The Cornea and Corneal Disease

The eyes work in detailed ways with many complex structures, and these structures need protection. This protection is called the cornea – a clear, thin outer layer that protects the eye from dirt, bacteria and other germs or contaminants.

Several problems with the eyes occur in the cornea. Many of these are genetic or develop outside of our control, but you can help prevent conditions of the cornea by observing good hygiene habits, especially if you wear contacts or glasses.

How does the cornea function? What are diseases that affect it and their treatments? Here’s a look.

Structure of the Cornea

There are three layers in a healthy cornea:

Epithelium: The outermost layer, which blocks unwanted materials. It also absorbs oxygen and nutrients created by tears.
Stroma: The middle layer, formed mostly by water and proteins.
Endothelium: The back of the stroma. Pulls out extra liquid to prevent blurred vision.

While the cornea acts as a barrier, it also filters sunlight and plays a big role in vision. It helps the eye focus and process light, and damage to the cornea can cause a number of problems with vision.

Corneal Diseases

There are a large number of conditions that might affect the cornea. They include:

Keratitis: Inflammation usually caused by bacteria or fungi, often after an injury or trauma to the eye. Pain and vision problems are common, and a discharge from the eye often occurs.
Herpes: Called ocular herpes when it’s in the eye. A recurring viral infection that causes sores on the eyes. Can be treated with antiviral medication.
Shingles: Also called herpes zoster, this is a recurrence of chickenpox in people who have already had it. It can infect all parts of the body, including the eye.
Map-dot-fingerprint dystrophy: One of several kinds of dystrophy, this causes strange folds or patterns on the outside of the cornea. Most common in children or adults between 40 and 70, and can cause pain, light sensitivity and strange feelings in the eye.
Keratoconus: Another form of dystrophy where the cornea changes its shape. Can be caused by genetics, eye trauma or a number of eye diseases. Usually treated with glasses or contacts, or a cornea transplant in some severe cases
Fuch’s dystrophy: A condition where the endothelium deteriorates over time. Usually occurs in older people, and progresses over a number of years. More common in women than men. Can be treated with ointments or transplantation in other cases.
Lattice dystrophy: Overlapping lines of protein in the stroma that cause vision problems. Also treated with ointments or eye drops for mild cases, or transplantation in serious cases.
Other dystrophy: There are several other kinds of corneal dystrophy that are much more rare.

Symptoms and Treatments

Symptoms vary based on each condition, but in most cases, the cornea will heal itself. Many of the symptoms you experience are actually from the healing process:

Tears or blurred vision
Pain in the eyes
Redness
Light sensitivity, often extreme
Scarring of the cornea

Most treatments are basic, and involve things like eye drops and ointments. Some people may need glasses or contacts permanently as a result of corneal diseases, and in severe cases, a corneal transplant is needed.

Preventing corneal diseases is about keeping the area around the eyes clean and preventing major injuries to the eyes. Take special care to keep bacteria and fungi away – don’t share makeup or contact solutions, and wash your hands before and after handling your contacts or glasses. If you have questions, speak to your ophthalmologist.