Zinc deficiency, acrodermatitis enteropathica, optic atrophy, subacute myelo-optic neuropathy, and 5,7-dihalo-8-quinolinols.

Acrodermatitis enteropathica, a heritable disease of zinc deficiency, was formerly amenable to treatment only with dihaloquinolinol drugs. A few cases of optic atrophy were reported in surviving patients and were proposed as examples of ocular drug toxicity, principally because of the association between iodochlorhydroxyquin and subacute myelo-optic neuropathy (SMON) in Japan. An alternate hypothesis is now offered: that the optic atrophy was secondary to the zinc deficiency, which is consistent with diverse evidence cited from the literature. Therefore, it would seem worthwhile to investigate zinc in cases of disk pallor described as idiopathic or drug associated, and to investigate visual function in cases of severe malnourishment.