Aim: To compare outcomes of ab interno XEN gelatin stent (Allergan, Dublin, Ireland) implantation vs trabeculectomy with mitomycin C (MMC).
Materials and methods: A retrospective review was conducted of eyes that underwent standalone XEN implantation or trabeculectomy with MMC at a single institution from 2014 to 2019. Intraocular pressure (IOP), visual acuity, glaucoma medications, complications, and postoperative interventions were evaluated. The primary endpoint was the reduction in IOP at 6 months postoperatively. Secondary endpoints included the incidence of postoperative intervention and complications.
Results: One hundred and seventy-nine eyes were included who underwent XEN (n = 90) or trabeculectomy (n = 89). The mean age was 74.5 ± 7.6 and 68.1 ± 8.2 years old for the XEN and trab groups, respectively (p < 0.001). Baseline IOP for XEN was 17.8 ± 6.0 vs 20.4 ± 9.0 mm Hg for the trab group (p = 0.03). At 6 months, mean IOP for XEN group was 13.5 ± 5.9 mm Hg, representing a 24.1% IOP reduction from baseline (p < 0.001) while mean for trab group was 10.8 ± 4.8 representing a 47% IOP reduction from baseline (p < 0.001). The mean IOP was 2.7 mm Hg lower in trab compared to the XEN group at 6 months (p < 0.003). The number of medications was reduced in both groups from 2.9 ± 1.1 and 3.1 ± 0.9 to 1.1 ± 2.3 and 0.8 ± 1.4 by 6 months postoperatively for XEN and trab groups, respectively (p < 0.001). Complication rates were low for both groups. The needling rate was 30% in XEN vs 7.9% in the trab group (p < 0.001), and 46.1% of eyes in the trab group underwent laser suture lysis. Additionally, IOP reduction and complication rates were similar following XEN in eyes receiving <40 or ≥40 μg of MMC.
Conclusion: XEN implantation produces a substantial reduction in IOP with a favorable safety profile comparable to trabeculectomy. Careful postoperative bleb management is critical to obtain optimum outcomes, and higher MMC doses appear safe and may reduce needling rates.
Clinical significance: This study confirms the safety and efficacy of XEN gelatin stent implantation in comparison to trabeculectomy with MMC.
Tham YC, Li X, Wong TY, et al. Global prevalence of glaucoma and projections of glaucoma burden through 2040: a systematic review and meta-analysis. Ophthalmology 2014;121(11):2081–2090. DOI: 10.1016/j.ophtha.2014.05.013.
Heijl A, Leske MC, Bengtsson B, et al. Reduction of intraocular pressure and glaucoma progression: results from the early manifest glaucoma trial. Arch Ophthalmol 2002;120(10):1268–1279. DOI: 10.1001/archopht.120.10.1268.
Gedde SJ, Feuer WJ, Shi W, et al. Treatment outcomes in the primary tube versus trabeculectomy study after 1 year of follow-up. Ophthalmology 2018;125(5):650–663. DOI: 10.1016/j.ophtha.2018.02.003.
Gedde SJ, Herndon LW, Brandt JD, et al. Postoperative complications in the tube versus trabeculectomy (TVT) study during five years of follow-up. Am J Ophthalmol 2012;153(5):804–814.e1. DOI: 10.1016/j.ajo.2011.10.024.
Lewis RA. Ab interno approach to the subconjunctival space using a collagen glaucoma stent. J Cataract Refract Surg 2014;40(8):1301–1306. DOI: 10.1016/j.jcrs.2014.01.032.
Grover DS, Flynn WJ, Bashford KP, et al. Performance and safety of a new ab interno gelatin stent in refractory glaucoma at 12 months. Am J Ophthalmol 2017;183:25–36. DOI: 10.1016/j.ajo.2017.07.023.
