The predominant cause of nutritional optic neuritis is thought to be deficiency of B - complex vitamins, particularly thiamin (vitamin B1) and cyanocobalamin (Vitamin B12). Deficiency of pyridoxin (vitamin B6), niacin (vitamin B3), riboflavin (vitamin B2), and / or folic acid also seems to play a role. Most common visual field defect is central or centrocaecal scotoma.