|
Squint
|
Squint
is a misalignment of the two eyes so that both the eyes
are not looking in the same direction. This misalignment
may be constant, being present throughout the day, or it
may appear sometimes and the rest of the time the eyes may
be straight.
It is a common condition among children. It may also occur
in adults.
What causes squint?
The exact cause of squint is not really known. The movement
of each eye is controlled by six muscles. Each of these
muscle acts along with its counterpart in the other eye
to keep both the eyes aligned properly. |
A
loss of coordination between the muscles of the two eyes leads
to misalignment. This
misalignment may be the same in all directions of gaze,
or in some conditions the misalignment may be more in one direction
of gaze, e.g., in squint due to nerve palsy.
Sometimes a refractive error hypermetropia (long sight) may lead
to inward deviation of the eye. Poor vision in an eye because
of some other eye disease like cataract, etc. may also cause the
eye to deviate. Therefore it is important in all the cases of
squint, especially in children, to have a thorough eye checkup
to rule out any other cause of loss of vision.
What is binocular vision?
Under normal circumstances, when both the eyes have good vision
and they are aligned properly, they focus on the same object.
Each of the eyes sends picture of the same object, viewed from
a slightly different angle. These two images reach the brain,
where they are fused to form a single three-dimensional picture
with depth perception. This is known as binocular single vision.
What are the problems with squint?
When the eyes are not aligned properly, each of the eyes is focusing
on a different object and sends signal to the brain. These two
different images reaching the brain lead to confusion and may
have either of the two effects:
A child would ignore the image coming from the deviated eye, and
thus sees only one image. But in the process, he loses the depth
perception. This suppression of the image from the deviating eye
results in poor development of vision in this eye, which is known
as amblyopia.
An adult can not ignore the image from either eye, and therefore
has double vision. This can be very annoying and may interfere
with work.
What
are the symptoms of squint?
In a child, the parents may notice the deviation of eyes. It is
important to remember that the eyes of a newborn are rarely aligned
at birth. Most establish alignment at 3-4 weeks of age. Therefore
squint in any child who is more than one month old must be taken
seriously and should be evaluated by an ophthalmologist.
Adults may notice double vision, or misalignment of the eyes.
How is squint diagnosed?
The squint is diagnosed by the ophthalmologist. He or she would
do a few special tests to confirm the squint, to try and find
out the cause and to quantify the amount of deviation. In some
cases there may be a false appearance of squint due to broad nasal
bridge in a child. An ophthalmologist will be able to differentiate
between a true squint and false squint.
What is the treatment for squint?
The aims of treatment of squint in order of importance are:
First of all, the eyes are checked to see if they have any refractive
error that may be responsible for squint. If there is any significant
refractive error present, it is treated first. In some cases (accommodative
squint) a correction of refractive error is all that may be required
to treat squint.
Next the eyes are checked for presence of amblyopia.
It is important to treat the amblyopia before the surgery for squint.
The parents are explained about the importance of this treatment,
as their cooperation is very crucial for the success of this treatment.
The squint is treated by surgery of either one or both the eyes.
The surgery involves weakening or strengthening of the relevant
muscles to restore the balance and to get a good coordination. In
some cases with double vision, prisms may be added in the glasses
to ease the symptoms.
When should the squint be treated?
In a child, the treatment of squint and any associated amblyopia
should be started as soon as possible. Generally speaking, the younger
the age at which amblyopia is treated; the better is the chance
of recovery of vision. Remember that the child would never grow
out of squint. A delay in treatment may decrease the chances of
getting a good alignment and the vision.
Are glasses necessary?
Yes. Surgery can not replace the need for glasses.
If the child has significant refractive error, glasses are a must.
In some cases wearing glasses may correct squint. In other cases,
wearing glasses help the eyes to see clearly. This clear vision
is very important for the treatment of amblyopia, and also for maintaining
the coordination of eyes, once they have been aligned by surgery.
|