The cornea is the clear window in the front of your eye. It transmits light to the interior of your eye, so you can see clearly.
Corneal disease is an umbrella term that describes any disorder that impacts your cornea. There are a number of types of corneal disease. The three principal types of corneal disease are keratoconus, bullous keratopathy and Fuchs’ dystrophy. In addition, some individuals suffer from pterygium, another disorder affecting the cornea.
Keratoconus. With keratoconus, the center of the cornea becomes increasingly thin and weak, leading to a cone-shaped abnormality in the cornea. This type of corneal disease can progress gradually, quickly or intermittently. Usually, keratoconus occurs in both eyes, but it is possible for it to develop in one eye only. As the cornea becomes increasingly cone shaped, wearing contact lenses may become difficult. Also, as the cornea steepens, those with the disease may experience increasingly blurred vision.
Bullous keratopathy. This type of corneal disease is characterized by a damaged endothelium, the thin layer of cells lining the inside of the cornea. A healthy endothelium pumps fluid out of the cornea. For individuals with bullous keratopathy, the damaged endothelium is not able to pump fluid out of the cornea properly. The result is that the cornea swells permanently, causing poor eyesight.
Fuchs’ (endothelial) dystrophy. This type of corneal disease is also characterized by a damaged endothelium that cannot pump fluid out of the cornea. However, individuals with Fuchs’ dystrophy inherited a hereditary defect of the endothelium, which causes the cornea to swell and become cloudy, ultimately leading to declining vision.
In the early stages of both bullous keratopathy and Fuchs’ endothelial dystrophy, individuals may initially notice a glare when looking at lights at night or in bright sunlight. As these corneal diseases advance, you may notice blurry or foggy vision in the morning that clears up as the day progresses. In the advanced stages of both these corneal diseases, individuals may experience blurry vision later into the day that may ultimately not improve at all.
Pterygium. Pterygium is characterized by a benign growth on the conjunctiva, or the lining of the white section of the eye. The growth may eventually extend into the cornea and start to cover the iris, or the colored section of the eye. If left untreated, pterygium can ultimately impair vision. Because one possible cause of pterygium is frequent sun exposure (which surfers often experience), the corneal disease is often referred to as “surfer’s eye.” Symptoms of surfer’s eye include: a lesion on the eye; a dry, itchy eye; irritation; inflammation; redness; tearing; and a decline in vision, in its more advanced stages.