Keratoconus is an uncommon condition in which the cornea becomes thin and the center protrudes. Keratoconus literally means a cone shaped cornea. This abnormal shape can cause serious distortion of vision.

The cause of keratoconus remains unknown. Although keratoconus is not generally considered an inherited disorder, the chance of a blood relative having the disorder is thought to be as high as one in 10. Although vigorous eye rubbing is not the cause of keratoconus, it can contribute to the disease process. Therefore, patients with the disorder are advised to avoid rubbing their eyes.

Blurring and distortion of vision are the earliest symptoms of keratoconus. Symptoms usually first appear in the late teens or twenties. The disease will often progress slowly for 10 to 20 years, then stabilize for awhile. In the early stages, the vision may be only slightly affected, causing glare, light sensitivity and irritation. This disease may affect one eye or both. As the disease progresses and the cornea steepens and scars, vision may become severely distorted.

A sudden decrease in vision may occur if the cornea swells (corneal hydrops). The cornea swells when the elastic part of the cornea develops a tiny crack, created by the strain of the cornea's protruded cone-like shape. The swelling may persist for weeks or months as the crack heals and is gradually replaced by scar tissue.

Mild cases are successfully treated with glasses or specially designed contact lenses. When vision is no longer satisfactory with glasses or contact lenses, surgery, a corneal transplant is often recommended.