RETINITIS PIGMENTOSA

hereditary eye disease in which progressive degeneration of the retinal pigments leads to impairment of vision and, ultimately, to blindness. In the course of the disease the light-sensitive structures called rodswhich are the visual receptors used in dim lightare destroyed early, causing night blindness in youth. Over time, further atrophy of the retina proper and of the layer of pigmented cells known as the pigment epithelium progressively constricts the field of vision until the affected person sees objects as if he were looking through a gun barrel. This stage is followed by complete blindness, usually by the age of 50. Deafness caused by a degeneration of the auditory nerve may accompany the visual loss. There are several hereditary patterns, but in most cases the disease is transmitted between generations as a recessive trait. Researchers have suggested that high doses of vitamin A may slow the loss of eyesight.