XEN Glaucoma Gel Stent Versus Trabeculectomy

Inclusion Criteria: 1. Diagnosis of open angle glaucoma (Primary open angle glaucoma, Pseudoexfoliation glaucoma, Pigmentary dispersion glaucoma) 2. Clinically eligible for both surgeries (Trabeculectomy and XEN) on the discretion of the surgeon (area of healthy, free and mobile conjunctiva in the superior nasal target quadrant) 3. VA logMAR ≤ 1 (VA dec ≥ 0.1) 4. Trabecular meshwork must be visible (with Shaffer angle grade \> 1 in the target quadrant) 5. Age 18 years or older 6. Patient understands the nature of the procedure, is willing to comply with associated follow-up evaluations, and provides written informed consent Exclusion Criteria: 1. Clinical significant cataract 2. Subject has had prior cataract surgery in study eye ≤ 1 months (count to operation) 3. Subject has had prior (incisional) glaucoma surgery (XEN, trabeculectomy, viscocanalostomy, canaloplasty, shunts of any type, collagen implants, etc.). Prior iridotomy is acceptable. 4. Phacic Angle Closure Glaucoma 5. Subject has neovascular, uveitic or angle recession glaucoma or any glaucoma associated with vascular disorders 6. Active inflammation (e.g., blepharitis, conjunctivitis, keratitis, uveitis) 7. Anterior chamber intraocular lens 8. Vitreous present in the anterior chamber 9. Presence of intraocular silicone oil 10. History of corneal surgery, corneal opacities, or corneal disease 11. Impaired episcleral venous drainage (e.g. Sturge-Weber or nanophthalmos) 12. History of dermatologic keloid formation 13. Active diabetic retinopathy, proliferative retinopathy, choroidal neovascularization, branch retinal vein occlusion, central retinal vein occlusion, or other ophthalmic disease or disorder that could confound study results 14. Known or suspected allergy or sensitivity to drugs required for the surgical procedure or any of the device components (e.g., porcine products or glutaraldehyde), 15. Pregnant or nursing women