Choroideremia

What is choroideremia?

Choroideremia (pronounced “kuh-roy-der-ee-me-ah”) is a rare inherited disease that affects your eyes. It causes vision to get worse and then leads to blindness. Severe disease mostly affects men and people assigned male at birth (AMAB).

Choroideremia is similar in some ways to retinitis pigmentosa, another condition that causes your retina to degrade. In fact, the two diseases have similar symptoms and sometimes have similar test results. Getting a genetic test is the best way to tell the difference between the two diseases.

In your eye, your retina has photoreceptor cells that capture light and turn it into electrical signals. Those signals travel along your optic nerve to your brain where they’re turned into images. The choroid is a layer between your retina and sclera, which is the white protective covering of your eye.

The choroid has blood vessels that feed your retina. Damage to your choroidal blood vessels leads to damage to your retina and peripheral sight.

How common is choroideremia?

Choroideremia affects an estimated 1 in 50,000 to 1 in 100,000 people.

What are the signs and symptoms of choroideremia?

The signs and symptoms of choroideremia include:

• Difficulty seeing at night (night blindness). This often happens before the age of 10.
• Difficulty with peripheral (side) vision.
• Lack of visual acuity (sharpness).
• Loss of the ability to see colors well.
• Increasing vision loss from the side that can progress to blindness.

What causes choroideremia?

Choroideremia is an X-linked genetic disorder. The gene that causes choroideremia is located on your X chromosome. Women and people assigned female at birth (AFAB) have two X chromosomes, while men and people AMAB have one.

Because there’s only one X chromosome with the faulty gene related to choroideremia, women and people AFAB don’t normally have the same vision problems that men and people AMAB with the faulty gene on their X chromosome have. Women and people AFAB may develop night blindness or glare issues later in life, but rarely go blind from choroideremia.

But men and people AMAB have one X chromosome and one Y chromosome. They’re more prone to developing X-linked genetic disorders. Affected males pass on their X chromosome to children AFAB, who become carriers. Those children AFAB have a 1 in 2 chance (50%) of passing the faulty X chromosome to their children AFAB.

How is choroideremia diagnosed?

It’s important to get regular eye exams, but an eye care provider will certainly examine your eyes if you report symptoms. They’ll likely do these tests, as well as others:

• Electroretinogram: This test measures your retina’s response to light. A provider will place electroencephalogram disks on your face, eyes, head and scalp, and then place very thin wires over the front of your eye, directly above your bottom eyelid. The technician will flash bright lights in front of your eyes to measure your retina’s activity.
• Optical coherence tomography (OCT): This type of test is a noninvasive imaging method that uses reflected light to create pictures of the back of your eye.
• Fluorescein angiography: Angiography is a test that uses dye injected through your veins to show the blood vessels in your eye.
• Genetic testing: A DNA test, or genetic testing, can identify mutations in your genes. A lab can use samples from your blood, hair, skin, tissue or amniotic fluid. Genetic testing can tell the difference between choroideremia and retinitis pigmentosa.

How is choroideremia treated?

Providers can’t cure choroideremia. But you may receive treatment for other issues. For instance, as vision gets worse, you may find that you can use some strategies for coping with low vision. Coping tips range from devices like magnifiers to counseling for mental health and genetics.

What can I expect if I have choroideremia?

Generally, people with choroideremia can expect their peripheral vision to get worse over time, leaving only central vision. Eventually, the condition may progress to blindness. There isn’t a cure.

How do I take care of myself?

You can take care of yourself by following guidelines for a healthy life, including:

• Eating a healthy diet that includes green leafy vegetables, other vegetables, fruit and lean protein. Avoid excess salt, sugar and unhealthy fats.
• Getting enough physical activity.
• Quitting smoking if you smoke.
• Having regular eye exams.
• Getting enough sleep.

When should I see my healthcare provider?

You should see a healthcare provider whenever you have a change in vision. If any of the changes are sudden or painful, consider getting emergency care.

See a provider if you find you’re having difficulties with your daily activities.

Ask for information on being eligible for gene therapy trials, too.

What is the difference between choroideremia and gyrate atrophy of the choroid and retina?

Both diseases are genetic conditions. They may have similar signs and symptoms. However, there are also differences.

• You inherit gyrate atrophy of the choroid and retina in a different way from choroideremia. The pattern for inheriting gyrate atrophy is autosomal recessive, which means that both parents pass the gene to their child. The pattern for inheriting choroideremia is X-linked. A parent with two X chromosomes passes the gene to their child.
• The mutated gene in choroideremia is different from the mutated gene in gyrate atrophy.

A note from Cleveland Clinic

Choroideremia is an incurable condition that causes vision to get worse and then can lead to blindness. Having a condition that doesn’t have a cure can result in many emotions. But having a strong relationship with a healthcare team can help. Research is going on right now into developing treatments and cures for choroideremia and other genetic diseases. And there are resources that currently exist to help you with your needs. Accepting help can make your life easier.