20/20 vision is a term used to express normal visual acuity (the clarity or sharpness of vision) measured at a distance of 20 feet. … If you have 20/100 vision, it means that you must be as close as 20 feet to see what a person with normal vision can see at 100 feet.
An eye chart measures visual acuity, which is the clearness or sharpness of vision. The top number is your distance in feet from the chart. The bottom number is the distance at which a person with normal eyesight can read the same line.
The goal of glasses and contact lenses is to bring a persons vision up to 20/20.
But 20/20 vision is not perfect 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 visual acuity test is just one aspect of the typical eye exam. Optometrist also test for vision skills such as:
- Peripheral awareness
- Eye coordination
- Depth perception
- Ability to focus
- Color vision