Definition: Visual acuity refers to the quality of a person's sight. It is typically expressed as a ratio, as in 20/20. This ratio enables ophthalmologists to compare a person's vision to that of average people. The first number represents what the examinee sees at a distance of twenty feet. The second number represents how far most people can be to see the the same sized object.
Students with a visual acuity of 20/20 can clearly see what most others can see at a distance of twenty feet. Weaker visual acuities are expressed as 20/ followed by gradually increasing numbers. For example, a student with a visual acuity of 20/50 indicates he must be within twenty feet to see what others can see clearly at fifty feet.
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Examples:
Joe's visual acuity is 20/60, so he does not see as clearly as most of the other students.
