Wednesday, December 29, 2010

CONGENITAL AND DEVELOPMENTAL CATARACTS

These occur due to some disturbance in the normal
growth of the lens. When the disturbance occurs
before birth, the child is born with a congenital
cataract. Therefore, in congenital cataract the opacity
is limited to either embryonic or foetal nucleus.
Developmental cataract may occur from infancy to
adolescence. Therefore, such opacities may involve
infantile or adult nucleus, deeper parts of cortex or
capsule. Developmental cataract typically affects the
particular zone which is being formed when this
process is disturbed. The fibres laid down previously
and subsequently are often normally formed and
remain clear. Congenital and developmental opacities
assume most variegated appearance and minute
opacities (without visual disturbance) are very
common in normal population. These are detected
with the beam of slit lamp under full mydriasis.

Etiology
Exact etiology is not known. Some factors which have
been associated with certain types of cataracts are
described below:
I. Heredity. Genetically-determined cataract is due to
an anomaly in the chromosomal pattern of the
individual. About one-third of all congenital cataracts
are hereditary. The mode of inheritance is usually
dominant. Common familial cataracts include:
cataracta pulverulenta, zonular cataract (also occurs
as non-familial), coronary cataract and total soft
cataract (may also occur due to rubella).
II. Maternal factors
1. Malnutrition during pregnancy has been
associated with non-familial zonular cataract.
2. Infections. Maternal infections like rubella are
associated with cataract in 50 percent of cases.
Other maternal infections associated with
congenital cataract include toxoplasmosis and
cytomegalo-inclusion disease.
3. Drugs ingestion. Congenital cataracts have also
been reported in the children of mothers who
have taken certain drugs during pregnancy (e.g.,
thalidomide, corticosteroids).
4. Radiation. Maternal exposure to radiation during
pregnancy may cause congenital cataracts.
III. Foetal or infantile factors
1. Deficient oxygenation (anoxia) owing to placental
haemorrhage.
2. Metabolic disorders of the foetus or infant
such as galactosemia, galactokinase deficiency
and neonatal hypoglycemia.
3. Cataracts associated with other congenital
anomalies e.g., as seen in Lowe's syndrome,
myotonia dystrophica and congenital icthyosis.
4. Birth trauma.
5. Malnutrition in early infancy may also
cause developmental cataract.
IV. Idiopathic. About 50 percent cases are sporadic
and of unknown etiology.
Clinical types
Congenital and developmental cataracts have been
variously classified. A simple morphological
classification of congenital and developmental
cataract is as under :
I. Congenital capsular cataracts
1. Anterior capsular cataract
2. Posterior capsular cataract
II. Polar cataracts
1. Anterior polar cataract
2. Posterior polar cataract
III. Nuclear cataract
IV. Lamellar cataract
V. Sutural and axial cataracts
1. Floriform cataract
2. Coralliform cataract
3. Spear-shaped cataract
4. Anterior axial embryonic cataract
VI. Generalized cataracts
1. Coronary cataract
2. Blue dot cataract
3. Total congenital cataract
4. Congenital membranous cataract
I. Congenital capsular cataracts
1. Anterior capsular cataracts are nonaxial,
stationary and visually insignificant.
2. Posterior capsular cataracts are rare and can be
associated with persistent hyaloid artery remnants.
II. Polar cataracts
1. Anterior polar cataract. It involves the central
part of the anterior capsule and the adjoining
superficial-most cortex. It may arise in the following
ways:
i. Due to delayed development of anterior chamber.
In this case the opacity is congenital usually
bilateral, stationary and visually insignificant.
ii. Due to corneal perforation. Such cataracts may
also be acquired in infantile stage and follow
contact of the lens capsule with the back of
cornea, usually after perforation due to ophthalmia
neonatorum or any other cause.
Morphological types: Anterior polar cataracts may
occur as any of the following morphological patterns:
i. Thickened white plaque in the centre of capsule.
ii. Anterior pyramidal cataract. In it the thickened
capsular opacity is cone-shaped with its apex
towards cornea.
iii. Reduplicated cataract (double cataract).
Sometimes along with thickening of central point
of anterior capsule, lens fibres lying immediately
beneath it also become opaque and are
subsequently separated from the capsule by
laying of transparent fibres in between. The
burried opacity is called ‘imprint’ and the two
together constitute reduplicated cataract.

