DefinitionRetinitis 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|
|Copyright © Nucleus Medical Media, Inc.|
CausesMany 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.
Risk FactorsRP is more common in males and in those with family members who have it.
SymptomsReduction of vision is usually first noted in childhood or early adulthood. The disease gradually worsens. After a number of years, vision loss may become severe.Symptoms vary, depending on the type of retinal cell that is affected. Both eyes often experience similar vision loss.It should be noted that RP is a slowly progressive disease over many years and that most people never become completely blind. In fact, even though many people with RP are considered “legally blind,” it is only because they have very constricted fields of vision (poor peripheral vision). Some still maintain excellent central visual acuity.In general, RP may cause:
- Night blindness (the most common symptom)
- Eyes take longer to adjust to dim lighting or are slow to make adjustment from bright sun to indoor lighting
- Trouble seeing in foggy or rainy weather
- Decreased peripheral vision/visual field narrows, often called "tunnel vision"
- Difficulty seeing colors, especially blue
- Visual loss, partial or complete, usually gradually progressive
- Clumsiness from lack of sight, especially in narrow spaces such as doorways
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