Allergic fungal sinusitis masquerading as cavernous sinus thrombosis.

Allergic fungal sinusitis (AFS), a noninvasive form of fungal sinusitis, is rarely seen in immunocompetent patients. Involvement of sphenoid sinus can result in proptosis and loss of vision. We report AFS masquerading as posterior cavernous sinus syndrome. A 59-year-old African-American man presented with right complete ptosis with ophthalmoplegia. After an initial work-up and imaging studies, patient underwent endonasal sphenoid surgery, which revealed characteristic 'allergic fungal mucin'. Cavernous sinus syndrome is a rare presenting clinical feature of allergic fungal sinusitis. Ophthalmologists should be aware of this rare presentation of relatively common otorhinological disease for timely referral and appropriate management.

Normative data for macular volume with high-definition spectral-domain optical coherence tomography (Spectralis).

PURPOSE: To establish normative data for macular volume by spectral-domain optical coherence tomography (SD-OCT) in subjects with no known retinal disease. METHODS: In an academic institutional setting, 50 subjects (age range 20-84 years) with no known retinal disease, best-corrected visual acuity 20/20, and normal intraocular pressure were enrolled. The subjects were divided into 3 age groups: group 1 included subjects 20-40 years of age, group 2 included subjects 41-60 years of age, and group 3 included subjects 61 years of age and older. All subjects underwent a complete ophthalmologic examination and testing, if needed, to rule out any retinal diseases or glaucoma. Retinal volume (RV) in 9 Early Treatment Diabetic Retinopathy Study (ETDRS) subfields and total macular volume (TMV) inclusive of all 9 subfields were analyzed. Statistical analyses were carried out using analysis of variance. RESULTS: Overall, the mean TMV ± SD for ETDRS circles with a diameter of 1, 2.22, and 3.45 mm was determined to be 3.04 ± 0.14 mm3. Among the ETDRS subfields, RV was highest in the nasal outer field, with a mean of 0.47 ± 0.02 mm3. The TMV did not show a significant difference with age (p = 0.17). However, TMV was significantly higher in males (p = 0.003) and in Caucasian and Asian subjects compared to African Americans (p = 0.017). CONCLUSIONS: Normative values for total macular volume in ETDRS subfields in otherwise healthy eyes were measured to be 3.04 ± 0.14 mm3.

Concurrent removal of intravitreal lens fragments after phacoemulsification with pars plana vitrectomy prevents development of retinal detachment.

AIM: To evaluate the outcomes of "concurrent vitrectomy" to retrieve dislocated lens fragment during phacoemulsification. METHODS: In a retrospective, observational case series, data of patients who underwent "concurrent" pars plana vitrectomy (PPV) for dislocated lens fragments between the period 2000 and 2008 were reviewed. Data collected included patient demographics, pre-operative visual acuity, intra-operative occurrence of retinal breaks, duration of follow up, post-operative intraocular pressure, final best-corrected visual acuity (BCVA), presence of cystoid macular edema (CME) and occurrence of rhegmatogenous retinal detachment (RRD). RESULTS: A total of 58 eyes of 58 patients were included in the study. At 12mo the mean postoperative BCVA was logMAR 0.17 (20/30) with a range of logMAR 0 to 0.69 (20/20 to 20/100), with 96.6% (56/58) of patients showing post-operative improvement in visual acuity (P=0.005). None of the patients developed postoperative retinal detachment, endophthalmitis or non-resolving uveitis at 12mo. CONCLUSION: Our study results suggest concurrent PPV for retained lens fragments after cataract surgery is beneficial and may decrease the risk of glaucoma and prevent development of RRD.

Human ciliary epithelium as a source of synthesis and secretion of vascular endothelial growth factor in neovascular glaucoma.

