Ординатура / Офтальмология / Английские материалы / Pediatric Opthalmology_Mukherjee_2005
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PEDIATRIC OPHTHALMOLOGY |
Primary signs96 |
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X |
1A |
Conjunctival xerosis |
X |
1B |
Bitots spot with conjunctival xerosis |
X |
2 |
Corneal xerosis |
X3A Corneal ulcer with xerosis
3B Keratomalacia
Secondary signs
XN |
Night blindness |
XF |
Xerophthalmic fundus |
XS |
Xerophthalmia scar |
Where X stands for xerosis
Symptoms of xerophthalmia can be related to
1.Conjunctival and corneal
2.Night blindness.
One may precede the other or may be found together. There are instances where the eye may advance into conjunctival and corneal xerosis without night blindness, vice versa is rare.
Clinical signs
1.Conjunctival—Vertical folds on looking laterally
2.Dryness of conjunctiva
3.Pigmentation on dry conjunctiva
4.Bitot’s spot.
Bitot’s spot94. These are triangular raised white areas developing mostly on the lateral side of bulbar conjunctiva in the inter palpebral aperture little away from the limbus. The triangle has its base towards the cornea and apex towards outer canthus. The surface of the triangle is foamy, the foamy substance can be removed with ease only to reappear. The foam is caused by action of xerosis bacilli. The surface of Bitot’s spot does not wet with tear. Kajal and Surma applied to lid margin do not stain normal conjunctiva but the surface of the Bitot’s spot and dry conjunctiva stains with Kajal and Surma. Bitot’s spot is not specific of vitamin A deficiency. It can be idiopathic as well. Bitot’s spot due to vitamin A deficiency disappears after sometimes but idiopathic Bitot’s spot does not respond to administration of vitamin A and is seen in older children and adults.
2. Corneal signs. Cornea develops dry spots, tear film break up time is less than 10 seconds. Tear production and composition of tear is within normal limits, abnormal tear break up is due to changes in corneal epithelium. The cornea is lusturless. These early changes are reversible and respond promptly to systemic administration of vitamin A. If the condition is not arrested at this stage it proceeds to corneal ulceration which is generally central, surrounded by hazy or opaque cornea. Peculiarity of these ulcers is that they are aseptic in nature. There is minimal congestion and hardly any pain. The stroma is involved following break in epithelium. The stroma is involved more easily and severely in vitamin A deficiency
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than seen in normal eye when epithelium is damaged. At this stage vigorous local and systemic treatment may avert perforation but complete recovery with clear cornea is never achieved.
Keratomalacia. This is advanced stage of xerophthalmia. Here the cornea becomes soft and virtually melts away within twenty to twenty four hours. This has not been produced in experimental animals. The central part is covered by a white gelatinous material due to collagenase enzyme. Perforation with protrusion of intraocular tissue is inevitable. Scar following keratomalacia is generally bilateral, one eye may be more advanced than the other. In developing countries with eradication of small pox, keratomalacia has become foremost cause of bilateral corneal staphyloma in children.
Night blindness. Night blindness due to vitamin A deficiency is of acute onset. The child prefers to sit in one place and avoid moving. The child is so incapacitated that he may not locate his food in the plate placed in front of him. This has been termed as chicken blindness. Night blindness due to vitamin A deficiency responds to systemic vitamin A therapy quickly.
Xerophthalmia due to vitamin A deficiency is never isolated. It is invariably associated with protein caloric malnutrition. It is very common following attack of measles, diarrhoea, malaria, worm infection, mal-absorption syndrome.
Management of xerophthalmia97, 98
Management consists of :
1.Prophtlaxis
2.Therapeutics
Prophylaxis98. Xerophthalmia is one of leading cause of bilateral blindness in children which is fully preventable by simple and cost effective methods. Moreover vitamin A deficiency is also responsible for a large number of deaths in infants.
Prophylaxis in mother and new born. Vitamin A is stored in liver and secreted in mother’s milk in sufficient quantity to prevent deficiency in infants. Hence it is of utmost importance that mother has good storage of vitamin A during pregnancy and lactation. The colostrum is rich in vitamin A, hence soon after birth the child should be put to breast of the mother and allowed to take the collustrum. If the child gets sufficient amount of mothers milk and thrives on it, there is no need of any supplementation of vitamin A. The child should be breast fed as long as there is sufficient mother’s milk for the child. If top feed is to be started bovine milk is preferred over formula milk. From the age of five months solid food should be started in consultation with pediatrician, adding green leafy vegetables, yellow fruits and vegetables to cereals and pulses.
