Optic neuropathy in a patient with vitamin B12 deficiency: a case report.

A 19-year-old man presented with blurring of vision for 2 weeks. He also complained of anorexia with weight loss during the past 4 months. Eight years ago, his small bowel from midportion of the jejunum, ileum, ascending colon and transverse colon were resected because of gangrene. He gave no history of exposure to tobacco, alcohol or other toxins. The bone marrow aspiration showed hypocellular with panhypoplasia. Serum vitamin B12 level was low while serum and red cell folate were within normal limits. His visual acuity was 5/200 in both eyes with centrocecal scotomas in both eyes. Other neurologic and ophthalmic examinations were found to be normal. The patient was given intramuscular injections of 1,000 micrograms of cyanocobalamin. Four months later, his visual acuity improved, serum vitamin B12 level and the bone marrow returned to be normal. This is a frank case of optic neuropathy in a patient with vitamin B12 deficiency due to a massive small bowel resection.