Astigmatism is a scary-sounding name for a relatively common eye problem. Astigmatism (AY-stig-mah-tis-um) simply means that the eyeball is shaped like a football rather than a basketball, like most eyes. Having a more oval shape to the eye makes the light coming into the eye bend in such a way that it does not land directly on the retina and leads to blurry vision.

People with astigmatism may also be nearsighted or farsighted. Astigmatism affects about 1 in 3 people in the United States.¹

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What Causes Astigmatism?

Doctors aren’t exactly sure what causes astigmatism. But they do know that the risk of having astigmatism is passed down from parent to child. So if one or both of your parents has astigmatism, you’re more likely to have astigmatism.

Some babies are born with it, while others develop it in childhood or adolescence. Adults can develop astigmatism as a result of an eye injury or surgery.

There is no way to prevent astigmatism.

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What Are the Symptoms of Astigmatism?

Common symptoms include: 

• Blurry vision
• Difficulty reading things up close and far away
• Eye strain
• Squinting
• Trouble seeing things at night
• Headaches

If you have mild astigmatism, you may not even know you have it until an eye doctor tells you. That’s why regular eye exams are so important.

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How Is Astigmatism Diagnosed? 

Astigmatism is diagnosed through a comprehensive eye exam. Your doctor will perform various tests that measure your eyes and vision. They’ll also check for other refractive errors like nearsightedness and farsightedness.

If you have astigmatism, it is noted on your eyewear prescription in the CYL or CYLINDER column. It is written as either a positive or negative number, depending on your degree of astigmatism. If you don’t have astigmatism, your eye doctor will either leave the CYL column blank or may write the letters DS, which means no astigmatism.

(Learn how to read your eyewear prescription.)

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How Is Astigmatism Treated?

Mild astigmatism may not need any correction or treatment at all.

If astigmatism interferes with vision, your eye doctor will usually recommend glasses or contact lenses.

Eye surgery is another option for treating astigmatism and other refractive errors. Procedures like LASIK reshape the cornea to improve vision.

Your eye doctor will recommend the right treatment based on your vision needs, preferences, and lifestyle.

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¹Vitale S, Ellwein L, Cotch MF, Ferris FL 3rd, Sperduto R. Prevalence of refractive error in the United States, 1999-2004. Arch Ophthalmol. 2008 Aug;126(8):1111-9. doi: 10.1001/archopht.126.8.1111. PMID: 18695106; PMCID: PMC2772054.