Corneal Dystrophy

What is corneal dystrophy?

“Corneal dystrophy” is an umbrella term for over 20 different diseases that affect the cornea of your eye. Dystrophy-type corneal diseases can cause tissue changes or damage that disrupt how light passes through your corneas. If the disruptions are severe enough, they can cause changes or decreases in how well you see (vision loss).

Corneal dystrophy diseases are genetic. That means they happen because of DNA changes. Some of those changes are ones you can inherit from your biological parents. Others happen spontaneously. And some of these diseases happen for reasons that experts don’t fully understand yet.

Types of corneal dystrophy

The types of corneal dystrophies, based on the layer(s) in which they happen, are:

• Epithelial and subepithelial.
• Epithelial-stromal.
• Stromal.
• Endothelial.

Epithelial and subepithelial corneal dystrophies

• Epithelial basement membrane dystrophy.
• Epithelial recurrent erosion dystrophies (three subtypes).
• Gelatinous drop-like dystrophy.
• Lisch epithelial dystrophy.
• Meesmann dystrophy.
• Subepithelial mucinous dystrophy.

Most of these corneal dystrophies develop during early childhood, but there are two exceptions. The first is epithelial basement membrane dystrophy, which usually (but not always) happens in adulthood. The other is gelatinous drop-like corneal dystrophy, which can happen any time before age 20.

Epithelial-stromal dystrophies

• Granular corneal dystrophy (type 1 and type 2).
• Lattice corneal dystrophy (including multiple subtypes and variants).
• Reis-Bückler’s dystrophy.
• Thiel-Behnke dystrophy.

These conditions are all most likely to happen during childhood. One of them, Lattice corneal dystrophy type 1, can happen as late as age 20.

Stromal dystrophies

• Macular dystrophy.
• Schnyder crystalline dystrophy.
• Congenital hereditary stromal dystrophy.
• Fleck dystrophy.
• Posterior amorphous dystrophy.
• Pre-Descemet dystrophy.
• Central cloudy dystrophy of François.

The stromal dystrophies usually affect people during childhood. But two of these conditions can develop when you’re an adult. Schnyder corneal dystrophy can develop as late as age 30, and Pre-Descemet corneal dystrophy usually develops after age 30.

Endothelial corneal dystrophies

• Fuchs endothelial dystrophy.
• Posterior polymorphous dystrophy.
• Congenital hereditary endothelial dystrophy.
• X-linked endothelial dystrophy.

Of all the corneal dystrophies, Fuchs endothelial corneal dystrophy is the most common. It accounts for about 39% of all corneal transplants in the U.S.

What are the symptoms of corneal dystrophy?

The symptoms of corneal dystrophy depend partly on which specific type you have. Some people never have any symptoms at all. When symptoms do develop, they usually affect both eyes and get progressively worse over time.

Your corneas are kind of like commercially made glass that’s engineered to be clear, flawless and have a proper dome-like shape. But corneal dystrophies can change that. Many of these conditions involve new tissue formation or buildup in ways they shouldn’t or in locations where they don’t belong. Instead of flawless glass, it’s like looking through sections of flaw-riddled blown glass, which is harder to see through.

Those new formations or buildups can make it harder to see through the affected layers of your cornea. That makes symptoms like blurred vision or clouded vision common in people with corneal dystrophy.

The most common symptoms include:

• Visual acuity loss. This happens when the cornea’s surface distorts or wears away unevenly. This symptom means you have decreased eyesight clarity (low vision) despite refractive correction (like eyeglasses or contact lenses).
• Corneal haze. This makes your vision look hazy. It’s often a leftover effect of the corneal damage or changes.
• Foreign body sensation. This means you feel like you have something stuck in your eye, but you can’t find anything to cause it.
• Eye pain or eye irritation. These symptoms are more likely to happen when you’ve had your eyes closed for a longer time, like when you’re asleep.
• Light sensitivity (photophobia). This means bright light can feel overwhelming, uncomfortable or even painful.
• Watery eyes (epiphora). This can happen if your eyes feel dry, causing your tear system to produce too much tear fluid to try and compensate.
• Nystagmus. These are uncontrolled and rapid side-to-side or spiral-like eye movements.

What causes corneal dystrophy?

The many forms of corneal dystrophy all involve genetic factors. These can be “de novo” changes (meaning new changes you developed spontaneously) or changes you inherited from one or both of your biological parents.

Some of those inherited changes only need one copy of a gene from one biological parent. Other changes need two copies of the mutated gene, one from each biological parent. And there are still a few forms of corneal dystrophy where more research is necessary to determine the specific change(s) responsible.

What are the risk factors for this condition?

Most corneal dystrophies don’t affect people differently due to race or sex. One exception is Fuchs endothelial corneal dystrophy. It has a few specific risk factors:

• Race. It’s more likely to occur in people who are white.
• Age. It’s most likely to happen to people over 30.
• Sex. Women and people who are assigned female at birth (AFAB) are more likely to develop it.

What are the complications of corneal dystrophy?

The conditions that fall under corneal dystrophy affect how light passes through your cornea. That makes your cornea less clear and distorts light that travels through. That means corneal dystrophy can cause severe vision loss, but it won’t cause total blindness.

Still, severe vision loss can be a big issue. It can affect your ability to drive, read and do many other everyday activities.

