Brimonidine tartrate (BT) (Alphagan) is an α-2 adrenergic agonist marketed for treatment of primary open angle glaucoma (POAG) which may have neuroprotective effects.1 One report of acute delusional psychosis with auditory hallucinations in a 68 year old man treated for POAG has been published,2 and use of BT eye drops in an infant resulted in coma and other serious systemic abnormalities.3 Here we report four elderly patients with bilateral visual loss who developed formed visual hallucinations (Charles Bonnet syndrome; CBS) shortly after beginning the use of BT eye drops. The hallucinations ceased after discontinuation of BT drops in three cases, and after decreasing the dose in one case, within a time frame of days to 4 months. Table 1 summarises visual …