Retinal arterial and venous oxygen saturation is altered in diabetic patients.

PURPOSE To determine the retinal oxygen saturation trend with onset of diabetes and increasing severity of diabetic retinopathy by comparing diabetic groups with and without retinopathy to controls. METHODS A fundus camera-based dual-wavelength snapshot oximeter imaged retinas of healthy subjects and patients with and without diabetic retinopathy. The images were analyzed to determine oxygen saturation in major retinal arteries and veins, which is inversely proportional to optical density ratio. RESULTS Control retinal oxygen saturation (n = 14) in arteries was 92.3 ± 4.2% and in veins, 57.2 ± 6.0%. Retinal oxygen saturation for diabetic patients with no signs of diabetic retinopathy (NDR, n = 45) in arteries was 96.3 ± 8.6% (P = 0.662) and in veins, 58.7 ± 7.5% (P = 0.998). Retinal oxygen saturation for diabetics with mild to moderate nonproliferative diabetic retinopathy (NPDR, n = 23) in arteries was 97.7 ± 5.8% (P = 0.590) and in veins, 61.1 ± 7.6% (P = 0.658). Retinal oxygen saturation for diabetics with severe NPDR (n = 12) in arteries was 102 ± 10.2% (P = 0.023) and in veins, 66.8 ± 8.4% (P < 0.001). Retinal oxygen saturation for patients with proliferative diabetic retinopathy (PDR, n = 13) in arteries was 103.6 ± 8.7% (P = 0.003) and in veins, 66.6 ± 10.2% (P = 0.026). Retinal oxygen saturation for all diabetics with retinopathy combined (all DR, n = 48) in arteries was 100.4 ± 7.6% (P = 0.004) and in veins, 64.2 ± 8.4% (P = 0.007). CONCLUSIONS A trend of increasing retinal oxygen saturation was found from controls to NDR group to increasing levels of diabetic retinopathy, though significance was only reached for the comparison of controls to severe-NPDR, PDR, and all-DR groups.