Purpose: This study was conducted to determine whether oxygen saturation and retinal blood vessel diameter are affected by retinitis pigmentosa (RP) at various ages.
Methods: Relative oxygen saturation was measured in retinal blood vessels in 68 RP patients and 136 normal subjects using the Oxymap T1 retinal oximeter. Subjects were divided into two age groups: Group A (20-40 years) and Group B (> 40 years). One randomly selected eye of each subject was used for statistical analysis. Student's t tests were used to analyze the mean saturation and diameter of retinal arterioles and venules and arteriovenous differences between RP and normal subjects in the two age groups. A Spearman test was used to analyze the correlation of mean saturation of retinal arterioles (AS) and arteriovenous differences (AVS) with visual acuity, disease duration, and electroretinogram (ERG) b-wave amplitude in patients with RP.
Results: AS was significantly higher in patients with RP (105.5 ± 9.4 %) than in normal subjects (94.5 ± 4.4 %, p = 0.000) in Group A, while in Group B, AS was significantly lower in RP patients (86.8 ± 10.3 %) than in healthy subjects (96.0 ± 4.8 %, p = 0.000). Vessel diameter was smaller in RP patients than in normal subjects. AS and AVS showed a negative correlation with disease duration and a tendency toward positive correlation with ERG b-wave in patients with RP.
Conclusions: The shifting characteristics of retinal vessel oxygen saturation suggest that the pathological mechanism of retinal oxygen metabolic disorder differs by age in patients with RP.
Keywords: Hypoxia; Oximetry; Oxygen saturation; Retina; Retinitis pigmentosa.