Biomarkers on optical coherence tomography angiography associated with macular edema or ellipsoid zone defect in diabetic retinopathy

Abstract

Purpose : To identify the biomarkers on optical coherence tomography angiography (OCTA) en face images associated with diabetic macular edema (DME) or ellipsoid zone defect (EZD). In our previous study, we had successfully segmented larger vessels from retinal superficial microvasculature in both healthy eyes and eyes with diabetic retinopathy, thus, we could separately analyze the metrics of retinal larger vessels and capillaries in this study.

Methods : This is a cross-sectional study. 54 eyes from 31 patients (10 females, 31 Asians) with severe non-proliferative diabetic retinopathy (sNPDR, 25 eyes) or proliferative diabetic retinopathy (PDR, 29 eyes) were enrolled in this study. All eyes underwent a 3×3mm OCTA scan (Angioplex 10.0, Cirrus HD-5000) centered on the fovea. DME was defined as retinal thickening (with or without intraretinal cyst) or presence of subretinal fluid on B-scans. EZD was defined as loss of ellipsoid zone at least 250μm in length on B-scans. Binary logistic regressions (forward) were used for the study. The independent variables were age, gender, stage of DR and some features on OCTA en face images, which included presence of suspended scattering particles in motion (SSPiM) on either superficial capillary plexus (SCP) or deep capillary plexus (DCP) en face images (for EZD but not DME evaluation), number of microaneurysm (MA) in the whole retinal capillary plexus, foveal avascular zone (FAZ) area (mm²) of SCP, perfusion density (PD), vessel length density (VLD) (mm^-1) and vessel diameter index (VDI) (μm) for capillaries and larger vessels of SCP respectively.

Results : Of the 54 studied eyes, 31 (57%) eyes had DME and 21 (40%) eyes had EZD. Multivariate regression model showed that PDR (β=24, 95%CI:3-188, P=0.003), more MA (β=2, 95%CI:1-4, P=0.002) and increased VDI of larger vessels (β=2, 95%CI:1-3, P=0.046) were risk factors for DME. As for EZD, presence of SSPiM (β=5, 95%CI:1-20, P=0.028, larger FAZ area (β=27, 95%CI:1-1019, P=0.077) and increased VDI of capillaries (β=2, 95%CI:1-5, P=0.040) were risk factors.

Conclusions : In eyes with diabetic retinopathy, dilation of retinal larger vessels was associated with macular edema while dilation of retinal capillaries was associated with ellipsoid zone defect.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.