Ординатура / Офтальмология / Английские материалы / Pediatric Opthalmology_Mukherjee_2005

present and is a dominant feature cycloplegic drugs are used in acute phase, atropine sulphate is used as one percent drop two times a day under supervision along with local steroids. Once acute phase has subsided atropine can be replaced by any of the following short action cycloplegic i.e. 2% home atropine hydrobromide, 1% cyclopentolate hydrochloride or 1% tropicamide. Only sympathomimetic drug like phenyl pherine has no role in management of uveitis. It only produces immediate blanching of conjunctival vessels giving a false impression of white eye. Children on prolonged local steroids should be closely monitored for rise of tension, steroid induced cataract and secondary infection.

Acanthamoebae keratitis38, 75, 76

Acanthamoebae keratitis was unknown three decades earlier because the organism, which is found normally in human throat and pharynx was thought to be non-infective as far as eyes were concerned. However, it remains a relatively rare disease, incidence of which is increasing. There are eight species of acanthamoebae that cause corneal ulcer. The organism is found in two forms i.e. trophozoite and cyst. Besides throat and pharynx the organism is commonly found in fresh water, soil, home made contact lens solutions, all types of contact lenses.

Keratitis produced by acanthamoebae is indolent, non-suppurative, resistant to antibiotic, antiviral and antifungal drugs. It is difficult to culture. It thrives on gram negative bacteria and cynobacteria at 25°–35°C temperature.

Predisposing factors include :

1.Use of any type of contact lens

2.Use of non standard contact lens solutions specially home made.

3.Swimming in a contaminated pool.

4.Trauma by vegetable matter. It is being reported more commonly among non contact lens users following trauma.

Corneal lesions may be as mild as epidemic kerato conjunctivitis or as severe as Descemtocele or perforation. The condition can be put in following three stages :

Stage I. This initial stage mimic herpes simplex or bacterial keratitis and is confused as such. The changes consist of one or combination of many punctate lesions, pseudo dendrite and epithelial defect. Symptoms at this stage are foreign body sensation, redness and photophobia.

Stage II. This consists of anterior stromal ring, disciform keratitis, formation of double ring, limbitis and scleritis.

Stage III. Corneal abscess, severe disciform keratitis, Desmetocele, iritis, scleritis, hypopyon and sometimes hyphaema.

All the stages are very painful. Pain is out of proportionate to the size of corneal involve-

ment.

Diagnosis77, 78, 79. Diagnosis is generally missed. A high index of suspicion in all painful ulcers developing in contact lens users or following trauma that do not respond to usual corneal ulcer treatment generally leads to correct diagnosis. However diagnosis after four weeks of onset is always fraught with failure.

All suspicious cases of kerato acanthamebae should undergo examination of corneal scrapping to exclude bacterial, viral and fungal ulcer. Unfortunately herpes simplex keratitis is very common with acanthameba keratitis. The scrapped material should be stained with hematoxylin and eosin, Gram’s stain, Giemsa stain, lactophenol cotton blue and celluflour white. The material can be examined after immuno fluorescent stain.

Cysts have a typical polygonal double walled appearance. It is difficult to culture the organism, however, the material may be inoculated on blood agar, non nutrient agar79a or chocolate agar that has been overlaid with killed E.Coli.

Management. Treatment of kerato acanthameba is difficult. It requires constant and prolonged treatment with specific drug, result of which may be frustrating.

Management consists of76 :

1.Prevention by proper contact lens storage and cleaning.

2.Instillation of anti acanthamebial drugs.

3.Usual treatment of corneal ulcer, uveitis and secondary glaucoma.

4.Penetrating keratoplasty.

Anti acanthamebic drugs are :

1.Biguanides—Polymeric-polyhexa methylene biguanide 0.02% solution hourly for first three days then alternate hourly for 2 to 3 weeks. The frequency is reduced over months.

2.Diamidine

1.Propamindine 0.1%

2.Hexamidine 0.1% as solution to be instilled for 2 days, followed by six times a day for 3 months.

3.Antibiotics—Neomycin 5.0 mg/drops to be instilled 2 hourly.

4.Antifungal

A. Local

(i) Ketaconazole

(ii) Clotrimazole 1% drop B. Systemic

(i) Ketaconazole

(ii) Fluconazole

Usual treatment of non healing corneal ulcers consists of :

(i) Strong cycloplegic i.e. atropine sulphate 1% drop two times a day (in children atropine should be used under supervision).

