Retinitis Pigmentosa

What is retinitis pigmentosa?

The retina is a layer at the back of your eye that converts light into electrical signals, allowing your brain to see the world around you. Retinitis pigmentosa (RP) is the term for a group of inherited eye diseases (IRDs) that affect your retina. RP is the most common type of inherited eye disease. Examples of other inherited retinal diseases include:

• Cone-rod dystrophy.
• Congenital stationary night blindness.
• Leber's congenital amaurosis.
• Usher syndrome.

Your eye is often compared to a non-digital camera. The front of your eye contains a lens (just like a lens of a camera). This lens focuses images on the inside of the back of your eye, the retina (just like film in a camera). If the camera film is damaged, it doesn’t matter how much you focus the camera, the picture is not going to be perfect.

Similarly, a diseased retina will affect your vision even if the front of your eye functions well. This includes people with corrective eyeglasses or contact lenses.

Your retina consists of special nerve cells that react to light. These cells include photoreceptor cells such as rods and cones and retinal pigment epithelium cells. For proper sight, it’s essential that these cells work together harmoniously. The genetic mutations that cause RP and other IRDs prevent these cells from functioning properly.

Since RP is a group of disorders, the visual changes vary among different people. Most people with RP have low vision, and some people go blind. The vision changes usually start in childhood. But, sometimes these changes occur so slowly that you don’t realize it’s happening. Some people have faster vision loss. In some types of RP, vision loss stops at a certain point.

Retinitis pigmentosa generally affects both eyes.

If you are diagnosed with RP or IRD, it’s important to obtain genetic testing that can sometimes determine the exact mutation causing the disease. Genetic testing is done with a specifically trained genetic counselor who can help with the ordering and interpretation of the test. Identifying the mutation is important because it can provide insight into how the disease may progress and how other family members may be affected. It also might qualify you to receive gene therapy or participate in a gene therapy clinical trial.

How common is retinitis pigmentosa?

There are an estimated 1 in 3,500 to 1 in 4,000 people in Europe and the U.S. who have retinitis pigmentosa. Globally, RP affects about 1 in 3,000 to 1 in 4,000 people, or about two million people total. In the U.S., this total is estimated at about 100,000 people.

What are the signs and symptoms of retinitis pigmentosa?

Early signs and symptoms of retinitis pigmentosa include:

• Problems with night vision.
• Problems seeing in dim light.
• Blind spots in peripheral (side) vision.

Later retinitis pigmentosa signs and symptoms may include:

• Having a sensation of twinkling or flashing light.
• Having tunnel vision (only central vision).
• Being sensitive to or uncomfortable in bright light (photophobia).
• Losing the ability to see color.
• Having very low vision.

What causes retinitis pigmentosa?

Retinitis pigmentosa, as other IRDs, is caused by changes in certain genes. These genes control the cells that make up your retina.

What tests will be done to diagnose retinitis pigmentosa?

It’s important to schedule and keep regular eye examinations. If your healthcare provider thinks you may have retinitis pigmentosa, they will use some or all of the following tests to make their diagnosis. They may also suggest genetic testing and/or counseling.

Dilated eye examination with visual field test

You may get your eyes examined by an optometrist or an ophthalmologist. Your provider will:

• Ask you to read letters off a chart on the wall.
• Ask you to follow objects with your eyes.
• Test the pressure in your eyes.
• Check your side vision (peripheral vision) with a visual field test.
• Check how your pupils react to light.
• Dilate your pupils with eye drops so they can see inside your eye.
• Take images of the retina.

Electroretinography (ERG) test

Electroretinography is a test that measures your retina’s response to light. It checks the function of different retinal cells. Your healthcare provider will flash lights in front of your eyes to measure your retina’s activity. Electroretinography is a type of ophthalmic electrophysiology test. These types of tests can check how your eyes and brain process what you’re seeing by measuring the electrical activity in your retinas, optic nerves, and visual pathways in your brain.

Optical coherence tomography scan

Optical coherence tomography (OCT) is a noninvasive test that can measure the thickness of your retina and analyze the retinal integrity. You are asked to look at a target as a special camera takes an image of the back of your eye.

Fundus autofluorescence test

This type of imaging test is noninvasive and can reveal information about the health of your retinas. It’s used for diagnosis, treatment and monitoring.

How is retinitis pigmentosa managed?

A lot of advances have been made in recent years in the field of RP and IRDs including the introduction of gene therapy.

The ways to manage RP include:

• Using low vision aids and assistive devices. There are a range of magnifiers and technology that can identify things or people that the wearer points to.
• Using sunglasses and other methods to avoid exposure to too much light. Light may make RP worse.
• Treating associated conditions, such as cystoid macular edema (CME), which may happen with RP. CME refers to collections of fluid in the middle of your retina.
• Treating cataracts, which happens when the lens of your eyes becomes cloudy, with surgery to remove them.

Are there other ways to treat retinitis pigmentosa?

The FDA has approved voretigene neparvovec-ryzl (Luxturna®), a gene therapy product to treat a specific type of retinitis pigmentosa. People with mutations in both copies of the RP65 gene may benefit from this type of therapy. This particular type of RP affects 1,000 to 2,000 people in the U.S.

There are ongoing clinical trials for gene therapy for the other types of RP and IRDs.

Some people with severe RP may be able to get an artificial retina, also called a retinal prosthesis.

What can I expect if I have retinitis pigmentosa?

RP doesn’t follow a certain schedule of progression, partly because there are so many different genes that can be involved. Different types of RP progress differently in different people. Appropriate genetic testing and counseling are important for anybody diagnosed with retinitis pigmentosa.

You may want to ask your provider about clinical trials, support groups or visual aids.

How can I prevent retinitis pigmentosa?

Because most forms of retinitis pigmentosa are inherited, you can’t prevent RP. You can, however, take steps to keep your eyes as healthy as possible by:

• Making and keeping regular appointments with your ophthalmologist.
• Wearing sunglasses and avoiding bright lights.
• Being as healthy as possible by eating right and exercising safely.

When should I see my healthcare provider?

As a general rule, see your eye care provider on a regular schedule. Always contact them if you have new or worsening symptoms, including:

• An increased loss of vision, either in terms of clarity or color.
• A new feeling of discomfort or pain.