Incidence, risk factors, and outcomes of numerical hypotony and choroidal effusion following PRESERFLO MicroShunt implantation

Purpose To evaluate the incidence, outcomes, and risk factors of numerical hypotony (NH) and choroidal effusion (CE) following standalone PRESERFLO MicroShunt (PMS) implantation. Methods Primary open‐angle glaucoma (POAG) and pseudoexfoliative glaucoma (PXG) patients with uni‐ or bilateral surgery at a tertiary university hospital were retrospectively evaluated. Kaplan–Meier estimates of first‐operated eyes were used to analyse the cumulative incidence of NH (intraocular pressure [IOP] of <6 mmHg), CE, and CE requiring intervention. Risk factor analyses were performed using generalised linear mixed models on the patient level, including bilateral cases. Results In total, 370 patients (235 POAG and 135 PXG) and 435 eyes (288 and 147) were included. The PXG group had a significantly higher incidence of NH (83.7% vs. 69.4%) and CE (34.6% vs. 20.6%). Interventions for CE were required significantly more in PXG patients (20.7% vs. 7.4%). The median CE duration was significantly longer in the PXG group (14 days vs. 7 days). The following risk factors were identified: PXG (development of NH, CE, and CE requiring intervention); spherical hyperopic refractive error (CE and CE requiring intervention); male sex and higher age (CE); number of preoperative medications (CE requiring intervention), lower preoperative IOP (NH), and higher postoperative IOP drop (CE). The 6‐month visual outcomes were not influenced by the hypotony criteria, but significantly more eyes treated for CE required subsequent bleb revisions. Conclusion PXG and hyperopic eyes were at risk for developing postoperative CE requiring intervention. They should be monitored more closely and would benefit from primary intraluminal stenting.