Ординатура / Офтальмология / Английские материалы / Pediatric Opthalmology_Mukherjee_2005

B. Psychogenic

The exact cause of psychogenic tearing is not known however it is the commonest non pathological cause of tearing in children.

C. Supra Neuclear Lesion

CNS cause include supraneuclear diseases i.e. pseudo bulbar paby, tumours, encephalitis.

EPIPHORA

Epithora is defined as over flow of tears in presence of normal tear production it is a passive phenomenon. Epiphora is produced due to

A.Obstruction in tear drainage apparatus i.e. puncta, canaliculi, sac or nasolacrimal

duct or

B.failure of tear spread i.e. lid deformity like ectropion, cloboma of lower lid, tumors at the lid margin.

The tear is produced in the lacrimal gland and accessory lacrimal glands in an aqueous form to these are added mucin from the conjunctival glands and lipid from sebaceous glands of the lid. The lacrimal secretion is released in the outer corner of the superior fornix, from there it is propelled towards the puncta by capillary action, surface tension and gravity across the globe to be collected in a depression in the lower lid called lacus lacrimalis. The puncta, which are in contact with the globe imbibe the tear, that reaches the sac via canaliculi, and when the lids are closed and push the tear down the nasolacrimal duct when the lids open.20 Thus with each blink tear is constantly forced through the drainage passage about seventy five percent of drainage is through the lower punctum and rest from the upper. Epiphora becomes worse if reflex tearing is super imposed to it.

C. Causes of Epiphora

Cause of epiphora may be single or multiple extending from lid margin to nasal mucosa. For proper drainage the inner lid margin should be sharp and in contact with globe any derangement in this will cause the tear to spill over the lid margin. Lid conditions that cause epiphora are:- facial palsy, ectropion of lower lid, congenital or acquired coloboma of lower lid, growth on the lid margin and tylosis.

The puncta may be absent, atrisic or pinpoint. It may be involved in trauma. In ectropion the puncta generally looses its contact with the globe, commonest canalicular cause of epiphora is also trauma however it may be blocked following canaliculitis or dacryolith.

Most important cause of epiphora lies in the sac as chronic dacryocystitis either acquired or congenital. In both instances the sac ifself is patent, the obstruction lies in the naso lacrimal duct. However chronically inflamed sac can become fibrosed and loose its lumen. Other cause of epiphora are absence of sac following dacryocystectomy, failure of DCR or nasolacrimal and lacrimalintubation. Sometimes the opening in the inferior meatus may get blocked by a nasal growth i.e. polyp.

Tumours of the sac are unknown in children.

Trauma involving fossa for lacrimal sac or nasolacrimal duct may also cause epiphora.

A. Investigation in case of epiphora in children

1.History. Epiphora in infants and children from first month postnatal onwards is due to neonatal block of nasolacrimal duct. Watering with discharge in a new borne is most likely to be ophthalmic neonatorum rather that congenital nasolacrimal duct obstruction. In children in second decade history of chicken pox and measles may be positive. In the same age group history of bleeding from the nose is found in rhinosporidiosis of sac, history of facial injury may be associated with nasolacrimal duct obstruction secondary to fracture of lacrimal canal.

2.Examination should consist of

(a) Regurgitation test

(b) Taste test

(c) Lacrimal syringing

(d) Fluoreseine clearance test (e) Jones I and II test

(f) Examination of lid margin for ectropion, coloboma of lid margin, growth of lid margin and tylosis.

(g) Examination of nose

(h) Evidence of scar over the medial canthal ligament (i) Dacryocystography

(j) Lacrimal scintillography (k) CT Scan

(a) Regurgitation’s Test. Normally pressure over the sac does not produce regurgitation of mucoid or mucopurulent discharge from any or both the puncta, presence of regurgitation always mean obstruction in the nasolacrimal duct or failure of DCR or intubation. Generally regurgitation from lower puncta is more than from upper puncta. Regurgitation from lower puncta with out regurgitation from upper means naso lacrimal duct block with block in the upper canaliculus. Regurgitation from upper puncta only means block in lower canaliculis along with nasolacrimal duct block. Absence of regurgitation in case of chronic dacryocystitis may be due to

(i) Recent evacuated of sac,

(ii) Encysted mucocele of the sac

(iii) Pseudo sac following incomplete removal of sac. (iv) Patent DCR and intubation

(v) Fibrosed sac,

(vi) Rhinosporidiosis of sac.

