Glaucoma is a neurodegenerative disease with an accelerated and progressiv retinal ganglion cell loss and concomitant visual field defects. Glaucoma can be treated with eye drops, laser therapy or surgery. Various surgical approaches to lower intraocular pressure are available, amongst which trabeculectomy is the gold standard. Recently minimal invasive glaucoma surgery has been introduced and has become a good alternative to trabeculectomy. Randomized clinical trials investigating the postoperative outcomes of various types of glaucoma surgery are limited.

150 Patients will be randomized to one of the 3 surgeries. Trabeculectomy Preserflo® or Xen® will be done according to a standard protocol Data will be collected for 5 years after surgery, Visual Acuity, Applanation Tonometry, Slit lamp Biomicroscopy, Endothelial cell cound, visual fields, optical coherence tomography of the optic disc, retina and anterior segment, impression cytology and life quality will be done on day of enrollment and during followup. Mean Intraocular pressure and number of glaucoma medications, Endothelial cell loss, visual acuity, visual fields and assessment of life quality will be assessed during the post-operative follow-ups at one week, one month, 3 months, 6 months, 9 months, 1 year, 2 years, 3 years, 4 years and 5 years after surgery.

Inclusion Criteria:

• Patiens with glaucoma in which surgery is indicated to reach target intraocular pressure
• Subjects not anticipated to require any further surgery in the next 12 months

Exclusion Criteria:

• Patients who do not want to make follow-ups at the department
• angle closure, uveitic, neovascular, congenital glaucoma, iridocorneal endothelial syndrom, Axenfeld-Rieger syndrom.
• Prior filtering glaucoma surgery, suprachoroidal stent, retinal surgery, corneal graft surgery or cyclophotocoagulation
• Any major ocular inflammation up to 30 days prior to surgery
• Conjunctival scarring
• Allergy to any drugs required for the protocol