Retinal Oxygen Metabolism in Patients With Type 2 Diabetes and Different Stages of Diabetic Retinopathy

摘要

The aim of this cross-sectional study was to assess retinal oxygen metabolism in patients with type 2 diabetes and different stages of nonproliferative diabetic retinopathy (DR) (n = 67) compared with healthy control subjects (n = 20). Thirty-four patients had no DR, 15 had mild DR, and 18 had moderate to severe DR. Retinal oxygen saturation in arteries and veins was measured using the oxygen module of a retinal vessel analyzer. Total retinal blood flow (TRBF) was measured using a custombuilt Doppler optical coherence tomography system. Retinal oxygen extraction was calculated from retinal oxygen saturation and TRBF. Arteriovenous difference in oxygen saturation was highest in healthy subjects (34.9 +/- 7.5%), followed by patients with no DR (32.5 +/- 6.3%) and moderate to severe DR (30.3 +/- 6.5%). The lowest values were found in patients with mild DR (27.3 +/- 8.0%, P = 0.010 vs. healthy subjects). TRBF tended to be higher in patients with no DR (40.1 +/- 9.2 lL/min) and mild DR (41.8 +/- 15.0 lL/min) than in healthy subjects (37.2 +/- 5.7 lL/min) and patients with moderate to severe DR ( 34.6 +/- 10.4 lL/min). Retinal oxygen extraction was the highest in healthy subjects (2.24 +/- 0.57 lL O-2/min), followed by patients with no DR (2.14 +/- 0.6 lLO(2)/min), mild DR (1.90 +/- 0.77 lL O-2/min), and moderate to severe DR (1.78 +/- 0.57 lL O-2/min, P = 0.040 vs. healthy subjects). These results indicate that retinal oxygen metabolism is altered in patients with type 2 diabetes. Furthermore, retinal oxygen extraction decreases with increasing severity of DR.