Intraocular Pressure and Medication Changes Associated with Xen Gel Stent: A Systematic Review of the Literature

Abstract

The Xen gel stent (Allergan Inc, an AbbVie company; Dublin, Ireland) was conceived as an option for patients requiring modest IOP reduction but for whom trabeculectomy was not yet indicated. As with any glaucoma surgery, establishing criteria for patient selection and identifying factors that contribute to a high likelihood of success are important. To help guide clinical decision-making, a systematic review of published studies on the gel stent was performed, with the goal of understanding postoperative outcomes based on clinical and patient factors. Results were organized around a series of pertinent clinical questions based on scenarios encountered in clinical practice. Criteria for including studies were intentionally broad, with the objective of simulating the diverse population of glaucoma patients encountered in real-world practice. Outcomes for IOP and medication reduction postoperatively were assessed in various analyses, including in eyes with various glaucoma types and severity; in eyes naïve to surgery as well as those with a history of prior incisional glaucoma surgery; and when surgery was performed as a standalone procedure or at the time of cataract surgery. The results of each of the various analyses were consistent in demonstrating that successful gel stent surgery achieved a postoperative IOP of approximately 14.0 mm Hg and reduction to fewer than 1 glaucoma medication. Additional data are shown on outcomes by method of implant (ab interno vs ab externo); intraoperative use of antifibrotics; and rates of needling in published studies.

Keywords: Xen; bleb; gel stent; glaucoma; glaucoma surgery.

Figure 1

Two graphical depictions of weighted mean IOP over time after gel stent implantation among studies reporting data at baseline and at 12 months, as well as one additional interim time point. A line graph (A) shows the weighted mean IOP among qualifying studies at baseline and at day 1, week 1, and at months 1, 3, 6, 12, 24, and 36 (“n” represents the number of studies reporting data for the given time point and the number at each time points is the weighted mean IOP; additional data is shown in the accompanying table). As shown in a scatter plot (B), IOP outcomes among studies reporting baseline and 12-month data, as well as at least one additional time point, was consistent.

Figure 2

Median difference in IOP from baseline to day 1, to week 1, and to months 1, 3, 6, and 12 among studies reporting data at baseline and at 12 months, as well as one additional interim time point. On the graph, “n” represents the number of studies reporting data for the given time point and the number at each time points is the median difference in IOP from baseline to that time point. Additional data is provided in the accompanying table.