Glaucoma is the second most common cause of blindness in the world, second only to cataracts. This study will assess how safe and effective a glaucoma gel stent is when implanted using the ab interno (inside the eye) and ab externo (outside the eye) approach. Adverse events and intraocular pressure will be assessed. XEN63 is an investigational device for the treatment of intraocular pressure (IOP) in patients with glaucoma when both medical and conventional surgical treatments have failed (for US approval) and when medical treatments have failed (for outside US \[OUS\] approval). Participants will be placed in one of two groups called study arms. One group will receive the XEN63 gel stent ab interno (inside the eye) and the other group will receive the XEN63 gel stent ab externo (outside the eye). Approximately 130 participants aged 45 years or older with glaucoma will be enrolled in this study at approximately 32 sites in the United States. Participants will receive XEN63 implanted using either the ab interno approach or the ab externo approach on Day 1 and will be followed for 12 months. Participants will attend regular visits during the study at a hospital or clinic. The safety and effect of the gel stent on your glaucoma will be checked by medical assessments and eye examinations.