A number of plants can cause mydriasis following exposure.
Exposures may be:
(1) topical (rubbing into eye)
(2) oral ingestion
(3) smoke inhalation (if burned)
Clinical features:
(1) presence of fixed mydriasis and blurred vision
(2) recent exposure to a plant associated with mydriasis
(3) exclusion of other explanations for the mydriasis
(4) variable systemic symptoms (with systemic absorption), such as tachycardia
Plants causing parasympathetic palsy (antagonist):
(1) Amanita pantherina (active ingredients muscimol and ibotenic acid)
(2) Solanum species (black nightshade, woody nightshade; active ingredients solanine and solanidine)
(3) Datura species (active ingredients atropine, hyoscyamine, scopolamine)
Plants causing sympathetic activity:
(1) Amanita muscaria
(2) Catha edulis (khat, bushman tea; active ingredient cathione)
Plants with unknown mechanism:
(1) Chenopodium oil (American wormseed oil)
(2) Lolium temulentum
(3) Lupin seed
(4) Strychnos (strychnine, brucine)
Exposure to Datura species can be confirmed using a 1% pilocarpine eyedrop in the affected eye. Atropine in the Datura competitively inhibits the effects of the pilocarpine.
