Childhood blindness refers to a group of diseases and conditions occurring in childhood or early adolescence, which if left untreated, result in blindness or severe visual impairment that are likely to be untreatable later in life. The exact number of children blind in the world is not known but it is estimated that the figure is approximately 1.4 million, with up to 500,000 new cases every year. Many of these children die within months after they become blind. (International Centre for Eye Health, 2010).
The single commonest avoidable cause of blindness in children is corneal scarring, due mainly to vitamin A deficiency.
In Africa, corneal ulceration leading to corneal scaring is often associated with measles infection and in Asia severe diarrhoea may lead to acute vitamin A deficiency causing blindness. Worldwide, vitamin A deficiency is the commonest single cause of blindness in children, accounting for an estimated 350,000 new cases each year. Vitamin A deficiency is also very important as it is associated with higher infant and childhood mortality rates, particularly associated with measles. It is estimated that 60% to 80% of children who become blind from vitamin A deficiency die within a few years because of increased susceptibility to infection and sometimes lack of care (WHO 2015). Vitamin A deficiency is a public health problem in more than half of all countries, especially in Africa and South-East Asia, hitting hardest young children and pregnant women in low-income countries like Nigeria.
Xerophthalmia is a term commonly used to describe an eye showing the clinical features of vitamin A deficiency. Literally, the term means ‘dry eye’ and one sign of xerophthalmia is the dry appearance of both the conjunctiva and the cornea, described as conjunctival and corneal xerosis. Vitamin A deficiency can also cause poor night vision due to lack of visual purple (rhodopsin) in the retina.
Vitamin A deficiency can occur for three major reasons:
• Reduced intake of food rich in vitamin A
• Vitamins not absorbed from intestines usually because of diarrhoea
• Increased need for vitamin A, as occurs during infections, particularly measles.
CHILDREN AT RISK OF DEVELOPING VITAMIN A DEFICIENCY (XEROPHTHALMIA)
While vitamin A deficiency can occur at any age, the group at risk of blindness is pre-school age children, from 6 months to 6 years of age. Globally 4.4 million preschool children have xerophthalmia which is associated with increased risk of morbidity and mortality. These age and life stage groups represent periods when both nutrition stress is high and diet likely to be chronically deficient in vitamin A (West 2013). A typical child at risk of corneal blindness is a child who is 1 to 3 years old, no longer breast fed, who receives a poor diet and is malnourished, and who has developed measles (or another infection) or is suffering from diarrhoea.
SYMPTOMS AND SIGNS OF VITAMIN A DEFICIENCY AFFECTING THE EYE
It is vitally important to realize that many children who are vitamin A deficient will not have the eye signs, known as xerophthalmia (dry eye). This means that children with the eye signs are only the “tip of the iceberg”. There will be many other children in the community who are vitamin A deficient but who have completely normal eyes and vision. (Clare, G 2013). The different eyes signs of vitamin A deficiency in children as graded by the World Health Organisation 1982 is as follows:
NIGHT BLINDNESS (XN):
Vitamin A is needed to replace rhodopsin (visual purple) in the retina at the back of the eye and this is necessary for night vision. An adult or older child, on questioning, will describe the problem of night blindness but a very small child will not be able to offer this information. The mother of the child usually complains of the child not seeing well in the evening and night
CONJUNCTIVAL XEROSIS (XIA):
Vitamin A is required for the production of secretions on the surface of the eye. This dry appearance together with xerosis (dryness) of the corneal epithelium gives the condition its name, xerophthalmia. There is damage to the cells that produce secretions which moisten the surface of the eye.
BITOT’S SPOTS (XIB):
A Bitot’s spot has a typical white foamy appearance and is localised on the surface of the conjunctiva. Bitot’s spots may be found in both eyes. These may appear in children under 3 years but are more common in older children. The appearance indicates changes in the squamous epithelium of the conjunctiva with underlying xerosis.
CORNEAL XEROSIS (X2):
The surface of the cornea can have a typical dry appearance, and an ulcer.
CORNEAL ULCERATION WITH XEROSIS (X3A):
here there is an inferior corneal ulcer which can be stain green by flourescien dye.
CORNEAL ULCERATION/KERATOMALACIA (X3B):
This is the consequence of severe vitamin A deficiency. The onset is often sudden, and the cornea may melt very quickly, even over a few hours (keratomalacia). This development is most often seen in young children.
CORNEAL SCARRING (XS): The significant end stage of malnutrition causing eye damage, in a child who survives, is corneal scarring. Corneal scarring often has a marked effect on vision. The anterior part of the eye may bulge forward (anterior staphyloma) or the opposite may occur and the eye shrinks (phthisis).
