What Do The Numbers Mean On Your Contact Lense Rx?

Can any one explain what the numbers on your prescription?
I know that 20/20 is perfect vision, but when the numbers are negative numbers, explain what it means and when your eyes are really really bad, meaning that you can’t see your own hand if you hold it straight out in front of you (without your contacts or glasses of course) what would your numbers be to be considered legally blind?
when I say that you can’t see it I don’t mean that you can’t see anything, but if you had a paper in your hand, you probably couldn’t see what was written on it even if it was the size of the biggest letter on the eye chart. and while I’m asking, I thought of another question
If you wear corrective lenses all the time, do your eyes become dependent on them, meaning that they will never get stronger, almost like building an immunity to antibiotics?
Wow, I think I confused myself on that one, but if you understand what I was trying to ask, answer please. I hate wearing contacts and glasses just the same, considering lacik surgery, but was just curious about all this stuff, and oops sorry, another question, is there any thing different I would need to do besides ask my eye doc about the surgery? meaning is there any waiting period, or anything that he will make me do before he can recommend, or do the surgery. once I decide, I am a very impatiant person, and don’t like to wait, I like instant gratification. I also have an astigmatism will that be a factor in the surgery, meaning that I couldn’t have it done.
sorry so long, I started asking, and a dozen more questions popped into my head =(

What Does The Numbers On My Contact Box Means?

bc-8.5
DIA-14.5
d- -2.50
cyl- -1.75
i have astigmatism, whats my degree for it?

Is My Eye Sight Not That Bad? Wat Does All The Numbers Mean?

im 13 and got an eye exam a little bit ago bc i started not to be able to see things far away (chalk bored etc.) the Doctor said i have slight astigmatism also i have to scrunch my eyes to read or see things far away. every things very blurry far away. um idk what everything means but it says OD -0.50, -0.50, 120 and OS -0.50 what does that all mean? is my eye sight not that bad?

What Do The Numbers And Letters Around A Contact Lens Mean?

I can see numbers “1 2 3″ and a bunch of other letters on my contact lenses and I’m not sure if they’re indicating how I’m supposed to place them on my eyes. I have astigmatism. Help!