Objective: To investigate the effect of trabeculectomy on the intraocular pressure (IOP) fluctuations caused by the postural change in patients with open-angle glaucoma.

Methods: Prospective, nonrandomized study. Ten eyes of 10 patients with primary open-angle glaucoma and 3 eyes of 3 patients with normal-tension glaucoma who underwent trabeculectomy were studied. The IOP at the baseline and 3 months after trabeculectomy was measured in both sitting and supine positions. A pneumatonometer was used to measure the IOP in both sitting and supine position.

Results: The mean IOP in the sitting position was 19.6+/-5.1 mm Hg at the baseline and 9.4+/-2.9 mm Hg after trabeculectomy (P<0.01, paired t test). The mean difference in IOP between the sitting and supine position was 4.1+/-1.6 mm Hg at the baseline and 2.2+/-1.5 mm Hg after trabeculectomy (P=0.01, paired t test).

Conclusions: Trabeculectomy might decrease not only the IOP in the sitting position but also the magnitude of IOP elevation associated with the postural change.