New XEN63 Gel Stent Implantation in Open-Angle Glaucoma: A Two-Year Follow-Up Pilot Study

Abstract

Purpose: The XEN gel stent was developed to reduce the risks of filtration surgery by standardizing the outflow of aqueous humor into the subconjunctival space. Recently, a modified version of the XEN63 gel stent was introduced. The goal of this study was to assess its efficacy and safety.

Methods: This is a prospective, nonrandomized, observational, consecutive case series study at a single tertiary centre. Patients with open-angle glaucoma with above target intraocular pressure (IOP) despite maximal tolerated medication were included. The primary outcome was a change of median IOP. Secondary outcomes included a change in the number of medications, complete success, needling and complication rates. Success was defined as a lowering of IOP > 20% from baseline and IOP ≤ 14 mmHg. Complete success indicated that the target IOP was reached without medications.

Results: Six patients were included. The median IOP decreased from 35.5 mmHg (25.0-40.0 mmHg) at baseline to 11.5 mmHg (4.0-15.0 mmHg, p = 0.03), and median IOP-lowering medication was reduced from 4.0 (3.0-4.0) at baseline to 0 (0-1.0, p = 0.03) after two years. Five patients (83.0%) had a complete success after two years. Two patients (33.0%) required a needling procedure. Three patients (50.0%) required an intervention due to symptomatic hypotony within the first three weeks postoperatively. Hypotony resolved completely or was asymptomatic after three months.

Conclusion: Our study demonstrated a statistically significant reduction in both IOP and number of IOP-lowering medications. Complications were well manageable and had no long-term sequelae.

Keywords: filtering surgery; glaucoma gel stent; minimally invasive surgery; open-angle glaucoma.

Figure 1

Median intraocular pressure (IOP) at different time points. Whiskers represent range.

Figure 2

Individual intraocular pressure (IOP) of six of seven patients with a follow-up of two years. In case 2, early postoperative hypotony developed during the first postoperative day. The hypotony persisted over the course of the first week resulting in shallow anterior chamber and choroidal detachment. Healon5 ophthalmic viscoelastic device (OVD) was then injected in the anterior chamber. A second OVD injection was required after two days. The anterior chamber was then reformed and the choroidal detachment resolved completely by the end of the first month even though IOP remained lower than 6.0 mmHg. At month three, IOP increased to 20.0 mmHg due to scarring of the filtering bleb. A single needling procedure with mitomycin C was performed to re-establish outflow. This was followed by a remarkable decrease in IOP, which persisted up to the second year after the XEN63^® gel stent implantation. Anterior chamber remained deep; there was no choroidal detachment and the visual acuity recovered fully, so that no further intervention was necessary in this patient. In case 5, a fibrotic bleb developed with an IOP increase to 23.0 mmHg after six months. A single needling procedure was performed which resulted in unmedicated IOP reduction to 13.0 and 11.0 mmHg after one and two years, respectively. In case 7, early postoperative hypotony resulted in shallow anterior chamber and choroidal detachment. Two OVD injections were required during the first two postoperative weeks. Hypotony resolved completely by the end of the second week and no further intervention was necessary up to two years after surgery.

Figure 3

Scatter plot of the baseline and 2-years-postoperative intraocular pressure (IOP).

Figure 4

Median visual acuity at different time points. Whiskers represent range.