How genetics is involved
November 21, 2022
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Your retina is the lining that covers the inner wall of the back of your eye. The cells in your retina are sensitive to light. They send signals to your brain so you can see. If you have inherited retinal dystrophy (IRD), a mutation in your genes changes the way your retina can work.

Although these disorders are considered rare, there are many different types. “‘Retinal dystrophy’ is a big term, potentially encompassing hundreds of different types of disorders and subcategories of disorders,” said Mandeep Singh, MD, PhD, retinal specialist and co-director of the Wilmer Eye Institute Genetic Eye Diseases (GEDi) Center at the Johns Hopkins Medicine in Baltimore.

Different types of IRDs appear at different ages and cause different types of symptoms. But all IRDs cause symptoms that affect your vision.

Some IRDs can even cause symptoms elsewhere in your body. These are known as syndromic retinal dystrophies. Most IRDs are degenerative, meaning they get worse over time.

What are some common types of IRDs?

retinitis pigmentosa. This is the most common group of IRD conditions. More than 1 in 3,000 people have them. The genetic mutation that causes retinitis pigmentosa occurs in the rod cells in your eyes.

“Rod cells are active when you need to see in low light, like at night or in a dim restaurant or movie theater,” says Singh. That’s why problems with your night vision are the most common symptom, he says. In addition, you may lose your peripheral (side), central, or color vision.

There are more than 100 genes that can cause retinitis pigmentosa, so doctors don’t use a single treatment for it. If your retina is swollen, you may need medicated eye drops. Surgery can help with cataracts that you can get. Specialists can help you with devices and aids to help you function with a visual impairment.

Vitamin A can help with some forms, although you may need genetic testing to confirm you have retinitis pigmentosa before trying this treatment, as it can make other forms of IRD worse.

Stargardt disease. Symptoms of Stargardt’s disease usually appear in childhood. This condition affects a specific part of your retina called the macula. Your macula helps you have sharp central vision. A mutation in a gene called ABCA4 causes a build-up of fat around your macula, affecting your vision.

“Typically at Stargardt, you have trouble reading fine print, face recognition, and fine vision,” says Singh. You may also have:

  • Gray, black, or blurred patches in the center of your field of vision
  • sensitivity to light
  • Problems adjusting between light and dark places
  • color blindness

To diagnose you, your doctor may test your color vision, take photos of your retina to look for yellowish spots on your retina, or do a test called electroretinography to see how well your eyes respond to light.

There aren’t any treatments for Stargardt’s disease yet, but you can slow your vision loss by taking steps like avoiding vitamin A and passive smoking.

“Sunglasses and avoiding very bright lights are also helpful, since bright light environments can often be difficult to adjust to,” says Jose S. Pulido, MD, MPH, Larry Donoso Chair of Translational Ophthalmology at Wills Eye Hospital in Philadelphia.

cone dystrophy. You get cone dystrophy when cells called cones in your retina start to lose their function. Cone cells are located in your macula and help you see color and deal with bright light.

In addition to having trouble seeing colors, you can also experience eye pain when exposed to a lot of light. “People with cone dystrophy tend to turn away and have visual discomfort in bright light,” says Singh.

You may have cone dystrophy symptoms when you are born, or you may develop them over time. Cone dystrophy is an X-linked mutation, meaning it’s passed through the X-sex gene. Men get it much more often than women.

There is no cure for cone dystrophy, but you can relieve your symptoms with tinted glasses or dark-colored sunglasses in bright environments. You can also use magnifying devices to better see fine print or other detailed objects.

Juvenile retinoschisis. You get this condition because of a genetic mutation that affects the structure of your retina. “Juvenile retinoschisis impairs your retinal cells’ ability to stick together,” says Singh. “The retina expands and accumulates fluid, and that damages vision.”

Only men get it, and symptoms typically appear before the age of 10. Retinoschisis means “the splitting of the retina into two layers”. It can cause bleeding in your eye and retinal detachment (pulling away). You may have trouble reading and recognizing faces, lose your peripheral vision, and just have trouble seeing in general.

Your doctor can diagnose the problem by looking for tears or cracks in the back of your eye. You can also use electroretinography to see how well your retina handles light. If you have bleeding in your eye, your doctor may use ultrasound to look for abnormalities.

You may need surgery if you bleed your eyes frequently or if your retina has become detached. You may also need to take certain precautions in your daily life to avoid further damage. “There should be long discussions about the possible harm from contact sports,” says Pulido.

Familial Exudative Vitreoretinopathy (FEVR). FEVR is a retinal vascular disease, meaning the blood vessels in your retina are affected. “FEVR impairs the retina’s ability to get enough oxygen, which means it doesn’t get enough nutrients to function and you have vision problems,” says Singh.

If you have it, you may have vision loss or blindness, retinal detachment, and eyes that don’t line up in the same direction because of a weakness in your eye muscles (strabismus). You may also have white in the black part of your eye (pupil). Some people with this condition have no vision problems at all.

Your doctor can treat FEVR with laser therapy. You may also need surgery to reattach your retina if it has pulled away from the back of your eye.

Leber Congenital Amaurosis (LCA). A congenital condition is one that you have at birth. Children born with LCA have rod and cone cells that don’t work as they should. Often this leads to severe vision loss or blindness.

You may also have squinting, eyes that move quickly and on their own, sensitivity to light, or cloudy lenses (cataracts). Some experts consider LCA to be a severe form of retinitis pigmentosa.

Mutations in more than two dozen different genes can cause LCA. Both parents must pass the mutation on to their child for the child to get the disease. As scientists identify which genes are responsible for LCA, they are also working to develop gene therapies to treat specific mutations.

“LCA has been in the headlines in recent years because the FDA approved a gene therapy drug for a specific subtype of LCA – LCA2 – that is caused by a mutation in a specific gene called RPE65,” says Singh.

Therapy can help improve vision in people with LCA2. Only 6% of people with LCA have this type.

Genetic testing for IRDs

Although your doctor can diagnose many IRDs with tools such as physical exams and eye tests, an important part of diagnosing and treating your IRD is determining which mutation you are dealing with.

“Genetic testing can be a pivotal moment in your clinical journey,” says Singh.

“Once we know the exact gene that causes your condition, we can tell you what we know about how it’s passed through families, and which companies and universities are developing treatments for those genes in clinical trials.” It helps you better understand your illness and make decisions about your family and personal health.”


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