Ab Interno XEN Gel Stent Implantation in Eyes with Previous Tube Shunt Surgery

Purpose: After tube shunt surgery, many factors may contribute to insufficient filtration over time, prompting further intervention to achieve optimal intraocular pressure (IOP) control. This study explores whether ab interno XEN gel stent implantation could be a viable approach in eyes that need further IOP reduction after tube shunt surgery. Methods: This is a retrospective, single-surgeon case series on ab interno XEN45 gel stent implantation in eyes that had previous tube shunt surgery. Main outcome measures were IOP and number of glaucoma medications at the pre-operative visit, post-operative week (POW) 1, and post-operative month (POM) 1, 3, 6, and 12. Adverse events and further interventions were noted. Surgery outcome was qualified as absolute success (IOP ≤ 18mmHg or ≥ 20% IOP reduction without glaucoma medications), qualified success (IOP ≤ 18mmHg or ≥ 20% IOP reduction with glaucoma medications), or failure (IOP > 18mmHg and < 20% IOP reduction with maximum tolerated glaucoma medications). Results: 7 eyes from 6 patients were included in this study. IOP was reduced from 23.9 ± 5.3 mmHg (mean ± standard deviation) pre-operatively to 14.0 ± 5.3 mmHg at POM12 (p < 0.05). Number of glaucoma medications was reduced from 4.3 ± 1.3 pre-operatively to 1.6 ± 1.6 at POM12 (p < 0.05). Hypotony and choroidal effusion were noted in one case which resolved before POM1. Bleb needling was required in 3 of the 7 eyes (43%), with one eye requiring needling twice. By POM12, 2 of 7 eyes (29%) achieved absolute success, 4 eyes (57%) qualified success, and 1 eye (14%) was qualified as failure. Conclusion: Ab interno XEN gel stent can effectively reduce IOP and number of glaucoma medications after failed tube shunt surgery. Nonetheless, further interventions such as bleb needling may still be required to optimize IOP control.