What Are Vitamin A deficiency Disorders?

Deficiency disorders of vitamin A mainly involve the eye. Deficiency of vitamin A has become less common, even in developing countries due to use of large prophylactic doses (110,000 micrograms orally to children of 1 to 6 years of age, every 6 months) of vitamin A to infants and availability of vitamin A fortified foods. The vitamin A deficiency disorders include night blindness, conjunctival xerosis, corneal xerosis, Bitot’s spots and keratomalacia. There are also extra ocular manifestations. Xerophthalmia or dry eye is the term, which comprises all the ocular manifestations of the vitamin A deficiency including night blindness to keratomalacia.

Night blindness:

The vitamin A deficiency first causes night blindness or inability to see in dim light. This is common in poor under developed countries and seen mainly in children. The mother first detects the condition when she observes that the child can not see in dark or in the evening. This is due to impairment in dark adaptation, which requires vitamin A. Night blindness increases unless the vitamin A consumption is increased and gets worsened if the child has diarrhea or other infection.

Conjunctival Xerosis:

This is the first clinical sign of vitamin A deficiency where the conjunctiva becomes dry and non wetable. The conjunctiva appears muddy and wrinkled instead of shiny and smooth. This is described as “emerging like sand bank at receding tide”.

Bitot’s spot:

These are ‘triangular, pearly white or yellowish, foamy” spots on the either side of cornea. In children Bitot’s spots indicate vitamin A deficiency, but in adults the presence of Bitot’s spots indicates the sequel of earlier deficiency in childhood. Bitot’s spots are frequently bilateral (present on both eyes).

Corneal Xerosis:

This is the stage of serious vitamin deficiency and can lead to corneal opacity and blindness. At first the cornea appears dull and dry (non wettable) and if not treated promptly can lead to corneal opacity. If deficiency is severe there may be corneal ulceration and if the cornea heals also there may be scar and opacity which affect vision.


This is the most serious form of vitamin A deficiency and there is liquefaction of cornea. It is a grave medical emergency. The whole cornea or part of it may become soft and burst open, which can happen very rapidly. If the eye collapses the vision is lost permanently. In poor and under developed countries keratomalacia is one of the commonest causes of blindness.

Extra ocular manifestations of vitamin A deficiency include anorexia, growth retardation, follicular hyper keratosis etc. But they are non specific. New studies suggest there is significant increase in morbidity and mortality even if there is mild vitamin A deficiency.

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