title: History of nightblindness: a simple tool for xerophthalmia screening.
abstract: Among 5925 preschool-age children examined in a house to house rural field study, X1B (Bitot's spot with xerosis) and/or an history of nightblindness (XN) was presented in 325. Mean serum vitamin A levels among those with isolated XN (13.9 microgram/dl), isolated X1B (13.4 micrograms/dl), and coexistent XN/X1B (12.1 microgram/dl) were similar, and significantly below that of normal age/sex/neighborhood matched controls (17.6, 17.1, and 18.3 microgram/dl, respectively). The mean serum vitamin A level of the matched controls was significantly below that of normal, randomly sampled children from the study population as a whole (20.6 microgarm/dl). As independent screening criteria, disregarding the presence of absence of other signs, twice as many children had a history of XN as had X1B (84 and 41% of all clinically abnormal children, respectively). Of randomly sampled children 55% but only 15% of cases of XN had serum vitamin A levels above 20 microgram/dl. Of children with a history of nightblindness 97% had impaired scotopic vision on objective testing, but the mean serum vitamin A levels among test positives and negatives were identical. These results suggest a properly eleicited history of nightblindness can be almost as specific and far more sensitive an index of vitamin A deficiency and early xerophthalmia than the prescence of Bitot's spots (X1B), and that vitamin A deficiency is a clustered, neighborhood phenomenon rather than an isolated, sporadic occurrence.
mesh_terms: D002648:Child; D002675:Child, Preschool; D003318:Corneal Opacity / Q000150:complications / Q000453:epidemiology; D005260:Female; D006801:Humans; D007214:Indonesia; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008403:Mass Screening; D009755:Night Blindness / Q000150:complications / Q000453:epidemiology*; D012424:Rural Population; D013577:Syndrome; D014801:Vitamin A / Q000097:blood; D014802:Vitamin A Deficiency / Q000150:complications / Q000453:epidemiology; D014985:Xerophthalmia / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology*
chemical_list: D014801:Vitamin A