It is very important to realize that children do not first develop night blindness, then Bitot’s spots and then corneal ulcers. Some eye signs reflect long standing vitamin A deficiency, whereas other eyes signs reflect severe, acute, sudden-onsent of Vitamin A deficiency. A child who is vitamin A deficient, but who does not have any of the eye signs of long standing deficiency, may develop one of the severe eye signs such as corneal ulcer as a result of infection or diarrhoea. (Clare Gilbert 2013).
TREATING A CHILD WITH SYMPTOMS OR SIGNS OF VITAMIN A DEFICIENCY
The World Health Organization recommends the following treatment schedule for children over one year old who have xerophthalmia.
• Immediately on diagnosis (Day 1): 200,000 IU vitamin A orally†
• The following day (Day 2) :200,000 IU vitamin A orally
• Four weeks later (Week 4) : 200,000 IU vitamin A orally
If there is vomiting, an intramuscular injection of 100,000 IU of water soluble vitamin A (not an oil-based preparation) may be used instead of the first oral dose.
If a child is under one year old or, at any age, weighs less than 8 kg: Use half the doses of the regimen given above.
• Immediately on diagnosis (Day 1) :100,000 IU vitamin A orally
• The following day (Day 2) :100,000 IU vitamin A orally
• Four weeks later (Week 4) :100,000 IU vitamin A orally
The third dose of vitamin A in both regimens may be given between one and 4 weeks if follow-up is likely to be uncertain. A topical antibiotic eye ointment such as tetracycline 1% or chloramphenicol 1%, 3 times a day, is recommended to reduce the possibility of secondary bacterial infection of the eyes.
PREVENTING VITAMIN A DEFICIENCY AND XEROPHTHALMIA
There are number of approaches for the prevention and control of vitamin A deficiency. These include:
A. SHORT TERM APPROACH:
It comprises periodic administration of vitamin A supplements. World health organization recommended, universal distribution schedule of vitamin A for prevention as follows:
- Infants 6-12 months old and any older children who weight is less than 8kg: 100,000 IU orally every 3-6 months.
- Children over 1 year and under 6 years of age 200, 000 IU orally every 6 month
- Lactating mothers: 20,000 IU orally once at delivery or during the next 2 months. This will raise the concentration of vitamin A in the breast milk and therefore, help to protect the breast fed infant.
- Infant less than 6 months old, not being breast fed: 50,000 IU orally should be given before they attain the age of 6 months.
- Each child with measles infection should have at least one dose of vitamin A 200,00IU orally even if his or her eyes appear healthy. If there is any evidence of eye involvement; or if the child is known to be at high risk of xerophthalmia, 3 doses should be given on day 1, day 2 and after 4 weeks.
B. MEDIUM TERM APPROACH:
it includes food fortification with vitamin A. food may be fortified with vitamin A, for example by fortifying a widely use food such as Sugar, and wheat flour.
C. LONG TERM APPROACH:
This should be the ultimate aim. It implies promotion of adequate intake of vitamin, A rich foods such as green leafy vegetables, papaya (pawpaw), spinach, mango. Education in nutrition is required to encourage breast feeding. Colostrum and breast milk contain vitamin A. Weaning foods should be rich in vitamin A, for example, mango or pawpaw. Dark green leafy vegetables may be given at one year and older. Encourage the planting of small gardens with advice as to which fruits and vegetables should be grown. Examples are mango, pawpaw, dark green leafy vegetables and carrots. Over cooking and drying fruits in the sun both reduce the vitamin A content of food and therefore should be discourage.
Vitamin a deficiency as the leading cause of preventable blindness in children can lead to increase risk of disease and death from severe infections. It is a public health problem in more than half of all countries especially in Africa and South East Asia. Crucial for third survival, supplying adequate Vitamin A in high-risk areas can significantly reduce mortality. Conversely, its absence causes a needlessly high risk of disease and death. Recognition by health workers that vitamin A deficiency is causing blindness in children should also make them aware that children in the world will be dying unnecessarily from a preventable cause. Health education for parents and communities is very important in preventing this nutritional disease.
• Aruj .K. Khurana, Comprehensive Ophthalmology, New Age international Ltd.Publishers,India 2012, Fifth Edition.
• Clare Gilbert, The eye signs of Vitamin A Deficiency, published in Community Eye Health Journal 2013: 26 (84): p66 – 67
• Prevention of Childhood blindness teaching set by international Centre for eye health 2007.
• Vitamin A Supplements: A guide to their use in the treatment and prevention of vitamin A deficiency and Xerophthalma: Second Edition, World Health Organisation Published 2007.
• West KP JR, Centre for Human nutrition Department of international Health, blooberg school of public health, Johns Hopkins University Baltimore: food Nutrition Bull 2013.
• World Health Organization programme for Preventing and Control of Vitamin A deficiency, Xerophthalma and Nutritional blindness by Demaeye EM nutritional Health 1986.
• World Health Organisation Database on Vitamin A Deficiency 1998
By Abubakar Hamadu RN, ROphN, BNSC (in view)
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