A case of benign episodic mydriasis

Abstract

Introduction: Anisocoria requires exclusion of serious neurological pathology but it may also be a benign and self – limiting condition, as in cholinergic blockade of the pupillary sphincter by parasympatheticolytic substances or in rare conditions such as benign episodic mydriasis. Case description: A 22 year-old male farm worker presented in June 2014 with decreased visual acuity and ‘foggy vision’ in the right eye. There was no history of contact with toxins. Examination revealed unilateral mydriasis of the right pupil and decrease in the pupillary light reflex and in the ipsilateral accommodation - convergence reflex. No changes were noted in extra-ocular movements or in the position of the eyelids. No other abnormalities were found on physical examination. The patient was referred to the Ophthalmology Emergency Department where he underwent further examination that did not reveal additional findings. Comment: A negative history of contact with toxins, the absence of other neurological signs or symptoms, and a normal magnetic resonance angiography study support a diagnosis of benign episodic mydriasis. This is a rare condition, which appears to be related to autonomic dysfunction. It is important for family physicians to be aware of this condition, to know how to perform a correct clinical examination, and to refer the patient for additional testing to exclude other diagnoses. Patients require reassurance that the condition is benign and proper follow-up for possible recurrence.