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By John Egan
What better year than 2020 to focus on 20/20 vision, the importance of regular eye exams and how to maintain overall eye health?
As Burt Dubow, OD, FAA, an All About Vision editorial advisory board member whose cellphone's last four digits are 2020, says, “2020 is an iconic number for all eye folks.
"Even though it is not the very best visual acuity, it is the standard most people use when referring to good vision,” he adds.
So, in this year focused on good vision, let’s answer some common questions about 20/20 vision, other levels of visual acuity and how less-than-good vision can be corrected to 20/20.
What is 20/20 vision?
Is 20/20 really “normal, good vision”? Technically, yes.
The American Optometric Association explains that 20/20 vision refers to someone’s visual acuity — the clarity or sharpness of vision — measured at a distance of 20 feet without vision correction (such as eyeglasses or contact lenses).
So, if you have 20/20 vision, you can see clearly at 20 feet what typically should be seen at that distance. But if you have 20/100 vision, you must be as close as 20 feet to see what a person with normal vision can see at a 100-foot distance.
Is 20/20 perfect vision?
While 20/20 vision is normal, it is not perfect vision.
There’s “more to eye care than 20/20 vision,” says Barbara Horn, president of the American Optometric Association.
Other factors, such as peripheral vision and depth perception, go into determining whether your vision is ideal.
The 20/20 mark is “simply a point of reference,” says Dr. Mark Wilkinson, clinical professor of ophthalmology and visual sciences at the University of Iowa Carver College of Medicine.
“It doesn’t speak to quality of vision, which is one of the things that people get confused about — quality versus quantity,” Wilkinson says.
For example, the 20/20 measurement gauges the quantity of your vision (the ability to recognize letters on an eye chart), while a contrast sensitivity test determines the quality (how well you’re able to discern between light and dark, or contrast).
How is 20/20 vision determined?
Eye care professionals traditionally test for 20/20 vision by having you look at letters on an eye chart. Most optometrists and ophthalmologists use what’s known as the Snellen chart, dating back to 1862.
Eleven rows of capital letters usually appear on the Snellen chart. The first line shows one large letter. Row by row, the number of letters increases while the size of the letters gradually decreases. An eye care professional tests each eye’s vision without eyeglasses or contact lenses.
What does 20/20 mean?
The first number when measuring visual acuity (such as 20) refers to the distance in feet that you stand from the chart, according to the American Academy of Ophthalmology.
The second number (such as 20) indicates the distance where someone with normal eyesight can read the same line that you read correctly.
In most cases, the first number stays at 20, while the second number can vary.
Can you cheat on your eye test?
In the past, eye charts were printed on paper, and the letters remained in the same order. Therefore, somebody potentially could memorize the sequence of the letters.
Today, eye care professionals increasingly rely on electronic charts that randomly switch the order of the letters, Wilkinson says. With computerized eye charts, “there’s no way people can cheat,” he says.
A traditional Snellen eye chart features the letters C, D, E, F, L, O, P, T and Z.
Is 20/20 vision common?
Only about 35% of adults have 20/20 vision without glasses, contact lenses or corrective surgery, according to the University of Iowa Hospitals & Clinics. Including those using corrective measures, about 75% of adults have 20/20 visual acuity.
The remaining 25% of adults don’t see too well.
What is 20/15 vision? What is 20/40 vision?
Some people can see at 20/15 without vision correction, which is better than 20/20, says James Chapman, assistant dean of clinical affairs at the University of the Incarnate Word Rosenberg School of Optometry in San Antonio, Texas. On rare occasions, someone can even see at 20/10.
Wilkinson notes that some people mistakenly believe that if their vision is 20/40, their vision is two times worse than 20/20. Actually, 20/40 means their vision is simply three lines worse on the eye chart (which is much better than two times worse), he explains.
If your vision is 20/1400, though, it’s 700 times worse than 20/20.
What is considered poor vision?
If your vision is worse than 20/20, when is it considered bad?
At 20/25, you probably won’t need glasses, contacts or other vision correction, Chapman says. Correcting your vision from 20/25 to 20/20 likely wouldn’t improve your vision performance or your quality of life, he notes.
“Why bother? It doesn’t do you any good,” Chapman says. “You go around with both eyes open at the same time, so what happens is, you’re going to see as good as your best-seeing eye.”
However, Wilkinson points out that a patient who’s at 20/25 might be disappointed if their vision stays at that point when it can be elevated to 20/15.
