Ординатура / Офтальмология / Английские материалы / Pediatric Opthalmology_Mukherjee_2005

The other type is total nuclear cataract that may involve infantile, foetal or embryonic nuclei. The condition is bilateral, symmetrical and stationary may hamper vision.

3. Other cataracts

(a) Sutural Cataracts. These are discrete opacities in the Y sutures of the embryonic nuclei. They are generally bilateral and stationary. One or both the sutures may be involved but need not be symmetrical. A type of sutural cataract seen in premature children are known to fade by third month post natal19. Other variants are : Floriform, (Coralliform) and anterior axial cataract.

(b) Blue dot Cataract. This is very common congenital anomaly of lens. The opacities of various sizes, some of them visible only with slit lamp, others may be visible with bright oblique illumination. The opacities are scattered in the centre of the lens. They are not really coloured blue, they are white but due dispersal of violet light20 they look blue. The opacities do not hamper vision, do not cause any complication hence do not require any treatment.

(c) Membranous Cataract. These are not separate type of cataracts. They result due to absorption of soft cortical matter in congenital cataract of long standing spontaneously or following trauma . The two capsules come close to each other with some opaque lens fibres in between without nucleus. They generally do not require any surgery but thick membrane may be needled folled by standard correction of aphakia.

RUBELLA CATARACT

Rubella cataract is caused by systemic infection of the mother by rubella virus in first trimester. Infection acquired after first trimester have very less chances of causing congenital defects in the foetus and subsequent pregnancies are not effected by the earlier infection. The rubella virus belongs to a group of toga viruses and has single antigenic type21. The virus is found all over the world with pockets of endemic areas, and can be prevented by prophylactic vaccine given in school going age. There is no antiviral agent known to be effective against rubella virus. The virus passes to the developing foetus via placenta and affects organogenesis of multiple organs, main being eyes, ear and heart. The infected mother has 50% chances of having child with congenital anomalies half of them will have ocular involvement12. The systemic manifestations in infected mother are mild and passed off as common cold with enlargement of occipital lymph glands.

In utero the virus causes cells to have increased doubling time and short survival time. The growing lens develops areas of necrosis that loose transparency.

The rubella cataract is central dense opacity to begin with, which becomes pearly and spreads to cover whole of the lens and may loose fluid later to become membranous. Hence in all cases of congenital membranous cataracts possibility of rubella should be kept in mind. The virus remains alive in the lens for months, may be as long as three years22 and when liberated in aqueous following surgical or accidental trauma is likely to cause sever and long lasting uveitis that it self may be sight threatening.

Congenital rubella cataract is part of a syndrome of triad that consist of

A.Congenital cataract

B.Neurosensory hearing loos

C.Congenital heart disease.

Besides cataract there are other congenital anomalies of the eye they are :

Microphthalmos, rubella retinopathy, iris hypoplasia, transient corneal haze.

Congenital glaucoma is a common feature with congenital rubella cataract but is independent of pathological process of cataract formation.

The systemic manifestation besides heart disease and neurosensory hearing loss are many. The neurosensory hearing loss is not always present at birth but may develop in preschool age. Bone lesions, hepatitis, thrombocyotopaenic purpura, hemolytic anaemia and occasional central nervous system involvement are infrequent systemic manifestation. Congenital rubella is known to cause still birth, prematurety and mental retardation making the management more difficult.

D. Management of rubella Cataract

1.Prophylaxis in mother : Rubella is fully preventable disease following rubella vaccination between 12 to 14 years of age. If rubella vaccination is made part of universal immunisation the scourge of rubella syndrome with its morbidity and mortality can be abolished altogether.

2.There is no known medical treatment for the infected mother or child..

3.Only definitive treatment of congenital cataract of (a) Surgical removal of Cataract (b) Management of aphakia (c) Prevention and treatment of amblyopia, squint and nystagmus (d) Associate glaucoma requires separate management.

CONGENITAL AND DEVELOPMENTAL CATARACTS DUE TO INBORN ERRORS OF METABOLISM CONSIST OF

A.Galactosaemia

B.Hypoglycaemia

C.Diabetes mellitus

D.Homocytinuriaand other amino aciduria (Low’s Syndrome)

E.Hepato lenticular degeneration (Wilson’s disease)

F.Hypoparathyroidisionm.

