Reproducibility of the Time of Intraocular Pressure Peaks During Water-drinking Test in Patients Treated for Open-angle Glaucoma

Purpose: To evaluate the reproducibility and intra-eye similarity of the intraocular pressure (IOP) peaks induced by the water drinking test (WDT) in treated glaucoma patients. Methods: This prospective cohort study evaluated 99 patients (198 eyes) who were treated for primary open-angle glaucoma. All patients underwent WDT in two consecutive visits with no change in their current therapy. The interval between the tests was 4 four to six months. The tests were administered at a similar time (4:00 PM ± 1 hour). The reproducibility of the time of the IOP peaks and the correlation between the peak time of both eyes during the two consecutive WDT sessions were assessed. Results: Of all IOP peaks, 59.6% and 71.7% occurred at the same time during the two WDT sessions in the right and left eyes, respectively. In the first and second WDT sessions, the agreements in IOP peak time between the right and left eyes were 60% and 63%, respectively. Conclusion: The IOP peak time between the two consecutive WDT sessions was moderately reproducible, and there was a moderate agreement in the peak time between the two eyes. In light of these findings, clinicians should avoid performing simplified versions of WDT to evaluate IOP peaks.