MedlinePlus Medical Encyclopedia: Astigmatism

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Astigmatism

Contents of this page:
Illustrations Definition Causes Symptoms Exams and Tests	Treatment Outlook (Prognosis) Possible Complications When to Contact a Medical Professional

Illustrations

Visual acuity test

Definition Return to top

Astigmatism is a condition in which the cornea (the clear covering of the front of the eye) has an abnormal curve, causing out-of-focus vision.

Causes 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.

Exams 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 the degree of their vision problem measured by a test that uses reflected light (retinoscopy).

Treatment Return to top

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

Outlook (Prognosis) Return to top

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

Possible 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.

When to Contact a Medical Professional 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: 8/8/2006

Updated by: Paul B. Griggs, MD, Department of Ophthalmology, Virginia Mason Medical Center, Seattle, WA. Review provided by VeriMed Healthcare Network.

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