What is 20/20 Vision? - Page 4

Eye Chart -- Young Children

If this line is the smallest line of letters a person can correctly identify at the normal testing distance, he or she has "20/40" vision--this is the smallest line of letters they can see at 20 feet, but a person with normal vision can correctly identify these letters at a distance of 40 feet. So the larger letters on the Snellen chart are designated with visual acuity fractions that have a larger second (bottom) number, which is the maximum viewing distance from which a person with normal vision can correctly identify the letters on that line of the chart.