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Astigmatism

Authors:
  • Alison N. Haughton, MA
Publication Type:

Condition

Astigmatism

Definition

Astigmatism is a condition that results in blurred, unfocused, or fuzzy vision. The cornea (front surface of the eye) or lens (located behind the cornea) has an abnormal or irregular curve.

There are 2 common types of astigmatism:

  • Corneal astigmatism—misshapen cornea
  • Lenticular astigmatism—misshapen lens
Normal Anatomy of the Eye.

Copyright © 2002 Nucleus Communications, Inc. All rights reserved.

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Causes

The precise cause of astigmatism is unknown. It is often present at birth and may occur with nearsightedness or farsightedness. Sometimes it may occur after an injury or eye surgery.

Risk Factors

Things that may raise the risk of astigmatism include:

  • Heredity—a family history of astigmatism, eye disease, or disorders such as keratoconus
  • Eye surgery—some types of eye surgery, such as cataract removal
  • A history of corneal scarring or thinning

Symptoms

Some people with astigmatism may have no symptoms. In those who do have symptoms, astigmatism may cause:

  • Blurred or distorted vision, which may cause you to squint
  • Headaches
  • Lightheadedness

Symptoms vary depending on the extent of the astigmatism.

Diagnosis

The doctor will ask about symptoms and health history. An examination of the eyes will be done.

Tests to check the eyes may include:

  • Visual acuity assessment test (VAT)—to check distant vision
  • Refractor test
  • Keratoscope—to detect and measure the presence of corneal surface curvature

Treatment

The goal of treatment is to improve vision. This may be done with:

Prevention

There are no current guidelines to prevent astigmatism. Be sure to see the eye doctor for regular check-ups.

Corrective Lenses

Glasses or toric contact lens may be prescribed to help improve vision.

RESOURCES:

CANADIAN RESOURCES:

CANADIAN RESOURCES:

References

  • Astigmatism. American Academy of Ophthalmology website. Available at: https://www.aao.org/eye-health/diseases/what-is-astigmatism.
  • Astigmatism. American Optometric Association website. Available at: https://www.aoa.org/patients-and-public/eye-and-vision-problems/glossary-of-eye-and-vision-conditions/astigmatism.
  • Mozayan, E. and Lee, J. Update on astigmatism management. Current Opinion in Ophthalmology, 2014; 25 (4): 286-90.
  • Facts About Astigmatism. National Eye Institute website. Available at: https://nei.nih.gov/health/errors/astigmatism.
  • Refractive errors in children. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/refractive-errors-in-children.
Last Updated:
2023-06-01

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This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.