Reviewed by Christopher T. Hood, M.D.

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What Is Keratoconus?

Keratoconus, meaning "cone-shaped," is a condition in which the cornea (the clear front window of the eye) progressively becomes steeper and thinner. This abnormal shape of the cornea can cause distortion of visual images.


  • Frequent changing of glasses or contact lens prescriptions with high levels of astigmatism
  • Blurring and distortion of vision
  • Glare
  • Light sensitivity and irritation

The symptoms described above may not necessarily mean that you have keratoconus. However, if you experience one or more of these symptoms, contact your ophthalmologist for a complete exam.


The cause of keratoconus is unknown. It usually appears in individuals during their late teens or early twenties. The disease usually progresses for 10 to 20 years as the cornea steepens and thins. Although both eyes may be affected, one eye is usually worse than the other.

Risk Factors

Genetics may contribute to your risk of developing keratoconus.  Vigorous eye rubbing is thought to add to development and progression of the disease; therefore patients with keratoconus are advised to avoid rubbing their eyes.

Tests and Diagnosis

Signs of keratoconus can be seen during a routine eye examination. These may include high degrees of astigmatism when checking a glasses prescription, or changes in the cornea as seen through the slit lamp microscope during an examination.  The diagnosis is often confirmed using corneal topography, photographs that measure the curvature of the cornea and highlight irregularities consistent with keratoconus.

Treatment and Drugs

Although there are no medicines known that will prevent progression of the disease, mild cases of keratoconus can be successfully treated with glasses or specially designed contact lenses. A customizable oversized hard contact lens device called Prosthetic Rehabilitation of the Ocular Surface Ecosystem (PROSE) can also improve vision for many patients with keratoconus.  When vision is no longer satisfactory with glasses or contact lenses, a corneal transplant may be recommended. In addition, intracorneal rings have been approved by the FDA for the treatment of keratoconus. These crescent-shaped plastic rings are surgically placed into the outer edges of the cornea.  Collagen cross-linking is a new treatment that strengthens the cornea and may slow the progression of keratoconus.  This treatment is currently being studied by the FDA and is not yet commercially available in the United States. A Collagen Crosslinking Study is being conducted at Kellogg. Information about this study can be found on our Clinical Trials page.

Clinic Information

For more information, see the Cornea & External Disease, Cataract and Refractive Surgery Clinic, and the complete Clinic Services listing of the U-M Kellogg Eye Center.

Last Modified: Wednesday, 13-Jan-2016 11:12:37 EST