Retinitis Pigmentosa is an inherited disease affecting the retina.It is caused by a breakdown in the function of the rods, which control night vision, the cones, or in some cases a failure in another part of the retina.The retina is so complex that damage can occur in a number of ways.Retinitis Pigmentosa is not a single disorder but a group of related disorders leading to visual loss.
Different types of Retinitis Pigmentosa can have different symptoms.The most common type of early symptom is difficulty seeing at night or in dark rooms.It can also lead to tunnel vision where side vision is lost.In another type of Retinitis Pigmentosa the side vision is retained but there is a loss of central vision leading to difficulty with reading and close tasks.
Each person has a different rate of sight loss. For some, the loss of sight is slow and there may be only a small loss over perhaps ten years or more. Others have periods of rapid loss, often with years in between with no apparent decline. Some will have been aware of poor vision since their childhood or teens. If the retinitis pigmentosa runs in the family, the pattern could be the same within that family. Usually the loss is gradual enabling people time to adjust.
Retinitis pigmentosa can eventually lead to blindness but usually most people retain a small amount of vision although they are termed "blind" for legal purposes.