Vision Screening Online Training Program

Module 6 (continued): How is 20/20 associated with vision and what does it mean?
(C&TC: Usually performed by a nurse or medical assistant)

Q.)  What is visual acuity?

A.)  Visual acuity is defined as the sharpness or clearness of a person’s vision.

Q.)  What does having 20/20 vision mean and how do they get that number?

A.)  Visual acuity is written as a fraction:

Numerator: The number of feet at which screening is done (e.g., 10 feet, 20 feet)

Denominator: The lowest line on which the majority of the symbols are correctly identified.  (Size is indicated on the card or chart as 10, 15, 20, 30, 40, 50, 70, 100, and 200)


If ones vision is 20/70, it indicates that at twenty feet, the person can see what the normal eye can see at seventy feet. So, when a person has 20/20 vision they are able to read the 20-line on the chart from only 20 feet away.

For Instance: 20 (the best line the person being screened can see)
  40 (a person with normal vision could see the 20/40 line at 40 feet)

In recording Visual Acuity:
When screening is done at 20-foot distance, the results would be:
20 20 20, etc
20 30 40

When screening is done at a 10-foot distance, the results would be:
10 10 10, etc.
10 15 20


If a child has 20/15 eyesight, it means that they can see an object clearly at fifteen feet what a normal child could see at twenty feet?

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