How can vision be corrected to 20/20?
If someone’s vision is worse than 20/20 — like 20/40 — eye care professionals characteristically aim to improve it to at least 20/20 through prescription glasses, contact lenses or corrective surgery, Chapman says.
For example, at 20/30, a patient might need vision correction, depending on his or her work or lifestyle, Chapman says.
For instance, a spreadsheet-adoring, number-crunching accountant whose vision is 20/30 might want sharper up-close vision than someone like a farmer does, Chapman says. Therefore, the accountant might ask for vision correction to at least 20/20.
“Different people have different demands for how clear their vision should be,” he says.
Can you have different visual acuity in each eye?
In some cases, the visual acuity of a person’s right eye might differ from the visual acuity of the left eye, he says. For instance, the right eye might be 20/50 and the left eye is 20/60. But in that situation, the difference in visual acuity between the two eyes is minimal.
“Ninety-nine percent of the time, the two eyes are identical and symmetrical, which means that they’re basically mirror images of each other,” Chapman says.
What about someone with 20/20 vision in one eye but 20/100 in the other? “That changes the whole ballgame,” he says.
While that person still might see as well as their best-vision eye (20/20), their depth perception might be off and vision correct might be called for, he says.
What is considered low vision? What is legal blindness?
Here are some common benchmarks for low vision and legal blindness:
Low vision, caused by diseases such as macular degeneration, glaucoma and diabetic retinopathy, is classified as 20/70 or worse in the better eye, and it can’t be improved with regular glasses, contacts, medicine or surgery, according to the American Federation for the Blind.
Most federal agencies and health care providers in the U.S. define “legal blindness” as 20/200 or worse.
Vision requirements for a driver’s license vary from state to state, with the minimum number for corrected vision often ranging from 20/40 to 20/60 for the best eye or both eyes.
Will you need glasses or contacts with 20/20 vision?
Under most circumstances, someone with 20/20 vision won’t require glasses, contact lenses or other vision correction, Chapman says. At that level, they enjoy enough vision clarity to carry out everyday tasks and activities “without having to worry about vision being an obstacle,” he says.
But people with 20/20 vision might need vision correction if they suffer headaches after staring at a computer much of the day or if they experience other vision problems.
“Just because you see 20/20 doesn’t mean your eyes are perfect and you don’t need glasses,” Chapman says.
WHEN WAS YOUR LAST EYE EXAM? Find an eye doctor near you and schedule an appointment.
Page published on Tuesday, December 31, 2019
FAQs
What line is 20 40 on the eye chart? ›
The third line is equivalent to 20/40, it is the driver's test line.
What's better 20/20 vision or 15 20 vision? ›Normal vision is considered 20/20 vision. This means you can see things at 20 feet that a person with normal vision can see at 20 feet. If you have 20/15 vision, you can see things at 20 feet that a person with normal vision can see at 15 feet. This means that 20/15 vision has greater acuity than 20/20 vision.
What vision is better 20 20 or 25 25? ›Is 25/25 vision better than 20/20? No. 25/25 means normal sharpness of vision, or visual acuity, at 25 feet just as 20/20 indicates normal vision at 20 feet.
What's a better vision 20 20 or 20 30? ›You may be familiar with 20/20 vision, but do you know what 20/30 vision means? 20/30 vision is a level of visual clarity and sharpness somewhat less than the 20/20 ideal, but many people with this level of nearsightedness function well without glasses.
Does 20 40 vision need glasses? ›A person with 20/40 vision sees things at 20 feet that most people who don't need vision correction can see at 40 feet. This means that they are nearsighted, but only slightly. A person with 20/40 vision may or may not need eyeglasses or contacts, and can discuss his or her options with a doctor.
Is 20 50 vision legally blind? ›If you're legally blind, your vision is 20/200 or less in your better eye or your field of vision is less than 20 degrees.
Is 20 40 vision bad? ›Is 20/40 Vision Bad? Although 20/40 vision is less acute than average, that doesn't mean you should think of it as “bad.” Someone with 20/40 vision just wouldn't be able to see clearly at quite as far of a distance as someone with “normal” vision.
Does 20 70 vision need glasses? ›20/30 to 20/60: This means you may have a small vision issue, but your vision is almost normal. It's unlikely you'll need to wear glasses all the time. 20/70 to 20/160: This suggests that you have a more pressing issue with your vision. You may or may not need to wear glasses all the time.
