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Assessing Retinal Non-Perfusion With Ultra-Widefield OCT-A: Correlations With Diabetic Retinopathy Severity and
Selin S Gumustop1, Xinyi Ding1, Yi Stephanie Zhang2
1From the Harvard Retinal Imaging Lab (S.S.G., X.D., I.P., Y.Z., L.W., F.R., I.G., C.C., K.N.N., S.H.S., S.L.W., J.B.M.), Department of Ophthalmology, Massachusetts Eye and Ear, Harvard Medical School, Boston, Massachusetts, USA.
Purpose:
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).
Design:
Cross-sectional, retrospective study.
Participants:
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.
Methods:
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.
Main Outcome Measures:
NPA and ISI from 12 × 12-mm and 21 × 26-mm scans and their association with DR severity.
Results:
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.
Conclusions:
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.
