Astigmatism is an abnormal curvature of the clear outer covering of the eye (cornea), causing blurry vision.

The cornea directs light rays into the eye and focuses them on the light-sensitive retina at the back of the eye. If the surface of the cornea is irregular, light rays may not focus properly on the back of the eye.

Vision problems caused by astigmatism can be treated with eyeglasses, contact lenses, or surgery.