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ot<br />

Sponsored by<br />

Lorraine Cassidy FRCOphth<br />

Paediatric cataract<br />

Cataract in children often interferes with normal visual<br />

development and is a significant cause of visual<br />

handicap. Therefore, it is an important problem to pick<br />

up and treat as early as possible.<br />

ABDO has awarded<br />

this article<br />

2 CET credits (LV).<br />

The College of<br />

Optometrists has<br />

awarded this article 2<br />

CET credits. There are<br />

12 MCQs with a<br />

pass mark of 60%.<br />

Cataract in childhood can be classified as<br />

congenital, infantile and juvenile,<br />

depending on <strong>the</strong> age of onset. Congenital<br />

cataract is present at birth, but may not be<br />

obvious and <strong>the</strong>refore can go unnoticed<br />

until it is observed to have an effect on <strong>the</strong><br />

child’s visual function. Infantile cataract<br />

refers to cataract which develops in <strong>the</strong> first<br />

two years of life, and juvenile cataract has a<br />

later onset (many lens opacities which are<br />

classified as infantile or juvenile are, in<br />

fact, congenital cataracts which were not<br />

picked up at birth).<br />

Childhood cataract can also be classified<br />

according to aetiology, (i.e. traumatic<br />

cataract, autosomal dominant cataract etc),<br />

and morphology (i.e. lamellar cataract,<br />

subcapsular, cortical etc).<br />

The importance of making <strong>the</strong> diagnosis<br />

and rapidly implementing treatment of<br />

cataract in <strong>the</strong> young child cannot be overemphasised,<br />

as it is <strong>the</strong> major preventable<br />

cause of lifelong visual impairment. A<br />

simple examination of <strong>the</strong> red reflex in <strong>the</strong><br />

newborn child allows this all too important<br />

diagnosis to be made (Figure 1).<br />

Aetiology<br />

1. Hereditary cataract<br />

Hereditary cataract is passed from one<br />

generation to <strong>the</strong> next in autosomal<br />

dominant fashion in 75% of cases of<br />

congenital cataract 1 . The affected<br />

individuals are usually perfectly well, and<br />

have no associated systemic illness. Less<br />

commonly, <strong>the</strong> inheritance may be<br />

autosomal recessive 2 .<br />

However, <strong>the</strong>re are a number of rare<br />

hereditary syndromes where <strong>the</strong> affected<br />

individual not only has cataract, but also<br />

has an associated systemic illness, for<br />

example kidney and brain disease in Lowe’s<br />

oculo-cerebro-renal syndrome, which is X-<br />

linked recessive. It is, <strong>the</strong>refore, important<br />

that all children with congenital cataract are<br />

examined by a paediatrician to exclude any<br />

underlying systemic disorder.<br />

2. Metabolic cataract<br />

Congenital, infantile or juvenile lens<br />

opacities may have an underlying metabolic<br />

cause, for example, galactosaemia 3 .<br />

Galactosaemia is a metabolic disorder in<br />

which <strong>the</strong> child’s body cannot metabolise<br />

galactose, a major component of milk and<br />

milk products. The baby will have vomitting<br />

www.optometry.co.uk<br />

Figure 1<br />

Red reflex revealing a posterior subcapsular cataract after X<br />

ray irradation of <strong>the</strong> eye<br />

and diarrhoea, and develops typical ‘oil<br />

droplet’ cataracts which are easily seen by<br />

examining <strong>the</strong> red reflex. These are<br />

reversible, and <strong>the</strong> lens returns to normal on<br />

removing dairy products from <strong>the</strong> diet. If<br />

this condition is not picked up and treated,<br />

it leads to dense cataracts, deafness and<br />

death.<br />

Glucose-6-phosphate dehydrogenase<br />

deficiency is an X- linked disorder and<br />

<strong>the</strong>refore affects mainly males. These babies<br />

present with jaundice and have haemolytic<br />

anaemia, and may also develop infantile<br />

cataract. Infection, acute illness and<br />

ingestion of fava beans will precipitate an<br />

attack of haemolysis (rupture of red blood<br />

cells) in <strong>the</strong>se children. Death may result,<br />

unless <strong>the</strong> condition is diagnosed and<br />

treated with an urgent blood transfusion.<br />

Hypoglycaemia of whatever cause may<br />

give rise to lens opacities in a child 4 . The<br />

majority of babies with hypoglycaemia this<br />

profound will also have convulsions and may<br />

have permanent brain damage.<br />

Hypocalcaemia may result in cataracts 5<br />

(Figure 2), though <strong>the</strong>se are usually<br />

functionally less significant than cataracts<br />

resulting from hypoglycaemia.<br />

Mannosidosis is an autosomal recesively<br />

inherited metabolic disease which can be<br />

associated with infantile cataracts 6 . In this<br />

disorder, <strong>the</strong> deficient enzyme is alpha<br />

mannosidase, and <strong>the</strong>se children also have<br />

corneal clouding and optic atrophy. O<strong>the</strong>r<br />

features include deafness, skeletal dysplasia<br />

and mental retardation which is variable.<br />

3. Traumatic cataract<br />

Trauma is <strong>the</strong> most common cause of<br />

unilateral cataract in children. Traumatic<br />

cataract is usually <strong>the</strong> result of a<br />

penetrating injury, though blunt trauma can<br />

also lead to cataract formation.<br />

Figure 2<br />

Lamellar cataract in a patient with a previous<br />

episode of hypocalcaemia<br />


ot<br />

4. Secondary cataract<br />

The most common type of secondary<br />

cataract seen in <strong>the</strong> paediatric<br />

ophthalmology clinic is as a result of uveitis<br />

seen in conjunction with arthritis (juvenile<br />

chronic arthritis (JCA)). The cataract may be<br />

as a direct result of inflammation within <strong>the</strong><br />

anterior segment, or can also result from<br />

<strong>the</strong> steroids used to treat <strong>the</strong> condition.<br />

