 More compounds in this class are being investigated in phase 2 and phase 3 trials.A 2013 Cochrane Systematic Review compared the effect of brimonidine and timolol in slowing the progression of open angle glaucoma in adult participants.The results showed that participants assigned to brimonidine showed less visual field progression that those assigned to timolol, though the results were not significant, given the heavy loss-to-followup and limited evidence.