I had a problem getting my class 1 as my eyes are about -5. I was told, by a CAA doctor, to stop considering laser surgery as this can have complications. Instead I was offered a pre-JAA class 2 (I already had a Class 3 and PPL).
I was told that when I built up my hours to 700 I would be granted a Class 1. Before getting your hopes up, please remember this was pre-JAA and things have changed, but I do now hold a class 1 medical despite being able to see bugger-all without my contacts.
I am now looking for an airline job and do not expect to have my eyes tested before I get offered a job. As for major airlines enforcing the -3 limit, if that was the case they'd have to sack half their senior pilots! We all suffer from deterioration of sight as we get older, but this is compensated for (apparently) by experience.
The moral of this story is; If you really want to fly get whatever medical you can, get some experience and challenge the CAA to find you unfit.
Best of Luck.