The cornea is the eye’s clear and protective outer layer. Along with the sclera (the white portion of the eye), it serves as a barrier against dirt, germs, and other things that can cause damage. It is a fact that cornea can also filter out some of the sun's ultraviolet light.
It also plays a key role in vision. As light enters in the eye, it gets refracted, or bent, by the cornea’s curved edge. This helps determining how well an eye can focus on objects close-up and far away.
If the cornea is damaged by disease, infection, or an injury, the resulting scars can affect the vision. They might block or distort light as it enters the eye.
The term corneal disease refers to many conditions that affect this part of the eye. These include infections, tissue breakdown, and other disorders.
The cornea generally heals itself after most minor injuries or infections. But during the healing process, the following symptoms may be noticed:
These symptoms are also faced in other eye problems, so they may signal a more serious issue which requires special treatment.
There are several types of diseases which can cause problems with the cornea’s structure:
Keratoconus: Cornea gets thin and changes its shape in this disease. It usually starts with blurred vision during teenage years and worsens during early adulthood. Changes to the curvature of cornea can create mild to severe distortion, called astigmatism, and usually nearsightedness. The disease can also lead to swelling, scars on your cornea, and loss of vision. Your night vision can get so bad that you can’t drive after dark.
Corneal Dystrophies: The structural problems are caused within your cornea. Some of the most common are:
Map-dot-fingerprint dystrophy. The back layer of your epithelium gets affected, which separates it from the stroma. It grows in an irregular (thick in some places, thin in others) way. These irregularities in cornea look like maps, dots, and small fingerprints.
It usually affects adults over 40. It’s usually painless, usually doesn’t affect vision, and gets better without treatment. But sometimes the epithelial layer can get worn out and the nerves that line your cornea gets exposed. This causes severe pain, especially when you wake up in the morning. It may also change cornea's normal curve and cause astigmatism, nearsightedness, or farsightedness.
As the cornea changes, your vision may get blurred. You may also notice:
Treatments include an eye patch, a soft contact lens "bandage," eyedrops, ointments, "tacking it down," or removing the loose layer.
Fuchs' dystrophy: This is a genetic condition causing a slow breakdown of endothelial cells and the swelling of the cornea. This makes it hard to remove water from your stroma. Your eye swells and your vision gets worsened. Haze and small blisters might appear on the surface. Symptoms of the disease might appear in your 30s or 40s, but it takes about 20 years for it to affect your vision. Women get affected more often than men.
An early sign: You wake up with blurred vision that slowly gets clear during the day. As the disease worsens, swelling becomes more consistent and vision stays blurred.
Strict hygiene guidelines need to be followed if you wear contact lenses. Improper use of lens is the main reason for developing corneal diseases. It will lower down your chances of corneal infections related to their use. Don’t sleep with contact lenses in the eyes, even if they’re FDA approved for it.
You can’t prevent diseases that you inherit from your parents (like dystrophies). But you can hang onto your vision if you find and treat them on time.