Had my op. yesterday and am now safely home, and feeling fine.
The anaesthetist knew all about nitrous oxide and B12 - said just as well I had pointed it out as it was just the sort of op. it could have been used at, and wrote himself a reminder not to use it on me.
The surgeon was great too and everything went well, causing no problem with my eyes, her last two patients with this had had big problems. She was delighted as I was.
and don't forget my joke clivealive.