A Case of Early PreserFlo MicroShunt Obstruction Following Presumed Inadvertent Ciliary Sulcus Implantation

We report a case of early postoperative PreserFlo MicroShunt (PFM; Santen Pharmaceutical Co., Ltd., Osaka, Japan) obstruction following presumed inadvertent ciliary sulcus implantation. A 67-year-old Japanese man with primary open-angle glaucoma underwent superonasal PFM implantation in the right eye, which had previously undergone cataract surgery, scleral buckling, and microhook ab interno trabeculotomy. The preoperative intraocular pressure (IOP) in the right eye was 26 mmHg on two classes of topical IOP-lowering medications. Although the proximal tip was not visible in the anterior chamber, aqueous humor outflow was confirmed intraoperatively, and the device was left in place. On postoperative day 1, IOP was 24 mmHg, and no filtering bleb was observed. The PFM was removed, and a new device was implanted into the anterior chamber through an adjacent scleral tunnel. The IOP was 6 mmHg on postoperative day 1 after the second PFM implantation. Stereomicroscopic examination of the first explanted PFM device revealed intraluminal pigmented tissue fragments consistent with uveal tissue, although their precise origin could not be established. Bleb needling was performed at five weeks because the IOP had increased to 31 mmHg, presumably due to bleb encapsulation. The IOP was 15 mmHg at three months after reoperation. This instructive case illustrates the importance of confirming the scleral tract trajectory and implant position, as apparently satisfactory intraoperative outflow does not ensure sustained tube patency. These findings should not be generalized to the safety or efficacy of intentional ciliary sulcus implantation.