(vii) In case of fistula of sac the discharge comes through the opening on the skin, so does any dye put in conjunctive comes.

(b) Encysted mucocele is a peculiar state of chronic dacryocystitis generally seen in adult women, however it may be seen in children also, where there is a distended sac, which is

visible as a diffuse oval swelling between the nose and medial canthus. The swelling is tense, non tender, non reducible without any external sign of inflammation. On exerting pressure over the sac there is no regurgitation of contents in the conjunctival sac. Generally there is no epiphora and conjunctiva is non congested, devoid of any discharge. Lacrimal syringing is not possible. No drug or dye reach the throat following instillation in the conjunctival sac.

As epiphora is invariably absent or very scanty, patient seldom complains about it. The patient generally presents with a tense painless swelling. Management is dacryocystectomy . Persistent epiphora that is a common complication of dacryocystectomy is rarely seen following dacryocystectomy in encysted mucocele as both the canaliculi are blocked. DCR or intubation is unnecessary. Purpose of removal of infected sac is to remove a potential source of infection so near the globe. An encysted mucocele may get infected and cause acute pericystitis that may ruputure forming a lacrimal fistula.

(c) Taste Test19a, 19b. As tear drains in the throat after reaching the inferior meatus, any fluid instilled in the conjunctival sac is bound to reach the throat and patient can feel the taste of fluid the instilled in the conjunctiva. It can be saline, glucose or a bitter solution. A bitter solution is a better choice. Any bitter therapeutic grade of fluid that will not irritate the conjunctiva can be used. Commonest solution used is chloramphenicol ophthalmic drops. One eye is tested at a time. A drop of chlorimphenicol is put in the conjunctival sac and patient is asked to blink a few times, a second drop is repeated after few minutes. If the lacrimal drainage is patent on the side being examined the patient will feel the bitter taste at the back of the tongue , the other side is tested after forty eight hours because if the drop is put in both the eyes and one side has a block the patient will not be able to state from which side the fluid has come. This test may be used to see the patency of DCR or intubation as well. It fails to differentiate between total and partial block. In case of partial block the drug may reach the throat after few hours or may require pressure over the sac. This test is not of much value is small children who may not complain of bitter taste.

(d) Lacrimal syringing. In this test the lower punctum is dilated with punctum dilator under local anaesthesia. A lacrimal syringe is loaded with 2cc of normal saline, lacrimal canule is attached to the syringe, the tip of the canula is attached to the syringe, and is passed through the punctum and canaliculus. The plunger of the syringe is pressed slowly.

Following observations are possible

●Fluid freely flows into the throat: (a) Naso lacrimal duct is patent. (b) DCR or intubation is patent.

●Fluid regurgitates through upper puncta and by the side of the lacrimal cancula in the lower puncta but does not reach the throat this means that there is a block in NLD but both the canaliculi and puncta are patent.

●Fluid does not regurgitate through upper puncta does not reach throat only regurgitates by the side of lacrimal canula—Naolacrimal duct and upper passage are blocked.

●Fluid flows out of hole on the skin—Lacrimal fistula with or without block in the nasolacrimal duct.

●Not possible to do syringing either from upper or lower puncta: both the puncta are blocked.

(e) Fluoreseine Clearance (Disappearance) Test. A drop of 2% fluorescein sodium is instilled in the conjuctival sac. This stains the tear. The colour of the tear becomes lighter as the tear drains. In case of normal drainage passage the fluorescine should disappear from the conjunctiral sac. The presence of fluorescence is examined on a slit lamp with cobalt blue filter. If no or little stain is present, the drainage passage is normal. If most of the stained fluid is retained after 10 minutes the drainage passage is not functioning well, may or may not have blocked nasolacrimal duct.

