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 20s.
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
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.