Macular Oxygen Saturation in Normal, Non-proliferative, and Proliferative Diabetic Retinopathy Subjects Using Visible Light Optical Coherence Tomography

Abstract

Purpose : Diabetic retinopathy (DR) is a leading cause of blindness worldwide, and ultimately is a vasculopathy in retina. While the macula is often impaired in DR, the macular blood oxygen saturation (sO₂) in DR remains unexplored. This study aims to investigate and compare sO₂ levels within microvasculature at macular region among individuals with normal retinas, non-proliferative diabetic retinopathy (NPDR), and proliferative diabetic retinopathy (PDR).

Methods : A cross-sectional study was conducted involving 46 eyes of 32 subjects divided into three groups: 16 eyes of 10 individuals with normal retinas, 18 eyes of 13 with NPDR, and 12 eyes of 9 with PDR. We utilized retinal oximetry of visible light optical coherence tomography (VIS-OCT) to measure the sO₂ in macular vessels. The imaging protocol employed raster scanning with a sample density of 512*256, covering an area of 5 mm by 5 mm. We calculated the sO₂ of arterioles (AsO₂), venules (VsO₂), the difference between arterioles and venules (A-V sO₂=AsO₂-VsO₂). We collected the relevant clinical and demographic data. ANOVA and post-hoc tests were performed to assess differences in retinal sO₂ among the three groups. Spearman correlation tests were used to correlate sO₂ markers to clinical data such as central subfield thickness and macular volume.

Results : Figure 1 illustrates the statistical comparisons of sO₂ among three groups. Significant variations were observed among the normal, NPDR, and PDR groups for AsO₂, VsO₂ and A-V sO₂ with an increasing trend in VsO₂ and a decreasing trend in A-V sO₂. The correlation between VsO₂ and macular volume was found to be significant.

Conclusions : This study provides insights into the macular sO₂ changes among individuals with normal retinas, NPDR, and PDR. The observed differences may hold implications for understanding the pathophysiology of diabetic retinopathy and could contribute to the development of targeted interventions.

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

 

Figure 1. Statistical comparisons among normal (abbreviated as H), NPDR and PDR groups. (a-c) AsO₂, VsO₂, A-VsO₂. One-way ANOVA was performed first, then multiple comparison within groups was to calculate the p value. ns, not significant, p>0.05. *, p<0.05. **, p<0.01. ***, p<0.001 ****, p<0.0001.