Effect of brimonidine on intraocular pressure in normal tension glaucoma: a short term clinical trial

To evaluate the efficacy and safety of 0.2% brimonidine eye drops given twice daily in normal tension glaucoma.

Sixteen consecutive patients fulfilling eligibility criteria (glaucomatous optic neuropathy associated with visual field defect in at least one eye, intraocular pressure (IOP) < or = 18 mmHg (average of the two highest readings of the round-the-clock curve, including one reading at midnight in supine position), no prior glaucoma therapy, angle wide open, visual acuity 20/40 or better) were enrolled in this prospective, randomized, placebo-controlled clinical trial with crossover design, lasting 30 days for each treatment phase plus 15-day washout in between. Main outcome was IOP (average of the two highest readings of the round-the-clock curve).

Mean IOP was significantly reduced by brimonidine (from 17.1 +/- 0.7 mm Hg to 13.9 +/- 2.2 mmHg, p<0.001 (paired Student t-test)). At the end of the 30-day brimonidine phase, 4 of 16 subjects showed a > or = 30% IOP decrease over baseline.

In the short term, 0.2% brimonidine eye drops can induce a significant IOP decrease in eyes with normal tension glaucoma.