(f) Jones I (Primary dye test)20,21,22. This is a functional test to find lacrimal out flow under normal physiological condition. In principle it is almost same as fluoresccin disappearance test except that instead of observing disappearance of dye from the conjunctiva. It is recovered at the meatal end. A drop of fluorescein 2% is instilled in the conjunctival sac, the nasal mucous is anaesthetised and vaso constrictor drop is used to shrink the mucosa. A cotton tipped wire is passed through the external nares to reach the opening of the nasolacrimal duct under the inferior turbinate. The applicator is withdrawn after one minute and examined for presence of stain, if stain is absent the applicator is reintroduced at an interval of one minute and examined. If the nasolacrimal duct is open the dye is recovered with in five minutes. Other dyes like mercuro chrome may also be used. This test gives false result in about one third cases, mostly due to failure to place the cotton at the opening of the nasolacrimal duct. It should be remembered that the opening is situated 3 cm from the external nares. If the test is negative Jones II (Secondary ) test is done.

(g ) Jones II (Secondary dye test). In contrast to Jones I test this is not a physiological test because the dye is pushed down under pressure. A positive test denotes partial block of the nasolacrimal duct. The test is performed as in Jones I upto instillation of dye then the sac is irrigated with normal saline by a lacrimal syringe. If the stained saline is recovered from the nose the test is considered to be positive which means that the dye was held up in the sac due to partial block in the nasolacrimal duct. Care should be taken to prevent the saline going to the throat and not coming out of the nose. This can be achieved by lowering the head of the patient by 45°.

A modified secondary dye test comprises of asking the patient to blow the nose on a white tissue paper when Jones I test is negative and observe for sprinkled stain on the tissue paper.

(h) Examination of lid margin. The lid margin is examined for any evidence that cause loss of contact of lower lid margin with the globe through out its length, any loss of contact will lead to spilling of tears. Common causes are ectropion of the lower lid, coloboma of the lower lid, a small coloboma due to non repair or faulty repair of lower lid margin leads to intractable and difficult to manage epiphora, orbicularis palsy.

(i) Evidence of scar over in medial canthal ligament. Scar over the medial canthal ligament denotes previous surgery that may be simple dacryocystectomy, failed DCR or blocked intubatinon or a closed fistula.

(j) Examination of nose. As the nasolacrimal duct opens under the inferior turbinate it may be blocked by nasal polyp, nasal growth or deformity of medial turbinate.

(k) Dacroyocystography. Plain X ray without contrast fails to show any defect in the sac or naso lacrimal duct. To make them visible it is essential to use a contrast dye, then x-rays of posterio anterior and lateral views are taken. This is called simple or conventional dacryocystography. Disadvantage of this procedure is that it fails to demonstrate diverticule and filling defects. For better visualisation a modified method in which a fine catheter is introduced through one of the canaliculus and dye is injected through this. Commonly used dye is lipoidal ultra fluid. The pictures are taken when the dye is being injected. Both the sides may be catheterised simultaneously and both sides are exposed at the same time23. If the x-ray film is kept at some distance from the patient an enlarged view is obtained.

(l) Lacrimal Scintillography. Lacrimal scintillography is a reliable reproducible test for canalicular function, it is not a reliable test for naso lacrimal duct block. A positive test shows prolonged pooling of radio isotope at the obstruction site. That is instilled in the the conjunctival sac and examined by gama camera23a,23b.

(m) CT Scanning. CT scanning is ordered in case of facial trauma involving the nasolacrimal duct.

All the above investigations are always not possible in small children, lacrimal syringing should be done under general anaesthesia in children under three years as a struggling child may cause damage to the lower canaliculus that may lead to perpetual epiphora, stenosis, or may injure the cornea. In infants only test that requires to be done is examination for regurgitation.

