Updated on  May 3, 2024
4 min read

How Does an Astigmatism Test Work?

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If you have blurry or distorted vision at all distances, astigmatism may be the underlying problem.

An online astigmatism test can be a good starting point to identify a possible astigmatism. However, an at-home astigmatism test isn’t an accurate or precise way to diagnose astigmatism.

The only way to get an official diagnosis for astigmatism is to have your eyes checked by an eye care professional. This article explores what astigmatism is, its symptoms, and how to test for astigmatism. 

How to Test for Astigmatism

The best way to determine if you have astigmatism is to schedule an evaluation with a medical professional, such as an optometrist or ophthalmologist.

Professional Eye Exam

Your eye doctor will perform a comprehensive eye exam to test for astigmatism. They’ll examine your overall eye health and visual acuity (visual sharpness).

You may be asked to cover one eye and read letters on an eye chart. You may also undergo other exams with several different devices. 

How They Work

Your eye doctor may use the following tools during your eye exam:

  • A phoropter. This device helps the eye doctor to determine the correction needed to improve your vision. You will look through different lenses so your eye doctor can see which is most suitable for your vision.
  • An autorefractor. This device gives the eye doctor a starting point to refine your prescription. It shines light into the eye and measures how it changes when it returns from the back of the eye.
  • A keratometer. This device helps measure the curve of your cornea. Your eye doctor may also include a corneal topography to learn more about the corneal surface and its shape. 

Online Astigmatism Test

Another option to help determine if you have astigmatism is an online test. Multiple online tests are available and can serve as an initial means to identify a vision problem. 

Remember that while online tests are helpful, they’re not conclusive. Online testing relies on your judgment and cannot effectively diagnose astigmatism. To get a confirmed diagnosis of astigmatism, you’ll need to follow up with an eye care professional.

How They Work

The tests are simple. You will look at a display of shapes and lines while standing a certain distance from the monitor. During this test, you will have to cover your left and right eyes, alternating between both. 

What is Astigmatism?

Astigmatism is a common type of refractive error. A refractive error is when your eye cannot refract (bend) light properly onto the retina. Astigmatism affects about 36% of adults in the U.S.6

diagram showing eye with normal vision vs astigmatism

Astigmatism occurs when the curvature of the cornea or lens is irregular. The curvature may appear as a football or egg instead of a round ball. Because of this incorrect eye formation, you can find viewing objects difficult.

Many people with astigmatism have other refractive errors, such as myopia (nearsightedness) or hyperopia (farsightedness). All these conditions are treatable with corrective lenses or refractive eye surgery, such as LASIK.

What Are the Main Symptoms of Astigmatism?

Mild astigmatism may not cause noticeable symptoms. In more severe cases of astigmatism, you may have symptoms that include:

  • Blurry vision 
  • Eye strain
  • Headaches
  • Dry eyes
  • Squinting
  • Eye discomfort
  • Night glare
  • Light sensitivity

Some people may confuse astigmatism with amblyopia (lazy eye). These eye conditions are not the same. However, severe astigmatism can contribute to amblyopia. 

What Are the Levels of Astigmatism?

Ophthalmologists and optometrists measure astigmatisms in diopters. A perfect eye with no astigmatism will have 0 diopters. However, many people have between 0.5 to 0.75 diopters of astigmatism.5 

With eye prescriptions, there are two areas or numbers that refer to astigmatism:

  • Cylinder. Reflects how steep or irregular the curvature of your cornea is
  • Axis. Shows where the astigmatism is on the cornea; ranges from 0 to 180 degrees 

Treatment Options for Astigmatism

There are many ways to correct astigmatism. Treatment for astigmatism may include:

Astigmatism Glasses

Eyeglasses for people with astigmatism have a special cylindrical lens prescription. This means that specific parts of the lens boast additional power.

In many cases, a single-vision lens may work to provide clear vision at any distance. You may need bifocals or progressive lenses if you’re over 40 and have presbyopia

Contact Lenses

Contact lenses that treat astigmatism are called toric lenses. There are many types of toric lenses available.

Depending on your needs, you may benefit from soft or rigid gas-permeable (hard) contact lenses. Your optometrist or ophthalmologist will help you determine the best lens type for your eyes. 

Eye Surgery

Laser refractive surgery, such as LASIK, can treat astigmatism and reduce the need for eyeglasses and contact lenses. LASIK stands for laser in situ keratomileusis. It involves reshaping the cornea with a laser. 

However, not everyone is a good candidate for LASIK. If LASIK isn’t right for you, your eye specialist may recommend PRK or LASEK.


Astigmatism is a type of refractive error that results from irregular curvature of the eye. It can cause night glare and blurred vision at all distances.

An online astigmatism test can provide an idea of whether you have astigmatism. However, seeing an eye specialist for an accurate diagnosis and treatment is necessary.

Updated on  May 3, 2024
6 sources cited
Updated on  May 3, 2024
  1. Astigmatism.” Mayo Clinic, 2021.

  2. Astigmatism.” American Optometric Association.

  3. Astigmatism.” Harvard Health Publishing, 2019.

  4. Boyd, K. “What is astigmatism? Symptoms, Causes, Diagnosis, Treatment.” American Academy of Ophthalmology, 2022.

  5. Vimont, C., and Turbert, D. “What Do Astigmatism Measurements Mean?” American Academy of Ophthalmology, 2021.

  6. Vitale et al. “Prevalence of Refractive Error in the United States, 1999-2004.” Archives of Ophthalmology, 2008.

The information provided on VisionCenter.org should not be used in place of actual information provided by a doctor or a specialist.