What does 20/20 vision mean? The numbers... not the fact it means you have "normal vision" And can they rate your vision higher than this? They always say my vision is "Normal" wearing my glasses,despite not being able to read the next to bottom line on an Eyechart fully, nor have a go at the bottom line. Can anyone explain? Without my Glasses I can just make out the 2nd line down!
Posts: 13306 | Location: 6 miles west of Wigan UK | Registered: 06-05-02
20/20 is the somewhat arbitrary normal. It means that you can see something 20 feet away from you as well as a "normal" person could see it at 20 feet (that is, you can distinguish between letters as well as they could).
20/40 vision would mean that, at 20 feet, you can only see as well as a normal person could from twice as far back from the eye chart (40ft).
You can have better than 20/20 vision. For example, 20/10 vision would mean that, at 20 feet, you could see as well as a normal person could if they were only 10 feet away from the eye chart.
Of course, they don't usually rate you by moving you further and further back. Rather, they use smaller and smaller text.
The first number is really just to tell you the standard being used, and the second is your vision relative to that standard. For example, some use 6 meters as the standard, making normal vision 6/6 (6 meters = 19.7 feet). So, on that scale, 20/40 would be 6/12 and 20/10 would be 6/3.
While this may not mean anything to Bedstor, it will to citizens of the US. Baseball Hall of Famer Ted Williams was said to have 20/10 vision. He was one of the very best hitters in the game, .and was also a fighter pilot in both WWII and the Korean War, giving up about 5 seasons of baseball to serve his country. I think he was in his 80s when he died, and I never remember seeing him with glasses.
I just remembered this: Williams, who was sought out by the best hitters for his advice even in his 70s, once said he could hear the different sounds various pitches made as they came in, and adjusted his swing accordingly.
Posts: 17187 | Location: Lincoln Place, Granite City, IL, USA | Registered: 06-03-02