A. Galactosemia

Galactosemia is one of the inborn errors of metabolism that causes developmental cataract. Galactose is not available separately as source of food. It is a metabolic product of lactose which is an important carbohydrate content of mammalian milk. The other source being endogendus in form of neurolipids in small quantity. The lactose is hydrolyzed in to glucose and galactose in the intestine, galactose itself is converted into glucose. In galactocemia

this conversion of galactose to glucose is hampered due to deficiency of one of the three enzymes required to complete the metabolic cycle. A sugar alcohol that is responsible for cataract formation is formed that on entering the lens fibres cause a state of hypertonicity which attracts water to neutralise the alcohol leading to swelling of lens of fibbers, and opacification of the lens.

The three enzymes involved in galactose metabolism are Transferase, galactokinase and epimerase.

Commonest being transferees deficiency the epimerase deficiency is extremely rare.

Transferase deficiency galactosemia is so frequent among other galactosemics that it is called Classical galactosemia The ocular components consists of bilateral central cataract also known as oildropelet cataract due to its appearance. The first change may be posterior lenticonous that on examination under slit lamp within few days of birth, show refractile opacities in the centre of the lens. Concentric refractile rings may develop round the central opacity. The opacity may initially look like a zonular opacity with clear zone all round. The opacity spreads rapidly to cover whole of the lens within few months. The progress of the opacity can be stopped or altogether reversed if milk and milk products are fully eliminated from the infants feeds.

The systemic changes are serious and even life threatening they consists of vomiting, diarrhoea hepatospleenomegaly, hepatic and renal dysfunction, cirrhosis, anaemia, failure to gain weight, mental retardation.

Glactokinase deficiency galactosemia is rarer than the former it is more benign26 has no systemic changes. The infant is healthy, the cataract develops in first few years of life. The cataracts are central and bilateral, their natural history is similar to transferase deficiency cataract except that kinase deficiency cataract is slower than the former.

1. Diagnosis of galactose cataract consist of

(a) Clinical examination of the new born with diarrhoea, vomiting, dehydration and hepatio spleenomegaly

(b) Examination of urine for reducing substances.

(c) If reducing substances are present the urine should be examined for osazone crystals which are absent in galactosemia to exclude diabetes. The urine is subjected to chromatography for specific band denoting galactosemia, other specific tests consists of

(d) Estimation of urinary and serum galactose.

(e) Assay for uridyltranasferase in peripheral red cells. (f) Urine examination for albumin and aminoacids. (g) Hepatic function test.

2. Management. As soon as it is conformed that the child has galactosemia all mammalian milk products are withdrawn from the diet. This may retard or reverse the opacity. If opacity persists it is managed by any of the standard procedure.

lens gradually increases to adult size in the second decade. There is no condition where the lens has congenitally larger diameter Microspherophakia29 is a congenital anomaly of the lens where the average diameter of the lens is 6.75 as against 9mm of an adult lens. The anterior posterior diameter of the lens is 25% more than normal. Reduced equatorial diameter and increased thickness of the lens gives it an appearances of a spherical lens with small diameter hence the name microspherophakia. The condition is bilateral. The child is brought due to diminished distant as well as reading difficulty. The cornea is of normal size so is the globe. The anterior chamber may be deep on the periphery with mild iridodonesis the real diagnosis is made on dilatation of the pupil. With a widely dilated pupil the periphery of the lens gives a crescent like reflex. On retinoscopy the central part shows high myopia with or without astigmatism. On slit lamp examination the zonules are visible all round in early years but later on there may be rupture of some of the zonular fibres, resulting is subluxation which is common. A peculiar phenomenon called glaucoma inverse results if the pupil is constricted either due to prolonged exposure to bright light or use of miotic. The spherical lens obstructs the miotic pupil resulting in pupillary block and rise of tension. There may be associated angle closure. The tension falls with mydriasis. The lens may occasionally come in the anterior chamber. Generally there are no other congenital anomalies of the globe. The condition may have only ocular component or may be associated with systemic anomalies resulting in Weill-Marchesani syndrome. The exact cause of the deforming is not known. It is presumed that it results due to arrest of development of lens during 5th or 6th month of gestation.

Management of the condition is difficult due not only to index myopia, poor accommodation but also secondary pupillary block glaucoma. Besides correction of index myopia a constant watch should be kept on possibility of pupillary block. Prophylactic iridectomy or iridotomy, may prevent rise of tension, use of mydriatic is better avoided because the lens may subluxate in the A.C.. Cataract is common and should be managed like any other cataractus ectopia lentis.

