Megaloblastic anemia and bilateral disc edema: An enigma… Have we figured it out yet?

A 28-year-old male presented with insidious-onset, painless, progressive diminution of vision in both eyes. He denied any other ocular symptoms. On examination, visual acuity in both eyes was 6/60. Color vision and contrast sensitivity were maintained in both eyes. Direct ophthalmoscopy revealed that the optic discs were bilaterally hyperemic and congested, with blurring of all the disc margins and loss of spontaneous venous pulsations. Besides this bilateral disc edema, rest of the clinical examination was normal. Primary intensive search for any intracranial space-occupying lesions returned negative on computed tomography scan imaging. Blood investigations revealed a hemoglobin level of 9.2 g/dl, leukocyte count of 7000 cells/mm, and serum Vitamin B12 level of 155 pg/ml (200-835 pg/ml). Serum homocysteine and methylmalonic acid levels were done and were found to be elevated. After 4 weeks, visual acuity improved to 6/6 in both the eyes, and laboratory investigations showed no signs of Vitamin B12 deficiency. Nonsurgical causes for papilledema should be considered in the differential diagnosis. Early diagnosis and prompt treatment is the key to a good prognosis in Vitamin B12-deficient optic neuropathy, which has shown to have a good prognosis if treatment is initiated in the first few months after the onset of symptoms.