What Is It?
Retinitis pigmentosa is a disorder in which the rods and cones of the retina (the light receptors of the eye) slowly degenerate. People with retinitis pigmentosa experience progressive loss of night vision, peripheral vision and visual sharpness in both eyes. 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, total blindness can result, but most people with retinitis pigmentosa retain some vision even in old age.
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 progresses 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. Other symptoms include:
- Loss of visual acuity
- Loss of peripheral vision
- Tunnel vision
- Inability to differentiate colors
An ophthalmologist may perform 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 an eye unaffected by retinitis pigmentosa, the physician will see an orange or orange-red area called the fundus. In a person with retinitis pigmentosa, brown or black blotches will be present in the orange area. Visual-field tests 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. 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 provider 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.
Diseases and Conditions Center
All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.