Influence of protein deficiency and sex on the development of ocular lesions and survival time of the vitamin A deficient rat.

ATTENTION has recently been drawn to the frequent association of eye signs attributable to deficiency of vitamin A with systemic manifestations of protein malnutrition in children (McLaren, 1958). Whilst a deficiency of the vitamin in the diet would seem to be an adequate explanation, it is possible that the eye changes may result from an adverse effect of protein lack on one or more of the stages of vitamin A metabolism in the body. This association is especially common in Indonesia, where de Haas, Posthuma, and Meulemans (1940) described 75 per cent. of their cases of xerophthalmia as having "general dystrophy"; Oomen (1953) and the writer (unpublished observations) found a similar percentage of kwashiorkor cases there with xerophthalmia and keratomalacia. From the same country has come a recent report (Yap-Kie-Tiong, 1956) suggesting that protein deficiency is responsible for the most severe degree of eye lesions classed as keratomalacia. This is based on a study of plasma protein and vitamin A determinations of ten children with xerophthalmia and ten with keratomalacia. Much turns upon the definition of the terms used and a division of cases into two such groups is arbitrary as the two conditions merge imperceptibly the one into the other. Furthermore, correlation between the estimations made and nutritional status is doubtful and control subjects were not used. It is possible to interpret the difference between the mean total protein values for the two groups as being an indication that the group with keratomalacia was eating a diet lower in protein than the other group. If so, then it might be reasonably argued that they might also be consuming less carotene and vitamin A, thus accounting for the more advanced eye changes. That the patients with keratomalacia were much more seriously ill than the others is evident from the fact that they rarely survived more than a day or two after admission to hospital (Yap-Kie-Tiong, personal communication).