The efficacy of brimonidine in preventing intraocular pressure elevation in the provocative test for primary angle-closure glaucoma

The purpose of this study was to evaluate the efficacy of 0.2% brimonidine tartrate in preventing intraocular pressure (IOP) elevation in the dark-prone provocative test for primary angle-closure glaucoma (PACG). Twenty-two eyes from 22 patients with angle-closure glaucoma were enrolled in this study. Each of the selected eyes had previously tested positive in a recent dark-prone test. One drop of 0.2% brimonidine tartrate was then instilled in each eye 2 hours prior to a second dark-prone test. An IOP elevation of greater than 8 mmHg was regarded as a positive result. The IOP elevation in the first dark-prone test was 11.91 +/- 5.17 (range: 5.7 - 27.3) mmHg, while the IOP only increased 5.70 2.96 (range: 2.9 - 12.2) mmHg in the second dark-prone test that was pre-treated with 0.2% brimonidine tartrate (p < 0.001). A significant difference was also noted in the pretest IOP (15.59 +/- 3.86 mmHg vs. 13.33 +/- 3.65 mmHg, p = 0.008) as well as in the post-test IOP (27.62 +/- 7.27 mmHg vs. 19.03 3.50 mmHg, p < 0.001) in the two sequential dark-prone tests. All but three of the initially positive dark-prone tests (86.46%) converted to negative tests after pre-treatment with brimonidine. There was a significant effect of 0.2% brimonidine tartrate in the prevention of IOP elevation in PACG patients previously found to test positive in the dark-prone provocative test.