CONGENITAL DEVELOPMENTAL GLAUCOMA

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CONGENITAL   DEVELOPMENTAL GLAUCOMA Powered By Docstoc
					CONGENITAL / DEVELOPMENTAL
GLAUCOMAS
TERMINOLOGY
The congenital glaucomas are a group of diverse
disorders in which abnormal high intraocular pressure
results due to developmental abnormalities of the
angle of anterior chamber obstructing the drainage
of aqueous humour. Sometimes glaucoma may not
occur until several years after birth; therefore, the
term developmental glaucoma is preferred to describe
such disorders.
Types
1. Primary developmental/congenital glaucoma.
2. Developmental glaucoma with associated ocular
anomalies.
PRIMARY DEVELOPMENTAL/CONGENITAL
GLAUCOMA
It refers to abnormally high IOP which results due to
developmental anomaly of the angle of the anterior
chamber, not associated with any other ocular or
systemic anomaly. Depending upon the age of onset
the developmental glaucomas are termed as follows:
1. True congenital glaucoma is labelled when IOP is
raised during intrauterine life and child is born with
ocular enlargement. It occurs in about 40 percent of
cases.
2. Infantile glaucoma is labelled when the disease
manifests prior to the child's third birthday. It occurs
in about 50 percent of cases.
3. Juvenile glaucoma is labelled in the rest 10 percent
of cases who develop pressure rise between 3-16
years of life.
212 Comprehensive OPHTHALMOLOGY
When the disease manifests prior to age of 3 years,
the eyeball enlarges and so the term‘buphthalmos’
(bull-like eyes) is used. As it results due to retention
of aqueous humour (watery solution), the term
‘hydrophthalmos, has also been suggested.
Prevalence and genetic pattern
  Most cases are sporadic. About 10 percent cases
exhibit an autosomal recessive inheritance with
incomplete peneterance.
  Although sex linkage is not common in
inheritance, over 65 percent of the patients are
boys.
  The disease is bilateral in 75 percent cases, though
the involvement may be asymmetric.
  The disease affects only 1 child in 10,000 births.
Pathogenesis
Maldevelopment of trabeculum including the
iridotrabecular junction (trabeculodysgenesis) is
responsible for impaired aqueous outflow resulting
in raised IOP. In primary congenital glaucoma the
trabeculodysgenesis is not associated with any other
major ocular anomalies. Clinically, trabeculodysgenesis
is characterized by absence of the angle
recess with iris having a flat or concave direct
insertion into the surface of trabeculum as follows:
  Flat iris insertion is more common than the
concave iris insertion. In it the iris inserts flatly
and abruptly into the thickened trabeculum either
at or anterior to scleral spur (more often) or
posterior to scleral spur. It is often possible to
visualize a portion of ciliary body and scleral
spur.
  Concave iris insertion is less common. In it the
superficial iris tissue sweeps over the
iridotrabecular junction and the trabeculum and
thus obscures the scleral spur and ciliary body.
Clinical features
1. Photophobia, blepharospasm, lacrimation and
eye rubbing often occur together. These are thought
to be caused by irritation of corneal nerves, which
occurs as a result of the elevated IOP. Photophobia is
usually the initial sign, but is not enough by itself to
arouse suspicion in most cases.
2. Corneal signs. Corneal signs include its oedema,
enlargement and Descemet’s breaks.
i. Corneal oedema. It is frequently the first sign
which arouses suspicion. At first it is epithelial,
but later there is stromal involvement and
permanent opacities may occur.
ii. Corneal enlargement. It occurs along with
enlargement of globe-buphthalmos (Fig. 9.5),
especially when the onset is before the age of 3
years. Normal infant cornea measures 10.5 mm. A
diameter of more than 13 mm confirms
enlargement. Prognosis is usually poor in infants
with corneal diameter of more than 16 mm.
iii. Tears and breaks in Descemet’s membrane
(Haab’s striae). These occur because Descemet’s
membrane is less elastic than the corneal stroma.
Tears are usually peripheral and concentric with
the limbus.
3. Sclera becomes thin and appears blue due to
underlying uveal tissue.
4. Anterior chamber becomes deep.
5. Iris may show iridodonesis and atrophic patches
in late stage.
6. Lens becomes flat due to stretching of zonules and
may even subluxate.
7. Optic disc may show variable cupping and atrophy
especially after third year.
