Dietary Alcohol Consumption Elicits Corneal Toxicity Through the Generation of Cellular Oxidative Stress.

Purpose: Clinical data suggest that alcohol use is associated with the development of signs and symptoms of dry eye disease. However, preclinical data investigating ocular toxicity after dietary alcohol consumption are lacking. In this study, we investigated the effects of alcohol on the ocular surface, in human corneal epithelial cells (HCE-T) in vitro and in C57BL/6JRj mice in vivo. Methods: HCE-T were exposed to clinically relevant doses of ethanol. To determine the effects of dietary alcohol consumption in vivo, wild-type mice were administered the Lieber-DeCarli liquid diet (5% vol/vol ethanol or isocaloric control) for 10 days ad libitum. Corneal fluorescein staining was performed to assess ocular surface damage. Histopathological and gene expression studies were performed on cornea and lacrimal gland tissue. Results: Sublethal doses of ethanol (0.01%-0.5%) resulted in a dose-dependent increase of cellular oxidative stress in corneal epithelial cells and a significant increase in NFE2L2 and downstream antioxidant gene expression, as well as an increase in NFκB signaling; short-term exposure (0.5%, 4 h) triggered significant corneal epithelial cell barrier breakdown. Exposure to the alcohol-containing diet caused a 3-fold increase in corneal fluorescein staining, with no effect on tear volumes. Corneal thickness was significantly reduced in the alcohol diet group, and corneal tissue revealed dysregulated antioxidant and NFκB signaling. Our data provide the first published evidence that alcohol exposure causes ocular toxicity in mice. Conclusions: Our results are consistent with clinical studies linking past alcohol consumption to signs of ocular surface disease.

Neuroprotective Effects of Citicoline on Methanol-Intoxicated Retina Model in Rats.

Purpose: This study aims to evaluate the effect of citicoline administration in suppressing retinal damage due to methanol intoxication. This study hypothesizes that citicoline will minimize the loss of retinal ganglion cells (RGCs), minimize disruption of photoreceptors, suppress ganglion layer edema, increase expression of bcl-2 as the antiapoptotic protein, and decrease expression of caspase-3 as the proapoptotic protein. Methods: Fifteen Sprague-Dawley rats were divided into 5 groups, including the control group (A); methanol groups, observed on day 3 (B1) and day 7 (B2); and methanol+citicoline groups, observed on day 3 (C1) and day 7 (C2). Rats in groups B and C were placed in an inhalation chamber filled with N2O:O2 during the experiment, then methanol was administered orally. Citicoline, 1 g/kg every 24 h, was orally administered for group C. Enucleation was performed and retinas of rats were prepared for histology and immunohistochemistry examination to evaluate photoreceptor morphology and RGC density, as well as bcl-2 and caspase-3 expression. Results: RGC density of citicoline-treated intoxicated rats was higher than no-citicoline methanol-intoxicated rats on both day 3 (P < 0.001) and day 7 (P < 0.001). The ganglion layer thickness of citicoline-treated intoxicated rats was thinner than no-citicoline intoxicated rats, which means citicoline-treated rats had milder ganglion layer edema. Citicoline-treated rats showed higher bcl-2 and lower caspase-3 expression than no-citicoline rats. No differences were found in photoreceptor findings among groups. Conclusions: This study demonstrated citicoline's potential benefits for management of ocular methanol intoxication. However, more preclinical and clinical trials are needed to obtain a preferred dosage and timing of citicoline administration.

Longitudinal evaluation of visual function and structure for detection of subclinical Ethambutol-induced optic neuropathy.

PURPOSE: To longitudinally evaluate the visual function and structure of patients taking ethambutol by various modalities and identify useful tests for detection of subclinical ethambutol-induced optic toxicity. METHODS: This retrospective study enrolled 84 patients with newly diagnosed tuberculosis treated with ethambutol. Best-corrected visual acuity (BCVA), color vision, contrast sensitivity, fundus and retinal nerve fiber layer (RNFL) photography, automated visual field (VF) test, and optical coherence tomography (OCT) were performed: prior to starting; every month during administration, and 1 month after stoppage. We longitudinally compared visual function and structure with the baseline and identified the occurrence of subclinical toxicity. RESULTS: BCVA, color vision, and contrast sensitivity showed no change from the baseline. Mean temporal RNFL thickness was significantly increased at 6 months (p = 0.014). Subclinical toxicity was found in 22 eyes of 14 patients (i.e., 13% of 168 eyes), in the forms of VFI decrease (VF index, 9 eyes of 6 patients), quadrant RNFL thickness increase (5 eyes of 4 patients), and VF pattern defect (12 eyes of 6 patients). 73% of the patients showed recovery to the baseline at 1 month post-stoppage. The risk factors for occurrence of subclinical toxicity were age, cumulative dose, and medication duration. CONCLUSION: Mean temporal RNFL thickness increased after administration. The VFI, quadrant RNFL thickness, and VF pattern defect could prove useful in assessment of subclinical toxicity. Medication duration was shown to be a strong risk factor for occurrence of subclinical toxicity.