Modern Pupillometry

Pupillometry, the study of the eyes’ pupils, has a rich history, dating back to the 1800s.  For example, to appear “dark with desire,” women once used atropa belladonna (deadly nightshade) as a cosmetic, because the atropine dilated their pupils, making them appear more romantically aroused. We now know that this relationship is largely driven by the activity of the sympathetic nervous system; specifically, a small brainstem nucleus known as the locus coeruleus (LC). Because of tight connec