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 ...

Good vision is a characteristic that is nice to have. Unfortunately, only 35% of adults have 20/20 vision without the use of glasses, contacts, or vision-correcting surgery. Though many of us do not ...