr sleep, compared to in subjects with 6-8 hr sleep, after adjusting for potential confounders including age, body mass index (BMI), diabetes duration, fasting glucose level, haemoglobin A1c levels and hypertension. In women, however, no significant association between sleep duration and DR was found. The vision-threatening DR was not significantly associated with sleep duration in either men or women. CONCLUSIONS: Short and long sleep was associated with high prevalence of DR in men. Sleep deprivation may be involved in the pathogenesis of DR development.

Di Zazzo A, Tahvildari M, Subbarayal B, Yin J, Dohlman TH, Inomata T, Mashaghi A, Chauhan SK, Dana R. Proangiogenic Function of T Cells in Corneal Transplantation. Transplantation 2017;101(4):778-785.Abstract

BACKGROUND: Corneal neovascularization increases the risk of T cell-mediated allograft rejection. Here, we investigate whether T cells promote angiogenesis in transplantation. METHODS: Conventional effector T cells were collected from draining lymph nodes of allogeneic or syngeneic corneal transplanted BALB/c mice. T cells were either cocultured with vascular endothelial cells (VECs) to assess VEC proliferation or used in a mixed lymphocyte reaction assay. Messenger RNA (mRNA) expression of vascular endothelial growth factor (VEGF)-A, -C, and VEGF receptor 2 (VEGF-R2) in VECs was assessed by real-time PCR. VEGF-A protein expression was determined by enzyme-linked immunosorbent assay. Flow cytometry was used to analyze VEGF-R2 expression in corneal CD31 cells, and VEGF-A and IFNγ expression in corneal CD4 T cells. RESULTS: Allogeneic T cells from high-risk (HR) grafted mice induced more VEC proliferation than those from syngeneic transplant recipients (P = 0.03). Vascular endothelial growth factor-A mRNA and protein expression were higher in T cells from draining lymph nodes (P = 0.03 and P = 0.04, respectively) and cornea (protein; P = 0.04) of HR compared with low-risk (LR) grafted hosts. Vascular endothelial growth factor-A, VEGF-C, and VEGF-R2 mRNA expression were increased in VECs when cocultured with T cells from HR transplants compared with LR transplants and naive mice. In addition, IFNγ blockade in T cell/VEC coculture increased VEC proliferation and VEGF-A protein expression, whereas blocking VEGF-A significantly reduced VEC proliferation (P = 0.04). CONCLUSIONS: Allogeneic T cells from corneal transplant hosts promote VEC proliferation, probably via VEGF-A signaling, whereas IFNγ shows an antiangiogenic effect. Our data suggest that T cells are critical mediators of angiogenesis in transplantation.

Cai S, Elze T, Bex PJ, Wiggs JL, Pasquale LR, Shen LQ. Clinical Correlates of Computationally Derived Visual Field Defect Archetypes in Patients from a Glaucoma Clinic. Curr Eye Res 2017;42(4):568-574.Abstract

PURPOSE: To assess the clinical validity of visual field (VF) archetypal analysis, a previously developed machine learning method for decomposing any Humphrey VF (24-2) into a weighted sum of clinically recognizable VF loss patterns. MATERIALS AND METHODS: For each of 16 previously identified VF loss patterns ("archetypes," denoted AT1 through AT16), we screened 30,995 reliable VFs to select 10-20 representative patients whose VFs had the highest decomposition coefficients for each archetype. VF global indices and patient ocular and demographic features were extracted retrospectively. Based on resemblances between VF archetypes and clinically observed VF patterns, hypotheses were generated for associations between certain VF archetypes and clinical features, such as an association between AT6 (central island, representing severe VF loss) and large cup-to-disk ratio (CDR). Distributions of the selected clinical features were compared between representative eyes of certain archetypes and all other eyes using the two-tailed t-test or Fisher exact test. RESULTS: 243 eyes from 243 patients were included, representative of AT1 through AT16. CDR was more often ≥ 0.7 among eyes representative of AT6 (central island; p = 0.002), AT10 (inferior arcuate defect; p = 0.048), AT14 (superior paracentral defect; p = 0.016), and AT16 (inferior paracentral defect; p = 0.016) than other eyes. CDR was more often < 0.7 among eyes representative of AT1 (no focal defect; p < 0.001) and AT2 (superior defect; p = 0.027), which was also associated with ptosis (p < 0.001). AT12 (temporal hemianopia) was associated with history of stroke (p = 0.022). AT11 (concentric peripheral defect) trended toward association with trial lens correction > 6D (p = 0.069). CONCLUSIONS: Shared clinical features between computationally derived VF archetypes and clinically observed VF patterns support the clinical validity of VF archetypal analysis.

