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R. M. Vessani, M. Babic, R. Susanna; Comparison of Water Drinking Test and Ibopamine Test in Primary Open Angle Glaucoma Patients. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1271.
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Ibopamine test and water drinking test (WDT)are provocative methods leading to transient increase of IOP. This study evaluated both tests in primary open angle glaucoma (POAG) patients to assess the interchangeability of results.
Charts from consecutive patients with POAG submitted to WDT and ibopamine test in the same day were reviewed. All subjects were under clinical therapy. True agreement between methods in measuring IOP peak was assessed using Bland-Altman graphs. IOP variation with either test was divided into three equally-numbered tertiles and classified as "A" (IOP variation ≤ 3 mmHg), "B" (3 mmHg < IOP variation ≤ 6 mmHg) and "C" (IOP variation > 6 mmHg) and agreement between methods in this classification was assessed using Κ statistics.
Fifty-five eyes of 55 primary open angle glaucoma patients were included in this study (32 women, 23 men, mean age = 61.68 ± 13.66 years). No significant differences were observed in baseline IOP before each test . Figure shows Bland-Altman plots of the agreement in IOP peaks between WDT and ibopamine test. The difference (WDT IOP peak - Ibopamine test IOP peak) was plotted against the average of the two measurements for IOP peak. The inspection of the scatterplot reveals a considerable discrepancy between the IOP measurements obtained by the two methods. The 90% confidence interval for IOP peak difference was between 6.7 mmHg and -6.6 mmHg. 49% of the eyes demonstrated higher IOP peak with ibopamine test compared to WDT. The opposite was observed in 40% of the studied eyes. In 45.3% of the studied eyes, the IOP peak difference between the two tests was higher than 2 mmHg.
Results obtained with water drinking test and ibopamine test were not the same in the majority of primary open angle glaucoma patients of this study. Our findings suggest that these tests are not interchangeable, despite the fact that they are provocative methods.
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