IMPORTANCE: Retinal ischemia-induced upregulation of vascular endothelial growth factor (VEGF) leads to endothelial proliferation of the anterior segment, resulting in neovascular glaucoma. OBJECTIVE: To investigate the ciliary epithelium as a possible source of VEGF in human eyes enucleated for intractable neovascular glaucoma. DESIGN, SETTING, AND PARTICIPANTS: In this proof-of-concept, laboratory-based study, 16 human enucleated eyes (8 with neovascular glaucoma and 8 as controls) were investigated. MAIN OUTCOMES AND MEASURES: Presence of VEGF by immunohistochemical analysis (VEGF protein) and in situ hybridization (VEGF messenger RNA). RESULTS: In eyes with neovascular glaucoma, strong VEGF immunoreaction in the nonpigmented epithelial cells of the ciliary processes and in the retina was noted. In situ hybridization for VEGF messenger RNA revealed a similar pattern, with positive stain results only in eyes with neovascular glaucoma. A minimal amount of VEGF immunostaining was seen in control eyes. CONCLUSIONS AND RELEVANCE: The nonpigmented ciliary epithelium is an important site of VEGF synthesis in patients with neovascular glaucoma. The ciliary epithelium may represent an additional focus of treatment in the management of neovascular glaucoma, especially in eyes that are nonresponsive to panretinal photocoagulation.

Aqueous interleukin-6 levels are superior to vascular endothelial growth factor in predicting therapeutic response to bevacizumab in age-related macular degeneration.

Objective. To prospectively evaluate the effect of intravitreal bevacizumab on aqueous levels of interleukin-6 (IL-6) and vascular endothelial growth factor (VEGF) in patients with exudative age-related macular degeneration (AMD) and correlate clinical outcomes with cytokine levels. Methods. 30 eyes of 30 patients with exudative AMD underwent intravitreal injection of bevacizumab three times at monthly intervals. The aqueous samples prior to the 1st injection (baseline) and 3rd injection were analyzed for VEGF and IL-6 levels. Subjects were subgrouped based upon change in the central subfield (CSF) macular thickness on SD-OCT at 8 weeks. Group 1 included patients (n = 14) with a decrease in CSF thickness greater than 10% from the baseline (improved group). Group 2 included patients (n = 16) who had a decrease in CSF thickness 10% or less (treatment-resistant). Results. In subgroup analysis, in both groups 1 and 2 patients, compared to aqueous VEGF, aqueous IL-6 levels showed a better correlation with CSF thickness on SD-OCT (r = 0.72 and 0.71, resp.). Conclusions. Aqueous IL-6 may be an important marker of treatment response or resistance in wet macular degeneration. Future therapeutic strategies may include targeted treatment against both VEGF and IL-6, in patients who do not respond to anti-VEGF treatment alone.

Lutein protects retinal pigment epithelium from cytotoxic oxidative stress.

CONTEXT: Lutein (LUT) and zeaxanthin (ZEA) are currently under investigation in clinical trials as prophylactic nutritional agents for age-related macular degeneration (AMD). However, dose used in these trials is empirical and not been investigated in in vitro studies. OBJECTIVE: In this study, we investigated the dose-response effect of LUT and ZEA in protecting retinal pigment epithelium (RPE) from oxidative stress, a common underlying pathology in AMD. METHODS: Three thousand cultured human retinal pigment epithelial cells (ARPE-19) were plated in 72-well plate and after 24 h were exposed to increasing concentrations of hydrogen peroxide (H2O2). ARPE-19 cells were exposed to four different concentrations of LUT (0.5, 1, 2 and 4 µg/mL) and ZEA (0.1, 0.2, 0.4 and 0.8 µg/mL). After 24 h incubation, cells were subjected to oxidative stress induced with H2O2. Cultures containing saline solution and dichloromethane served as controls. Cell viability was assessed using the WST-1 assay. Pathophysiological pathways were evaluated by measuring caspase-3 levels as an indicator of apoptosis induction. Reactive oxygen species (ROS) levels were measured using dihydrorhodamine-123. RESULTS: Cell viability as a percentage of control was 81.3%, 81.1%, and 88.8% at 0.5, 1, and 2 µg/ml, respectively of LUT (p < 0.001). The maximum cytoprotective effect was seen with LUT at 2 µg/mL. ZEA did not show any cytoprotective effect at all concentrations used in the study. Caspase-3 showed a corresponding decrease in levels with LUT (1 and 2 µg/ml). Significant decrease in ROS levels were measured only with LUT at 4 µg/ml (p = 0.02). DISCUSSION AND CONCLUSIONS: Results from our study provide in vitro data to support the epidemiologic studies, which are currently underway to provide evidence that lutein may act as cofactor that modulates processes implicated in AMD pathogenesis.

Resveratrol inhibits proliferation of hypoxic choroidal vascular endothelial cells.