Pasovic L, Eidet JR, Olstad OK, Chen DF, Lyberg T, Utheim TP. Impact of Storage Temperature on the Expression of Cell Survival Genes in Cultured ARPE-19 Cells. Curr Eye Res 2017;42(1):134-144.Abstract

PURPOSE: The development of a suitable storage method for retinal pigment epithelium (RPE) is necessary in the establishment of future RPE replacement therapy, and storage temperature has proven to be pivotal for cell survival. ARPE-19, a widely used model for RPE, has been shown to yield the greatest number of viable cells when stored at 16°C compared to other storage temperatures. In this study, we analyze the gene expression profile of cultured ARPE-19 cells after seven days of storage at different temperatures in an effort to predict the gene-level consequences of storage of RPE transplants. MATERIALS AND METHODS: ARPE-19 cells were cultured until confluence and then stored in minimum essential medium at 4°C, 16°C, and 37°C for seven days. The total RNA was isolated and the gene expression profile was determined using DNA microarrays. The Results were validated using qPCR. RESULTS: Principal component and hierarchical clustering analyses show that the gene expression profiles of cell cultures stored at different temperatures cluster into separate groups. Cultures stored at 4°C cluster closest to the control cultures that were not stored and display the least change in gene expression after storage (157 differentially expressed genes). Cultures stored at 16°C and 37°C display a much larger change in differential gene expression (1787 and 1357 differentially expressed genes, respectively). At 16°C, the expression of several genes with proposed tumor suppressor functions was markedly increased. Changes in regulation of several known signaling pathways and of oxidative stress markers were discovered at both 16°C and 37°C, and activation of the angiogenesis marker vascular endothelial growth factor (VEGF) was discovered at 37°C. There was no evidence of the activation of inflammatory processes in stored cell cultures. CONCLUSION: ARPE-19 cultures stored at 16°C show the greatest propensity to modulate their gene expression profile in a manner that supports cell survival during storage.

Hodges RR, Li D, Shatos MA, Bair JA, Lippestad M, Serhan CN, Dartt DA. Lipoxin A4 activates ALX/FPR2 receptor to regulate conjunctival goblet cell secretion. Mucosal Immunol 2017;10(1):46-57.Abstract

Conjunctival goblet cells play a major role in maintaining the mucus layer of the tear film under physiological conditions as well as in inflammatory diseases like dry eye and allergic conjunctivitis. Resolution of inflammation is mediated by proresolution agonists such as lipoxin A4 (LXA4) that can also function under physiological conditions. The purpose of this study was to determine the actions of LXA4 on cultured rat conjunctival goblet cell mucin secretion, intracellular [Ca(2+)] ([Ca(2+)]i), and identify signaling pathways activated by LXA4. ALX/FPR2 (formyl peptide receptor2) was localized to goblet cells in rat conjunctiva and in cultured goblet cells. LXA4 significantly increased mucin secretion, [Ca(2+)]i, and extracellular regulated kinase 1/2 (ERK 1/2) activation. These functions were inhibited by ALX/FPR2 inhibitors. Stable analogs of LXA4 increased [Ca(2+)]i to the same extent as LXA4. Sequential addition of either LXA4 or resolvin D1 followed by the second compound decreased [Ca(2+)]i of the second compound compared with its initial response. LXA4 activated phospholipases C, D, and A2 and downstream molecules protein kinase C, ERK 1/2, and Ca(2+)/calmodulin-dependent kinase to increase mucin secretion and [Ca(2+)]i. We conclude that conjunctival goblet cells respond to LXA4 to maintain the homeostasis of the ocular surface and could be a novel treatment for dry eye diseases.

