What is keratoconus?

Keratoconus is an irregular protrusion of the cornea, the clear surface over the colored part of the eye. The cornea acts like the windowpane to the eye. If this windowpane is not smooth, the light will not bend evenly and an irregular image will be formed. Like looking through a bumpy piece of glass.

During the early stages of this disease, vision may still be correctable to 20/20 with glasses. The only clue to a keratoconus diagnosis may be from corneal measurements or corneal map. A topographical map of the cornea will show the high and low spots on the cornea, much like a topographical map of the earth will show the mountains and oceans.

As this disease progresses, vision will no longer be correctable with glasses. Iron will deposit around the base of the protrusion. The tissue will thin and a scar may develop. In severe cases, a temporary painful condition called acute hydrops may occur when water rushes into the thinned area of the cornea. This will lead to severe scarring.

Diagnosing keratoconus

About one in 2000 people will develop keratoconus. Most people will have a mild or moderate form of the disease. Only 10% of keratoconics will develop the most severe form. It typically is diagnosed in the late teens or twenties. However, many people have been diagnosed in their mid to late thirties; this is usually a more mild form of the disease. One eye will precede the other and they will progress at uneven rates. The eyes may go for long periods of time without any change and then may change dramatically over a period of months.

Managing keratoconus

A contact lens is the most highly effective way to manage keratoconus and 90% of all cases can be managed this way indefinitely. If the cornea becomes too scarred or painful, a corneal transplant may be necessary. A gas permeable lens covers the irregular protrusion on the cornea and makes a new smooth surface for the light to bend through. In many cases a special design must be used. The back surface of the lens is designed to fit the contour of the protrusion, much like fitting a hat to a head. It is important for a patient with keratoconus to follow-up with his/her eye doctor at a minimum of 6 month intervals to make sure there has been no change to the cornea or contact lens. These contact lenses are not cosmetic. They are a prosthetic device and should be covered as any medical/prosthetic device is covered under the patient's insurance policy. Use of contact lenses may postpone or eliminate the need for future, more costly and dangerous, surgical intervention.

Last reviewed: 
October 2021

Interested in using our health content?