Hi. I'm online and happy to answer your question today.
That should have no effect what so ever on your glaucoma surgery, healing or final eye pressure.
Smoking marijuana three weeks prior to surgery should also not have any different effects on your anesthesia then smoking a tobacco cigarette would.
Also, in the majority of cases trabeculectomy surgery for glaucoma is done under local anesthesia with a anesthesiologist or CRNA standing by to make sure you are comfortable. This is called MAC. During this surgery you are awake and breathing on your own.
Also, just as an aside marijuana, contrary to popular belief, does not do much to lower the eye pressure in people who suffer from glaucoma.
Thanks for your feed-back. I am pleased with your prompt reply.