Aggarwal S, Yamaguchi T, Dana R, Hamrah P. Exophiala phaeomuriformis Fungal Keratitis: Case Report and In Vivo Confocal Microscopy Findings. Eye Contact Lens 2017;43(2):e4-e6.Abstract

PURPOSE: Corneal infections, particularly fungal keratitis due to rare fungal species, pose a diagnostic and therapeutic challenge because of difficulty in identification and varying susceptibility profiles. In this study, we report the first case of fungal keratitis because of Exophiala phaeomuriformis. METHODS: We report the clinical findings and microbial identification techniques of a case of fungal keratitis due to E. phaeomuriformis. An 84-year-old woman presented with redness, pain, and itching in the left eye for 2 weeks. Slit-lamp biomicroscopy revealed one broken suture from previous penetrating keratoplasty (PKP), black infiltrates at the 4-o'clock position, without an overlying epithelial defect and hypopyon. Microbial identification was based cultures on Sabouraud dextrose agar and DNA sequencing and correlations to laser in vivo confocal microscopy (IVCM; Heidelberg Retinal Tomograph 3/Rostock Cornea Module, Heidelberg Engineering) and multiphoton microscopy (Ultima Microscope; Prairie Technologies) images. RESULTS: Slit-lamp biomicroscopy revealed one broken suture from previous PKP, black infiltrates at the 4-o'clock position, without an overlying epithelial defect and hypopyon. Based on a clinical suspicion of fungal keratitis, antifungals and fortified antibiotics were started. However, the patient did not respond to therapy and required urgent PKP. After surgery, the patient was maintained on topical and systemic voriconazole and also topical 2% cyclosporine for 5 months because of possibility of scleral involvement noticed during surgery. At the end of the treatment period, her vision improved from hand motion to 20/40, with no recurrence observed in a follow-up period of 1 year. Results of diagnostic tests were supported by fungal elements in stroma on IVCM. Culture from the infiltrate grew black yeast. DNA sequencing led to the diagnosis of E. phaeomuriformis keratitis. Antifungal susceptibility testing revealed sensitivity to voriconazole. CONCLUSION: This is, to our knowledge, the first reported case of E. phaeomuriformis fungal keratitis. Diagnostic testing included slit-lamp biomicroscopy, which revealed pigmented infiltrates, culture plates grew black yeast, microscopy showed branched fungal hyphae with budding conidia, and physiological features showed tolerance to high temperatures, nitrate assimilation, and ribosomal DNA sequencing. Collectively, these tests demonstrate unique features seen for this microorganism. High suspicion should be kept with pigmented infiltrates and with dark yeast on culture plates. Prompt and aggressive medical management with voriconazole or therapeutic PKP in nonresponsive cases is essential to prevent irreversible loss of vision.

Jakobiec FA, Grob SR, Stagner AM, Curtin H, Massoud V, Fay A. Orbital Conjunctival Cyst Associated With the Superior Rectus-Levator Muscles: A Clinicopathologic Study. Ophthal Plast Reconstr Surg 2017;33(1):e1-e4.Abstract

A 55-year-old woman had a right orbital cyst detected incidentally on radiographic imaging. The patient's symptoms were mild and included intermittent pain and vertical diplopia; the patient was not aware of any visual decline. There was a palpable mass beneath the superior orbital rim. Radiographic imaging revealed a well-demarcated cystic lesion in the right superior orbit between the levator palpebrae superioris and superior rectus muscles. The mass was completely excised via a transconjunctival approach. Histopathologic evaluation disclosed a conjunctival cyst lined by nonkeratinized squamous epithelium with scattered, rare goblet cells. This case combined with 5 other similar reported cases suggests that an intermuscular cyst located in the superior rectus-levator complex is most likely of congenital embryonic conjunctival origin.

Fay A, Dolman PJ. Diseases and Disorders of the Orbit and Ocular Adnexa, 1st Edition. 1st ed. Elsevier; 2016.Abstract

Drawing from the knowledge and expertise of more than 70 contributing international experts, Diseases and Disorders of the Orbit and Ocular Adnexa thoroughly covers the state of the art in orbital and periocular disease from the perspective of a variety of specialties. Clearly written and profusely illustrated, it covers the clinical presentation, pathophysiology, natural history, and management alternatives of disease processes affecting the orbit, eyelids, lacrimal system, and upper face. With a singular focus on the diagnosis and management of orbital and ocular adnexal disease, this authoritative text gives you the information you need to excel both in practice and on exams in the specialty of ophthalmic plastic and reconstructive surgery.


Key Features

Offers an in-depth and thorough approach to the pathophysiology of oculoplastics and orbital disease, incorporating the perspectives of numerous specialties - all in one convenient volume.

