SB
I had a medical just a couple of weeks ago with the Singapore CAAS Medical Board ( we have to do our medicals with them every two years, in case our friendly neighbourhood doctor is a bit too friendly ) and asked them whether it was permissable here to have the lasik surgery done. They told me that it was OK, and the only requirements were that you could not fly until the second checkup after the surgery ( about two weeks I understand ), and that an eye test would be compulsory every year after that.
Hope this helps, but I suggest you contact them yourself if you are serious about a job here.