What it is
In keratoconus, the cornea gradually thins and bulges into a cone shape, causing blurred, distorted vision and frequently changing glasses power. Corneal collagen cross-linking (also called C3R or CXL) strengthens the cornea: riboflavin (vitamin B2) drops are applied and the cornea is exposed to a controlled dose of ultraviolet-A light, which creates new bonds — “cross-links” — between its collagen fibres.
Who it's for
People, often teenagers and young adults, with keratoconus that is getting worse, or with corneal weakening after refractive surgery (called ectasia). It works best at an early stage, before the cornea becomes too thin or scarred.
What to expect
The eye is numbed with drops. The thin surface layer of the cornea may be removed, riboflavin drops are applied for a period, and then the eye is exposed to UV light. A soft “bandage” contact lens is placed at the end. You go home the same day with someone to accompany you.
Recovery
Discomfort, watering and sensitivity to light are common for a few days while the surface heals, and vision may be blurry for some weeks. The aim is to stop the cornea getting worse rather than to improve vision, so glasses or special contact lenses may still be needed. Avoid rubbing your eyes.
Frequently asked questions
Will cross-linking improve my vision?
Its main aim is to stop keratoconus from getting worse. Some people see a small improvement, but most still need glasses or contact lenses.
Why should I avoid rubbing my eyes?
Frequent eye rubbing is linked to keratoconus getting worse. If your eyes itch, ask your doctor about treating the allergy instead.
Medically reviewed by Dr. Sweta Patro