Retinal oxygen saturation changes progressively over time in diabetic retinopathy.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked DownloadPurpose: According to cross-sectional studies, oxygen saturation is elevated in retinal vessels in diabetic patients. We evaluated how retinal oxygenation (metabolic marker), vessel diameters and retinopathy grade (structural markers) change over time in diabetic patients. Design: Prospective cohort study following screening in a hospital setting. Methods: Retinal oximetry images were acquired in 214 patients with the Oxymap T1 oximeter. Imaging was repeated after a median of 3.0 years (range 0.76-6.8 years). Oxygen saturation and vessel diameters were measured in the right eye. Semiquantitative grading of retinopathy according to international guidelines and red lesion count were performed on fundus photographs. Results: Retinopathy grade according to the international semiquantitative grading system was unchanged. Arteriolar saturation increased by 0.75±0.15 percentage points per year of follow-up (p0.44). Conclusions: Oxygen saturation in larger retinal vessels can increase and arteriovenous difference can decrease over time in diabetic patients without any observable changes in retinopathy grade. The results suggest that changes in retinal oxygen saturation may precede progression of diabetic retinopathy or that oxygen saturation is more sensitive to disease progression than retinopathy grade.Icelandic Center for Research Toyota Foundation University of Iceland Research Fund Helga Jonsdottir and Sigurlidi Kristjansson Memorial Fun