To evaluate the association of microvascular lesions on ultra-widefield (UWF) color-fundus (CF) images with retinal nonperfusion (RNP) up to the midperiphery on single-capture widefield (WF) optical coherence tomography angiography (OCTA) in patients with diabetic retinopathy (DR).
Cross-sectional study.
Seventy-five eyes of 50 patients with mild to severe non-proliferative DR (NPDR) and proliferative DR (PDR) were included in this analysis.
DR stage (Early Treatment Diabetic Retinopathy Study; ETDRS) and presence of predominantly peripheral lesions (PPL) were assessed on UWF-CF images acquired with a Zeiss Clarus 700. Single-capture 65°-WF-OCTA was performed using a PlexElite prototype (Carl Zeiss Meditec Inc.). A custom grid consisting of a central ETDRS grid extended by two rings reaching up to the midperiphery was overlaid to subdivide retinal areas visible on WF-OCTA en-face images. RNP was measured in each area and in total. Nonperfusion index (NPI) was calculated from total RNP. On UWF-CF images the number of microaneurysms, hemorrhages, neovascularizations, and areas with intraretinal microvascular abnormalities (IRMAs) were evaluated using the same grid.
Association of diabetic lesions with RNP was calculated using Spearman correlations (r).
Median RNP on WF-OCTA was 0mm (0-0.9), 4.9mm (1.9-5.4), 23.4mm (17.8-37), and 68.4mm (40.8-91.7) in mild, moderate, severe NPDR and PDR, respectively. We found a statistically significant correlation (p<0.01) of overall RNP (r=0.96,) and NPI (r=0.97) on WF-OCTA with ETDRS level. Number of grid-fields affected by IRMAs on CF images was highly associated with NPI (r=0.86, p<0.01). IRMAs and RNPs had similar topographic distributions with high correlations in affected areas. Eyes with PPL (n=43 eyes, 57%) on CF-images had a significantly higher NPI (p=0.014) than eyes without PPL.
The combination of UWF-CF imaging and single-capture WF-OCTA allows precise and non-invasive analysis of the retinal vasculature up to the midperiphery in patients with DR. The presence and extent of IRMAs on CF images may serve as an indicator for underlying RNP, which is more pronounced in eyes with PPL.
Copyright © 2023. Published by Elsevier Inc.