Cataracts caused by steroid ingestion are<br />

usually posterior subcapsular. Progression of<br />

<strong>the</strong> cataract will be halted following<br />

cessation of treatment although not<br />

reversible.<br />

Less frequently, cataract may be seen<br />

secondary to an intraocular tumour such as<br />

retinoblastoma. Retinoblastoma is a<br />

malignant tumour of <strong>the</strong> retina and can<br />

spread to <strong>the</strong> brain resulting in death,<br />

thus immediate referral and treatment is<br />

vital.<br />

5. Cataract secondary to maternal<br />

infection during pregnancy<br />

The most common maternal infection to<br />

cause congenital cataract in <strong>the</strong> child is<br />

rubella, more commonly known as German<br />

measles. The cataracts caused by rubella<br />

may be present at birth, or develop several<br />

months later. These children may also have<br />

microphthalmia, glaucoma, retinal<br />

disease, microcephaly, deafness and heart<br />

defects.<br />

O<strong>the</strong>r infectious diseases which may<br />

have affected <strong>the</strong> mo<strong>the</strong>r during pregnancy,<br />

such as toxoplasmosis (picked up from cat’s<br />

faeces), toxocariasis (picked up from dog’s<br />

faeces), and cytomegalovirus (CMV) can also<br />

cause congenital cataracts along with<br />

systemic illness in <strong>the</strong> newborn baby.<br />

6. Iatrogenic cataract<br />

Iatrogenic cataract is most commonly seen<br />

in children who have had total body<br />

irradiation 7 for leukaemia, and in children<br />

who have had organ transplants and are on<br />

long-term systemic steroid <strong>the</strong>rapy 8 . These<br />

children are usually older children and do<br />

very well after cataract surgery.<br />

7. Syndromes and congenital cataract<br />

There are large variety of chromosomal and<br />

dysmorphic syndromes, in which <strong>the</strong> child<br />

will have a high risk of having congenital<br />

cataract (Table 1). It is important to notice<br />

any abnormal features in children presenting<br />

with cataract, such as unusual facial<br />

features, extra digits, unusual skin, short<br />

stature, developmental delay, microcephaly<br />

or hydrocephaly, as it is essential that <strong>the</strong><br />

child’s diagnosis is made so that any<br />

necessary treatment is given to <strong>the</strong> child,<br />

and so <strong>the</strong> parents can receive genetic<br />

counselling about <strong>the</strong> possible risks of<br />

producing o<strong>the</strong>r offspring with similar<br />

problems.<br />

Presentation<br />

How do children with cataracts present?<br />

Obviously, older children are able to tell<br />

<strong>the</strong>ir parents and carers that <strong>the</strong>y are<br />

having visual difficulties. A very shy and<br />

quiet child may not complain, but <strong>the</strong>ir<br />

school-work may deteriorate and an<br />

observant teacher may become suspicious<br />

that <strong>the</strong> child is having visual difficulties.<br />

However, all is not so straightforward<br />

with <strong>the</strong> non-verbal infant or child. These<br />

babies may present in different ways. For<br />

example, <strong>the</strong> mo<strong>the</strong>r or o<strong>the</strong>r family member<br />

may notice leukocoria (a white pupil). The<br />

Table 1 Chromosomal and dysmorphic syndromes associated with congenital cataract<br />







