What is Astigmatism?

Astigmatism is an imperfection in the curvature of your eye’s cornea or lens. It may be helpful to think of the normal eye as being shaped like a basketball. With astigmatism, it's shaped more like an American football (egg- or oval-shaped).

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Normally, the cornea and lens are smooth and curved equally in all directions. This helps to focus light rays sharply onto the retina at the back of your eye. If your cornea or lens isn't smooth and evenly curved, light rays aren't refracted (bent) properly. Doctors call this a refractive error.

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When your cornea has a distorted shape, you have corneal astigmatism. When the shape of your lens is distorted, you have lenticular astigmatism. In either case, your vision for both near and far objects is blurry or distorted. 

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Uncorrected astigmatism can impact a child's ability to achieve in school and sports. It is crucial that children have regular eye exams. Get these exams to detect astigmatism and other vision problems as early as possible.

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What causes Astigmatism?

Astigmatism is caused by an irregular curvature of the eye's cornea or lens. If your cornea or lens isn't evenly curved, light rays aren't refracted properly. With astigmatism you have blurred or distorted vision at near and far distances.

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Astigmatism is very common. Doctors don't know why corneal or lens shape differs from person to person. They do know that likelihood of developing astigmatism is inherited. Astigmatism can also develop after an eye disease, eye injury or surgery.

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Information on page extracted from AAO