Comparative Evaluation of Water Drinking Test Response in Advanced Glaucoma Patients with Prior Preserflo MicroShunt and Trabeculectomy Surgery.

PURPOSE: To evaluate the differences in intraocular pressure (IOP) response to the water drinking test (WDT) in advanced glaucoma patients following trabeculectomy or Preserflo MicroShunt implantation. METHODS: This prospective study included 30 eyes from 29 advanced glaucoma patients: 15 underwent trabeculectomy, and 15 received the Preserflo MicroShunt. Baseline IOP was measured using Goldmann applanation tonometry, followed by WDT involving the consumption of 10 mL of water per kilogram of body weight over 5 min. IOP was measured at 15-min intervals until it returned to baseline. Outcomes included peak IOP, time to peak IOP, IOP fluctuation, and time to return to baseline. RESULTS: Baseline IOP was comparable between groups (trabeculectomy: 14.83 ± 2.28 mmHg; Preserflo: 15 ± 1.23 mmHg, P = 0.515). The peak IOP and IOP fluctuation were also similar (P = 0.978 and P = 0.614, respectively). However, trabeculectomy patients exhibited a shorter time to peak IOP (27 ± 5.6 min vs. 36.25 ± 9.8 min, P = 0.017) and faster return to baseline (55 ± 4.8 min vs. 57.25 ± 9.8 min, P = 0.03). CONCLUSIONS: Both trabeculectomy and the Preserflo MicroShunt effectively controlled IOP during WDT, with the Preserflo MicroShunt demonstrating noninferiority in overall IOP control. Trabeculectomy exhibited superior dynamic outflow capacity, making it suitable for patients requiring aggressive IOP reduction.