What Is It?
Retinitis pigmentosa is a disorder in which the cells in the eye that sense light break down (degenerate), leading to a slow loss of vision and sometimes blindness. The light-sensitive cells, called rods and cones, are in the retina, the back portion of the eye that sends visual information to the brain.
Approximately 100,000 people in the United States have retinitis pigmentosa, making it one of the leading causes of blindness. In people who have the disease, the first signs usually can be detected by about age 10, and the first symptoms usually show up in adolescence. The total amount of vision loss and how quickly the disease worsens vary from person to person.
No one knows exactly what causes retinitis pigmentosa. It is believed to be an inherited disorder, and research suggests that several different types of gene mutations (changes in genes) can cause this disease. In most cases, the disorder is linked to a recessive gene, a gene that must be inherited from both parents in order to cause the disease. But dominant genes and genes on the X chromosome also have been linked to retinitis pigmentosa. In these cases, only one parent has passed the disease gene. In some cases, a new mutation causes the disease to occur in a person who does not have a family history of the disease. The disorder also can show up as part of other syndromes, such as Bassen-Kornzweig disease or Kearns-Sayre syndrome.
The first symptom of retinitis pigmentosa is usually diminished night vision, so that it becomes more difficult to see in dimly lit or dark places. People with retinitis pigmentosa also slowly lose peripheral vision (side vision) and visual sharpness. Over time, the disorder leads to tunnel vision, in which the outer edges of vision are dark, leaving a shrinking circle of vision in the center. Eventually, people with retinitis pigmentosa can go blind, but most people with this disorder retain some vision even in old age.
An ophthalmologist (doctor who specializes in eye disorders) may do a number of tests to diagnose retinitis pigmentosa. Most commonly, the physician will use an instrument called an ophthalmoscope to look at the inside of the eye through the pupil. In a normal eye, the physician will see an orange or orange-red area called the fundus. In a person with retinitis pigmentosa, the orange area will have brown or black blotches. Visual-field tests can be done to measure a person's ability to see away from the center of vision (peripheral vision).
To confirm this diagnosis, an ophthalmologist may do a study called an electroretinogram (ERG). During this test, lights of different colors and intensities are flashed into your eye as you peer into a large reflective globe. A contact lens that contains an electrode is placed on your eye, and a wire transmits a record of your eye's retina activity. The ERG creates a paper tracing of electrical impulses that can be interpreted by an experienced physician. People with retinitis pigmentosa have lower electrical activity in the retina than is normal.
Retinitis pigmentosa is a genetic disorder, which means that people are born with the disorder already programmed into their cells. Doctors can see the first signs of retinitis pigmentosa in affected children as early as age 10. Symptoms typically begin in adolescence and slowly get worse over time. However, it is important to recognize that the severity of the disease varies from person to person. Many patients afflicted with this lead fairly normal lives. The disorder and visual loss last a lifetime.
Because retinitis pigmentosa is a genetic disorder, there is no way to prevent it from developing, and there is no proven way to prevent or delay the associated vision loss.
There is no known treatment for retinitis pigmentosa.
Some research suggests that taking high doses of vitamin A (15,000 IU/day) may slow degeneration a little in some people, but the results are not strong. Because there are potential toxic effects of too much vitamin A, and because the effect on the disease is weak, more research needs to be done before this therapy is accepted widely. If you have retinitis pigmentosa and want to try vitamin A therapy, talk with your physician first to learn about the safety and potential value of this treatment.
When To Call a Professional
See your health care professional if you notice any change in your vision, such as decreased ability to see at night or loss of peripheral vision.
Retinitis pigmentosa cannot be cured, and the visual loss is both progressive and permanent. Because the amount and speed of degeneration varies by individual, the extent of vision loss cannot be predicted.
American Academy of Ophthalmology
P.O. Box 7424
San Francisco, CA 94120-7424
National Eye Institute
2020 Vision Place
Bethesda, MD 20892-3655