  • Uses an easy-to-follow, templated format throughout so you can find what you need quickly.
  • Covers new information not included in other texts, such as antibody testing in dysthyroid conditions and a rapidly emerging array of targeted immunosuppressive medications for the treatment of inflammatory orbital disease.
  • Includes hot topics such as the classification and management of orbital inflammatory disease; vascular neoplasms and malformations; periocular dermatology; burn management; facial paralytic disease; and the pathogenesis, evaluation and management of lymphoproliferative disease.
  • Features more than 1,200 high-quality clinical, imaging, and histological illustrations that provide clear visual examples of orbital disease.
  • Written by an international team of experts from five continents (across multiple specialties including ophthalmology, dermatology, burn management, plastic surgery, otolaryngology, endocrinology, and pathology) led by Dr. Aaron Fay and Dr. Peter J. Dolman.
  • Expert Consult™ eBook version included with purchase. This enhanced eBook experience allows you to search all of the text, figures, and references from the book on a variety of devices.


Author Information
By Aaron Fay, MD, Assistant Professor, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA and Peter J Dolman, MD, FRCSC , Clinical Professor, Division Head of Oculoplastics and Orbit; Director of Fellowship Programmes, Department of Ophthalmology, University of British Columbia, Vancouver, BC, Canada

 

Lammer J, Prager SG, Cheney MC, Ahmed A, Radwan SH, Burns SA, Silva PS, Sun JK. Cone Photoreceptor Irregularity on Adaptive Optics Scanning Laser Ophthalmoscopy Correlates With Severity of Diabetic Retinopathy and Macular Edema. Invest Ophthalmol Vis Sci 2016;57(15):6624-6632.Abstract

Purpose: To determine whether cone density, spacing, or regularity in eyes with and without diabetes (DM) as assessed by high-resolution adaptive optics scanning laser ophthalmoscopy (AOSLO) correlates with presence of diabetes, diabetic retinopathy (DR) severity, or presence of diabetic macular edema (DME). Methods: Participants with type 1 or 2 DM and healthy controls underwent AOSLO imaging of four macular regions. Cone assessment was performed by independent graders for cone density, packing factor (PF), nearest neighbor distance (NND), and Voronoi tile area (VTA). Regularity indices (mean/SD) of NND (RI-NND) and VTA (RI-VTA) were calculated. Results: Fifty-three eyes (53 subjects) were assessed. Mean ± SD age was 44 ± 12 years; 81% had DM (duration: 22 ± 13 years; glycated hemoglobin [HbA1c]: 8.0 ± 1.7%; DM type 1: 72%). No significant relationship was found between DM, HbA1c, or DR severity and cone density or spacing parameters. However, decreased regularity of cone arrangement in the macular quadrants was correlated with presence of DM (RI-NND: P = 0.04; RI-VTA: P = 0.04), increasing DR severity (RI-NND: P = 0.04), and presence of DME (RI-VTA: P = 0.04). Eyes with DME were associated with decreased density (P = 0.04), PF (P = 0.03), and RI-VTA (0.04). Conclusions: Although absolute cone density and spacing don't appear to change substantially in DM, decreased regularity of the cone arrangement is consistently associated with the presence of DM, increasing DR severity, and DME. Future AOSLO evaluation of cone regularity is warranted to determine whether these changes are correlated with, or predict, anatomic or functional deficits in patients with DM.

Grotting LA, Davoudi S, Palenzuela D, Papaliodis GN, Sobrin L. Association of Low Vitamin D Levels With Noninfectious Anterior Uveitis. JAMA Ophthalmol 2016;Abstract

