What conditions can damage the cornea?

What conditions can damage the cornea?

Keratitis

This is an inflammation of the cornea that sometimes occurs with infection after bacteria or fungi enter the cornea. These microorganisms can enter the eye after deep injury, causing infection, inflammation and ulceration of the cornea. Though uncommon, this type of infection can also arise after injury from wearing contact lenses.

Symptoms of keratitis include:

• Severe pain.
• Reduced visual clarity.
• Corneal discharge.
• Light sensitivity.

Treatment usually includes antibiotic or antifungal eye drops.

Ocular herpes (herpes of the eye)

This is a viral infection of the eye that may reoccur (return). The main cause of ocular herpes is the herpes simplex virus I (HSV I). This is the same virus that causes cold sores, but ocular herpes can also result from the sexually transmitted herpes simplex II virus (HSV II) that causes genital herpes.

Ocular herpes produces sores on the surface of the cornea that can lead to scarring and reduced vision. The inflammation can spread deeper into the cornea and eye.

There is no cure for ocular herpes, but it can often be controlled with the use of antiviral drugs.

Herpes zoster (shingles)

Shingles is a recurrence (return) of the chickenpox virus in people who have already had the disease. After the bout of chickenpox, this virus usually remains inactive within the nerves of the body. It can later travel down these nerves, infecting specific parts of the body, like the eye. Herpes zoster can cause blisters or lesions on the cornea, fever and pain from affected nerve fibers.

Corneal lesions usually heal by themselves, but antiviral treatment may shorten the course of disease. Some people develop chronic inflammation of the cornea after shingles requiring use of long-term eye drops, or less commonly, corneal surgery.

Shingles can occur in anyone exposed to the chickenpox virus, but there's an increased risk in older adults (especially those over age 65) and people with a weakened immune system.

See your ophthalmologist if you have any symptoms of shingles near or in the eye.

Corneal dystrophies

There are more than 20 corneal dystrophies, diseases that cause structural problems with the cornea. Some of the most common are:

Keratoconus

Keratoconus is a progressive disease in which the cornea thins and changes shape. Keratoconus changes the curvature of the cornea, creating either mild or severe distortion, called irregular astigmatism and usually nearsightedness. Keratoconus may also cause swelling and scarring of the cornea and vision loss.

Causes of keratoconus include:

• Genetics (a person can inherit a tendency to get the condition from a parent).
• Eye trauma (for example, from rubbing your eyes or long-term use of hard contacts).
• Eye diseases, such as retinitis pigmentosa, retinopathy of prematurity; allergic conditions such as hay fever, eczema and vernal keratoconjunctivitis.
• Other diseases, like Down syndrome, osteogenesis imperfecta, Addison's disease, Leber's congenital amaurosis and Ehlers-Danlos syndrome.

At first, the condition is correctable with glasses or soft contact lenses. But, as the disease progresses, you may need to wear rigid gas permeable contact lenses.

A corneal transplantation may also be necessary. During this procedure, the damaged cornea is replaced with a donated cornea. This operation is successful in about nine out of 10 people with advanced keratoconus. Even after a transplant, you most likely will need glasses or contact lenses to see clearly.

Corneal crosslinking is a newer treatment for keratoconus which uses a special type of ultraviolet light to activate riboflavin eye drops placed on the cornea. This can stabilize the cornea and slow the progression of disease. Your doctor may recommend an evaluation for this treatment if you are a candidate for this therapy.

Map-dot-fingerprint dystrophy

Map-dot-fingerprint dystrophy is a corneal condition which causes abnormal folds and reduplications of the epithelium, the outermost layer of the cornea. The effects of these changes are patterns in the cornea that resemble maps, dots and small fingerprints.

Map-dot-fingerprint dystrophy usually affects adults between the ages of 40 and 70, or children as a result of heredity. It is usually painless and causes no vision loss. In some cases, however, epithelial erosions may occur. Epithelial erosions are spontaneous corneal abrasions that occur, exposing the nerves lining the cornea and causing severe pain. The cornea's normal curvature may be altered, causing astigmatism and nearsightedness.

As the cornea is altered, vision may be blurry and accompanied by:

• Moderate to severe pain.
• Increased sensitivity to light.
• Excessive tearing.
• A feeling that something is in your eye.

Most patients with this condition require no treatment. If erosions are occurring, they may be managed with topical lubricating ointments, special contact lenses or a minor surgical procedure to debride (remove) the abnormal surface tissue.

Fuch's dystrophy