What is 20/20 Vision? - Page 2

Eye Chart -- for Kids and Non-spelling Languages

The traditional Snellen eye chart has a single large block letter (usually an "E") on the top of the chart, and 10 subsequent lines of progressively smaller block letters. Each line has more letters than the previous line to keep spacing between the letters relatively uniform. By experimentation, Snellen determined the smallest letters a person with "normal" vision could consistently identify correctly. This became the 20/20 line on the chart. In other words, if you can correctly identify letters of this size on the eye chart (but none smaller) from a testing distance of 20 feet, you have normal (or "20/20") vision.