1. Trisomy 21 (Down’s syndrome)<br />

2. Hallermann-Streiff-Francois syndrome<br />

(characterised by certain facial features<br />

such as a thin pointed nose, small<br />

pointed chin, and can be associated<br />

with breathing difficulties and in 15%<br />

mental reardation)<br />

3. Lowe’s oculo-cerebro-renal syndrome<br />

(an X-linked recessive condition<br />

characterised by chubby cheeks, renal<br />

problems, congenital cataract and<br />

glaucoma)<br />

4. Nance-Horan syndrome (an X-linked<br />

condition characterised by abnormal<br />

dentition, prominent ears and congenital<br />

cataract)<br />

5. Smith-Lemli-Opitz syndrome (an<br />

autosomal recessive condition in which<br />

<strong>the</strong> children may have microcephaly,<br />

cleft palate, congenital cataract and<br />

overlapping fingers and toes)<br />

6. Congenital cataract, microphthalmia,<br />

septal heart defect and dysmorphic<br />

facial features<br />



1. Majewski syndrome (nornatal dawrfism,<br />

extra fingers [polydactyly], cleft palate<br />

2. Smith-Lemli-Opitz syndrome (see<br />

above)<br />

3. Schachat and Maumenee’s patient<br />

(1982) - congenital cataract, mental<br />

retardation; obesity; hypogenitalism;<br />

skull deformities; polydactyly<br />

1. Chondrodysplasia punctata (an<br />

autosomal recessive condition<br />

characterised by short limbs, abnormal<br />

skin and typical skeletal features on x-<br />

ray)<br />

2. Autosomal recessive mental retardation,<br />

cataract, ataxia, deafness and<br />

polyneuropathy<br />

3. Cataract, sensoryneural deafness;<br />

hypergonadism; hypertrichosis; short<br />

stature<br />

4. Marinesco-Sjögren’s syndrome (an<br />

autosomal recessive condition<br />

characterised by unsteadiness of gait,<br />

poor co-ordination, short stature and<br />

mental retardation)<br />



1. Conradi’s syndrome/Conradi-<br />

Hunermann syndrome (short limbs, skin<br />

changes [pitted skin] and skeletal<br />

abnormalities)<br />

2. Pollitt syndrome – (mental retardation,<br />

brittle hair, short stature and skin<br />

abnormalities)<br />

3. Menke’s disease (an X-linked condition<br />

characterised by severe mental<br />

retardation, kinky hair, bone and<br />

connective tissue abnormalities)<br />


1. Autosomal cerebro-oculofacial skeletal<br />

syndrome (COFS) (an autosomal<br />

recessive syndrome characterised by<br />

microcephaly, joint contractures, typical<br />

facial features and failure to thrive)<br />

2. Autosomal recessive congenital<br />

infection-like syndrome (characterised<br />

by microcephaly, seizures and<br />

intracranial calcification)<br />

3. Autosomal dominant microcephaly, eye<br />

anomalies (congenital cataract and<br />

coloboma), short stature and mental<br />

retardation<br />

4. Autosomal recessive congenital<br />

cataract, mental retardation, motor,<br />

sensory and autonomic neuropathy<br />

5. Early onset Cockayne syndrome<br />

(thought to be <strong>the</strong> same condition as<br />

COFS)<br />

6. Cri du Chat syndrome (5p deletion)<br />

(microcephaly, mental retardation,<br />

round face and high pitched cry in<br />

infancy)<br />

7. Autosomal recessive cataract,<br />

microcephaly, renal tubular necrosis<br />

and encephalopathy with epilepsy<br />

8. Czeizal-Lowry syndrome (microcephaly,<br />

hip disease and mental retardation)<br />

9. Edwards syndrome (aniridia,<br />

microcephaly, small jaw and<br />

abnormalities of <strong>the</strong> nose)<br />

1. HEC syndrome: hydrocephalus, endocardial fibroelastosis, cataract<br />

2. Lerone; craniosynostsosis<br />

3. Martsolf’s syndrome<br />

4. Hydrocephalus and microphthalmia<br />

28<br />

March 9, 2001 OT<br />


Sponsored by<br />

Module 3 Part 3<br />

differential diagnosis of a leukocoria is<br />

listed in Table 2. Suspicion may be aroused<br />

if a baby startles every time someone picks<br />

him/her up. In many cases, congenital<br />

cataracts are spotted by <strong>the</strong> health visitor<br />

at <strong>the</strong> six-week check.<br />

Assessment<br />

When a child presents with cataract, he/she<br />

must have a full ophthalmic examination.<br />

Visual acuity of each eye must be<br />

checked, as this will be a major factor in<br />

planning <strong>the</strong> management. In <strong>the</strong> verbal<br />

child, <strong>the</strong> Snellen chart, Sheridan–Gardner<br />

Singles and Kay Pictures are used to assess<br />

acuity. In <strong>the</strong> non or pre-verbal child, visual<br />

acuity is assessed using Cardiff Acuity Cards<br />

or Forced Choice Preferential Looking (FPL).<br />

It is important that <strong>the</strong> child’s ability to<br />

fixate a light source or torch is not used as<br />

an indicator of visual acuity, as a child with<br />

total cataracts significantly affecting visual<br />

acuity may fix and follow a light source<br />

normally, despite being blind to non<br />

luminous objects.<br />

Strabismus must be checked for and any<br />

co-existing amblyopia managed with<br />

occclusion <strong>the</strong>rapy.<br />

Slit lamp examination performed (a<br />

hand-held slit lamp is useful for examining<br />

very small children), and <strong>the</strong> laterality and<br />

density of <strong>the</strong> lens opacities assessed.<br />

All children should have <strong>the</strong>ir intraocular<br />

pressure checked in order to outrule coexisting<br />

glaucoma. This is best done using<br />

<strong>the</strong> hand-held air-puff tonometer.<br />

Before dilating <strong>the</strong> pupils, an afferent<br />

pupillary defect is excluded (<strong>the</strong>re may be a<br />

retinal or optic nerve lesion contributing to<br />

visual loss and cataract formation).<br />

Dilated fundoscopy is <strong>the</strong>n performed to<br />

ensure <strong>the</strong> retina and optic nerve is normal.<br />

If <strong>the</strong> cataract is so dense that no fundal<br />

details can be seen, B-scan ultrasonography<br />

can be carried out following referral in order<br />

to exclude a tumour or retinal detachment.<br />

The child <strong>the</strong>n has a full physical<br />

examination by a paediatrician, and has<br />

routine blood tests to test for congenital<br />

infection, galactosaemia, hypocalcaemia and<br />

hypoglycaemia. The urine is also checked for<br />

aminoaciduria which may be present in<br />

children with Lowe’s syndrome.<br />

In specialised centres, a visual evoked<br />

potential (VEP) is performed on very young<br />

babies in whom a visual acuity cannot be<br />

obtained, and in children with very dense<br />

cataracts, and in whom a possible coexisting<br />

visual pathway abnormality is<br />

suspected. The VEP gives <strong>the</strong> clinician<br />

information about <strong>the</strong> visual pathways, from<br />

<strong>the</strong> ganglion cell layer in <strong>the</strong> retina to <strong>the</strong><br />

occipital cortex.<br />

Management of<br />

paediatric cataract<br />

The management of cataract in <strong>the</strong> child<br />

www.optometry.co.uk<br />

Table 2 The differential diagnosis of leukocoria<br />

Retinoblastoma - malignant retinal tumour<br />

Cataract - lens opacity<br />

Toxoplasmosis - infection of retina or optic nerve with toxoplasma<br />

Toxocariasis - infection of retina or optic nerve with toxocara<br />

Retinal dysplasia - hereditary retinal maldevelopment<br />

Coats’ disease - congenital retinal telangiectasis and exudate<br />

Retinopathy of prematurity - retinal disease seen in some neonates born at less than 32<br />

weeks’ gestation<br />

Persistent hyperplastic primary vitreous<br />

Retinal astrocytoma - benign retinal tumour, can be associated with a systemic condition<br />

known as tuberous sclerosis<br />

High myopia with posterior staphyloma<br />

Eales disease - retinal vasculitis with haemorrhages<br />

Familial exudative vitreoretinopathy<br />

Extensive myelinated nerve fibres<br />

depends upon several factors: <strong>the</strong> child’s<br />

age; <strong>the</strong> extent of visual loss; whe<strong>the</strong>r or<br />

not <strong>the</strong>re is an associated illness or coexisting<br />

eye disease; and if <strong>the</strong> cataract<br />

affects one or both eyes.<br />

Surgery<br />

Intraocular lens (IOL) implantation<br />

is becoming an increasingly accepted<br />

procedure in young children and infants.<br />

Awareness of <strong>the</strong> rate of myopic shift which<br />

takes place in <strong>the</strong> developing eye, and <strong>the</strong><br />

use of biometry helps to predict appropriate<br />

IOL powers to try to ensure eventual<br />

emmetropia. However, final refraction is<br />

variable, such that emmetropia in adulthood<br />

cannot be guaranteed, as <strong>the</strong>re are<br />

insufficient long-term studies. Whe<strong>the</strong>r or<br />

not an IOL is inserted will depend on <strong>the</strong><br />

age of <strong>the</strong> child (recently in some centres<br />

IOLs are inserted into <strong>the</strong> eyes of babies as<br />

Table 3 The Great Ormond Street Occlusion Regime for Cataract<br />

Occlusion regime for bilateral cataract<br />

1. 0-1/2 octaves interocular difference<br />

in visual acuity – no occlusion<br />

2. 1-2 octaves interocular difference<br />

in visual acuity – 1-2 hours of<br />

occlusion of <strong>the</strong> better eye<br />

3. More than 2 octaves interocular<br />

difference in visual acuity – 2-4<br />

hours occlusion of <strong>the</strong> better eye<br />

4. If no improvement after stage 3 –<br />

full-time occlusion<br />

NB To be reviewed every 2 weeks<br />

* i.e. a child aged 2 months is patched for 2 hours a day,<br />

a 3 month old child for 3 hours/day etc.<br />

** The difference between each Cardiff Card is one octave<br />

young as four weeks of age), whe<strong>the</strong>r or<br />

not <strong>the</strong>re is any underlying ocular<br />

pathology in which IOL implantation is<br />

contra-indicated. In some instances, for<br />

example, in remote areas in less<br />

industrialised countries where it is unlikely<br />

that <strong>the</strong> child will be able to be brought<br />

back for regular follow-up, IOL implantation<br />

is not advisable.<br />

Bilateral cataracts<br />

Surgery is indicated when <strong>the</strong> cataracts are<br />

interfering with normal visual development.<br />

If <strong>the</strong> vision is good, <strong>the</strong>n surgery is not<br />

