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by Scholten A

Definition

Keratoconus is when the cornea of the eye thins out and bulges. The cornea is a clear dome over the eye.

This condition can cause problems with eyesight and tends to get worse over time. Early treatment can improve outcomes.

Causes

The exact cause of keratoconus is not known. It may be due to genes, environment, and biology.

Risk Factors

Keratoconus usually starts in teens and young adults. Other things that raise the risk are:

  • Rubbing the eyes
  • Floppy eyelid syndrome
  • Trauma to the eye from contact lenses
  • Allergies
  • A family history of keratoconus

Symptoms

Symptoms of keratoconus tend to worsen slowly for about 10 to 20 years. In the early stages, symptoms may be:

  • Mildly blurred eyesight
  • Straight lines look slightly wavy or bent
  • Sensitivity to light

In later stages, eyesight may become more blurred. Other symptoms may be:

  • Problems seeing objects that are far away
  • Glasses and contact lenses no longer help eyesight
  • Problems wearing contact lenses

Severe disease can lead to sudden loss of eyesight, eye pain, and infection. This is rare.

Diagnosis

The eye doctor will ask about symptoms and past health. A complete eye exam will be done. Sometimes keratoconus is found before there are symptoms.

Tests will be done to look at the cornea. They may include:

  • Corneal tomography—images taken to see the thickness
  • Corneal topography—images taken to see the shape
  • Slit lamp exam—to look for defects
  • Pachymetry—to measure thin areas

Tests will confirm the diagnosis.

Treatment

The goal is to prevent symptoms from getting worse and correct eyesight. Treatment depends on the stage of the disease and other conditions.

For mild to moderate disease, eyesight may be corrected with:

  • Glasses
  • Special contact lenses that flatten the cornea

Proper eye care, such as not rubbing the eyes will also help.

If glasses or contact lenses do not help, options may be:

  • Corneal cross-linking (CXL)— UVA light and vitamin B2 eyedrops are used to strengthen the cornea. This may slow or stop the condition.
  • Keratectomy— Laser is used to reshape the cornea. It is used along with CXL.

Other options are implanted devices to flatten the cornea. They include:

  • Corneal rings
  • Lens implants

For severe disease, a corneal transplant may be done. All or part of the diseased cornea is replaced with healthy tissue from a donor.

Prevention

There are no known guidelines to prevent keratoconus.

RESOURCES

American Academy of Ophthalmology  https://www.aao.org 

American Optometric Association  https://www.aoa.org 

CANADIAN RESOURCES

Canadian Ophthalmological Society  https://www.cos-sco.ca 

Canadian Ophthalmological Society  https://www.cos-sco.ca 

References

Andreanos KD, Hashemi K, et al. Keratoconus treatment algorithm. Ophthalmol Ther. 2017;6(2):245-262.

Keratoconus. American Optometric Association website. Available at: https://www.aoa.org/healthy-eyes/eye-and-vision-conditions/keratoconus?sso=y. Accessed August 3, 2021.

Keratoconus. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/keratoconus. Accessed August 3, 2021.

Keratoconus. Johns Hopkins Medicine website. Available at: https://www.hopkinsmedicine.org/health/conditions-and-diseases/keratoconus. Accessed August 3, 2021.

What is keratoconus? American Academy of Ophthalmology website. Available at: https://www.aao.org/eye-health/diseases/what-is-keratoconus. Accessed August 3, 2021.

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