Almost one-third of Americans have what doctors call 20/20 vision. The term 20/20 vision comes from a system of measurement eye doctors use to test your visual acuity against the average person's. They determine this by having you stand 20 feet away from an eye chart and read aloud the letters that appear on different lines of the chart.
For example, if you stand 20 feet from a Snellen eye chart and read the line of letters that people with average vision can see clearly from that same distance, you have 20/20 vision. The numbers simply mean that from 20 feet away, what you can see clearly is the same as what the average person sees clearly.
When someone can't see things as sharply as someone with 20/20 vision, they may learn that they have 20/40 vision or 20/100 vision. That means the smallest letters they can clearly decipher from 20 feet away are the same as what an average person can clearly decipher from 40 or 100 feet away. There are many reasons why you might not have 20/20 vision, including refractive errors like being near or farsighted.
The best way to keep your vision healthy is to have regular eye exams and checkups with your eye doctor.
Many people think having 20/20 vision means you can see perfectly. In reality, it just means that you can see as well as the average person who doesn't need to wear glasses or contact lenses.
Some people actually have better-than-20/20 vision. People with 20/15 or 20/10 vision can see things clearly from 20 feet away that the average person can't see clearly unless they stand 15 feet away or 10 feet away respectively.
However, people with 20/20 vision or better may still need to wear glasses or contact lenses. That's because a 20/20 measurement needs to take into account things like if you can discern colors properly or how well your peripheral vision and depth perception work. A Snellen eye chart test also can't measure how well you can see close-up items or if the shape of your eye affects your ability to see clearly. All of these things can have a major impact on the quality of your vision.
People with 20/20 vision can be farsighted just like anyone else. These people may need to wear glasses to read, sew or do other close-up activities without nearby objects appearing too blurry.
Age also affects your vision. After 40, many people can't focus well on close-up items that they used to be able to see clearly. They may need to wear reading glasses due to age-related vision changes even with 20/20 vision.
Finally, there are people with 20/20 vision who have astigmatism or blurry vision as a result of an irregular eye shape. These people may also need to wear glasses or specialized contact lenses called toric lenses to improve blurry vision.
If you don’t have 20/20 vision naturally, there’s good news. About 75 percent of people who wear corrective lenses can achieve a 20/20 result by retaking the vision test with their glasses on or their contact lenses in.
Some people may not achieve 20/20 vision while wearing corrective lenses, but glasses or contacts can still help enhance their vision. Even if you can’t reach 20/20 vision, it's important to know how well you score. To safely operate a motor vehicle in Arizona, you are required to score 20/40 or better on a Snellen eye chart test in at least one eye. Otherwise, you might be restricted to a B Class license, meaning you need to wear your corrective lenses to drive. If you score significantly lower than that, you may not be able to get a driver's license. If you score 20/200 with corrective lenses, you're considered legally blind.
20/20 vision doesn't translate to "perfect" vision by any means, but it does denote strong visual acuity at a distance. A check-up with your eye doctor can help you determine if you have 20/20 vision and, if not, whether corrective lenses can help you reach it.