Ординатура / Офтальмология / Английские материалы / Pediatric Opthalmology_Mukherjee_2005

1.The eye of an infant is small and changes rapidly with age.

2.The visual system of a child is immature and likely to suffer irreversible damage if the macula does not receive sharp image of the outer world. Nystagmus and amblyopia develop fast in infancy and child hood.

3.All the opacities are not of uniform nature as regards density and position hence a uniform protocol can not be advised for all cases.

4.Cataracts in childhood may be associated with anomalies of other intra ocular structure that hamper improvement of vision.

5.Cataracts may be associated with larger systemic syndromes including errors of metabolism.

6.The child has a long life to live that includes education, vocational training, choice of profession where diminished vision, diminished accommodation, loss of peripheral field and appearance may be some of the hindering factors.

7.There is not medical treatment for cataract60.

8.Scope of prophylaxis is limited to rubella.

9.Genetic counselling is not always possible.

10.Definitive treatment is surgery which requires high degrees of skill and effi-

ciency.

B. Various modes of management available for paediatric cataracts

1. Prophylaxis

(a) Prophylaxis is limited to rubella cataract and to some extant galactosemic cataract. If every girl in school going age receives a shot of rubella prophylaxy as part of national immunisation, the danger of rubella cataract can be wiped out altogether. It should be kept in mind that rubella is not only a blinding disease it is also a crippling and some times a fatal disease.

(b) In galactosemia, removal of milk products from the child’s diet will not only remove the possibility of child developing cataract but may improve transparency of the lens.

(c) Trauma as a cause of cataract requires involvement of parents, teacher and social workers. Children should be explained about possibility of blindness by sharp objects like spears, arrows, and catapult, tipcats.

2. Non-Surgical

This depends on presence of useful clear zone between the pupillary border and periphery of the opacity. A small opacity that does not cover the whole of normally acting pupil does not require any treatment including mydriasis which is required when the opacity covers the entire normally acting pupil but has useful clear zone when dilated. These are generally various types of zonular cataracts the regime consists of keeping the pupil dilated with lowest dose of atropine that gives maximum mydraiasis. Atropine has a draw back that it abolishes accommodation that is an important factor for learning, in children .These children under atropine may be provided with near correction. Dark glasses during day may also serve in limited way. The children should be taught to sit with back towards the light and light falling on the books.

3. Surgery

Surgery is the definitive treatment for all paediatric cataracts. Lensectomy with IOL is the standard procedure for most of paediatric cataracts, IOL is with held only when its placement is not possible. In such cases Lensectomy followed by contact lens, spectacles or epikeratophakia are some of the alternatives available. The aims of surgery are to preserve vision, prevent amblyopia and maintain fusion as far as possible.

IOL in Children

Older children can tolerate P.C.I.O.L as much as adults. Till few years ago it was thought that intra ocular lens be implanted only after 2 years of age50 Now a days, implanting a lens within 48 hrs of birth is considered safe47,49.

Some of the anatomical difficulties in implanting IOL in children are

1.The eye ball is small in all dimensions.

2.Comparison between various dimensions of a new born and adult eye is given below :

3.The child’s axial length will reach its adult size by seven years. At 2 years it is about 20mm51,52 and at four years it is 22 mm.

4.An IOL of 32D will be required to make an eye of a new born (axial length 16.5mm) emmetropic. But this is not correct because the axial length of the child will be as much as 21 to 22mm at 3 to 4 years of age, which, with an IOL of 32D will make it myopic by 8 to 10D. This amount of myopia reduces the distant vision greatly. The most ideal choice will be to use an IOL that will make the eye slightly myopic. This will give a comfortable near vision as well.

5.The other difficulty faced is difficulty in calculating IOL power in children below 2year of age. For accurate reading this has to be done under general anaesthesia which by it self is a highly specialised discipline.

6.Next difficulty is to decide when to implant an IOL. Children with dense opacities, where no part of the fundus is visible under maximum mydriasis should be operated as soon as the child may under go general anaesthesia for considerable time. In bilateral cases lensectomy is followed by IOL implant, otherwise a simple aphakia is left to be corrected by, spectacles, contact lens, and epikeratophakia. The last method has been given up in favour of secondary implant. It is better not to operate both the eye at the same time.

