Reproducibility of the water drinking test.

OBJECTIVES: To investigate the reproducibility of the water drinking test in determining intraocular pressure peaks and fluctuation. It has been suggested that there is limited agreement between the water drinking test and diurnal tension curve. This may be because it has only been compared with a 10-hour modified diurnal tension curve, missing 70% of IOP peaks that occurred during night. METHODS: This was a prospective, analytical and comparative study that assesses the correlation, agreement, sensitivity and specificity of the water drinking test. RESULTS: The correlation between the water drinking test and diurnal tension curve was significant and strong (r=0.93, Confidence interval 95% between 0.79 and 0.96, p<01). A moderate agreement was observed between these measurements (pc=0.93, Confidence interval 95% between 0.87 and 0.95, p<.01). The agreement was within±2mmHg in 89% of the tests. DISCUSSION: Our study found a moderate agreement between the water drinking test and diurnal tension curve, in contrast with the poor agreement found in other studies, possibly due to the absence of nocturnal IOP peaks. CONCLUSIONS: These findings suggest that the water drinking test could be used to determine IOP peaks, as well as for determining baseline IOP.