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Vitamin A deficiency (VAD) or hypovitaminosis A is a lack of vitamin A in blood and tissues. [1] It is common in poorer countries, especially among children and women of reproductive age, but is rarely seen in more developed countries. [1] Vitamin A plays a major role in phototransduction, so this deficiency impairs vision, often presenting ...
A major cause of Bitot's spots is vitamin A deficiency (VAD). [4] Rarely, pellagra due to deficiency of vitamin B 3 (niacin) may also cause Bitot's spots. [5] They can also be caused by Colestyramine , which is a bile acid sequestrant which can reduce the absorption of fat soluble vitamins (Vitamins A, D, E, K)
Xerophthalmia (from Ancient Greek xērós (ξηρός) meaning "dry" and ophthalmos (οφθαλμός) meaning "eye") is a medical condition in which the eye fails to produce tears. It may be caused by vitamin A deficiency, [1] which is sometimes used to describe that condition, although there may be other causes.
UNICEF regards addressing vitamin A deficiency as critical to reducing child mortality, the fourth of the United Nations' Millennium Development Goals. [10] During diagnosis, night blindness and dry eyes are signs of vitamin A deficiency that can be recognized without requiring biochemical tests. Plasma retinol is used to confirm vitamin A status.
Keratomalacia is an eye disorder that results from vitamin A deficiency. Vitamin A is required to maintain specialized epithelia (such as in the cornea and conjunctiva ). The precise mechanism is still not known, but vitamin A is necessary for the maintenance of the specialized epithelial surfaces of the body.
Nyctalopia (/ ˌ n ɪ k t ə ˈ l oʊ p i ə /; from Ancient Greek νύκτ-(núkt-) 'night' ἀλαός (alaós) 'blind, invisible' and ὄψ (óps) 'eye'), [1] also called night-blindness, is a condition making it difficult or impossible to see in relatively low light.
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This leads to a multiple vitamin deficiency, affecting the fat-soluble vitamin A, vitamin D, vitamin E, and vitamin K. [11] However, many of the observed effects are due to vitamin E deficiency in particular. [11] Acanthocytosis in a patient with abetalipoproteinemia. Signs and symptoms vary and present differently from person to person.