How cross-linking works
Keratoconus weakens the bonds between the collagen fibers of the corneal stroma, and the cornea bulges under normal eye pressure. Cross-linking restores strength chemically. Riboflavin absorbed into the cornea acts as a photosensitizer: when ultraviolet A light is applied at a set intensity and time, it generates reactive oxygen that forms new covalent bonds within and between the collagen fibers. The stiffened cornea resists further steepening. Studies report the effect is long lasting in most treated eyes.
The procedure
Numbing drops are placed and the eye is held open with a small speculum. In the standard, FDA approved epithelium-off technique, the surface epithelium is gently removed so the riboflavin can penetrate, and riboflavin drops are applied every few minutes for about 20 to 30 minutes until the stroma is saturated. Corneal thickness is checked; a thin cornea is swollen with hypotonic riboflavin to protect the inner layers. The ultraviolet light is then applied for a set period, with riboflavin continuing throughout. A bandage contact lens and antibiotic and anti-inflammatory drops finish the procedure. Total time is typically about an hour, and you go home with a driver.
Recovery
The first three to five days are sore, watery and light sensitive while the epithelium regrows, similar to PRK; prescribed pain relief and drops manage it, and most patients take the week off. The bandage lens is removed once the surface has healed. Vision is blurrier than before treatment for the first weeks, often for a month or two, then recovers to the pre-treatment level and in some patients improves slightly as the cornea flattens over the following year. Contact lenses are refitted once the cornea has stabilized, usually at one to three months. Tomography is repeated at six and twelve months and then annually to confirm the cornea has held.
Who should have it
Patients with keratoconus that is progressing on tomography, or, after discussion with the cornea specialist, young patients with clear disease in whom progression is likely, provided the cornea is thick enough to treat safely and is not scarred centrally. It is also used for ectasia after LASIK. Adults whose keratoconus has been stable for years usually do not need it. Cross-linking is not a vision correction procedure; it is about keeping the cornea you have.
Safety and results
Cross-linking has been performed since the early 2000s and has a strong safety record. Published studies report progression halted in most treated eyes, with a small proportion needing retreatment. Risks include infection while the surface is healing, temporary haze, and, rarely, delayed healing or a persistent surface defect, all of which are why the procedure is performed by a cornea specialist with close follow-up.
Is this right for your eyes?
Nothing on this page is a diagnosis. Whether this is the right choice for you is decided by a full examination at one of our 4 offices: Pasadena, Huntington Beach, Woodland Hills and Beverly Hills.
About this content: This page was written with the assistance of AI tools and reviewed for medical accuracy by Dr. Bavand Youssefzadeh, DO. It is general information, not medical advice, and does not replace an eye examination. Individual results vary. Read our medical disclaimer.
