Delayed Obstruction of XEN Gel Stent by Cell Debris in Primary Open-angle Glaucoma: A New Insight into the Pathophysiology of Filtration Device Failure

Abstract

Aim: The aim of this report is to explore the risk factors of XEN stent obstruction, suggesting the need for a stricter control of these factors and highlighting areas for further research.

Background: Despite its proven effectiveness and safety profile, XEN gel stents (Allergan Plc, Dublin, Ireland) can become obstructed. The causes and predicting factors for such obstructions still require further research. While hyphema has long been known to be responsible for secondary glaucoma through trabecular obstruction, it has not been associated, to date, with XEN gel stent obstruction.

Case description: We describe the case of a 55-year-old female patient with primary open-angle glaucoma (POAG) who underwent bilateral XEN gel surgery. Her left eye developed a 2 mm postoperative hyphema, which resolved spontaneously within 8 days. Intraocular pressure (IOP) normalized at 12 mm Hg and increased to 50 mm Hg after 1 month in an otherwise normal-looking eye. Intraoperative examination revealed a nonfunctioning XEN gel stent, which was replaced and sent for laboratory analysis. Macroscopic examination of the tube confirmed obstruction with cellular debris. Tube replacement restored good filtration.

Conclusion: This case report confirms cellular debris as a potential cause of XEN gel stent occlusion, suggesting that aqueous red blood cells (RBCs) could potentially pose a threat to the microstents' patency even in cases when the bleeding was minimal and self-limited and where the IOP was still controlled at the time of full hyphema resolution. This observation could lead to recommendations for a stricter control of bleeding risk factors prior to microinvasive glaucoma surgery (MIGS), and it raises the question of whether anterior chamber (AC) washout should be advised in postoperative hyphema.

Clinical significance: This case highlights some previously unreported risk factors for XEN stent obstruction and suggests that stricter control of bleeding and monitoring of patients following hyphema could improve surgical outcome.

How to cite this article: Gillmann K, Bravetti GE, Mansouri K. Delayed Obstruction of XEN Gel Stent by Cell Debris in Primary Open-angle Glaucoma: A New Insight into the Pathophysiology of Filtration Device Failure. J Curr Glaucoma Pract 2019;13(3):113-115.

Keywords: Blockage; Glaucoma; Glaucoma surgery; Hyphema; Microinvasive glaucoma surgery; Obstruction; Red blood cells; XEN.