infantile cataract

Question 1

define aphakia

Answer 1

the state of having no lense

Question 2

what is Pseudophakia

Answer 2

the state of having an intraocular lens in situ

Question 3

when may aphakia and Pseudophakia be observed

Answer 3

these conditions may be observed following surgery

• infantile cataract

traumatic cataract

senile cataract

and this can be bilateral/unilateral

Question 4

what is the prevelance of infantile cataract

Answer 4

1.9-4.2 per 10,000 live birth in the western world

7.4 per 10, 000 live birth in Asia

Question 5

what is the most common cause of treatable blindness in childreen

Answer 5

bilateral infantile cataract is the most common cause of treatable blindness

accounts for 5-20% of blindness in children worldwide

Question 6

does cataract have an hereditary element

Answer 6

22% of cataract in childhood is inherited

mutation screening identified 200 locus and more than 100 causative genes

Question 7

what is the ateiology of bilateral infantile cataract

Answer 7

idiopathic - most cases

hereditary without systemic disease - approximately 1/3 od cases (autosomal dominant , autosomal recessive or x linked

majority being inherited In an autosomal dominant pattern

metabolic disorders are rare (galactosemia and hypocalcemia) ,

bilateral infantile cataract combined with systemic abnormalities there are many inherited disorders including trisomy 21 , turners syndrome , carniofacial or skeletal deformities , myopathies , neurological disturbances , many of these children have associated mental retardation

intrauterine infections , rubella , toxoplasmosis , cytomegalovirus virus , herpes infections , varicella , syphillis

Question 8

what are the aetiologies for unilateral infantile cataract

Answer 8

idiopathic- most cases

heriditary and or systemic diseases are rare causes

lentconus/ lentiglobyus and persistent feral vasculature (pfv) may be noted in some

associated ocular disease

micropthalmua , anterior segment dysgrensis , persistent foetal vasculature

heriditary and or systemic disease e

rare ateiology

very low birth weight less than 1500 gram is associated with unilateral cataract

other causes of cataract in childhood include

trauma

juvenile ocular inflammatory diseases

uveitis

Question 9

what are the different types of cataract

Answer 9

different types of cataract

nuclear

cortical

lamellar

anterior polar cataract

anterior subcapsualr cataract

sutural cataract

posterior cataract

posterior letinconus/lentiglobus

traumatic cataract

Question 10

what is the most common type of cataract

Answer 10

nuclear 54% is the most common type followed by cortical 25% these two are also associated with posterior capsular opacities

Question 11

what associated ocular conditions are commonly seen with infantile cataract

Answer 11

associated ocular conditions commonly seen with infantile cataract

• persistent fetal vasculature- PFV- developmental abnormality of the primary virtuous and hyaloid vascular system

risk of developing glaucoma - early surgery indicated

anterior segment dysgensis

anriidia

iris colomboma

lens coloboma

Question 12

what is the management of infantile cataract

Answer 12

early adequate and aggressive therapy allows for the best visual outcome

multidisciplanry approach

early referral

detailed pre-op investigation

early surgery

mulitdisciplanry post- op care

delivery of care - argued designated centres provide a higher concentrated level of speciality care

Question 13

what presenting signs and symptoms may someone with infantile cataract present with

Answer 13

leukocoria

poor vision/poor visual behaviour

nystagmus

strabismus

micropthalmos

Question 13

who is involved in the multidisciplinary pre- op investigation

Answer 13

pads - general development of child

signs of metabolic disease or other conditions

any dysmorphic features

ophthalmologist - to check for a red reflex

unilateral or bilateral cataract

density and position of cataract

associated ocular conditions

Examination under aneesthesiia

normal iop in infants is 10 mmhm

geneticist - for genetic counselling

Question 14

how are optometrist and vision scientists involved in the pre- op investigation

Answer 14

Optometrist
Refractive error
Microphthalmos high hypermetropia

Vision Scientist
Pattern / flash VEP’s
Can detect inter-ocular acuity differences
Disadvantages
Expensive
Time consuming
Not widely available

Question 15

what is the role of orthoptist pre - operatively

Answer 15

Detailed case history

Ask parents regarding visual behaviour
Visual assessment
Response to light switched on / off

