Congenital Mydriasis: Diagnostic Challenge in a Case with Accompanying Neurologic Symptoms.

A 34-year-old woman was hospitalised with acute onset nausea, vomiting, ataxia, nystagmus, blurred vision, and bilateral mydriasis. Toxicologic investigations and serologic tests for infectious aetiologies were negative. Demyelinating disease was suspected based on magnetic resonance imaging (MRI) findings but there were no lesions at the midbrain explaining bilateral mydriasis. Direct light, consensual light, and near responses for pupil were all negative. Biomicroscopic examination of the iris did not show any sphincter damage or tonic movements. Pupils didn't respond to pilocarpine (0.1% and 2%) and remained unresponsive during the follow-up period. Congenital mydriasis was diagnosed because old photographs revealed that pupils were dilated previously.