Any one of a large group of inherited disorders in which abnormalities of the photoreceptors (the rods and cones) in the retina lead to progressive visual loss. People with retinitis pigmentosa (RP) first experience defective adaptation to the dark (“night blindness”), then narrowing of the visual field (“tunnel vision”) and eventually loss of central vision. RP may be inherited in a number of different ways since more than 30 different genes are known to cause RP.
RP can occur alone or be part of a syndrome involving abnormalities outside the retina. For example, Usher Syndrome (includes both RP and deafness) is a relatively common form of RP.