Long-term efficacy and safety of XEN-45 gel stent implantation in patients with normal-tension glaucoma

Abstract

Background: Minimally invasive bleb surgery using the XEN-45 gel stent has not been established for the treatment of normal-tension glaucoma (NTG). The main objective of this study was to evaluate the long-term treatment efficacy and safety of XEN-45 in eyes with uncontrolled NTG.

Methods: A retrospective analysis of patients with NTG who underwent XEN-45 gel stent implantation at university hospital Tuebingen between 2016 and 2021. The primary outcome measure was surgical success after three years defined as lowering of intraocular pressure (IOP) of ≥ 20%, with target IOP between 6 and 15 mmHg. Success was complete without and qualified irrespective of topical antiglaucoma medication use. The need for further glaucoma surgery, except for needling, was regarded as a failure. The secondary outcome measures included changes in mean IOP, number of antiglaucoma medications, and needling and complication rates.

Results: Twenty-eight eyes from 23 patients were included in the final analysis. Complete and qualified success rates were 56.5% and 75% after three years, respectively. Mean postoperative IOP ± standard deviation decreased significantly after three years from 19.3 ± 2.0 mmHg at baseline to 13.7 ± 4.2 mmHg (n = 22; p < 0.0001). The median number of antiglaucoma medications decreased from 2 (range 0-4) to 0 after three years (range 0-3; p < 0.0001). Sixteen eyes (57%) required a median of 1 (range 1-3) needling procedures. One eye required further glaucoma surgery. No sight-threatening complications were observed.

Conclusion: The XEN-45 stent is effective and safe for the long-term treatment of NTG. However, needling was frequently required to improve outcomes.

Keywords: Filtering surgery; Gel stent; MIBS; MIGS; Minimally invasive glaucoma surgery; Needling; Normal-tension glaucoma.

Fig. 1

Evolution of postoperative mean intraocular pressure. Individual intraocular pressure (IOP) readings (a) are plotted across post-surgery visits. The graph delineates postoperative mean IOP development. Dotted horizontal lines demarcate the three IOP target zones (grey = primary outcome at 6 ≤ IOP ≤ 15 mmHg). IOP readings at one and three years (b) are compared to medicated baseline values. The diagonal line implies no change, the dotted diagonal line demarcates a 20% IOP reduction, and horizontals lines indicate post-surgery IOP targets

Fig. 2

The number of patients using individual topical antiglaucoma medication. The legend indicates the number (0–4) of individual active antiglaucoma agents being used at post-surgery visits. No systemic intraocular pressure lowering medication was indicated throughout the post-surgery observation

Fig. 3

Kaplan-Meier survival probabilities for surgical success. Surgical success was defined as less than two consecutive intraocular pressure readings without a ≥ 20% reduction from baseline and target values within (A) ≥ 6 mmHg and ≤ 18 mmHg, (B) ≥ 6 mmHg and ≤ 15 mmHg and (C) ≥ 6 mmHg and ≤ 12 mmHg. Success was considered complete without and qualified irrespective of the use of additional antiglaucoma medication