ABNORMAL TEAR STATUS IN CHILDREN

The tear is an essential fluid to maintain the integrity of the ocular surface i.e. the portion exposed to atmosphere namely cornea and conjunctiva. Functions of the tear is to keep the ocular surface wet and glistening, it provides oxygen to the cornea. It corrects microscopic irregularities on the surface to give a better optical status to cornea, washes away debris, small foreign particles offending micro organism and chemicals, It keeps the cornea cool. The tear contains lysozyme and lactoferrin24 which are mild bacteriostatic that helps to keep infection to minimum. However these enzymes have a limit, beyond which they are ineffective specially if the organism is virulent.

The tear production is divided in to two parts :

A.A large amount called reflex tear

B.A small amount called basic or resting tear.

The tear film or precorneal tear film as its is better known has three layers with distinct origin, chemical composition and function. The most superficial is known as lipid layer followed by aqueous layer and innermost is called mucin layer.

The outer, lipid layer is secreted by the meibomian gland, glands of Zeis and Moll25.

This is an oily layer that limits evaporation and gives vertical stability to the tear meniscus by increasing surface tension so that the tear does not dribble over the lid margin. It also lubricates the surface of the globe to allow the lids to glide smoothly. The lipid layer is removed by irrigation, frequent instillation of drops or use of local anaesthesia.

Ninety Five percent of aqueous (middle) layer is secreted by main lacrimal gland and remaining by accessory glands of Krause and Wolfring. This is the thickest layer that dissolves oxygen and contains lysozyme and lacto ferrin. In fact it is the most important constituent of tear by virtues of its fluidly and amount which can be increased many folds when need arises. It acts as a flushing system that washes away debries and micro organisms. One of its main function is optical.

The main function of the innermost i.e. layer consisting mostly mucin is to anchor the aqueous layer to the ocular surface. Though the corneal surface looks smooth , in fact it has microscopic rough texture. The epithelial cells have microvilli that project forward making the surface uneven. The epithelium contains lipoprotein that make it hydrophobic i.e. , it is not wetable by aqueous layer . The inner layer is secreted by conjunctival goblet cells, glands of Manz and crypts of Henle. The mucin contain glycoprotein which are hydrophilic and turns the coreal epithelium to a wetable surface absence of mucin layer makes the cornea non wetable and dry.

The tear under normal conditions is formed at a constant rates of about 1.2 l/min26,27, total amount of tear under physiological condition is six to seven micro litre in each eye. The volume can be in increased to a certain level before it spills over the lid margin in case of reflex tearing . In case of eipphora usual amount of tear also spills over the lid margin. The tear is an optically clear fluid with refractive index of 1.357. This property is utilised in contact lens fitting. The tear contains organic and inorganic compounds in various concentration some of the values can be used to determine their concentration in serum i.e. glucose and urea sodium, potassium and chloride have higher concentration when compared with blood. pH of tear is 7.31 to 7.7. To prevent burning an eye drop should have pH that does not differ much from this. The tear is high in protein concentration. The protein fractions demonstrable in tear on electrophoresis are albumin and globulin. The gamma globulins found in normal tear are IgA. IgE which play a vital role in allergic conjunctivitis. Tear production is reduced following systemic drugs i.e. anticholinergic, antihistamines, phenothiazine, diuretics.

ABNORMALITY OF TEARS CAN BE BROUGHT UNDER THREE GROUPS

A.Excessive production with normal out flow (Reflex lacrimation).

B.Over flow of tear with normal production of tear due to block in lacrimal drainage

passage.

C.Sub normal production of tear involve and composition (Tear film abnormality, Dry eye Syndrome).

Dry eye syndrome can be brought about by.( All ages)

1.Aqueous deficiency

2.Mucin deficiency

3.Lipid abnormality

4.Irregularity of corneal or conjunctival surface

5.Abnormality of lid margin.

Aqueous deficiency tear abnormality is commonest form of dry eye syndrome followed by mucin deficiency. Lipid abnormality is very rare this is confined to absence of meibomian glands either congenital or following extensive trauma. It is seen in chronic blepharitis where a chemical change is brought about in the lipid layer that causes unstability of the tear film28,29. In chronic meibomianitis bacterial lipase hydrolyses the lipid in to fatty acid that causes disturbance in lipid layer causing dry eye.

