Keratoconus is a genetic disease of the cornea which affects its shape and its ability to focus light. It is considered a contraindication to LASIK laser vision correction surgery. Keratoconus is characterized by bio-mechanically weak, and often thin, corneal tissue. The cornea typically starts to deform and cause blurry vision starting in the mid to late teenage years and continues to deform until the mid to late 30’s. Symptoms can include blurry vision, double vision, ghosting, halos around lights, and glare. Often the distorted shape of the cornea makes it difficult to fit contact lenses. Corneal Cross Linking, or CXL, is a treatment which stiffens the cornea by applying a proprietary ultraviolet light to the tissue after treatment with riboflavin, a B vitamin. The riboflavin absorbs into the anterior portion of the cornea and “captures” the ultraviolet light when it is applied to the cornea, causing cross linking of the collagen fibers.  It is designed to add strength to the cornea and prevent progression of the deformation caused by keratoconus. Today, the FDA approved CXL using a proprietary version of riboflavin solution containing dextran called Photrexa Viscous and an electronic device, the KXL System, that applies the ultraviolet A light to the corneal surface. These products are made by Avedro. The FDA determined that the CXL system was safe and effective based on three 12-month U.S. clinical trials. In Europe, where CXL has been approved for quite some time, selected patients with keratoconus actually can have laser vision correction if they undergo CXL first, followed by PRK (flapless LASIK).