Keratoconus is a vision disorder that occurs when the normally round
cornea (the front part of the eye) becomes thin and irregular (cone) shaped.
This abnormal shape prevents the light entering the eye from being focused
correctly on the retina and causes distortion of vision.
In its earliest stages, keratoconus causes slight blurring and distortion of
vision and increased sensitivity to glare and light. These symptoms usually
appear in the late teens or late twenties. Keratoconus may progress for 10-20
years and then slow in its progression. Each eye may be affected differently. As
keratoconus progresses, the cornea bulges more and vision may become more
distorted. In a small number of cases, the cornea will swell and cause a sudden
and significant decrease in vision. The swelling occurs when the strain of the
cornea's protruding cone-like shape causes a tiny crack to develop. The swelling
may last for weeks or months as the crack heals and is gradually replaced by
scar tissue. If this sudden swelling does occur, your doctor can prescribe
eyedrops for temporary relief, but there are no medicines that can prevent the
disorder from progressing.
Eyeglasses or soft contact lenses may be used to correct the mild
nearsightedness and astigmatism that is caused by the early stages for
keratoconus. As the disorder progresses and cornea continues to thin and change
shape, rigid gas permeable contact lenses can be prescribed to correct vision
adequately. In most cases, this is adequate. The contact lenses must be
carefully fitted, and frequent checkups and lens changes may be needed to
achieve and maintain good vision.
In a few cases, a corneal transplant is necessary. However, even after a
corneal transplant, eyeglasses or contact lenses are often still needed to
correct vision.
