Toxic Anterior Segment Syndrome following XEN Gel Stent Implantation: A Rare Complication in Minimally Invasive Glaucoma Surgery - Case Report.

INTRODUCTION: Toxic anterior segment syndrome (TASS) is a rare, sterile, acute inflammatory reaction of the anterior segment following intraocular surgery. Although it is most commonly associated with cataract surgery, it has been reported after a variety of ophthalmic procedures. To our knowledge, no case of TASS following XEN Gel Stent Implantation has been previously described in the literature. CASE PRESENTATION: An 85-year-old pseudophakic woman with primary open-angle glaucoma developed TASS after uneventful XEN63 implantation. Within 24 h postoperatively, the patient presented with diffuse limbus-to-limbus corneal edema, anterior chamber inflammation, and absence of pain or posterior segment involvement. Despite prompt and intensive topical corticosteroid therapy, she developed irreversible corneal decompensation, iris atrophy, and fixed nonreactive mydriasis. No additional cases were identified in the same surgical setting, suggesting a patient- or procedure-specific trigger. Potential causative factors included intracameral agents (lidocaine, acetylcholine, cefuroxime, viscoelastic material), possible migration of mitomycin C through the XEN stent lumen, or an inflammatory response to the gelatin-based device itself. CONCLUSIONS: This case demonstrates that TASS can occur following minimally invasive glaucoma surgery, including XEN Gel Stent implantation, and may result in severe and irreversible ocular sequelae. It underscores the importance of heightened postoperative vigilance and strict preventive protocols even in procedures perceived as low risk.