Ability to fixate & follow in all positions of gaze
Fixation patterns (steady / unsteady)

FCPL cards
Presence of deviation
Esotropia / exotropia
Common in unilateral cases

CT: maybe only possible by CR’s only
Presence of nystagmus
Rowing eye movements

Large amplitude, low frequency & pendular waveform typical
Presence of BSV
Relate to age (usually infants <3/12 old)
Measure deviation
PRT / Hirshberg / Krimsky

Question 16

what information needs to be relayed to parents

Answer 16

Bilateral cataract bilateral stimulus deprivation i.e. surgery essential

Unilateral cataract: parents choice whether to treat

Must inform parents therapy involves
Surgery

Potential post-op complications
Possible need for further surgery
Occlusion until 7 yrs of age

Optical correction for life

Frequent hospital visits especially for 1st 7 yrs of life

Question 17

when should active management be discarded

Answer 17

Poor GH - systemic disease

Severe other ocular disease

ROP

Toxoplasmosis

Absent flash VEP

Parents refuse post-op occlusion/ child and/or parents are unlikely to manage post-op occlusion

Marked microphthalmos

Severe PFV (persistent fetal vasculature)

Mental retardation  non-compliance with post-op therapy

Question 18

what are options for surgery

Answer 18

Options
Remove lens (lensectomy)  APHAKIC

Remove lens + IOL implant 
PSEUDOPHAKIC

Posterior capsulotomy with anterior vitrectomy and IOL implant is the surgery of choice in pediatric patients

Question 19

when is surgery indicated in older children

Answer 19

if partial cataract which does not greatly impede on visual axis , orthoptist and ophthalmologist may closely observe only

frequently seen in lamellar cataracts

Question 19

when is surgery indicated in infants

Answer 19

surgery for dense infantile cataract is reccommded as early as possible

ideally within the first 6-8 weeks of life

Question 20

what surgical techniques are used for cataracts

Answer 20

Lensectomy + use of aphakic contact lenses has been the ‘gold standard’ method of managing infantile cataract

Small incision lens extraction, anterior vitrectomy & posterior chamber IOL implant
Preferred method in paediatric patients
IOL in infants (<1 years of age) is controversial
Some infants are left aphakic

Bilateral infantile cataracts
Surgery on BE at the same time / within 1 week to avoid amblyopia

Question 21

what are the advantages of having g an intrauouclar lens implant and disadvantages

Answer 21

• no difference in image size/ optical abberations

overcome handling/wearing problems associated with contact lenses

disadvantages

require near refraction

intracoular power lens calculation difficult due to large myopic shift especially first 12-18 months of life

posterior capsular opacification very common

Question 22

what is the intaocular lens power caculation surgery technique

Answer 22

Aim: insert IOL that will render patient emmetropic

No universally accepted paediatric formulae

Under-correction of the emmetropic IOL
calculation advocated
Literature suggest ~6-10D under-correction in infants to allow for myopic shift
IOL power usually range between +24-29 D in infants

Question 23

what proportion of adults and children will be left aphakik

Answer 23

only a small proportion of adults and older children will be left aphakik post op

Question 24

which patients may be unsuitable for intrauouclar lens implants and left aphakik post op

Answer 24

patients that may be suitable for iol implant and left aphakik post op include

Traumatic cataract
Glaucoma
High myopia
Severe uveitis
Previous retinal detachment
Corneal opacities
Aphakia in fellow eye
Complications during cataract surgery
vitreous loss with/without loss of capsular bag, choroidal bleeding &/or anterior chamber loss

Question 25

what are post surgery complications that can occur

Answer 25

post capsular opacification

treated with yag laser capsuolotomy

Pupil decentration /
pupil capture

Iris damage

Retinal detachment

Post-op inflammation – endophthalmitis

Question 26

what is the most sight threatening glaucoma complication and what are the risk factors

Answer 26

2° glaucoma/aphakic glaucoma

Common complication & most sight threatening

Most develop later onset ‘chronic’ OAG
Onset varies from months to decades

Risk factors
Surgery <2 months old
Microcornea
Nuclear cataract
PFV
Retained lens material & need for 2° surgery
Acute glaucoma
Excessive inflammation pupillary block & iris bombe

