June 5, 2017 E-Pearl of the Week: Pharmacologic pupil: The “blown pupil” of a healthy patient

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June 5, 2017

Pharmacologic pupil: The “blown pupil” of a healthy patient

Medications are a common benign cause of unilateral mydriasis. In the outpatient setting, finger-to-eye contact involving scopolamine patches, glycopyrrolate cream, or certain plants (e.g. Jimson weed) are frequent causes. Nebulized ipratropium escaping through an ill-fitted mask is common in inpatients with respiratory distress.  The use of pilocarpine, a muscarinic agonist, can be helpful in diagnosis. Occupation of muscarinic acetylcholine receptors will prevent constriction of the mydriatic pupil in response to the instillation of 0.1% pilocarpine, which suggests benign rather than dangerous causes (e.g. compressive oculomotor palsy). Often, in patients without other neurologic findings, careful observation may be sufficient to ensure return of pupillary function.


  1. Moeller J, Maxner C. The Dilated Pupil: An Update. Current neurology and Neuroscience Reports 2007; 7: 417-422.

Submitted by Stephen Aradi, MD - Neurology Resident, University of Pennsylvania. 

Dr. Aradi reports no disclosures.

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