Objective: To evaluate the clinical outcomes of Preserflo MicroShunt (PMS) implantation with mitomycin C (MMC) in managing refractory childhood glaucoma previously treated with Ahmed Glaucoma Valve (AGV).

Methods: Single-arm retrospective cohort study. Methods: 23 eyes of 22 patients with refractory childhood glaucoma and a history of AGV implantation. Methods: All patients underwent PMS implantation with intraoperative MMC (0.04% for 2.5 minutes). Primary endpoints included intraocular pressure (IOP) reduction, reduction in antiglaucomatous medications, and surgical success. 'Complete success' was defined as achieving target IOP without medications; 'qualified success' allowed for medications. Safety parameters included intra- and postoperative complications and the need for further interventions. Methods: IOP reduction, antiglaucomatous medications reduction, and surgical success rates.

Results: Median follow-up was 23 months (IQR: 18-41). Mean baseline IOP was 27.0 ± 4.3 mmHg with 3.2 ± 0.5 medications. At one year, IOP decreased to 14.1 ± 4.4 mmHg (-47.0%) with 0.4 ± 1.0 medications, and to 16.9 ± 3.6 mmHg (-40.2%) with 1.2 ± 1.5 medications at two years. Overall success rates for ≥20% IOP reduction were 91.3% at one year (69.9% complete success) and 72.7% at two years (45.5% complete success); for ≥30% reduction, they were 82.6% and 63.6%, respectively. During follow-up, one case of device extrusion was observed at 3 months, and another required surgical revision at 5 months.

Conclusions: PMS implantation with MMC offer a valuable surgical option for managing refractory childhood glaucoma following AGV. The procedure achieved substantial reductions in both IOP and medication burden. Larger studies with extended follow-up are recommended to confirm its long-term efficacy.