Racial Variations in Retinal Oxygen Metabolic Biomarkers in Diabetic Retinopathy: A Pilot Study

Previous studies have reported that race affects the prevalence and progression of diabetic retinopathy (DR). In this pilot study, we tested the hypothesis that there are associations between race and retinal oxygen metabolic biomarkers in subjects without diabetes or with diabetes at early stages of DR.

A total of 104 subjects participated and were categorized into one of three diagnosis groups: nondiabetic (ND), diabetic without clinical DR (NDR), or diabetic with mild nonproliferative DR (mild NPDR). Subjects were also classified according to race as Asian (AS), African American (AA), Hispanic White (HW), or non-HW (NHW). Retinal oxygen metabolic biomarkers, namely, inner retinal oxygen delivery (DO₂), metabolism (MO₂), and extraction fraction (OEF), were determined by multimodal imaging (oximetry and Doppler optical coherence tomography).

There were significant interactions of race and diagnosis group on retinal oxygen metabolic biomarkers. The effect of diagnosis group on MO₂ was significant in the AS group, such that MO₂ was lower in the NDR than in mild NPDR. The diagnosis group did not have a significant effect on DO₂, OEF, or MO₂ in other races. In the ND group, there was no significant effect of race on MO₂, while DO₂ was marginally higher in HW than NHW. OEF was higher in AS than in HW and NHW. In the NDR group, there was no significant effect of race on OEF or MO₂, while DO₂ was higher in AA than AS, HW, and NHW. In mild NPDR, MO₂ and OEF were higher in AS than NHW, and DO₂ was not significantly affected by race.

The preliminary findings demonstrated associations of race with retinal oxygen metabolic biomarkers, underscoring the necessity for future studies in larger cohorts with the inclusion of potential confounding factors to establish normal baselines according to race that are needed for considering racial differences for clinical evaluation of DR.