If the cornea of your eye becomes damaged through disease, infection, or injury, the resulting scars can interfere with vision by blocking or distorting light as it enters the eye.
The cornea is the clear, protective outer layer of the eye. Along with the sclera (white of the eye), it serves as a barrier against dirt, germs, and other particles that can harm the eye’s delicate components. The cornea is also capable of filtering out some amounts of the sun’s ultraviolet light.
The cornea also plays a key role in vision. As light enters the eye, it is refracted, or bent, by the outside shape of the cornea. The curvature of this outer layer helps determine how well your eye can focus on objects close-up and far away.
The term “corneal disease” refers to a variety of conditions that affect mainly the cornea. These include infections, degenerations, and many other disorders of the cornea that may arise mostly as a result of heredity.
With its ability for quick repair, the cornea usually heals after most minor injuries or infections. However, during the healing process a variety of symptoms may be experienced, including:
Although these symptoms may occur with many other types of eye problems, they may indicate a more serious problem or require special treatment. Therefore, if you experience any of these symptoms, seek care from an eye doctor.
Keratitis is an inflammation of the cornea that sometimes occurs with infection after viruses, bacteria, or fungi enter the cornea. These microorganisms can enter the eye after superficial or deep injuries, 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:
There are several types of corneal degenerations, diseases that can cause progressive structural problems with the cornea including. Keratoconus is a progressive disease in which the cornea thins and changes shape. Sometimes occurring as early as adolescence, this disease changes the curvature of the cornea, creating either mild or severe distortion, called astigmatism, and usually nearsightedness. Keratoconus may also result in swelling and scarring of the cornea and vision loss.
Factors associated with keratoconus include:
At first, keratoconus can be corrected with glasses or soft contact lenses. But, as the disease progresses, you may need to wear rigid gas permeable contact lenses. In approximately 10% to 15% of patients with keratoconus, a corneal transplant may also be necessary.
During a corneal transplant, 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 will still most likely need glasses or contact lenses to see clearly.