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. When you have hereditary retinal dystrophy (IRD), a mutation in your genes changes the way your retina can work.
Although these conditions are considered rare, there are many different types. “’Retinal dystrophy’ is a broad term that potentially encompasses hundreds of different types of conditions and subcategories of conditions,” says Mandeep Singh, MD, PhD, retina specialist and co-director of the Wilmer Eye Institute Genetic Eye Diseases (GEDi) Center at 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 in other places in your body. These are called 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 disorders. More than 1 in 3,000 people have them. The genetic mutation that causes retinitis pigmentosa occurs in the rod cells of your eyes.
“Rod cells are active when you need vision in low light, such as at night or in a dim restaurant or movie theater,” says Singh. That’s why the most common symptom involves problems with your night vision, 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 you may develop. Specialists can help you with devices and aids that will help you function better if you are visually impaired.
Vitamin A can help with some forms, although you may need genetic testing to confirm that you have retinitis pigmentosa before trying this treatment, as it can make other forms of IRD worse.
Stargardt disease. Symptoms of Stargardt disease usually appear in childhood. This condition affects a specific part of your retina called the macula. Your macula ensures that you have sharp central vision. A mutation in a gene called ABCA4 causes a build-up of fat around your macula, which affects how well you see.
“Normally with Stargardt you have difficulty reading small print, facial recognition and seeing clearly,” says Singh. You may also have:
- Gray, black, or blurry spots in the center of your vision
- Sensitivity to light
- Problems adjusting between light and dark places
- Color-blind
To diagnose you, your doctor may test your color vision, take pictures of your retina to check for yellowish spots on your retina, or perform a test called electroretinography to see how well your eyes respond to light .
There are no treatments yet for Stargardt’s disease, but you can slow your vision loss if you take steps such as avoiding vitamin A and secondhand smoke.
“Sunglasses and avoiding very bright light are also helpful, as it is often difficult to adapt to bright light environments,” says Jose S. Pulido, MD, MPH, Larry Donoso, Chairman of Translational Ophthalmology at the Wills Eye Hospital in Philadelphia.
Cone dystrophy. You get cone dystrophy when cells in your retina, called cones, begin to lose their function. Cone cells are located in your macula and help you see colors and deal with bright light.
In addition to having trouble seeing colors, you may also experience eye pain when you are in a lot of light. “People with cone dystrophy tend to turn away and feel visually uncomfortable in bright light,” says Singh.
You may have symptoms of cone dystrophy when you are born, or develop them over time. Cone dystrophy is an X-linked mutation, meaning it is passed on through the X sex gene. Men are much more likely to get it than women.
There is no cure for cone dystrophy, but you can relieve your symptoms with tinted lenses or dark sunglasses in bright environments. You can also use magnifying glasses to better see small 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 affects the ability of your retinal cells to stick together,” says Singh. “The retina expands and accumulates fluid, and that damages vision.”
Only men get it, and symptoms usually appear before you are ten. Retinoschisis means ‘splitting of the retina into two layers’. It can cause bleeding in your eyes and retinal detachment (pulling). 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 at the back of your eye for tears or cracks. They can also use electroretinography to see how well your retina handles light. If you have bleeding in your eye, your doctor may use an ultrasound to check for abnormalities.
You may need surgery if you have frequent eye bleeding or if your retina has become detached. You may also need to take certain precautions in your daily life to prevent further damage. “There should be long discussions about the potential harm of contact sports,” Pulido says.
Familial exudative vitreoretinopathy (FEVR). FEVR is a retinal vascular disease, which means it involves the blood vessels in your retina. “FEVR affects the retina’s ability to get enough oxygen, which means it doesn’t get enough nutrients for its function, and you end up with vision problems,” says Singh.
If you have it, you may experience vision loss or blindness, retinal detachment, and eyes not facing the same direction due to weakness in your eye muscles (strabismus). You may also have whiteness in the black part of your eye (pupil). Some people with the 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 a condition you have at birth. Children born with LCA have rod and cone cells that do not work as they should. This often causes severe vision loss or blindness.
You may also suffer from crossed eyes, eyes that move quickly and automatically, sensitivity to light or cloudy lenses (cataract). Some experts consider LCA to be a serious form of retinitis pigmentosa.
Mutations in more than twenty different genes can cause LCA. Both your parents must pass the mutation on to their child in order for the child to develop the condition. As scientists identify which genes are responsible for LCA, they are also working to develop gene therapies to help treat specific mutations.
“LCA has been in the news in recent years because the FDA approved a gene therapy drug for one specific subtype of LCA – LCA2 – caused by a mutation in a specific gene called RPE65,” says Singh.
The 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 like physical exams and vision tests, an important part of diagnosing and treating your IRD is figuring out which mutation you’re dealing with.
“Genetic testing can be a pivotal moment in your clinical journey,” says Singh.
“Once we know the precise gene that causes your condition, we can tell you what we know about it, how it passes through families, and which companies and universities are developing treatments for those genes in clinical trials. It helps you understand more about your illness and make choices about your family and their personal health.”