Xen implant fracture during needling procedure

PURPOSE: The XEN implant is a small hydrophilic stent designed to be implanted permanently for the treatment of glaucoma. As with other bleb-forming surgical procedures, needling is part of postoperative care. We describe 3 cases of XEN fracture of the subconjunctival portion that occurred during the needling procedure. METHODS:The purpose of this study was to describe the clinical and anatomic outcomes in 3 cases of XEN fracture caused by the needling procedure. RESULTS:In our case series of XEN procedures (n=170), bleb needling has been performed in 98 cases (57.6%). In 3 cases (3.1%), we observed unintentional damage to the implant after the procedure.The mean distal segment length of the fractured XEN measured 0.83 (range: 0.7 to 1) mm. Despite the adverse event, the mean IOP changed from 25.0 (range: 21 to 30) mm Hg before needling to 12.0 (range: 10 to 14) after needling, with a mean follow-up of 15.3 (range: 11 to 18) months. No vision-threatening complications were recorded during the entire follow-up. CONCLUSIONS: XEN fracture related to the needling procedure should be considered as a possible adverse event of bleb management. Because XEN is composed of a soft and flexible gelatin material, it could be easily damaged by the needle. The fracture does not seem to impair the efficacy of the draining device. As a matter of fact, according to Poiseuille's laws, shortening of the implant's length decreases the resistance while increasing the flow rate. Despite our positive results, it is recommended to preserve the integrity of the implant.