It’s common to hear “20/20 vision” when describing good eyesight, but you may not know what the term means. 20/20 vision is a measure of one’s visual acuity and indicates how clearly we see objects on an eye chart at 20 feet. The eye chart contains images, usually letters or pictures, of a very specific size gradually getting smaller near the bottom of the page.
If your visual acuity test determines you have 20/20 vision, it means you can clearly see what a person with normal vision should be able to see from 20 feet away. If you have 20/40 vision, you can see at 20 feet what a person with normal vision can see at 40 feet. If you’re one of the few people with 20/15 vision, you can see at 20 feet what a person with normal vision sees at 15 feet, and so on. In the U.S., you may be considered “legally blind” if your best-corrected vision (distance vision while wearing glasses or contacts) is 20/200 or worse. To get a driver’s license in the U.S., your best-corrected vision usually must be at 20/40 or better. If that requires glasses or contacts, it may say so on your driver’s license, and legally you may be required to wear them at all times when driving.