Astigmatism is an optical condition where the focus of an image entering the eye on one plane or angle is different from the focus of that same image entering the eye from another angle. For example, the clarity of vertical images is less clear than those from horizontal images.
The most common cause of astigmatism is from the cornea (the clear “window” or dome of the eye covering the pupil and iris). An astigmatic cornea is one that is not perfectly spherical, rather it is shaped more like that of a football. A spherical, or non-astigmatic, cornea is more like that of a basketball.
Uncorrected, astigmatism affects both near and distant vision, resulting in round lights appearing more oval or ellipsoidal in appearance, based on the amount of astigmatism present. The direction in which the football shaped cornea is angled determines the direction of the oval-appearing distortion that one sees.
Some astigmatism runs in families, some astigmatism can occur as a natural aging process (the cornea is made of protein and our protein loses elasticity as we age accounting for both sagging body parts as well as sagging corneas), and some astigmatism can result from trauma or surgery . Astigmatism correction can usually be accomplished with glasses, contacts or refractive surgery.
