Chronic Intraocular Inflammation as a Risk Factor for XEN Gel Stent Occlusion: A Case of Microscopic Examination of a Fibrin-obstructed XEN Stent

Introduction: In recent years microinvasive glaucoma surgery has risen in popularity. Among microinvasive glaucoma surgery options is the XEN gel stent (Allergan Plc, Dublin, Ireland), a 45 mu m wide ab-interno microstent. It has proven effective in lowering intraocular pressure (IOP) with low complication rates. However, XEN gel stents can become obstructed and cause postoperative rise in IOP. The causes and predicting factors for such obstructions still requires further research. Case Report: We describe the case of a 69-year-old male patient, with traumatic glaucoma and chronic intraocular inflammation showed by laser flare photometry, following childhood trauma and anterior segment surgery. Uncontrollable IOP despite maximal anti-glaucomatous therapy was managed with XEN-augmented Baerveldt surgery. Despite good initial filtration and IOP control, the XEN stent became obstructed and was surgically replaced. After a month, the new stent became obstructed and was replaced by a thicker-lumened Baerveldt tube. This restored good filtration, and adequate IOP was maintained postoperatively. Microscopic examination of the obstructed XEN stent showed a dense fibrin plug. Discussion and Conclusions: This case report shows that fibrin formation could be an important factor in XEN gel stent obstruction, even in initially successfully filtering stents. The association of fibrinogenesis and intraocular inflammation could add a note of caution to the use of XEN gel stents in complicated cataract surgery, or advocate for aggressive anti-inflammatory treatments postoperatively. This could lead to a refinement in success predictors and better patient selection for XEN surgery. Finally, this could open the way to new management options for persistent obstructions, including pharmaceutical fibrinolysis.