Effectiveness And Safety Of Viscoelastic Retention During Preserflo Microshunt Surgery For The Prevention Of Postoperative Hypotony

The aim of this study was to evaluate the safety and clinical effectiveness of intentionally retaining a cohesive viscoelastic substance within the anterior chamber at the conclusion of PreserFlo MicroShunt (PMS) implantation. This technique is proposed as a simple intraoperative modification to help mitigate early postoperative hypotony, a common and potentially vision-threatening complication following glaucoma filtration surgery. By assessing postoperative outcomes, including intraocular pressure control and complication rates, we sought to determine whether this approach can reduce hypotony risk without adversely affecting surgical success.

Division of Ophthalmology, McMaster University, Hamilton, ON, Canada

Retrospective case series of all patients who underwent PMS surgery with retained viscoelastic in the anterior chamber by a single surgeon and had at least 6 months of follow-up. The primary outcome was incidence of hypotony and postoperative interventions. Secondary outcome measures included surgical success defined as an IOP of 18 mmHg or lower and one of the following: IOP reduction >20% from baseline on the same or fewer medications or IOP ≤ baseline on fewer medications. Further surgery for IOP control at any time or loss of light perception were considered failures.

70 eyes of 70 patients were included in the study. Mean IOP decreased from 29.2 ± 5.0 mmHg to 12.9 ± 2.9 mmHg at 12 months (p < 0.001). Medications dropped from 3.7 ± 1.0 to 0.7 ± 1.4 (p < 0.001). Postoperative hypotony occurred in 5 eyes (7%) and resolved within less than one month. Two patients required needling, and two patients (4%) underwent secondary glaucoma surgery. No persistent choroidal effusion or clinical hypotony were observed.

Retaining cohesive viscoelastic in the anterior chamber at the conclusion of PreserFlo MicroShunt surgery appears to be a simple, safe, and effective modification that may reduce the incidence and severity of early postoperative hypotony. In this series, hypotony events were infrequent, transient, and did not result in long-term sequelae such as persistent choroidal effusion or clinically significant hypotony. Importantly, this approach did not compromise intraocular pressure reduction or overall surgical success, supporting its potential utility as an adjunctive intraoperative strategy in glaucoma filtration surgery.