Combined argon laser peripheral iridoplasty and Nd: YAG laser shock wave therapy for recurrent XEN gel stent obstruction due to iris incarceration: A case report

INTRODUCTION: Despite its proven effectiveness and safety profile, the XEN Gel Stent (Allergan Inc., CA, USA) has a small lumen and is therefore likely to become occluded by fibrin, a blood clot, or even the iris. However, few studies have investigated XEN-iris occlusion and how to manage this condition. We describe the first case report of recurrent XEN gel stent obstruction by iris incarceration, which was resolved following a combined treatment with argon laser peripheral iridoplasty (ALPI) and low-energy neodymium-doped yttrium aluminum garnet (Nd: YAG) laser shock wave treatment. PATIENT INFORMATION: A 74-year-old Korean male underwent uncomplicated XEN gel stent implantation and presented with low intraocular pressure (IOP) with a well-functioning filtering bleb during the first postoperative week. On postoperative day 10, the XEN lumen was occluded by the iris and demonstrated an IOP spike of 33 mmHg. Despite the use of pilocarpine, the iris incarceration persisted. Therefore, surgery to reposition the XEN stent was attempted using a gonio-prism and intraocular forceps. After the first revision surgery, the IOP and stent position were stable for 2 weeks. However, recurrent partial obstruction of the stent by the iris, pigment dispersion into the intraluminal space, and an elevated IOP of 24 mmHg were observed later. DIAGNOSIS: Recurrent XEN gel stent occlusion by the iris and intraluminal pigment dispersion. INTERVENTIONS: Combined ALPI and low energy Nd: YAG laser shock wave therapy. OUTCOMES: IOP dropped from 24 mmHg to 10 mmHg immediately and continued to be well-controlled until 3 months later (range: 8–12 mmHg). CONCLUSIONS: To the best of our knowledge, this is the first case report of the efficacy of combined laser treatment for relieving recurrent XEN implant occlusion by the iris. This combination laser treatment might be a relatively safe rescue treatment to restore the patency of a XEN gel stent occluded by the iris, even in cases with recurrent XEN stent obstruction after surgical repositioning.