Which is better vision 20 20 or 20 25? ›While 20/20 vision is considered the standard, it's important to know what bad vision is. If you were to have a visual acuity of 20/25, you typically won't need glasses or other corrective lenses. Corrective lenses wouldn't change your vision much nor improve your quality of life.
Does 20 80 vision need glasses? ›As you can see, 20/80 eyesight is not good for reading or seeing things up close and would be very difficult to do so without corrective lenses or low vision devices.
How does 20 40 vision look like? ›
20/40 vision means you can only see as well as what a normal person can see at 40 feet away. You may notice some blurriness at this stage and may require some form of vision correction.
Do you need glasses for 20 15 vision? ›A person can have 20/15 vision, which is sharper than average. If you have 20/15 vision, you can see a line in the eye chart at 20 feet that the average person can only see when they are 15 feet away. The goal of glasses or contacts is to bring a person's vision to 20/20.
Is 20 30 vision bad? ›20/30 to 20/60, this is considered mild vision loss, or near-normal vision. 20/70 to 20/160, this is considered moderate visual impairment, or moderate low vision. 20/200 or worse, this is considered severe visual impairment, or severe low vision.
What does 20 25 vision look like? ›20/25 vision simply means that what you (first number) can see at 20 feet, someone with average (good) vision can see at 25 feet. It's therefore slightly below the average, because the average person can see it a little farther away.
What is normal eye vision range? ›20/20 vision is normal vision acuity (the clarity or sharpness of vision) measured at a distance of 20 feet. If you have 20/20 vision, you can see clearly at 20 feet what should normally be seen at a distance.
Is 20 40 vision good enough for driving? ›The American Academy of Ophthalmology reports that people in most states can drive without glasses or contacts with a 20/40 test result. You may not see road signs as clearly as someone with 20/20 vision, but you are still considered a safe driver with this score.
What does 20 60 vision look like? ›For example, if your vision is 20/20, it means that from 20 feet away, you can see the smallest letters that should be seen at 20 feet. If your vision is 20/60, this means that from 20 feet away you can only see letters that would normally be visible at 60 feet.
What does 20 50 vision look like on a prescription? ›A prescription of - 1.25 works out to roughly 20/50 vision, -1.50 to 20/60 and so on.
What does 20 70 vision look like? ›The ratio measurement of vision describes visual acuity, or the sharpness of vision, at 20 feet from an object. For example, having 20/70 vision means that you must be at 20 feet to see what a person with normal vision can see at 70 feet.
Is 20 400 vision a disability? ›20/200 to 20/400 is considered severe visual impairment, or severe low vision. 20/500 to 20/1,000 is considered profound visual impairment, or profound low vision. Less than 20/1,000 is considered near-total visual impairment, or near total blindness.
Can you drive with 20 25 vision? ›
For you to hold an unrestricted driver's license, most states require a 20/40 vision or better. Legal blindness is when your 'best-corrected' vision with glasses or contacts is 20/200 or worse. You are not legally blind if your vision is better than 20/200 when you wear glasses or contacts.
What is considered poor eyesight? ›20/30 to 20/60 vision in the better eye, even with correction glasses, is considered mild vision loss or mild low vision. 20/70 to 20/130 vision is moderate low vision. 20/200 to 20/400 is severe low vision.
What is perfect eye vision? ›What is 20/20 vision? The definition of 20/20 vision is the ability to see an object clearly from 20 feet away. Others with normal vision can also see an object clearly at that distance.
Can a person with 20 80 vision drive? ›Visual Acuity: All drivers are required to have the best possible vision. Minimum of 20/70 in either eye, or both eyes together may pass with or without corrective lenses, if vision cannot be improved; however if one eye is blind or 20/200 or worse, the other eye must be 20/40 or better.
Is 20 200 legally blind? ›Visual acuity less than 20/200 is considered legally blind, but to actually fit the definition, the person must not be able to attain 20/200 vision even with prescription eyewear. Many people who would be legally blind without eyewear can function well in everyday life with appropriate glasses or contact lenses.
Is 6 60 vision legally blind? ›Moderate – visual acuity worse than 6/18 to 6/60. Severe – visual acuity worse than 6/60 to 3/60. Blindness – visual acuity worse than 3/60.
What does it mean to have 30 20 vision? ›This means when you are 20 feet away from an object, you can comfortably see details that most people with normal vision can also see at 20 feet distance. If you have 20/30 vision, that means what you see comfortably at 20 feet, can be seen by a person with "normal" vision at 30 feet.
