Vitamin A is a fat-soluble vitamin derived from provitamin carotenoids and preformed retinoids. You can obtain retinoids from your diet by eating animal foods such as dairy products, eggs, kidney and liver. You can also get vitamin A by consuming foods rich in beta-carotene such as carrots and yellow or dark vegetables.
Vitamin A helps your eyes to adapt to light changes. According to Colorado State University Extension, it also plays a vital role in tooth development, immune system regulation, gene expression, cell division, bone growth and reproduction. In addition, vitamin A keeps your lungs, throat, nose, eyes, skin and mouth moisturized. If you have sufficient amounts of vitamin A, you may reduce your chances of developing some cancers. The recommended dietary allowance is 900 micrograms daily for men and 700 micrograms per day for women.
The clinical manifestations of vitamin A deficiency occur in stages. In the early stage of deficiency, you will suffer from night blindness, and you may not be able to see properly in a dimly lit room. If the deficiency advances, you will not see anything in dim light. At this point, you should consult your physician, or else you may develop xerosis conjunctiva. Your conjunctiva, the lining under the eyelids that covers the white of the eye, will be pigmented, thickened, dry and wrinkled. At this stage, your eyeballs gain a misty appearance. Should the dryness spread further, your cornea will become hazy and lusterless. At that point, you are suffering from xerosis cornea, and you need to get medical attention or else you will develop keratomalacia, an ulceration of the cornea.
Heading Toward Blindness
Severe deficiency of vitamin A culminates in keratomalacia, a condition that affects both eyes. At this stage, your cornea becomes extremely soft, and the eyes become wrinkled and cloudy. As deficiency advances, foamy spots begin to form over the whites of your eyes. If you don't get treatment, you will suffer an infection that may rupture your cornea. As your eye tissue continues to degenerate, you will soon be blind. Keratomalacia and the lack of adequate dietary vitamin A are major causes of blinding in some developing economies. If you are living in the developed world, you can develop keratomalacia as a result of poor absorption and transportation of vitamin A due to ailments like ulcerative colitis, celiac disease, liver disease or cystic fibrosis.
The moment your physician diagnoses you with vitamin A deficiency, she will probably give you an oral dose of vitamin A. In case you are also experiencing persistent diarrhea or vomiting, an intramuscular injection can be administered as a substitute to the oral dose. You may receive an additional dose after one to four weeks.