PLEASE HELP ME...can you help me with my questions..?!
Question: PLEASE HELP ME...can you help me with my questions..?
( can you please break this 3 sentence down for me to understand it in a easyier way. I am confuse with the 200 and all the feet meaning). Thank you for you time and may you be bless....
Answers:
Best Answer - Chosen by Voters
Your last sentence (first paragraph) is wrong...
it should read...
"So a legally blind person needs a distance of two feet to spot the (9mm) letters on a standard eye chart [that a person with 20/20 can see at] 20 feet away.
That is to say.. what ever a person with 20/20 vision can see at 20 feet, a legally blind person must move into 2ft from that object, to be able to see the same thing as the 20/20 person.
One way to undestand visual acuity is with distance...
it's easier to think of it as a factor of 10... 20/200 is 10x worse than 20/20. So what ever a 20/20 person sees, the 20/200 sees 10x worse... so they must move into a tenth of the distance... to see the same thing.
Another way of thinking about it size of the letter....
If a 20/20 person can read 9mm letter at 20 feet... then a 20/200 person can only read a 90mm letter at 20 feet (note I keep the distance the same, but the size of the letter increased).