The Xen gelatin microstent (Allergan, CA, USA) is a 6mm hydrophobic, bleb-forming microinvasive glaucoma surgery (MIGS).1 Creation of a filtering bleb through the gel stent and under the conjunctiva lowers intraocular pressure (IOP) by bypassing the natural outflow pathway of aqueous. Currently three Xen models have been developed: 45, 63, and 140 um internal lumen diameters.2 XEN45 ab interno gelatin stent was the first to be approved for clinical use in Canada.3 A recent retrospective cohort study showed comparable safety and risk of failure to trabeculectomy.4 Amongst the main advantages of this device is the ability to create a bleb without dissecting and disrupting tissue, thus decreasing the amount of wound healing and potentially limiting bleb failure. Recently, the XEN63 ab interno gelatin stent was approved by Health Canada for clinical use in Canada. Being a new device, to date, no study has examined the effect of XEN63 ab interno gelatin stent on anti-glaucoma drops burden and IOP. The aim of this study is to investigate the safety and efficacy of the XEN63 ab interno gelatin stent to provide insights for ophthalmologists who will want to add this technique to their practice.

• This is a prospective, single-arm, open-label clinical trial designed to demonstrate the safety and IOP-lowering effectiveness of XEN 63. Approximately 29 patients who are scheduled to undergo glaucoma surgery with XEN63 implantation will be enrolled and followed for up to 12 months postoperatively. Enrollees will follow the standard of care visits (pre-op, post-op day 1, post-op week 1 and post op month 1) where they will undergo a full eye exam (visual acuity, refraction, slit lamp exam and intraocular pressure measurement). In addition to the standard of care visit, enrollees will have 2 additional visits (post-op month 6 and post-op month 12) where they will undergo a full eye exam. Additional tests include a Visual Field assessment and Endothelial cell count on their pre-op visit, post-operative month visit 6 and post-op month 12 visit.

Inclusion Criteria:

• Patients aged 30-90 Primary open angle glaucoma on maximum tolerated medical therapy Going to receive XEN63 ab interno gelatin stent with or without MMC in study eye ± cataract surgery

Exclusion Criteria:

• Other forms of glaucoma
• Previous glaucoma shunt/valve in the target quadrant of study eye
• Presence of conjunctival scarring, prior conjunctival surgery or other conjunctival pathologies (e.g., pterygium) in the target quadrant of study eye
• Active inflammation (e.g., blepharitis, conjunctivitis, keratitis, uveitis), active iris neovascularization or neovascularization of the iris within six months of the surgical date
• Presence of anterior chamber intraocular lens, intraocular silicone oil, vitreous present in the anterior chamber, impaired episcleral venous drainage (e.g., Sturge-Weber or nanophthalmos or other evidence of elevated venous pressure)
• 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), history of dermatologic keloid formation.
• Prior CPC, corneal graft (PKP, DALK, DSAEK, DMEK)
• Other forms of combined surgery (cornea, retina) besides cataract surgery

Patients scheduled to undergo Xen 63 implantation for open angle glaucoma with or without cataract surgery