Vitamin A deficiency and child blindness in the developing world.

Vitamin A deficiency is present worldwide in the developing countries. Bangladesh, India, Indonesia and the Philippines appear to be the most afflicted but many countries in Africa and some in Central and South America have the same problem. The most tragic manifestation of the deficiency is blindness in young children; xerophthalmia, leading to keratomalacia with melting or dense scarring of the cornea. The World Health Organization (WHO) considers xerophthalmia to be one of the four largest preventable causes of blindness in the world, the others being trachoma, cataract and onchocerciasis. The magnitude of the problem of vitamin A deficiency and the possibility of action to control it has only been fully realized in the past 12 years or so, although Oomen et al. (1964) described its worldwide prevalence. Even now the eye signs may not be generally recognized. This is particularly so in Africa. Recently the WHO (1982) together with the US Agency for International Development have made preliminary surveys in parts of many African countries. They found vitamin A deficiency eye signs in certain districts of Benin, Malawi, Zambia and Upper Volta; signs were already recognized in Northern Nigeria (Whittle et al. 1979). On present evidence it does not appear to be a public health problem in Kenya or in those parts surveyed of Mali, Somalia, Sudan, Cameroon or Ethiopia; although night blindness may be endemic in certain seasons in these countries. Further assessment is necessary (WHO, 1982). The most vulnerable group are children from birth to 5 or 6 years of age, with the peak coming between 2 and 3 years of age. They are nearly always severely malnourished, many weighing less than 60% of their expected weight-for-age. Often they have, or are recovering from diarrhoea, from upper respiratory infections or from measles, which is particularly severe in Africa. They come from the poorer sections of the community but, although poverty is the overwhelming factor, ignorance of the foods needed by growing children also contributes to the underand malnutrition. During the past decade, led by the WHO and non-governmental agencies, such as the Royal Commonwealth Society for the Blind, UK, and Helen Keller International, USA, there has been a resurgence of interest in xerophthalmia or, as it can reasonably be called, blinding malnutrition. The most precise and farreaching results have come from work in Indonesia, carried out by the Indonesian Government in conjunction with Helen Keller International and US AID (Sommer, 1982). The chief members of the team were Dr A. Sommer, an ophthalmologist also trained in epidemiology and now head of the newly set-up International Centre for Epidemiologic and Preventive Ophthalmology at the Johns Hopkins