Abstract
PURPOSE: The purpose of this study was to investigate aqueous humor total antioxidant capacity (TAC) and ascorbic acid (AA) levels of patients with diabetic retinopathy (DR), and their correlation with serum glycated hemoglobin (HbA1c) levels. METHODS: This case-control study enrolled 177 eyes from 177 patients that underwent cataract surgery between April 2019 and November 2022 in Chang Gung Memorial Hospital. Group 1 comprised 103 eyes from patients without diabetes; group 2 comprised 40 eyes from patients with diabetes but without DR; and group 3 comprised 34 eyes from patients with DR. Aqueous humor samples were collected and analyzed for TAC and AA levels using the ferric reducing/antioxidant AA assay. RESULTS: Aqueous humor TAC and AA levels were decreased in group 3 compared with group 2 and group 1 (P < 0.001 and P < 0.001). Aqueous humor TAC and AA levels were independent protective factors against DR in the diabetes population, with adjusted odds ratios of 0.109 (95% confidence interval [CI] = 0.017-0.719, P = 0.021) and 0.095 (95% CI = 0.012-0.726, P = 0.023), respectively. Aqueous humor TAC and AA concentrations were weakly negatively correlated with serum HbA1c levels, with Pearson's correlation coefficients of -0.339 (P = 0.013) and -0.341 (P = 0.012), respectively. CONCLUSIONS: TAC and AA had protective effects against DR. Decreased aqueous humor TAC and AA levels may serve as potential biomarkers for DR among the diabetes population. TRANSLATIONAL RELEVANCE: This study highlights the role of antioxidants in DR and provides foundation for future research on AA supplementation's potential for the prophylaxis and treatment of DR.