(ii) Repeated debridement

(iii) Local beta blockers to keep the tension low.

Role of local steroids is controversial and better avoided.

Penetrating keratoplasty seems to be the ultimate method to salvage vision and save the eyeball. The infected corneal button removed from the patient should be subjected to histopathological identification of the organism.

All persons using contact lens should be warned about possibility of contamination by various organism. They should be instructed to use standard cleaning solution. Use of home made solution should be a taboo.

Corneal dystrophies80, 81, 82

Corneal dystrophies are a group of bilateral, non-inflammatory disorder of cornea. They are hereditary in nature of varied mode of transmission, however autosomal dominant trait is most common type of inheritance. Exact causes of corneal dystrophies are not known. They may be seen at any age but most of them start in childhood. Some of them may be present at birth. Corneal dystrophies generally involve central cornea, only few extend to the periphery, loss of vision depends upon position of the opacity in relation to the pupil and density of the opacities. Generally there are multiple opacities. Some of the dystrophies have loss of corneal sensation many of them develop recurrent erosion of corneal epithelium, dystrophic cornea do not get vascularised. There is no evidence of any other ocular disease in the affected eye. As corneal dystrophies are relatively uncommon and many of them may not require any treatment hence they are missed most of the time specially in under developed countries where bilateral opacities due to infection, inflammation and malnutrition are very common. All cornea’s with small central bilateral opacities without congestion and anterior segment reaction should arouse suspicion of corneal dystrophy and as many members of the family in as many generation possible should be examined to confirm diagnosis. There is no known medical treatment for corneal dystrophy. Lamellar corneal graft or penetrating keratoplasty or excimer may help to remove the opacities and improve vision. Recurrence of disease in grafted cornea is known.

Classification. Corneal dystrophies are best classified according to topographic location of the dystrophy.

A.Affecting anterior membrane (i) Affecting epithelium

(ii) Affecting Bowman’s membrane (iii) They involve superficial stroma.

B.Affecting stroma

C.Affecting the posterior membrane i.e. Descemet’s membrane and endothelium.

D.Combined

Following are a few common dystrophies that are seen in children.

Anterior corneal dystrophies Commonly seen in children :

1. Hereditary juvenile epithelial dystrophy (Meesmann’s). This is an autosomal dominant disorder, generally seen between 3 to 4 years of age. It has been reported under one year also. Visual acuity is not much reduced the lesions are best seen onretro illumination as micro vescicles in the deeper layers of epithelium. In the inter palpebral fissure corneal sensation is reduced. The disorder progresses very little. If vision is reduced sufficiently to hamper patient’s routine then only lamellar keratoplasty is recommended. The epithelial micro vescicles may raise the epithelium, this causes tear film abnormality. There may be irregular astigmatism. If corneal erosion occurs, which is rare, bandage contact lenses may be helpful.

2.Hereditary epithelial dystrophy (Stocker and Holt). This is an autosomal dominant dystrophy, which is sometimes considered as variant of Messmann’s dystrophy. It starts in infancy, loss of vision varies between slight haze to severe loss due to total opacification of the cornea. The epithelial surface is irregular leading to irregular astigmatism. Corneal sensitivity is sub-normal. Treatment depends upon degree of visual loss. In severe visual loss lamellar keratoplasty is advocated. In both Messmann’s dystrophy and Stocker and Holt dystrophy, anterior stromal puncture along with bandage corneal lens may help epithelisation of erosion. Anterior stromal puncture is generally done by fine needle under magnification. This can also be done by YAG laser. Excimer laser is also used in case of recurrent corneal erosion.

3.Reis-Bucklers dystrophy. This condition is less common than previous two conditions. Inheritance is autosomal dominant. There are two types of this Bowman’s membrane dystrophy i.e. (1) Classical less common variety and (2) More frequent type II. Common age of onset is three to five years. Loss of vision is severe as compared to other anterior dystrophies. Corneal sensation is reduced. Erosion is common. The lesions may lead to central corneal opacification.

Management consist of local instillation of lubricating drop and ointment, hyperosmotic agents and antibiotic agent. Patching of the eye at bed time gives much relief to the patient, which can also be achieved by bandage contact lens. Soft contact lens also helps to reduce irregular astigmatism. Lamellar or penetrating corneal graft is required if—(1) Vision is much hampered, (2) Lesion has reached anterior stroma, (3) There is vascularisation secondary to recurrent erosion.

