Racial differences in optical coherence tomography angiography (OCTA) parameters between older non-diabetics

Abstract

Purpose : Black populations face higher rates of diabetes (DM) and vision loss from diabetic retinopathy, even after controlling for known risk factors. While we have found differences in OCTA parameters between young healthy black and white subjects, the effect of aging is unknown. The purpose of this prospective cross-sectional study is to use OCTA to determine if there are differences in the chorioretinal capillaries of older black and white non-DM subjects.

Methods : OCTA (Optovue RTVue XR Avanti) was used to image 40 eyes from 27 black non-DM patients (mean age 56.9±14.4y) and 46 eyes from 30 white non-DM patients (mean age 51.7±16.1y). At baseline, there were no significant differences in age (p=.86), gender (p=.17), or image signal strength (p=.45). Subjects had similar baseline systemic comorbidities including hyperlipidemia, heart disease, smoking pack-years, but not hypertension. Built-in software was used to measure vessel density (VD) at the superficial (SCP), middle (MCP), and deep capillary plexuses (DCP); the foveal avascular zone (FAZ) area, perimeter, acircularity index (AI), and FD-300; and the percentage of blood flow area (%BFA) in the choriocapillaris. A mixed-effects regression model, controlling for 2 eyes of the same patient and hypertension, was used to determine the association between race and OCTA parameters.

Results : Within the SCP and MCP, black subjects had lower foveal VD compared to white subjects (15.03±7.54% vs 21.07±8.07%, p=.02) and (28.03± 8.19% vs 35.44±6.51%, p<.001, respectively). No differences were observed at the DCP. Black subjects had a larger FAZ area (.35±.12mm² vs .23±.10mm², p<.001), FAZ perimeter (2.38±.39mm vs 1.88±.44mm, p<.001) and larger FD-300, a measurement of VD in a 300 μm wide region around the FAZ (51.21±3.76% vs 49.2±3.53%, p=.001). Black subjects had a lower %BFA at the fovea, parafovea, and the 3x3mm area (p=.04, p=.008, p=.006, respectively).

Conclusions : To our knowledge, this is the first report of differences in OCTA parameters between older black and white non-DM adults. Decreased blood flow in the fovea and choriocapillaris, as well as a larger FAZ in older black adults, may contribute to a higher susceptibility to diabetic vascular damage, while highlighting the need for normative databases and racially diverse clinical studies. Further studies are needed to elucidate the role of racial differences in OCTA parameters.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.