DRY EYE SYNDROME IN CHILDREN IS BROUGHT ABOUT BY

A.Congenital absence of lacrimal gland, meibomian glands and congenital alacrima (Riley Day syndrome )

B.Traumatic—Loss of lid margin, coloboma of lid, inadvertent removal of palpebral part of lacrimal gland, acid alkali burn.

C.Exposure conjunctivitis and kertanisation of conjunctiva

D.Conjunctival scaring—

1.Late stage of trachoma (generally not encountered in first decade) extensive membranous and pseudomembranous conjunctivitis.

2.Steven’s Johnson syndrome, ocular pemphigoid, chemical burns mostly alkaline and radiaton.

E.Nutritional : Hypovitaminosis A

F.Idiopathic

G.Facial palsy

H.Neuro tropic keratitis

I.Kerato conjunctivitis sicca and Sjogren’s syndrome which are major causes of dry eye in adult are not seen in children.

Clinical Presentation of Dry Eye in Children

Symptoms of dry eye develop gradually and are varied in nature. It may be associated with systemic conditions like vitamin a deficiency, Steven’s Johnson syndrome or Riley Day syndrome. Trachoma rarely produces dry eye in children as it takes ten to twenty years to develop conjunctival scaring. Lagophthalmos is generally associated with lacrimation due to exposure keratitis and conjunctivitis. Inability to close the lid leads to poor resurfacing of the tear film. In neurotropic keratitis loss of corneal sensation results in less frequent blinking this also leads to poor tear spread.

The symptoms are unexplained redness, foreign body sensation muciod discharge with relative scanty lacrimation, blurring of vision, fluctuation of vision.

Diagnosis of dry eye

History. Detailed history of trauma, adverse drug reaction, hypovitaminosis A should be elicited

Examination

Lid for coloboma and orbicularis palsy.

Conjunctiva for evidence of vitamin A deficiency i.e. xerosis, Bitot’spot. Corena for vascularisation, opacity and filamentary keratitis,

Vital dye staining. Rose bengal and fluoresecin staining.

Rose Bengal staining. Rose Bengal is a vital stain similar to fluorescein. It has affinity for mucus and devitalised epithelium of both cornea and conjunctiva. It also stains corneal filaments and corneal plaques. Rose Bengal stains conjunctiva in the interpalpebral aperture in a triangular fashion. The triangle has its base to wards the limbus and apex away. Rose Bengal is used as 1% aqueous solution either as drop or impregnated over a strip of filter paper similar to fluorescein strip, Rose Bengal causes intense irritation when used on unanesthetised conjunctiva and hence not very popular. Xylocain 4% which is usual local anaesthetic agent used, is contra indicated prior to use of rose Bengal as it devitalises the corneal epithelium, safest local anaesthetic is proparacaine 0.5%. In contrast to rose Bengal fluorescein remains extra cellular and does not stain mucus. Alcaine blue is yet another stain that has staining property of Rose Bengal with less irritation.

Tear Film Examination30,31

Tear film examination consists of

1.Tear film stability—Tear film break up time

2.Tear quantity—Schirmer I and II

3.Tear quality

Tear film break up time

The precorneal tear film seems to be a continuos, permanent layer of tear over the ocular surface. In fact the tear film breaks down at a fixed and regular interval between the blinks and develops a so-called dry spot i.e. microscopic area devoid of tear film. This formation of dry spot is physiologically essential to start the stimulus for reflex tearing following each blink. The dry spot is repaired only to reappear. Time lapse between the last blink and appearance of a dry spot is called tear break up time or BUT. In normal eyes it ranges between 15 to 34 seconds.26 A tear film break up time less than 10 seconds is abnormal. Tear film break up time is decreased due to fault in constitution of any layer of tear i.e. mucin , lipid or hyposecretion of aqueous layer. To perform the test the patient is seated in a dimly lit room, the tear is stained with a fluorescein and the tear film over the cornea is examined by a bio microscope using a cobalt blue filter no anaesthesia is required30. The patient is asked to blink a few times and then keep the eyes open. The time between the last blink and appearance of first dry spot is tear break up time.