8. IOP is raised which is neither marked nor acute.
9. Axial myopia may occur because of increase in
axial length which may give rise to anisometropic
amblyopia.
Examination (Evaluation)
A complete examination under general anaesthesia
should be performed on each child suspected of
having congenital glaucoma. The examination should
include following:
Fig. 9.5. A child with congenital glaucoma.
GLAUCOMA 213
1. Measurement of IOP with Schiotz or preferably
hand held Perkin’s applanation tonometer since
scleral rigidity is very low in children.
2. Measurement of corneal diameter by callipers.
3. Ophthalmoscopy to evalute optic disc.
4. Gonioscopic examination of angle of anterior
chamber reveals trabeculodysgenesis with either
flat or concave iris insertion as described in
pathogenesis.
Differential diagnosis
It is to be considered for different presenting signs
as follows:
1. Cloudy cornea. In unilateral cases the commonest
cause is trauma with rupture of Descemet’s
membrane (forceps injury). In bilateral cases
causes may be trauma, mucopolysaccharidosis,
interstitial keratitis and corneal endothelial
dystrophy.
2. Large cornea due to buphthalmos should be
differentiated from megalocornea.
3. Lacrimation in an infant is usually considered to
be due to congenital nasolacrimal duct blockage
and thus early diagnosis of congenital glaucoma
may be missed.
4. Photophobia may be due to keratitis or uveitis.
5. Raised IOP in infants may also be associated
with retinoblastoma, retinopathy of prematurity,
persistent primary hyperplastic vitreous, traumatic
glaucoma and secondary congenital glaucoma
seen in rubella, aniridia and Sturge-Weber
syndrome.
Treatment
Treatment of congenital glaucoma is primarily
surgical. However, IOP must be lowered by use of
hyperosmotic agents, acetazolamide and betablockers
till surgery is taken up. Miotics are of no
use in such cases.
Surgical procedures for congenital glaucoma
1. Goniotomy (Fig. 9.6). In this procedure a Barkan's
goniotomy knife is passed through the limbus on the
temporal side. Under gonioscopic control the knife is
passed across the anterior chamber to the nasal part
of the angle. An incision is made in the angle
approximately midway between root of the iris and
Schwalbe's ring through approximately 75°. The knife
Fig. 9.6. Technique of goniotomy : A, showing position of
goniotomy knife in the angle under direct visualization; B,
showing procedure of sweeping the knife in the angle.
is then withdrawn. Although the procedure may have
to be repeated, the eventual success rate is about 85
percent.
2. Trabeculotomy. This is useful when corneal
clouding prevents visualization of the angle or in cases
where goniotomy has failed. In this, canal of Schlemm
is exposed at about 12 O’clock position by a vertical
scleral incision after making a conjunctival flap and
partial thickness scleral flap. The lower prong of
Harm’s trabeculotome is passed along the Schlemm’s
canal on one side and the upper prong is used as a
guide (Fig. 9.7). Then the trabeculotome is rotated so
as to break the inner wall over one quarter of the
canal. This is then repeated on the other side. The
main difficulty in this operation is localization of the
Schlemm's canal.
3. Combined trabeculotomy and trabeculectomy is
now-a-days the preferred surgery with better results.
214 Comprehensive OPHTHALMOLOGY
DEVELOPMENTAL GLAUCOMAS WITH
ASSOCIATED ANOMALIES
A wide variety of systemic and/or ocular anomalies
have an associated raised IOP, usually due to
developmental defects of the anterior chamber angle.
Some of the associations are as follows:
1. Glaucoma associated with iridocorneal
dysgenesis. These include: posterior embryotoxon
characterised by a prominent Schwalbe’s ring
(Axenfeld anomaly), Rieger anomaly, Rieger
syndrome, Peter’s anomaly and combined Rieger
syndrome and Peter’s anomaly.
2. Glaucoma associated with aniridia (50% cases).
3. Glaucoma associated with ectopia lentis
syndromes, which include Marfan’s syndrome,
Weil-Marchesani syndrome and homocystinuria.
4. Glaucoma associated with phakomatosis is seen
in Sturge-Weber syndrome ( 50% cases) and Von
Recklinghausen’s neurofibromatosis (25% cases).
5. Miscellaneous conditions. Lowe’s syndrome
(oculo-cerebro-renal syndrome), naevus of Ota,
nanophthalmos, congenital ectropion uveae,
congenital microcornea and rubella syndrome.

				
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Description: Common Eye Disease