Ideally, the cornea - the front surface of the eye - and the anterior surface of the human lens are round like half a basketball. If the eye has two different curves like half a football, the images come into the eye in a distorted fashion and give a blurred image. This distortion is called astigmatism
An individual who has astigmatism has an abnormal curve in the optical part of the eye. The abnormal curve is usually in the cornea, but sometimes the lens is involved. When light enters the eye, it produces a smeared image rather than an image in sharp focus.
Symptoms of astigmatism include blurred vision, objects that appear fatter or taller than they really are, and a smeared focus.
Astigmatism usually occurs naturally. It is caused by an abnormal curvature or shape of the cornea or lens. Injury to the cornea, or any other factor that could change the shape of the cornea or lens, can also cause astigmatism.
There is no way to prevent astigmatism. The eye develops this way in some people.
Diagnosis is usually made by an eye-care professional during an eye exam. It can also be diagnosed using instruments that measure the curve of the cornea. Other instruments can make a map of the cornea.
There are no permanent effects to vision that cannot be corrected by eyeglasses or other optical devices.
Glasses or contact lenses can be prescribed to control the light coming into the eye. The glasses or contact lenses direct the light to a point focus on the retina, so the image does not appear smeared.
Recently, corneal surgery procedures have become recognized as a possible treatment for astigmatism. Cuts in the cornea or the use of lasers or other surgical techniques on the cornea have been shown to reduce or eliminate astigmatism.
Rarely, the astigmatism is due to multiple irregular curves in the cornea. This progressive degenerative condition of the young is called keratoconus. Keratoconus is corrected with specially designed rigid contact lenses, or by corneal transplantation.
Contact lenses may cause injury to the cornea. Surgery may be complicated by bleeding, infection, or reactions to anesthesia.
Once astigmatism is corrected, the person will have normal vision.
Astigmatism is monitored during routine eye examinations. Any new or worsening symptoms should be reported to the healthcare professional.