I just want to say that pre-operative limits have been removed. What I mean is that you can still get your first class medical certificate even if anisometropia is over 2 dioptres, provided you meet the requirements with correction.
With new EASA regulations, Europe has gotten a bit closer to FAA standards.
However there might be some airlines with internal and more stringent requirements. One of these is Lufthansa, who won't ever hire a candidate who had a succesful Lasik surgery or myopia is over -3 dioptres, despite meeting the requirements for the safe conduct of a flight.