indicated, and <strong>the</strong> child has regular checkups.<br />

If <strong>the</strong>re is a significant deterioration<br />

in that child’s acuity at any stage, <strong>the</strong>n<br />

surgery is considered.<br />

If a child has bilateral dense cataracts,<br />

one eye is operated on followed by <strong>the</strong><br />

second eye one to two weeks later. The first<br />

Occlusion regime for unilateral cataract<br />

1. The phakic eye is occluded 1hour/day for<br />

each month of life* until 6 months of age.<br />

After 6 months occlusion depends on<br />

interocular difference (see 2-4 below)<br />

2. 0-1/2 octave interocular difference in visual<br />

acuity – 50% of waking hours<br />

3. 1-2 octaves interocular difference in visual<br />

acuity – 75% of waking hours<br />

4. More than 2 octaves interocular difference<br />

in visual acuity – 100% waking hours<br />

NB To be reviewed every 2 weeks<br />


ot<br />

eye is occluded post-operatively until <strong>the</strong><br />

second eye is operated on, to prevent<br />

amblyopia in <strong>the</strong> un-operated eye. In very<br />

young babies, an IOL is not inserted; <strong>the</strong>se<br />

babies are given contact lenses one to two<br />

weeks post operatively, and if contact lens<br />

are contra-indicated, <strong>the</strong> child is given<br />

aphakic spectacles. In some of <strong>the</strong>se<br />

children, an IOL may be inserted as a<br />

secondary procedure when <strong>the</strong> eye has<br />

grown. In general, an IOL is inserted into <strong>the</strong><br />

eye of older babies, and depending on <strong>the</strong><br />

age of <strong>the</strong> child, an IOL power is selected<br />

(according to <strong>the</strong> biometry) to make that eye<br />

appropriately hypermetropic, and hence allow<br />

for <strong>the</strong> myopic shift which takes place in <strong>the</strong><br />

developing eye; <strong>the</strong> aim is for emmetropia<br />

when <strong>the</strong> eye is fully grown.<br />

In <strong>the</strong> older child, for example a seven<br />

year old child with bilateral cataracts which<br />

are beginning to significantly interfere with<br />

visual acuity, <strong>the</strong> eye with <strong>the</strong> worst visual<br />

acuity is operated on, followed by <strong>the</strong><br />

second eye at least three to four weeks<br />

later.<br />

All surgery has potential complications,<br />

and <strong>the</strong> parents are warned about all<br />

possible complications pre-operatively (see<br />

later). Complications of lens aspiration and<br />

IOL implantation include post-operative<br />

uveitis, endophthalmitis, glaucoma and<br />

retinal detachment. In addition, <strong>the</strong>re is a<br />

greater than 90% risk that <strong>the</strong> posterior<br />

capsule will become thickened within in a<br />

year, which requires a fur<strong>the</strong>r procedure<br />

ei<strong>the</strong>r with laser or surgical capsulotomy to<br />

clear <strong>the</strong> visual axis and restore visual<br />

acuity to what it was initially postoperatively.<br />

In order to reduce <strong>the</strong> need for<br />

repeated general anaes<strong>the</strong>tics in order to<br />

perform laser and or surgery, a primary<br />

posterior capsulorhexis (and limited anterior<br />

vitrectomy) may be performed. This involves<br />

making a hole in <strong>the</strong> posterior capsule and<br />

removing a small amount of vitreous at <strong>the</strong><br />

time of <strong>the</strong> initial cataract surgery. This<br />

procedure significantly reduces <strong>the</strong><br />

development of posterior capsular<br />

opacification.<br />

Unilateral cataract<br />

In infants with unilateral cataract, <strong>the</strong><br />

cataract is most likely to be idiopathic and<br />

<strong>the</strong>re is usually no associated systemic<br />

disease. It is important not to confuse<br />

asymmetric bilateral cataract with unilateral<br />

cataract and, hence, careful slit lamp<br />

examination is essential in all children with<br />

cataract, as <strong>the</strong>re may be very subtle<br />

changes in one lens and dense cataract in<br />

<strong>the</strong> o<strong>the</strong>r.<br />

With regard to <strong>the</strong> management of<br />

unilateral cataract, <strong>the</strong> decision to operate<br />

depends on <strong>the</strong> density of <strong>the</strong> lens opacity,<br />

whe<strong>the</strong>r or not <strong>the</strong>re is any associated<br />

microphthalmos, and on <strong>the</strong> parent’s<br />

motivation to have <strong>the</strong> surgery performed.<br />

The parents need to be fully informed that<br />

surgery alone will not improve <strong>the</strong>ir child’s<br />

vision, and that <strong>the</strong> management of<br />

amblyopia is <strong>the</strong> key to a successful result.<br />

This entails optical correction and many<br />

hours of patching <strong>the</strong> normal eye every day<br />

(Table 3), which as one knows can be<br />

extremely difficult in a small infant or<br />

toddler, and needs to be maintained for<br />

many years. If occlusion is not performed<br />

<strong>the</strong> eye will remain densely amblyopic.<br />

It has been reported extensively in <strong>the</strong><br />

literature that children who have had<br />

surgery for bilateral cataracts have a much<br />

better visual outcome than children who<br />

have had surgery for unilateral cataract.<br />

Children with unilateral cataract need<br />

diligent occlusion <strong>the</strong>rapy of <strong>the</strong> unoperated<br />

