Keratoconus is a condition of the cornea in which there is progressive central thinning of the cornea changing it from dome-shaped to cone-shaped. Keratoconus comes from the Greek word meaning conical cornea. The cornea is the clear window of the eye. Abnormalities of the cornea can greatly affect the way we see the world.

Keratoconus is not a blinding disorder, but does result in increasing near-sightedness (things far away are out of focus) and irregular astigmatism (things look tilted) that can significantly distort your vision. It is almost always bilateral (affecting both eyes). It is a slowly progressive disorder, taking years to develop, and may halt at any stage from mild to severe.

Some cases of keratoconus have a hereditary component and studies indicate that about 8% of patients have affected relatives. However, most cases appear to be sporadic. It has been suggested that there is less than a 1 in 10 chance of having a child with some degree of keratoconus if one of the parents have keratoconus without a family history. The actual incidence of keratoconus is uncertain, large studies estimate 50 - 230 per 100,000.

Keratoconus usually has its onset in puberty with progression over a 10 to 20 year period. This rate of progression is variable as well as the severity, ranging from mild astigmatism to severe corneal thinning, protrusion, and scarring.

Patients with keratoconus initially notice visual blurring and distortion. This may be accompanied by photophobia (light sensitivity) and glare. Patients may note the need for frequent changes in their glasses. In the advanced stages, there may be a precipitous drop in vision due to clouding of the cornea, referred to as acute corneal hydrops. This condition usually resolves over weeks to months but is often followed by central corneal scarring.

Treatment of keratoconus depends on the severity of the condition. Initially, eyeglasses are often successful in improving vision; however, as the disease advances contact lenses are required to provide optimal visual correction. Contact lens fitting can be difficult in patients with keratoconus requiring frequent visits and lens changes. Lastly, when good vision can no longer be attained with contact lenses or intolerance to the contact lens develops, corneal transplantation is recommended. This is only necessary in about 10% of patients with KC and carries a success rate of greater than 90%, one of the highest for corneal transplantation. Although this procedure replaces the thinned central portion of the corneal, eyeglasses and contact lenses are often required for maximal visual acuity.

An advanced case of keratoconus where the ectasia of the cornea causes the lower lid to be tented outwards.

This page was last modified on Wednesday, February 25, 2009