Refractive Errors: What Is Astigmatism?

08 Dec Refractive Errors: What Is Astigmatism?

You may have been told that you are astigmatic. You may also still find yourself wondering, what is astigmatism, exactly? Astigmatism is a condition that results when either the cornea (the clear outer layer of your eye) or lens has some distortion in its normally smooth, curved surface. The ideal cornea is rounded like a basketball, with an even curvature in all directions. If you have astigmatism, the corneal surface of your eye is likely to slope unevenly and take on more of an egg or football shape, according to EyeSmart.

When this happens, the light entering your eye is scattered by the uneven surface it encounters and is unable to converge at a singular point on the retina. Instead, the light rays come to a focus at multiple points both in front of and beyond your retina, and this results in blurriness or distortion that affects both your near and far vision.

What Is Astigmatism Like Compared to Other Refractive Errors?

Astigmatism is a called a refractive error because there is a failure to refract the light precisely onto the light-sensitive surface of the retina and create a sharp image. It often occurs alongside other refractive errors such as nearsightedness and farsightedness. These conditions are due to distortions in the shape of the eyeball (either too long or too short) rather than distortions in the corneal or lens surfaces.

What Is Astigmatism Caused By?

The specific cause of astigmatism is unknown, but EyeSmart states that most people are born with at least a small degree of it. Those who are diagnosed with astigmatism as a child may find that it either worsens or improves as they get older, and individuals who have a more rare condition called keratoconus may experience higher degrees of astigmatism due to a progressive weakening of their corneas. Keratoconus can often prevent patients from being good candidates for LAISK correction. Your surgeon can advise you if this is the case with your eyes.

How Is Astigmatism Diagnosed?

You may have some degree of astigmatism if you experience a blurriness or distortion of vision at all distances, eyestrain or frequent headaches. Astigmatism is best diagnosed by a comprehensive eye exam performed by an eye-care professional. During the exam, the curvature of your eye can be measured with a keratometer. Sophisticated corneal mapping technology in an instrument such as the Pentacam also provides precise measurements about the structure and topography of your cornea.

How Is Astigmatism Treated?

Most mild or moderate cases of astigmatism can be treated simply with glasses or contact lenses, which will offset any corneal distortion. Previously, only hard contact lenses were used to treat astigmatism, but soft toric lenses are now available for this.

Glasses can move on your face and contact lenses can rotate in your eye changing the correction. Having the astigmatism treated with LASIK can provide far better vision than glasses or contacts because the correction does not move. Surgical vision-correction procedures, such as LASIK, can address multiple types of refractive errors, including astigmatism, by reshaping the surface of the cornea with a highly focused laser beam.

Would you like to talk to someone here at Woodhams about astigmatism? Enter your information below and one of our patient care advocates will reach out to you or you can call us at 770-394-4000.