Acute and chronic effects of brimonidine 0.2% on intraocular pressure and pulsatile ocular blood flow in patients with primary open-angle glaucoma: An open-label, uncontrolled, prospective study

Background. Brimonidine has been reported to decrease aqueous production and increase uveoscleral outflow; however, the hemodynamic effects of brimonidine are still under investigation. Objective: The purpose of this study was to report the acute and chronic effects of brimonidine 0.2% on intraocular pressure (IOP) and pulsatile ocular blood flow (pOBF) in patients with primary open-angle glaucoma (POAG). Methods: Nonsmoking patients aged 45 to 67 years with POAG and normal blood pressure, heart rate, body mass index, and hemorheologic parameters were enrolled in the study. Brimonidine 0.2% was self-administered twice daily for 180 days. IOP and pOBF were determined using Goldmann applanation tonometry and the Langham system. All measurements were taken at baseline and 4, 8, and 12 hours after treatment and were repeated on days 7, 15, 30, 60, 90, 120, 150, and 180 of treatment. Results: Of the 18 eligible patients, 10 (6 men and 4 women) were enrolled (mean age, 51.5 +/-4.39; range, 47-64 years). When measured 12 hours after instillation, mean IOP was significantly reduced by 21.5% (P<0.001) compared with the baseline value. The greatest decrease in IOP (-23.5%) was observed at 8 hours. After 12 hours, a significant increase (P<0.001) in pOBF was measured. A stable IOP reduction (P<0.001 vs baseline), as well as an increase in pOBF (P=0.015), was recorded at the subsequent time points. The pOBF increases ranged from 22.5% at day 30 to 9.2% at day 180 of treatment. No evidence of adverse events was found at any time point. Conclusions: In this sample of patients with open-angle glaucoma, brimonidine induced a rapid reduction in IOP that was significant even after 6 months. Moreover, an increase in pOBF was observed from the first day of treatment, and remained consistent throughout the study.