Encyclopedia / K / Keratoconus



This is a conical protrusion of the central part of the cornea, resulting in an irregular astigmatism. "Kerato" is the word for cornea.


Keratoconus is a progressive ectasia (expansion or dilatation) of the cornea, usually bilateral, beginning between ages 10 and 20. The disorder progresses slowly and occurs in three forms: keratoconus posticus circumscriptus, autosomal dominant keratoconus, and autosomal recessive keratoconus.


Keratoconus occurs in females slightly more than in males. One long-term study indicated a prevalence of 54.5 diagnosed cases of keratoconus per 100,000 population.

Keratoconus results from an inherited corneal abnormality, an injury of the eye (e.g., hard contact lens use for many years), diseases of the eye such as retinitis pigmentosa, or retinopathy of prematurity, or other disorders such as Noonan syndrome, Down's syndrome, Ehlers-Danlos syndrome, and Leber's congenital amaurosis.


Initially most people can correct their vision with eyeglasses. But as the astigmatism worsens, they must rely on specially fitted contact lenses to reduce the distortion and provide better vision. There may be moderate or severe distortion (astigmatism) and blurry (near- and farsighted) vision. Symptoms may be unilateral initially and may later become bilateral.


In most people, the cornea will stabilize after a few years without ever causing severe vision problems. Treatment of the visual defect may involve the use of hard contact lenses as a temporary measure. The only "cure" is corneal transplant (penetrating keratoplasty or epikeratoplasty).

For patients with no scarring near the center of the cornea, another option may be surgically grafting a layer of epithelial cells to flatten the cone-shaped cornea in a process called epikeratophakia. It has results comparable to corneal transplantation and, if it is unsuccessful, it can be followed by corneal transplantation.

Genetic counseling may be of benefit for patients with an inherited form of keratoconus.


What is causing this problem?

Is it hereditary?

Is a surgical procedure indicated?

Which procedure would be used?

Would contact lenses help?

Will the condition get worse?