Astigmatismis a common refractive error that happens when parts of the eye are irregularly shaped, preventing light from focusing properly on theretina. As a result, people with this condition complain of blurred and distorted vision. This refractive error occurs in about one in three people and may occur in combination withnear-or farsightedness.
Getting a comprehensiveeye examis the best way to diagnose astigmatism. An optometrist or ophthalmologist will perform a few tests to see how the eyes focus light and the power of any corrective lenses needed to improve vision.Astigmatism tests can also be found online, but an eye doctor’s exam is needed for a precise diagnosis.
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What Is Astigmatism?
Astigmatism occurs when thecornea(a transparent layer in front of the pupil that focuses light into the eye) orlens(sits behind the pupil and helps light focus onto the retina) has an irregular shape. While a normal cornea has a spherical shape, the area in people with astigmatism will be oval-shaped.
In an eye without astigmatism, light bends (refraction) when entering the eye and goes through two different parts: first the cornea and then the lens. When either of them has an abnormal shape, the light will scatter instead of focus properly on the retina, which is responsible for sending lights as electrical impulses to the brain. As a result, the images at any distance will become blurry.
Symptoms of astigmatism include:
2:16Click Play to Learn All About Astigmatism
2:16
Click Play to Learn All About Astigmatism
The cause of astigmatism is unknown. People are born with astigmatism, but it may not be noticed until a child begins to attend school or learns to read.Some people may develop the condition as a child or young adult, or after an eye injury or surgery.
How Do Doctors Test for Astigmatism?
An optometrist or ophthalmologist will check your eyes with a few tests during an eye exam:
Can I Have Astigmatism in Both Eyes?
What Do Test Results Mean?
Astigmatism is measured in units of diopters. A perfect eye will have 0 diopters, but most people have between 0.5 to 0.75 diopters of astigmatism.Patients will only need glasses or contact lenses if the measurement is 1.5 diopters or more.
The last two numbers in your prescription refer to astigmatism:
Are Online Tests Reliable?
A number of online tests can help people check if they have astigmatism. They usually display shapes and lines and ask the test taker to stand a certain length away from the monitor. You will alternate covering your left and right eyes during these tests.
Online tests are not a replacement for an appointment with an optometrist or ophthalmologist. A conventional eye exam will measure the astigmatism level and find other complications, such as myopia and hypertropia. A specialist will also discuss the best way to treat the problem.
A Word From Verywell
Astigmatism is one of the most common eye problems, and many people may not even notice they have the condition when the symptoms are mild. For this reason, it’s important to have your eyes checked on a regular basis to catch the condition early. If you notice astigmatism symptoms, you can use an online test to check your vision. However, you should still visit your eye doctor for a proper evaluation afterward. They can tell you definitively whether you have the condition and recommend the appropriate treatment.
The treatments for astigmatism are often affordable, including eyeglasses and contact lenses. People who want to fix it permanently can also discuss the possibility of getting surgical treatment with their doctor.
Living With Astigmatism
8 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.American Academy of Ophthalmology.Eye Health Statistics.American Optometric Association.Astigmatism.Harvard Health Publishing.Astigmatism.National Eye Institute.Astigmatism.MedlinePlus.Visual acuity test.Read SA, Vincent SJ, Collins MJ.The visual and functional impacts of astigmatism and its clinical management.Ophthalmic Physiol Opt. 2014 May;34(3):267-94. doi: 10.1111/opo.12128American Academy of Ophthalmology.What Do Astigmatism Measurements Mean?American Academy of Ophthalmology.How to Read an Eyeglasses Prescription.Additional ReadingAmerican Academy of Ophthalmology.Eye Health Statistics.American Optometric Association.Astigmatism.American Academy of Ophthalmology.What Do Astigmatism Measurements Mean?American Academy of Ophthalmology.How to Read an Eyeglasses Prescription.Harvard Health Publishing.Astigmatism.
8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.American Academy of Ophthalmology.Eye Health Statistics.American Optometric Association.Astigmatism.Harvard Health Publishing.Astigmatism.National Eye Institute.Astigmatism.MedlinePlus.Visual acuity test.Read SA, Vincent SJ, Collins MJ.The visual and functional impacts of astigmatism and its clinical management.Ophthalmic Physiol Opt. 2014 May;34(3):267-94. doi: 10.1111/opo.12128American Academy of Ophthalmology.What Do Astigmatism Measurements Mean?American Academy of Ophthalmology.How to Read an Eyeglasses Prescription.Additional ReadingAmerican Academy of Ophthalmology.Eye Health Statistics.American Optometric Association.Astigmatism.American Academy of Ophthalmology.What Do Astigmatism Measurements Mean?American Academy of Ophthalmology.How to Read an Eyeglasses Prescription.Harvard Health Publishing.Astigmatism.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
American Academy of Ophthalmology.Eye Health Statistics.American Optometric Association.Astigmatism.Harvard Health Publishing.Astigmatism.National Eye Institute.Astigmatism.MedlinePlus.Visual acuity test.Read SA, Vincent SJ, Collins MJ.The visual and functional impacts of astigmatism and its clinical management.Ophthalmic Physiol Opt. 2014 May;34(3):267-94. doi: 10.1111/opo.12128American Academy of Ophthalmology.What Do Astigmatism Measurements Mean?American Academy of Ophthalmology.How to Read an Eyeglasses Prescription.
American Academy of Ophthalmology.Eye Health Statistics.
American Optometric Association.Astigmatism.
Harvard Health Publishing.Astigmatism.
National Eye Institute.Astigmatism.
MedlinePlus.Visual acuity test.
Read SA, Vincent SJ, Collins MJ.The visual and functional impacts of astigmatism and its clinical management.Ophthalmic Physiol Opt. 2014 May;34(3):267-94. doi: 10.1111/opo.12128
American Academy of Ophthalmology.What Do Astigmatism Measurements Mean?
American Academy of Ophthalmology.How to Read an Eyeglasses Prescription.
American Academy of Ophthalmology.Eye Health Statistics.American Optometric Association.Astigmatism.American Academy of Ophthalmology.What Do Astigmatism Measurements Mean?American Academy of Ophthalmology.How to Read an Eyeglasses Prescription.Harvard Health Publishing.Astigmatism.
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