Updated on 

May 3, 2022

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Astigmatism: Causes & Treatment

What Is Astigmatism?

Astigmatism (pronounced uh-stig'-muh-tiz-um) is an eye condition that causes blurred vision at all distances.

You can have it in one or both eyes. Astigmatism may also occur with other refractive disorders.

Myopic astigmatism is when you have both astigmatism and myopia (nearsightedness) in one eye.

Hyperopic astigmatism is when it occurs with hyperopia (farsightedness).

A normal eye focuses light directly on the retina. Refractive errors prevent the eye from correctly focusing light.

With astigmatism, the eye focuses light at the retina's front and/or back. This leads to blurry vision.

astigmatism eye defect

What Causes Astigmatism?

You need a spherical (round eye) to have a normal visual acuity. When the eye has an irregular shape, it causes astigmatism.

Astigmatism can be present at birth. But other factors may cause you to develop it later on.

Who is at risk for astigmatism?

Studies show these factors increase your risk for astigmatism:1,2

  • Older age
  • African American or Hispanic descent
  • Having a parent with astigmatism
  • Having a mother who smoked while pregnant
  • Having other refractive errors (e.g., myopia and hyperopia)

Some types of astigmatism occur as a complication of eye surgeries, such as cataract removal and LASIK surgery.

An eye disease, infection, or eye injury can also put you at risk. They can scar your cornea or change its shape.

Astigmatism affects 36.2% of Americans and is the most common refractive error in the U.S.3 It is not caused by squinting, reading in dim light, or watching the television up close.

Types of Astigmatism

You can have corneal or lenticular astigmatism, depending on whether the cornea or lens is affected:4

  • Corneal astigmatism. The surface of your eye (cornea) has an abnormal egg-shaped curve.
  • Lenticular astigmatism. The eye lens is misshaped.

It is also possible to have both types of astigmatism in one eye.

astigmatism sphere

Corneal astigmatism can be regular or irregular.

If the steepest and flattest parts of your cornea (called principal meridians) are perpendicular to each other and are 90 degrees apart, you have regular astigmatism.

But if the meridians are not evenly far apart, the cornea forms an uneven shape. This results in irregular astigmatism.

Irregular astigmatism typically develops from eye diseases, injuries, and infections that lead to corneal abrasion. However, it rarely occurs. Most people have regular astigmatism.

Symptoms of Astigmatism

Some people with astigmatism do not experience symptoms. Those who do may experience the following:5

  • Blurry vision when looking at near or far objects
  • Straining or squinting to see objects more clearly
  • Seeing glare or starbursts around lights
  • Headaches and eye discomfort
  • Difficulty seeing at night

Astigmatism symptoms can be harder to detect in younger children. They may not notice they have a vision problem, so they won't be able to report it.

If your child has frequent headaches or sudden changes in school performance, consider having them checked for signs of astigmatism.

Astigmatism Diagnosis

An eye doctor will need you to complete an eye exam. This includes reading a Snellen chart so they can assess your visual acuity.

They will also use tools to measure your vision, such as:

  • Phoropter. A series of lenses that checks your prescription. It helps the eye doctor figure out which lenses give you the clearest vision.
  • Keratometer. The machine measures the steepest and flattest areas of your cornea. Doctors use it to determine how your eyes focus light.
  • Autorefractor. The device shines light into your eye and then measures how it bounces off. It tells the eye doctor which lenses you need.
  • Corneal topographer. The imaging test accurately measures your cornea and creates a detailed map. Surgeons use the image to create custom-fit lenses and plan your eye surgery.

Can Astigmatism Be Treated?

Yes. Regular astigmatism is a treatable condition. Eye doctors can accurately measure it and prescribe appropriate treatment.

Irregular astigmatism is not as easy to treat. Doctors are still finding ways to measure and correct it. As such, most treatments only correct regular astigmatism.6

Some treatment options like orthokeratology and corrective lenses provide temporary solutions. They can only treat astigmatism for as long as you wear them.

Surgeries such as lens replacement, phakic implants, laser surgery offer more permanent solutions.

Here are the treatments for astigmatism:

Eyeglasses

Corrective lenses like glasses are commonly prescribed for astigmatism. When worn, they can focus light rays to your retina.

Eyeglasses that correct astigmatism are different from normal glasses. They have CYL (cylinder) and AXIS specifications which denote lens power and the rotation of astigmatism correction.

