The effect of race on retinal oxygen metrics in subjects with and without diabetes

Abstract

Purpose : Diabetic retinopathy (DR) is a global threat to vision, with race impacting its incidence and severity. Previous studies have identified racial differences in retinal vessel caliber and oxygen saturation in DR. However, the association between race and retinal oxygen metrics (oxygen delivery (DO₂), metabolism (MO₂), and extraction fraction (OEF)) has not been reported. The purpose of this study was to test the hypothesis that retinal oxygen metrics vary according to race in subjects with and without diabetes.

Methods : The study included 97 subjects. The eyes (one per subject) were categorized into three groups: non-diabetic (ND; N=32), diabetic with no retinopathy (NDR; N=34), and mild non-proliferative DR (mild NPDR; N=31). Racial categorization comprised Asian (N=14), African-American (AA; N=15), non-Hispanic White (NHW; N=19), and Hispanic (N=49) groups. Retinal vascular oxygen saturation and blood flow were measured using our oximetry and Doppler optical coherence tomography techniques, respectively. From these measurements, DO₂, MO₂, and OEF were calculated. Statistical analysis included X² test for comparing categorical variables (age, sex, and race) and general linear model analysis to determine the effects of race and group on DO₂, MO₂, and OEF.

Results : Age, sex, and race did not significantly differ among groups (p≥0.25). Race and group interaction on DO₂ was not significant (p=0.08) and the main effect of race on DO₂ was significant (P=0.04). DO₂ was lower in NHWs than in AAs and Hispanics (p≤0.03). Interaction between race and group on MO₂ was significant (p=0.03). In mild NPDR, MO₂ was higher in Asians compared to AAs, NHWs, and Hispanics (p≤0.02), and also higher in Hispanics than in NHWs (p=0.02). In Asians, MO₂ was higher in mild NPDR than in NDR (p=0.01), while in NHWs, MO₂ was lower in mild NPDR compared to NDR (p=0.04). Race and group interaction on OEF was not significant (p=0.30) and OEF differed among races (P=0.01). OEF was higher in Asians than in AAs, NHWs, and Hispanics (p<0.02). The main effect of the group on DO₂ and OEF was not significant (P>0.80).

Conclusions : The study revealed differences in retinal oxygen delivery, metabolism, and extraction fraction among racial groups in non-diabetics and diabetics subjects with no or early clinical DR. These findings underscore the importance of considering race for evaluating retinal oxygen biomarkers for diagnosis and monitoring of DR.

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