Reproducibility of intraocular pressure peak and fluctuation of the water-drinking test

Abstract

Background The water-drinking test has been used as a stress test to evaluate the drainage system of the eye. However, in order to be clinically applicable,a test must provide reproducible results with consistent measurements. This study was performed to verify the reproducibility of intraocular pressure peaks and fluctuation detected during the water-drinking test in patients with ocular hypertension and open-angle glaucoma. Design A prospective analysis of patients in a tertiary care unit for glaucoma treatment. Participants Twenty-four ocular hypertension and 64 open-angle glaucoma patients not under treatment. Methods The water-drinking test was performed in 2 consecutive days by the same examiners in patients not under treatment. Reproducibility was assessed using the intraclass correlation coefficient. Main Outcome Measures Peak and fluctuation of intraocular pressure obtained with the water-drinking test were analysed for reproducibility. Results Eighty-eight eyes from 24 ocular hypertension and 64 open-angle glaucoma patients not under treatment were evaluated. Test and retest intraocular pressure peak values were 28.38 +/- 4.64 and 28.38 +/- 4.56mmHg, respectively (P=1.00). Test and retest intraocular pressure fluctuation values were 5.75 +/- 3.9 and 4.99 +/- 2.7mmHg, respectively (P=0.06). Based on intraclass coefficient, reproducibility was excellent for peak intraocular pressure (intraclass correlation coefficient=0.79) and fair for intraocular pressure fluctuation (intraclass correlation coefficient=0.37). Conclusion Intraocular pressure peaks detected during the water-drinking test presented excellent reproducibility, whereas the reproducibility of fluctuation was considered fair.