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.