Early diagnosis and evolution of dominant retinitis pigmentosa.

A 5-month-old girl with retinitis pigmentosa was the healthy offspring of a family with progressive autosomal dominant retinitis pigmentosa. Serial evaluation by both electroretinograph and ophthalmoscopy over a four-year period confirmed the diagnosis and indicated that as early as 5 months of age, electroretinographic abnormalities were present in the patient. These consisted of a reduction in the dark-adapted b-wave amplitude, prominent X-wave, and no suppression of the second b-wave response to paired light stimuli at 75 msec. Progressive reduction in the scotopic electroretinography amplitude has occurred over the ensuing four years, although light-adapted (cone) function still appears normal. Clinical evidence of retinitis pigmentosa became apparent only late in the patient's third year when fine peripheral pigment clumping and vessel attentuation could be seen.