What does it mean to have 20/20 vision?

How Eye Doctors Measure the Sharpness of Your Vision

If you stand 20 feet from an 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, what you can see clearly is the same as what the average person sees clearly. 

When measuring your visual acuity, the first number always refers to the distance you can read a line of an eye chart, and the second number refers to the distance the average person can read that same line. For example, 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. People with 20/40 or 20/100 vision can't see things in the distance as sharply as people with 20/20 vision can. 

 Schedule an appointment to get your vision tested at eyecarecenter today! 

Does 20/20 vision mean perfect vision? 

Unfortunately, having 20/20 vision doesn't give you the license to brag about having stellar eyesight. It just means that you can see as well as the average person who doesn't need to wear glasses or contact lenses. 

In fact, some people have better-than-20/20 vision. People with 20/15 vision can see things clearly from 20 feet away that the average person can't see clearly unless they stand 15 feet away. Similarly, an even smaller percentage of people have 20/10 vision and can see what the average person would have to stand 10 feet away to see. 

However, some people with 20/20 vision (or even 20/10 vision) may still need to wear glasses or contact lenses. That's because a 20/20 measurement needs to take into account things like whether 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. 

People with 20/20 Vision Still Have Eye Problems 

Some people have 20/20 vision because they can see well at a distance, but when they look at things close-up, those things appear blurry. This is called farsightedness, a refractive error that impacts the sharpness of your vision in certain circumstances. People with farsightedness may need to wear glasses to read, sew or do other close-up activities. 

There are also 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 contact lenses to improve their blurry vision. 

Finally, 20/20 vision can’t halt the effects of time on your vision. After the age of 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.