Astigmatism is an abnormality of the eye that distorts vision.
Causes: According to the American Optometric Association, astigmatism usually means that the curvature of the cornea, the outer layer of the front of the eye, is irregularly shaped. The eye can't focus clearly. This can also be caused by the curvature of the eye's lens. The condition appears to be genetic in some people, though researchers aren't sure of the exact cause. It often occurs with nearsightedness or farsightedness.
Symptoms: Parts of a person's vision field may be fuzzy or out of focus. Eyes may tire easily.
Treatment: Generally an eye doctor will prescribe glasses or contact lenses to correct the problem.