Excimer laser photo therapeutic keratoplasty helps to ablate the epithelium. This gives much respite from recurrent corneal erosion.

4. Hereditary anterior membrane dystrophy (Grayson-Wilbrandt). This is autosomal dominant dystrophy not seen before ten years of age. There is gradual loss of vision. Corneal sensation remains normal. On slit lamp examination the corneal nerves are found to be thickened corneal opacity may require lamellar keratoplasty.

Stromal Dystrophies in Children

1.Lattice dystrophy (Biber-Haab). Lattice dystrophy is an autosomal dominant disorder that manifest at the end of first decade or early. In childhood vision is good that gradually diminish over years. There may be recurrent corneal erosion. There is gradual increase in corneal opacification that extend from limbus to limbus. The opacities are lattice in nature. The branching opacities may be confused with corneal nerve. Corneal sensation is good initially but gets reduced by third decade. Histochemically the opacities stain with Congo red. In childhood vision is good and does not require treatment. Recurrent corneal erosion in third and fourth decade is treated with artificial tear, lubricating ointment, soft contact lens. The eye may require patching. As the lesion is deep, penetrating keratoplasty is preferred. The donor cornea may develop opacities after ten years. Excimer laser, photo therapeutic keratectomy may help in removal of opacities.

2.Granular corneal dystrophy (Groenouw’s I). The condition has autosomal inheritance, starts in the first decade of life in the central cornea as white granules. Stroma in

between the granules is clear hence initially there is no visual disturbance. The condition is almost symptomless in childhood. Symptoms manifest after fourth decade as irritation photophobia and diminished vision. Corneal sensation is normal. No treatment is warranted in childhood. Penetrating keratoplasty may be required after forty years of age.

3. Macular dystrophy (Groenouw’s II). This differs from most of the corneal dystrophies in being autosomal recessive. The disorder starts round about five years of age as greyish white opacities in the mid cornea that may spread up to limbus and involve the endothelium. By third decade there is troublesome corneal erosion.

Definite treatment is keratoplasty in third and fourth decade. Children do not require any specific treatment. In suitable cases contact lens may help in improvement of vision.

Crystalline dystrophy (Schnyder’s). This dystrophy is seen under ten years of age, may be present in infants. It has been reported at birth. It is autosomal dominant in inheritance. It starts in the centre of cornea as needle shaped crystals. The needles may come together to form a disc shaped opacity. The condition becomes stationary after third decade. There is no vascularisation. Corneal sensation is normal. No treatment is required.

Posterior Dystrophies in Children

Cornea deeper to stroma is less frequently involved in dystrophic conditions in childhood. There are two condition that are seen in childhood. They are :

1.Posterior polymorphus dystrophy.

2.Congenital hereditary endothelial dystrophy.

Endothelial dystrophies are only conditions that may have other congenital anomalies of anterior segment.

Posterior polymorphous dystrophy (P.P.M.D.). This condition is mostly seen at birth, when not associated with other anomalies of anterior segment like lridocorneal dysgenesis, correctopia, lrisatrophy, peripheral synechiae, congenital corneal edema, the condition is almost symptomless, does not cause visual impairment. It is mostly autosomal in nature, rarely it may be recessive.

Congenital hereditary endothelial dystrophy (CHED). This dystrophy manifests before ten years, may be present at birth. There are two forms -

1.Autosomal dominant. This presents in early childhood, progresses slowly but is symptomatic.

2.Autosomal recessive. This is present at birth but non symptomatic, diagnosed on routine examination.

One unique feature of CHED is increased thickness of cornea. Vision may be between 20/40 to CF.

Treatment. Most of the children do not require any treatment. Other associated congenital anomalies should be treated individually.

BCL = Bandage Contact Lens CL = Contact Lens

LK = Lamellar Keratoplasty

PK = Penitrating Keratoplasty PB = Pad and Bandage

CO = Corneal Opacity.

Corneal degenerations83, 85, 86

Degeneration’s of cornea are far more common than dystrophies. They are not genetically predisposed. They can start at any age. They can be unilateral. Bilateral degeneration are secondary either to bilateral ocular disorder like trauma, uveitis or systemic disorder like abnormal calcium metabolism. Commonest type of corneal degeneration seen in children is

Band keratopathy.

