The maximum intraocular pressure from the water drinking test ( 19.74.1 ) was greater than the caffeine test ( 16.74.1 ) and showed greater fluctuation in intraocular pressure ( 4.32.7 mmHg [ 27.7 % ] ; P < 0.0001 ) compared with the caffeine test ( 1.81.9 mmHg [ 11.7 % ] ) ; P = 0.004 ) .