Ocular perfusion pressure and visual field indice modifications induced by alpha-agonist compound (clonidine 0.125%, apraclonidine 1.0% and brimonidine 0.2%) topical administration. An acute study on primary open-angle glaucoma patients.

OBJECTIVE

The aim of this study was to verify the acute effects of alpha-adrenoreceptor agonist eyedrop administration on visual field parameters and ocular perfusion pressure (OPP) in patients affected by primary open-angle glaucoma.

METHODS

A prospective, randomized double-blind study was carried out. Sixty-four glaucomatous subjects were enrolled in the clinical trial and subsequently separated into four study groups, of 16 patients each, to compare the systemic and ocular effects of placebo, clonidine 0.125%, apraclonidine 1.0% and brimonidine 0.2%.

RESULTS

No significant variations in the ocular or systemic parameters were observed after placebo administration. All the alpha-adrenoreceptor agonist compounds induced a significant reduction of the intraocular pressure. Clonidine induced significant modifications of mean blood pressure, OPP and visual field indices. The acute administration of apraclonidine did not affect both mean blood pressure and OPP, but a worsening of the visual field was nevertheless recorded. The analyzed parameters did not significantly vary after brimonidine instillation.

CONCLUSIONS

The present findings demonstrate that the lack of effects on the blood flow and the absence of vasomotor activity at the level of the posterior pole exhibited by brimonidine is related to its alpha-2 selectivity, as appears by comparing this compound with the other alpha-agonists available for the management of glaucoma.