Usher's syndrome. Ophthalmic and neuro-otologic findings suggesting genetic heterogeneity.

The conditions of 70 patients with Usher's syndrome were studied by ophthalmic and neuro-otologic examinations. Two distinct clinical and presumed genetic types were discernible on the basis of differences in hearing impairment, vestibular sensitivity, and, to a lesser extent, deterioration in retinal photoreceptor function. Distinguishing these two types has relevance for both diagnosis and genetic counseling of patients with Usher's syndrome.