7.Unilateral cataracts of all densities have uniformly poor visual prognosis.

8.If the discs in both eyes are visible, are of normal colour, elevation and size, both maculae are visible with out any abnormality chances are that vision in both eyes are equal. The child should be watched for evidence of increase in size of opacity. An opacity larger than 3 mm requires removal. If the opacity is stationary the eye can be atropinised and bifocal prescribed when the child starts schooling.

9.If there are evidences suggestive of asymmetry in vision, amblyopia must be treated vigorously.

10.Presence of nystagmus is always a very poor prognostic factor. It generally develops by two month in case of congenital cataract.

11.Next problem is to decide which type of lens should be implanted. A.C. IOL are out of question because of high rate of complication. It is better to leave an eye aphakic rather than pseudophakie with A.C.IOL.

In majority of cases P.C.IOL are put with satisfactory results. Of course there is a school of thought that considers the infants eye to be too small and too immature to put a P.C.IOL because except an iris claw lens all lenses are over sized for the placement and fixation14,47 and recommend an iris claw lens with maximum width of 6mm to 7 mm with optics of 4mm.

Many of the pediatric aphakics need secondary lens implant, if the posterior capsule is intact. An iris claw lens may be put even in a partially absent posterior capsule.

4. Other methods of management of aphakia in children

Commonest cause of aphakia in children is surgical removal of lens. Other causes are spontaneous absorption of a congenital cataract due to posterior leak or absorption following penetrating wound. There may be traumatic dislocations or spontaneous dislocation in buphthalmos, megalocarnea or chronic uveitis.

Aphakia in children is managed by (a) Spectacles

(b) Contact lens

(c) Secondary implant (d) Epikaratophakia

(e) Combination of more than one method.

(a) Spectacles. Spectacles in children are generally prescribed in all ages more for economic reasons than its optical efficiency in developing countries. Its advantages are: It is cheap, easy to manage, gives fairly good distant vision, bifocals may suffice for near vision. If power is equal in both eyes chances of amblyopia is reduced. They are not very suitable for unilateral alphakia because the child with good vision in other eye prefers normal single vision with out glasses and if the child is forced to wear them, have a tendency to look over the frame. This negating the optical advantage of spectacle.

(b) Contact lenses49. Contact lenses are best alternative to IOL, some surgeons fit contact lens just after the lensectomy, others prefer to fit extended bear lens after 10 days. Hard contact lenses are difficult to insert due to tightness of the lid, strong blink reflex, frequent displacement of lens and expulsion of the contact lens. All the parents can not be taught to insert them. Up to age of six daily wear or extended wear contact lenses may be tried. Once the child can manage the contact lenses gas permeable lenses may be prescribed.

(c) Combination. Contact lenses do not give use full near vision. They are given near correction in the form of spectacles. Some time spectacles may be required to correct residual power over contact lens or IOL.

AFTER CATARACT53, 54, 55

A.After cataract is not a true cataract. It is the after math of rupture of lenticular capsule with partial absorption of cortex, opacification of posterior capsule with proliferation of lens fibers. In milder form it is also known as posterior capsular opacification or simply P.C.O. Almost all eyes develop P.C.O. following rupture of lens capsule that may be surgical, accidental or spontaneous. P.C.O. is by far denser in children than in adults. It is a major cause of gradual lowering of vision following uneventful I.O.L. implant.

B.Common symptoms of after cataract are

1.White reflex in pupil which may be faint enough to be seen with magnification or denser that is visible in diffused light

2.Non improvement of vision

3.Frequent change of refraction.

Common surgical procedures that result in after cataract are extra capsular cataract extraction, micro surgical extra capsular cataract extraction with or without IOL phacoemulsification, needling aspiration of soft cataract. Rarely injury to lens during vitrectomy may also result in after cataract formation.

Incidences of after cataract depends upon :

1.Age of the patient : almost all aphakic children following extra capsular lens extraction develop PCO.

2.Duration following lens extraction : may develop soon after if coxtex has not been removed well. Most of the children will develop PCO with in one year.

3.Amount of cortical matter left,

4.Placement of IOL and type of IOL,

5.Associated pre existing uveitis

6.Management of post operative uveitis.

