Optical Coherence Tomography-Angiography and Ultrawide Field Fluorescein Angiography Imaging of non-perfusion in Diabetic Retinopathy: Macula vs Periphery

Abstract

Purpose : To investigate the association between peripheral non-perfusion index(NPI) on ultrawide-field fluorescein angiography(UWF-FA) and quantitative OCT-Angiography(OCT-A) metrics in the macula at different diabetic retinopathy(DR) stages.

Methods : Of 259 DM patients with full systemic history and UWF-color fundus photos (CFP) in two clinical centres, 48 also had UWF-FA (California, Optos) and OCT-A (Spectralis, Heidelberg). DR severity and presence of predominantly peripheral lesions(PPL) were evaluated by two independent graders. OCT-A(3x3 mm) was used to determine foveal avascular zone(FAZ) parameters and vessel and perfusion density(VD, PD), fractal dimension(FD) on superficial capillary plexus. NPI on UWF-FA was calculated as non-perfusion area(NPA) divided by total gradable area(TA). A centralized reading center graded all images for NPA/TA, using customizable Optos measurement tool. NPI’s extent and distribution were determined within fovea centered concentric rings corresponding to posterior pole (<10 mm), mid-periphery (10-15 mm), and far-periphery (>15 mm). NPI was also determined within the total retinal area, the central macular field (6x6 mm), ETDRS fields and within each extended ETDRS field (P1-P7).

Results : 42 eyes had non-proliferative DR(5 mild, 29 moderate, 8 severe); 6 had proliferative DR. PPLs were not associated with NPI on UWF-FA. Macular PD was significantly correlated to NPI in total area of retina (Spearman r=0.69), posterior pole (r=0.48), mid-periphery (r=0.65), far-periphery (r=0.59), p<0.05 for each; P3-P7 (r=0,55 at least, p<0.05 for each), central macula (r=0.47), total area in ETDRS (r=0.55), p<0.05 for each. Macular VD and FD were correlated to NPI of total area of the retina (r=0.60 and 0.61, p<0.05), the mid-periphery (r=0.56, p<0.05) and far-periphery (r=0.60 and r=0.61, p<0.05), and in P1-P7 (p<0.05). FAZ perimeter was corelated to NPI at posterior pole and central macular area (r=0.37 and 0.36, p<0.05), and FAZ area to NPI in central macular area (r=0.36, p<0.05).

Conclusions : Perfusion macular metrics on OCT-A were correlated with UWF-FA-NP, particularly in the mid and far retina's periphery.OCT-A might be a useful non-invasive method to estimate peripheral retinal NP. Further studies would be needed to assess OCT-A usefulness in evaluation of progression of NP and prediction of peripheral involvement.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.