eye toge<strong>the</strong>r with accurate optical<br />

correction of <strong>the</strong> operated eye to obtain a<br />

good visual result.<br />

Optical correction<br />

post-operatively<br />

Aphakia<br />

If <strong>the</strong> child has not had an IOL inserted and<br />

is <strong>the</strong>refore aphakic, contact lenses are<br />

fitted as soon as possible after surgery,<br />

regardless of age. This is usually done one<br />

to two weeks post-operatively. The baby is<br />

refracted and contact lenses fitted. Contact<br />

lenses are relatively safe 9 , <strong>the</strong>y can be used<br />

in combination with spectacles for near, and<br />

also to correct aniseikonia 10 . Rigid gas<br />

permeable contact lenses are most suitable<br />

for <strong>the</strong> management of aphakia, as <strong>the</strong>y<br />

have a wide range of powers, can correct<br />

astigmatism, and are relatively cheap. The<br />

disadvantages of contact lens wear are<br />

similar to those seen in adults, and include<br />

hypoxia and infective keratitis. Parents<br />

should be educated about contact lens<br />

hygiene and <strong>the</strong> signs and symptoms of<br />

possible complications associated with<br />

contact lens wear. All infants and<br />

children wearing contact lenses should be<br />

kept under constant review at a specialised<br />

unit.<br />

If contact lenses cannot be fitted (e.g.<br />

raised intraocular pressure, external eye<br />

disease, dry eye, severe microphthalmos or<br />

parents who are unable to cope with<br />

contacts), <strong>the</strong> child is given aphakic<br />

spectacles which have <strong>the</strong> advantage of<br />

increasing magnification and, <strong>the</strong>refore,<br />

enhancing <strong>the</strong> child’s acuity, and in can<br />

make <strong>the</strong> eyes of children with<br />

microphthalmia look slightly bigger.<br />

Pseudophakia<br />

To allow for <strong>the</strong> future growth of <strong>the</strong> infant<br />

eye (i.e <strong>the</strong> myopic shift) an IOL power less<br />

than that to result in emmetropia is used.<br />

This makes <strong>the</strong> child hypermetropic (<strong>the</strong><br />

amount of hypermetropia depends on <strong>the</strong><br />

age of <strong>the</strong> child), <strong>the</strong>n as <strong>the</strong> child’s eye<br />

grows emmetropia is approached. The child<br />

is <strong>the</strong>n given reading spectacles (and a<br />

distance prescription if required).<br />

Amblyopia management<br />

post-operatively<br />

The treatment of amblyopia is essential in<br />

order to obtain a successful outcome in<br />

patients who have had both unilateral and<br />

bilateral cataract surgery. Amblyopia is<br />

managed by giving <strong>the</strong> required optical<br />

correction and occluding <strong>the</strong> eye with better<br />

visual acuity. The occlusion is performed<br />

according to a standardised regime 11<br />

(Table 3). It is important to realise that<br />

excessive patching of <strong>the</strong> phakic eye in<br />

infants with unilateral aphakia may be<br />

associated with increased nystagmus and<br />

can have adverse effects on <strong>the</strong> phakic eye,<br />

hence it is imperative that <strong>the</strong>se children<br />

are reviewed every two weeks.<br />

Complications of<br />

cataract surgery<br />

Cataract surgery in <strong>the</strong> child and especially<br />

in babies has a higher incidence of<br />

complications than those seen after adult<br />

cataract surgery. This may be due to several<br />

reasons: cataract surgery is technically more<br />

difficult in <strong>the</strong> child’s eye, as <strong>the</strong> tissues are<br />

more elastic and behave differently to adult<br />

tissues; <strong>the</strong> child’s eye becomes more<br />

inflammed than an adult eye in response to<br />

an IOL; <strong>the</strong> very young child’s visual system<br />

is still developing and is <strong>the</strong>refore extremely<br />

sensitive to having a defocused image as is<br />

<strong>the</strong> case in aphakia; and a young child is<br />

less likely to fully comprehend <strong>the</strong><br />

importance of keeping dirty fingers away<br />

from <strong>the</strong> operated eye in <strong>the</strong> immediate<br />

post-operative period and, <strong>the</strong>refore, may<br />

rub <strong>the</strong> eye too vigorously resulting in<br />

wound dehisence and iris prolapse or<br />

infection.<br />

There have been many reports of <strong>the</strong><br />

visual outcome and complications of<br />

posterior chamber lens implantation in<br />

children 12-20 . The most common<br />

complications include:<br />

1. Glaucoma<br />

Glaucoma may arise in <strong>the</strong> first few weeks<br />

post-operatively, and may present as a<br />

watery eye with or without photophobia.<br />

The child is usually irritated or just “not his<br />

usual self”. Some children are asymptomatic,<br />

hence <strong>the</strong> importance of regular review with<br />

IOP checks post-operatively.<br />

Glaucoma may also occur as a late<br />

complication years later, and this type of<br />

glaucoma can be asymptomatic, <strong>the</strong>refore all<br />

children who have had cataract surgery<br />

should be followed up for life.<br />

2. Uveitis<br />

All children will develop a certain degree of<br />

uveitis post-cataract surgery. This is kept<br />

30<br />

March 9, 2001 OT<br />


Sponsored by<br />

Module 3 Part 3<br />

under control with frequent installation of<br />

topical steroids, which are given to all<br />

children routinely, and are eventually tailed<br />

off and discontinued. However, some<br />

children (approximately 30%) develop<br />

inflammation with fibrin formation. This<br />

accumulation of fibrin may result in<br />

secondary membrane formation blocking <strong>the</strong><br />

visual axis if not recognised and treated<br />

promptly.<br />

3. Irregular pupil<br />

An irregularly shaped pupil after cataract<br />

surgery may be due to: a) a strand of<br />

vitreous coming forwards from <strong>the</strong> vitreous<br />

cavity to <strong>the</strong> anterior chamber; b) damage<br />

to <strong>the</strong> iris during surgery; and c) iris<br />

prolapse, which may be due to accidental<br />

trauma to <strong>the</strong> eye post-operatively and<br />

requires urgent attention, as if left<br />

untreated that eye may become infected,<br />

and even <strong>the</strong> o<strong>the</strong>r eye may be at a risk<br />

from sympa<strong>the</strong>tic ophthalmia.<br />

4. Endophthalmitis<br />

Bacterial infection of <strong>the</strong> eye is a<br />

devastating complication which can occur in<br />

up to 0.4% of eyes after cataract surgery. It<br />

may occur early (i.e. within days to weeks)<br />

or late (months to years) post-operatively<br />

and presents with a sore painful red eye,<br />

and/or reduced vision, and requires urgent<br />

hospital admission and treatment.<br />

5. Posterior capsule opacification<br />

Posterior capsule opacification occurs in up<br />

to 90% of paediatric eyes after lens<br />

aspiration when <strong>the</strong> posterior capsule and<br />

anterior vitreous face are left intact. These<br />

children, having had a good visual result<br />

initially, later present with blurred vision.<br />

The thickened posterior capsule is seen<br />

using <strong>the</strong> slit lamp, or simply by examining<br />

<strong>the</strong> red reflex. These children are admitted<br />

as a day case and a posterior capsulotomy is<br />

performed. Older children can have laser<br />

treatment without a general anaes<strong>the</strong>tic. In<br />

some cases, <strong>the</strong> capsule thickens again and<br />

may require surgery to clear <strong>the</strong> visual axis.<br />

6. Retinal detachment<br />

Retinal detachment may occur years after<br />

cataract surgery, and present with reduced<br />

vision which may be preceeded by flashes<br />

and floaters.<br />

Conclusion<br />

Cataract in early childhood, if not picked up<br />

early and managed appropriately, can have<br />

devastating visual consequences. Treatment<br />

may not always be surgical, and parents<br />

need to be aware that those children who<br />

do require surgery will also need optical<br />

correction and, in many cases, many hours<br />

of occlusion <strong>the</strong>rapy for <strong>the</strong> treatment of<br />