Band keratopathy84. (See page 248-249 as well) Band keratopathy can be divided into :

1.Primary (rare)

2.Secondary

A.Secondary to ocular cause

B.Secondary to systemic cause.

Band keratopathy secondary to ocular disorder is commonest form of corneal degeneration seen in children. Chronic uveitis, chronic keratitis, penetrating injury, chemical injuries, congenital anomalies are common predisposing factors. Though it takes months to years to develop band keratopathy, it is reported to manifest within two to three weeks following alkali burn. The band keratopathy itself does not produce any symptom initially. It takes few months to years to be symptomatic. Band keratopathy develops in the inter palpebral fissure. It extends across the cornea in a band shaped opacity which starts from periphery and spread towards the centre, pupillary area is last to be affected. However in rare instance it may spread from centre to periphery. The opacity starts as a linear band one millimetre inside the limbus on either side. The outer edge of the opacity is sharply defined while the inner edge is irregular and serrated. Gradually opacities from each end meet to cover the cornea. There are few areas of deficiency in the opacity. They are called holes. Such holes correspond to corneal nerves. The opacity is caused by extra cellular deposition of non crystalline salts of calcium carbonate and phosphate at the level of Bowman’s membrane and superficial stroma. The epithelium shows no change except that it may be irregular due to underlying deposits.

Corneal sensation is not disturbed. The endothelium is not involved. Anterior chamber reaction when present is legacy of primary disorder i.e. uveitis etc. Exact cause of deposition of calcium at the level of Bowman’s membrane in band keratopathy is not well understood, so is its predilection for exposed part of cornea. In case of band keratopathy secondary to ocular disorders,serum calcium is within normal range.

Band keratopathy has been reported following use of silicone oil, sodium hyaluronate, sodium chordrontin sulphate, phenyl mercuric nitrate. Anterior segment ischaemia produces early band keratopathy. It has been observed in failed keratoplasty.

Band keratoplasty secondary to systemic disorder. Band keratoplasty secondary to systemic disorders are less common than the former. Topography of the opacity is similar in both conditions. In latter the calcium is intra cellular and there is an alteration in calcium and phosphorous metabolism.

Systemic conditions that cause band keratopathy are—Vitamin D toxicity, hyper parathyroidism, uremia, milk alkali syndrome, sarcoidosis, chronic renal failure, hereditary.

Primary band keratopathy. This is rarest form of band keratopathy. There is lack of unanimity regarding its nature i.e. Is it a degeneration or dystrophy ? as there is overlaping of characteristics of both conditions. The condition is X linked recessive trait, present at birth or early childhood. There is no associated ocular disease. Besides cornea other parts of eye like lens, choroid, retina may also be involved. These eyes generally become blind in early life.

Treatment of band keratopathy87. There is no known prophylaxis. However properly managed uveitis, glaucoma and trauma reduce the incidence. In band keratopathy secondary to systemic hyper calcimia, reduction in serum calcium sometimes clear the cornea. Similarly discontinuation of vitamin D. Enthusiastic supply of vitamin D in children should be discouraged.

There are two modes of treatment for band keratopathy

1.Use of a chelating agent

2.Keratoplasty

Treatment is indicated only in symptomatic cases. The success depends upon presence or absence of effect of primary disorder. Treatment of band keratopathy will restore vision only if the cause of defective vision is corneal. In presence of active inflammatory lesion or reactivation of lesion, the calcium deposit may start again.

Use of chelating agent. Method consists of anaesthetising the cornea with local anaesthetic agent. In children the procedure should be done under general anaesthesia. Once the cornea and conjunctiva have been anaesthetised the epithelium is removed by scrapping with any suitable method. The calcium deposit is next scrapped off, the stroma preferably under microscope. A Week-cel sponge is soaked in 0.5% solution of EDTA. This is applied on the exposed calcium deposit, a to-and-from movement helps to remove the deposits better. If 0.5% EDTA fails to produce desired effect the strength of the solution is raised to 1% or 1.5%. Once all the deposits have been removed, the eye is patched with cycloplegic and local antibiotic drops.

The aim of chelation is to remove the calcium without scarring of the stroma.

A lamellar keratectomy or excimer laser photo therapeutic keratoplasty are better options than chelation. Drawback with excimer laser treatment is that it can cause post operative undesirable hypermetropia.

