Quantifying Peripapillary Microvascular Changes with Increasing Severity of Diabetic Retinopathy: An Optical Coherence Tomography Angiography (OCTA) Study

Abstract

Purpose : To determine the association between vessel density (VD) of the radial peripapillary capillaries (RPC) and severity of diabetic retinopathy (DR).

Methods : This prospective cross-sectional study included diabetic subjects with different stages of DR from a tertiary eye hospital in Hong Kong. DR severity was assessed by retinal specialists according to the international clinical diabetic retinopathy disease severity scale on dilated fundus examinations. Eyes with proliferative DR were excluded. All subjects underwent OCTA with a swept-source OCT (DRI-OCT Triton, Topcon, Inc, Tokyo, Japan). Slab of the RPC was extracted for image analysis. VD was measured by using an automated customized MATLAB program, with or without removal of large vessels. Linear mixed-effect model was used to determine the association bwtween VD and DR severity, adjusting for age, gender, duration of diabetes, axial length, HbA1c and inter-eye correlation.

Results : A total of 298 eyes (97 without DR, 87 with mild NPDR, 87 with moderate NPDR, 27 with severe NPDR) of 173 subjects were included in the final analysis. The average VDs were 61.47%, 60.65%, 59.71%, 57.17% in groups of eyes without, with mild, moderate and severe NPDR, respectively. We found a significant correlation between DR severity and VD in univariate (β=-0.011; P-trend<0.001; R²=0.453) and multivariate (β=-0.009; P-trend=0.003; R²=0.459) analysis. After removing large vessels, average VDs were 57.29%, 56.81%, 55.17% and 52.48% respectively. Associations between VD and DR severity remained statistically significant in both univariate (β=-0.013; P-trend<0.001; R²=0.483) and multivariate (β=-0.013; P-trend<0.001; R²=0.494) models.

Conclusions : VD of RPC is significantly associated with DR severity and the association become even stronger when large vessels are removed. A significant decline of VD of RPC with increasing DR severity implies its potential in monitoring disease progression in patient with diabetes.

This abstract was presented at the 2019 ARVO Imaging in the Eye Conference, held in Vancouver, Canada, April 26-27, 2019.

 

A-D: original images; E-F: binarization; I-L: denoising; M-P: quantification; VD_incLV: vessel density (large vessels included); VD_excLV: vessel density (large vessels removed).