• Seventeen patients with primary open-angle glaucoma underwent laser trabeculoplasty. Measurement of fluorescein leakage into the anterior chamber showed significant differences between surgically treated eyes and control eyes (not surgically treated) one day postoperatively and one week postoperatively. The increase in fluorescein leakage probably represents a disruption of the bloodaqueous barrier. In contrast, there were no differences between the eyes preoperatively or one month postoperatively. Hence, the long-term pressure-lowering effects of laser trabeculoplasty do not seem to be related to any permanent change in the blood-aqueous barrier.