Recanalization of the PRESERFLO MicroShunt With a 9-0 Nylon Suture: A Case Report

Clinical studies have evaluated the safety and efficacy of PRESERFLO MicroShunt (PMS) (Santen Pharmaceutical, Osaka, Japan) implantation, suggesting that this surgery is associated with fewer serious complications and significant intraocular pressure (IOP) reduction. Although there have been reports of iris obstruction at the tip of the tube, no cases of luminal occlusion at the mid-portion of the tube or its management have been reported. This case report describes a 57-year-old man who underwent PMS for primary open-angle glaucoma (POAG) in the right eye. One month after surgery, the IOP in the right eye had increased to nearly 40 mmHg. Initial needling around the distal end of the tube was attempted but proved ineffective. We then examined the tube lumen using anterior segment optical coherence tomography (AS-OCT), which revealed a suspected luminal obstruction at the center of the tube. Upon removal of the tube, intraluminal tissue debris was found at the center of the lumen. A 9-0 nylon suture was inserted into the lumen to dislodge and remove the debris, after which the tube was reinserted. Postoperatively, a well-formed filtration bleb was observed, and the IOP decreased to 8 mmHg. One year after surgery, the IOP in the right eye remained stable at 12 mmHg, with no evidence of re-occlusion of the tube. The insertion of a 9-0 nylon suture may be an effective method for clearing luminal debris in PMS tubes. In addition, AS-OCT is a useful tool for detecting tube lumen obstructions.