Abstract
PURPOSE: The purpose of this study was to investigate whether the topographic location of retinal non-perfusion influences visual function, specifically low luminance visual acuity (LLVA) and best-corrected visual acuity (BCVA), in individuals with diabetes. METHODS: In this cross-sectional observational study, individuals with diabetes across the spectrum of diabetic retinopathy (DR) severity were enrolled. LLVA and BCVA were measured according to the Early Treatment Diabetic Retinopathy Study (ETDRS) protocol, with a 2.0-log unit neutral density filter for LLVA. Retinal ischemia was evaluated using ultra-widefield fluorescein angiography (UWF-FA) to manually quantify non-perfusion within (posterior ischemia) and outside (peripheral ischemia) the ETDRS seven fields. Macular ischemia was assessed by optical coherence tomography angiography (OCTA) using geometric perfusion deficits (GPDs) in both the superficial and deep capillary plexus (DCP). Associations between visual acuity and various explanatory variables, focusing on retinal ischemic parameters were assessed with linear mixed models. RESULTS: A total of 181 eyes from 126 patients without diabetic macular edema were analyzed. Increasing DR severity reduced both BCVA and LLVA. After adjusting other explanatory variables, age and posterior ischemia (estimate = -0.46, P = 0.046) were significant for LLVA. In contrast, age, sex, posterior ischemia (estimate = -0.50, P = 0.009), and GPD-DCP (estimate = -0.25, P = 0.049) were statistically significant for BCVA. CONCLUSIONS: Retinal ischemia's topographic location differentially affects visual function in diabetes. Posterior ischemia predominantly impacts LLVA, whereas both macular and posterior ischemia contribute to BCVA decline. These results highlight the importance of assessing retinal ischemia beyond the macula to better understand visual function deficits in patients with diabetes.