A O’Shea

An acute-onset, unilaterally fixed mydriasis can be a sign of life-threatening intracranial pathology e.g. intracranial bleed, but can also be due to more benign causes. We present a case of a healthy 46-year-old ICU nurse who developed an acute-onset unilateral mydriasis secondary to the accidental inoculation of her eye with hyoscine from a scopolamine patch she’d applied to a doctor for motion sickness. Due to the association of life-threatening intracranial pathology with a fixed mydriatic pupil, it is important to differentiate between pharmacologically-induced and pathological anisocoria. In this instance, the concern to exclude intracranial pathology can often lead to a plethora of unnecessary investigations and significant patient anxiety.