Corneal Dystrophy

Corneal dystrophies are a group of rare genetic diseases that affect the eye's cornea. While they rarely result in total blindness, they can affect both eyes and impair visual acuity.

Being diagnosed with corneal dystrophy can sound intimidating. However, this is a rare eye condition that progresses slowly.

Layers of the Cornea

Corneal dystrophies can involve an accumulation of foreign material in one or more layers of the cornea. This can lead to blurry vision and decreased vision. 

It’s also highly treatable. This guide will clearly explain what's happening, how it might affect your vision, and outline proven treatment options to give you clarity and confidence.

Is Corneal Dystrophy Serious?

Corneal dystrophy simply describes a slow change in the clear front window of your eye (the cornea). Corneal dystrophy can be serious, but not all corneal dystrophies are severe. 

Some cases may cause mild symptoms or be detected incidentally during routine eye exams. Additionally, corneal dystrophy isn’t contagious, and it can stay mild or stable for years.

Lastly, it’s very rare. About 0.09% of people, roughly one in 1,100, have some form of corneal dystrophy.

Layers of the Cornea

Corneal dystrophies can involve an accumulation of foreign material in one or more layers of the cornea. This can lead to blurred vision and reduced vision.

The cornea consists of five layers:

• Epithelium. The outermost layer serves to protect the cornea. 
• Bowman’s membrane. A protective membrane beneath the epithelial layer. 
• Stroma. The thickest layer of the cornea. It’s composed of water, collagen fibers, and other connective tissue. It provides support and flexibility to the cornea. 
• Descemet’s membrane. A thin, strong, protective layer. 
• Endothelium. The innermost layer comprises cells that move excess water out of the cornea.

Who is At Risk of Corneal Dystrophy?

Some people may have a higher risk of developing corneal dystrophy than others. Risk factors include:

• Sex. Fuchs’ dystrophy will appear more often in females than in males. However, most corneal dystrophies impact males and females equally. 
• Genetics. Corneal dystrophies can run in the family, and specific genetic coding can determine which type of corneal dystrophy you’ll develop. 
• Age. Corneal dystrophies often occur in the 30s or 40s. As you age, the risk of developing an eye condition increases.

What Are the Different Types of Corneal Dystrophy?

While corneal dystrophy can be classified into more than 20 subtypes, there are three primary types of eye disease.

Anterior Corneal Dystrophy

If you have anterior corneal dystrophy, the outermost layers of the cornea are affected. These layers include the epithelium and Bowman’s membrane.

Examples of this type of corneal disease include:

• Epithelial basement membrane dystrophy (EBMD), also called anterior basement membrane dystrophy (ABMD) or map-dot-fingerprint dystrophy
• Meesmann dystrophy
• Reis-Bucklers dystrophy
• Thiel-Behnke dystrophy 

Stromal Corneal Dystrophy

While it primarily affects the stroma, this condition can expand to the posterior corneal layers, which involve Descemet’s membrane and the endothelium.

According to the International Committee for Classification of Corneal Dystrophies (IC3D), there are many different subsets of stromal corneal dystrophies, including:

• Lattice corneal dystrophy type 1 
• Lattice corneal dystrophy type 2
• Granular corneal dystrophy type 1  
• Granular corneal dystrophy type 2 (Avellino corneal dystrophy)
• Macular corneal dystrophy 
• Schnyder corneal dystrophy 
• Congenital stromal corneal dystrophy
• Fleck corneal dystrophy 

Posterior Corneal Dystrophy

Posterior corneal dystrophy involves abnormalities in the corneal endothelium and Descemet's membrane. This condition causes excess fluid (edema) and reduced visual acuity.

Examples of posterior corneal dystrophy include:

• Posterior polymorphous corneal dystrophy (PPCD)
• Congenital hereditary endothelial corneal dystrophy (CHED) 
• X-linked endothelial corneal dystrophy (XECD)
• Fuchs’ corneal dystrophy

Causes and Symptoms of Corneal Dystrophy

Corneal dystrophies occur due to deposits that progressively build up within a layer, or multiple layers, of the cornea. Fortunately, issues like inflammation, infection, or trauma don’t cause corneal dystrophy.

However, it can be genetic. Sometimes, genetic changes cause one of the cornea’s layers to develop cloudy spots, bumps, or accumulate deposits. The symptoms of corneal dystrophy include:

• Blurred vision 
• Halos around light
• Trouble seeing at night 
• Vision loss
• Clouding

These symptoms can overlap with other conditions like cataracts or glaucoma. Additionally, these symptoms may not always be present and could vary according to the corneal dystrophy type. 

What Are Some Complications of Corneal Dystrophy?

Aside from reduced visual acuity and other vision problems, corneal dystrophy can lead to corneal erosions. This happens when the layer of cells on the corneal epithelium (surface layer) breaks away from the underlying layer (Bowman’s membrane).

Recurrent corneal erosions can lead to:

• Mild to severe eye pain
• Sensitivity to light
• A sensation of something lodged in the eye (foreign body sensation)

Fortunately,  most corneal dystrophies rarely lead to total blindness, although advanced cases can cause severe vision loss or even blindness if untreated.

When to See a Doctor

You should see an eye doctor if you experience any symptoms of corneal dystrophy, especially if your symptoms appear suddenly.

Because symptoms of corneal dystrophy can overlap with those of other eye conditions, your eye doctor may refer you to a corneal specialist. They can perform a differential diagnosis to rule out other eye conditions.

Without treatment, corneal dystrophy can cause visual impairments and reduced vision. Fortunately, there are plenty of ways to treat the condition.

How is Corneal Dystrophy Diagnosed?

Doctors use precise, painless methods to pinpoint your type of corneal dystrophy. The most common approaches include:

• Slit-lamp exam. This microscope beams a thin, bright sheet of light into the eye and will help your doctor assess corneal swelling or irregular bumps (guttae).
• Corneal topography and OCT scans. Non-invasive imaging methods that map out your corneal shape and detect deeper changes.
• Corneal pachymetry. This test measures corneal thickness.
• Genetic testing. Occasionally recommended if there's a family history or unclear diagnosis, to identify specific gene mutations.
• Vision tests (visual acuity). Measures exactly how clearly you're seeing, helping assess the extent of any vision impairment.

How is Corneal Dystrophy Treated?

Treatment for corneal dystrophy depends on your type and the severity of your symptoms. If you don’t have any symptoms, an eye care specialist may monitor you for any possible progression.

If you have symptoms, you may receive one or more of the following treatments:

• Non-surgical options. Your doctor may prescribe antibiotics, lubricating eye drops, ointments, or a special protective contact lens to address corneal erosion and relieve other symptoms.
• Laser treatment. Laser treatments, like phototherapeutic keratectomy (PTK), may be recommended if medications and other therapies fail to improve your symptoms.
• Corneal transplant surgery. If your condition causes severe vision problems your doctor may recommend a full or partial corneal transplant (keratoplasty). This removes damaged corneal tissue and replaces it.

How to Manage Corneal Dystrophy

Beyond treatment, there are several strategies you can adopt daily to maintain your comfort and visual clarity. Here's how you can support your eyes at home and work:

• Manage bright light and glare at home.
• Adjust screen brightness for digital devices.
• Wear sunglasses outdoors.
• Exercise regularly and have healthier dietary habits.
• Wear special soft contact lenses to cushion your cornea.