Retinitis Pigmentosa (RP) is the term collectivly used to describe a group of inherited eye disorders affecting the retina. For most people with RP, the first symptoms are difficulty seeing at night and loss of peripheral (side) vision. These symptoms result from a loss of the rod photoreceptor cells within the retina. Peripheral vision loss is progressive, leading to "tunnel vision" in most affected individuals. In some less common types of RP, central vision is first lost due to a loss of cone photorecptor cells within the retina. Individuals with cone cell loss typically also experience light sensitivity and poor color vision.
The severity of RP is highly variable: some children are diagnosed with RP before the age of 5, while others remain asymptomatic until their 60's.
Retinitis pigmentosa is a genetic disorder, but it can be inherited in different ways. The different "types" of RP result from different underlying genes. Over 100 separate genes are believed to cause RP. RP can be inherited as a dominant, recessive, or X-linked trait. Genetic testing can sometimes clarify the inheritance pattern for a particular individual or family.
Retinitis pigmentosa affects 1 in 4,000 people, making it a rare disease. Compared with other genetic disorders, though, RP is common--almost as common as cystic fibrosis (CF) in the Caucasian population or sickle cell anemia in the African American population. RP affects people of all ethnic backgrounds.
Helful LinksFoundation for Fighting Blindness
Gene Clinics (Excellent medical genetics information web site. Choose Gene Reviews, then retinitis pigmentosa.)