The goal of this randomized controlled clinical trial is to learn whether two minimally invasive bleb-forming glaucoma implants can effectively treat adult patients with open-angle glaucoma who require surgical lowering of intraocular pressure (IOP). Specifically, the study evaluates whether the PRESERFLO™ MicroShunt is at least as effective as the XEN®-63 Gel Stent in reducing IOP after surgery. 

The main questions it aims to answer are:

• Does the PRESERFLO™ MicroShunt provide IOP reduction at 12 months that is non-inferior to the XEN®-63 Gel Stent?
• How do the two devices compare over 24 months with respect to medication reduction, need for additional glaucoma procedures, complications, and preservation of visual function and ocular structures?

Participants will:

• Be randomly assigned (1:1) to receive either the XEN®-63 Gel Stent or the PRESERFLO™ MicroShunt during a single glaucoma surgery.
• Attend scheduled follow-up visits over 24 months for eye-pressure measurements, vision testing, visual-field testing, OCT imaging, endothelial-cell counts, and safety assessments.
• Receive standard postoperative care and report any complications or additional treatments during the study period.

Inclusion Criteria:

• >40 years of age
• An established diagnosis of: Primary open angle glaucoma, Normal tension glaucoma, Pigment dispersion glaucoma (PDG) or Pseudoexfoliative glaucoma (PEX)
• Inadequately controlled on maximum tolerated medical therapy.
• Mean Deviation (MD) \