PURPOSE: Resveratrol, a polyphenolic phytoalexin present in red wine, has a protective role against tumor-induced angiogenesis. Exudative age-related macular degeneration is characterized by hypoxia-induced choroidal vascular endothelial cell (CVEC) proliferation. In this study, we evaluated the effect of resveratrol on hypoxic CVECs and the underlying signaling pathways involved. METHODS: CVECs (RF/6A) after induction of hypoxia with cobalt chloride (CoCl2, 200 µM) were exposed to increasing doses of resveratrol (2, 4, 6, 8, 10, and 12 µg/ml). Cell viability was measured with 4-[3-(4Iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1, 3-benzene disulfonate (WST-1) colorimetric assay. The effect of resveratrol on hypoxia-induced vascular endothelial growth factor (VEGF) release was analyzed with enzyme-linked immunosorbent assay. The mechanistic pathway was further evaluated by analyzing phosphorylated stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) using immunoblot and cleaved caspase-3 with In-Cell enzyme-linked immunosorbent assay. RESULTS: Resveratrol inhibited hypoxic CVEC proliferation. Hypoxia-induced VEGF release (30.9±2.6 pg/ml) was inhibited in a dose-dependent fashion by 2, 4, 6, 8, 10, and 12 µg/ml resveratrol to 12.4±2.1, 11.0±1.9, 10.3±3.0, 7.5±1.9, 5.5±2.0, and 5.5±2.3 pg/ml, respectively. SAPK/JNK increased by 1.8-fold and 3.9-fold after treatment with 4 and 12 µg/ml resveratrol, respectively. Significant increase in caspase-3 levels was observed with 12 µg/ml resveratrol. CONCLUSIONS: Our study demonstrates that resveratrol suppresses hypoxic CVEC proliferation through activation of the SAPK/JNK pathway. Resveratrol, a nutritional supplement and inhibitor of CVECs, may be a useful adjunct to current anti-VEGF therapy in wet age-related macular degeneration.

Acute, bilateral, concurrent central retinal artery occlusion in sickle cell disease after use of tadalafil (Cialis).

IMPORTANCE: Sickle cell disease (SCD) is characterized by vaso-occlusive crisis. In the eye, central retinal artery occlusion (CRAO) is a rare complication in SCD, with only 1 previous report of bilateral, concurrent CRAO. We report a case of bilateral, concurrent CRAO in a patient with SCD, possibly precipitated by the use of phosphodiesterase 5 inhibitors. OBSERVATIONS: A 37-year-old African American woman with a known medical history significant for SCD and pulmonary arterial hypertension who was receiving treatment with tadalafil, a phosphodiesterase 5 inhibitor, developed bilateral, concurrent CRAO that persisted after exchange transfusion. CONCLUSIONS AND RELEVANCE: Bilateral CRAO secondary to SCD is extremely rare, with only 1 previous case report in the literature. The use of phosphodiesterase 5 inhibitors is an additional risk factor and may have contributed to the development of concurrent CRAO in this patient.

Differential sensitivity of choroidal endothelial, retinal ganglion, and retinal pigment epithelial cells in vitro to proton radiation.

PURPOSE: To evaluate the differential sensitivity of choroidal endothelial, retinal pigment epithelial, and retinal ganglion cells to escalating doses of proton beam radiation and to establish a safe dose range for the management of choroidal neovascularization associated with age-related macular degeneration (AMD). DESIGN: Laboratory investigation. METHODS: Proliferating simian choroidal endothelial cells (RF/6A), differentiated rat retinal ganglion cells (RGC-5), and serum-starved human retinal pigment epithelial cells (ARPE-19) were exposed to 2, 4, 8, and 12 cobalt gray equivalent of proton beam radiation and cell viability was quantified on day 9. Reactive oxygen species levels were analyzed. RESULTS: Significant decline of choroidal endothelial cell viability was noted as dose escalated from 4 to 8 cobalt gray equivalent with maximum effect observed at 12 cobalt gray equivalent. RGC-5 and ARPE-19 cell count decreased to 95% and 62.7% at 8 cobalt gray equivalent, respectively. Sub-analysis between 4 and 8 cobalt gray equivalent radiation revealed significant decrease in choroidal endothelial cell viability (43.1% at 7 cobalt gray equivalent and 32.3% at 8 cobalt gray equivalent of radiation). Correspondingly, RGC-5 and ARPE-19 cells did not show decrease in cell count or viability. Reactive oxygen species levels significantly increased in radiation-treated choroidal endothelial cells (8.3%-11.9%). CONCLUSIONS: At 6-8 cobalt gray equivalent proton beam radiation, retinal ganglion and retinal pigment epithelial cells are preserved while choroidal endothelial cells are completely inhibited. This dosage offers optimum therapeutic safety window for treatment using proton beam radiation for exudative AMD.

