<p>Brimonidine is an alpha-2 adrenoreceptor agonist that is more selective for the alpha-2 adrenoreceptor than alpha-1. Topical administration of low concentration of Brimonidine Tartrate eye drops reduces ocular redness in humans by constricting the venule, alleviating the potential decrease of blood and oxygen through the eye. It has minimal to no activity on the alpha-1 receptor, which has a low risk of redness rebound of loss of efficacy over time when used as directed.</p>