To study the retinal oxygen saturation in patients with retinitis pigmentosa (RP).Methods
Retinal Vessel Oximetry was performed with the oximetry tool of Retinal Vessel Analyzer (Imedos GmbH, Jena, Germany) on 12 eyes of 6 RP patients and on 24 eyes of 12 age-matched healthy controls (p=0.747, two-way ANOVA). RP patients were selected following a clinical and electrophysiological assessment. We evaluated the mean oxygen saturation of arteries (A-SO2), the mean oxygen saturation of veins (V-SO2), as well as the A-V-SO2 difference and compared them to the ERG values within both groups.Results
In controls, the mean A-SO2 and V-SO2 of the retina was 92.41% (SD, ±3.54) and at 53.99% (SD, ±2.95), respectively. In the RP group, the A-SO2 and the V-SO2 were increased to 100.13% (SD, ±7.24) and 66.96% (SD, ±5.67), respectively (p-values=0.000). The A-V-SO2 difference, known to be proportional to oxygen consumption, was reduced to 33.17% (SD, ±5.85) in RP when compared to the controls 38.39% (SD, ±3.00) in a linear regression model (p=0.001). The b-wave of the dark-adapted 3.0 ERG response compared to A-SO2, V-SO2, as well as A- V-SO2 difference within both groups, showed a linear correlation of: r=-0.571, r=-0.846, and r=0.531, respectively with the corresponding p-values <0.003. The b-wave of the light-adapted 3.0 ERG response compared to A-SO2, V-SO2 and A- V-SO2 difference, showed a linear correlation of r=-0.581, r=-0.807, and r=0.472, respectively, with the p-values <0.008.Conclusion
This is to our knowledge the first study data, which suggests the oxygen metabolism to be altered in cases with retinitis pigmentosa.