Vitamin B 12 absorption in tobacco amblyopia.

It is well established that a proportion of patients with tobacco amblyopia have pernicious anaemia or some other demonstrable defect of vitamin B12 metabolism (Leishman, 195I; Heaton, McCormick, and Freeman, I958; Freeman and Heaton, I96I; Foulds, Chisholm, Bronte-Stewart, and Wilson, I968). We have examined 65 cases of tobacco amblyopia diagnosed according to the criteria of Heaton and others (I958) for evidence of defective vitamin B12 metabolism, with particular reference to vitamin B12 absorption.