C. Mechanism of after Cataract Formation

The posterior capsule of lens is devoid of epithelium. The anterior capsule is lined by cuboidal cells up to beginning of the equator where the cuboidal cells get elongated gradually and are converted in to lens fibres.

In an extra capsular cataract extraction following capsulotomy as much of cortex as possible is removed, yet some of the fibres are left behind, that continue to proliferate as opaque fibres, these opaque fibbers may spread over the posterior capsule, may proliferate as globular bodies or may be entrapped between the anterior and posterior capsule. The first is called simple P.C.O the second, Elschnig’s pearl and the last Soemmerring ring.

The after cataracts besides lens fibbers also contain pigments, exududate and blood in the initial stages. Elschnig’s pearls are formed due to proliferation and migration of epithelial cells to form a fish spawn like small white translucent bodies. The size varies from pin head to 2–3 mm in diameter. They are generally seen in the pupillary area. Their numbers vary from single to many. Dilatation of pupil may expose more.

Soemmerring ring is doughnut shaped ring opacity. This is formed due to adhesion of anterior capsule to posterior capsule entrapping cortex as well as equatorial epithelial cells. The ring is generally hidden behind the iris and visible only with mydriasis, the space inside the ring has fainter P.C.O. The ring may occasionally be dislocated in the anterior chamber.

Incomplete capsulotomy as was fashion in traditional operation for congenital and traumatic cataract resulted in thicker after cataract than present day microsurgical capsulorrhexis. Continuous curvilinear capsulorrhexis cause less P.C.O than canopener capsulorrhexis.

Posterior capsulorrhexis is done routinely with or without anterior vitrectomy in children to reduce P.C.O. Lens extraction with out P.C. IOL causes more opacity than with P.C.IOL. A biconvex IOL or a lens with posterior convexity also lessens P.C.O. Heparin coated IOL or heparin used in irrigating fluid diminishes chance of after cataract. Occasionally the posterior capsule develops wrinkles this causes, stretch lines on the posterior capsule resulting in fluctuating vision and glare.

Capsule contraction syndrome is caused due to contraction of anterior capsular opening this is more common if the eye has suffered from uveitis in the past.

Bacteria of low virulence like propionibacteriumacnes and staphylococcus epidermis45 may be entrapped in the capsular sac and cause capsular opacification with out causing endophthalmitis but may cause endophthalmitis when released following capsulotomy.

D. Clinical Features of aftercataract depend upon

Location of opacity, density of opacity, age of the patient, time lapse after surgery, and associated uveitis.

Pre School children do not complain of diminished vision, they have to be tested for vision, and examined for amblyopia strabismus and nystagmus. On set of nystagmus in infants following surgery means that vision has not improved. This generally happens if the child is less than two years of age.

In dense after cataracts the parents complain that cataract has not been cleaned well or has developed again.

E.Signs consist of white reflex in pupillary area. When examined under mydriasis with slit lamp shows various grades of opacity ranging from translucent to dense white membrane. There may be gaps in between. Other features observed are Elschnig’s pearls, Soemmerring ring and posterior capsular traction lines.

F.Treatment

1.Best treatment of after cataract is its prevention or reduction in its density. It must be remembered that cent percent children develop some degree of P.C.O. that can be prevented by posterior capsulorrhexis with anterior vitrectomy, large capsulorrhexis, use of biconvex IOL and use of heparin coated IOL. Most important thing is to remove as much of cortical matter as possible during the initial surgery. The post operative uveitis should be managed promptly.

2.Once the after cataract has developed and is dense enough to cause reduction in vision it should be cut either surgically or by laser.

3. Laser capsulotomy by N.D. YAG is the treatment of choice.

(a) The indications of laser capsulotomy are diminished vision, monocular diplopia, glare, to facilitate intra-ocular examination and other manipulation.

(b) Relative contra indications consist of

(i) Clear view of fundus by direct ophthalmoscope through the centre of the pupil, because if observer can see the fundus, the observed eye should also be able to see. Otherwise other causes of non improvement of vision such as cystoid macular oedema, amblyopia, retinal detachment, vitreous bands and chronic endophthalmitis should be looked for

(ii) Central corneal opacity (iii) Corneal oedema

(v) Already existing glaucoma and cystoid macular oedema. (v) Peripheral retinal degeneration.

