IVF clinics are not all created equal... Treatment of amblyopia A

Clinical update
Treatment of amblyopia
A
Dr Steve Colley,
Ophthalmologist.
Tel 9385 6665.
mblyopia (Greek amblys “dim” ops “eye”) is reduced vision due to abnormal wiring
of the visual cortex as a result of impairment to the visual experience of one or both
eyes. Amblyopia affects 2% of the population. It is readily treatable, if detected early. The
typical pathologies that result in amblyopia include refractive error (blurring), strabismus
(misalignment) and, less frequently, deprivation (cataract, ptosis, vitreous haemorrhage).
The rationale for treatment is to improve
visual function, not only to provide a useful
“spare eye” but also to prevent limiting career
opportunities.
Although it is important to treat amblyopia
as early as possible, some studies suggest
children will respond to treatment even
after the critical first seven years (and some
children even as teenagers).
Strabismic amblyopia
This is the most common type of amblyopia.
The deviating eye most commonly turns
in (esotropia) or out (exotropia), and is
suppressed in order to prevent double vision.
This suppression can become so effective
that the affected eye loses its visual potential.
The diagnosis becomes difficult when the
deviation is small and thus is not obvious.
The cover test is essential in diagnosing this
condition.
Refractive amblyopia
This is the most difficult type of amblyopia
to detect. If the two eyes have significantly
different refractive states, the young child
may rely on the sight of the more focused
eye, causing the other eye to lose its visual
potential. The child will appear to have
normal vision because the better eye is
being used for visual tasks. If both eyes are
out of focus, both may become amblyopic.
Cycloplegic retinoscopy is essential for
diagnosis and to determine the correct
spectacles for treatment.
Deprivation amblyopia
This usually causes the most severe vision
loss. It typically affects children with
unilateral or bilateral congenital cataracts
but also may occur in those with corneal
or vitreous opacity or severe ptosis. The
lack of a red reflex on ophthalmoscopy or
even standard photography should be taken
seriously.
Atropine has shown to be as effective as
patching treatment for moderate amblyopia
and may only require instillation once a
week. Systemic side effects are possible.
Frequent follow-up is suggested as 25% of
patients may experience a reduction of vision
within 12 months of cessation of treatment.
Failure of a child to respond to treatment
may be due to poor compliance but it
should also trigger further examination,
and if no obvious cause is found, then
electrophysiology or neuro-imaging should
be considered.
Treatment
An organic cause for vision loss must be
ruled out, and any obstacle to vision treated
(e.g. cataract). Congenital cataracts must be
removed as soon as possible and aphakic
treatment (contact lens or glasses) instigated.
Significant refractive errors need to be
corrected (particularly anisometropic
hypermetropia – unilateral long-sightedness).
Studies have shown it may take as many
as five months for visual improvement to
maximise with corrective spectacles.
If residual amblyopia persists then
penalisation therapy, in the form of patching
of the ‘good eye’or atropine drops, is
warranted.
It is important to remember that the majority
of treatment is carried out by the parents of
the affected child and that it can be difficult
and time consuming, making compliance a
real issue.
Contemporary randomised trials have shown
that significantly less patching than was
previously advocated, can be just as effective.
In moderate amblyopia (6/12-6/24). two
hours a day is advocated, while with severe
amblyopia (6/30-6/120) six hours per day is
now considered appropriate.
Declaration: Perth Eye Centre Pty Ltd, being
the management company for the Eye Surgery
Foundation, has supported this clinical update
through an independent educational grant to
Medical Forum. Author – no competing interests.
Fact Box
• Amblyopia is the most common form
of monocular vision loss in children (and
young adults).
• Early recognition and prompt treatment
are essential in preventing permanent
vision loss.
• Most treatment is delivered by the child's
parents, and may be arduous for them.
Fortunately, contemporary management
regimes have lessened that burden.
• Relapses are common and failure to
respond may suggest other pathology, so
close follow-up is important.
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