2. Posterior polar cataract. It is a very common lens
anomaly and consists of a small circular circumscribed
opacity involving the posterior pole.
Associations. Posterior polar cataract may be
associated with :
Persistent hyaloid artery remnants (Mittendorf dot),
Posterior lenticonus, and
Persistent hyperplastic primary vitreous (PHPV).
Types. Posterior polar cataract occurs in two forms:
Stationary form and
Progressive form which progresses after birth.
III. Nuclear cataracts
i. Cataracta centralis pulverulenta (Embryonic
nuclear cataract). It has dominant genetic trait and
occurs due to inhibition of the lens development at a
very early stage and thus, involves the embryonic
nucleus. The condition is bilateral and is characterised
by a small rounded opacity lying exactly in the centre
of the lens. The opacity has a powdery appearance
(pulverulenta) and usually does not affect the vision.
ii. Total nuclear cataract. It usually involves the
embryonic and fetal nucleus and sometimes infantile
nucleus as well. It is characterized by a dense chalky
white central opacity seriously impairing vision. The
opacities are usually bilateral and non progressive.
IV. Lamellar cataract
Lamellar or Zonular cataract refer to the developmental
cataract in which the opacity occupies a discrete zone
in the lens. It is the most common type of congenital
cataract presenting with visual impairment. It
accounts for about 40 percent of the cases.
Etiology. It may be either genetic or environmental
in origin.
Genetic pattern is usually of dominant variety.
Environmental form is associated with deficiency
of vitamin D.
Sometimes maternal rubella infection contracted
between 7th and 8th week of gestation may also
cause lamellar cataract.
Characteristic features. Typically, this cataract occurs
in a zone of foetal nucleus surrounding the embryonic
nucleus (Fig. 8.5).
Occasionally two such rings of opacity are seen.
The main mass of the lens internal and external
to the zone of cataract is clear, except for small
linear opacities like spokes of a wheel (riders)
which may be seen towards the equator.
It is usually bilateral and frequently causes severe
visual defects.
V. Sutural and axial cataracts
Sutural cataracts are comparatively of common
occurrence and consist of a series of punctate
opacities scattered around the anterior and posterior
Y-sutures. Such cataracts are usually static, bilateral
and do not have much effect on the vision. The
individual opacities vary in size and shape and have
different patterns and thus are named accordingly as
under:
1. Floriform cataract. Here the opacities are
arranged like the petals of a flower.
2. Coralliform cataract. Here the opacities are
arranged in the form of a coral.

3. Spear-shaped cataract. The lenticular opacities
are in the form of scattered heaps of shining
crystalline needles.
4. Anterior axial embryonic cataract occurs as fine
dots near the anterior Y-suture.
VI. Generalized cataracts
1. Coronary cataract (Fig. 8.6). It is an extremely
common form of developmental cataract occurring
about puberty; thus involving either the adolescent
nucleus or deeper layer of the cortex. The opacities
are often many hundreds in number and have a regular
radial distribution in the periphery of lens (corona of
club-shaped opacities) encircling the central axis.
Since the opacities are situated peripherally, vision is
usually unaffected. Sometimes the associated large
punctate opacities may marginally reduce the vision.
2. Blue dot cataract. It is also called cataractapunctata-
caerulea. It usually forms in the first two
decades of life. The characteristic punctate opacities
are in the form of rounded bluish dots situated in the
peripheral part of adolescent nucleus and deeper layer
of the cortex. Opacities are usually stationary and do
not affect vision. However, large punctate opacities
associated with coronary cataract may marginally
reduce the vision.
3. Total congenital cataract. It is a common variety
and may be unilateral or bilateral (Fig. 8.7). In many
cases there may be hereditary character. Its other
important cause is maternal rubella, occurring during
the first trimester of pregnancy. Typically, the child is
born with a dense white nuclear cataract. It is a
progressive type of cataract. The lens matter may
remain soft or may even liquefy (congenital
Morgagnian cataract).
Congenital rubella cataract may occur alone or as
part of the classical rubella syndrome which consists
of:
i. Ocular defects (congenital cataract, salt and
pepper retinopathy and microphthalmos).
ii. Ear defects (deafness due to destruction of organ
of Corti).
iii. Heart defects (patent ductus arteriosus, pulmonary
stenosis and ventricular septal defects).
4. Congenital membranous cataract. Sometimes
there may occur total or partial absorption of
congenital cataract, leaving behind thin membranous
cataract. Rarely there is complete disappearance of
all the lens fibres and only a fine transparent lens
capsule remains behind. Such a patient may be