How is corneal dystrophy diagnosed?

An eye care specialist, like an ophthalmologist or optometrist, can diagnose corneal dystrophy using a combination of tools and methods. The most important tool is an eye exam, especially specific parts of it like a slit lamp exam. The slit lamp exam involves using a special microscope to look inside your eyes. It lets providers see any changes or damage that happens with corneal dystrophy.

Other tests your eye care specialist may use include:

• Corneal topography. Corneal topography “maps” the surface of your cornea, showing any areas where the cornea surface is higher or lower than areas around it.
• Pachymetry. Pachymetry (pronounced “pack-IM-et-ree”) measures the thickness of your cornea, which can help identify issues with deeper layers of the cornea (endothelial dystrophies).
• Genetic testing. This usually involves testing a sample of your saliva or blood and looking for specific DNA changes. That can help confirm the specific type of corneal dystrophy.
• Optical coherence tomography (OCT). While commonly used for imaging your retinas, this test can also provide valuable scans of your corneas. It’s especially useful for planning certain types of corneal treatments.
• Corneal biopsy. An eye care specialist can take a tissue sample from your cornea for lab testing. A pathologist will analyze the sample and determine if you have corneal dystrophy and, if you do, which type it is. This test isn’t common for corneal dystrophy, but it can help with diagnosis.

Other tests may be possible, depending on your symptoms and other factors. Your eye care specialist can tell you more about any other tests they recommend.

How is corneal dystrophy treated?

There are many ways to treat corneal dystrophy. The treatment depends on the affected corneal layer and the severity of the condition.

Because the treatments can vary, your eye care specialist is the best source of information about your treatment options. They can explain the details of the procedures, including possible complications, side effects and other details.

Topical treatments

Topical treatments focus on treating symptoms and effects on the surface of your cornea. Examples include:

• Medicated eyedrops or ointments. These can treat symptoms like pain, foreign body sensation and dryness.
• Antibiotics. These can help prevent infections if your cornea has damage that makes it vulnerable to germs.
• Special contact lenses. Like standard contact lenses, these are wearable items that go on the surface of your cornea. The main difference is these help your corneas heal and prevent further damage.

Phototherapeutic keratectomy

Phototherapeutic keratectomy (PTK) uses a precisely tuned laser to remove areas of corneal tissue. Your eye care specialist can specifically target damaged areas for removal.

Cornea transplant

In cases where you have corneal changes or damage that are severe enough to affect your vision, a cornea transplant may be an option. These surgeries take corneal tissue from a deceased donor and use it to replace your corneal tissue. These can be partial or total transplants.

Can corneal dystrophy be prevented?

Corneal dystrophies are genetic. That means there’s no way to prevent them or reduce your risk of having them.

What can I expect if I have corneal dystrophy?

If you have corneal dystrophy, what you can expect can vary quite a bit. Most people usually get a diagnosis for one of the conditions by the time they reach age 20.

Corneal dystrophies are usually progressive. That means their effects develop gradually over time — usually over years or even decades. Some people go years without even knowing they have one of the conditions because they have no symptoms early on. And some people never develop any symptoms or issues.

Because what you can experience can vary so widely, it’s a good idea to ask your eye care specialist about what you should expect. They can tell you more about what’s most likely for you.

How long does corneal dystrophy last?

Corneal dystrophies are lifelong conditions. You have them when you’re born. Corneal transplants may “cure” these diseases, but it’s not a guarantee. Many people who receive a corneal transplant will eventually develop the disease in the transplanted cornea. If that happens, further treatment — up to and including another cornea transplant — may be necessary.

What’s the outlook for this condition?

Corneal dystrophies often cause at least some vision loss. But it’s rare for that vision loss to turn into total blindness (where you can’t even detect light).

If you have a cornea transplant, you'll face similar risks as people who undergo other types of transplants. You’ll likely need lifelong immune system suppression to keep your immune system from attacking the transplanted tissue. And rejection can still happen even with immune-suppressing treatments.

Because there are so many variables that can affect your outlook, your eye care specialist is the best person to ask about the prognosis for your case. They can tailor the information they provide so it’s more relevant to your specific situation.

How do I take care of myself if I have corneal dystrophy?

If you have corneal dystrophy, you should see your eye care specialist for regular follow-up visits as recommended. They can monitor your condition and track any tissue changes in your eyes or any symptoms you’re experiencing. They can also change and update your treatment plan so it stays as effective as possible for as long as possible.

If your specialist prescribes medications for your eyes, you should take them as prescribed. Medications can limit the symptoms of these conditions or slow down any tissue changes or damage.

Taking medications exactly as prescribed is critical if you receive any kind of corneal transplant. Doing so can make sure your body doesn’t reject the transplanted tissue, helping you avoid severe complications and even permanent vision loss.

When should I see my eye care specialist?

You should see your eye care specialist for regularly scheduled follow-up visits. You should also talk to them if you notice any symptom or vision changes, or if any treatments cause side effects or seem to be less effective. They can try to help you find solutions to issues that you may face.

What questions should I ask my eye care specialist?

You may want to ask your eye care specialist the following:

• What type of corneal dystrophy do I have?
• What treatment(s) do you recommend?
• Are there any symptoms that mean I should get emergency medical care?
• What’s the long-term outlook for my condition?
• Is there anything I can do to help improve my outlook?