Correlation between visual acuity and diabetic macular ischemia using optical coherence tomography angiography

Context: Diabetic macular ischemia affects visual function to a variable degree. Aims: This study aims to find whether parameters of ischemia measured on optical coherence tomography angiography (OCTA) correlate with best spectacle-corrected visual acuity (BCVA). Settings and Design: A cross-sectional study was done on 33 eyes with diabetic retinopathy (DR) and 11 nondiabetic control eyes. Subjects and Methods: A 3 mm × 3 mm OCTA images of the superficial capillary plexus (SCP), intermediate capillary plexus (ICP), deep capillary plexus (DCP), and full-thickness retinal slabs were obtained and used to measure foveal avascular zone (FAZ) area and circularity index (CI) manually. Statistical Analysis Used: Statistical comparison between the diabetic and control groups and correlation with BCVA was calculated. Results: CI was significantly higher in controls in each of the SCP (P > 0.001), ICP (P > 0.05), DCP (P = 0.005), and full retinal thickness (P < 0.05) slabs. Compared to the moderate nonproliferative DR group, the control group had a smaller FAZ (P = 0.04) and higher CI (P = 0.01) in the DCP slab. Neither the FAZ area nor the CI was significantly correlated with BCVA in any of the slabs. Conclusions: OCTA can detect a measurable degree of ischemia in diabetic eyes compared to controls. CI is the most sensitive parameter for this purpose. The DCP shows the earliest affection with increasing grades of DR. FAZ area and CI are not good indicators of VA.