amblyopia. It is also essential to be aware<br />

that <strong>the</strong>re are many syndromes and systemic<br />

disorders which may be associated with<br />

congential cataract and that may have<br />

implications for <strong>the</strong> child’s health.<br />

Acknowledegemt<br />

Figures 1 and 2 reproduced with kind<br />

permission from Consultant<br />

Ophthalmologist, Nicholas Phelps Brown.<br />

References<br />

1. Scott, M.H., Hejtmancik, J.F.,<br />

Wozencraft, L.A. et al (1994)<br />

“Autosomal dominant congenital<br />

cataract. Intraocular phenotypic<br />

variability”. Ophthalmology 101: 866-71.<br />

2. Forsius, H., Arentz-Grastvedt, B. and<br />

Eriksson, A.W. (1992) “Juvenile cataract<br />

with autosomal recessive inheritance. A<br />

study from <strong>the</strong> Aland Islands, Finland”.<br />

Acta. Ophthalmol. 70: 26-32.<br />

3. Stambolian, D. (1988) “Galactose and<br />

cataract”. Surv. Ophthalmol. 32: 33-49.<br />

4. Merin, S. and Crawford, J. (1971)<br />

“Hypoglycaemia and infantile cataract”.<br />

Arch. Ophthalmol. 86: 495-8.<br />

5. Hochman, H.I. and Mejlszenkier, J.D.<br />

(1977) “Cataracts and pseudotumour<br />

ceribri in an infant with vitamin D<br />

deficiency rickets”. J. Pediatr. 90: 252-4.<br />

6. Letson, R.D. and Desnick, R.J. (1978)<br />

“Punctate lenticular opacities in type II<br />

mannosidosis”. Am. J. Ophthalmol. 85:<br />

218-24.<br />

7. Henk, J.M., Whitelocke, R.A.F.,<br />

Warrington, A.P. et al (1993) “Radiation<br />

dose to <strong>the</strong> lens and cataract<br />

formation”. Int. J. Radiat. Oncol. Biol.<br />

Phys. 25: 815-20.<br />

8. Brocklebank, J.T., Harcourt, R.B.,<br />

Meadow, S.R. (1982) “Corticosteroid<br />

induced cataracts in idiopathic<br />

nephrotic syndrome”. Arch. Dis. Child.<br />

53: 30-4.<br />

9. Amaya, L., Speedwell, L. and Taylor,<br />

D.S.I. (1990) “Contact lenses for infant<br />

aphakia”. Br. J. Ophthalmol. 74: 150-4.<br />

10. Enoch, J.M. and Hamer, R.D. (1983)<br />

“Image size correction of <strong>the</strong> unilateral<br />

aphakic infant”. Ophthalmic Paediatr.<br />

Genet. 2: 153-65.<br />

11. Tayloe, D.S.I., The Doyne Lecture.<br />

(1998) “Congenital cataract: <strong>the</strong><br />

history, <strong>the</strong> nature and <strong>the</strong> practice”.<br />

Eye 12: 9-36.<br />

12. Thouvenin, D., Lesueur, L. and Arne,<br />

J.L. (1995) “Implantation<br />

Intercapsulaire dans les cataractes de<br />

l’Enfant. Etude de 87 cas et<br />

comparaison a 88 cas sans<br />

implantation”. J. Franc. Ophthalmol.<br />

18: 678-687.<br />

13. Knight-Nanan, D., O’Keefe, M. and<br />

Bowell, R. (1994) “Outcome and<br />

complications of intraocular lenses in<br />

children with cataract”. J. Cat. Ref.<br />

Surg. 22: 730-736.<br />

14. Brady, K.M., Atkinson, C.S., Kilty, L.A.<br />

and Hiles, D.A. (1995) “Cataract<br />

surgery and intraocular lens<br />

implantation in children”. Am. J.<br />

Ophthalmol. 120: 1-9.<br />

15. Sinskey, R.M., Stoppel, J.O. and Amin,<br />

P. (1993) “Long-term results of<br />

intraocular lens implantation in<br />

pediatric patients”. J. Cat. Ref. Surg.<br />

19: 405-408.<br />

16. Zwaan, J., Mullaney, P.B., Awad, A., Al-<br />

Mesfer, S. and Wheeler, D.T. (1998)<br />

“Pediatric Intraocular lens<br />

implantation: Surgical results and<br />

complications in more than 300<br />

patients”. Ophthalmology 105: 112-<br />

119.<br />

17. Gimbel, H.V., Basti, S., Ferensowicz, M.<br />

and DeBroff, B.M. (1997) “Results of<br />

bilateral cataract extraction with<br />

posterior chamber intraocular lens<br />

implantation in children”.<br />

Ophthalmology 104: 1737-1743.<br />

18. Crouch, E.R., Pressman, S.H. and<br />

Crouch, E.R. (1995) “Posterior chamber<br />

intraocular lenses: long term results in<br />

pediatric cataract patients”. J. Pediatr.<br />

Ophthalmol. Strabismus 32: 210-218.<br />

19. Burke, J.P., Wilshaw, H.E. and Young,<br />

J.D.H. (1989) “Intraocular lens<br />

implants for uniocular cataracts in<br />

children”. Br. J. Ophthalmol. 73: 860-<br />

865.<br />

20. Churchill, A.J., Noble, B.A., Etchells,<br />

D.E. and George, N.J. (1995) “Factors<br />

affecting visual outcome in children<br />

following uniocular traumatic cataract”.<br />

Eye 9: 285-291.<br />


Lorraine Cassidy is Locum Consultant Ophthalmologist at Great Ormond Street Hospital for<br />

Children, and at St Helliers and Sutton Hospitals, Surrey. She has a special interest in<br />

paediatric ophthalmology and trained with David Taylor and Isabelle Russell-Eggitt at Great<br />

