Ab-interno implantation of XEN 45 microstent in eyes with previous tube shunt surgery for Glaucoma: A retrospective analysis

Authors:

Kai Man Lily Xu¹, Toby Chan².
¹McMaster University, ²McMaster University, Waterloo Regional Campus.

Author Disclosure Block:

K.L. Xu: None. T. Chan: Any direct financial payments including receipt of honoraria; Name of for-profit or not-for-profit organization(s); Alcon, Allergan, Aequus, Bausch & Lomb, Novartis. Any direct financial payments including receipt of honoraria; Description of relationship(s); Speaker honoraria. Membership on advisory boards or speakers’ bureaus; Name of for-profit or not-for-profit organization(s); Aequus, Allergan, Labtician Thea, Bausch & Lomb, Novartis, Johnson&Johnson. Membership on advisory boards or speakers’ bureaus; Description of relationship(s); Advisory board. Funded grants or clinical trials; Name of for-profit or not-for-profit organization(s); Aequus, Alcon. Funded grants or clinical trials; Description of relationship(s); research funding support.

Abstract Body:

Purpose: Tube shunt surgery is often done on glaucomatous eyes deemed to have high risk of surgical failure with trabeculectomy. Over time, however, subconjunctival fibrosis may result in suboptimal filtration. The XEN45 gel stent (Allergan Inc., an Abbvie company) has shown to be a less invasive filter procedure than traditional trabeculectomy or tube shunt, and can be done via ab-interno or ab-externo approach. Ab-externo XEN45 after previous surgery has been reported, but literature on ab-interno XEN45 after tube shunt is scarce. This study aims to investigate the efficacy and safety profile of ab-interno XEN45 implantation as a secondary procedure in patients with suboptimal intraocular pressure (IOP) control after tube shunt surgery.
Study Design: Retrospective case series.
Methods: Medical records of consecutive adult patients who underwent ab-interno XEN45 implantation with subconjunctival mitomycin C by a single surgeon after failed tube shunt surgery were reviewed. Main outcome measures were IOP and number of glaucoma medications pre-operatively, and at post-operative week (POW) 1, post-operative month (POM) 1, 3, 6, and 12. Paired t-test was performed to compare post-operative and pre-operative parameters. Adverse events and further interventions such as bleb needling were noted. Surgery outcomes were categorized as absolute success (IOP < 18mmHg or > 20% IOP reduction without medication), qualified success (IOP < 18mmHg or > 20% IOP reduction with medications), or failure (IOP > 18mmHg and < 20% IOP reduction with maximum tolerated medications).
Results: The study consisted of 7 eyes from 6 patients, with one eye having data only up until POM3. IOP was significantly reduced from 23.9 ± 5.3 mmHg (mean ± standard deviation) pre-operatively to 14.0 ± 5.8 mmHg at POM12 (p < 0.05). Number of glaucoma medications was reduced from 4.3 ± 1.3 pre-operatively to 1.5 ± 1.6 at POM12 (p < 0.05). Hypotony and choroidal effusion was noted in one case which resolved before POM1. Bleb needling was required in 3 eyes (50%). By POM12, 2 eyes (33.3%) were considered as absolute successes, 3 eyes (50%) as qualified successes, and 1 eye (16.7%) as a failure.
Conclusions: Ab-interno XEN45 implantation is a viable secondary procedure if previous tube shunt surgery was insufficient to achieve IOP control. Nonetheless, transient early complications may occur and further interventions such as bleb needling may still be required.