Page "Mydriasis" Paragraph 10

Anticholinergics such as atropine, hyoscyamine, and scopolamine antagonize the muscarinic acetylcholine receptors in the eye.

By blocking these receptors, the pupils are no longer capable of constriction and dilation results.

Such alkaloids present in many plants of the family Solanaceae may also induce mydriasis when used recreationally.