By Eyecare NGOverview | Signs | Causes | Treatment | Prevention
Vitamin A also called retinol is a fat-soluble vitamin usually stored in the liver. It is important for healthy vision, normal functioning immune system, healthy skin and fetal growth and development.
Vitamin A deficiency (VAD) is the lack or low level of Vitamin A in the body. It is the major cause of preventable blindness and severe visual impairment in children globally, particularly in developing countries of Africa and South East Asia. Manifestations of vitamin A deficiency in the eye occur in the presence of severe malnutrition, starvation and diseases like measles.
Vitamin A deficiency can lead to the death of children from illnesses like measles, respiratory infection and diarrhoea. Preschool children are at a higher risk because their diet may lack carotenoids (an important source of vitamin A obtained mostly from vegetables).
Manifestations (signs) of Vitamin A Deficiency in the Eye
The eye changes that occur from vitamin A deficiency are collectively called Xerophthalmia. It includes night blindness, conjunctival and corneal dryness (xerosis), distinct white coloured patches on the conjunctiva (bitot’s spot), corneal ulceration/keratomalacia and corneal scarring.
Night blindness (nyctalopia)
Vitamin A or retinol plays a major role in night vision. The photosensitive pigments in the rods (photoreceptors) within the retina of the eye are derived from vitamin A. The rods are responsible for night vision and require the presence of the photosensitive pigment to function well. Therefore, when there is vitamin A deficiency, the photosensitive pigments become deficient in the rods. The rods, in turn, become unable to function effectively leading to impaired vision at night or under dim lighting. People who have poor vision at night (night blindness) may have normal vision in the daytime.
This is a condition where the conjunctiva becomes dry, thick and wrinkled. Vitamin A deficiency can make the conjunctiva unable to produce mucus for the lubrication of the eyes causing poor tear quality and dryness of the surface of the eye. Under this condition, the conjunctiva also loses its lustre and smoothness and this could cause pain and poor vision in the eye. Conjunctival xerosis usually signifies mild vitamin A deficiency.
Bitot’s spots are early manifestations of vitamin A deficiency in the eye. They appear as distinct elevated white patches with foamy appearance on the conjunctiva. They are the result of an accumulation of whitish keratin debris that forms as the conjunctiva dries out. These spots usually develop in both eyes.
This is dryness of the cornea. Dryness of the cornea causes it to lose its bright lustrous appearance and become cloudy. The presence of corneal xerosis usually indicates that vitamin A deficiency is severe. Corneal xerosis progresses to keratomalacia if Vitamin A deficiency is not treated at this stage.
Keratomalacia is the thinning, softening and ulceration of the cornea. It is a severe ocular manifestation of vitamin A deficiency. When complicated with secondary bacterial infection, the cornea may perforate, leading to blindness.
When corneal ulcers heal, they leave white scars. White scars on the cornea can cause blindness if the scars occur in the two eyes bilateral and cover the central part of the cornea.
Note: Severe xerophthalmia is not an isolated eye disease or condition but is a result of generalised malnutrition and starvation. Children with severe xerophthalmia are likely to suffer from systemic illnesses such as diarrhoea, respiratory illness and measles.
Apart from the eye manifestations, vitamin A deficiency also manifests in other parts of the body. Some of the signs in the other parts of the body include dry, thickened and scaly skin, dry lips, thickened tongues, retarded growth and impaired immunity leading to increased vulnerability to infections.
Causes of Vitamin A Deficiency
- Malnutrition: Children whose diet is of poor quality are at a higher risk of being vitamin A deficient.
- Lack of breastfeeding: Breast milk is a rich source of vitamin A for newborn babies. Children who are not breastfed or weaned too early are at risk of Vitamin A deficiency.
- Lack or low level or vitamin A in breast milk: If a breastfeeding mother is Vitamin A deficient, the baby is likely to become vitamin A deficient especially if he/she is exclusively breastfed.
- Conditions and diseases that interfere with the metabolism of Vitamin A in the body. The presence of conditions and diseases that interfere with the metabolism of Vitamin A can lead the Vitamin A deficiency. These diseases could either prevent the storage of vitamin or limit its absorption from the blood or cause excessive excretion of the vitamin through the urine. Some of these diseases include liver disease, cancer, coeliac disease and disease of the pancreas.
Treatment for the Eye Manifestations of Vitamin A Deficiency
Treatment for the eye manifestations of vitamin A deficiency in children has two parts.
- Correction of vitamin A deficiency: This is the first intervention in the treatment of eye manifestations of vitamin A deficiency and is done by giving children multiple doses of vitamin A in the form of tablets or injections.
- Treatment for the eye manifestations: In addition to providing vitamin A, other treatments are required to take care of the conditions in the eye. If the cornea is ulcerated, antibiotics are given to prevent or treat secondary bacterial infection. Surgery may be done to improve vision or aesthetics of the eye.
Vitamin A deficiency in children can be prevented in the following ways:
- Routine administration of vitamin A in infants and young children
- Eating a healthy and balanced diet rich in vitamin A. Some food sources of vitamin A include carrots, spinach, Kale, sweet potatoes, peaches, liver, egg yolks, fish liver oils and Vitamin A fortified cereals
- Breastfeeding babies.