To compare the intraocular pressure (IOP) response after the water drinking test (WDT) in patients who have undergone trabeculectomy or tube shunt surgery.Methods:
This prospective study examined 40 eyes of 34 open-angle glaucoma subjects who had undergone trabeculectomy (n=20) or tube shunt surgery (n=20). Both groups were matched by IOP range and by number of topical antiglaucoma medications used. After a baseline IOP assessment, subjects drank 10 mL water per kg body weight over 15 minutes. IOP was then measured with a Goldman tonometer every 15 minutes over a 1-hour period. Outcomes measures were IOP peak, fluctuation, mean, and range.Results:
No significant differences in baseline demographics, baseline clinical characteristics or IOP changes during the WDT were observed between the 2 surgical procedure groups. Mean baseline IOPs for the tube shunt and trabeculectomy groups were 12.55±4.23 and 12.3±4.28 mm Hg, respectively (P=0.854). In the trabeculectomy and tube shunt groups, respectively, peak IOP was 16.25±5.55 and 16.15±5.36 mm Hg (P=0.954); IOP fluctuation (IOP max—IOP baseline) was 3.95±2.17 and 3.6±2.23 mm Hg (P=0.618), and IOP range was 2.78±1.56 and 2.8±1.47 mm Hg (P=0.959). Statistical analysis of IOP fluctuation associations using multivariable linear regression determined that the use of systemic antihypertensive blood pressure medication was associated with an increase in IOP fluctuation of approximately 2 mm Hg.Conclusions:
Subjects who had undergone either trabeculectomy or tube shunt surgery showed a similar IOP response to the WDT. Subjects on systemic antihypertensive medications experienced significantly greater IOP fluctuations during the test.