Vitamin A prophtlaxis between 6 months to 6 years.Every child between six months to six years should get an oral dose of 200,000 unit of vitamin A concentrate. Under National Programme of Prevention of Xerophthalmia, vitamin A is distributed free from primary health centres, government hospitals. The first dose may be delayed up to nine months and given along with measles vaccine. It is not clear if vitamin A deficiency precipitates attack of measles or vice a versa. However administration of vitamin A along with management of measles has reduced mortality in measles.
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Fortification of food with naturally occurring vitamin A. Children and young adults should be encouraged to take vitamin rich food as part of daily diet in the form of green vegetables, yellow tubers, yellow fruits.
Daily requirement of vitamin in normal individual :
1.Pregnancy and lactation—3000-3500 IU (300 mg to 750 mg)
2.0-4 years—1000 to 1200 IU
3.School children—2250 IU
Management of clinical xerophthalmia :
Night blindness99. Intra muscular injection of water soluble 100,000 IU of vitamin A followed by (1) 200,000 IU oral after seven days or (2) Repeat 100,000 IU intra muscular after seven days.
Xerosis—200,000 IU of oral vitamin.
Keratomalacia
WHO recommendation :
1.Immediate upon diagnosis - 200,000 IU orally.
2.Next day—200,000 IU orally
3.After seven days—200,000 IU orally.
4.Repeat 200,000 IU every six months up to six years of age to prevent recurrence.
5.If the child is unable to take oral feed or has vomiting, 100,000 IU of water soluble vitamin A is given as injection.
Children less than 8 kg should receive half the above dose and under 4 kg quarter of the above dose.
Ocular therapy
A.Local instillation of antibiotic drops every 2 hourly and ointment during sleep to prevent sticking of lids.
B.Atropine—In all cases of corneal involvement irrespective of actual ulceration atropine is used as 1% ointment two times a day. Atropine as drop is better avoided in children for one drop of atropine contains more than therapeutic dose of atropine. Thus one drop in each eye reaches almost lower level of toxicity especially when the child is under weight.
C.Local retinol—Tretinoin 0.1% as drops in oil three times a day is claimed to retard progress of corneal involvement.
D.Local tear substitutes—Though aqueous part of tear film is not reduced yet it fails to wet the cornea and conjunctiva due to changes in epithelium. Local artificial tear may help in preventing the cornea from drying.
The child’s total protein and calories should be calculated and supplied because vitamin A deficiency does not occur in isolation. There should be adequate supply of other vitamins and minerals specially the trace elements.
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Other causes of xerosis. Coloboma of lids, ectropion of lid, lagophthalmos, proptosis, Steven-Johnson’s syndrome, Riley Day syndrome, acid alkali burn.
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CHAPTER 8
Disorders of the Uvea in Children
Uvea is the middle vascular pigmented coat of the eye ball. It is divided into three parts.1 1. Iris 2. Ciliary body 3. Choroid. All the three parts develop from neuro ectoderm and mesoderm.
The iris
Iris is the most anterior part of the uvea that is visible on oblique illumination. It is practically a diaphragm of blood vessels and unstripped muscle fibres, held together by loose stroma. It is coronal to the cornea but not parallel to it. It is 12 mm. in diameter, from root to root, all round with a circular hole in the center the pupil. Thickness of the iris is not uniform. It is thinnest at its insertion (root) to the middle of the anterior border of the ciliary body. It’s thickness is maximum at the collarette, then its thickness gradually diminishes towards the pupil in a rounded fashion. The iris divides the aqueous chamber into anterior and posterior chambers. The colour of the iris not only varies from race to race, but also from person to person. It may vary in two eyes or in the same eye. Colour of the iris is due to the presence of pigments in the iris. More the pigment, darker is the iris.
Colour of the iris of the new born is lighter than that of adults. Some of the stromal vessels are visible in the iris of the new born, which disappear after a few weeks.
Difference in the colour of the iris in two eyes is called heterochromia. Difference in colour of one iris from its counterpart is called heterochromia iridum while difference in colour of iris in the same eye is called heterochromia iridis.2
Heterochromia is generally congenital in nature. In albinism the iris is generally bluish, almost translucent that transilluminates with reflected light.
The anterior surface of the iris is rough. It is divided into two zones by a circular raised irregular lines called the collarette i.e.
1.Pupillary zone that is 1.5 mm. wide from the collarette to pupillary margin, is lined by a thin zone of pigment called iris ruff, which is in fact continuation of the posterior pigment layer. The pupillary zone contains the sphincter pupillae muscle that is a smooth muscle and originates from the neuroectoderm and is supplied by parasympathetic nerve.
2.The ciliary zone is a wider zone that extends from collarette to the root of the iris. It is relatively rough due to the presence of series of radial elevated ridges that
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