Prophylactic circumferential intraoperative laser retinopexy decreases the risk of retinal detachment after macular hole surgery.

PURPOSE: Pars plana vitrectomy with peeling of the internal limiting membrane is a well-established technique for the treatment of idiopathic macular holes with high success rates. Complications such as retinal tears may result from vitreous incarceration at the sclerotomy sites. Prophylactic laser retinopexy (LR) has recently been shown to decrease incidence of postvitrectomy rhegmatogenous retinal detachment but its efficacy in macular hole repair has not been established. In this study we evaluated the safety and efficacy of prophylactic LR and compared the patients to a control group that did not receive prophylactic treatment. METHODS: A retrospective, consecutive chart review was conducted comparing patients who underwent macular hole repair with LR to without LR. Patient demographics were collected and the number and time interval of retinal detachment in the 2 groups were compared. Statistical analysis was conducted between the 2 groups. RESULTS: A total of 144 eyes underwent macular hole repair during the study period. A total of 76 eyes underwent LR and 68 eyes did not undergo LR. There were no significant differences in baseline characteristics between the 2 groups. At 1 year, RD occurred in 1 eye (1.31%) in the LR group and in 8 eyes (8.82%) without LR group (p<0.01). CONCLUSIONS: Prophylactic LR decreases the incidence of postoperative retinal detachment a potentially disabling complication of macular hole repair surgery.

Evaluation of a Novel, Non Contact, Automated Focal Laser with Integrated (NAVILAS) Fluorescein Angiography for Diabetic Macular Edema.

PURPOSE: To evaluate the procedural experience and complications of a novel integrated laser delivery system (NAVILAS(®); OD-OS Teltow, Germany) that combines automated laser delivery with color fundus photography, fluorescein angiography (FA), fundus autofluorescence (FAF) and infrared imaging with a frequency doubled YAG laser. MATERIALS AND METHODS: This prospective study evaluated surgical experience with the NAVILAS automated photocoagulation system for the treatment of patients with diabetic macular edema (DME). Subjective assessment of the accuracy of laser spot placement and postoperative complications were documented. RESULTS: Twelve patients (7 males, 5 females) were enrolled in this pilot study. Five patients were phakic and 7 were pseudophakic. Image overlays and the tracking system allowed accurate delivery of laser spots of varying size, duration and power. None of the patients reported any pain and tolerated the procedure well. No complications were reported in the study. CONCLUSION: In this pilot study, the NAVILAS system allowed accurate laser spot placement with no complications in patients with DME. However a larger sample with longer follow up is required to determine the safety of this procedure.

Evaluation of proton beam radiation sensitivity of proliferating choroidal endothelial and retinal ganglion cells with clonogenic assay.

CONTEXT: Proton beam therapy offers the advantage of precise delivery with limited damage to the healthy tissue and is being tested in the management of exudative age-related macular degeneration (AMD). However, the dosages tested are empirical and not based on preclinical studies. OBJECTIVE: In this study we evaluated the effects of varying doses of proton beam radiation on choroidal endothelial cells (CECs) and retinal ganglion cells (RGCs) using clonogenic assay to determine differential sensitivity. MATERIALS AND METHODS: Each cell type has different efficiency to replicate (plating efficiency (PE)). PE of CEC (RF/6A) and RGC (RGC-5) grown in culture flasks was determined by plating 250 cells each (without any treatment) and counting the number of colonies after 13 days. Radiation induced sensitivity was determined by exposing the semi-confluent RF/6A and RGC-5 cells to proton beam at the doses of 0 (control), 2, 4, 8 and 12 cobalt gray equivalent (CGE). The ability of the cells to repair and replicate to form colonies were analyzed 13 days after radiation with crystal violet stain and the survival ratio was calculated. The significance of survival was analyzed using ANOVA (Graphpad Instat.3). RESULTS: The PE of CEC and RGC was 12.96 ± 0.29% and 40.7 ± 1.48%, respectively. A survival ratio of CEC at 2, 4, 8 and 12 CGE proton radiation was 66.0 ± 8.6%, 44.3 ± 6.5%, 7.6 ± 0.3% and 1.14 ± 0.06% on exposure to 2, 4, 8 and 12 CGE proton radiation, respectively, p < 0.01). Survival ratio of RGC was 71.1 ± 22.4% (p = 0.05), 40.2 ± 7.9%, 8.89 ± 2.6% and 0.78 ± 0.31% at 2, 4, 8 and 12 CGE dosages (p < 0.001). DISCUSSION: CEC showed dose-dependent decrease in survival rate with values attaining significance at all radiation dosages. In contrast, RGC was comparatively radio resistant and were able to replicate at lower doses and sensitive at higher doses after proton beam radiation. CONCLUSION: Since CECs proliferate during neovascularization, this clonogenic assay is a useful assay to assess the sensitivity of CEC to radiation. This study identified that CEC were more sensitive to proton beam radiation than RGC at all doses. This may provide a therapeutic window for administration of proton beam radiation in the management of AMD.

