Abstract Background/objectives To determine the topographic distribution of retinal non-perfusion (RNP) progression in patients with severe non-proliferative diabetic retinopathy (sNPDR) and proliferative diabetic retinopathy (PDR). Subjects/methods This retrospective study was conducted at Moorfields Eye Hospital in the United Kingdom. Patients with diabetic retinopathy (DR) who had two sets of ultra-widefield fundus fluorescein angiography were included. A grid comprising seven concentric rings was superimposed on the images. RNP areas were annotated using Optos’ proprietary tool. Total and zonal non-perfusion index (NPI) were calculated as the RNP area divided by the gradable retinal area. Adjusted linear mixed-effects models (LMEMs) were used to estimate progression, accounting for repeated measures and inter-eye correlation. Results A total of 53 patients (67 eyes) were included in the analyses. This cohort comprised 19 (28%) eyes with PDR, 31 (46%) with sNPDR, and 17 (25%) with mild-to-moderate NPDR. Focusing on sNPDR and PDR, the nasal 20-30 mm zone had the largest NPI (0.37 ± 0.26) at baseline. Over time, the total NPI increased significantly, with an estimated change of +0.027 (12.42 mm²) per year (95% confidence interval CI = 0.008 to 0.045, P = 0.005). The inferior 10–20 mm ring showed the fastest NPI progression ( + 0.049/year; P = 0.007). Conclusions This study demonstrates that NPI increased with time in DR. Notably, the inferior 10-20 mm zone was most vulnerable to NPI progression. Of note, this study was limited by the confounding effect of anti-vascular endothelial growth factor (anti-VEGF) treatment; therefore, a future prospective study to control for treatment exposure would be warranted.
Tsai et al. (Sat,) studied this question.