Keratoconus is a disorder in which the cornea has a propensity to stretch. Over time, the corneal tissue thins and bulges, assuming a cone shape. 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 over time and affect each eye differently. As keratoconus progresses, the cornea bulges more and vision may become more distorted.

Eyeglasses or soft contact lenses may be used to correct the mild nearsightedness and astigmatism that is caused by the early stages of keratoconus. As the disorder progresses and the cornea continues to thin and change shape, rigid gas permeable contact lenses may be prescribed to adequately improve vision. Contact lenses must be fitted carefully. Frequent visits and lens changes may be needed to achieve and maintain good vision.

In some cases, a corneal transplant is necessary. However, after a corneal transplant, eyeglasses or contact lenses are still often needed to correct vision. There are new refractive procedures being developed to help treat this condition.