Associations of retinal oximetry in persons with diabetes

BackgroundThere are limited data available on the variables that might affect retinal vessel oxygen saturation (SO2) in diabetes. Therefore, the aim of this study is to assess factors associated with retinal oximetry values in persons with diabetes. DesignClinic-based cross-sectional study. ParticipantsFifty-eight persons with diabetes aged 18+ years, recruited from the University of Melbourne, the Royal Victorian Eye and Ear Hospital, and St. Vincent's Hospital (Melbourne), Australia. MethodsRetinal oximetry was performed using the oximetry module of the Vesselmap system (Imedos UG, Jena, Germany) in 92 diabetic eyes. Generalized estimating equation models were used to estimate the associations between candidate variables (age; gender; retinal capillary flow; duration of diabetes; hypertension; smoking status; presence of diabetic retinopathy [DR]; glycated haemoglobin; triglyceride; total cholesterol; finger SO2 and ocular perfusion pressure) with retinal oximetry measures. Main Outcome MeasureArteriolar SO2, venular SO2 and the arterio-venous (A-V) difference. ResultsOf the candidate factors assessed, only the presence of DR was significantly associated with increased venular SO2 and decreased A-V difference in unadjusted analyses. In models adjusting for age and gender and significant variables from unadjusted analyses, compared with no DR, the presence of DR was significantly associated with greater retinal venular SO2 values (=3.65%, 95% confidence interval: 0.67-6.63%) and decreased A-V difference (=-2.00%, 95% confidence interval: -3.46 to -0.53%). ConclusionIn patients with diabetes, eyes with DR were associated with increased venular SO2 and decreased A-V difference compared with eyes without DR, suggesting an altered metabolic state in DR.