This is a prospective, observational, non-interventional study of patients scheduled to receive surgical intervention either via XEN or trabeculectomy for open-angle glaucoma. The decision to treat patients with a particular surgical procedure will not be influenced by the study as the treatment decision will continue to be made by the patient and the clinician. There will be no study mandated visits or treatments.

Inclusion Criteria:

• Diagnosed with OAG (Open Angle Glaucoma) and using at least 2 topical IOP-lowering medication classes in the study eye
• Scheduled to receive surgical treatment with either XEN (Xen gel stent) or trabeculectomy in the study eye
• Access to an electronic device with internet capabilities and an email address for completion of PROs (Patient Reported Outcomes)
• Be willing and able to complete PROs (Patient Reported Outcomes) at the specified time points
• Able to provide voluntary, informed consent to participate in this study

Exclusion Criteria:

• Diagnosed with angle closure glaucoma in the study eye
• Presence of a secondary glaucoma, pseudoexfoliation glaucoma, or pigmentary glaucoma
• Presence of neovascular, uveitic, or angle recession glaucoma or any glaucoma associate with vascular disorders
• Prior incisional glaucoma surgery, canal-based surgery, suprachoroidal space-based surgery (trabeculectomy, viscocanalostomy, canaloplasty, shunts of any type, collagen implants, etc.) or a cilio-ablative procedure
• Clinically significant inflammation or infection in the study eye within 30 days prior to the baseline visit (e.g. blepharitis, conjunctivitis, keratitis, uveitis, herpes simplex infection)
• History of corneal surgery, corneal opacities, or corneal disease
• Prior intraocular surgery in either eye ≤ 3 months prior to study enrollment with the exception of uncomplicated cataract surgery in either eye ≥ 1 month prior to study enrollment
• Anticipated ocular surgery in either eye within 6 months of baseline
• Concomitant cataract surgery scheduled at the time of glaucoma procedure

The study eye is defined as the eye receiving surgical intervention with either XEN or trabeculectomy.

Patients who have received prior laser trabeculoplasty will be permitted to participate if all other inclusion/exclusion criteria are met.

For this study, approximately 150 eligible patients (75/group) will be enrolled in Canada, the UK, Germany, and Austria.

Allergan will share de-identified patient-level data and study-level data including protocols and clinical study reports for phase 2 - 4 trials completed after 2008 that are registered to ClinicalTrials.gov or EudraCT, have received regulatory approval in the United States and/or the European Union in a given indication and the primary manuscript from the trial has been published. To request access to the data, the researcher must sign a data use agreement and any shared data is to be used for non-commercial purposes. More information can be found on http://www.allerganclinicaltrials.com/.