Schlenker MB, Gulamhusein H, Conrad-Hengerer I, et al. Efficacy, safety, and risk factors for failure of standalone ab interno gelatin microstent implantation versus standalone trabeculectomy. Ophthalmology 2017;124(11):1579–1588. DOI: 10.1016/j.ophtha.2017.05.004.
Heidinger A, Schwab C, Lindner E, et al. A retrospective study of 199 Xen45 stent Implantations from 2014 to 2016. J Glaucoma 2019;28(1):75–79. DOI: 10.1097/IJG.0000000000001122.
Karimi A, Lindfield D, Turnbull A, et al. A multi-centre interventional case series of 259 ab-interno XEN gel implants for glaucoma, with and without combined cataract surgery. Eye (Lond) 2019;33(3):469–477. DOI: 10.1038/s41433-018-0243-8.
Marcos Parra MT, Salinas Lopez JA, Lopez Grau NS, et al. XEN implant device versus trabeculectomy, either alone or in combination with phacoemulsification, in open-angle glaucoma patients. Graefes Arch Clin Exp Ophthalmol 2019;257(8):1741–1750. DOI: 10.1007/s00417-019-04341-y.
Lenzhofer M, Kersten-Gomez I, Sheybani A, et al. Four-year results of a minimally invasive transscleral glaucoma gel stent implantation in a prospective multi-centre study. Clin Exp Ophthalmol 2019;47(5):581–587. DOI: 10.1111/ceo.13463.
Reitsamer H, Sng C, Vera V, et al. Two-year results of a multicenter study of the ab interno gelatin implant in medically uncontrolled primary open-angle glaucoma. Graefes Arch Clin Exp Ophthalmol 2019;257(5):983–996. DOI: 10.1007/s00417-019-04251-z.
Smith M, Charles R, Abdel-Hay A, et al. 1-Year outcomes of the Xen45 glaucoma implant. Eye (Lond) 2019;33(5):761–766. DOI: 10.1038/s41433-018-0310-1.
Mietz H, Krieglstein GK. Three-year follow-up of trabeculectomies performed with different concentrations of mitomycin-C. Ophthalmic Surg Lasers 1998;29(8):628–634.
Sanders SP, Cantor LB, Dobler AA, et al. Mitomycin C in higher risk trabeculectomy: a prospective comparison of 0.2- to 0.4-mg/cc doses. J Glaucoma 1999;8(3):193–198. DOI: 10.1097/00061198-199906000-00008.
Kupin TH, Juzych MS, Shin DH, et al. Adjunctive mitomycin C in primary trabeculectomy in phakic eyes. Am J Ophthalmol 1995;119(1):30–39. DOI: 10.1016/S0002-9394(14)73810-3.
Gillmann K, Bravetti GE, Mermoud A, et al. XEN gel stent in pseudoexfoliative glaucoma: two-year results of a prospective evaluation. J Glaucoma 2019;28(8):676–684. DOI: 10.1097/IJG.0000000000001295.
Tan SZ, Walkden A, Au L. One-year result of XEN45 implant for glaucoma: efficacy, safety, and postoperative management. Eye (Lond) 2018;32(2):324–332. DOI: 10.1038/eye.2017.162.
Kitazawa Y, Suemori-Matsushita H, Yamamoto T, et al. Low-dose and high-dose mitomycin trabeculectomy as an initial surgery in primary open-angle glaucoma. Ophthalmology 1993;100(11):1624–1628. DOI: 10.1016/S0161-6420(93)31426-0.
Sheybani A, Dick HB, Ahmed II. Early clinical results of a novel ab interno gel stent for the surgical treatment of open-angle glaucoma. J Glaucoma 2016;25(7):e691–e696. DOI: 10.1097/IJG.0000000000000352.
Galal A, Bilgic A, Eltanamly R, et al. XEN glaucoma implant with mitomycin C 1-year follow-up: result and complications. J Ophthalmol 2017;2017:5457246. DOI: 10.1155/2017/5457246.