Ambylopia is also sometimes called a ‘lazy eye’.
It is a condition in which the vision in an eye is poor because
of lack of use of the eye early in childhood.
The visual loss of ambylopia becomes permanent if not treated
before the age of about seven years and then cannot be corrected
with the use of glasses.
In order to understand ambylopia it is helpful to understand
how vision normally develops.
When a baby is born, although it can see, its visual system
is not fully developed. The visual system (eyes and parts
of the brain that interpret vision) continues to develop and
mature until the age of about 7 years. In order to mature
properly, the brain needs signals from the eyes about what
they can see. If for any reason a young child does not use
one or both of its eyes properly, then vision will not be
learnt properly and the child will develop poor vision in
the affected eye, ambylopia. Essentially, ambylopia is a developmental
problem of the brain rather than the eye itself.
Causes of ambylopia
A squint is the commonest common cause of ambylopia. When
a child has a squint, one eye usually turns up, down, inward
or outward. In order to prevent the child from seeing double,
the brain ignores the images from the turning eye. As a result
of this the visual system related to this eye fails to develop
properly and it becomes an amblyopic eye with poor vision.
Other causes of ambylopia
Other common causes of ambylopia include refractive errors
(short or long-sightedness, or astigmatism) or congenital
problems such as congenital cataract.
These are all problems, which if not treated early can cause
visual loss but if treated early and appropriately the visual
loss can be miminalised.
How can ambylopia be treated?
The main treatment for ambylopia is to try and encourage the
lazy eye to work by restricting the use of the good eye. If
this is done early in childhood, the vision can often be brought
up to a near normal level, depending on the particular case.
The common way to do this is with ‘patching’.
Quite literally, a patch is placed over the better eye for
a variable amount of time each day, depending on the severity
of the ambylopia and the age of the child.
Treatment is continued until the vision returns to normal
or until there is no further improvement. This can be several
weeks or several months.