Abstract
Purpose:
To test the hypothesis that oxygen saturation is altered in retinal arteries and veins in diabetic patients.
Methods:
A retinal oximeter (Oxymap ehf., Reykjavik, Iceland) was used to measure oxygen saturation in all major retinal arteries and veins in healthy subjects and in patients with and without diabetic retinopathy. Oxygen-sensitive (605 nm) and oxygen-insensitive (586 nm) wavelengths were employed by the retinal oximeter. The oxygen saturation values in all major arteries and veins in each subject were averaged and then all subject values in each category were averaged.
Results:
In healthy subjects, retinal oxygen saturation values for arteries and veins were 92.3 ± 4.2 and 57.2 ± 6, respectively (n=14). The analogous values in diabetic patients with no signs of retinopathy were 96.3 ± 8.6 and 58.7 ± 7.5 (n=45). In patients with varying degrees of pathology from mild to severe nonproliferative to proliferative retinopathy, these values were 99.8 ± 10 in arteries and 63.2 ± 8 in veins (n=48). The difference between healthy subjects and diabetic patients without and with retinopathy was statistically significant. The arterial p-values were 0.02 and 0.0001, respectively. The venous p-values were 0.4 and .03, respectively. The difference between all levels of retinopathy and no retinopathy in diabetic patients is significant only for a p-value of 0.03 for arteries. The corresponding p-value for veins is 0.07. All five subgroups of diabetic patients (non-diabetic-retinopathy, mild, moderate to severe nonproliferative diabetic retinopathy and proliferative diabetic retinopathy) had higher saturation values than healthy subjects.
Conclusions:
Based on our study, we believe the dual-wavelength retinal oximeter will significantly aid in the screening of DR by identifying those at risk for retinal vascular changes.
Keywords: 688 retina •
436 blood supply •
592 metabolism