Photoreceptor degeneration in a family of cats

Blindness developed at an early age in 2 generations of cats. Findings included abnormal pupillary responses to light, tapetal hyperreflectivity, retinal vascular attenuation, and virtually extinct electroretinograms. Histologic and ultrastructural abnormalities were found only in photoreceptors. There were poor inner and outer segment development and reduction in visual cell nuclei, with concomitant narrowing of the outer plexiform layer early in the postnatal period. Eventually, there was complete loss of the photoreceptor layer. The clinical and microscopic findings suggested this retinal disease may be a heritable rod-cone dysplasia.