Studies on vitamin 'A' deficiency.

THE role of Vitamin A in the metabolism of
visual purple has been reported by several
workers (4, 10, 8, 7). Vitamin A was shown
to be a precursor of the visual purple in the
pigments of frog's eyes (9). The visual purple
system uses up vitamin A and is, therefore,
dependent on the diet for its replacement (9).
The deficiency of Vitamin A will, therefore,
cause difficulty or inability to see in dim light.
The deficiency of Vitamin A in the human
,ystem is associated with a number of eye
lesions. In adults and grown-up children
night-blindness is the first common symptom of
Vitamin A deficiency. The second stage of the
disease results in the dryness of the conjuctiva
(xerosis). Keratomalacia is an advanced stage in
the eye manifestations of adults as well as infants.
This starts with the softening of the cornea and
ultimately leads to the destruction of the eye
and blindness through secondary infections.
The prevalence of such eye diseases is very
common among people who suffer from malnutrition.
Among Japanese children Mori (6)
found the incidence of xerophthalmia to be
very high, especially in times of famine.
Block (2) reported the occurrence of the same
disease among the poor Danish and attributed
it to the general use of skim milk in infant and
hild feeding. Similar cases have been reported
in Roumania and Vienna (3). In India, a
survey of Vitamin A deficiency was carried out
at Calcutta (1). A similar survey was made by
the author in Lahore (Punjab) in 1945 and this
paper presents the results of the same.