misdiagnosed as having congenital aphakia. This is
associated with Hallermann-Streiff-Francois
Synodrome.
Differential diagnosis
Congenital cataracts presenting with leukocoria
need to be differentiated from various other conditions
presenting with leukocoria such as retinoblastoma,
retinopathy of prematurity, persistent hyperplastic
primary vitreous (PHPV), etc., (also see page 282)
Management of congenital and developmental
cataract
A. Clinico-investigative work up. A detailed clinicoinvestigative
work up is most essential in the
management of paediatric cataract. It should aim at
knowing the prognostic factors and indications and
timing of surgery.
1. Ocular examination should be carried out with
special reference to:
Density and morphology of cataract
Assessment of visual function is difficult in infants
and small children. An idea may be made from the
density and morphology of the cataract by
oblique illumination examination and fundus
examination. Special tests like fixation reflex, forced
choice preferential looking test, visually evoked
potential (VEP), optic-kinetic nystagmus (OKN)
etc. also provide useful information.
Associated ocular defects should be noted (which
include microphthalmos, glaucoma, PHPV, foveal
hypoplasia, optic nerve hypoplasia, and rubella
retinopathy etc.
2. Laboratory investigations should be carried out
to detect following systemic associations in nonhereditary
cataracts:
Intrauterine infections viz. toxoplasmosis, rubella,
cytomegalo virus and herpes virus by TORCH
test.
Galactosemia by urine test, for reducing
substances, red blood cell transferase and
glactokinase levels.
Lowe's syndrome by urine chromatography for
amino acids.
Hyperglycemia by blood sugar.
Hypocalcemia by serum calcium and phosphate
levels and X-ray skull.
B. Prognostic factors which need to be noted are:
Density of cataract,
Unilateral or bilateral cataract,
Time of presentation,
Associated ocular defects, and
Associated systemic defects
C. Indications and timing of paediatric cataract
surgery,
1. Partial cataracts and small central cataracts
which are visually insignificant can safely be
ignored and observed or may need non-surgical
treatment with pupillary dilatation.
2. Bilateral dense cataracts should be removed
early (within 6 weeks of birth) to prevent stimulus
deprivation amblyopia.
3. Unilateral dense cataract should preferably be
removed as early as possible (within days) after
birth. However, it must be born in mind that
visual prognosis in most of the unilateral cases
is very poor even after timely operation because
correction of aphakia and prevention of amblyopia
in infants is an uphill task.
D. Surgical procedures. Childhood cataracts,
(congenital, developmental as well as acquired) can
be dealt with anterior capsulotomy and irrigation
aspiration of the lens matter or lensectomy. Surgical
technique of these procedures is described on page
193.
Note. The needling operation (which was performed
in the past) is now obsolete.
E. Correction of paediatric aphakia. It is still an
unsolved query. Presently common views are as
follows:
Children above the age of 2 years can be
corrected by implantation of posterior chamber
intraocular lens during surgery.
Children below the age of 2 years should
preferably be treated by extended wear contact
lens. Spectacles can be prescribed in bilateral
cases. Later on secondary IOL implantation may
be considered. Present trend is to do primary
implantation at the earliest possible (2-3 months)
specially in unilateral cataract.
Paediatric IOL: size, design and power. The main
concerns regarding the use of IOL in children are the
growth of the eye, IOL power considerations,

increased uveal reaction and long-term safety. Present
recommendation are :
Size of IOL above the age of 2 years may be
standard 12 to 12.75-mm diameter for in the bag
implantation.
Design of IOL recommended is one-piece PMMA
with modified C-shaped haptics (preferably heparin
coated).
Power of IOL. In children between 2-8 years of
age 10% undercorrection from the calculated
biometric power is recommended to counter the
myopic shift. Below 2 years on undercorrection
by 20% is recomended.
F. Correction of amblyopia. It is the central theme
around which management of childhood cataract and
aphakia revolves. In spite of best efforts, it continues
to be the main cause of ultimate low vision in these
children.



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