Retinitis pigmentosa (RP) describes a group of related diseases that tend to run in families and cause a slow but progressive loss of vision. RP affects the rods and cones of the retina, the light-sensitive nerve layer at the back of the eye, and results in a decline in vision in both eyes. RP usually affects both eyes equally, with severity ranging from no visual problems in some families to blindness at an early age in others. RP gets its name from the fact that one of the symptoms is a clumping of the retinal pigment that can be seen during an eye exam.
The earliest symptom of retinitis pigmentosa, usually noticed in childhood, is night blindness or difficulty with night vision. People with normal vision adjust to the dark quickly, but people with night blindness adjust very slowly or not at all. A loss of side vision, known as “tunnel vision,” is also common as RP progresses. Unfortunately, the combination of night blindness and the loss of peripheral vision can be severe and can lead to legal blindness in many people.
While there is a pattern of inheritance for RP, 40% of RP patients have no known previous family history. Learning more about RP in your family can help you and your ophthalmologist predict how RP will affect you.
Usher’s syndrome, a condition that causes both deafness and blindness, is a form of RP. The incidence of Usher’s syndrome is difficult to determine, but surveys of patients suggest up to 10% of RP patients are deaf. The incidence of Usher’s syndrome is three cases per 100,000. It is the most frequent cause of combined deafness and blindness in adults.
Considerable research is being done to find the hereditary cause of RP. As hereditary defects are discovered, it may be possible to develop treatments to prevent progression of the disease. While developments are on the horizon, particularly in the area of genetic research, there is currently no cure for retinitis pigmentosa.
Nutritional supplements may be of benefit in RP. It has been reported that vitamin A can slow the progression of RP. Large doses of vitamin A are harmful to the body, and supplements of vitamin E alone may make RP worse. Vitamin E is not harmful if taken along with vitamin A or in the presence of a normal diet. Your ophthalmologist can advise you about the risks and benefits of vitamin A and about how much you can safely take.
Despite visual impairment, people with RP can maintain active and rewarding lives through the wide variety of rehabilitative services that are available today. Until there is a cure, periodic examinations by your ophthalmologist will keep you informed of legitimate scientific discoveries as they develop.