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Strabismus (Squint eyes)
Strabismus refers to a condition of
misalignment of the eyes.
The
misalignment can be present on the
horizontal; vertical or oblique level
Causes
- Infantile squint : these types develop typically
from the third month of life
- Secondary squint :
This is a deviation which develops
due to a disease affecting the
vision in an eye.
-
Accommodative squint : this type
develops due to a focal problem
-
Neurological squint : this develops
from a neurological paralysis of an
eye muscle
Evaluation
In the evaluation of strabismus all the
factors that can cause the condition
will be considered carefully by the
ophthalmologist as each cause might have
a different implication and lead to
different approaches and management.
Symptoms and presentation
Small children will usually present with
the observation of the presence of a
squint by the parents or the doctor.
Older children and adults will possibly
experience double vision when a squint
develops.
Early
management:
It is of extreme
importance that strabismus must be
examined and managed as early as
possible. Firstly the cause must be
determined. Secondly many types of
strabismus can develop a weak eye (
amblyopia) This problem is mostly
reversible if detected early. If
detected too late it becomes
irreversible. Thirdly, the earlier the
alignment and amblyopia can be corrected
the better the long term visual outcome.
Types
The two
most common types are
1)
Inwards deviation ( Esotropia)
Esotropia can be
a) Infantile type
which usually arises from about the 3`d
month of age.
These eyes usually do
not have a focal problem and have to be
operated to correct the squint and
preferably earlier than later
b)
Accommodative type which usually arises
a bit later from about a year age. These
eyes have a farsighted focal problem and
have to be corrected with the
appropriate spectacles. Surgery is
uncommonly indicated in this type.
2) Outwards deviation (
Exotropia)
Exotropia tends
to present a bit later from about a year
and later. (If it presents earlier it
might have a different approach.)
Exotropia is usually of an intermittent
nature ( sometimes straight and
sometimes deviated) We can distinguish
different behaviour patterns based on
measurement at different distances .
According to these measured deviations
the appropriate management can be
determined e.g. initial observation; eye
exercises or muscle surgery
Treatment
Each type
of strabismus has its individual
appropriate treatment.
The aims are
to obtain and maintain:
1) Normal
vision in both eyes. If amblyopia is an
issue in a specific type, it will be
managed with eye occlusion (patching) or
penalization (dilating the pupil with
eye drops)
2) Correcting
the alignment to as straight as possible
with glasses; prism glasses; surgery;
botulinum toxin injection or exercises.
These treatments are not applied
randomly as one prefers, but are applied
according to strict indications for a
particular type of squint.
3)
Depth perception. Depth perception is
not a quality that all types of
strabismus can attain, but one
endeavours to obtain at least the best
quality that each type allows.
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