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

Abstract

Background: 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. Methods: 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. Results: 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 (p-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 (p = 0.011). Conclusions: 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.

Keywords: XEN® 45 µm; XEN® 63 µm; intraocular surgery; minimally invasive bleb surgery; minimally invasive glaucoma surgery; open-conjunctiva approach; survival analysis.

Figure 1

Surgical technique for the 30G needle-mediated open-conjunctiva ab externo XEN^® 45 and 63 µm implants. (A) Instillation of sub-Tenon’s anesthetic (2% lidocaine with epinephrine) after initial peritomy with Vanna’s scissors. (B) Dissection of conjunctiva and the Tenon’s capsule with Wescott scissors. (C) Application of MMC 0.02% on the scleral bed. (D) Marking at 2 mm from the surgical limbus and creation of the scleral tract with a 30G needle. (E) Manual insertion of the XEN^® implant using non-toothed forceps. (F) Verification of correct tubular filtration at the distal segment of the XEN. (G) Verification of the correct implantation of the device with a gonioscopy lens. (H) Tenon’s capsule closure with interrupted Vicryl 7.0 sutures. (I) Closure of the conjunctiva with interrupted 10.0 Nylon sutures.

Figure 2

Kaplan–Meier analysis for complete (A) and qualified (B) surgical success. Hazard radio (HR) adjusted by baseline IOP and use of bleb space modulators.

Figure 3

Postoperative mean IOP evolution in the XEN^® 45 µm and the XEN^® 63 µm. The error bars indicate standard deviations.

Figure 4

Ab externo open-conjunctiva XEN^®-associated complications. (A) Multifocal serous choroidal detachments after XEN^® 63 µm implantation. (B) Urretz–Zavalia syndrome, toxic anterior segment syndrome, and corneal edema after XEN^® 45 µm implantation. (C) Anterior segment optical coherence tomography (Triton^®, Topcon, Tokyo, Japan) depicting corneal endothelial decompensation with central corneal edema, Descemet’s folds, and epithelial bullae.