Question 27

what complications occur only after having intraoucalr implants

Answer 27

Posterior capsular opacification

IOL decentration

Shrinkage of capsular bag

Question 28

how are patients managed post operatively

Answer 28

immediate post op

topical treatment to avoid post open inflammation and synchenia formation

optical correction of aphakia - essential to limit severity of amblyopia and allow development of bincularity

options - contact lens

spectacles are unnaceptbale in unilateral cataract , due to anieskonia , peripheral image distortion and weight imbalance

fit contact lenses in theatre or within 1st few days post op

Question 29

define anisekonia

Answer 29

Aniseikonia is the difference in image size perceived between the eyes from unequal magnification.

Question 30

how are aphakic eyes optically corrected

Answer 30

Lens power
Usually b/w +20 to +35D
Aim to overcorrect by
~3D (<1 year)
~2D (1-2 years)
~1D (>2 years)
Aged ~3 years child given reading glasses / bifocals
Glasses must be prescribed for use when CL’s are not in place

Question 31

how are Pseudophakic eyes corrected

Answer 31

May give optical over-correction (1.5-3D) immediate post-op to provide clear near vision
Aged 2-3 years require near Rx (usually bifocal)

Question 32

how old does a child have to be remove contact lenses

Answer 32

Children >6 years of age can successfully care for, insert and remove their own CL’s provided they receive a step-by-step training scheme using child friendly language (Dewsbery, 2004)

Question 33

what are the disadvantages of contact lense wear for post op management

Answer 33

Problems
Non-compliance
Frequent loss
Frequent CL-checks and change of CL
Rapid change of refractive error in young children
Potential side-effects
‘Red eye’
Keratitis
hypoxic corneal ulceration
corneal vascularisation

Question 34

what are the advantages of contact lense wear as an option for post op management

Answer 34

Advantages
Well tolerated by most (>90%)
Pt’s prefer CL over aphakic glasses
Severe side-effects uncommon

Question 35

when is intraocular lens surgery indicated

Answer 35

Controversial < 1 year
Infant Aphakia Treatment Study Group (2014)

Examined unilateral cataract cases who had surgery < 6 months.

Follow up until 5 years.
Similar outcomes:
Visual acuity and prevalence of strabismus

IOL implant group had more adverse events and/or required additional surgery

Conclusion: IOL implant surgery reserved for those unable to cope with CL wear

Question 36

what type of amblyopia do pts with infantile cataract have

Answer 36

Stimulus deprivation amblyopia is more severe & less reversible than

strabismic/anisometropic amblyopia
The reversibility of amblyopia depends on:
Stage of maturity of the visual system at which the abnormal experience began

Duration of stimulus deprivation
Age at which therapy was initiated

Question 37

what is the main goal of orthoptic management

Answer 37

Amblyopia therapy
Most critical period for visual development

Thought stimulus deprivation before the age of 2-3 months may
severe & permanent visual loss & development of nystagmus
If visual deprivation occurs after 2-3 months
Amblyopia is reversible to some extent

Question 38

what does the visual outcome of amblyopia therapy depend on

Answer 38

Visual outcome depends on:
Age of onset
Unilateral versus bilateral cataract
Other ocular abnormalities/ diseases
Timing of surgery
Post-operative complications
Outcome of amblyopia therapy

Several studies suggest that better visual outcomes are attained when surgery is performed before 6-8 weeks of age
No difference in visual acuity at 1 ye

Question 39

how is amblyopia therapy initiated in unilateral cataracts

Answer 39

Unilateral cataracts
Start occlusion as soon as media is clear & optically corrected
Often needs to be intensive
Maintenance occlusion required until 6-7 years of age!

Compliant pt’s who had early Sx might stop occlusion earlier
Occlusion regime is controversial
Some advocate 25% to 50% of patching of waking hours, others 80%

Question 39

how is amblyopia therapy initiated in bilateral cataracts

Answer 39

Alternating occlusion
Occlusion if 1 eye more amblyopic

Question 40

how is the presence of nystagmus treated

Answer 40

Presence of nystagmus
Optical penalisation (+3.00DS)

Optical penalization is a treatment for nystagmus that involves using corrective lenses to blur the vision in one eye. This can help to reduce the severity of nystagmus and improve visual function.

