Adie's tonic pupil is a benign condition supposed to be due to a damage of the parasympathetic innervation of the eye. It may cause considerable anxiety in the patient and lead to extensive but futile investigations. Here, we describe a 34-year-old dermatologist who developed a tonic pupil just after she had started to use intensively a 6 light-emitting diode dermatoscope. We hypothesize that frequent, repetitive exposures of one eye to intense light might fatigue the pupillary reflex and trigger the appearance of a tonic pupil.