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Head lines Vitamin-A deficiency and night blindness DR. MD. RAFIQUL ISLAM, The Independent Vitamin-A deficiency along with protein energy malnutrition causes severe blinding corneal destruction. Most of the time, vitamin-A deficiency is precipitated by PEM, and other diseases which precipitate malnutrition (e.g. measles, diarrhoea). Again malnutrition is caused by vitamin A deficiency. Together, this blindness is termed as nutritional blindness, though the main factor is vitamin-A deficiency. Vitamin-A deficiency is a systemic disease that affects cells and organ throughout the body. The resultant changes in epithelial architecture are termed as "Keratinizing metaplasis". The characteristic ocular manifestation of vitamin A deficiency ranging from night blindness to corneal melting are termed as "Xenopthalmia" or Dry eye" Xeropthalmia is largely limited to the first 4-6 years of life, and is especially frequent among those 6 months to 3 years of age. Major signs and symptoms of Xeropthalmia (WHO classification) XN = Night blindness XIA = Conjuntival Xerosis. XIB = Bitot's spot X2 = Corneal xerosis X3A = Corneal ulceration/Keratomalacia X5 = Corneal scar X5 = Xeropthalmic fondues XN: Night blindness: It is usually the earliest manifestation of vitamin-A deficiency; sometimes termed as 'chicken eyes'. XIA & XIB: Conjunctival xerosis and Bitot's spot: The conjunctival epithelium in vitamin-A deficiency, is transformed from normal columnar to stratified squamous with a resultant loss of goblet cells, formation of a granular cell layer and keratinisation of the surface. Conjunctival xerosis first appears at the temporal side as an isolated oval or triangular patch, adjacent to the limbus in the inter-palpebral fissure. It is almost always present in both eyes. In some cases, Keratin and saprophytic bacilli accumulate on the xerotic surface, giving it a foamy or cheesy appearance. These lessons are known as Bitot's spots. Isolated, usually temporal, patches of conjunctival xerosis or bitot's spots are some time encountered in absence of active vitamin A deficiency. X2: Corneal xerosis: A hazy, lustreless dry appearance of the cornea, is first seen near the inferior limbus. Thick, keralinized plaques may form on the corneal surface and often more dense in the inter palpebral zone. Corneal xerosis responds within 2-5 days to vitamin -A therapy and it returns to normal appearance by 1-2 weeks. X3A & X3B: Corneal ulceration/keratomalasia. They indicate permanent destruction of a part, or all the corneal stroma, resulting in permanent structural alteration. Ulcers are classically oval or round pouched out defects. The surrounding cornea is usually xerotic. The ulcer usually starts from slightly inferior and nasal aspects. XS: Xerophalmic scar: They are usually bilateral, and indicate healed sequel of prior corneal disease related to vitamin-A deficiency. They include nebula, macula leucoma, adherent leucoma, anterior staphyloma or phthisis bulbi. XF: Xerophthalmic fundus: Small white lesions on retina, seen in some cases of vitamin-A deficiency, are only of academic interest. They may be associated with constriction of the visual fields. Treatment: Xerophthalmia is a medical emergency as it carries a high risk of corneal destruction and blindness. Effective therapy is immediate administration of massive doses of vitamin-A, with concomitant treatment of underlying systemic illness and protein energy malnutrition, and prevention of any recurrence. Treatment schedule for xerophthalmia. (A) Vitamin-A: (WHO recommendation) 1. Immediately upon diagnosis: 200,000 I.U Vitamin-A orally 2. Next day: 200,000 I.U Vitamin A orally 3. Within 1-4 weeks: 200,000 I.U vitamin-A orally. Children 6-11 months old or less than 8 kg = half the above dose; and children less than 6 months old = one quarter of the above dose. 1/m Injection of vitamin-A 100000 I.U. is usually given when the children can not swallow; in case of persistent vomiting; in severe malabsorption; or where the compliance is poor. Oral administration is preferred as it is safe, cheap and highly effective even in presence of mild diarrhoea (as it is also helpful for intestinal epithelium) (B) Medical status and diet: proper treatment includes rehydration frequent feeding with easily digestible and protein-rich food, and general supporatory care. Concurrent illness e.g. respiratory infection, diarrhoea, worm infestation, etc., should also be treated. (C) Eye care: In case of corneal involvement: (1) Broad-spectrum antibiotic ointment e.g: chloramphenicol or ciprofloxacin = 8 hourly daily. (2) Atropine ointment = 2 times daily. (D) Preventing recurrence: This is for the vulnerable children: * By inexpensive, readily available vitamin - A rich diet. * Periodic administration of large dose of vitamin-A at an interval of 4-6 months to ensure adequate vitamin-A store. Vitamin-A prophylasix Three main intervention strategies are used currently: (a) Increasing the dietary intake of foods rich in vitamin-A and provitamin-A (b) Periodic administration of large dose of vitamin-A. (c) Administration of fortified commonly consumable food items (vitamin-A fortification) (a) Increased intake of dietary sources of vitamin-A. Dark green leafy vegetables are usually the least expensive, and most widely available source of vitamin-A. It is obtained from a handful of fresh spinach (65gm) as from a small portion of liver (65gm), 4 medium sized hen's eggs, 1.7 litre of whole cow's milk, or 6 kg of mutton. The dark green leafy vegetables should be boiled, shredded (mashed or several for infants), and should be combined with a small amount of edible oil to improve vitamin-A absorption. Sources of Vitamin-A 1. Vegetables sources: Dark green leafy vegetables, spinach, carrot, tomato, pumpkin etc. 2. Animal sources: Liver, meat, cod-liver oil, shark liver oil, egg yolk etc. 3. Fortified food items: Vitamin-A rich commercially available food items. (b) Periodic administration: Oral administration of 200000 I.U. vitamin-A and half this dose for children aged 6-11 months, every 4-6 months will protect majority of the recipients. This prophylaxis may be entire neighbourhood. (e) Fortification of dietary items: Fortification, the addition of selected nutrients to common dietary items is a successful means of protecting nutritional status of children. Dalda, milk, sugar, tea, cereal grains, butter, margarine etc. may be fortified with vitamin-A. |
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