Patient education: Retinitis pigmentosa (The Basics)

What is retinitis pigmentosa? — Retinitis pigmentosa (called "RP" here) is the medical term for a group of eye disorders that cause vision loss. RP mostly damages the back of the eye, called the "retina." This part of the eye contains the cells that react to light (figure 1).

RP is caused by one or more abnormal genes. It usually runs in families. There are many different types of RP. Some people with RP have other health problems, but some just have RP.

Over time, RP causes vision loss. It especially affects "peripheral" vision. Peripheral vision is how a person sees to the side. By age 40, most people with RP have very little peripheral vision. But they can often see straight ahead, see some details, and tell light from dark. Very few people with RP lose all their vision.

What are the symptoms of retinitis pigmentosa? — The symptoms of some forms of RP start in childhood. With other forms, people do not notice symptoms until later in life.

RP symptoms can include:

●Night blindness – This is the first symptom of RP. People with night blindness have more trouble seeing in dim light than they used to. The eyes might also take longer to adjust to dim light.

●Loss of peripheral vision

●Loss of sharp, clear vision – People with RP might not see small details or faraway objects as well as they used to.

Is there a test for retinitis pigmentosa? — Yes. During an eye exam, a doctor might find changes that make them suspect RP. This is more likely if RP runs in the family.

There are many tests for RP, but you might not need them all. The main tests include:

●Dark adaptometry – This test can tell doctors how much the RP has damaged the retina. After seeing a bright light, a person sits in a dark room for 30 minutes. Then the doctor shines dim lights to test how well the person sees.

●Electroretinography, also called "ERG" – This test measures electrical signals from the cells in the retina that react to light. During this test, a doctor gives medicine to make the eye numb. Then they puts a tiny wire under the lower eyelid. The wire picks up electrical signals from the retina. If RP has damaged the retina, the signals are not normal. An ERG test can find RP early. Sometimes, it can find RP before a person has any symptoms.

●Blood tests – These can show changes in the genes that usually cause RP. The changes can be a sign of RP.

Doctors can also measure peripheral vision and color vision. If you have RP, you will have regular eye checkups and tests.

How is retinitis pigmentosa treated? — Three rare forms of RP are treated with diet changes or vitamins. Your doctor will tell you if you have one of these forms.

Right now, there is no cure for the most common forms of RP. Eating foods with a lot of omega 3 fatty acid, such as fish, might help. But doctors do not recommend vitamins or diet changes for most people with RP.

Doctors can treat some of the problems that people with RP get. These problems and treatments include:

●Swelling of the macula (the center of the retina) – The swelling can make straight-ahead vision blurry. Medicines such as acetazolamide (brand names: Diamox, Sequels) or dorzolamide drops (sample brand name: Trusopt) can help with swelling.

●Cataracts – A cataract is a condition in which the lens of the eye becomes cloudy. The cloudy lens can make straight-ahead vision blurry. If cataracts get bad enough, an eye doctor can take out the cloudy lens and put a clear one in its place.

These treatments do not help peripheral vision or slow down RP.

Doctors are studying treatments that might help people with RP in the future. For example, in some cases they can replace damaged genes that cause RP. This treatment is called "gene therapy." Scientists are also studying how to put cells from a healthy retina into a damaged one, and how to create an artificial retina.

A clinical trial is a research study that tests a new treatment or medicine. If you are interested in trying new RP treatments, ask your doctor or nurse about clinical trials for RP.

More on this topic

Patient education: What are clinical trials? (The Basics)
Patient education: Cataracts (The Basics)