Assessing Retinal Non-Perfusion With Ultra-Widefield OCT-A: Correlations With Diabetic Retinopathy Severity and Peripheral Lesions.

Abstract

To compare non perfusion area (NPA) and the ischemic index (ISI) between 2 fields of view using ultra-widefield optical coherence tomography angiography (UWF-OCTA) and evaluate their correlation with diabetic retinopathy (DR) severity and predominantly peripheral lesions (PPL). Cross-sectional, retrospective study. Sixty-two patients (101 eyes) with DR without prior pan-photocoagulation (PRP) treatment, imaged with 12 × 12-mm and 21 × 26-mm scans on UWF-OCTA. Forty-nine patients (79 eyes) with same-day ultra-widefield color fundus photography (UWF-CFP) were included in the PPL analysis. NPA was calculated from UWF-OCTA scans using a semi-automatic algorithm on FIJI. ISI was determined as NPA divided by total scan area. A subset of eyes with same-day UWF CFP were assessed by 2 graders for the presence and extent of fields with PPLs - defined as >50% of diabetic lesions in extended versus Early Treatment of Diabetic Retinopathy Study (ETDRS) fields. Eyes were classified as having PPLs if ≥ 1 field met this criterion. NPA and ISI from 12 × 12-mm and 21 × 26-mm scans and their association with DR severity. NPA and ISI were significantly greater in PDR versus NPDR for both scans and the NPA/ISI was significantly higher in the 21 × 26-mm scan (P < .001 for all). Both the 12 × 12-mm (OR: 1.26 [95% CI: 1.07-1.48, P = .006]) and the 21 × 26-mm ISI (OR: 1.20 [95% CI: 1.10-1.29, P < .001]) were significantly associated with increasing DR severity. ROC analysis showed similar performance between both scan ISI at predicting DR severity (AUC: 0.868 vs 0.878, P = .558). In the sub-analysis, presence of PPL was only significantly associated with ISI on the 21 × 26-mm scan (B = 0.43901, P = .009). However, the interaction of both presence (B = 0.16, P = .006) and extent (B = 0.2,5 P = .044) of PPLs with increasing DR severity was positively associated with increasing ISI on the 21 × 26-mm scan. NPA/ISI on both the 12 × 12-mm and 21 × 26-mm scans is predictive of DR severity, highlighting the importance of OCTA detection of ischemia. The wider scan area of the 21 × 26-mm scan can better assess far peripheral ischemia that correlates with PPLs, supporting its potential role in tracking DR progression.