Astigmatism is one of a group of eye conditions known collectively as "refractive errors." Astigmatism is caused by a change in shape in the cornea. The cornea should be spherical, like a ball. With astigmatism, the cornea is oval like a football instead.
Most astigmatic corneas have two curves – a steeper curve and a flatter curve. This causes light to focus on more than one point in the eye, resulting in blurred vision at distance or near. Astigmatism often occurs along with nearsightedness or farsightedness.
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