Unilateral mydriasis due to hemorrhoidal ointment

The finding of a unilaterally dilatated pupil in a patient who is otherwise alert and unimpaired can pose an interesting diagnostic problem. Algorithms have outlined the approach to evaluating anisocoria, but do not stress the importance of toxic exposures.

A patient with a history of depression and chronic headaches was referred to the emergency department from an ophthalmologist's clinic with the findings of asymmetrically dilatated pupils and blurred vision. Detailed history revealed that for several weeks before the onset of symptoms, the patient applied to her eyelids hemorrhoidal ointment that contained an active ingredient known to produce mydriasis.

In the absence of neurologic deficits, clinical history should search for a toxic or pharmacologic etiology of abnormal mydriasis. A detailed physical examination and bedside diagnostic maneuvers can help distinguish benign causes of an abnormally dilatated pupil from more serious causes relating to central nervous system lesions, potentially sparing the patient from unnecessary neuroimaging.