It’s 2020, the year of sight! But what does 20/20 vision actually mean?

According to the American Academy of Ophthalmology “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.” An eye chart measures visual acuity (the clarity or sharpness of vision) and is a part of a complete eye exam. The top number refers to your distance in feet from the eye chart. The bottom number is the distance at which a person with normal eyesight can read the same line. For example, if you have 20/40 vision it means when you are standing 20 feet away from the chart you can read letters that most people see when they are 40 feet away. A person can also have 20/15 vision, which is sharper than average. These people can see a line on an eye chart at 20 feet that the average person can only see when they are 15 feet away. Outside of the United States, vision is measured in meters and the standard is “6/6.” 

https://www.aao.org/eye-health/tips-prevention/what-does-20-20-vision-mean