Cornea and External Disease (Allergies, Pterygium, Lid Margin Disease, etc.)
Approximately 22 million people in the United States suffer from seasonal itchy, swollen, red eyes. Airborne allergens, such as house dust, animal dander, and mold, constantly bombard the eyes and can cause ocular allergies at any time. But when spring rolls around and the plant pollen starts flying, it seems as if almost everyone starts crying.
Keratoconus is an uncommon condition in which the dome-shaped cornea (the clear front window of the eye) becomes thin and develops a cone-like bulge. As the condition progresses, the shape of the cornea is altered, distorting your vision. Usually, keratoconus affects both eyes, although symptoms and progression in each eye may differ.
A pterygium is a mass of fleshy tissue that grows over the cornea (the clear front window of the eye). It may remain small or may grow large enough to interfere with vision. A pterygium most commonly occurs on the inner corner of the eye, but it can appear on the outer corner as well.