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 an inherited retinal dystrophy (IRD), a mutation in your genes changes the way your retina is able to work.
While these disorders are considered to be rare, there are many different kinds. “‘Retinal dystrophy’ is a big term that encompasses possibly hundreds of different types of conditions and subcategories of conditions," says Mandeep Singh, MD, PhD, retinal specialist and co-director of the Wilmer Eye Institute Genetic Eye Diseases (GEDi) Center at Johns Hopkins Medicine in Baltimore.
Different types of IRDs show up at different ages and cause different types of symptoms. But all IRDs cause symptoms that affect your sight.
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 conditions. More than 1 in 3,000 people have them. The genetic mutation that causes retinitis pigmentosa happens in the rod cells of your eyes.
“Rod cells are active when you need vision in low light, like at nighttime or in a dim restaurant or movie theater,” Singh says. That’s why the most common symptom involves trouble with your night vision, he says. In addition, you might lose your peripheral (side), central, or color vision.
There are more than 100 genes that can cause retinitis pigmentosa, so doctors don’t use one single treatment for it. If your retinas are swollen, you may need medicated eye drops. Surgery can help with cataracts you may get. Specialists can help you with devices and tools to help you function with low vision.
Vitamin A may help with some forms, although you may need genetic testing to confirm you have retinitis pigmentosa before you try this treatment, since it can make other forms of IRD worse.
Stargardt disease. Symptoms of Stargardt disease usually show up in childhood. This condition affects a specific part of your retina called the macula. Your macula is what helps you have sharp central vision. A mutation in a gene called ABCA4 causes fatty buildup around your macula, affecting how well you see.
“Typically with Stargardt, you’ll have trouble reading fine print, facial recognition, and fine vision,” Singh says. You may also have:
- Gray, black, or hazy spots in the center of your vision
- Sensitivity to light
- Trouble adjusting between light and dark places
- Color blindness
To diagnose you, your doctor may test your color vision, take photos of your retina to check for yellowish flecks on your retina, or do a test called an electroretinography to see how well your eyes react to light.
There aren’t any treatments for Stargardt disease yet, but you can slow down your vision loss if you take steps like avoiding vitamin A and secondhand smoke.
“Sunglasses and avoidance of very bright lights is also helpful since it’s common to have a difficult time adjusting to bright-light environments,” 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 in your macula, and help you see color and handle bright light.
In addition to having trouble seeing color, you may also feel eye pain when you’re in lots of light. “People with cone dystrophy tend to turn away and be visually uncomfortable in bright light settings,” Singh says.
You may have symptoms of cone dystrophy when you’re born, or you may develop them over time. Cone dystrophy is an X-linked mutation, which means it’s passed down through the X sex gene. Men are much more likely to get it than women.
There’s no cure for cone dystrophy, but you can ease your symptoms with tinted lenses or dark sunglasses in bright environments. You can also use magnifying devices to help you 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 affects your retinal cells’ ability to stick to each other,” Singh says. “The retina expands and accumulates fluid, and that damages vision.”
Only males get it, and typically symptoms show up before you’re 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 at the back of your eye for tears or rips. They can also use electroretinography to see how well your retina does with light. If you have a hemorrhage in your eye, your doctor may use ultrasound to check for abnormalities.
You may need surgery if you have frequent eye bleeding or if your retina has detached. You also may need to take certain precautions in your daily life to prevent further damage. “There should be long discussions about the possible damage from 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 ability of the retina to get enough oxygen, which means it doesn't get enough nutrients for its function, and you have vision issues,” Singh says.
When you have it, you might have vision loss or blindness, retinal detachment, and eyes that don’t line up in the same direction because of weakness in your eye muscles (strabismus). You might also have whiteness in the black part of your eye (pupil). Some people with the condition don’t have 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 you have at birth. Children born with LCA have rod and cone cells that don’t work the way they should. Often this causes severe vision loss or blindness.
You may also have crossed eyes, eyes that move rapidly 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 your parents have to pass the mutation to their child in order for the child to get 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 headlines in recent years because the FDA approved a gene therapy medicine for one specific subtype of LCA -- LCA2 -- caused by a mutation in a specific gene called RPE65,” Singh says.
The therapy can help improve eyesight 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 vision tests, a key part of diagnosing and treating your IRD is finding out which mutation you’re dealing with.
“Once we know the precise gene that's causing 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 disease and make choices with respect to your family and their personal health.”