Schirmer’s Test 1a.

This measures total quantity of aqueous tear i.e. basic and reflex. To perform the test a specially designed filter paper of Whatman 41 grade, 5mm wide and 35 mm long is used. The paper strip is folded at one end five millimetre from the end. The patient is seated in a dimly lit room, the strip is inserted behind the lower lid on the outer side of the IPA. In such a way that the folding line rests on the inner margin of the lid and remaining 30 mm hangs out side the lid. No anesthetic is used hence irritation of the paper will initiate the reflex tearing along with basal tearing. The patient is permitted to blink but not to squeeze the lids. The tear is

drawn over the filter paper by capillary action and spreads to the other end. After five minutes the paper is removed and length of the paper wetted by tear is measured. In a normal eye this should be about 10 mm to 30 m wetting. Less than 10 mm is abnormal. If the strip is moist beyond 30 mm in lessthan five minutes it denotes either hyper secretion (lacrimation) or over flow of normal tear secretion. In both the condition dry eye status is excluded. The test should be postponed by half an hour if the lid has been manipulated.

Schirmer’s Test 1b.

Principle of the test is to eliminate reflex tearing by anaesthetising the cornea and conjunctiva. The method is same as in schirmer 1a. Only difference is that the eye is anaesthetised by 0.5% proparacaina or 4% Xylocaine. Length of the moistened strip is measured as in Schirmer Test 1a. As basal secretion is less than total secretion a reading less than 8mm is considered abnormal.

Schirmer 2 : This measures reflex tearing the procedure is same as in Schirmer 1b only difference is that the ipsilateral nasal mucosa is irritated by a dry cotton swab, the reading is noted after two minutes and a moistening of less than 15mm is considered sub normal.

In a modified schemer test a special type of thread is used instead of filter paper.

Test for tear quality. These consist of Lysozymeassay lactoferrinassay, tear osmolarity, conjunctival scrapping, conjunctival impression cytology, conjunctival biopsy. The above test are very sophisticated and require elaborate instrument and advanced expertise hence not used commonly.

Management of dry eye status in children

Fortunately kerato conjunctivitis sicca either idiopathic or secondary to Sjogren syndrome that is seen in adults are not seen in children. Dry eye status in adults is not vision threatening. However abnormal tear film status, when present in children are potentially sight threatening i.e. in Steven’s Johnson’s syndrome. Xerophtalmia secondary to vitamin A deficiency and alkaliburn.

Hypovitaminosis A is fully preventable if the child gets prophylactic does of vitamin A as prescribed for prevention of xerophthalmia under national programme and the child is immunised against measles. Steven’s Johnson’s syndrome is an unfortunate non curable disorder.

Once a dry eye status has set in the first line of treatment consists of :-

1.Replacement of tear by a tear substitute that can either be cellulose derivative or polyvinyl alcohol.

2.Mucolytic drugs to remove excess of mucin

3.Reduction of tear drainage

4.Conservation of tear already available.

The tear substitutes generally used are available as drops, ointment, gel or in the form of slow release inserts. They may have to be applied almost hourly when the child is awake. Bandage contact lenses along with tear substitutes are claimed to give more comfort to the child when it is possible to insert and retain a bandage lens.

Tarsorrhaphy in presence of orbiecularis palsy or neuro tropic kertalitis not only protects the cornea form exposure but also retains tear for a longer time.

Punctual block is indicated if the child require instillation of tear substitute more often than 5 to 6 times a day. Some times occlusion of lower punctum may suffice. It is better to give a trial occlusion by silicon plug available in two sizes. The plug is put in place by a special applicator. If the child tolerates the trial plug a permanent plug is put.

Stem Cell transplant has shown encouraging results by repopulating the corneal epithelium in Steven’s Johnson’s syndrome.

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