Four criteria are used to evaluate the potential usefulness of an agent for neuroprotection in
glaucoma: 1) the agent must have a target in the retina; 2) it must be neuroprotective in
animal models; 3) it must reach neuroprotective concentrations in the posterior segment
after clinical dosing; and finally, 4) it must be shown to be neuroprotective in clinical trials.
The alpha-2 adrenergic agonist brimonidine has met the first three criteria and clinical trials
to establish the fulfillment of the fourth criterion are ongoing. The effects of brimonidine are …