In extreme cases, lack of B12 can damage the optic nerve or plug up the blood vessels in the retina, causing blurry vision, double vision, sensitivity to light, and even vision loss.
“Vitamin B12 deficiency should be considered in the differential diagnosis of any patient with optic nerve cupping and bitemporal visual field loss,” said The Review of Optometry.
The health site continued: “Risk factors for developing this deficiency include malnutrition, tobacco or alcohol abuse, age and any type of malabsorption disorder.
“Some patients may experience an improvement and partial recovery of visual function after vitamin B12 supplementation.”