Neurovascular Changes Associated With the Water Drinking Test.

Abstract

The water drinking test (WDT) is currently used to temporarily elevate intraocular pressure (IOP) and predict peak IOP in glaucoma. This study investigates neurovascular changes associated with WDT in normal subjects. The effect of WDT (1 L in 5 min) on IOP, mean brachial blood pressure, heart rate, and pattern electroretinogram was assessed within the next hour in 16 healthy subjects (mean age: 33.5±7.9 y). As a control, testing was repeated in the same subjects without WDT 1 week later. Compared with control, WDT resulted in significant peak changes of the following parameters compared with baseline: IOP: +1.7±1.8 mm Hg after 30', mean brachial blood pressure: +3.9±6.3 mm Hg after 15'; heart rate: -9.2±9.8 bpm after 15', pattern electroretinogram latency: +2.1±0.9 ms after 15'. In addition to IOP elevation, WDT was associated with significant changes of hemodynamic parameters and retinal ganglion cell function in young healthy subjects. As these represent risk factors for glaucoma, their assessment upon WDT might increase its predictive power for glaucoma development.