Studies have found that"normal" vision is being able to see a certain size line on the eye chart (the Snellen Chart) from 20 feet away. If you have 20/20 vision, you can see clearly at 20 feet what should normally be seen at that distance. If you have 20/40 vision, it means that you must be as close as 20 feet to see what a person with normal vision can see at 40 feet. So, the first number refers to the distance you stand from the chart, and the second number is the distance a person with normal vision could read the same line you correctly read – the larger the second number, the worse the vision.
20/20 does not necessarily mean perfect vision. Some people can see well at a distance, but are unable to bring closer objects into focus because of hyperopia (farsightedness) or presbyopia (loss of focusing ability). In order to diagnose any causes that may be affecting your ability to see well, we recommend scheduling a comprehensive eye examination at one of our Atlanta area Thomas Eye Group locations.