Hunt and colleagues highlight various aspects of B12 deficiency in this engaging and valuable review article(1). An important but often overlooked aspect of B12 deficiency is the associated retinal damage. Considerable evidence explores that people with compromised B12 levels are more susceptible to development of age related macular degeneration (AMD) and the prevalence is much reduced in those taking cobalamine supplementation(2). B12 deficiency could also manifest itself as optic neuropathy and present as progressive decline in visual acuity leading to gradual development of bilateral centocecal scotomas(3).
Health care workers need to consider the fact that widespread use of folic acid supplements and food fortification practice can significantly diminish the haematological effects of B12 deficiency(4), and further exhibit a “masking effect” on the detection of retinal symptoms. This may act as a major ground for concealed and irreversible progression of the retinal loss, especially in older persons. Perhaps what we need is a much closer attention on retinal and neurological symptoms in suspected cases of B12 deficiency.
1. Hunt A, Harrington D, Robinson S. Vitamin B12 deficiency. BMJ 2014;349:g5226 doi: 10.1136/bmj.g5226.
2. Gopinath B, Flood V, Rochtchina E, Wang J, Mitchell P. Homocysteine, folate, vitamin B-12, and 10-y incidence of age-related macular degeneration. Am J Clin Nutr 2013; 98:129-135.
3. Chavala S, Kosmorsky G, Lee M, Lee M. Optic neuropathy in vitamin B12 deficiency. Eur J Int Med 2005; 16:447–448.
4. Reynolds E. Vitamin B12, folic acid, and the nervous system. Lancet Neurol.2006; 5:949–960.
Competing interests: No competing interests