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.