Efficacy and Safety of Open-Conjunctiva Ab Externo 63 µm vs. 45 µm XEN® Gel Stent in Glaucoma Surgery: One-Year Follow-Up

<b>Background</b>: To compare the efficacy and safety of the XEN^® 63 µm and 45 µm devices with the ab externo open conjunctiva with a 30G needle approach. <b>Methods</b>: A retrospective, non-randomized and single-center study was conducted. Consecutive eyes undergoing a XEN^® 63 µm implant were compared with a matched cohort of cases with a XEN^® 45 µm implant. Standalone and combined procedures with phacoemulsification were included. <b>Results</b>: A total of 28 XEN^® 45 µm and 28 XEN^® 63 µm were included. Complete surgical success was achieved in 17 cases (60.7%) in the 45 µm group and in 20 cases (71.4%) in the 63 µm group, with no statistical differences. One year after the surgery, the mean IOP was 13.8 ± 3.3 mmHg for the 45 µm group and 12.4 ± 4.2 mmHg for the 63 µm group (<i>p</i>-value > 0.05). Likewise, the use of glaucoma medication was lowered in the 63 µm device (0.32 ± 0.87) compared to the 45 µm device (0.39 ± 0.86), with no statistical significance. Postoperative hypotony was more frequent in the 63 µm device (39.3%) than in the 45 µm group (28.6%), with no statistical differences. However, hypotony-associated complications (including choroidal detachment, hypotony keratopathy, and hypotony maculopathy) were significantly higher in the 63 µm group (<i>p</i> = 0.011). <b>Conclusions:</b> Although the XEN^® 63 µm may offer a greater IOP-lowering effect with better complete surgical success, no significant differences were detected compared to the 45 µm device. Hypotony-related complications were higher in the XEN 63 µm, although most of them resolved with conservative management.