What changes in the eye result from a deficiency of vitamin A?
(1) Night blindness: Inability of the patient to adapt to and see in darkness. In the earlier stages, it is merely increased time needed before one can see in the dark, but in the later stages night vision is seriously affected. However, not all cases of night blindness are due to vitamin A deficiency and an examination is usually needed to exclude other causes.
(2) Xerosis: A condition in which the front of the eye dries out causing, in its later stages, blindness.
(3) Keratomalacia: Only occurring in very severe cases of acute deficiency of vitamin A and malnutrition. It leads to complete loss of vision from progressive drying and death of the tissues which gradually peel or slough off leading to loss of the eye.
What changes occur in the body from a deficiency of vitamin A?
The following changes occur in the body:
(A) Dry scaly skin with thickness of the skin
(B) Mucous membranes like the inside of the lips become dry, toughened and hard
(C) Increased tendency to develop infections and cough and colds because of a decreased resistance to infection.
How is vitamin A given? What does is used for treatment and for daily maintenance?
Vitamin A can be given orally or through an intramuscular injection.
For treatment of acute deficiency start 50,000 I.U. (stands for “international units”) per day for infants and very young children and upto 200,000 I.U. per day in adults. Maintenance dose should not exceed 5,000 I.U. per day.
What are the dangers of taking excess of vitamin A, above the regular maintenance does?
Vitamin A is one of the few vitamins which, being fat-soluble, tend to concentrate in the body if taken in excess and can cause characteristic changes in the body. Infants and young children are most prone to damage from an excessive dose. However, most side effects go away on stopping the excessive doses.
(A) Effects of excess vitamin A in infants and children
Drowsiness, vomiting, and raised intra-cranial pressure (increase in pressure inside the skull).
More gradual effects are failure to gain weight, loss of hair from the head, coarse hair texture and body pain. Early fusion of joints leading to stunted growth.
(B) Effects of excess of vitamin A in adults
Headaches, blurred or double vision, body pain with new bone formation at joints, sores at the angles of the mouth and loss of hair.
(C) Effects of excess of vitamin A on the eye
Loss of eyebrows or eyelashes, paralysis of eye muscles, double vision, bulging of the eyes, squint, haemorrhage of the retina.
In view of these serious effects, excess of vitamin A is to be avoided. Though the changes described above occur due to a massive dose (75,000-150,000 units) per day, some of the multivitamin preparations available in India do have doses which may lead to similar though milder forms of reaction.
It is far safer to stick to a maximum of 2,000 I.U. in. infants and 5,000 I.U. in adults per day as maintenance dose.