We examined the safety and efficacy of the open conjunctiva ab externo approach for XEN45 gel stent implantation. There was a significant reduction in intraocular pressure (IOP) and number of glaucoma medications at 12 months follow-up. This study aims to determine the safety and efficacy of the open conjunctiva ab externo approach to XEN45 stent implantation. Retrospective chart review of all patients between July 2018 and March 2020 who underwent XEN45 implantation. IOP and the number of glaucoma medications were measured at the preoperative, 1 day, 1 week, 1 month, 3 months, 6 months, and 12 months postoperative appointments. The primary outcome of this study is the number of cases achieving complete success at 12 months postoperatively. Forty-four eyes of 44 patients were included. Mean preoperative IOP was 26.2±8.7mmHg on 3.2±0.7 IOP-lowering medications. At 12 months postoperative, mean IOP was 18.9±9.1mmHg (n=35, P <0.0001; mean reduction of 27.9%) on 0.9±1.4 (n=35, P <0.0001) IOP-lowering medications. Postoperative needling was performed in 5 cases (11.4%). Of the 35 cases with a postoperative visit at 12 months, complete success was achieved in 14 cases (40.0%) and qualified success in 3 cases (8.6%). Eighteen cases (51.4%) were recorded as failures at 12 months, comprised of 4 cases requiring reoperation for glaucoma (2 XEN45 implants, 1 trabeculectomy, and 1 Baerveldt implant), and 14 cases that did not meet the IOP-lowering criteria for success. During the postoperative course, there was 1 case of self-limited hypotony, 2 self-resolving choroidal effusions, and 3 cases of bleb leakage. The open conjunctiva ab externo approach to XEN45 implantation achieved successful levels of IOP reduction in 48.6% of glaucoma cases within the first year. The most common adverse events included the need for additional glaucoma surgery (excluding needling procedures), transient hypotony, and bleb leak.