MANAGEMENT OF PEDIATRIC CATARACT..

Dr. Bhushan Patil

Childhood cataracts are responsible for 5% to 20% of blindness in children worldwide and for an even higher percentage of childhood visual impairment in developing countries.

The prevalence of childhood cataract varies from 1.2 to 6.0 cases per 10,000 infants.

Cataracts in children not only blur the retinal image but also disrupt the development of the immature visual pathways in the central nervous system.

Hence timely removal of cataract followed by prompt visual rehabilitation is of utmost importance in children.

History..

Careful history including a family history fromthe parents.

• Ask about any illnesses or drugs used during thePregnancy

• Find out if the child is developing normally

• Child should be examined by a paediatrician,to look for other congenital anomalies

Ocular examinationVisual acuity

Preverbal child:Fixation behavior A baby can hold fixation on a target & follow it

around in the space as the target moves,in a normally illuminated room- ‘fix&follow’

CSM method: central, steady, and maintained fixation on a target. If each eye fixates centrally rather than eccentrically, holds steady fixation on that target rather than searching for it or wandering, and continues to stay fixated on that target even when occlusion is removed from the fellow eye, the vision is noted "CSM".

Preferential looking- Teller’s acuity cards uniocularly &

binocularly

Optokinetic nystagmus: It is a rapid screening method for gross integrity

of visual pathway. Optokinetic response is generated with the use

of moving field stimulus which induces pursuit movement.

OKN is an involuntary pursuit response to moving stripes.

A child with some vision will demonstrate a nystagmus as the stripes moves across the field of veiw.(catford drum)

Visual evoked potential:It measures EEG pattern created by visual

stimuli.

Electrodes are placed on the occipital region & visual stimuli-bright flash square wave/phase alternating checker boards,shown to child.

Response is compared with age matched controls.

Verbal Child -preschool(2-5yr)2yr old child can easily match simple forms

& responds well to learning through demonstration.

Visual acuity testing – matching task.

The child has to find out the matching block or point to the shape that matches the target kept at a distance of 3meters.

Lea symbol charts HOTV test Landolt C rings Tumbling E Cardiff acuity test

>5yrs : Snellen visual acuity charts.

Slit lamp biomicroscopy

Density, size,morphology &location of cataract.

Associated anomaly: Aniridia Microcornea Coloboma Persistent pupillary membrane.

Dilated fundus examination & USG-Bscan

Biometry & IOL power calculation At birth axial length of globe is 16 mm and

increases to 20 mm on the completion of 2 years. At birth the human lens is more spherical than in

adults.

It has a power of about 30D, decreases to about 20-22D by the age of five i.e. Myopic shift.

This means that an IOL which gives normal vision to an infant will lead to significant myopia in adulthood.

These changes are most rapid during the first few years of life and this makes difficult to predict the correct power of lens for any child.

There is also change in size of capsular bag from 7mm at birth to 9mm at 2 years.

An ideal IOL power should aim at prevention of amblyopia in childhood and least possible residual refractive error in adult.

Undercorrect the IOL power at the time of surgery to prevent significant myopia later.

Keratometry- handheld keratometer A-scan-immersion technique.

Formulas 1.SRK/T : AL > 26mm

2.Holladay II : AL 24-26mm

3.Hoffer Q : AL < 22mm

age undercorrection

Upto 2 yrs 20%

>2 yrs 10%

Lab investigations:

CBC BSL Urine proteins TORCH titres VDRL urine for reducing substances &red cell

galactokinase sr.calcium & phosphate karyotype

Indications of surgery

Visually significant central cataracts Dense nuclear cataracts

Cataract a/w strabismus

Cataract obstructing examiners view of the fundus

Timing of surgery

Bilateral cataract1.Bilateral dense

• Early surgery – before10 wks of age • To prevent simultaneous deprivation amblyopia. • Denser eye should be addressed first

2. Bilateral partial

• Monitor lens opacity and visual function • Intervene latter if vision deteriorates.

Unilateral cataract1. Unilateral dense • urgent surgery with in 6 wks. • Followed by aggressive anti-amblyopia

therapy

2. Unilateral partial • Can be observed or treated non-surgically

with pupillary dilatation and possibly part time contra lateral occlusion to prevent amblyopia.

Pediatric cataract surgery differs from adult:

Small size of eyes Highly elastic anterior capsule Low scleral rigidity Dense vitreous

Propensity for severe post-op inflammation

Constantly changing refractive status Tendency to develop amblyopia

Surgical techniques:

Lensectomy + primary posterior capsulotomy & anterior vitrectomy with/without primary IOL implantation.

Primary IOL implantation in infants – controversial -high tissue reactivity -marked changes in AL & Refractive status. Safe & effective alternative to contact lens/spects.Aids amblyopia treatment by eliminating period of

uncorrected aphakia.

Pars plana Lensectomy- if no IOL implantation is planned. Performed through pars plana incision with

vitreous cutting instrument/manual aspirating device.

