Reliability and Determinants of Retinal Vessel Oximetry Measurements in Healthy Eyes

PURPOSE. To assess the reliability and determinants of retinal vessel oximetry measurements with the Oxymap T1 Retinal Oximeter in normal Asian eyes. METHODS. Subjects older than 40 years without a history of stroke and heart disease were recruited from a community-based clinic. Subjects underwent standardized systemic and ocular examinations. Normal eyes were defined as eyes without major eye diseases such as age-related macular degeneration, glaucoma, or retinopathy. Retinal vessel oximetry levels were measured by using the Oxymap T1 Retinal Oximeter. Intra-and intergrader reliability of retinal vessel oximetry measurements were assessed by using 50 images. Intravisit repeatability of retinal vessel oximetry measurements was assessed by using 20 paired images. Univariable linear regression was performed to examine the associations between retinal vessel oximetry measurements and systemic determinants. RESULTS. A total of 118 retinal oximetry images were included in the final analysis. Intra( intraclass correlation coefficient [ICC] values: 0.89-0.99) and intergrader (ICC values: 0.77-0.94) reliability, and intravisit (ICC values: 0.85-0.96) repeatability were both high. In the linear regression analysis, older age was associated with reduced overall retinal venular oximetry levels (beta: -2.61%; 95% confidence interval [CI]: -4.92 to -0.29) and reduced inferior-nasal retinal venular oximetry levels (b: -3.53%; 95% CI: -6.07 to -0.99). CONCLUSIONS. The Oxymap Retinal Oximeter allows reliable and repeatable retinal vessel oximetry measurements. Age is the main factor that influences retinal venular oximetry levels and should be taken into account when retinal oximetry measurements are interpreted.