“…Regarding intrinsic chiasmal lesions, neoplasm [3,[5][6][7], chiasmal infarction [3,8,9], sarcoidosis [3,10], and OCN [1,3,[11][12][13][14][15][16][17][18][19] have been reported. Among them, OCN is a relatively rare symptom consisting of acute visual loss due to chiasmal infl ammation [1,3,[11][12][13][14][15][16][17][18][19], and commonly occurs as an idiopathic event, either in isolation or in the setting of multiple sclerosis [3,11]. Furthermore, previous reports have noted that VZV infection, infectious mononucleosis due to EBV [12], CMV infection [13], mumps parotitis [14], Lyme disease [15], neuromyelitis optica [16], systemic lupus erythematosus [17], vitamin B12 defi ciency [18], and ethchlorvynol toxicity [19] might induce OCN.…”