What is the limit for contact lenses?

I am currently 18 and have a script of 6.75 (short sighted). I was told that this was really bad for my age which was strange because i dont use the computer very much, although i do study. Anyways, was wondering what was the upper limit for contact lenses because i have another 5 years to graduation and with all the studying, my eyes can only deteriorate more.
Oh, sorry for being ambiguous. I meant how bad can my script get before contact lenses no longer caters for my shortsightedness

Do you mean how old do you have to be to get them? Or how old can you be before you have to stop using them?
Ok, well i don't know about that but wearing glasses or contacts may help improve your eyes a little bit or at least keep your sight at the same level.
Ask your optician next time you go they'll be able to answer any questions and don't worry about sounding daft when you ask questions, if you don't ask you don't learn do you!

You can get Acuvue Oasys up to -12.00. Some contact lens manufacturers will custom-make soft contacts in higher prescriptions, but it will cost more.
And if you're willing to go with RGP lenses, you can pretty much get those in any prescription that you could get glasses in (though I'm told they might not be comfortable past about -20.00)...
Most likely, your eyes will not deteriorate past that point though, especially if you are 18 and only a -6.75 now. A friend of mine was a -6.50 by the third grade and his eyes leveled off around -9.00 (He wears contacts too).
Also, your prescription will be lower with contacts than it will be with glasses. I'm a -6.50 for contacts or a -7.25 for glasses. This is because the distance of the correction from your eye changes the strength you need.
However, if you get past that point, you can always get LASIK...

Do you mean how high can prescriptions go? standard contacts usually go to -12 and then there are some brands that offer extended range(usually special order) that go higher than that. Near sightedness has nothing to do with age or eye strain, but you should consider a pair of glasses to give your eyes a break from your contact lenses.