Results from smartphone-based Snellen charts, which are eye charts used to measure visual acuity, are not consistent with results from standard Snellen visual acuity chart tests, according to a study ...
Impaired vision and blindness are common. About 3.4 million people in the US are blind or visually impaired. Vision is usually measured by visual acuity charts, and normal vision is expressed as 20/20 ...
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