CONGENITAL ANOMALIES OF SHAPE OF THE LENS

There are two types of anomalies of shape of the lens due to congenital cause.

A.Lenticonus.31

B.Coloboma of the lens.

A. Lenticonous is a condition where the poles of the lenticular capsule bulge out side the confines of the capsule. If the projection is anterior where the lens bulges in the anterior chamber the condition is called anterior lenticonous and when similar changes appear in the posterior capsule with bulge extending into the vitreous the condition is known as posterior lenticonous. The terms lenticonous and lentiglobus are used as interchangable terms.

Posterior lenticonous is more common. The cone is situated within 5mm of the posterior pole, however it can be eccentric or peripheral. There is a very rare condition where the posterior cortex develops a local bulge with in the confines of the capsule32.

speherophakia. 2. When the defect is localised the result is a coloboma of the lens, where the lens does not subluxate 3 when the defect is excessive on one side the lens gets sub luxated to the opposite direction 4. if the zonules are lacking all-round the lens is dislocated.

CONGENITAL ANOMALIES IN THE POSITION OF THE LENS

A. Ectopia lentis

Next to cataract, displacement of lens is most common congenital anomaly of the lens. It may be mild enough to be missed unless examined with slit lamp under complete mydriasis. The congenital displacement is generally bilateral and nearly symmetrical most of the time the displacement of the lens in the one eye is mirror image of the fellow eye.

1. A lens is said to be ectopic when

(a) Its centre is not in the anterio posterior axis of the eye.

(b) Some of the zonule are still attached to the lens.

(c) The lens is behind the iris. (d) Partly visible in the pupil.

(e) The edge of the lens in the pupillary area dividing the pupil into two parts:- one phakic which is generally myopic and the other area aphakic that is hypermetropic.

2.A lens is sub luxated when some of the zonules are still attached to the lens capsule.

3.A lens is dislocated when all the zonules are severed from the lens and the lens can move in the

(a) Anterior chamber

(b) Incarcerted in the pupil (c) Bobbling in the vitreous

(d) Fall at the bottom of the vitreous (e) Get fixed to the retina.

Unilateral ectopia is rarely congenital it is mostly due to trauma or other ocular causes like chronic uveits . In all cases of unilateral ectopia lentis the other eye should be carefully examined for subtle signs of ectopia, and systemic cause of ectopia lentis ruled out.

B. Symptoms of ectopia lentis depend mostly on

1.Area of the lens present in the pupil,

2.Tilt of the lens,

3.Transparency of the subluxated lens

4.Associated error of refraction and

5.Complications like amblyopia, glaucoma, retinal detachment.

6.Associated systemic condition.

C. The symptoms can be divided into

Mild, moderate, gross and associated complications.

1.A lens that has subluxated but its edge lies in between the pupillary margin and iris root may not produce any visual symptom, may have normal accommodation of the age. Occasionally there may be diminished vision due to errors of refraction independent of subluxation, or due to subluxation i.e. myopic astigmatism.

2.A lens that divides the pupil in two halves, one aphakic and other phakic causes moderate visual symptoms of unilateral diplopia and fleeting visual disturbances. The phakic part is myopic or myopic astigmatism with accommodation. The aphakic part which is hypermetropic and has both diminished distant as well as near vision. Bilateral moderate subluxation may cause polyopia.

3.The edge of a subluxated lens that is not visible in undilated pupil causes gross loss of distant as well as near vision without diplopia because the whole of the pupillary area is uniformly absolute hypermetropic.

4.Ectopia lentis with associated complication have various grades of visual loss due not only to ectopia but also associated lesions like glaucoma, retinal detachment etc. (See below)

D. Signs of Ectopia lentis consist of

1. Diminished distant vision that may or may not be fully corrected by glasses or contact

lens.

2.Diminished near vision

3.Uniformly or partially deep A.C.

4.Generalised or localised tremulousness of iris

5.Pupillary shape and size are variable, depending upon other associated and anoma-

lies.

6. The edge of the lens may give a crescent shaped reflection on retinoscopy; the phakic area is myopic whereas the aphakic area is hypermetropic.

7 On fundus examination—doubling of the fundus i.e. a large area seen through the phakic myopic area and a small area of fundus seen through hypermetropic area.

8.The refraction may not be symmetrical and equal in both the eyes.

9.The eye invariably has strabismus in unilateral cases and also when the refraction is grossly different in both the eyes.

