Medically controlled glaucoma patients show greater increase in intraocular pressure than surgically controlled...

To evaluate whether patients who have undergone trabeculectomy with mitomycin C have a different intraocular pressure (IOP) response profile after the water drinking test (WDT) from that of patients who are medically managed with a similar baseline IOP and level of visual field (VF) damage.

Prospective observational study.

Thirty glaucoma patients with IOP controlled by trabeculectomy and 30 with medically treated glaucoma matched for level of VF damage and IOP at baseline (7-14 mmHg).

All patients underwent the WDT, which involved drinking 1000 ml of water in 15 minutes.

The IOP was measured before the WDT and subsequently at 15-minute intervals for 1 hour. The peak IOP with the WDT was compared between both groups using Tukey post hoc multiple comparison and paired t tests.

Baseline IOPs were 10.4+/-2.3 mmHg in surgically treated and 11.1+/-1.8 mmHg (P = 0.07) in medically treated eyes. After the WDT, mean IOPs in the surgically and medically treated groups were 10.7+/-2.3 mmHg and 14.6+/-2.2 mmHg. Mean maximum IOPs were 11.7+/-2.6 mmHg and 17.3+/-2.7 mmHg in the surgically and medically treated groups, respectively (P<0.0001), increases of 12.5% and 56%. Ranges of IOP during the WDT were 2.2+/-1.3 mmHg and 5.6+/-1.9 mmHg in the surgically and medically treated patients (P<0.0001).

Patients with advanced glaucoma who are medically controlled show greater IOP elevation and peak IOP after the WDT than eyes that have undergone trabeculectomy.