What is 20/20 vision?
20/20 is a measure of someone’s distance vision. It is a way for us to try to standardized patients vision so we can better study vision, compare one person to another, and see how are treatments may or may not be working.
20/20 vision refers to someone’s sharpness of vision measured at a distance of 20 feet without eyeglasses or contact lenses.
So, if you have 20/20 vision, you can see clearly at 20 feet what typically should be seen at that distance by a person with “normal” vision. On the other hand, if you have 20/40 vision- this means that while you have to stand 20 feet away from the eye chart to see the letters, a person with “normal” vision could stand 40 feet away and still see it as well as you do.
The first number when measuring visual acuity (the first part of 20/20) refers to the distance in feet that you stand from the eye chart.
The second number (the second part of 20/20) indicates the distance where someone with normal eyesight can stand and still read the same line that you read correctly from 20 feet away.
In measuring vision, the first number (20) always stays the same, while the second number gets bigger the worse a person’s vision is.
While 20/20 vision is normal, it is not perfect vision. 20/20 doesn’t speak to the quality of vision only the quantity. A person may have 20/20 vision and still complain of blur. This is because simple visual acuity doesn’t take into account quality measures such as color, contrast, depth, and peripheral vision.
Only about 1 out of 3 adults have 20/20 vision without glasses or contact lenses. 2 out 3 adults require glasses or contact lenses. But even with glasses and contact lenses in place only 75% of people are able to see 20/20. The remaining 25% of adults don’t see too well even with contacts or glasses due to various eye diseases. This is why everyone needs a routine eye exam to make sure that they are not unknowingly slowly losing vision.