The cause is unknown. Keratoconus is more common in contact lens wearers and nearsighted eyes. Some researchers believe that allergy may play a role.

There are no preventive measures. Some specialists believe that patients with keratoconus should have aggressive treatment of ocular allergy and should be instructed not to rub their eyes.

The earliest symptom is subtle blurring of vision not correctable with glasses. The vision is generally correctable to 20/20 with contact lenses.

Keratoconus can usually be diagnosed with slit lamp examination of the cornea. Early cases may require corneal topography, a test which involves making a stereo image which gives a topographic map of the corneal curvature. When keratoconus is advanced, the cornea may be thinner in areas and this can be measured by pachymetry.

Contact lenses are the primary treatment and are satisfactory treatment for most patients with keratoconus. Severe cases may require corneal transplantation.

Vision can be corrected in most cases with contact lenses. Where corneal transplantation is needed, results are usually good after a long recovery period.