Photochemical corneal collagen cross‑linkage using riboflavin and ultraviolet A for keratoconus and keratectasia

Keratoconus is a degeneration of the structure of the cornea in which the corneal surface thins and begins to bulge into a cone shape. This causes refractive error, which is usually a myopic shift and is often associated with astigmatism, leading to visual impairment. It commonly affects children and young adults and may be progressive. Iatrogenic keratoconus (for example, as a result of laser-assisted in situ keratomileusis [LASIK] surgery) is called keratectasia.

In mild to moderate keratoconus, visual acuity can be corrected using spectacles, contact lenses and in some cases, intracorneal ring segment (ICRS) implantation. Keratectasia can be managed by using contact lenses or ICRS implantation. In advanced disease corneal surgery, including deep lamellar keratoplasty or penetrating keratoplasty, may be needed.