Association of Retinal Oximetry with Peripheral Diabetic Retinopathy Lesions and Nonperfusion on Ultra-widefield Angiography.

To evaluate the association of retinal ischemia measured using retinal oximetry with retinal nonperfusion and predominantly peripheral lesions on ultra-widefield (UWF) fluorescein angiography (FA PPL). Prospective single-center, image evaluation study. Images from 42 eyes from 21 participants with diabetes. Ultra-widefield images were evaluated to determine diabetic retinopathy (DR) severity. Ultra-widefield FA images were used to measure nonperfusion area (NPA, mm2) and nonperfusion index (NPI) and FA PPL presence. Retinal oximetry was performed to measure venous oxygen saturation (VO2, %) and arteriovenous difference (A-V, %) within a 2-disc diameter ring centered on the optic disc. Nonperfusion area, NPI, and presence of FA PPL. Mean age was 40.7 ± 10.4 years, diabetes duration 21.4 ± 10.0 years, hemoglobin A1c (HbA1c) 7.7 ± 1.0, 33.3% (14) were female, and 76.2% (32) had type 1. Distribution of DR on UWF color imaging was no-DR 9.5% (4); mild 45.2% (19), moderate 21.4% (9), and severe 9.5% (4) nonproliferative DR; and proliferative DR 14.3 (6) with FA PPL present in 25 (59.5%). Mean NPA/NPI was associated with increasing DR severity (P = 0.0014/0.0018), even after correction for diabetes duration and HbA1c (P = 0.0029/0.0025). In multivariate analysis adjusting for diabetes duration, HbA1c, and DR severity, the presence of FA PPL was associated with increasing VO2 and decreasing A-V (VO2; P = 0.03, A-V; P = 0.009). Past studies have established an increased risk of DR progression with the presence of FA PPL. These data show that FA PPL presence is associated with retinal oximetry measures consistent with the presence of venous shunting or reduced retinal oxygen consumption, possibly indicative of greater areas of retinal ischemia. These findings highlight the value of retinal oximetry as a noninvasive measure of retinal ischemia and as a potential marker for increased risk of DR worsening. Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.