Retinal vessel oxygen saturation is affected in uveitis associated with Vogt-Koyanagi-Harada disease

Aims To discover whether retinal vessel oxygen metabolism is affected in uveitis associated with Vogt-Koyanagi-Harada (VKH) disease. Methods 41 patients with VKH disease (82 eyes) and 12 healthy subjects (24 eyes) matched in age and gender were prospectively evaluated. Retinal oxygen saturation and vessel calibre were measured with a non-invasive spectrophotometric retinal oximeter (Oxymap T1). Results In healthy controls, mean arteriolar oxygen saturation (%) was 93.8±5.9 and venular saturation was 60.1±5.8. In acute VKH uveitic phase associated with exudative retinal detachment (n=12), arteriolar and venular oxygen saturation values were 104.7±7.8 and 67.9±7.7, respectively, and both are significantly higher than the healthy group (p<0.001; p=0.001, respectively). In patients with VKH disease who recovered after immunosuppressive therapy and restored normal anatomy without 'sunset glow fundus' (n=13), oximetry values were 96.4±9.6 and 61.6±7.5, respectively, similar to healthy controls. In patients with 'sunset glow fundus' and chorioretinal atrophy (n=16), saturation levels were 88.6±7.8 and 50.0±13.1, respectively, significantly lower than healthy controls (p=0.02; p=0.003, respectively). These patients also had significantly smaller diameter of retinal arterioles and venules compared with controls (p=0.035; p=0.001, respectively). Conclusions Retinal oxygen metabolism is altered in uveitis associated with VKH disease. Oxygen saturation profile is abnormal in acute uveitic phase of the disease and returns to normal in those who recover with normal fundus appearance, but not in eyes that suffer permanent anatomical damage with 'sunset glow fundus' and chorioretinal atrophy. Retinal oximetry may be of value in evaluating vascular and metabolic aspects of posterior uveitis.