Retinitis pigmentosa (RP) is a group of inherited eye diseases that often leads to severe visual problems. The retina is a layer of light-sensitive tissue that lines the back of the eye. It converts visual images that we see into nerve impulses that it sends to the brain. Some types of RP are associated with other inherited conditions. This disorder is named for the irregular clumps of black pigment that usually occur in the retina with this disease.
Normal Anatomy of the Eye
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Many types of RP are caused by a genetic mutation. Some cases occur sporadically.
Vision loss occurs when light-sensitive cells in the retina gradually break down. There are two types of cells in the retina:
- Cones—These cells are found mostly in the center of the retina. Cones are needed for central vision and to see colors.
- Rods—Located mostly away from the center, rods respond to dim light. They provide night and peripheral vision.
In most forms of retinitis pigmentosa, the rods die. Vision, thus, becomes impaired at night. The ability to see things off to the side while looking ahead also decreases.
In some forms of RP, the cones are lost. In those cases, central and color vision suffers. Vision loss usually progresses over a period of many years.
Last reviewedDecember 2014by Michael Woods, MD
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