What Is Astigmatism?

Table of Contents
View All
Table of Contents

Astigmatism is a vision problem that causes objects to appear distorted and blurry. It was termed a condition in 1802 when physicist and physician Thomas Young discovered his own astigmatism by finding "different orientations cannot be brought to a focus in the same plane when one set of lines are sharply focused the other appear blurred, and vice versa." It often affects both distance and near vision. It is the most common vision problem and it may occur with nearsightedness and farsightedness.

Annual eye exam by optometrist
AMR Image/E+/Getty Images

Signs and Symptoms

Astigmatism usually causes vision to be blurry at distance as well as near. Astigmatism usually causes vision to be blurry at a distance and near. In addition, patients with astigmatism often have reading problems proven by a 2016 study conducted by the University of Arizona. The study, published in Optometry and Vision Science, showed children with bilateral astigmatism had issues with oral reading fluency.

Causes

Astigmatism is caused by the cornea having an oblong shape, like a football, instead of a spherical shape, like a basketball.

A cornea with astigmatism has two curves, one flat curve and one that is steep. Light is then focused at two points instead of one. One point of focus may be in front of the retina and the other behind.

This causes images to appear distorted in addition to appearing blurry. Astigmatism may also be caused by an irregularly shaped crystalline lens. This condition is termed lenticular astigmatism.

Diagnosis

Astigmatism is diagnosed by a manual keratometer, an instrument used to measure the curvature of the cornea. A keratometer is often used in a basic eye examination.

The diagnosis also may be made by using a corneal topographer. A corneal topographer is an instrument that gives a color-coded map, similar to a topographical map of mountains. Steeper areas are indicated in red and flatter areas in blue.

A wavefront aberrometer will also give the eye doctor much more precise information about astigmatism.

Treatments

Astigmatism corrects with glasses, contact lenses, or surgery. The American Academy of Opthalmology reports that most people range between 0.5 to 0.75 diopters of astigmatism; however, those measuring 1.5 or more need eyeglasses and contacts.

  • Glasses: Glasses work well with patients with regular astigmatism to return to 20/20; however, glasses may not do the job if the astigmatism is too high.
  • Contact lenses: Though glasses and soft contacts can correct regular astigmatism, they cannot fix irregular astigmatism; however, customized contacts can work, restoring vision to 20/20.
  • Surgery: Astigmatic Keratotomy (AK) AK, a degree corneal relaxing incision surgery that flattens the cornea's steep curves that cause astigmatism, is one type of surgical procedure.

LASIK Surgery and Astigmatism

If you have astigmatism, don't think you can't have LASIK eye surgery. It is a possibility for most. LASIK surgery is used for correcting refractive errors such as astigmatism, myopia, and hyperopia. Many people with astigmatism have found LASIK eye surgery to be a safe and effective method of vision correction since the U.S. Federal Drug Administration's first approval of laser device types in 1999. There are more than 30 different FDA-approved lasers for surgery.

Other Surgeries for Astigmatism

While most who have astigmatism can have LASIK, some people have too much astigmatism for the laser to correct. Other corrective surgeries to address astigmatism include photorefractive keratectomy (PRK), radial keratotomy (RK), automated lamellar keratoplasty (ALK), laser thermal keratoplasty (LTK), conductive keratoplasty (CK), or intracorneal ring (Intacs). If you have eye problems, including nearsighted or farsighted issues caused by astigmatism, discuss the following options with your optometrist to determine the best choice for your vision. 

Was this page helpful?
16 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Grzybowski A, Kanclerz P. Beginnings of astigmatism understanding and management in the 19th century. Eye & Contact Lens: Science & Clinical Practice. 2018;44(1):S22-S29. doi. 10.1097/ICL.0000000000000449.

  2. Portraits of Neuroscientists. Thomas Young.

  3. American Optometric Association. Astigmatism.

  4. Harvey EM, Miller JM, Twelker JD, Davis AL. Reading fluency in school-aged children with bilateral astigmatism. Optometry and Vision Science. 2016;93(2):118-125. doi. 10.1097/OPX.0000000000000779.

  5. MyHealth.Alberta.ca. Astigmatism. Care Instructions.

  6. Dean McGee Eye Institute. What is Astigmatism and How Can it Be Corrected?

  7. Yee JW. Correcting lenticular astigmatism by reinstating the correct neuromuscular message. Medical Hypotheses. 2013;81(1):36-40. doi. 10.1016/j.mehy.2013.03.041.

  8. Optometry Times. Why keratometry is important.

  9. Opthalmology Web. Wavefront Aberrometry.

  10. Cleveland Clinic. Astigmatism.

  11. The American Academy of Opthalmology. What Do Astigmatism Measurements Mean?

  12. American Academy of Opthalmology. Can glasses fully correct my astigmatism?

  13. VisionCenter.org. Astigmatic Keratotomy (AK).

  14. University of Rochester Medical Center. Types of Eye Surgery for Refractive Errors.

  15. U.S. Federal Drug Administration. List of FDA-Approved Lasers for LASIK.

  16. Stanford's Children Hosptial. Types of Eye Surgery for Refractive Errors.