Exposure of PreserFlo Microshunt: Risk Factors and Surgical Management

Preserflo MicroShunt (PMS) has emerged as a safe and effective subconjunctival implant for lowering intraocular pressure in glaucoma. Although most postoperative complications occur early and are transient, long-term data remain limited—particularly regarding rare but serious events such as device exposure or extrusion, which may threaten ocular integrity. This report presents three clinical cases of PMS exposure with distinct presentations, potential risk factors, and surgical management approaches. In the first case, a pseudophakic patient with primary open-angle glaucoma developed exposure of the device body eight months postoperatively, associated with conjunctival ischemia but without leakage. In the second case, exposure of a non-functioning PMS occurred two years after a second implant was placed in a different quadrant, following early failure of the original device. The exposed implant was removed without compromising IOP control. The third and most severe case involved extensive scleral melting, distal extrusion, and Seidel positivity, requiring device explantation and scleral grafting. Contributing factors included the use of 0.04% mitomycin C, previous surgeries, and intraoperative identification of thin Tenon’s capsule. Based on these cases, PMS exposure may arise through different mechanisms—distal extrusion, body erosion, or conjunctival dehiscence—each necessitating tailored surgical intervention. Awareness of risk factors and prompt management are essential to prevent complications such as infection or hypotony. These findings highlight the importance of careful intraoperative assessment, personalized MMC application, and early detection to ensure long-term safety and device preservation.