Abstract
Purpose: :
To evaluate the reproducibility of the water drinking test performed at different times of the day.
Methods: :
30 patients with primary open angle glaucoma (POAG) and 34 healthy individuals underwent three water drinking tests at different times of the day (8 AM, 12 PM, and 4 PM) on 3 different days. The water drinking test consisted of drinking 1000 ml of water in 5 minutes after fasting for 6 hours. Intraocular pressure (IOP) measurements (Goldmann applanation tonometry) were obtained prior to, 15 minutes, 30 minutes, 45 minutes, and 60 minutes after drinking water. Agreement among IOP baseline levels, peak levels, and IOP change (peak IOP – baseline IOP) at the 3 time intervals was evaluated using the Bland Altman analysis. Test results in POAG patients and healthy individuals were compared.
Results: :
Mean baseline IOP level, peak level and change were significantly higher in POAG patients than in control individuals, at all time intervals (p<0.05). Mean IOP peak levels did not differ significantly at the three time intervals both in POAG patients (p>0.05) and controls (p>0.05). Mean IOP change in the left eye (OS) was significantly higher at 4 PM than at 12 PM both in POAG patients and control individuals (p=0.03). Differences higher than 3 mmHg among IOP peak levels at different tests were found in 41% (OD) and 37 % (OS) of POAG patients and 23 % (OD and OS) of control individuals. Differences higher than 3 mmHg among IOP changes at different tests were found in 50 % (OD) and 34 % (OS) of POAG patients and 13 % (OD) and 27 % (OS) of control individuals. The Bland Altman analysis demonstrated low levels of agreement and large 95% confidence intervals (> 8 mmHg) for IOP peak levels and IOP changes.
Conclusions: :
The IOP peak and change observed during the water drinking test are significantly higher in POAG patients than in control individuals. The results of the water drinking test are highly variable depending on time of the day when it is performed.
Keywords: intraocular pressure • outflow: trabecular meshwork • aqueous