Keratoconus
 This disorder--a progressive thinning of the
cornea--is the most common corneal dystrophy in the
U.S., affecting one in every 2000 Americans. It is more
prevalent in teenagers and adults in their 20s.
Keratoconus arises when the middle of the cornea thins
and gradually bulges outward, forming a rounded cone
shape. This abnormal curvature changes the cornea's
refractive power, producing moderate to severe
distortion (astigmatism) and blurriness
(nearsightedness) of vision. Keratoconus may also cause
swelling and a sight-impairing scarring of the tissue.
Studies indicate that keratoconus stems from one of
several possible causes:
1. An inherited corneal abnormality. About seven percent
of those with the condition have a family history of
keratoconus.
2. An eye injury, i.e., excessive eye rubbing or wearing
hard contact lenses for many years.
3. Certain eye diseases, such as retinitis pigmentosa,
retinopathy of prematurity, and vernal
keratoconjunctivitis.
4. Systemic diseases, such as Leber's congenital
amaurosis, Ehlers-Danlos syndrome, Down syndrome, and
osteogenesis imperfecta.
Keratoconus usually affects both eyes. At first, 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. Although finding a comfortable contact
lens can be an extremely frustrating and difficult
process, it is crucial because a poorly fitting lens
could further damage the cornea and make wearing a
contact lens intolerable.
In most cases, the cornea will stabilize after a few
years without ever causing severe vision problems. But
in about 10 to 20 percent of people with keratoconus,
the cornea will eventually become too scarred or will
not tolerate a contact lens. If either of these problems
occur, a corneal transplant may be needed. This
operation is successful in more than 90 percent of those
with advanced keratoconus. Several studies have also
reported that 80 percent or more of these patients have
20/40 vision or better after the operation.
Information courtesy of National Eye Institute
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