Infrared imaging and spectral-domain optical coherence tomography findings correlate with microperimetry in acute macular neuroretinopathy: a case report.

INTRODUCTION: Spectral-domain optical coherence tomography findings in a patient with acute macular neuroretinopathy, and correlation with functional defects on microperimetry, are presented. CASE PRESENTATION: A 25-year old Caucasian woman presented with bitemporal field defects following an upper respiratory tract infection. Her visual acuity was 20/20 in both eyes and a dilated fundus examination revealed bilateral hyperpigmentary changes in the papillomacular bundle. Our patient underwent further evaluation with spectral-domain optical coherence tomography, infrared and fundus autofluorescence imaging. Functional changes were assessed by microperimetry. Infrared imaging showed the classic wedge-shaped defects and spectral-domain optical coherence tomography exhibited changes at the inner segment-outer segment junction, with a thickened outer plexiform layer overlying these areas. Fluorescein and indocyanine green angiography did not demonstrate any perfusion defects or any other abnormality. Microperimetry demonstrated focal elevation in threshold correlating with the wedge-shaped defects in both eyes. CONCLUSION: Spectral-domain optical coherence tomography findings provide new evidence of the involvement of the outer plexiform layer of the retina in acute macular neuroretinopathy.

Evaluation of modified retinopathy of prematurity screening guidelines using birth weight as the sole inclusion criterion.

PURPOSE: The purpose was to determine if birth weight (BW) alone can be the sole criterion for screening infants at risk for retinopathy of prematurity (ROP). MATERIALS AND METHODS: In this retrospective, observational case series, 208 infants were screened for ROP using the American Association for Pediatric Ophthalmology and Strabismus (AAPOS) Guidelines (1997). Variables examined included gestational age (GA), birth weight (BW), and a composite variable BWGA Index [(grams × weeks)/1000], which takes into consideration both the birth weight and gestational age of the infant. Infants were divided into two groups: Group 1, BW ≤1250 g, and Group 2, BW >1250 g. Multivariate analysis was performed to detect factors predictive of ROP. Receiver operator characteristic (ROC) curves were generated to determine the efficacy of screening using the BW, GA, and BWGA Index. Statistical analyses were performed with logistic regression with a P-value of 0.05 or less indicating statistical significance. RESULTS: Varying stages of ROP were present in 116 of 416 eyes. Of the 105 eyes in Group 2, only 1 eye developed stage 1 ROP. Only Group 1 eyes developed stage 3 or higher ROP. The ROC curve for BW alone gave an area under the curve (AUC) of 0.797 (standard error [SE] = 0.0329, P < 0.0001); for GA, AUC was 0.801 (SE = 0.0340, P < 0.0001) and for the BWGA Index, the AUC was 0.808 (SE = 0.0324, P < 0.0001). Using 1250-g BW as a criterion for ROP screening would have decreased the number of screenings by 24%, and did not exclude any ROP higher than stage 1. CONCLUSION: Data from our neonatal intensive care unit suggest that birth weight ≤ 1250 g alone is an adequate parameter to identify premature infants at risk for ROP.

Comparative in vitro safety analysis of dyes for chromovitrectomy: indocyanine green, brilliant blue green, bromophenol blue, and infracyanine green.

