Keratoconus is a disorder of the eye which results in progressive thinning of the cornea. This may result in blurry vision, double vision, nearsightedness, astigmatism, and light sensitivity. Usually both eyes are affected. In more severe cases a scarring or a circle may be seen within the cornea.

While the cause is unknown, it is believed to occur due to a combination of genetic, environmental, and hormonal factors. About 7% of those affected have a family history of the condition. Proposed environmental factors include rubbing the eyes and allergies. The underlying mechanism involves changes of the cornea to a cone shape. Diagnosis is by examination with a slit lamp.

Initially the condition can typically be corrected with glasses or soft contact lenses. As the condition worsens special contact lenses may be required. In most people the condition stabilizes after a few years without severe vision problems. In a small number of people scarring of the cornea occurs and a corneal transplantation is required.

Contact lenses are used to restore a better shape/focus. Most people with keratoconus have to rely on contact lenses to regain functional vision. Up until recently, it was the only way to manage the condition.

Corneal Collagen Cross-Linking (CXL) has now brought hope to keratoconus as this is the only surgical intervention that has shown that the progression of keratoconus can be halted.