Tuan Tran, Nuwan Niyaduropola, Jeremy O’Connor,Ghee Soon Ang, Jonathan Crowston, Dan Nguyen
There is increasing emphasis on the impor-tance of intraocular pressure (IOP) peaks and fluctua-tion as risk factors for glaucoma progression. It is wellrecognised that ingesting significant volumes of wateras in the water drinking test (WDT) raises IOP andreasonable evidence that caffeine can also raise IOP.The aim of this study is to directly compare the effect ofa caffeine test (CT) to that of the WDT on IOP inpatients with glaucoma.
Prospective, observer-masked, crossoverstudy of 14 eyes of 14 medically treated patients withprimary open angle glaucoma. Patients were initiallyrandomised to either CT or WDT. IOP was measured inboth eyes with a Goldmann applanation tonometer atbaseline before the test, and after the test, for every 15minutes for 1 hour by a masked examiner. This wasrepeated the following week at the same time of dayfor the other test (the crossover). Peak and fluctuationof IOP were compared between groups using thepaired t-test.
The maximum IOP obtained by the WDT(19.7 ± 4.1) was greater than the CT (16.7 ± 4.1); andshowed greater fluctuation in IOP (4.3 ± 2.7 mmHg[27.7%] p < 0.0001) compared to the CT (1.8 ±1.9 mmHg [11.7%]); p = 0.004).
The mean rise in IOP was greater withthe WDT than the CT. Intake of a 100 mg caffeinatedbeverage does not appear to provide an alternative forpatients unable to tolerate the WDT.