Keratoconus

Progressive corneal thinning into a cone shape

Overview

Keratoconus is a progressive eye disease in which the cornea thins and bulges forward into a cone shape, causing increasing irregular astigmatism and distorted vision. It usually begins in the teens or early twenties and may progress for years before stabilizing. Both eyes are typically affected, often asymmetrically. Associations include vigorous eye rubbing, atopic conditions such as allergies and eczema, Down syndrome, and connective tissue disorders, and a family history is common. Spectacles may suffice early on, but as the cornea becomes irregular, rigid gas permeable or scleral contact lenses are typically needed to provide a smooth optical surface. Corneal collagen cross linking, which uses riboflavin and ultraviolet light to stiffen the cornea, was developed in the late 1990s to halt progression. Advanced cases with scarring or contact lens intolerance may require a corneal transplant, either deep anterior lamellar or penetrating keratoplasty, and keratoconus has long been one of the leading indications for corneal grafting.