My wife has double vision related to rheumatoid arthritis. We had this one optician for something like twenty five years.
As her condition worsened the prism prescription became stronger and harder to make. After three failed attempts with this guy to make the precription the receptionist got really snotty with my wife, as though it was her fault that they could not make the correct glasses.
So we changed opticians, the new guy, (who we picked as he had reattached a detached retina on a friend of ours) spent over an hour with the first examination, explained everything in great detail and made the glasses right the first time.
Good Luck finding someone, shop arround by word of mouth.
Sorry but this guy is in Canada so no good to you.