My experience is that the CASA Medical Section don't have a lot of experience with LASIK and it throws them a bit.
Rather than just getting the surgery done and waiting a month, I'd get straight on to them. With a bit of luck you might be without a medical for one month instead of two.
With me the first person didn't know what to do and stuffed me around for weeks. Eventually I spoke with a supervisor who fixed and updated my medical on the spot.