If you have a combination of astigmatism and other refractive errors, your doctor may recommend progressive lenses.

Contact lenses

Contacts are another standard treatment for astigmatism. Like eyeglasses, they bend light rays and focus them to your retina.

Doctors may prescribe disposable contacts, rigid contact lenses, or toric lenses that are specially designed for astigmatism.

You can choose contacts based on your budget and convenience. If you want to explore your options, check out our review of the Best Contacts for Astigmatism.

Orthokeratology (ortho-k)

Orthokeratology is a non-invasive lens correction therapy. It is often used to treat myopia. But it can also correct mild to moderate astigmatism.

The treatment lasts two weeks and involves wearing rigid gas permeable contact lenses. These lenses are designed to fit your eyes and gently reshape your cornea.

Once the cornea adjusts to a normal shape, the ophthalmologist will provide retainer lenses to help maintain it.

Lens Replacement Surgery

Also known as refractive lens exchange, it is an invasive surgical procedure that removes the misshaped eye lens. The natural lens is then replaced with a toric lens.

Lens replacement is recommended for:

  • Lenticular astigmatism
  • People at risk or already have cataracts

Phakic Intraocular Lenses (IOLs)

The treatment is an invasive surgery that inserts phakic lenses into your eye. But instead of replacing your eye's natural lens, it is either placed at the front or behind it.

Phakic lenses treat severe myopia and myopic astigmatism.

Laser Eye Surgery

Laser eye surgeries such as photorefractive keratectomy (PRK) and LASIK treat severe astigmatism. They can also treat myopia and hyperopia with slight astigmatism.

Not everyone is a candidate for LASIK or PRK. If you have a thin cornea, you may not be eligible for laser refractive surgery.

Astigmatism FAQs

How can you tell if you have astigmatism?

Blurred vision at various distances is a classic sign of astigmatism. However, it is best to consult an eye doctor. They can diagnose astigmatism using a combination of tools and tests that assess your eye health and how your cornea refracts light.

How is astigmatism measured?

Eye doctors use a keratometer to measure astigmatism in diopters (D). Mild astigmatism is 0.10 to 1.00 D. Moderate astigmatism is 1.00 to 2.00 D. Severe astigmatism is 2.00 to 4.00 D. Extreme astigmatism is over 4.00 D.

Can astigmatism go away?

No. Astigmatism does not go away on its own. That said, most available treatments are able to correct astigmatism. Some treatments provide more permanent solutions.

Does astigmatism get worse with age?

It depends. Astigmatism can stay the same or get worse, depending on your eye health. Studies show that it can worsen with age. It tends to be stable until the age of 50. By the time a person reaches 60 years old, it progresses.7

What degree of astigmatism requires glasses?

Moderate to extreme astigmatism that measures 1.50 to 4.00 diopters can be corrected with glasses. However, an eye doctor can help determine if eyeglasses are your best option, or if you should consider other treatments.

What are the best glasses for astigmatism?

Trivex, polycarbonate, and high-index lenses are best for severe cases of astigmatism.

Do I need specific contacts for astigmatism?

Yes. Disposable and rigid gas permeable lenses with a cylindrical (toric) design are recommended. They can correct astigmatism and other refractive errors.

7 Cited Research Articles
  1. "Astigmatism." University of Virginia Health.
  2. "Risk Factors for Astigmatism in a Population-Based Study of Children. The Multiethnic Pediatric Eye Disease and the Baltimore Pediatric Eye Disease Studies." Investigative Ophthalmology & Visual Science.
  3. "Prevalence of Refractive Error in the United States, 1999-2004." JAMA Network.
  4. "Astigmatism." Cleveland Clinic.
  5. "What Is Astigmatism?" American Academy of Ophthalmology.
  6. "Astigmatism." Encyclopedia of the Eye.
  7. "Does Astigmatism Get Worse With Age?" American Academy of Ophthalmology.
Melody Huang is an optometrist and freelance health writer. Through her writing, Dr. Huang enjoys educating patients on how to lead healthier and happier lives. She also has an interest in Eastern medicine practices and learning about integrative medicine. When she’s not working, Dr. Huang loves reviewing new skin care products, trying interesting food recipes, or hanging with her adopted cats.
https://www.visioncenter.org/author/melody/
Author: Dr. Melody Huang, O.D.  | UPDATED May 3, 2022
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The information provided on VisionCenter.org should not be used in place of actual information provided by a doctor or a specialist.

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