Importance: Vitamin D plays an important role in both the innate and adaptive immune systems. It has been shown to contribute to the etiology of T-cell-mediated autoimmune diseases through the upregulation of type 2 anti-inflammatory T helper cells and the suppression of type 1 T helper cells. Noninfectious uveitis is postulated to be caused by immune dysfunction. Objective: To determine whether there is an association between vitamin D levels and noninfectious anterior uveitis. Design, Setting, and Participants: This was a case-control study. We identified patients with and without noninfectious uveitis using the Massachusetts Eye and Ear Infirmary Ocular Inflammation Database and electronic medical records from March 1, 2008, to December 12, 2015, at the Massachusetts Eye and Ear Infirmary Uveitis and Comprehensive Ophthalmology Clinics. One hundred patients with noninfectious anterior uveitis and 100 patients without uveitis were recruited. Patients with noninfectious uveitis were diagnosed by fellowship-trained uveitis specialists after exclusion of infectious causes and neoplastic masquerades of uveitis. All patients included had a total 25-hydroxyvitamin D level recorded. Multivariate regression models were constructed to determine the association between vitamin D levels and the presence of uveitis. Main Outcome and Measure: Presence of noninfectious anterior uveitis. Results: We identified 100 patients (64 white, 8 African American, 25 Asian, and 3 Hispanic) with a mean (SD) age of 51.8 (15.9) years (26 men) and 100 control individuals (58 white, 23 African American, 8 Asian, and 11 Hispanic) with a mean (SD) age of 53.6 (16.2) years (27 men). Hypovitaminosis D was associated with noninfectious uveitis in the univariate analysis (odds ratio, 2.53; 95% CI, 1.42-4.51; P = .002). The association in multivariate regression after adjusting for age, sex, and race/ethnicity was 2.96 (95% CI, 1.60-5.50; P = .001) The odds of developing uveitis were 4% lower for every 1-ng/mL increase in vitamin D level (odds ratio, 0.96; 95% CI, 0.93-0.99; P = .01) in the main multivariate analysis. Conclusions and Relevance: In this retrospective study, lower vitamin D levels were associated with an increased risk of noninfectious anterior uveitis. However, this does not confirm a causal effect.

Zhao J, Zhu T-H, Chen W-C, Peng S-M, Huang X-S, Cho K-S, Chen DF, Liu G-S. Optic neuropathy and increased retinal glial fibrillary acidic protein due to microbead-induced ocular hypertension in the rabbit. Int J Ophthalmol 2016;9(12):1732-1739.Abstract

AIM: To characterize whether a glaucoma model with chronic elevation of the intraocular pressure (IOP) was able to be induced by anterior chamber injection of microbeads in rabbits. METHODS: In order to screen the optimal dose of microbead injection, IOP was measured every 3d for 4wk using handheld applanation tonometer after a single intracameral injection of 10 µL, 25 µL, 50 µL or 100 µL microbeads (5×10(6) beads/mL; n=6/group) in New Zealand White rabbits. To prolong IOP elevation, two intracameral injections of 50 µL microbeads or phosphate buffer saline (PBS) were made respectively at days 0 and 21 (n=24/group). The fellow eye was not treated. At 5wk after the second injection of microbeads or PBS, bright-field microscopy and transmission electron microscopy (TEM) were used to assess the changes in the retina. The expression of glial fibrillary acidic protein (GFAP) in the retina was evaluated by immunofluorescence, quantitative real-time polymerase chain reaction and Western blot at 5wk after the second injection of microbeads. RESULTS: Following a single intracameral injection of 10 µL, 25 µL, 50 µL or 100 µL microbead, IOP levels showed a gradual increase and a later decrease over a 4wk period after a single injection of microbead into the anterior chamber of rabbits. A peak IOP was observed at day 15 after injection. No significant difference in peak value of IOP was found between 10 µL and 25 µL groups (17.13±1.25 mm Hg vs 17.63±0.74 mm Hg; P=0.346). The peak value of IOP from 50 µL group (23.25±1.16 mm Hg) was significantly higher than 10 µL and 25 µL groups (all P<0.05). Administration of 100 µL microbead solution (23.00±0.93 mm Hg) did not lead to a significant increase in IOP compared to the 50 µL group (P=0.64). A prolonged elevated IOP duration up to 8wk was achieved by administering two injections of 50 µL microbeads (20.48±1.21 mm Hg vs 13.60±0.90 mm Hg in PBS-injected group; P<0.05). The bright-field and TEM were used to assess the changes of retinal ganglion cells (RGCs). Compared with PBS-injected group, the extended IOP elevation was associated with the degeneration of optic nerve, the reduction of RGC axons (47.16%, P<0.05) and the increased GFAP expression in the retina (4.74±1.10 vs 1.00±0.46, P<0.05). CONCLUSION: Two injections of microbeads into the ocular anterior chamber of rabbits lead to a prolonged IOP elevation which results in structural abnormality as well as loss in RGCs and their axons without observable ocular structural damage or inflammatory response. We have therefore established a novel and practical model of experimental glaucoma in rabbits.

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