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A member asked:
How do they test on an eye reading chart; what do the numbers mean?
2 doctors weighed in across 2 answers
Eye chart: They test visual acuity to determine type of glasses or contacts you might need.
Answered 9/14/2016
5.8k views
Visual acuity: The numbers 20/20, 20/25, etc. Are a measurement of visual acuity. It has been found that a normal human eye should be able to discriminate a spatial pattern separated by a visual angle of 1 minute of arc. This translates to a 20/20 letter being 8.87 mm high at 20 feet. If that image can be seen, the vision is 20/20. Larger letters are in proportion. The "20" on top is the testing distance.
Answered 4/6/2013
5.2k views
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