Vitamin A deficiency exists when the chronic failure to eat sufficient amounts of vitamin A or beta-carotene results inlevels of blood-serum vitamin A that are below a defined range. Beta-carotene is a form of pre-vitamin A, which is readilyconverted to vitamin A in the body. Night blindness is the first symptom of vitamin A deficiency. Prolonged and severevitamin A deficiency can produce total and irreversible blindness.
