Increased Retinal Oxygen Metabolism Precedes Microvascular Alterations in Type 1 Diabetic Mice

PURPOSE: To investigate inner retinal oxygen metabolic rate (IRMRO(2)) during early stages of type 1 diabetes in a transgenic mouse model. METHODS: In current study, we involved seven diabetic mice (Akita/+, TSP1(−/−)) and seven control mice (TSP1(−/−)), and applied visible-light optical coherence tomography (vis-OCT) to image functional parameters including retinal blood flow rate, oxygen saturation (sO(2)) and the IRMRO(2) value longitudinally from 5 weeks of age to 13 weeks of age. After imaging at 13 weeks of age, we analyzed the imaging results, and examined histology of mouse retina. RESULTS: Between diabetic mice and the control group, we observed significant differences in venous sO(2) from 9 weeks of age (P = 0.006), and significant increment in IRMRO(2) from 11 weeks of age (P = 0.001) in diabetic mice compared with control group. We did not find significant differences in retinal blood flow rate as well as arterial sO(2) during imaging between diabetic and control mice. Histologic examination of diabetic and control mice at 13 weeks of age also revealed no anatomical retinal alternations. CONCLUSIONS: In diabetic retinopathy, complications in retinal oxygen metabolism may occur before changes of retinal anatomical structure.