title: Pupillary threshold as an index of population vitamin A status among children in India.
abstract: Two hundred seven vitamin A-deficient southern Indian children aged 1-7 y (mean age: 56.9 mo) underwent testing of dark-adapted visual and pupillary thresholds in their village setting according to a previously reported protocol. One hundred thirty (62.8%) of the children also underwent serum retinol testing, and 178 (86.0%) participated in a randomized, placebo-controlled vitamin A dosing trial with pre- and postdose testing of dark-adaptation threshold. Most subjects (184 of 207, 88.9%) were able to complete pupillary testing, an objective sign requiring minimal cooperation, including a high proportion of the youngest children (72.2% of subjects aged 2 y). The proportion of children completing visual threshold testing, which requires greater understanding and cooperation, was significantly smaller than that able to complete pupillary testing (131 of 207, 63.3%; P < 0.0001, chi square). At baseline (predosing), the mean serum retinol concentration declined in linear fashion with a higher pupillary threshold (0.73 mumol/L with a score < or = 4; 0.47 mumol/L with a score > or = 8; P < 0.01). The mean pupillary threshold for these highly vitamin A-deficient Indian children (-0.622 log cd/m2) was significantly higher than that for 136 more moderately deficient Indonesian children (-0.985 log cd/m2; P < 0.001, two-sample t test) and 56 normal American children (-1.335 log cd/m2; P < 0.0001, two-sample t test). The improvement in pupillary dark-adaptation testing was not significant for children receiving vitamin A or placebo, though there was a nonsignificant trend toward greater improvement in children receiving vitamin A (P = 0.2, two-sample t test). Pupillary threshold testing represents a new, noninvasive, practical, and seemingly valid approach to assessing the vitamin A status of a moderately to severely deficient preschool population.
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, USA.
authors.forename: A M
authors.initials: AM
authors.lastname: Sanchez
authors.forename: N G
authors.initials: NG
authors.lastname: Congdon
authors.forename: A
authors.initials: A
authors.lastname: Sommer
authors.forename: L
authors.initials: L
authors.lastname: Rahmathullah
authors.forename: P G
authors.initials: PG
authors.lastname: Venkataswamy
authors.forename: P S
authors.initials: PS
authors.lastname: Chandravathi
authors.forename: L
authors.initials: L
authors.lastname: Clement
mesh_terms: D000375:Aging / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D003623:Dark Adaptation / Q000502:physiology; D004311:Double-Blind Method; D005260:Female; D005527:Food, Fortified; D006801:Humans; D007194:India / Q000453:epidemiology / Q000208:ethnology; D007223:Infant; D008027:Light; D008297:Male; D008452:Maximum Allowable Concentration; D009752:Nutritional Status; D011680:Pupil / Q000502:physiology*; D014801:Vitamin A / Q000097:blood* / Q000494:pharmacology; D014802:Vitamin A Deficiency / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology
chemical_list: D014801:Vitamin A