What Does 20/20 Vision Mean? How Is It Measured?

September 23, 2024

Roughly one-third of American adults have 20/20 vision without corrective lenses. Though some use the phrase "20/20 vision" as a general term for excellent eyesight, it actually has a concrete definition. "20/20 vision" is a term used to express visual acuity and indicates normal eyesight.

But what about 20/10 vision or 20/40 vision? What do all of these strange terms mean?

Keep reading to learn more!

Key Takeaways

20/20 is a term that refers to visual acuity. It refers to the ability to see objects 20 feet away that should be seen 20 feet away.
However, 20/20 vision does not refer to other factors like depth perception, peripheral vision, or color blindness.
20/10 vision or 20/40 vision are other terms that refer to visual acuity.

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What Is 20/20 Vision?

The term "20/20 vision" refers to visual acuity. Visual acuity is the clarity or sharpness of vision at a certain distance. However, visual acuity doesn't consider other things like peripheral vision, color blindness, or depth perception, so it does not paint a holistic picture of someone's eyesight or ocular abilities.

20/20 vision refers to the ability to read letters or numbers at a standard distance. 20/20 vision, specifically, is the ability to see an object that is 20 feet away.\

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Photo Credit: @carolineabram.paris

Contrary to popular belief, 20/20 vision does not mean "perfect" vision. Rather, it simply indicates normal vision.

20/20 vision can be determined via a visual acuity test. This test is conducted at most comprehensive eye exams by a licensed optometrist. Someone can be prescribed 20/20 vision if they are able to see objects, such as letters or numbers, that are 20 feet away, which should normally be seen at 20 feet away.

Most comprehensive eye exams also involve a vision test for peripheral awareness, eye coordination, depth perception, color vision, and focusing ability. Your optometrist will also check you for signs of eye disease or other abnormalities at your next visit.

The Snellen Eye Chart

The most common method of measuring visual acuity is by using the Snellen eye chart. The Snellen eye chart displays letters in progressively smaller sizes line by line, typically starting with the letter "E." There are usually 11 lines of block letters, and line 8 is considered 20/20 visual acuity.

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The Snellen eye chart is often used in an optically folded exam room, which utilizes mirrors to create the illusion of a 20-foot-long room. This is because most eye clinics do not have exam rooms that are 20 feet long.

Variants of 20/20 Vision

In addition to 20/20 vision, you may have heard of 20/10 vision or 20/40 vision. 20/10 vision or 20/40 vision refers to visual acuity that is not considered normal. It is possible to see worse or better than 20/20 vision.

For example, 20/10 vision means that you can see objects that are 20 feet away that the average person sees when 10 feet away. 20/40 vision means that you can see objects that are 20 feet away that the average person sees when 40 feet away.

Visual acuity can be defined by two numbers, hence the XX/XX layout. The first number is the distance away from the Snellen chart - in the United States, this is always 20 feet. The second number is the distance from which someone with normal vision can read the same line on the Snellen chart.

Keep in mind that visual acuity can be measured differently in different countries. For example, in the United Kingdom, normal vision is 6/6 instead of 20/20, as they measure visual acuity from 6 meters away instead of 20 feet away.

Final Thoughts

Though 20/20 vision may be considered normal visual acuity, it's not overly common to have 20/20 vision without corrective lenses. In fact, only one-third of all adults have 20/20 vision without corrective lenses. Luckily, it's easy to get prescription glasses or contact lenses that offer vision correction.

At Oculus Eyecare, we carry a carefully curated collection of luxury frames and designer eyewear that make it easy to see and be seen in a new way. Our eye care professionals and experienced opticians will help you discover the perfect pair of glasses that boost your confidence, enhance your personal style, and fit comfortably.

Bonus: What Should People Avoid Doing After Eye Dilation?

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Photo Credit: @jacquesmariemage

Frequently Asked Questions

How common is 20/20 vision?

About 35% of all adults have 20/20 vision without corrective lenses like contacts or eyeglasses.

What does 20/15 vision mean?

20/15 vision is better than normal vision. 20/15 vision means you can see objects that are 20 feet away that the average person sees when 15 feet away.

What does 20/80 vision mean?

20/80 vision means that you can see objects that are 20 feet away that the average person sees when 80 feet away.

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Oculus Eyecare is Seattle’s premier optometry practice and optical boutique for those looking to see and be seen in a new way. Located in South Lake Union on Denny Way, Oculus Eyecare offers comprehensive eye care services and exams for individuals and families in Seattle. Click here to schedule an appointment or a personal styling session. To stay connected and learn more, follow us on Facebook, Instagram, and X/Twitter.