Disadvantage- capsular bag is not preserved, so in-the-bag IOL implantation is not possible.

Limbal lensectomy – Most preferred approach especially when

primary or secondary IOL implantation is planned.

If IOL is being implanted-partial thickness scleral incision , 2-2.5 mm from limbus or a clear corneal incision.

Scleral tunnel- preffered- maintains AC & prevents iris prolapse.

2. Management of anterior capsule: Manual continuous curvilinear capsulorhexis using

Uttrata forceps. Anterior capsule in tough & elastic

It is facilated by using highly retentive viscoelastic e.g.Healon GV, force lens posteriorly and reduce its anterior convexity-combat the effect of vitreous upthrust.

Anterior capsule-stained with Trypan blue.

Small CCC – 5mm diameter.

Capsular flap is frequently released to inspect size,shape & direction of the tear.

More pull is needed centripetally to avoid extension of CCC.

2 incision pull-push technique:

2 small incisions superior & inferior Grasp the centre of flap of superior incision & push

towards centre-semicircular tear. Grasp the centre of flap of inferior incision & pull

towards centre-semicircular tear.

Vitrector,Radiofrequency diathermy,Fugo plasma blade.

Manual continuous curvilinear capsulorhexis is gold standard.

3.Lens matter is aspirated by using vitreous cutter or a

Simcoe cannula.

4. Primary IOL is implanted in the bag for long term stability & safety.

children < 2yrs :Downsize IOL to 10mm diameter.To prevent- capsular bag stretching-PC folds.Lens epithelial cells migrate towards the visual

axis through folds-PCO.

Single piece acrylic IOL is best,less capsulorhexis ovaling & capsular bag stretch.

PMMA IOL can be used.

5.Management of Posterior capsule:

Child < 5 yrs Primary Posterior capsulotomy+ anterior vitrectomy to prevent opacification. Manually or vitrector

Children > 5yrs: PC left intact Nd:YAG laser posterior capsulotomy in early

post-op period.

Intraop miotics-avoided-to prevent ant.segment inflammation.

Use of LMW Heparin(5IU in 500ml) irrigating solution reduces ant.segment inflammation.

Low scleral rigidity-wound is not self sealing-fish mouthing. Suture the wound at the end.

Visual rehabilitation

Spectacles Useful for older children with bilateral aphakia In infant inappropriate because of weight, unpleasentappearance, prismatic distortion and constriction of

visual field.

Contact lenses Provide superior optical option for unilateral aphakia Tolerance is reasonable until the age of 2 years CL become dislodged leading to period of visual

deprivation with the risk of amblyopia.

Part time occlusion of better eye in cases of unilateral cataract.

IOL implantation Performed in younger children and even infant. Most effective and safe.

Piggyback IOL in infants-temporary polypseudophakia.

Post.lens-in the bag; ant.lens-ciliary sulcus1-2 yrs after surgery,ant lens is

explanted/exchanged.

Post-op Complications

1. Uveal inflammation: Common complication-increased tissue

reactivity in children in early post-op period.

Uveitis-membrane formation,pigment deposition, Posterior synechia.

topical & systemic steroids.

2.Glaucoma glaucoma occur in the immediate post operative

period is secondary to pupil block or PAS formation esp in small eyes.

Glaucoma may occur after lensectomy, if it is carried out in the first week of life.

This glaucoma is very difficult to treat and frequently leads to blindness.

Delaying surgery until after the child is 3-4 months old makes it unlikely that the eyes will recover 6/6 vision but it reduces the risk of glaucoma

Open angle glaucoma- commonest type Occur about 7 years after surgery. The mechanism of glaucoma is not exactly

understood. decreased incidence of open-angle glaucoma in

pseudophakic eyes compared to aphakic eyes after cataract surgery.

Probably, the IOL acts as a barrier between the vitreous and trabeculum, preventing a vitreous chemical component from acting on the trabeculum.

Vision threatening complication, IOP should be recorded periodically.

Every 3monthly-1st postop yr Twice yearly- 10th yr Once yearly thereafter.

Glaucoma filtering surgery/ drainage implant is often require to control the IOP.

3. Posterior Capsular opacification: Late onset,begins 18months after surgery Nearly universal if posterior capsule retained More significance in younger children because

ofmore amblyogenic effect Opacification of anterior hyaloid face may occurdespite capsulorhexis if the anterior vitreous is left

intact. Nd:YAG laser capsulotomy.

Proliferation of lens epithelial cells with in the remnants ofanterior and posterior capsule and is referred asSoemmerring ring.

4.Secondary membrane.Late onset In the pupillary region Fibrinous post operative uveitis in normal

eye unlessvigorously treated may also result in

membrane formation. Thin membrane opened with Nd:YAG laser Thick ones may require membranectomy.

5.Pupillary capture Commonly seen in children <2yrs,size of

optic less than 6mm, IOL placed in ciliary sulcus.

Left untreated if asymptomatic.

Retinal detachment,CME -less common complications

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