The Optic Neuropathy of Pernicious Anemia

The high incidence of pernicious anemia (PA) among patients presenting with tobacco amblyopia is noted. Four patients with PA, two of whom presented initially with visual loss indistinguishable from tobacco amblyopia, and two of whom developed similar symptoms while on treatment with cyanocobalamin are described. In all four cases, the hemopoietic abnormality was restored to normal on treatment with cyanocobalamin, but visual improvement did not occur until treatment was changed to hydroxocobalamin. The significance of these findings is discussed.