Impaired vision and blindness are not uncommon. About 3.4 million people in the U.S. are visually impaired. Vision is usually measured by visual acuity charts, and normal vision is expressed as 20/20.

What does 20/20 vision mean? When you visit your doctor or an eye care professional, you may be asked to read an eye chart. You may be told you have normal 20/20 vision. What does that really mean? An ...

IIIF provides researchers rich metadata and media viewing options for comparison of works across cultural heritage collections. Visit the IIIF page to learn more. Eye chart with an inscription that ...

Her eye chart tests showed improvement. It took a radical experiment to find out why her reality wasn’t matching up. By Lisa Sanders, M.D. See more of our coverage in your search results.Encuentra más ...