Corneal opacity in new born and infants88, 90. Cornea of a new born is hazier than normal. This haze clears within few days without any treatment and is generally not noticed

by mother or nurse unless looked for. However a child may be born with corneal haze sufficient to be called opacity. A child may have bright and clear cornea at birth but later becomes hazy. Commonest cause is buphthalmos. Corneal haze in new born may be unilateral or bilateral. Commonest cause of unilateral haze is birth trauma. Buphthalmos that is more advanced in one eye may also produce unilateral hazy cornea.

Common causes of corneal opacity are :

The above conditions are acronym as STUMPD89 with beginning alphabet of each cause.

Interstitial keratitis is a common cause of bilateral corneal haze but seen only after third year of life with redness, photophobia and lacrimation.

Xerophthalmia and Keratomalacia91, 92, 93

Logically the term xerophthalmia should include all the conditions that produce non wetability leading to dryness of ocular surface i.e. cornea and conjunctiva. However term xerophthalmia93 is generally used to denote dryness of conjunctiva and cornea due to vitamin A deficiency. Similarly xerosis is a term used for which hypovitaminosis A is the prime cause. There are many other factors that lead to dryness of conjunctiva. Keratomalacia93 denotes softening and aseptic and necrosis of cornea due to deficiency of vitamin A, that is generally preceded by xerophthalmia.

Tear is essential to keep the cornea and the conjunctiva bright and moist. Normal tear has three layers of different chemical composition and each has specific purpose. The layers are—Lipid, aqueous and mucin. Deficiency of any layer will lead to tear film abnormality.

Aqueous layer is voluminous when compared to other layers. It is sandwiched between lipid and mucin layer. The lipid layer prevents excess evaporation of aqueous layer and gives a shinning surface while, the mucin layer anchors the aqueous layer to the cornea and the

conjunctiva. In hypo vitaminosis A there is hyposecretin from goblet cells of conjunctiva. The aqueous and lipid layers are unaffected, lack of mucin causes abnormal break up time resulting in formation of large dry spot on the ocular surface. There is thickening and loss of elasticity of conjunctiva, it may be keratinised which leads to opacification of conjunctiva. There is increased pigment deposit on the conjunctiva that appears as dusty white patch.

Normally the conjunctiva is not thrown into vertical folds when the eye is rotated but in case of dry conjunctiva, the conjunctiva is thrown into three to four vertical folds in the intra palpebral aperture.

The exact mechanism of dryness of cornea is not understood. Lack of mucin hasten tear break up and delayed bridging of the gap. There is degeneration of Bowman’s membrane infiltration of stroma by inflammatory cells and fluid.

Vitamin A is essential for maintenance of conjunctival goblet cells that secrete mucous. Daily requirement of vitamin A varies with age. An infant requires five times more than an adult. An infant requires 65 mg/kg of vitamin A while requirement of adult is 12 mg per kg of body weight that roughly comes to 2500 IU of pure vitamin A or 4000 IU of carotene. Retinol is fat soluble vitamin A, that is of animal origin found in fish, meat, poultry and milk. Carotenes are precursors of vitamin A. It is found mostly in green leafy vegetables, yellow fruits, red palm oil. The carotenes are converted to retinol in the small intestine from where it is absorbed and transported to liver, which is reservoir of vitamin A. The retinol stored in liver is released in blood stream as retinol binding protein, hence systemic protein deficiency may precipitate xerophthalmia if it is not corrected. Retinol besides maintaining health of epithelial cells of conjunctiva also plays an essential role in night vision. Retinol combines with protein in rods and act as light stimulus, exciting the optic nerve in scotopic vision. Vitamin A is involved in photo chemistry of night vision. It is involved in breakdown and resynthesis of rhodopsin. Night blindness sets in when serum vitamin A level falls below 50 IU/L. This may happen in :

1.Reduced consumption

2.Increased loss or

3.Reduced storage in liver.

4.Deficiency of vitamin A responds quickly to administration of water soluble vitamin A by intra muscular injection within twenty to twenty four hours.

Clinical features. Clinical features depend upon severity, duration, associated secondary infection of the eye and systemic infective diseases like pneumonitis, gastro enteritis, measles etc.

Most commonly used classification is that given by WHO94 that divides xerophthalmic signs into two broad groups i.e. primary and secondary signs. Each group has been divided into three sub groups :