The corneal crosslinking is to treat the cornea with ultraviolet radiation to strengthen it and stop deformation happens in keratoconus. It is the main therapy to treat this disease that can prevent corneal transplantation. In keratoconus the cornea weakens and tends to shrink. The procedure is performed under topical anesthesia is applied to the cornea of riboflavin in the form of eye drops and focused beam of ultraviolet rays. The procedure takes about 30 minutes at the end of surgery, the patient must wear a soft contact lens. The results last from 3 to 10 years and the treatment can be repeated.