Use the search feature and archives. There are extended discussions about Ahmed Valve including several patients that went to Canada and Dr. Ahmed did the surgery himself. This type of surgery is only done on the most severe glaucoma cases where medications and lasers are failing to prevent the progression of glaucoma. The surgery is only recommended when the risks of NOT doing the surgery exceed the risks of DOING the surgery. If you are that concerned you can always get a second opinion from another glaucoma specialist.