LAUSR

The water‐drinking test (WDT) is known to increase the IOP by approximately 1–2 mm Hg from baseline in healthy adults and by 3–5 mm Hg (~30% of baseline) in treated glaucoma patients.[1,2] Although the exact mechanism of this is unclear (increased episcleral venous pressure or expansion of choroidal volume), the ability of the eye to recover would depend on the aqueous outflow facility. The WDT may be an indirect evaluation of the aqueous outflow capacity.[2] Reports of lower WDT‐IOP peaks in patients treated with prostaglandin analogs add credence to this observation.[2,3] Another prospective study reported a strong correlation between IOP peaks during the WDT and modified diurnal tension curve (r = 0.780, P < 0.0001) in POAG patients without anti‐glaucoma medication.[4] This study demonstrates its utility in predicting the diurnal IOP change as performing a modified diurnal tension curve is labor‐intensive. The water‐drinking test has also been found to cause other short‐term ocular changes besides IOP rise. Read et al.[1] reported significant increases in the IOP and ocular pulse amplitude and a decrease in the axial length (due to a nonsignificant increase noted in choroidal thickness?), the change being more significant among myopes. This indicates a broader ocular change occurring due to hydration requiring further evaluation.