Astigmatism: Symptoms and Causes

Astigmatism results in the blurring of all images, whether they are near or far. This usually occurs when the cornea   Cornea: The clear, curved surface at the front of the eye through which light enters the eye. Along with the sclera, the cornea provides external protection for the eye.   is shaped like a football with a steeper curve in one direction and a flatter curve in the other, rather than round like a basketball. This uneven shape causes light rays entering the eye to focus on more than one point, rather than only on the retina   Retina: The transmitter located at the back of your eye that sends the images to your brain.   as they should.


When you have astigmatism, images focus in more than one place in the eye, because your eye is shaped unevenly.

Astigmatism is very common, affecting about 1 in 3 people, and is usually present at birth.1 If you are nearsighted or farsighted, there's a good chance that you have a touch of astigmatism, too. A small degree of this refractive error   Refractive error: Vision problem caused by an imperfect optical system, most commonly myopia, hyperopia, and astigmatism.   is considered normal and does not require correction.

In mixed astigmatism,   Mixed astigmatism: A type of astigmatism that results in blurred distance and near vision. Light rays entering the eye are bent at different points, with one point focused in front of the retina and the other point focused behind the retina. Clear vision requires that all focus points be directly on the retina.   the symptoms of nearsightedness and farsightedness occur simultaneously. This combination of vision problems results in the overall inability to see images clearly.

After an eye doctor examines your eyes, he or she will write a prescription that annotates the severity of your condition. Because most people have some astigmatism, the typical prescription notation includes numbers indicating both the degree and direction of the error. See Understanding Your Prescription for more information.

Astigmatism: Treatment Options

The treatment for astigmatism depends on several factors, such as your age, activities, and occupation but is commonly treated with contact lenses or eye glasses.

See Eye Exams for information about how to get a prescription for corrective eyewear and Prevent Vision Problems for tips on strengthening your eyes.

To determine whether contact lenses or eyeglasses are better for you personally, read about glasses vs contact lenses.

LASIK Vision Correction

While eyeglasses and contact lenses certainly help correct certain vision problems, they are more comparable to bandages, meaning they help you to see better but are temporary fixes that don’t actually clear up the root of the problem the way surgical procedures can.

LASIK, the most widely performed and accepted form of laser eye surgery since it completed US clinical trials in 1991, can actually eliminate or reduce your need for eyeglasses or contact lenses by reshaping the cornea. To learn more, read about LASIK eye surgery or more customized options such as OptiLASIK® Laser Vision Correction, which further reduces the need for glasses or contacts and gives the kind of advanced procedure that provides a more ideal, natural eye shape.

Toric Astigmatism Lenses

Sometimes, surgery is necessary in fixing an astigmatic eye. Intraocular lenses (IOL)   Intraocular lens (IOL): An artificial lens made of plastic, silicone, or acrylic, which is designed to be implanted in the eye to improve its focus and correct vision problems related to cataracts.   used in correcting astigmatism during cataract surgery are called toric. One of the advanced technology toric lenses on the market today is made by Alcon and offers a more precise correction in vision. For more information, read more about AcrySof® IQ Toric IOLs here.

Click on LASIK for more information about this type of refractive eye procedure.

Next: Presbyopia



  1. American Academy of Ophthalmology Web site. Eye Health Statistics at a Glance. Accessed January 12, 2011.