Patients with glaucoma requiring tube shunt surgery, with or without simultaneous cataract surgery, will be enrolled in this prospective randomized controlled study at ten sites across Canada and the United States (to be determined). Patients with highly advanced glaucoma at high risk of fixation loss, neovascular glaucoma, chronic uveitis, marked corneal disease, sulfa allergy, renal disease or any contraindication to diamox use will be excluded.