You may have astigmatism and not even know it. Even people who have never worn glasses or contacts can have astigmatism in the cornea that only becomes visually apparent after the natural lens or cataract is removed. It can occur along with nearsightedness and farsightedness and, if present, will blur your vision at all distances.
There are two main types of astigmatism: corneal and lenticular. Corneal astigmatism is present when the cornea, or outer window of the eye, is more curved in one direction than the other, like the shape of a football. Small amounts of corneal astigmatism can be neutralized or minimized by the shape of the natural lens inside the eye, which is why some people have astigmatism and never knew it.