Sorry to hear of his troubles, that's no fun anyway and even less so on vacation.
First, I'd ask his own ophthalmologist for a recommendation. Most specialists know others in their field, either from school or conferences or such. Or he/she likely has contacts through a professional organization. Then take that short-list and see if any participate with your insurance. I know around here it can be hard to get a specialist's appointment (even ophthalmologists) on short notice, so it could help immensely to have some form of "referral" from the current treating physician.
Alternatively, try checking your insurance website to search for a specialist in the area. Usually you can put in an address and search for who is closest.
Good luck and enjoy your vacation!