A Comprehensive Assessment of Retinal Microvascular and Choroidal Alterations in Proliferative Diabetic Retinopathy using Swept-Source Optical Coherence Tomography Angiography (SS-OCTA)

Abstract

Purpose : To investigate the association between retinal microvascular and choroidal changes in proliferative diabetic retinopathy (PDR) using swept-source optical coherence tomography angiography (SS-OCTA).

Methods : In this cross-sectional observational study, 197 eyes of 135 patients with PDR underwent a complete ophthalmic examination, including 6x6 and 12x12-mm SS-OCTA centered on the macula (PLEX® Elite 9000, Carl Zeiss Meditec). OCT images were analyzed for diabetic macular edema, epiretinal membrane, central subfield thickness, and subfoveal choroidal thickness (SFCT). The Macular Density algorithm (v0.7.3.3) on the ARI Network (Zeiss Portal) was used to obtain vessel density (VD), vessel skeletonized density (VSD), and foveal avascular zone (FAZ) metrics in the superficial (SCP), deep (DCP) capillary plexuses, and the whole retina (WR) of the OCT angiograms. Ischemic index (ISI – the ratio between nonperfused and total retinal area) and the percentage of inner choroidal flow deficit (ICFD%) in the central 3- and 5-mm circles were measured with FIJI (NIH; Bethesda, MD) starting from 12x12 and 6x6-mm scans, respectively. Multivariate mixed-effects regression models controlling for age were employed for the analysis.

Results : The median age of our cohort was 58.0 (50.0-65.5) years, and there were 50 female patients (38.2%). Greater ISI was associated with reduced VD and VSD in the SCP and WR of 6x6-mm scans (all p<0.05). Several correlations were found between retinal vascular metrics, ICFD%, and SFCT. Greater ICFD% in the 3-mm and 5-mm central circles was significantly associated with greater SFCT (p=0.01 and p=0.02, respectively) and with higher VD and VSD in the DCP of 6x6 mm scans (p<0.05 for each). Additionally, greater SFCT was significantly associated with (1) higher VSD of the SCP (p=0.03), DCP (p=0.01) and WR (p=0.03) and with (2) higher VD of the SCP (p=0.01), DCP (p=0.01), and WR (p=0.02).

Conclusions : Our study reveals that significant associations exist between retinal microvasculature and choroidal alterations in patients affected by PDR. These results underscore the utility of SS-OCTA metrics in quantifying retinal and choroidal changes in PDR, with potential implications for prognosis, stratification, and management of these patients.

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