<prompt> Vitamin A deficiency is considered a public health problem if prevalence rate of night blindness in children between 6 months to 6 years is more than -0.010.050.11.00  <response>: - night blindness or inability to see in dim light is a manifestation of vitamin A deficiency. - Vitamin A deficiency is considered a public health problem if prevalence rate of night blindness in children between 6 months to 6 years is more than 1 percent. Reference : Parks textbook of preventive and social medicine, 23rd edition, pg no:616 p 