Ormond Street.<br />

www.optometry.co.uk 31

ot<br />

Multiple choice questions<br />

Paediatric cataract MCQs<br />

1. Hypoglycaemia in an infant is most likely<br />

to give rise to all of <strong>the</strong> following except:<br />

a. cataract<br />

b. convulsions<br />

c. permanent brain damage<br />

d. skeletal dysplasia<br />

2. ‘Oil droplet’ cataracts are<br />

associated with which disorder?<br />

a. Galactosaemia<br />

b. Mannosidosis<br />

c. Trauma<br />

d. Glucose-6-phosphate dehydrogenase<br />

deficiency<br />

3. Which one of <strong>the</strong> following statements<br />

is incorrect regarding cataract?<br />

a. Short stature may be associated with<br />

cataract<br />

b. Cataracts which result from <strong>the</strong> metabolic<br />

abnormality known as galactosaemia can be<br />

reversible<br />

c. Congenital cataracts are most easily seen by<br />

looking at <strong>the</strong> red reflex in <strong>the</strong> first week of<br />

life<br />

d. In babies with dense congenital cataract it<br />

is best to wait until <strong>the</strong> child is at least five<br />

years old before considering surgery<br />

4. Which one of <strong>the</strong> following statements is<br />

correct regarding cataract?<br />

a. Contact lenses are contraindicated in<br />

children under six weeks old<br />

b. Leukocoria is always a benign ocular sign<br />

which warrants routine referral<br />

c. Steroid induced cataracts are reversible on<br />

discontinuing steroid <strong>the</strong>rapy<br />

d. Microphthalmos may be a contra-indication<br />

of contact lens wear<br />

Please note <strong>the</strong>re is only ONE correct answer<br />

5. Steroid induced cataracts are typically:<br />

a. lamellar<br />

b. anterior polar<br />

c. cortical<br />

d. posterior subcapsular<br />

6. Which one of <strong>the</strong> following<br />

statements is correct?<br />

a. Children who have had surgery for unilateral<br />

cataract have a much better visual outcome<br />

than children who have had surgery for<br />

bilateral cataracts<br />

b. When a very young infant is having<br />

an IOL implanted, <strong>the</strong> power of <strong>the</strong><br />

IOL is calculated to make <strong>the</strong> child<br />

myopic<br />

c. Management of ambyopia is essential in<br />

improving visual function<br />

d. Bilateral cataracts are often operated in<br />

simultaneously<br />

7. Complications of cataract surgery in <strong>the</strong><br />

child include all of <strong>the</strong> following except:<br />

a. glaucoma<br />

b. uveitis<br />

c. retinal detachment<br />

d. diabetes<br />

8. A child who presents with a watery<br />

eye one or two weeks post cataract<br />

surgery is most likely to have:<br />

a. conjunctivitis<br />

b. a blocked tear duct<br />

c. glaucoma<br />

d. posterior capsular opacification<br />

9. Endophthalmitis occurs in what<br />

proportion of eyes following<br />

cataract removal?<br />

a. 0.4%<br />

b. 1%<br />

c. 0.2%<br />

d. 10%<br />

10. Posterior capsular opacification occurs in<br />

what proportion of eyes following<br />

cataract removal?<br />

a. 50%<br />

b. 60%<br />

c. 70%<br />

d. 90%<br />

11. According to <strong>the</strong> Great Ormond Street<br />

Occlusion Regime for Cataract, a child<br />

with bilateral cataract showing 1-2<br />

octaves interocular difference in visual<br />

acuity will be occluded for what period of<br />

time?<br />

a. One to two hours of <strong>the</strong> better eye<br />

b. No occlusion<br />

c. Two to four hours of <strong>the</strong> better eye<br />

d. Full-time occlusion<br />

12. According to <strong>the</strong> Great Ormond Street<br />

Occlusion regime for cataract, a child<br />

with a unilateral cataract showing more<br />

than 2 octaves interocular difference in<br />

visual acuity will be occluded for what<br />

period of time?<br />

a. 50% of waking hours<br />

b. 1 hour/day for each month of life<br />

c. 75% of waking hours<br />

d. 100% of waking hours<br />

An answer return form is included in this issue.<br />

It should be completed and returned to:<br />

CPD Initiatives (c2983d),<br />

OT, Victoria House, 178–180 Fleet Road, Fleet,<br />

Hampshire, GU13 8DA by April 4, 2001.<br />

32<br />

March 9, 2001 OT<br />


Sponsored by<br />

Module 3 Part 3<br />

Multiple choice answers - The epidemology of cataract<br />

Here are <strong>the</strong> correct answers to CPD module 3 part 2, which appeared in our February 9 issue.<br />

