Keratoconus is a cone-shaped, non-inflammatory keratectasia, that concerns the central area of the cornea. It is a disease is unknown cause, although there is evidence for a genetic predisposition. It usually occurs during adolescence and slowly progresses until the age of 25 years. The disease affects both eyes, but the development time may be different for each.

The diagnosis is made clinically and confirmed by imaging methods such as corneal topography.

Mild cases can be treated with plain glasses, but most patients need special hard contact lenses to achieve the best possible vision. In some cases the hard lenses are not effective and patients may need surgery such as corneal transplantation or insertion of specific corneal rings.

A new, promising method that can halt the progression of the disease is the cross-linking of collagen with riboflavin. With this method a special riboflavin solution is topically applied to the cornea followed by about 30 minutes of ultraviolet radiation. This results in the creation of new bonds between collagen fibers contained in the cornea and an increase in endurance.