{"id":7504,"date":"2020-08-23T12:18:08","date_gmt":"2020-08-23T12:18:08","guid":{"rendered":"https:\/\/www.optometrists.org\/?page_id=7504"},"modified":"2022-03-13T09:22:25","modified_gmt":"2022-03-13T09:22:25","slug":"what-is-a-visual-acuity-test","status":"publish","type":"page","link":"https:\/\/www.optometrists.org\/general-practice-optometry\/guide-to-eye-exams\/eye-exams\/what-is-a-visual-acuity-test\/","title":{"rendered":"What Is a Visual Acuity Test?"},"content":{"rendered":"

Your visual acuity, or clarity of vision, represents how well you are able to see objects or images at a given distance.\u00a0<\/b><\/h2>\n

Visual acuity is tested using a standardized chart during a routine eye exam<\/a>, but may also be performed in a doctor\u2019s office or school setting, during a vision screening<\/a>.<\/p>\n

What is the Snellen visual acuity test?<\/b><\/h2>\n

The Snellen test is a visual acuity chart that consists of 11 rows of capital letters, with one large letter at the top of the chart. As you move down the chart, the letters decrease in size, while the rows increase in length.<\/p>\n

The size of the letters are not random and are carefully measured and presented.<\/p>\n

There is one specific row of letters, usually close to the bottom of the chart, known as the 20\/20 line. This line has letters which a person with \u201820\/20\u2019 sight will be able to read from 20 feet away.<\/p>\n

When using the Snellen test in an eye doctor\u2019s office, the chart is generally projected onto the wall, approximately 20 feet away from the examination chair.<\/p>\n

In some cases, if the examination room is smaller in size, the Snellen chart will be posted behind the examination chair and viewed through a mirrored reflection across the room.<\/p>\n

How does the visual acuity test<\/b> work<\/b>?<\/h2>\n

During the visual acuity test, your eye doctor will instruct you to cover one eye while you read the letters aloud, starting from the top of the chart, until you can no longer see the letters clearly.<\/p>\n

Some eye doctors ask their patients to simply read the smallest line they are able to see, instead of starting from the top of the chart, as this saves a significant amount of time.<\/p>\n

After your visual acuity is determined for that eye, your second eye will be tested in the same way. The test is performed with and without eyeglasses, for the most accurate results. The results of the test are based on the line that you can correctly read most <\/i>of the letters.<\/p>\n

What is the random E test?<\/b><\/h2>\n

This test uses a \u201ctumbling E\u201d, a capital E that faces different directions, and decreases in size as you move down the chart. Eye doctors use this chart for young children or adults who are unable to identify letters.<\/p>\n

During the test, the patient will be asked to identify the direction in which the E is facing, up, down, left, or right, until they can no longer see the E clearly.<\/p>\n

Similar to the Snellen test, the results are based on the line that most of the E\u2019s can be identified correctly.<\/p>\n

What is 20\/20 vision?<\/b><\/h2>\n

Visual acuity is measured in a numeric fraction, such as 20\/20 or 20\/40. The top number represents the distance from the chart (20 feet), and the bottom number represents the distance at which the average person with normal eyesight can correctly read the same line.<\/p>\n

If your eye doctor tells you that you have 20\/20 vision, you can assume that you have normal visual acuity, and are able to see what most people can see when they stand 20 feet away from an object.<\/p>\n

What does it mean if I don\u2019t have 20\/20 vision?<\/b><\/h2>\n

If you don\u2019t have 20\/20 vision, you are not alone.<\/p>\n

Only about 35 percent of adults have 20\/20 vision without any corrective eyewear or surgery.\u00a0<\/b><\/p>\n

What is 20\/40 or 20\/60 vision?<\/b><\/h3>\n

If you have 20\/40 vision, it means that your vision is half as good as a person with 20\/20 vision. Meaning, you’re only able to clearly see the letters that are double<\/b> the size of the 20\/20 letters.<\/p>\n

This can be applied to other visual acuities as well:<\/p>\n

If you have 20\/60 vision, it means that you can only clearly see the letters that are 3x <\/b>the size of the 20\/20 letters.<\/p>\n

What is 20\/10 vision?<\/b><\/h3>\n

If you have 20\/10 vision on the other hand, it means that you have very sharp vision and can see better than a person with 20\/20 vision. Having 20\/10 vision means that you can see letters that are half<\/b> the size of the letters most people can see from 20 feet away..<\/p>\n

In most states, you are required to pass a visual acuity test with at least 20\/60 or better in order to obtain a driver\u2019s license.<\/p>\n

A visual acuity of 20\/200 or worse in the \u201cbetter\u201d eye, is generally considered the parameter for legal blindness.<\/p>\n

SEE RELATED:<\/b> Why Do Optometrists Use Eye Charts?\u00a0<\/a><\/p>\n

Schedule an eye exam<\/b><\/a> with an eye doctor near you if you feel your vision is not as good as it used to be.<\/b><\/p>\n\n\t

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