Effect of brimonidine on anterior-chamber angle in patients with narrow angles .

Methods
Nine eyes with narrow angles were distributed to one of three treatment groups--single topical dose of 0.15% brimonidine tartrate, 0.5% timolol
maleate (positive control), or balanced salt solution (negative control)--in a prospective, single-masked, crossover, comparative trial. The primary outcome measure was anterior-chamber angle at baseline, and 2 and 4 hours after instillation of the treatment drug. Secondary outcome measures were pupil diameter, intraocular pressure (IOP), and anterior-chamber depth and volume. After a two-week washout period, eyes were crossed over to the other treatment modes. All baseline and posttreatment measurements were taken. Repeated analysis of variance (ANOVA) was used for statistical analysis.

Results
Anterior-chamber angle, depth, and volume did not differ significantly for all treatment groups. Brimonidine caused a significant decrease in pupil
diameter, most notably 2 hours after instillation, from baseline of 2.36 ± 0.37 mm to 2.17 ± 0.35 mm. (p = 0.03). There was a significant decrease in IOP from baseline to hour 4 after treatment for both brimonidine (11.4 ± 2.2 to 9 ± 1.8 mm Hg, p < 0.001) and timolol (11.9 ± 2.3 to 9.4 ± 2.1 mm Hg, p = 0.003).

Conclusion
Brimonidine produced a miotic trend with no significant opening of the anterior-chamber angle in patients with narrow angles.