Frequency of central visual impairment in retinitis pigmentosa.

To the Editor .—Retinitis pigmentosa (primary pigmentary degeneration of the retina) is a group of clinically similar-appearing, but genetically varied, disorders principally affecting the rods and characterized by night blindness and peripheral visual field impairment. Central vision is said to be spared until late in the course of the disease, when cones may also become affected. Recently acquired data indicate that such optimism regarding the preservation of central visual acuity is probably unwarranted. One hundred and sixty-seven consecutive patients with retinitis pigmentosa were studied. The criterion visual acuity was 20/50 or less in either or both eyes. Twenty-five patients with decreased central vision due to cataracts, chorioretinitis, myopic retinal degeneration, glaucoma, and other similar nonretinitis pigmentosa-related disorders were eliminated from the study, as were seven patients with apparently unilateral disease. Forty-eight percent of the sample group had central vision of 20/50 or less; 52% had vision better than 20/50. Results