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For someone without astigmatism, the eye is shaped like a basketball. When an individual has astigmatism, the surface of the eye is curved more like a rugby ball, with both flatter and steeper curves.
Astigmatism distorts or blurs vision for objects at any distance. Blurry vision from astigmatism is similar to the effect of "funhouse" mirrors in which you appear too tall, too wide, or too thin. Large amounts of astigmatism are usually inherited, may be present at birth, and frequently remain unchanged throughout life. Small amounts of astigmatism are very common and may be acquired any time in life which often do not require correction with glasses or contact lenses.

Correction of astigmatism is not difficult if the distortion proceeds in a regular direction across the cornea. A similar but opposite curve can be made in prescription glasses to neutralize or offset the distortion of the cornea. However, if the cornea has been injured or scarred, the corneal distortion may be irregular. So-called irregular astigmatism is more difficult to correct and can by improved only by reshaping the corneal surface. This may be accomplished either by wearing a hard contact lens, or by performing a corneal transplant, which involves removing the scarred cornea and replacing it with donated human corneal tissue.
Hard or gas-permeable contact lenses improve astigmatism better than soft contact lenses, but special soft contact lenses which correct mild astigmatism are sometimes helpful. If the amount of astigmatism is very large, glasses that correct the condition may cause some diction of peripheral vision. Very large amounts of astigmatism are not easily corrected with a contact lens, since the lens may wobble on the wavy surface of the cornea. In such instances, a special toric contact lens may be ground with a curve in the back surface to stabilize the lens on the cornea.

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