Effects of acute topical administration of clonidine 0.125%, apraclonidine 1.0% and brimonidine 0.2% on visual field parameters and ocular perfusion pressure in patients with primary open-angle glaucoma

A prospective, randomized double-blind study has been carried out to verify the acute effects of -adrenoreceptor agonist eyedrops administration on visual field parameters and ocular perfusion pressure in patients affected by primary open-angle glaucoma. Thirty-two glaucomatous subjects (64 eyes) were enrolled in the clinical trial and subsequently randomized into four study groups to compare the systemic and ocular effects of placebo, clonidine 0.125%, apraclonidine 1.0% and brimonidine 0.2%. No significant variations in the ocular or systemic parameters were observed after placebo administration. All the -adrenoreceptor agonist compounds induced a significant reduction of the intraocular pressure (p<0.01). Only the acute administration of clonidine 0.125% resulted in a decrease in ocular perfusion pressure (p<0.001). Both clonidine 0.125% and apraclonidine 1.0% caused a significant worsening of visual field parameters. On the contrary, topical brimonidine 0.2% did not induce any significant visual field modification, suggesting that its acute administration does not affect the blood flow or vasomotor activity at the level of the posterior pole.