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What are the differences between an eye chart that starts with 20/200 and another that starts with 70ft-21?

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Dr. Tim Conrad
Ophthalmology

In brief: 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.

In brief: 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.
Dr. Tim Conrad
Dr. Tim Conrad
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