A high-pressure situation.

An 8-year-old boy presented with acute visual loss in the right eye and nausea, vomiting, and diplopia. Imaging revealed a right orbital apex mass. Biopsy showed Langerhans cell histiocytosis (LCH), and the patient was diagnosed with isolated orbital LCH causing an orbital apex syndrome. A 12-month cytarabine chemotherapy course was begun, during which the patient developed bilateral optic disc edema. He was diagnosed with cytarabine-induced intracranial hypertension, which was successfully treated with acetazolamide. The cytarabine course was completed with complete resolution of the LCH lesion. The ophthalmologic relevance of this rare disorder is discussed.