Reproducibility of the water drinking test in treated glaucomatous patients.

BACKGROUND

To evaluate the reproducibility of intraocular pressure peaks and fluctuation elicited during the water drinking test in treated glaucomatous patients with a long follow-up interval.

DESIGN

Retrospective cohort study in a tertiary care practice.

PARTICIPANTS

Thirty-four treated primary open-angle glaucoma patients.

METHODS

All patients underwent the water drinking test performed in two consecutive visits without any change in the therapeutic regimen. The mean interval between tests was 4.85 (range: 3-6) months. Reproducibility of peak and fluctuation during the water drinking test was assessed using intraclass correlation coefficients. Bland-Altman analysis was used to assess the agreement of intraocular pressure peaks and fluctuation measured between two consecutive tests.

MAIN OUTCOME MEASURES: Intraclass correlation and agreement of intraocular pressure peaks and fluctuation between visits.

RESULTS

There were no significant differences in baseline intraocular pressure values (mean ± standard deviation, 11.73 ± 2.36 and 11.61 ± 2.71 mmHg; P = 0.72) and peaks (14.55 ± 3.41 and 15.02 ± 3.66 mmHg, respectively; P = 0.163) detected during the water drinking test between the first and second visits. There was also no significant difference between the average intraocular pressure fluctuation values (2.82 ± 1.99 and 3.41 ± 2.54 mmHg, respectively; P = 0.135). Intraocular pressure peaks and fluctuation presented intraclass correlation coefficients of 0.85 (P < 0.001) and 0.50 (P < 0.001), respectively.

CONCLUSIONS

Our results demonstrate excellent reproducibility of intraocular pressure peaks during the water drinking test. Intraocular pressure fluctuation did not reveal good reproducibility, though. These results emphasize the applicability of this test to assess treatment efficacy in daily practice and interventional studies.