OHSU

Astigmatism

Astigmatism is characterized by an irregular curvature of the cornea that makes objects appear blurry up close and at a distance. This type of disorder is called a refractive error. Almost everyone has some degree of astigmatism.

Your eye is naturally shaped like a sphere, or ball. Under normal circumstances, when light enters the eye, it refracts (bends) evenly, creating a clear view of the object. However, the eye of a person with astigmatism is shaped more like a football or the back of a spoon. When light enters the eye, it is refracted more in one direction than the other, allowing only part of the object to be in focus at one time. Objects at any distance can appear blurry.

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Causes

Astigmatism can be hereditary and is often present at birth. It can also result from pressure of the eyelids on the cornea, incorrect posture or an increased use of the eyes for close work.

Symptoms

People with undetected astigmatism often have headaches, fatigue, eyestrain and blurred vision. While astigmatism may not be the cause of these symptoms, you should schedule an eye examination if you experience one or more.

Because astigmatism get worse over time, you should see an optometrist or ophthalmologist for a regular eye exam. Optometrists are trained to improve visual acuity by prescribing glasses or contact lenses. Ophthalmologists provide all types of eye care, from examinations and vision correction to diagnosis and treatment with medication and surgery.

Treatment

Almost all degrees of astigmatism can be corrected with glasses or contact lenses. If you have only slight astigmatism and no other eye conditions, you may not need corrective lenses at all. If you have moderate to high astigmatism, you probably need corrective lenses.

  • Corrective lenses (glasses or contact lenses). For astigmatism, special corrective lenses called toric lenses are prescribed. Toric lenses have greater light-bending power in one direction than the other. After performing various tests, your eye doctor will determine the right toric lens prescription for your astigmatism.

  • Refractive surgery. Another way to correct astigmatism is by changing the shape of the cornea through refractive surgery. Since there is more than one type of refractive surgery, your doctor can help you choose a treatment that is right for you.