(vi) Unwilling parents of the child and uncooperative child. (vii) Glass I0L

The laser capsulotomy is done either in normal or semidilated pupil

Complications of laser capsulotomy

1.Cystoid macular oedema or worsening of cystroid macular oedema

2.Transient rise of IOP

3.Rhegmatogenous retinal detachment.

TRAUMATIC CATARACT IN CHILDREN

General Consideration

Trauma accounts for 80% of cataract in paediatric age group. They are less common in first three years of age, incidence gradually rises as the child grows. Most of them are unilateral however blast injury, cracker injury and chemical injuries, electric shock, radiation can cause bilateral traumatic cataract. Domestic injuries are commonest cause in younger children while sports injuries are more in older children. Ninety percent of injuries are avoidable. Traumatic cataract have better visual prognosis than congenital and developmental cataract even when they are uni-ocular specially if traumatic cataract occurs after development of binocular vision. Posterior segment and retinal involvement remain major cause non improvement of vision.

Injuries commonly associated with traumatic cataract are: Penetrating injury with or without retained intra ocular foreign body, blunt injury, chemical injury, electrical injury and radiation.

Penitrating injuries do not involve lens in isolation they are associated with corneal, corneo scleral or scleral injuries. Penetrating injuries passing through pupil generally have centre corneal scar and injury to the lens with out injury to iris, but it is common to find iris incarcerated in the wound, otherwise injury to iris and or ciliary body is very common.

Small penetrating injuries

Depending up on the size of the penetrating injury the cataract may be localised if the wound is small and heals fast otherwise complete, if the capsular wound heals quickly. These injuries are generally caused by sewing and knitting needles, nibs, pins, sharp long thorns etc. These small opacities are generally stationary.

Large penetrating injuries cause

1.Total opacification in short time that may cause swelling of the lens, shallowing anterior chamber and glaucoma if the cortical matter does not leak.

2.If the capsule ruptures and the opaque cortical matter spills out of the capsular bag it may fill the entire anterior chamber.

3.If the external wound still leaks the eye remains soft.

4.With a watertight wound the tension may rise resulting into secondary glaucoma.

5.If there is associated zonulolysis : sub luxation or dislocation of cataractous lens. In such conditions vitreous may herniate through the aphakic area, some times the cortical matter gets mixed with vitreous.

6.Prolapse of uvea is common.

7.There may be associated hyphema.

8.There may be irido dialysis, chroidal repute or retinal detachment.

9.IOFB are common.

Lenticular changes following blunt injury are less dramatic than penetrating injuries. Blunt injury may cause small, faint, discrete opacities that may fade with time. It may be permanent and stationary or may spread over the years. Both contusion and concussion can cause traumatic cataract. These closed globe injuries do not cause incarceration of the uvea. The uvea may suffer the effect of blunt injury along with lenticular changes that always hampers future vision.

For traumatic cataract to develop there should be some damage to any part of lens capsule that allows aqueous to reach the cortex. This hydrates the cortex, which converts soluble protein into insoluble protein and leads to ultimate opacification

Opacities may be:

1. Transient, static or progressive.

2. Localised as discrete punctate spots, rosette shaped or scattered subepithelial opacities.

3. Rarely may be total.

Rosette cataracts

Rosette cataracts are common in blunt injuries. It can occur early or late.

Early rosette cataract develops with in few days of blunt injury. It develops in the posterior cortex as opaque lines radiating from a central point, each line has feathery appearance due to finer linear opacities radiating from its trunk giving a star like appearance. There is a clear zone between the opacity and the equator of the lens.

Late rosette cataract develops in the posterior cortex one to two years after the injury that may have been trivial and forgotten.

Vossius ring is not a cataract but is a common effect of blunt closed globe injury where black pigments are imprinted on the anterior lens capsule in a circular fashion. The deposits on the lens capsule correspond to constricted pupil. These are transient and may be confused with post inflammatory pigment on the lens capsule. They fade out over months some times leaving behind faint subepithelial opacities.

Other uveal injuries associated with concussion and contusion cataract are:

Hyphema, rupture of sphinter, iridodialysis, recession of angle of anterior chamber, choriodal haemorrhage, choroidal rupture, retinal haemorrhage, retinal detachment and Berlins oedema. All of them may have adverse effect on visual improvement of vision.

