20/20 vision

Herman Snellen, a Dutch ophthalmologist, designed the first eyechart, which measures visual acuity. Referred to as the SnellenChart, it was developed in 1862 and is still used today.He set the baseline of measurement at 20 feet, the approximatedistance at which light rays entering the eye are paralleland do not require our eyes to bend the rays to focus themupon the retina.Snellen set the standard of 20/20 vision to represent "normalsight," or what a person with normal vision could see at adistance of 20 feet.This means that a person with 20/40 vision must be 20 feet awayto read what he or she should be able to read at 40 feet; aperson with 20/85 vision must be 20 feet away to read what heor she should be able to read at 85 feet away, and so on.This standard does not measure visual acuity at close distances.Similar charts were devised with smaller letters to read atclose range for the measurement of near vision.A Snellen Chart is included in the Rebuild Your Vision programso you can measure your vision as it improves. I've alsoincluded a log for you to record your daily progress.To your vision - for life.