Abstract
Purpose :
Diabetic retinopathy results in neural and vascular dysregulation leading to vision loss. Changes in retinal oxygen saturation (O2S) are part of this pathway, but to date have not been evaluated locally in the macula. The purpose of this study is to evaluate local measures of retinal O2S and vessel density at multiple matched retinal locations in the macula outside the foveal avascular zone (FAZ), and compare these results in controls, subjects with prediabetes and subjects with diabetes (DM), both with and without retinopathy.
Methods :
Fifty subjects (age 52.9 ± 9.9) were analyzed (16 controls, 8 prediabetes, 19 DM without retinopathy (DMnR), and 7 DM with retinopathy (DMR)). Medical health demographic data, HbA1c (Siemens Analyzer), and fundus photography were taken for all subjects to ensure accuracy of grouping. Retinal oximetry (Zilia) was performed within four quadrants adjacent to the FAZ within a 300um target (superior/temporal, superior/nasal, inferior/temporal, and inferior/nasal). Optical coherence tomography angiography (OCTA) was completed (Zeiss) and corrected for refractive error. Images from both instruments were aligned using Photoshop. OCTA vessel density was obtained with ImageJ. O2S and OCTA were analyzed overall and by region with regression and cluster analysis. Differences in groups were found with corrected t-tests.
Results :
A significant inverse correlation was observed between averaged retinal O2S and OCTA measures (p = 0.008) for all subjects. No significance was observed with local measures (p = 0.06) using cluster regression analysis but did trend toward the same inverse correlation. O2S measures were significantly higher in DMR (70.2% ± 14.3) compared to the other groups (control 54.7% ± 14.2, prediabetes 57.2% ± 8.9, DMnR 57.2% ± 13.6), (P<0.001). Duration of DM was significantly associated with retinal oximetry (p = 0.05), but not OCTA (p = 0.16).
Conclusions :
This study indicates retinal O2S could be an early sensitive metric in measuring the retinal health of those with DM. The correlation between averaged retinal O2S and OCTA needs longitudinal studies to see if reduced vessel density activates an increase in retinal O2S. A larger sample of DM subjects with retinopathy is needed to fully understand these relationships and strengthen the evaluation of local macular comparisons in regions at risk for vision loss.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.