The cornea is the transparent "window" covering the iris and the pupil of the eye. For vision to be clear, the cornea must be clear. Read below to learn about a few of the most common cornea conditions we diagnose.
Keratoconus means "cone-shaped cornea." An uncommon condition, keratoconus thins the cornea and changes its normally round contour to a cone-like bulge.
A healthy cornea properly focuses light rays entering the eye to give you clear vision. With keratoconus, the shape of the cornea is altered and vision is distorted, making activities like driving, using a computer, watching television, or reading more difficult.
Keratoconus usually affects both eyes, although the symptoms experienced with one eye may be different than those experience with the other eye. The symptoms of keratoconus typically begins during a person's late teens and early twenties and may include:
- Mild blurring of vision
- Slight distortion of vision
- Increased sensitivity to light
- Mild irritation
- Increased nearsightedness or astigmatism
- Frequent changes in eyeglass prescription
Keratoconus sometimes produces scar tissue that causes the cornea to lose its smooth texture and affects ability to see clearly.
The causes of keratoconus are unknown, but some researchers believe that genetics play a role. An estimated 10% of people with keratoconus have a family member with the condition.
Fuchs' dystrophy is a relatively common corneal dystrophy.
The cornea has three layers. The bulk of the cornea is called the stroma. The outer surface of the stroma is covered by the epithelium layer, which is several cells thick. A layer of endothelium lines the inner surface of the cornea.
The endothelium of the cornea is the primary area of pathology in Fuchs' corneal dystrophy. When the endothelium is unhealthy, the cells die, do not regenerate and they leave dots called "guttata" on the inside of the cornea. Guttata are often the first sign of Fuchs' dystrophy. Guttata cause glare and reduce quality of the vision.
In late stages of Fuchs' dystrophy, the corneal endothelial cells lose their ability to perform their primary duty, which is pumping fluid from the stroma. The stroma then accumulates fluid, causing corneal stromal edema, which makes the cornea become thicker. It also becomes more hazy, like a steamy window, and can cause a significant decrease in vision.