Relating Retinal Vascular Oxygen Saturation and Microvasculature Morphology at Progressive Stages of Diabetic Retinopathy

Abstract

Purpose Diabetic retinopathy (DR) is a common cause of vision loss in working age adults and presents changes in retinal vessel oxygenation and morphology. The purpose of this study was to test the hypothesis that there is an association of retinal vessel oxygen saturation with vessel density (VD) and tortuosity in DR. Methods Ninety-five subjects were classified in the following groups: nondiabetic control ( N = 25), no DR ( N = 28), mild nonproliferative DR (NPDR; N = 21), moderate to severe NPDR ( N = 14), or treated proliferative DR (PDR; N = 7). Retinal oximetry was performed to measure arterial and venous oxygen saturation (SO 2A and SO 2V ) and calculate oxygen extraction fraction (OEF). Optical coherence tomography angiography (OCTA) was performed for measurements of VD and vessel tortuosity index (VTI). Results There were statistically significant differences in SO 2A and SO 2V among groups ( P < 0.004). SO 2A and SO 2V were higher in the PDR group compared to the control group and SO 2V was also higher in the moderate to severe NPDR group. VD differed significantly among groups ( P = 0.003), whereas VTI was not significantly different ( P = 0.22). Compared to the control group, VD was lower in moderate to severe NPDR and PDR groups. VD was also lower in the PDR group than that in the no DR group ( P = 0.03). There was a significant correlation of VTI with SO 2V (r = 0.32, P = 0.002) and OEF (r = −0.35, P = 0.001). Conclusions Retinal vessel morphology, oxygenation, and tissue oxygen extraction were associated with each other in a cohort of subjects with and without DR. Translational Relevance The findings of this study have the potential to improve clinical management of DR by providing better understanding of human disease pathophysiology and propelling future studies to identify multiple image-based biomarkers for improved disease diagnosis and monitoring.

The retinal oxygen metabolism and hemodynamics as a substitute for biochemical tests to predict nonproliferative diabetic retinopathy

“…Previously, most studies have used SO 2 to indirectly observe abnormal oxygen metabolism in DM. In our study, we found SO 2 A and SO 2 V increase gradually, and SO 2 A_V increases first and then decreases with the development of DM, which is consistent with previous studies [8,11,12,31]. There are several reasons to explain SO 2 change in DM, including the thickening of vessel walls to decrease oxygen diffusion, high levels of HbA1c to retain the oxygen in the vessel, blood shunting and bypassing of nonperfused areas [32].…”

“…However, literature findings on retinal SO 2 between DM without DR (NDR) and NPDR were inconsistent. Compared to NDR, some studies demonstrated significantly increased venular SO 2 in NPDR [8,9], while other studies found no significant change in retinal SO 2 [10][11][12]. Nevertheless, it should be noted that it is not comprehensive to evaluate SO 2 alone since it only indicates the percentages of oxyhemoglobin in the blood.…”

Decreased macular choriocapillaris in thyroid-associated ophthalmopathy: focusing on chorioretinal folds with and without optic disc edema

“…OCTA, a novel noninvasive technique, was recently adopted to quantitatively measure retinal and choroidal microvasculature in different ocular and systemic diseases, such as glaucoma (27,28), age-related macular degeneration (29-31), optic neuropathies (32-35), leukemia (36), diabetic retinopathy (37)(38)(39)(40), and TAO (14,19,20,41,42), and to evaluate the severity and prognosis of these diseases. Our study showed that the macular retinal VD was significantly decreased in the ODE and NODE groups compared with the normal group.…”