in partial fulfil]ment of the - MSpace - University of Manitoba

(1977 ). nner using poker chips, except that the light adaptation period
was 2 minutes and that subjects were light adapted by starring at a
lighted x-ray view box at a distance of 45 cm. in the Baltimore series,
the procedure was identical to the one used in adults by Vinton and
Russell ( 1 981 ) . Red and blue Munsell color discs were used.
IlluminaLion was set to emit at the work surface 0.0068 candela/n2.
Pretest retinal bJ.eaching rlas accomplished by having the test subject
stare at a lighted portable x-ray view box at a distance of 0.05 cm for
one minute.
In Baltimore, a food frequency history based on customary intake of
Vitamin À rich foods and Vitamin supplemenls was taken from parents.
The Vitamin A and provitamin contents of the diets were estimated using
tables of food conposition. in Guaternala, a 4 ml sample of whole bl-ood
was taken. Vitamin À levels and plasma zinc concentration were determined.
However, a blood test, involving determination of blood vitamin
À level, v¡as not done in Baltimore.
The 5-12 year o]d children in Guatemala were able to understand the
instructions, manipulate the discs and cooperate throughout the testing
procedure. 0f the'18 ,4-5 year old children enrolled in Baltinore, 16
ß9%) successfully compleLed the test. One subject in Baltimore (a boy
aged 5) played with the chips but did not understand the mission of the
test; another, (a girr aged 4), asked to be excused to relurn to the
playroom.
For the Guatemalan group, the mean time taken Lo complete the lest
was 144 seconds, and for the Baltimore group, the mean time was 171
72