Relationships Between Serum Antioxidant and Oxidant Statuses and Visual Function in Retinitis Pigmentosa

PURPOSE. To investigate the serum changes of antioxidant/oxidant markers and the relationship between these factors and visual function in patients with retinitis pigmentosa (RP). METHODS. Fifty-two RP patients <40 years old and 25 controls were included. Serum samples were analyzed for superoxide dismutase 3 (SOD3) activity, glutathione peroxidase (GPx), potential antioxidant (PAO), and hexanoyl-lysine (HEL). The relationships between these markers and visual parameters, including best-corrected visual acuity (BCVA), mean deviation (MD), and average retinal sensitivity of 4 or 12 central points on static perimetry tests (Humphrey Field Analyzer, the central 10-2 program) were examined in the RP patients. RESULTS. Although there was no significant difference in the serum SOD3 activity between RP patients and controls, serum SOD3 activity in the severe degeneration group with macular involvement (16.3 +/- 11.3 U/mL) was significantly lower compared with those in the mild degeneration group (those with midperipheral scotomas; 28.5 +/- 16.6 U/mL, P = 0.0459). SOD3 was significantly related to visual acuity (r = -0.3701, P = -0.0069) and the average retinal sensitivity of four central points (r = 0.3463, P = 0.0137) in RP patients. The linear trends of these two parameters across SOD3 levels were also significant (P = 0.0264 and 0.0172, respectively). There was no consistent correlation between other serum antioxidant/oxidant markers and visual parameters. CONCLUSIONS. Lower serum SOD3 activity was associated with the severe retinal degeneration in RP patients. Our results suggest that serum SOD3 activity may be related to disease severity in RP.