What is Keratoconus?
Keratoconus is a deterioration of the structure of the cornea with gradual bulging from the normal round shape to a cone shape.
Alternative names
Causes
The cause is unknown. Keratoconus is more common in contact lens wearers and people with nearsighted eyes. Some researchers believe that allergy may play a role.
What is Keratoconus?
Keratoconus is a deterioration of the structure of the cornea with gradual bulging from the normal round shape to a cone shape.
Causes
The cause is unknown. Keratoconus is more common in contact lens wearers and people with nearsighted eyes. Some researchers believe that allergy may play a role.
Symptoms & Signs
This condition causes decreased visual acuity. The earliest symptom is subtle blurring of vision that cannot be corrected with glasses. (Vision can generally be corrected to 20/20 with gas-permeable contact lenses.)
Exams and Tests
Keratoconus is frequently discovered during adolescence. It can usually be diagnosed with slit-lamp examination of the cornea. Early cases may require a test called corneal topography, which creates a map of the curvature of the cornea.
When keratoconus is advanced, the cornea may be thinner in areas. This can be measured with a painless test called pachymetry.
Treatments
Contact lenses are the primary treatment and are satisfactory treatment for most patients with keratoconus. Severe cases may require corneal transplantation.
Newer technologies may use high frequency radio energy. This energy shrinks the edges of the cornea, which pulls the central area back to a more normal shape. It can help delay or avoid the need for a corneal transplantation.
Prognosis
In most cases vision can be corrected with gas-permeable contact lenses. Where corneal transplantation is needed, results are usually good after a long recovery period.
Possible Complications
Patients with keratoconus should not have laser vision correction. Corneal topography is usually done before laser vision correction to rule out people with this condition.
When to contact a medical professional
Young persons whose vision cannot be corrected to 20/20 with glasses should be evaluated by an eye doctor experienced with keratoconus.
Prevention
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.
References
Kymionis GD, Siganos CS, Tsiklis NS, et al. Long-term follow-up of Intacs in keratoconus. Am J Ophthalmol. Feb 2007;143(2):236-244.
Fay A. Diseases of the visual system. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 449
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (www.hon.ch). The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- 2008 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
Review Date: .8/22/2008
Reviewed By: Paul B. Griggs, MD, Department of Ophthalmology, Virginia Mason Medical Center, Seattle, WA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.8/22/2008
