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How Do I Know If I Have It?

People usually go to the doctor complaining of blurred vision or, in the case of children, when they've failed their annual vision exam at school.

The doctor may use one or more of these four tests to detect and measure your level of astigmatism.

The Vision Test. It's the simplest yet most important part of an eye exam. Using a standardized chart, patients read off the letters they can see from 20 feet away. If your vision is 20/20, this means you can see at 20 feet what a normal eye can see from 20 feet. If your vision is 20/80, this means you can only see at 20 feet what a normal eye should be able to see from 80 feet away.

Refraction. This test uses a lens machine (phoropterto hold corrective lenses in front of your eye.  The doctor looks inside a handheld device called a retinoscope to determine if any refractive error is present.  Then the eye doctor will offer you different choices in lenses through the phoropter to refine the correction until you can see the vision chart clearly.  After both eyes are measured your doctor will write a prescription for eyeglasses based on which corrective lenses worked for you.

Keratometry. This machine measures the curvature of your central cornea.  Corneas that have no astigmatism exhibit uniform, round curvature.  Corneas with astigmatism have an inconsistent curvature.  The keratometer determines the steepest and the flattest curves.  These measurements tell your doctor about your corneas' shape and focusing power.  The keratometer is also used to fit contact lenses and to monitor corneal curvature after eye surgery.

Corneal Topography. This advanced technology provides the most detailed information about the shape of a cornea.  The patient looks at a visual target while the device collects thousands of tiny measurements.  A computer then constructs a color map on the computer from the data.  This corneal map allows the doctor to see a three-dimensional picture of your cornea.  Such sophisticated measurements are important for planning refractive surgery and fitting contact lenses.

Astigmatism can be corrected with glasses, contact lenses, or surgery.

Eyeglass lenses are shaped to counteract the shape of the cornea that's causing blurred vision. Eyeglasses work well when the patient looks straight ahead.  But, depending on the specific correction, the glasses can make the floor appear to tilt.  Some doctors argue that people with very small amounts of astigmatism are best left untreated.  Patients with significant astigmatism usually adjust to their first pair of glasses within a week or so.  If things remain unclear ask your doctor to recheck the prescription and verify the correction in your new spectacles.

Specially designed contact lenses can also correct astigmatism. All contact lenses rotate when a person blinks. The lenses used for astigmatism — called "toric" lenses — are designed to return to the same position each time the wearer blinks. Thus, toric contact lenses compensate for any abnormal curvature in your cornea.

Laser eye surgery to correct astigmatism was approved by the FDA in 1997.  In this technique, the surgeon uses a laser to reshape the cornea so it can focus light rays better.  It's the only treatment that directly fixes the underlying problem causing astigmatism.

In laser surgery (commonly known as LASIK), a sterile mechanical devise (or another laser) creates a delicate flap in your cornea that is thinner than a grape skin.  Numbing eyedrops prevent the patient from feeling pain.  The surgeon lifts and sweeps back the flap with a tiny instrument.  The central portion of the deeper corneal layers is exposed for laser treatment.  Next, you will hear clicking noises as a laser precisely removes tiny amounts of your inner cornea.  The doctor then sweeps the flap back to its original position.  Finally, the doctor administers, anti-inflammatory, and antibiotic eye drops.  Once the doctor covers your eyes with transparent shields, you're ready to go home.

This surgery is costly, ranging from $700-$3,000 per eye.  Because cheaper eyeglasses can also fix the problem, LASIK is rarely covered by health insurance. It's considered elective surgery.

There are some downsides:

• The surgery may overcorrect or undercorrect your refractive error, requiring follow-up surgery
• You may see a glare around lights that impairs your vision at night
• You may have increased dryness of the eye
• You may still need to wear glasses, especially especially as you lose near-focusing power with age.

Astigmatic keratotomy, a modification of radial keratotomy, is another procedure used to correct astigmatism.  The surgeon performs tiny cuts into the cornea that are strategically on the steepest curves.  This allows light to focus more precisely on the retina.  This procedure is gradually being replaced by laser surgery.

There is no known way to prevent astigmatism.