Astigmatism is caused by an irregular curvature of the cornea or lens. A cornea without significant astigmatism is shaped like the side of a basketball (the curvature is uniform over the entire surface). A cornea with astigmatism is shaped more like the side of a football (with the curvature being short and steep in one direction and long and flat in the other). Astigmatism distorts rays of light in a way that is similar to a funhouse mirror, making objects look wider, taller or thinner than they really are. Astigmatism is very common. In fact, most people have some degree of astigmatism. In most cases, people with astigmatism are born with this condition. The reason why corneal shape differs from person to person is unknown, but the likelihood of developing astigmatism is inherited. Sometimes, astigmatism can develop after an eye disease, eye injury or surgery.
When the cornea has an irregular shape, it is called corneal astigmatism. When the shape of the lens is distorted, you have lenticular astigmatism. As a result of either type of astigmatism, your vision for both near and far objects appears blurry or distorted. Astigmatism may be combined with other refractive errors such as nearsightedness (myopia) or farsightedness (hyperopia). While adults with a higher degree of astigmatism may realize their vision is not as good as it should be, children who have astigmatism symptoms may not be aware they have this condition and are unlikely to complain about blurred or distorted vision.
Astigmatism can be treated non-surgically with glasses or rigid or soft contact lenses. Astigmatism can also be corrected surgically using a variety of procedures, such as LASIK, PRK, as a part of cataract surgery using LRI’s (limbal relaxing incisions, which are only for very low degrees of astigmatism), or as a part of cataract surgery using specialized TORIC lens implants which can correct even very high degrees of astigmatism by putting the correction inside the eye.