Tapeto-retinal degeneration in four Norwegian counties, I. Diagnostic evaluation of 89 probands.

An attempt was made to trace all cases of tapeto-retinal degeneration in Norway. Four counties (fylker) were selected for personal examination of probands with a diagnosis of unspecified tapeto-retinal degeneration, retinitis pigmentosa, or Usher syndrome. The examinations led to the rejection of the diagnosis of tapeto-retinal degeneration in three persons, and in another four persons a diagnosis of choroidal dystrophy was made. The specific type diagnosis was adjusted in 26 additional persons. The results indicate that in Norway the diagnosis of retinitis pigmentosa may be made too frequently. Patients with Usher syndrome, choroideremia or cone-rod dystrophy are most often given the diagnosis of retinitis pigmentosa. Retinitis pigmentosa of pericentral type is in general not specified, and the diagnosis of tapeto-retinal degeneration without specified type diagnosis and retinitis pigmentosa are sometimes intermingled.