Your cornea – the clear, protective outer layer of the eye – not only protects your eye from dirt and germs, but also plays a key role in your vision. As light enters the eye, it is focused or refracted by the shape of the cornea. If your cornea sustains damage through disease, infection or injury, the resulting scar tissue can interfere with your vision by blocking or distorting light as it enters your eye.

There are several different conditions including infections, degenerations and other disorders that affect the cornea. These include:

Astigmatism: Caused by an irregularly shaped cornea, astigmatism is a refractive error in which the eye has trouble focusing light. Astigmatism is the most common form of corneal problem. Treatment typically involves the use of glasses or contacts.

 Corneal Abrasion: Caused by trauma to the eye, a corneal abrasion refers to a scratch on the outer layer of the eye. It is the second most common form of corneal distress. Treatment traditionally involves patching of the eye, though newer bandage contact lenses are beginning to see more use. These allow people to stay functional during the healing process.

Keratits: This form of corneal disease is an inflammation of the cornea that occurs with viral, bacteria or fungal infection. Symptoms of keratitis include severe eye pain, reduced visual clarity, and discharge.

Ocular Herpes (Herpes of the Eye): Similar to cold sores on the lip, this reoccurring viral infection produces sores on the surface of the cornea that, in time, 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): This is actually a recurrence of the chickenpox virus, since most of us have already had the disease. Symptoms of Herpes Zoster include blisters or lesions on the cornea, fever, and pain from inflamed nerve fibers.

Corneal Dystrophies

There are over 20 of these diseases that cause structural problems with the cornea. The most common forms include:

Keratoconus: This is a progressive disease in which the cornea thins and even changes shape, creating either mild or severe distortion (astigmatism) and nearsightedness (myopia).

Map-Dot-Fingerprint Dystrophy: As the basement membrane of the epithelium of the cornea grows irregularly, abnormalities resembling maps, dots and fingerprints form in the cornea. While this form of corneal disease is mostly painless and causes no vision loss, epithelial erosion may occur, exposing the nerves lining the cornea and causing severe eye pain.

Fuchs’ Dystrophy: Seemingly happening for no apparent reason – although you may have a genetic predisposition to the disease – Fuch’s Dystrophy involves the gradual deterioration of endothelial cells. As these cells thin, they can no longer remove water from the corneal stroma. This causes the stroma to swell and distort vision.

Lattice Dystrophy: This disease is characterized by the presence of abnormal protein fibers throughout the stroma. This can result in the clouding of the cornea and reduced vision and in rare cases, epithelial erosion.

Symptoms of Corneal Disease

 The cornea has the ability to quickly repair itself after most injuries or diseases. However, more serious situations may result in a much more prolonged healing process. If this is the case, the following symptoms should serve as an immediate indicator of a deeper medical issue:

• Eye pain
• Blurred/blurry vision
• Tearing
• Redness
• Extreme sensitivity to light
• Corneal scarring

If you feel you may be experiencing any of these symptoms, schedule an appointment with your eye doctor immediately. Any sudden change in your vision is a serious medical condition that requires prompt medical attention from your optometrist or ophthalmologist.

Although corneal disease resulting from hereditary factors cannot be prevented, infectious corneal disease caused from bacteria and viruses can be avoided. You should never share eye makeup, contact solution, lens cases, and eye drops with anyone as this may increase the risk of infection.

However, if you do contract some form of corneal disease, vision can be preserved through early detection and treatment. This is just another reason why regular eye exams are so important.

If you have any questions about what you have just read, please contact board certified ophthalmologist Samuel Boles and the eye care specialists at Anne Arundel Eye Center by calling 410-224-2010.

Led by Dr. Boles, the Anne Arundel Eye Center offers complete ophthalmic exams as well as diagnostic pre and post-surgical eye care. Specializing in glaucoma and cataracts, Dr. Boles has helped restore and preserve thousands of patients’ vision.

For more eye care advice and information, please take a look at our previous blog posts.

Sources:

Your Cornea: Conditions, Symptoms and Treatments