Astigmatism is not merely not having 20/20 vision. It is caused by an irregularly shaped cornea and is corrected with eyeglasses, contact lenses or refractive surgery. Sometimes incorrectly called a "stigmatism," astigmatism may accompany nearsightedness or farsightedness. Simply put, near or farsightedness is caused by a mis-shaped eyeball; astigmatism is caused by a mis-shaped lense and you can one condition with or without the other.
Regardless, at least in the U.S., most eye problems are not a problem for the FAA as long as you are corrected to 20/40 (for a Class III) or 20/20 (Class I & II
[Edited 2003-10-15 16:41:16]