D. Symptoms of traumatic cataract may be

1.Acute following penetrating injury in the form of loss of vision, lacrimation, photophobia, with or without rise of tension.

2.Concussion cataract may cause diminished vision after days or months.

3.Diminished vision weeks after blunt injury is seen in early rosette concussion cataract.

4.Late rosette cataracts cause gradual loss of vision after months.

5.No appreciable visual loss is seen in Vossius ring, punctate opacities, localised opacities away from pupil.

6.Unexplained pain in a closed globe with cataract denotes rise of intra ocular tension.

7.Faulty projection should warn about possibility of large retinal detachment.

8.A penetrating wound should always arouse suspension of intra ocular foreign body.

9.Injury with organic matter like thorns, twigs may present as endophthalmities.

E. Investigation

1.The first and fore most investigation is careful history taking. In case of penetrating injury the child can not hide the history of injury but may not come out with the truth about the circumstances leading to injury and the offending object causing injury. The child may altogether withhold history of blunt injury.

2.Careful examination of vision in both eyes should be under taken in all cases of injury. In infants, pupillary reaction and projection of light gives a gross assessment of vision. Examination of vision has not only diagnostic and prognostic value. It has far-reaching medico legal value.

3.Examination of media by oblique illumination, retinoscope, direct and indirect ophthalmoscope, slit lamp should be done when ever possible. They will give information regarding status of posterior chapsule associated uveitis, subluxation of lens, type and extant of lenticular opacity, state of vitreous, Berlin’s oedema, cystoid macular oedema, choroidal tear, retinal detachment, retained intraocular foreign body, vitreous haemorrhage etc.

4.In opaque media when fundus is not visible, the first investigation ordered should be x-ray of the orbit. If the x-ray shows retained intraocular foreign body, it should be localised, using any of the standard method and foreign body extracted. Ocular ultrasonography C.T and M.R.I are useful to visualise small, I.O.F.B. vitreous haemorrhage, endophthalmitis, retinal detachment, and posterior perforation of globe. However USG may not resolve foreign bodies

less than 2 mm. For such a small foreign body CT is more suited as it can detect bodies as small as 1.06 mm3. Glass fragments are visible only when they are as large as 1.5mm3.MRI is generally not used in suspected metallic foreign bodies because movement of metallic foreign bodies during MRI can result in MRI induced blindness56.

Management

Management of traumatic cataract in children does not differ basically from adult traumatic cataract but there are some special features that need to taken into consideration. which are :

1.Development of amblyopia and squint.

2.Difficulty in management of resultant aphakia in traumatic cataract.

3.Difficulty in placement of IOL.

4.Frequent development of P.C.O. in children.

The management of traumatic cataract in children

1.Prevention: The best management is prevention. It is easier said than done. Parents should see to it that children do not play with pointed objects. The teachers and coaches should be instructed to encourage the children to use standard protective gears when ever required in sports and games.

2.Management of other injuries.

3.Surgery of cataract. Traumatic cataract is very often complicated by corneal, corneo scleral injuries along with damage to uvea, vitreous, retina in various combinations. These injuries are caused due to penetrating injuries. If the lens is already opaque it should be removed along with repair of above injuries as primary process with reconstruction of anterior segment. It may require vitrectomy. Most of the time it is not possible to put a PCIOL in such cases. Presence of central corneal opacity always jeopardises visual improvements.

Simple traumatic cataracts are generally due to blunt injuries or small penetrating injuries of the lens with other tissue intact. These are managed by lensectomy, anterior vitrectomy and primary P.C.I.O.L implantation.

OTHER FORMS OF CATARACTS IN PAEDIATRIC AGE GROUP

A. Steroid induced cataract

Steroids when used for long time locally or systemic have profound side effects. Two common vision threatening conditions are cataract and glaucoma. Longer and stronger the steroids used more are the chances of development of the cataract. Exact duration and strength that causes cataract is not known, perhaps it is influenced by genetically determined factor. Reduction in concentration, frequency, and duration can arrest progress of cataract formation but does not reverse the process. Children are more prone to develop steroid induced cataract than adults.