Astigmatism is a mild and easily treatable imperfection in the curvature of your eye. The condition can result in blurred vision. The eye has two parts that focus images — the front surface of your eye (cornea), and the lens inside the eye. 

In a perfectly shaped eye, each of these focusing elements has a perfectly smooth curvature like the surface of a rubber ball. A cornea or lens with such a curvature bends all incoming light the same way and makes a sharply focused image on the back of your eye (retina).

Astigmatism occurs when the cornea or the lens has a slightly different curvature in one direction than the other, similar to the surface of a football. When the cornea has such a shape, you have corneal astigmatism. When the lens has such a shape, you have lenticular astigmatism. Either type of astigmatism can cause blurred vision.

Astigmatism blurs your vision at all distances. Astigmatism is usually present from birth and may occur in combination with nearsightedness (myopia) or farsightedness (hyperopia). The condition tends to remain constant, neither improving nor deteriorating much over time.

Most people have some degree of astigmatism. Often it's not pronounced enough to require corrective action. Astigmatism isn't caused or made worse by reading in poor light, sitting too close to the television or squinting.

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