Vitamin B-12 -- also known as cobalamin -- is a member of the B vitamin family; this nutrient helps in the formation of red blood cells and is important in nervous system function. You can get B-12 in animal-based products like meats, fish and dairy products; people who do not eat these types of foods may need B-12 supplements to avoid a nutritional deficiency. B-12 deficiencies can cause multiple health issues, including problems with vision.
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Optic neuropathy -- damage to the optic nerve -- can lead to vision loss and can be caused by a variety of issues. Since vitamin B-12 plays a role in the function of nerves and the nervous system, a deficiency in this vitamin can lead to optic neuropathy and decreased vision. S.H. Chavala and colleagues found that supplementation of B-12 improved the symptoms of optic neuropathy in specific cases. A recent case report by Stacy L. Pineles and colleagues published in the journal "Pediatrics" found that several children with autism who did not eat animal products developed optic neuropathy caused by a vitamin B-12 deficiency. Treating these children with B-12 reversed the vision problems. Vitamin B-12 deficiency may be a cause of vision loss in people who may be suffering from malnutrition or who do not consume many animal products.
Glaucoma is a form of optic neuropathy in which the optic nerve is damaged by the pressure in the eye. Eye doctors treat patients who have glaucoma with medications or surgeries to lower the eye pressure, but research is ongoing to find other types of therapies to manage the condition. Some researchers have found that treating glaucoma patients with extra amounts of B-12 may decrease the amount of vision loss and stabilize the visual acuity of these people. Dr. Yoshio Yamazaki and colleagues treated the patients with 1,500 mcg of B-12 every day for four years and determined that this supplement may be helpful in treating glaucoma. Additional research is needed.
Age-Related Macular Degeneration
The retina is a nerve layer in the back of the eye that helps process visual images. In the disease age-related macular degeneration, the center of the retina is damaged; this condition typically affects older adults and has no cure. Treatments are available for the vision loss, but researchers are looking for ways to prevent the development of the disease in the first place. A study by William G. Christen and colleagues found that a combination of B vitamins -- folate, B-6 and B-12 -- taken daily may lower the risk of developing macular degeneration in women. The reason for this finding is not fully understood, but it is another example in which increasing the intake of vitamin B-12 may have an impact on improving vision.
As we get older, the lens inside the eye can become cloudy and cause decreased visual acuity. This cloudy lens, or cataract, can be removed and replaced with an artificial lens; cataract surgery is a common surgical procedure in the United States. Finding a substance that may slow down or stop the development of cataracts is an important area of interest; a study published in the July 2001 issue of "American Journal of Ophthalmology" looked at the use of different vitamins and their effect on cataracts. Maciek Kuzniarz and colleagues found that long-term use of B-12 supplements decreases the risk of a specific change called a cortical cataract.