Keratoconus is an uncommon condition in which the normally round, spherical shape of the cornea (the clear front "window" of the eye) thins and develops a cone-like bulge. The word keratoconus literally means "cone-shaped cornea."

Not much is known as to the cause of keratoconus. Some researchers believe that constant rubbing of the eyes can lead to the cone-shape to develop, while others believe that it is related to genetics since about 10% of the people with the disease also have a family member with keratoconus.

Symptoms usually begin in people in the late teens or early twenties, rarely developing after the age of 30. This disease usually affects both eyes. Common symptoms include blurry and/or distorted vision, light sensitivity, halos and/or glare around lights, and frequent changes in your glasses or contact prescriptions.

In it's early stages, keratoconus can often be treated with glasses or hard contact lenses. If the condition worsens and scars develop on the cornea, it may be necessary to perform a corneal transplant, though only about 20% of people with keratoconus require a corneal transplant.