PURPOSE: Vital dyes such as infracyanine green (IfCG), brilliant blue green (BBG), and bromophenol blue (BPB) have been used as an alternative to indocyanine green (ICG) during chromovitrectomy. We compared the in vitro toxicity of IfCG, BBG, and BPB with ICG on the retinal pigment epithelial cells and retinal ganglion cells at various concentrations to optimize the safe dose and duration of exposure. METHODS: Cultured retinal ganglion cells (RGC-5) and human retinal pigment epithelial cells (ARPE-19) were exposed to 2 concentrations (0.25 and 0.5 mg/mL) of ICG, IfCG, BBG, and BPB at various time intervals (1, 5, 15, and 30 minutes). Cell viability was quantified with neutral red assay, and mode of cell death was evaluated with flow cytometry-based Annexin V and propidium iodide staining. RESULTS: Exposure to ICG resulted in 48%-74% reduction in neutral red uptake in both RGC-5 and ARPE-19 cells, after an exposure time of ≥5 minutes compared with control (P < 0.001). Infracyanine green, BBG, and BPB were significantly less toxic on the 2 cell lines at exposure times <15 minutes. (Reduction in cell viability ranged from 6.9% ± 3.3% to 29.3% ± 7.4% when compared with control, P > 0.5.) However, among the newer dyes, BBG caused necrosis in retinal pigment epithelial cells and retinal ganglion cells as the exposure time period increased beyond 5 minutes. CONCLUSION: Newer vital dyes, IfCG, BBG, and BPB, are significantly less toxic on retinal ganglion cells and retinal pigment epithelial cells' cell lines when compared with ICG. Infracyanine green was least toxic among the three newer dyes studied.

Freezing adversely affects measurement of vascular endothelial growth factor levels in human aqueous samples.

PURPOSE: Aqueous levels of vascular endothelial growth factor (VEGF) can be a surrogate marker of intraocular VEGF activity and a measure of efficacy of anti-VEGF treatment in a variety of vasoproliferative retinal disorders, including diabetic retinopathy, age-related macular degeneration, and central retinal vein occlusion. Measurement of the VEGF level may be adversely affected by premeasurement variables, such as freezing and delay, in sample analysis. We aim to evaluate the effect of storage and delayed measurement of human aqueous VEGF levels in these conditions. METHODS: Aqueous samples collected from patients receiving intravitreal injection of bevacizumab for various retinal diseases were divided into two groups. In Group 1, the VEGF levels were analyzed on the same day; in Group 2, the VEGF levels were analyzed after 21 days of freezer storage (-80°C) using immunobead assay. Statistical comparison using a paired t-test was performed between the two groups. RESULTS: Thirty-one aqueous humor samples were collected, and the VEGF concentration for fresh samples was 7.8 ± 5.9 pg/mL (mean ± SD) compared to 6.5 ± 6.0 pg/mL in frozen samples, resulting in a statistically significant difference (P = 0.03). CONCLUSIONS: Accurate measurement of the VEGF level is a vital component of clinical decision-making. Delayed analysis of VEGF levels in aqueous samples may result in significant sample degradation and lower levels of measured VEGF.

Evaluation of choroidal endothelial cell proliferation after exposure to varying doses of proton beam radiation.

PURPOSE: Focal epiretinal radiation has emerged as a promising tool in the management of choroidal neovascularization associated with age-related macular degeneration. However, the dosages tested are not backed by cell culture studies used in the clinical setting empirically. METHODS: Choroidal endothelial cells (RF6A) were maintained in a log scale and exposed to a single fraction of 2, 4, 8, and 12 cobalt gray-equivalent of proton radiation with an internal control. Cell viability was quantified using Vi-cell XR and neutral red assay at days 5, 9, and 12 after radiation. Mitochondrial viability using WST-1 and reactive oxygen species levels using dihydrorhodamine 123 were measured at similar intervals. RESULTS: By using neutral red assay, on day 12, the percentages of viable cells compared with control were 100.1 ± 5.7%, 96.7 ± 23.3%, 27.6 ± 6.6%, and 19.5 ± 3% at radiation doses of 2, 4, 8, and 12 cobalt gray-equivalent, respectively (P < 0.001). Increase in reactive oxygen species levels correlated with the number of dead cells implicating reactive oxygen species as an intermediary molecule (r = 0.85-0.96). CONCLUSION: Our study shows sensitivity of cultured choroidal endothelial cells to proton beam radiation at doses of 8 and 12 cobalt gray-equivalent in an in vitro model.