This journal issue focuses on problems caused by vitamin A deficiency and its effects on vision. Although these conditions are quite serious and widespread in some areas of the world, they can easily be treated by inexpensive means. The report begins with a discussion of xerophthalmia, the most frequent cause of blindness in preschool-age children in most developing countries. Subsequent sections of the report explore (1) the history of vitamin A deficiency among human beings; (2) terminology and units of measurement; (3) metabolism; (4) vitamin A requirements and recommended intakes; (5) dietary sources of vitamin A; (6) the epidemiology of vitamin A deficiency and xerophthalmia; (7) clinical signs of vitamin A deficiency; (8) indicators of nutritional status with respect to vitamin A; (9) criteria for determining the extent of xerophthalmia and of vitamin A deficiency, from a public health standpoint; (10) the geographic distribution and prevalence of xerophthalmia; (11) treatment; and (12) prevention. Appended material describes the anatomy of the human eye. (RH)