Chronic relapsing inflammatory optic neuropathy (CRION) is an uncommon cause of visual loss that is at the same time a common cause of frustration to the neuro-ophthalmologist. As suggested by its appellation, CRION is an optic neuropathy with inflammatory features (pain, response to corticosteroids) that relapses when corticosteroids are withdrawn. This occurs chronically over months to years. When a specific etiology is found, such as similarlybehaving sarcoidosis, by definition CRION is not present.
Spencer S. Eccles Health Sciences Library, University of Utah