You are correct. The pt had a normal brain MRI and on further questioning mentioned that she grew angel’s trumpet (Brugmansia), a plant known to contain parasympatholytic alkaloids atropine, hyoscyamine, and scopolamine. Accidental exposure to these plants can produce unilateral mydriasis by muscarinic receptor blockade, leading to paralysis of the smooth muscle of the pupillary sphincter and ciliary muscles. Holmes-Adie is a chronic condition, in contrast to the acute onset in this pt. Absence of pain excluded acute angle-closure glaucoma, and there was no evidence of raised intracranial pressure or 3rd nerve palsy. Her anisocoria resolved w/in 72h. This case highlights the importance of taking a detailed hx of chemical exposure in pts presenting w/ mydriasis.

Emergency Medicine Journal 2019;36:201-218.