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A fraction or a decimal describing how well someone sees.
Also known as: Snellen fraction, 20/20 vision
Visual acuity is written as a fraction — 6/6 in metres or 20/20 in feet — comparing what the person sees at a distance with what a standard observer sees. The two are the same measurement in different units, and a smaller second number means better vision.
States how well a person sees, as a ratio of the test distance to the distance at which a standard observer could read the same line.
Contexts: Medicine
Is written as 6/6 in metres and 20/20 in feet for the same normal result, which is why the two figures are not different standards.
Contexts: Medicine
Improves as the second number falls, so 6/4 is better than normal and 6/60 is severely reduced.
Contexts: Medicine
Two numerals separated by a slash, printed in a row on a sight test record.