Definition: Astigmatism is a refractive error in which light rays fail to come to a single focus on the retina because of differing amounts of refraction in the various meridians of the eye. Astigmatism is usually considered corneal astigmastism or lenticular astigmatism. With astigmatism, the power of the eye is different in one direction compared to other direction, 90 degrees away. An eye with astigmatism may be shaped more oblong, like a football, rather than round, like a basketball.
Common Misspellings: "stigmatism"