Astigmatism is a very common eye condition and is easily corrected by eyeglasses or contact lenses.  Most of us have some degree of astigmatism.  Astigmatism results in blurred vision at all distances. It is known as a refractive disorder of the eye.  Refraction is the bending of light.  When a light wave enters the eye, it is bent by the cornea as it makes its way through to land on the retina.  The cornea, lens and retina contribute to clear vision at all distances.  In astigmatism, vision is blurred due to either an irregularly shaped cornea or lens.

Corneal astigmatism is common and caused by an irregularly shaped cornea.  The cornea is normally symmetrical and round, but in astigmatism the cornea can become elongated like a football.  This causes the light rays to split in the eye, never achieving a singular point of focus.  Why some people are born with an elongated cornea is unknown.  Some studies show that it could be hereditary.  Keratoconus, a disease of the eye that causes a thinning of the cornea to occur, can cause astigmatism by changing the shape of the cornea.

Onset and Treatment
Astigmatism usually reveals itself early.  While slight cases astigmatism may not need to be corrected, large amounts of astigmatism can cause blurred vision, headaches and eye strain.  People who have myopia, nearsightedness, or hyperopia, farsightedness, are likely to have some degree of astigmatism.  Myopia, hyperopia and astigmatism are all known as refractive disorders as they affect the way that the eye is able to bend, or refract, light rays onto the retina. A complete eye exam will test for astigmatism.

A diagnosis of astigmatism can be made during the course of comprehensive eye exam.  A phoropter allows the doctor to show a series of lenses to a patient, switching back and forth between them to determine the best fit for corrective lenses. A keratometer, a devise to measure the curvature of the cornea, may be used as well.

There is no known way to prevent astigmatism.  Taking frequent breaks while doing close work allows the ocular muscles to unwind and can help ward off eye strain.  Try looking off into the distance every ten minutes or so to keep your eyes relaxed.  Wearing sunglasses to prevent UV damage to the eyes helps keep vision sharp later in life.  If you are experiencing headaches, fatigue, eye strain or blurred vision, you may have astigmatism and should be examined by an optometrist or ophthalmologist.  Always see an eye care professional immediately if you have any sudden changes in vision.  This includes darkening around the edges of your vision, dark spots in front of your eyes, halos around bright lights, a loss of vision in one part of your field of sight or any other noticeable change.