The presence of nystagmus can be treated with optical penalization of +3.00DS in the following ways:

Full-time optical penalization: This involves wearing the corrective lenses all the time, including when reading and watching television. This can be the most effective treatment for nystagmus, but it can also be the most challenging to adjust to.

Question 41

how long is occlusion therapy done in these patients

Answer 41

Occlusion therapy until 7 yrs old!
Achieving long-term compliance
Problem as child gets older & having maintenance occlusion
Compliance rates reported varies 35%-100%
Leaflets:  parents understanding
Diary
Frequent monitoring & encouragement
Infantile cataract family help groups
Optical penalisation - opaque CL / +3.00DS
Main factors of achieving optimum VA:
Compliance with optical correction and amblyopia therapy

Question 42

how strabismus associated with infantile cataracts post operativley- is it higher in unilateral or bilateral cases

Answer 42

Surgery is recommended to be performed before 6-8 weeks to get maximum visual outcome. The same is the case to minimise motor outcomes such as strabismus and nystagmus

The frequency of strabismus is higher in unilateral cataracts (50-90%) compared to bilateral cataracts (40-60%). The prevalence of strabismus may be largely related to the position of the opacity and duration and density of form deprivation. Those with minor opacities such as lamellar, sutural, sectorial and polar cataracts are less likely to develop strabismus (Forster et al. 2004).

Question 43

what Is the prevalence of strabismus in different groups of treatment for infantile cataract

Answer 43

The Infant Aphakia Treatment Study (IATS) is a multicenter, randomised controlled clinical trial study in the USA comprising of 114 infants
Timing of surgery 2 strata groups:28-48 days (<6 weeks) vs 49-210 days (>6 weeks to 7 months)
Prevalence of strabismus pre-op and post-op same in IOL and aphakia group
Prevalence of strabismus pre-op: 25%
43% esotropia and 57% exotropia

Early Sx: 6% had strabismus pre-op
Late Sx: 39% had
strabismus pre-op
Concluded strabismus is more likely to develop in infants who undergo surgery after 6 weeks of age (critical period for development of BSV! Birch et al )

Question 44

what is the likelihood of developing bsv post op

Answer 44

Bilateral cataract more likely to demonstrate BSV than unilateral cataract pt’s.
Commonly, only gross stereopsis present
Early surgery higher chance of binocularity with stereoacuities of 50-310’’(Lloyd et al. 1995)
Better binocular functions may be observed with IOL implant than aphakic CL correction (de Decker et al. 1993)

Question 45

describe the association between nystagmus development and the treatment of infantile cataract

Answer 45

Nystagmus may be present before the cataract surgery, and frequently presents as roving eye movements. However nystagmus may first develop after the surgery. A higher proportion of bilateral cataract cases develop nystagmus. The later the surgery is performed (later than 2-3 months) the more likely nystagmus will develop.

Some believe the presence of manifest nystagmus indicates poor visual prognosis after cataract surgery while others suggest that good outcome can be achieved, at least in some patients (Rabiah et al. 2002).
The majority of children experiencing profound form deprivation as a result of dense opacities such as nuclear, posterior lenticonus, PHPV and posterior polar cataracts ultimately exhibit nystagmus. The most common type of nystagmus recorded by eye movement equipment is manifest-latent nystagmus (MLN) (Forster et al. 2004). The critical period for steady fixation and ocular alignment may be less than 3 weeks of life which further support the need for early surgery (Forster et al. 2004). The nystagmus intensity may dampen in some children following cataract surgery (Rabiah et al. 2002)
Some unilateral cataract cases (children and adults) with no perception of light (PL) or PL only may develop nystagmus (usually vertical) in the affected eye only. This is known as the Heiman-Bielschowsky phenomenon

Question 46

what happens if cataract is left untreated

Answer 46

Many opacities do not change with time

A few reabsorb spontaneously
rubella, PFV or particular syndromes

Another few may swell, inducing pupillary block & glaucoma

Small opacities can have relatively minor effect on visual development

Treatment may involve optical correction and occlusion only
Monitor closely