10.On slit lamp examination the zonules may be visible in the aphakic area and vitreous may herniate though the aphakic area.

11.Complication

(a) Raised intra ocular tension (b) Myopic degeneration

(c) Rhegmatogenus retinal detachment

12.Associated anomalies

(a) Mesodermal dysgenesis of anterior chamber (b) Megalocornea.

(c) Cornea plana

(d) Persistent primary hyperplastic vitreous (e) Retinitis pigmentosa

(f) Congenital glaucoma. (g) Keratoconus

(h) Ectopic pupil (i) Aniridia

(j) Ptosis.

13.Associated systemic anomalies (a) Marfan’s syndrome.

(b) Homocytinuria.

(c) Weill Marchesani syndrome (d) Reiger’s anomaly

(e) Crouzon’s syndrome (f) Oxycephaly

(g) Hyperlysinemia

(h) Sulphite oxidise deficiency (i) Ehlers - Danlos syndrome (j) Mandibulo facial dysostosis. (k) Sturge Weber syndrome.

SIMPLE ECTOPIA LENTIS

Simple ectopia lentis represents isolated ectopia without any other ocular or systemic disorder. It is generally familial, transmitted as autosomal dominant inheritence.35 It may rarely be sporadic, the lens is subluxated up and out. On set of subluxation is gradual and may go unnoticed unless looked for specifically in a child with positive family history or the child is brought with complaints of diminished vision or squint. They generally have good distant as well as near vision for many years but may develop anterior dislocation, glaucoma, cataract or retinal detachment36.

ECTOPIA LENTIS et PUPILLAE37

This is transmitted as autosomal recessive inheritance, is bilateral symmetrical, the normal pupil is replaced by a slit like or oval opening complete with constrictor and dilator muscles, the pupil is shifted opposite the shift of the lens i.e. if the lens is displaced up and out , the pupil is shifted down and in. The edge of the pupil generally bisects the pupillary slit. The angle of anterior chamber is clear. The condition may be considered as mildest form mesodermal dysgenesis.

MARFAN’S SYNDROME38,39,40

Marfan’s syndrome is an autosomal dominant disorder of mesodermal tissue with multi systemic involvement. It is seen equally in boys and girls with world wide distribution. Though the condition beings in infancy its full blown presentation is felt in teens. It has been reported to run in generations and common among the siblings. The disorder does not have any biochemical deficiency that may be linked to the anomaly. The syndrome has following component, all of which need not be present simultaneously:–

A.Ocular

B.Skeletal

C.Cardiovascular

D.Miscellaneous

A. Ocular

Most important, frequent and prominent ocular changes are seen in thelens. The changes are bilateral almost symmetrical.

1.The lens. The lens is subluxated upwards in both eyes; they are mirror images of each other. The subluxation is gradual but does not progress much. Occasionally the subluxation may increase and the lens may even dislocate apparently without any reason. Common predisposing factor being trivial blunt injury, subluxation may occur at any age. The lens is generally clear but may have localised opacification at the lower equator. Generally the lens is slightly smaller in diameter it may be microspherophakic. It is usual for patient to have normal accommodation for the age but if the subluxation is more i.e. the aphakic portion covers lower half of the undilated pupil, the child has difficulty in near work. The subluxated lens gives a crescentic dark reflex on oblique illumination due to reflection of light from rounded edge of the clear lens.

2.On retinoscopy the phakic area generally gives a compound myopic astigmatism while the aphakic portion has hypermetropic refraction generally less than +10D.

3.On ophthalmoscopy duplication of fundus is seen. The fundus seen from the phakic area is generally larger while seen through the aphakic area is smaller than emmetropic fundus. The eyes commonly have axial myopia with corresponding myopic fundus changes.

4.On slit lamp examination the zonules are visible some of them may be broken, the lens rarely shows a scalloped lower border or a notch.

5.The anterior chamber is irregularly deep, deeper over the aphakic part and shallow or normal over the phakic part. The lower iris is generally tremulous, occasionally there is phacodonesis.

6.Pupil. The pupil is smaller than normal due to poor development of dilator fibbers. The pupil is resistant to usual mydriatic and cycloplegic. The pupil retains normal light and near reflex.

7.Iris. The surface of the iris is relatively smooth.

8.Angle of A.C. Gonioscopy shows wide angle with multiple changes that include ill defined Schwalbe’s line.