Abstract
Purpose: :
The water-drinking test (WDT) has been proposed as a stress test to evaluate intraocular pressure (IOP) elevation in glaucomatous patients and suspects. The purpose of this study was to determine if the time needed to return to baseline levels after the IOP rise was related to its peak in patients diagnosed with or suspected of primary open angle glaucoma (POAG).
Methods: :
Eighty nine eyes of fifty-five individuals underwent the WDT. Of these, 29 (32.6%) were not using any treatment, and 60 (67.4%) were using hypotensive drops. After baseline IOP measurement, all individuals underwent WDT by rinking 1L of bottled water in 5 minutes. IOP measurements were taken at 15, 30, 45, and 60 minutes after ingestion of the water. The main outcomes measured were the peak IOP, time to reach the peak IOP, minimum IOP and time to return to baseline IOP.
Results: :
The mean baseline IOP for the WDT was 14.4 ± 3.6 mmHg (range 7 to 27 mmHg), whereas the mean IOP peak was 18.9 ± 6.1 mmHg. The rise relative to the baseline IOP was in average 20.9 ± 16.5% (range from 0 to 61.5%) for those without treatment and 20.9 ± 15.2% (range from 5 to 71.4%) for those under treatment. Three eyes, which were not using any medication, showed no increase in IOP after the water ingestion and were excluded from further analyses. From the remaining, 26 (29.2%) eyes were back to baseline levels 15 minutes after the peak, 11 eyes (12.4%) 30 minutes after the peak, 17 eyes (19.1%) at 45 minutes, and 29 (32.6%) after 60 minutes. Six eyes did not return to its baseline IOP until the 60 minute measurement. In addition, in 52 eyes the IOP reduced to levels below the baseline (average - 2.00 ± 1.1 mmHg lower). There was a significant association between the IOP elevation (in %) and the ability to return to baseline (P=0.002): the average IOP increase was 16.9% for those whose IOP decreased below baseline during the test, 24.5% for those whose IOP returned just to baseline and 37.2% for those who failed to return to baseline.
Conclusions: :
We observed varied response in regards to the ability to return to baseline IOP levels during a 60 minute WDT. In addition, we observed that in some eyes the response to the WDT is associated with IOP levels that go lower than the baseline. Finally, the increase in IOP is significantly associated with the ability to return to baseline. Further studies should investigate if these parameters are associated with worse prognosis.
Keywords: intraocular pressure • outflow: trabecular meshwork • optic nerve