The fat-soluble factor, vitamin A, although not yet isolated in pure form and although totally unknown until the last decades, has held the attention of clinicians, through the manifestations of its deficiency, since the earliest times. Night blindness, one of the first symptoms of avitaminosis A, was known to Hippocrates, and the beneficial results of a liver diet in the treatment of this disorder were described by Paul of Aegina.1 The more advanced symptom complex, keratomalacia, was not described until the middle of the last century, however, Brown2 in 1827 and Fischer3 in 1846 being credited with having given the first descriptions. Arlt4 in 1851 also described the condition, and in 1862 Bitot5 linked hemeralopia with xerosis of the conjunctivae. Complete descriptions of the disease were first given by da Gama Lobo6 in 1864 and by von Graefe7 in 1866. The relationship of