Anterior Chamber XEN Gel Stent Movements: The Impact on Corneal Endothelial Cell Density

Although there are several examples of glaucoma drainage devices' dislocations in the literature, the movement of XEN gel stents is scarcely documented, and the impact of such displacements on the corneal endothelium remains unknown. In light of the recent global market withdrawal of the CyPass microstent over concerns with regard to endothelial cell loss, we present a case of XEN gel stent dislocation into the anterior chamber, with localized corneal damage.

We describe the case of a 64-year-old female patient who underwent bilateral XEN gel stent implantation for normal-tension glaucoma. While right eye surgery was uneventful, intraocular pressure increased in the left eye, and examination revealed a flat filtration bleb with no microstent visible through the conjunctiva. A 3 mm segment of the XEN stent was visible within the anterior chamber, with corneal contact during eye movement and blinking. Endothelial cell density was measured twice 1 month apart before the XEN gel stent was replaced.

First, our observations confirm that XEN gel stents can dislocate and advance within the anterior chamber. We speculate that this displacement was caused by regular eye rubbing after surgery. Second, this report illustrates that the position of a drainage device within the anterior chamber is dynamic and significantly influenced by eye movements and blinking. Finally, occasional corneal contact of a XEN gel stent can cause a reduction in endothelial cell density of 2.1% in a month, which represents 46.2% of the annual endothelial loss observed by Tan and colleagues in patients with a Baerveldt tube (4.54% annual decrease).