According to How Stuff Works, 20/20 vision is the ability to see what a normal person can see from 20 feet away.
A person with 20/13 vision is above average because he can see at 20 feet what the average person can see at 13 feet.
20/20 is the standard for human eyesight, according to How Stuff Works. However, as the second number in this fraction increases, so does a person’s visual acuity. For instance, a person with a measured vision of 20/200 is determined to be legally blind. However, the lower the second number, the better the individual’s vision. A person with 20/10 vision would have exceptional eyesight.
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