Autosomal dominantly inherited retinitis pigmentosa. Visual acuity loss by subtype.

Sixty-eight patients with autosomal dominant retinitis pigmentosa were divided into two distinct subtypes and studied for visual function using a life-table analysis. Type 1 patients (n = 23) had diffuse pigmentation, concentric visual field loss, and no recordable electroretinogram. Type 2 patients (n = 45) as a group had regionalized pigmentation, sectorial field loss, and some recordable electroretinogram. The cumulative probability of maintaining a visual acuity of 6/12 (20/40) or better over each decade of life decreased rapidly in eyes of type 1 patients; for type 2 eyes, this probability remained above 90% through the fifth decade of life. The presence of an atrophic-appearing foveal lesion was associated with a reduction in visual acuity to 6/15 (20/50) or worse in a majority of patients. Data from this study indicate that investigators should look for subtypes within the major genetic groupings of retinitis pigmentosa for more accurate assessment of a patient's potential for maintaining good central visual acuity.