Vitamin B12 deficiency affecting the optic nerve.
D006801:Humans; D009443:Neuritis / Q000209:etiology*; D009900:Optic Nerve; D009901:Optic Nerve Diseases; D014806:Vitamin B 12 Deficiency / Q000150:complications*
NEURITIS/etiology; OPTIC NERVE/diseases; VITAMIN B 12 DEFICIENCY/complications