Difference between revisions of Astigmatism

Astigmatism is caused by an irregularly shaped cornea or lens. The first is called corneal astigmatism, which is the more common form, and the second is called lenticular astigmatism. "Regular" astigmatism is often described as a having the cornea shaped like a rugby ball, rather than spherical like a basketball. The optics of an ''idealised'' lens of such a form would cause incoming light on different planes (corresponding to the two principal axes of the lens) to be focused at different offsets beyond the lens.