A prevalence study of vitamin A deficiency and xerophthalmia in northeastern Thailand.

An epidemiologic survey of the prevalence of xerophthalmia and vitamin A deficiency was conducted in May and June 1985 in a multistage random sample of 1,772 children 1-8 years of age from 16 rural villages and the capital city of the Sakon Nakhon province in northeastern Thailand. Data of clinical eye examinations were available for 92% (n = 903) of the eligible children aged 1-5 years (n = 982); history of night blindness was obtained from a reliable source from 93% (n = 1,644) of the whole sample; and biochemical data were available for 60% (1,060) of the children examined. The distribution of clinical signs of xerophthalmia and serum retinol levels differed between the rural and urban areas. In the urban area, no signs of xerophthalmia or deficient serum retinol levels were found in the preschool children examined. The prevalence of night blindness in the rural area was 1.3% in children aged 1-5 years (95% confidence interval (Cl) 0.7-1.9); Bitot's spots were seen in 0.4% (95% Cl 0.1-1.0); 12.7% (95% Cl 9.9-15.5) showed deficient serum retinol levels (less than 0.35 mumol/liter). Of the children aged 1-8 years, 9.6% (95% Cl 7.8-11.4) showed deficient serum retinol levels. In the rural area, the prevalence of night blindness, Bitot's spots, and deficient serum retinol levels indicates a problem of public health importance according to World Health Organization criteria.