Clinical Optometry (Jul 2024)
Variations in Retinal Oxygen Saturation in a Diverse Healthy Population
Abstract
Kelly K Bisignano, Jennyffer D Smith, Wendy W Harrison Department of Clinical Sciences College of Optometry, University of Houston, Houston, TX, USACorrespondence: Wendy W Harrison, Email [email protected]: Local retinal oxygen saturation is a research technique, which has the potential as a biomarker for diabetes. However, normative data has not been established. This study examined differences in oxygen saturation around the macula and characterizes the relationship between age, race, refractive error (RE), sex, blood pressure (BP), prediabetic status and oxygen saturation.Methods: Fifty-nine subjects aged 22– 69 (38.8 ± 14.7 years) were included who were racially diverse and with equal gender distribution. None had eye disease. Oxygen saturation was taken with the Zilia Ocular in 4 locations around the macula 3.1 degrees from the fovea and they were also averaged. BP, RE, and HbA1c were noted. Regression analyses for oximetry and other factors were completed as were t-tests with multiple comparison corrections.Results: There were significant variations in oximetry measures by race, with higher pigmentation levels associated with lower oximetry values (p < 0.01). There was no relationship between oximetry and sex (p = 0.34), RE (p = 0.67), BP (systolic p = 0.61, diastolic p = 0.71) nor prediabetic status (p = 0.87). Oximetry was associated with age when controlling for race (P < 0.002). Nasal-temporal variations showed nasal oximetry to higher than temporal measures (P < 0.01).Conclusion: This study revealed race/pigmentation is an important influence on oximetry measures. Retinal location also caused variations, likely due to proximity to larger vessels nasally. No differences in sex, RE nor BP were observed to alter local oxygen saturation. However, age was correlated when considered with race. This study will inform our future work in different disease states and is an important first step in evaluating this technology.Plain Language Summary: This study evaluates a new research instrument (Zilia Ocular) which measures how much oxygen is in the very small blood vessels of the retina. Our group wanted to evaluate healthy people to find out if the measurements the instrument takes are different in different sexes, ages, races, glasses prescriptions and blood pressures. We also looked at if they were changed in people with prediabetes and if it is different in different locations on the retina. We found that the measures are different in different races and ages. The measures also change with location in the eye. The other factors did not change the measurements of oxygen saturation on this instrument. We need to know this information because we want to detect changes in the retina in diabetes in diverse patient groups; however, we need to know about normal variations to better understand and collect that data.Keywords: oximetry, oxygen saturation, prediabetes, refractive error, blood pressure
