How long do contacts last when they're unopened in there cases?

I have horrible eye vision and been wearing glasses since I was little, I got contacts around September 07.





I looked on the boxes of them and it looks like the year, but Im not sure. It says something like 2010/03 and some others say 2012/08.





I was wondering how long they last?How long do contacts last when they're unopened in there cases?
The numbers you refer to are expiration dates. Contacts are packed in sterile saline solution and auto-claved to sterilze them.





2010/03 indicates that lens is safe to use until the end of March 2010.





2012/08 indicates that lens is safe to use until the end of August 2012.





Once you open the package and wear the lens, then the usage expires in one day, two weeks, 4 weeks whatever the safety rating is for that brand of lens.