Keratoconus is a progressive eye disease in which the normally round cornea thins and begins to bulge into a cone-like shape. This cone shape deflects light as it enters the eye on its way to the light-sensitive retina, causing distorted vision.
Keratoconus can occur in one or both eyes and often begins during a person’s teens or early 20s.
As the cornea becomes more irregular in shape, it causes progressive nearsightedness and irregular astigmatism to develop, creating additional problems with distorted and blurred vision. Glare and light sensitivity also may occur.
Patients often first require glasses, then contact lenses, and, if the condition progresses to a severe level, a corneal transplant may be required.
Corneal ectasia is one of the most devastating complications after Laser In situ Keratomileusis (LASIK). Post-LASIK ectasia is considered in patients who developed increasing myopia, with or without increasing astigmatism, loss of uncorrected visual acuity, often loss of best-corrected visual acuity, with keratometric steepening, with or without central and paracentral corneal thinning, and topographic evidence of asymmetric inferior corneal steepening after LASIK procedure.
Ectatic changes can occur as early as 1 week or can be delayed up to several years after LASIK. The actual incidence of ectasia is undetermined, although the incidence rate of up to 0.6% has been reported.
CrossLinking also treats other corneal ectatic disorders such as keratoglobus, a rare noninflammatory corneal thinning disorder, characterised by generalised thinning and globular protrusion of the cornea, pellucid marginal degeneration, a bilateral, noninflammatory disorder, characterized by a peripheral band of thinning of the inferior cornea, posterior keratoconus, a rare condition, usually congenital, which causes a nonprogressive thinning of the inner surface of the cornea, while the curvature of the anterior surface remains normal and Terrien’s marginal degeneration, a painless, noninflammatory, unilateral or asymmetrically bilateral, slowly progressive thinning of the peripheral corneal stroma.