Glaucoma in Infants
Glaucoma rarely affects infants. It is estimated that 1 in 5,000
to 10,000 children under 2 years of age will develop glaucoma.
Glaucoma in children under 2 years of age is called infantile (or
congenital) glaucoma. Prompt recognition and timely treatment will
improve the chance of a good outcome. Infantile glaucoma is the
result of failure of fluid to escape from the anterior chamber of
the eye resulting in increased pressure within the eye. The young
eye responds to this increased pressure differently to an adult
eye.
How would a parent know if a child is suffering from
glaucoma?
In keeping with the rest of an infant the immature eye is floppy
and somewhat elastic. Thus early in life (that is before the second
birthday) raised intraocular pressure will stretch the eye and
actually cause it to increase in size (it expands in all
directions/ rather like a balloon being inflated). Early medical
writers termed this buphthalmos (=ox eye) as this increase in size
of the eye was thought to make the infant's eye look like an ox's
eye.
The stretching of the eye has a number of harmful effects on the
eye. As the eye enlarges the cornea increases in size. One of the
many layers of the cornea, Descemet's membrane, does not have much
give and rather than stretch it will split as the eye enlarges.
This splitting results in the cornea losing some of its clarity and
becoming cloudy. This cloudiness of the cornea is the result of
fluid entering the cornea from the anterior chamber via the splits
in Descemet's membrane and is known as corneal oedema. Corneal
oedema causes discomfort and sensitivity to light and increased
tear production.
Thus the cardinal features of infantile glaucoma that may be
identified by a parent are photophobia (sensitivity to light),
increased tearing with an enlarged and cloudy cornea.
What
happens when glaucoma is suspected in a young child?
The child needs to be assessed by an ophthalmologist. Ideally the
child should be referred to an ophthalmologist with experience in
managing childhood glaucoma. Often an examination under anaesthetic
is required to adequately examine the child and confirm the
diagnosis of glaucoma. The diagnosis is confirmed by the presence
of typical corneal changes (enlargement, clouding and splits in
Descemet's membrane), raised intraocular pressure and optic disc
cupping.
What treatment will be
needed?
Initial treatment may be eye drops or medication by mouth to lower
the pressure in the eye. Over the long-term medications have a
significant risk of complication in young children and compliance
with medical therapy is an even greater problem with young patients
than it is with older ones. Surgery is usually required and has a
very high success rate.
Infantile glaucoma is the result of blockage of aqueous (fluid)
drainage at the trabecular meshwork of the anterior chamber angle.
Operations aim to restore the more normal drainage of aqueous. The
two most common operations are goniotomy and trabeculotomy. Both
involve opening up the tissue in the angle to enable the aqueous to
escape more easily from the eye and thus lower the pressure. All
surgery for infantile glaucoma is done under a general anaesthetic.
It is not uncommon for more than one operation to be needed to
completely control the raised pressure of infantile glaucoma.
In some instances operations more often used with adult glaucoma
such as trabeculectomy or Molteno tubes are used. These procedures
aim to create a controlled leak or "fistula" by which the aqueous
can bypass the trabecular meshwork and escape from the eye. As with
adults anti-inflammatory and antibiotic drops are used post
operatively. When trabeculectomy is performed in children an
antimetabolite such as 5-fluorouacil (5-FU for short) is very often
used as children heal much more rapidly than adults.
Will there be any pain?
Before treatment is started there may be some pain related to
the corneal oedema and the photophobia. Pain after surgery for
infantile glaucoma is usually mild and easily controlled with
paracetamol. Severe pain may indicate a significant problem such a
post-operative infection.
Will there be a
long stay in hospital?
Most glaucoma surgery in infants can be done safely as a day case
without the need for overnight admission. If surgery is required
within the first four to five weeks of life the infant may remain
in overnight for monitoring after the anaesthetic.
What follow up will be
required?
Regular and life long follow up will be required. When the child is
quite young it may be necessary for periodic examinations under
anaesthetic. As well as monitoring for raised intraocular pressure
the follow up will involve monitoring of the development of vision,
determine the need for glasses and when older assess any damage to
peripheral visual field.
Will my child's
vision be impaired?
Severe loss of vision due to infantile glaucoma is fortunately
rare. It is particularly seen if the onset of the glaucoma is at or
before birth. Glasses are commonly required for myopia (short
sightedness). This is due to the overall length of the eyeball
being increased by the raised intraocular pressure. Photophobia may
be a persistent problem if the splits in Descemet's membrane are
severe.
What causes infantile
glaucoma?
The precise cause of primary congenital
glaucoma (PCG) is not known. In
Australia approximately 20% of children with PCG have a mutation in the CYP1B1
gene. If one child in a family has PCG
then the risk for a subsequent child to be affected is ~5% and if there are two
affected children in one family the risk for subsequent children is 25%. Australian data suggests that the risk for a
parent with a diagnosis of PCG of having an affected child is 2%.
Infantile and childhood glaucoma may be
associated with other abnormalities in the eye.
The most common of these is a history of having had cataract surgery as
an infant, this is called “aphakic glaucoma”.
Other eye abnormalities that can be associated with glaucoma are the
anterior segment dysgenesis group of disorders which includes Rieger
syndrome. Glaucoma can occur in
association with other systemic abnormalities such as the Sturge-Weber syndrome
and rubella (German measles) embryopathy. Juvenile arthritis may cause inflammation in
the eye (uveitis) that may be complicated by the development of glaucoma.
What are the chances of another baby of mine developing
glaucoma?
The risk is not zero but it is quite low.
Will
my child's lifestyle need to alter in any way?
Most children with infantile glaucoma lead normal lives. Glasses
may be required for focusing errors or photophobia. The small
number of children with more severe visual impairment will require
some degree of help at school.
What research is being done into the causes and treatment of
infantile glaucoma?
Most research into the causes and treatment of glaucoma is directed
to understanding adult glaucoma. Fortunately many of these advances
can be modified to treat children with glaucoma.