retinitis pigmentosa
pathology
group of hereditary eye (eye, human) diseases in which progressive degeneration of the retina leads to severe impairment of vision. In the usual course of disease, the light-sensitive structures called rods (rod)—which are the visual receptors used in dim light—are destroyed early on, causing night blindness in youth. Over time, further atrophy of the retina and changes in the layer of supporting cells known as the pigment epithelium occur. Commonly the field of vision becomes constricted until the affected person sees objects as if looking through a tunnel.In most cases, the course of disease is very slow, and progression to total blindness is uncommon. There are several hereditary patterns for retinitis pigmentosa, and multiple genetic (genetics, human) defects responsible for the various forms of disease have been isolated. Treatment is largely supportive and aimed at optimizing remaining vision. When retinitis pigmentosa is associated with congenital hearing loss, the condition is called Usher syndrome, which is the most common cause of combined blindness and deafness in the United States.
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