Inter-Eye Differences of Vessel Density and Fractal Dimension in Diabetic Patients

Abstract

Purpose : To evaluate intraindividual microvascular inter-eye differences in diabetic patients with same stage diabetic retinopathy (DR) in both eyes as assessed using optical coherence tomography angiography (OCTA).

Methods : In this cross-sectional study, fovea-centered swept-source 6x6mm OCTA scans were acquired using a 200kHz OCTA device. Vessel density (VD) and fractal dimension (FD) were calculated on binarized, vessel-segmented images in the superficial capillary plexus (SCP) and deep capillary plexus (DCP). Absolute difference (δ_abs) and asymmetry index between eyes was assessed and compared across DR stages by Kruskal-Wallis tests. Comparison of VD and FD between left and right side was done by linear mixed models.

Results : 336 eyes of 168 patients with DR stages ranging from mild non-proliferative to proliferative DR were included for analysis. The inter-eye comparison revealed significantly lower VD in the SCP (estimate [95% CI] =-0.009 [-0.01; -0.006], p<0.01) as well as a significantly lower FD in the SCP (-0.007 [-0.009; -0.005], p<0.01) of the left compared to the right eye. Inter-eye δ_abs and asymmetry index were higher in the IR compared to the OR in the SCP and DCP (p<0.01).

Conclusions : OCTA metrics provide important information on the retinal microvasculature in systemic diseases such as DR. Our results reveal a significant inter-eye difference with lower VD and FD in the SCP of the left compared to the right eye.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.

 

Binarized images of the superficial (left) and deep capillary plexus (right). Big vessels (highlighted in red) were excluded before analysis of vessel density and fractal dimension.