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.

Retinal oxygen saturation in Chinese adolescents

PURPOSE

To study the retinal oxygen saturation in normal eyes of Chinese adolescents.

METHODS

Performing retinal oximetry with the Oxymap T1 Retinal Oximeter in healthy children and adolescents (aged 5-18 years old), we measured the arterial (SaO₂ ) and venular (SvO₂ ) oxygen saturation and the arteriovenous difference in oxygen saturation (Sa-vO₂ ).

RESULTS

The study included 122 individuals with a mean age of 13.0 ± 2.9 years (range: 5-18 years) and a mean refractive error of -3.25 ± 2.49 dioptres (range:-8.88 to +3.13 dioptres). Mean SaO₂ , SvO₂ and Sa-vO₂ was 85.5 ± 7.1%, 48.2 ± 5.5% and 37.3 ± 6.5%, respectively. Mean SaO₂ was significantly (p < 0.001) the lowest in the inferotemporal quadrant (79.1 ± 9.0%), followed by the superotemporal quadrant (83.4 ± 9.7%), the inferonasal quadrant (90.4 ± 10.6%) and the superonasal quadrant (93.4 ± 10.8%). In a similar manner, the values of the SvO₂ were the lowest (p < 0.001) in the inferotemporal quadrant (42.1 ± 8.3%), followed by the superotemporal quadrant (47.8 ± 7.2%), the inferonasal quadrant (52.3 ± 8.4%) and the superonasal quadrant (55.1 ± 7.6%). Arteriovenous difference in oxygen saturation (Sa-vO₂ ) did not differ significantly (all p > 0.05) between the fundus quadrants. In multiple linear regression analysis, SaO₂ increased (regression coefficient r²  = 0.28) with older age (standardized regression coefficient β: 0.23; p = 0.01) and more myopic refractive error (β: -0.39; p < 0.001). Higher SvO₂ was significantly correlated with more myopic refractive error (β: -0.46; p < 0.001; r²  = 0.20), while Sa-vO₂ increased significantly only with older age in the multivariate analysis (β: 0.26; p = 0.01; r²  = 0.07).

CONCLUSIONS

Our study provides normative data for Chinese children and adolescents who showed lower values than adults for SaO₂ and SvO₂ . SaO₂ increased with older age and higher myopic refractive error, SvO₂ increased with higher myopic refractive error, and Sa-vO₂ increased with older age.