Astigmatism is the term for an irregularly shaped cornea (somewhat like a rugby ball, or American football), resulting in light rays focusing that focus on more than one point on the retina. This causes distortion of the object being viewed. Astigmatism is relatively common and with the astigmatic eye, the refractive elements do not focus light to a point. This occurs because the refractive surfaces cannot form a clear image of an object at any distance. The major cause of astigmatism is usually the cornea, but astigmatism of the lens can also occur.