Corneal surgery is performed to change the shape of the cornea which will correct vision problems such as myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. Corneal surgeries performed for this purpose may include radial keratotomy, photorefractive keratectomy (PRK), laser-assisted in-situ keratomileusis (LASIK), keratomileusis, keratophakia, and epikeratoplasty.
Phototherapeutic keratectomy (PTK) involves the use of the excimer laser to treat visual impairment or irritative symptoms relating to diseases of the anterior cornea. PTK functions by removing anterior stromal opacities or eliminating elevated cornea lesions while maintaining a smooth corneal surface.
Intrastromal corneal ring segments (i.e., INTACS) when provided in accordance with the Humanitarian Device Exemption (HDE) specifications of the U.S. Food and Drug Administration (FDA), consist of micro-thin methylmethacrylate inserts of variable thickness that are implanted on the perimeter of the cornea. They are used in refractive surgery to correct mild myopia (see above), and as a treatment of keratoconus. The inserts help restore vision in keratoconus individuals by flattening and repositioning the cornea.
Corneal collagen cross-linking (CXL) is a photochemical procedure for the treatment of progressive keratoconus and corneal ectasia. Keratoconus is a dystrophy of the cornea characterized by progressive deformation (steepening) of the cornea while corneal ectasia is keratoconus that occurs after refractive surgery. Both lead to functional loss of vision and the need for corneal transplantation.