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A member asked:
What are the differences between an eye chart that starts with 20/200 and another that starts with 70ft-21?
A doctor has provided 1 answer
Letter size: The snellen visual acuity (the 20/20 notation) refers to seeing certain size letters at certain distances. The sizes are standardized for the viewing distance which is traditionally 20 feet.
Answered 11/17/2016
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