Abstract
Purpose :
The water-drinking test (WDT) was abandoned in the late 70's as a diagnostic tool for glaucoma; but has recently re-emerged as a possible way to determine the competency of the trabecular meshwork. We performed a prospective observational study to test the hypothesis that the WDT could be useful in assessing fluctuations in patients undergoing treatment for primary open angle glaucoma (POAG).
Methods :
We included 122 patients; 62 on treatment for POAG (n=123 eyes) and 60 controls (n=120 eyes). The study group had been on IOP lowering treatment continuously for at least three months and presented stable intraocular pressures. Exclusion criteria were non compliance to treatment and any previous glaucoma surgical intervention. The WDT was performed fasting. Intraocular pressure was measured with Goldman tonometer. Following the consumption of 1L of water, pressures were measured every 15 minutes and repeated three times. The test was positive if the fluctuation was ≥ 6mmHg. For statistical significance; Fisher-exact test and t-test were employed.
Results :
The patients on treatment had a mean age of 50.56+/-18.45 years vs 51.35 +/- 11.22 for the controls (p=0.34); with 71% being female. In the study group; 52% used beta blockers (n=64), 27% a combination of two or more medications (n=33), 19% prostaglandin analogues (n=24) and 2% alpha agonists (n=2). The WDT was positive in 17.07% (n=21) in the study group and 2.5% (n=3) in the control group (p=0.0001). The mean fluctuation was 7.14+/-2.15 mmHg in the study group. There was no significant difference (p=0.18) in the mean baseline pressures between the groups that tested positive and negative (12.71+/-3.34 and 12.01+/-1.96 mmHg, respectively) and the controls (12.22+/-1.75 mmHg). As for the female gender; 15% (n=12) tested positive compared to 20.93% (n=9) of male patients (p= 0.27). In the controls, 2.17% of females and 3.57% males were positive (p=0.55). A positive WDT was found in 33.33% (n=11) of those on combination therapy; 12.5% (n=3) of prostaglandin analogues and 10.94% (n=7) of beta blockers (p=0.03). For a negative WDT the mean fluctuation was 2.20+/-1.51 and 1.99+/-1.39 for the controls. Combination therapy had the highest positive WDT fluctuation (7.54+/-2.87) followed by prostaglandin analogues (7.00+/-1.00) and beta blockers (6.57+/-0.78).
Conclusions :
The WDT can identify significant fluctuations in eyes with POAG that are medically treated.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.