MedlinePlus Medical Encyclopedia: Astigmatism

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Astigmatism

Contents of this page:
Illustrations Definition Causes, incidence, and risk factors Symptoms Signs and tests	Treatment Expectations (prognosis) Complications Calling your health care provider

Illustrations

Visual acuity test

Definition Return to top

Astigmatism is a condition in which the cornea of the eye is asymmetrically curved, causing out-of-focus vision.

Causes, incidence, and risk factors Return to top

The cause of astigmatism is unknown. It is usually present from birth, and often occurs together with nearsightedness or farsightedness. A minor degree of astigmatism is considered normal and does not require correction. Astigmatism is very common.

Symptoms Return to top

Difficulty in seeing fine detail, either close-up or from a distance.

Signs and tests Return to top

Astigmatism is easily diagnosed by a standard ophthalmic exam with refraction test. Special tests are not usually required. Children or others who cannot respond to questions can have their refractive error measured by a test using reflected light called retinoscopy.

Treatment Return to top

Glasses or hard contact lenses will correct astigmatism. Soft contact lenses do not work as well.

Expectations (prognosis) Return to top

Vision is usually normal with the correct glasses or contact lenses.

Complications Return to top

There are complications associated with contact lenses (including the risk of corneal abrasion), which may develop if contact lenses are used.
Unequal astigmatism may cause amblyopia.

Calling your health care provider Return to top

Call for an appointment with the health care provider or ophthalmologist if vision problems worsen or do not improve with glasses or contact lenses.

Update Date: 7/24/2004

Updated by: Edward B. Feinberg, MD, MPH, Professor and Chair, Department of Ophthalmology, Boston University School of Medicine, Boston, MA. Review provided by VeriMed Healthcare Network.

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