Reproducibility of the water-drinking test in patients with exfoliation syndrome and exfoliative glaucoma.

PURPOSE To evaluate the reproducibility of intraocular pressure (IOP) peaks and fluctuations detected during the water-drinking test (WDT) in patients with exfoliation syndrome (XFS) and exfoliative glaucoma (XFG). METHODS This prospective study included 34 XFS and 30 XFG patients. Each patient was evaluated twice, with the two WDTs performed on a 30-day interval. We recorded IOP peak (highest IOP during the WDT) and IOP fluctuation (IOP peak minus IOP before the test). Bland-Altman analysis was applied to assess the agreement of IOP peaks and fluctuations between the two consecutive visits. We defined reproducible as within 4 mmHg for IOP peak and within 2 mmHg for IOP fluctuation. RESULTS There were no significant differences in IOP values, IOP peaks and IOP fluctuations between the two visits for both XFS and XFG patients (p > 0.05, for all). The coefficient of repeatability for IOP peak was 2.5 mmHg and 3.5 mmHg in XFS and XFG patients respectively and for IOP fluctuation, it was 2.1 mmHg and 2.2 mmHg. None of the XFS or XFG patients had an IOP peak difference higher than 4 mmHg. Intraocular pressure (IOP) fluctuation differences above 2.0 mmHg were found in 8.8% of XFS patients and 16.6% of XFG patients. CONCLUSIONS Intraocular pressure (IOP) peak and IOP fluctuation have a reproducibility, both in XFS and in XFG.