to corroborate these findings Nutritional optic neuropathies Nutritional deficiency may be the cause of a genuine optic neuropathy, sometimes associated with involvement of the peripheral nervous system, called peripheral neuropathy. Loss of vision is usually bilateral, painless, chronic, insidious and slowly progressive. Most often, they present as a non-specific retrobulbar optic neuropathy. Patients may notice that colors are not as vivid or bright as before and that the color red is washed out. This normally occurs in both eyes at the same time and is not associated with any eye pain. They might initially notice a blur or fog, followed by a drop in vision. While vision loss may be rapid, progression to blindness is unusual. These patients tend to have blind spots in the center of their vision with preserved peripheral vision. In most cases, the pupils continue to respond normally to light. Again, the pathophysiological mechanisms involved in nutritional optic neuropathies is common to all mitochondrial optic neuropathies: it affects biochemical pathways involved in cell energetic production, correction of oxidative stress and quenching of free radicals. Specific deficiencies of cyanocobalamin, thiamine, riboflavin, niacin, and pyridoxine, folic acid, and other proteins with sulfur-containing amino acids may play a role. Months of depletion are usually necessary to deplete body stores of most nutrients and a nutritional optic neuropathy may be present in a patient with or without obvious evidence of under-nutrition. An individual suffering from starvation could be easily recognized as a person who is undernourished due to their cachectic corporal appearance. However, a not so obvious individual may be the recipient of a gastric bypass surgery, a procedure that may lead to vitamin B12 deficiency from poor absorption. The optic neuropathy associated with pernicious anemia and vitamin B12 deficiency can be seen amongst individuals who obtain adequate caloric input from foods low in nutritional and micronutrient density (see Food desert). Additionally, nutrient-poor diet may also be low in anti-oxidants, substances critical to preventing the damaging effects of reactive oxygen species (ROS). ROS are a natural bi-product of the mitochondrial production of ATP. As such, if they are allowed to accumulate without being neutralized, they could damage the very mitochondria from which they are being produced. There is documentation of nutritional optic neuropathy among undernourished Allied prisoners of war of the Japanese during World War II. After four months of food deprivation, some of the prisoners developed sub-acute vision loss