NORMATIVE VALUES AND PREDICTORS OF RETINAL OXYGEN SATURATION

Purpose: To determine normal retinal oxygen saturation (SO2) values measured with retinal oximetry in a multiethnic group of healthy subjects and to evaluate the association of retinal SO2 with demographic and clinical parameters. Methods: Retinal oximetry was performed in both eyes of 61 normal healthy subjects. Global and quadrant venous (SvO(2)) and arterial oxygen saturation (SaO(2)), arteriovenous difference in SO2, and venular and arteriolar width were measured. The association of SO2 parameters with age, gender, ethnicity, refraction, iris color, history of controlled systemic hypertension, and smoking was analyzed. Results: Average SvO(2) and SaO(2) were 55.3 +/- 7.1% and 90.4 +/- 4.3%, respectively. All average measurements were comparable in both eyes, both genders, and among ethnic groups. Inferonasal quadrant SaO(2) was higher in Asians. Age was associated with decreased SvO(2) (b = -0.19; P = 0.001) and SaO(2) (b = -0.11; P = 0.003). History of controlled systemic hypertension was associated with an increase in arteriovenous difference in SO2 (b = 3.99; P = 0.013). Conclusion: This is the first description of retinal SO2 in healthy, multiethnic subjects. Aging decreases SvO(2) and SaO(2) and should be accounted for when interpreting retinal oximetry measurements. Other demographic and clinical parameters studied did not seem to significantly influence retinal SO2 measurements.