Impact of massive doses of vitamin A on incidence of nutritional blindness.

In a longitudinal study designed to assess the impact of a massive-dose vitamin A programme on the incidence of keratomalacia, 50 000 preschool children in 450 slum areas in Hyderabad city (India) were given 200 000 IU of vitamin A once every 6 months. During the study period, the incidence of keratomalacia in areas covered by the programme decreased by about 80%, while in control areas the reduction was of the order of 20%. To test whether large doses of vitamin A supplements prevented keratomalacia, a case-control analysis was done, with patients with severe protein-energy malnutrition being used as controls. The high odds ratio clearly indicated that keratomalacia was more likely to occur in children not receiving supplements.