A RARE CAUSE OF UNILATERAL MYDRIASIS: ADIE'S PUPIL

Introduction: Adie's tonic pupil is a benign neuro-ophthalmological condition caused by postganglionic parasympathetic denervation of the ciliary ganglion or short ciliary nerves. It predominantly affects young women and presents as unilateral mydriasis with loss of the light reflex and a tonic response to accommodation. Although the prognosis is favorable, accurate diagnosis is essential to rule out potentially serious neurological causes, particularly third cranial nerve palsy.
Methods: We report the case of a 19-year-old female patient with no significant medical history, presenting with visual discomfort without decreased visual acuity. A complete ophthalmologic and neurological examination was performed, along with an etiological work-up including brain CT and viral serologies. The diagnosis was confirmed using a diluted pilocarpine test (0.125%).
Results: Examination revealed anisocoria, with a dilated right pupil unresponsive to direct and consensual light and showing a tonic response to accommodation; the left pupil was normal. Brain CT, viral serologies, and neurological examination were unremarkable, with no third cranial nerve involvement and preserved osteotendinous reflexes. Instillation of diluted pilocarpine produced selective constriction of the right pupil, confirming denervation supersensitivity and establishing the diagnosis of unilateral right Adie's tonic pupil. No specific treatment was initiated, and the clinical course was favorable, with progressive resolution of symptoms and preserved visual acuity.
Discussion/Conclusion: This case illustrates the typical clinical and pharmacological features of Adie's tonic pupil and confirms the diagnostic value of the diluted pilocarpine test. Recognizing this condition allows unnecessary investigations to be avoided and patients to be reassured, given the generally favorable, self-limited prognosis associated with this disorder.