Keratoconus is an eye condition in which the cornea, the clear front part of your eye, gradually becomes thinner and bulges outwards in a cone-like shape. In a healthy eye, the cornea is nicely round and dome-shaped, but in keratoconus it loses that regular shape. Because of this distortion, the light entering your eye is refracted irregularly, leading to blurred and distorted vision.
The condition usually begins between the ages of ten and twenty and often develops slowly over a period of ten to twenty years. Keratoconus can affect one or both eyes, and often one eye is more severely affected than the other. The cause is not fully understood, but there appears to be a hereditary component: the condition runs in families. Keratoconus is also associated with frequent eye-rubbing, allergies and certain connective tissue disorders.
In the early stages, you may notice very little, but as the cornea becomes more distorted, symptoms may develop such as increasing short-sightedness, irregular astigmatism, sensitivity to light, halos around light sources and difficulty seeing clearly, even with glasses. In advanced cases, the cornea may tear or develop scarring.
The diagnosis is made by an ophthalmologist or optometrist, often using corneal topography, a technique that maps the shape and thickness of the cornea. Keratoconus is a progressive condition, which means that in most cases it worsens gradually, although the course of the condition varies from person to person.