1. The UK government is aiming for how<br />

many cataract operations per year in<br />

its Action on Cataracts initiative?<br />

a. 175,000<br />

b. 250,000<br />

c. 1,500,000<br />

d. 30 million<br />

b is <strong>the</strong> correct answer<br />

The Department of Health, in its initiative<br />

Action on Cataracts, aims to increase<br />

cataract surgery from <strong>the</strong> current annual<br />

estimate of 175,000 cases to 250,000<br />

within three years, mostly by improving<br />

efficiency. There are 1,500,000 cataract<br />

surgeries a year in <strong>the</strong> United States, and<br />

it is estimated that <strong>the</strong>re are 38 million<br />

people blind from cataract in <strong>the</strong> world.<br />

2. Which one of <strong>the</strong> following<br />

statements is correct?<br />

a. Studies investigating cataract are easy to<br />

compare<br />

b. Cataract grading methods should not be<br />

sensitive to change<br />

c. Photographic grading systems are most<br />

reproducible and reliable<br />

d. Lens opacities usually regress in<br />

epidemiological studies<br />

c is <strong>the</strong> correct answer<br />

There have been many different cataract<br />

grading systems used, making comparison<br />

of different studies difficult. In order to<br />

detect change, cataract grading systems<br />

must be sensitive to detect that change,<br />

which is why many systems have been<br />

decimalised from simple 0-5 grading<br />

points, to 0.1, 0.2 etc, up to 5.0.<br />

Photographic systems are most<br />

reproducible and reliable as <strong>the</strong>re is ‘hard<br />

evidence’ to compare, compared to<br />

subjective systems. Lens opacities do not<br />

regress, and so studies with significant<br />

regression suggest that <strong>the</strong> grading of<br />

cataract was not reliable.<br />

3. Which one of <strong>the</strong> following<br />

statements is correct?<br />

a. Genes are important in congenital cataract<br />

b. The genes responsible for age-related<br />

cataract have been identified<br />

c. Environmental factors have been shown to<br />

be more important than genetic make-up<br />

d. Genes are unlikely to be important in agerelated<br />

cataract<br />

a is <strong>the</strong> correct answer<br />

The Twin Eye Study has shown that genes<br />

are important in age-related cataract, with<br />

a heritability of 48%. Environment only<br />

contributed to 14% of <strong>the</strong> variance,<br />

although this may still be important in<br />

individuals with particular genetic defects.<br />

The gene mutations involved in agerelated<br />

cataract are still unknown, but<br />

many mutations have been identified in<br />

congenital cataracts, which are often<br />

familial.<br />

4. The heritability of nuclear cataract<br />

has been reported as:<br />

a. 12%<br />

b. 38%<br />

c. 48%<br />

d. 66%<br />

c is <strong>the</strong> correct answer<br />

The heritability of nuclear cataract in <strong>the</strong><br />

Twin Eye Study was 48%.<br />

5. The prevalence of nuclear cataract:<br />

a. is greater in women than men<br />

b. is greater in men than women<br />

c. is <strong>the</strong> same in <strong>the</strong> two sexes<br />

d. is greatest in <strong>the</strong> 65-74 age group<br />

a is <strong>the</strong> correct answer<br />

The prevalence of nuclear cataract is greater<br />

in women than men, as it is for cortical<br />

cataract. The reasons for this are not<br />

known. The prevalence of cataract is also<br />

strongly age-related, so that cataract is<br />

more common in those aged over 75 than<br />

those aged 65-74 years.<br />

6. In patients over <strong>the</strong> age of 75 years:<br />

a. posterior subcapsular cataract is <strong>the</strong><br />

commonest cataract type<br />

b. cortical cataract is present in over 40%<br />

c. nuclear cataract is rare<br />

d. diabetes is <strong>the</strong> commonest cause of lens<br />

opacities<br />

b is <strong>the</strong> correct answer<br />

Cortical cataract is present in over 40% of<br />

individuals over <strong>the</strong> age of 75 years, and<br />

significant nuclear cataract in at least 50%.<br />

www.optometry.co.uk 33

ot<br />

Multiple choice answers - continued<br />

Posterior subcapsular cataract is least<br />

common, but is still present in over 10% of<br />

those aged over 75. Although diabetes is a<br />

risk factor for <strong>the</strong> development of cataract,<br />

it is only present in around 2% of <strong>the</strong><br />

population and so is not <strong>the</strong> most important<br />

cause of cataract in this age group.<br />

7. Which one of <strong>the</strong> following has NOT<br />

been shown to be associated with<br />

cataract formation?<br />

a. High myopia<br />

b. Marfan’s syndrome<br />

c. Myotonic dystrophy<br />

d. Myas<strong>the</strong>nia gravis<br />

d is <strong>the</strong> correct answer<br />

Cataract has been associated with various<br />

systemic conditions, such as connective<br />

tissue disorders (myotonic dystrophy which<br />

causes ‘Christmas tree’ cataracts) and<br />

Marfan’s syndrome (also associated with lens<br />

dislocation). It is also associated with<br />

intraocular diseases such as uveitis, and<br />

high myopia is a risk factor. Myas<strong>the</strong>nia<br />

gravis, a myopathy causing fatiguable ptosis<br />

and reduced eye movements, is not<br />

associated with cataract itself. (However,<br />

patients may require sustained oral<br />

steroids for its treatment and may<br />

develop cataracts as a result.)<br />

8. Which one of <strong>the</strong> following is<br />

associated with cortical<br />

cataract?<br />

a. Steroid intake<br />

b. Smoking<br />

c. Vitamin D<br />

d. Ultraviolet light<br />

d is <strong>the</strong> correct answer<br />

Cortical cataract is associated with<br />

increasing age, and is more common in<br />

women and people of Afro Caribbean<br />

descent. Ultraviolet light, in <strong>the</strong> form of<br />

sunlight, has been assoiciated with cortical<br />

cataract also. Smoking is not associated<br />

with cortical cataract, and while steroids<br />

may increase <strong>the</strong> risk of all types of<br />

cataract, <strong>the</strong>y are particularly associated<br />

with posterior subcapsular cataract.<br />

9. The London City Eye Study<br />

demonstrated that:<br />

a. alcohol may be related to cataract<br />

b. ultraviolet light exposure is related to<br />

posterior subcapsular cataract<br />

c. smoking is associated with cataract<br />

d. vitamin C is protective in cataract<br />

c is <strong>the</strong> correct answer<br />

The London City Eye Study suggested<br />

smoking was associated with cataract, and<br />

found a greater risk in smokers compared to<br />

ex-smokers, and <strong>the</strong> ex-smokers carried a<br />

greater risk than <strong>the</strong> non-smokers,<br />

suggesting a causal link.<br />

10. Which one of <strong>the</strong> following statements is<br />

incorrect regarding cigarette smoking?<br />

a. It is related to <strong>the</strong> development<br />

of nuclear cataract<br />

b. It is related to <strong>the</strong> development<br />

of posterior subcapsular cataract<br />

c. Ex-smokers have an increased risk of<br />

developing cataract compared<br />

to non-smokers<br />

d. It is related to <strong>the</strong> development<br />

of cortical cataract<br />

d is <strong>the</strong> correct answer<br />

Smoking has been particularly associated<br />

with nuclear cataract, although some<br />

studies have suggested it may also be<br />

associated with posterior subcapsular<br />

cataract. It has not been associated with<br />

cortical cataract, however. As above, <strong>the</strong><br />

London City Eye Study did suggest that exsmokers<br />

carried a greater risk than nonsmokers.<br />

11. Hypertension may be related<br />

to which type of cataract:<br />

a. nuclear<br />

b. cortical<br />

c. posterior subcapsular<br />

d. congenital<br />

c is <strong>the</strong> correct answer<br />

No consistent evidence has linked cataract<br />

to hypertension, although <strong>the</strong> Beaver Dam<br />

Eye Study did suggest that hypertensive<br />

patients were slightly more likely to have<br />

posterior subcapsular cataract than those<br />

without hypertension.<br />

12. Which one of <strong>the</strong> following statements<br />

is correct regarding cataract?<br />

a. 20 million people will be blind due to<br />

cataract by 2020<br />

b. Cataract is more common in men compared<br />

to women<br />

c. Tall height may be associated with cataract<br />

d. Diarrhoea may be associated with cataract<br />

d is <strong>the</strong> correct answer<br />

Case-control studies have suggested that<br />

severe diarrhoeal disease may be associated<br />

with cataract in later life. Low height or<br />

body weight may also be associated<br />

with cataract, and may reflect early<br />

malnutrition.<br />

34<br />

March 9, 2001 OT<br />


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