Is 20 60 considered legally blind? ›To drive a vehicle in the United States without corrective glasses, you must have a visual acuity of 20/40 or above. Visual acuity of 20/200 (or worse) qualifies someone as legally blind. Therefore with 20/60 vision, you will either need a visual aid to get your vision to 20/40 or your license will be restricted.
Is 20 100 legally blind? ›Under the new criteria, if a person's visual acuity is measured with one of the newer charts, and they cannot read any of the letters on the 20/100 line, they will qualify as legally blind, based on a visual acuity of 20/200 or less.
What is 20 80 and 20 40 vision? ›With 20/40 vision, a person can pass a driver's license test. With 20/80 vision, a person still might be able to read a large newspaper headline. With 20/200 vision, a person is considered legally blind.
Is 20 15 vision bad? ›
20/15 vision is actually better than 20/20. Someone with 20/15 vision can see objects at 20 feet away that someone with 20/20 can only see at 15 feet away. The higher the second number, the less clear and sharp you'll see objects at a distance.
What does 3 60 vision look like? ›This means you can see at 6 metres what someone with standard vision could see from 60 metres away. The figures 6 / 60 or 3 / 60 are how the result of a Snellen test are written. The first number given is the distance in metres from the chart you sit when you read it.
What vision do you need to drive? ›Anyone who applies for an original or renewal driver license must meet the department's visual acuity (vision) screening standard. The DMV's vision screening standard is: 20/40 with both eyes tested together, and. 20/40 in one eye and at least, 20/70 in the other eye.
What does 20 16 vision look like? ›If you have better vision than 20/20 for example 20/16 it means that you can see at twenty feet what an average person can only see at sixteen feet and of course the opposite if you are 20/40, for example, it means you have poorer vision than an average person; you see at twenty feet what they see at forty feet from ...
Who has the best eyesight in the world? ›Eagles are thought to have the best eyesight of all; their eyes are as many as eight times sharper than ours. We don't do too badly either. Our vision is four to seven times as sharp as those of cats and dogs and 100 times sharper than that of a mouse or fruit fly!
What is 20 200 vision like? ›Based on visual acuity testing, a person is considered legally blind when their best corrected vision is 20/200, which means they need to be at least 20 feet away to see something that a person with normal vision can see from 200 feet away.
What line on eye chart is 20 70? ›If the smallest print you can read is line 3 (T O Z) from 20 feet away while wearing your regular glasses or contact lenses, the doctor records your vision (or visual acuity) as 20/70 with best correction.
What line on the eye chart is considered legally blind? ›In order to be legally blind, you must have a visual acuity of 20/200. This means that even with glasses or contacts, you can only read the first letter at the top of the Snellen Chart, if that.
What are the lines on an eye chart? ›The Snellen eye chart contains several lines of block letters, the largest, a single letter, sits on the top row. The letters on each successive row below decreases in size. The standard Snellen eye chart only typically uses only the following letters: C, D, E, F, L, O, P, T, and Z.
What is a perfect vision score? ›What is “Perfect” Vision? While 20/20 vision is considered to be perfect, it's not actually what we think of as perfect. Many people, mostly children, have better than 20/20 vision. Healthy eyes can easily go down to the 20/15 level with some accuracy.
What does 20 20 vision mean? ›
The phrase 20/20 vision means normal vision, explains J. Kevin McKinney, MD. “A person with 20/20 vision can see what an average individual can see on an eye chart when they are standing 20 feet away,” says Dr.
How does 20 20 vision look like? ›20/20 vision refers to “normal” vision, not “perfect” vision. Visual acuity is a term that means clarity or sharpness of vision and that the objects you see are crisply outlined and not blurry. Calling normal vision “20/20 vision” is true for eye care professionals in the U.S., but not everywhere in the world.
What line is 20 20 on the eye chart? ›The 20/20 mark is the mark that a person with normal acuity can read at a distance of six metres. The line on the eye chart is the Eighth line, that's the one that marks 20/20 vision.
How to pass an eye exam? ›- 20/40 with both eyes tested together, and.
- 20/40 in one eye and at least, 20/70 in the other eye.
20/10 vision is thought to be the maximum visual acuity of human eyes without binoculars or other magnifying devices. Recent advances in optics have led to the creation of corrective lenses that can provide this ultra-sharp vision.