Abstract
Purpose: :
To measure the rates of visual acuity, visual field, and electroretinogram (ERG) loss in patients with X–linked retinitis pigmentosa due to retinitis pigmentosa GTPase regulator (RPGR) mutations and to determine if their rates of progression differ from those of patients with dominant retinitis pigmentosa due to rhodopsin (RHO) mutations.
Methods: :
We followed change in Snellen visual acuity, Goldmann visual field area (V4e white test light), and full–field 30 Hz (cone) ERG amplitude for an average of 11.4 years in 97 patients with RPGR mutations. After censoring data to eliminate "ceiling" and "floor" effects, we used PROC MIXED of SAS to determine longitudinal rates of change and to compare these rates with those for a previously studied cohort of 93 patients with dominant retinitis pigmentosa due to RHO mutations followed for an average of 11.3 years.
Results: :
Mean annual exponential rates of decline for the patients with RPGR mutations were 4.6% for visual acuity, 5.1% for visual field area, and 7.5% for ERG amplitude; each of these rates was significantly different from zero (p < 0.001). The rate of visual acuity loss was significantly faster for the RPGR patients than for the RHO patients (RHO: 2.1%; p = 0.009), while the rates for visual field area and ERG amplitude loss were comparable in the two groups (RHO: 3.5% and 8.8%, respectively).
Conclusions: :
Patients with X–linked retinitis pigmentosa due to RPGR mutations lose central vision, but not peripheral vision, more rapidly than patients with dominant retinitis pigmentosa due to RHO mutations.
Keywords: retinal degenerations: hereditary • clinical (human) or epidemiologic studies: natural history • degenerations/dystrophies