To assess IOP changes after water drinking test (WDT) in cases with primary congenital glaucoma (PCG).

In this prospective observational study, 20 eyes of 20 patients with PCG were included. Six out of 20 eyes had undergone glaucoma drainage device (GDD) beside the trabeculotomy that all patient had received as the primary surgery. Intraocular pressure (IOP) was measured by an air-puff tonometer at baseline, and at 15, 30, 45, and 60 minutes after WDT. Repeated-Measures ANOVA was used to compare mean IOPs at different time-points.

The mean (±standard deviation) age of participants was 9.9±2.7 years (range, 6 to 16 years) , and 8 (40%) were male. The mean IOPs at baseline, and at 15, 30, 45, and 60 minutes after WDT were 15.8±3.7 mmHg, 18.6±3.4, 19.0±3.8, 17.9±3.8, and 16.9±3.5, respectively (P<0.001). Pairwise comparisons revealed that the mean IOPs at 15 and 30 minutes after WDT were significantly greater than the baseline IOP (P<0.001, and P=0.002, respectively); however, the mean IOPs at 45 and 60 minutes did not. The averages of IOP peak and IOP fluctuation after WDT were 20.0±3.5 and 4.2±2.9, respectively. Although the IOP fluctuation was twice as much as the trabeculotomy values, it was not statistically significant (5.0 vs. 2.5 mmHg; P=0.08).

In patients with PCG, WDT provokes significant IOP elevation at 15 and 30 minutes after the test, which returns to pre-test values at 45 minutes. A trend toward less IOP fluctuation was observed in the GDD group compared with the trabeculotomy group.