Test-retest repeatability in macular retinal oximetry.

CLINICAL RELEVANCE: Evaluation of retinal macular oxygen saturation in healthy controls can aid in understanding the pathological changes seen in similar locations of those with vascular diseases like diabetes. BACKGROUND: The aim of this study was to determine the test-retest repeatability of localised retinal oximetry measurements in the macula on the Zilia Oximeter within healthy subjects of different races, 18-40 years old. Oxygen saturation was measured between three time points within the same locations of the right eye. METHODS: Twenty seven subjects were included (aged 26.3 ± 3.6 years). All were confirmed to have healthy retinas and at least 6/9 vision. Oximetry measurements were taken using the Zilia to acquire local oxygen saturation measurements (300 µm diameter) at four points 3.1 degrees from the fovea in the superior/temporal, superior/nasal, inferior/temporal, and inferior/nasal locations. Oximetry measurements were taken twice on the same day 20 minutes apart and then again 1-2 weeks later. Oximetry data was analysed with intraclass correlation between visits. To assess intrasubject repeatability, the Bland-Altman repeatability coefficient and coefficient of variation were calculated. RESULTS: Average Intraclass correlation for the three acquisition times of the right eye was 0.78. The averaged intrasubject repeatability coefficient for the three acquisition times was 8.4. The averaged coefficient of variation was 5.4%. CONCLUSION: The Zilia oximeter has good macular test-retest repeatability; however, multiple measurements may be needed to ensure accuracy.