Trabeculectomy Versus Canaloplasty to Treat Glaucoma

Inclusion Criteria: * patients with open angle glaucoma and excavation of 0.4 - 0.8 * 60 eyes of 60 patients (30 patients for trabeculectomy, 30 patients for Canaloplasty) The ratio of female / male is not involved. * Eye pressure under local therapy: 20mmHg and above (corrected with pachymetry table). * Local drug therapy: at least 2 eye pressure lowering ingredients or absolute intolerance to preservatives or eye drops. * general anesthesia possible. * The operation must be signed by the surgeon as a state-of-the-art performed without complication to be evaluated. If the operation does not meet this criterion, the patient is excluded from the study. Exclusion Criteria: * all patients are not included in the group of inclusion criteria, or: * Phenprocoumon therapy. * operation is not done state-of-the-art. * after the surgery: additional eye pressure lowering surgery, cataract surgery, keratoplasty, laser surgery in the anterior eye segment (except suture lysis after trabeculectomy) * Uveitis, or possible inflammation of the eye * Previous eye pressure lowering operations or laser interventions * Corneal Refractive Surgery (pseudophakia allowed)