Cornea & External Disease

Corneal Dystrophies

A dystrophy is an inherited condition which usually develops in both eyes. Depending on the dystrophy, it can occur early in life or much later. Usually, dystrophies are slowly progressive; some decrease vision, some do not. Dystrophies can affect the surface of the cornea, the middle layers or the deepest parts. There are many types of dystrophies but the most common are:

Anterior Corneal Dystrophies

Symptoms

Basement Membrane Dystrophy (also know as map-dot dystrophy or geographic dystrophy) . This is the most common dystrophy of the cornea. It may be incidental (causing no problems with pain or blurred vision) or can give decreased vision or recurrent erosion syndrome.

The surface of the cornea has numerous fingerprint lines, or dots or whitish cysts. This can appear at any age but is more common over the age of 50. Usually it is bilateral. This condition may cause an irregularity to the surface of the cornea, giving blurred or ghost-like vision.

Treatment Options

A variety of treatment options include:

• Glasses to correct for astigmatism 
• Wearing a rigid contact lens, which gives a smooth surface to the eye and better vision 
• Surgical removal of the irregular surface (polishing the surface) and use of a soft contact lens for 5–6 days to heal the surface. The new smooth layer will give increased vision 
• Excimer lasers can be used to smooth the surface: PTK (phototherapeutic keratectomy-similar to PRK)

Middle Layer Dystrophies

Figure 1

Figure 2

Figure 3

Granular Dystrophy

Symptoms

This is dominantly inherited with “granular” looking spots (Fig 1) in the cornea giving a decrease in vision or recurrent erosion syndrome. The granules are made up of a substance called hyaline.

Treatment Options

When vision is significantly decreased, a corneal transplant is indicated.

Lattice Dystrophy

Symptoms

In this dominantly inherited condition, glass-like branching lines made of amyloid accumulate (Fig 2).

Treatment Options

One can have recurrent erosion syndrome or need a corneal graft to increase vision.

Macular Dystrophy

Symptoms

This is the least common of the middle layer dystrophies and recessively inherited (Fig 3). It can start at as young an age as 3–9 years. A mucopolysaccharide deposits in the cornea, appearing as large white spots that can grow together causing the whole cornea to become hazier.

Treatment Options

Treatment is similar to the above dystrophies.

Deep Layer Dystrophies

Figure 4

Figure 5

Figure 6

Fuchs Corneal Dystrophy (FCD)

Symptoms

Very common, FCD is dominantly inherited and more common in females, usually starting after 50 years of age (Fig 4). There is a dysfunction in the deepest layer of the cornea when the endothelial cells die off. These are non-reproducing cells that determine how much water gets into the cornea. This affected area looks like the surface of an orange (Fig 5). As more water comes into the cornea, it makes it hazier (edema) which decreases vision.

The early symptoms are blurred vision in the morning after the eyes have been closed all night. As time goes on, more swelling comes with worse vision. At advanced levels, one can even develop “blisters” on the surface, giving a foreign body sensation and pain (Fig 6).

Treatment Options

This condition can be treated in its early stages with salt drops or ointment that draws the water out of the cornea. Steroids can be used to help the “sick cells” work better. When severe, a full PKP or split thickness corneal transplant can be performed.

Additional Information

For more information, visit:

• EyeRounds.org
• Fuchs' Corneal Dystrophy
• RNIB
• OJRD