Defining the role of ab externo Xen gel stent in glaucomatous eyes with prior failed surgical intervention

PURPOSE: To evaluate the safety and efficacy of Xen45 Gel stent (Xen; Allergan) in eyes that have failed prior surgical intervention, compared to traditional glaucoma drainage device (GDD) or continuous-wave cyclophotocoagulation (CPC). Since this population has low expected success rates with additional surgery, it is vital to compare to standard-of-care surgical options. METHODS: Retrospective, single-center, case–control study of ab externo transconjunctival Xen shunt in eyes that have previously undergone trabeculectomy and/or GDD surgery. Postoperative data were collected for 18 months. Failure was defined as no light perception, additional glaucoma surgery required, or intraocular pressure (IOP) of < 6 mmHg after 6 weeks postoperatively. RESULTS: Eighteen Xen eyes and 36 control eyes matched on both glaucoma type and previous glaucoma surgeries were included. Seventy-two percent had primary open angle glaucoma, 11% uveitic, 6% primary angle closure, 6% pseudoexfoliation, and 6% pigmentary glaucoma. Fifty-six percent of eyes in each group had prior trabeculectomy, 28% of Xen and 31% of control eyes had prior GDD, and 17% of Xen and 14% of control eyes had both. Baseline medicated IOP was lower in the Xen group (21.8 ± 7.2) compared to controls (27.5 ± 9.4, P = 0.043). The cumulative failure rate at year 1 was 17% for Xen and 20% for controls (P = 0.57). Mean survival time was 14.1 (± 1.5) months and 11.4 (± 0.6) months for controls. There was no difference in minor complication rates between groups (P = 0.65), but the Xen group had a significantly lower rate of serious complications (P = 0.043) defined as vision threatening or requiring surgical intervention in the operating room. When censored for additional glaucoma procedures, there were no differences at year 1 in IOP, change in IOP, number of IOP-lowering medications, or number of medications reduced from baseline. CONCLUSIONS: The Xen shunt provides a reasonable alternative to current standard of care, with a similar failure rate at year 1, with a noninferior IOP reduction compared to GDD and CPC, and a preferred safety profile.