[Mydriasis caused by plant contact]

Abstract

Uni- or bilateral dilatation of pupils that are not reactive to light and lack miosis in response to 1% pilocarpine may be caused by contact with plants containing alkaloids such as scopolamine and atropine. Other causes of a non-light-reactive dilated pupil, such as Adie's tonic pupil, third nerve palsy and lesion of the mesencephalic pretectal region, must be excluded before testing the iris sphincter reaction to 1% pilocarpine. Among the naturally growing flowers in Germany, deadly nightshade (Atropa belladonna), jimson weed (thornapple, Datura stramonium) and black henbane (Hyoscyamus niger) contain enough alkaloids to cause mydriasis by direct contact. However, in most cases an accidental mydriasis by plants in Germany is caused by Datura arborea taxa, e.g. Datura suaveolens, D. candida, D. aurea and D. sanguinea. They contain up to 0.6% dry weight scopolamine. These plants can grow very large and are often planted in tubs. They have to be cut back each year before the winter. This is typically how the eye is contaminated by parts of the plants, which can cause dilatation of the pupil mimicing a neuroophthalmological disorder.