Squint
What is squint (strabismus)?
Squint is the misalignment of the eyes. Both the eyes do not look in
the same direction. This misalignment may be constant, being present
throughout the day, or it may appear sometimes.
It is a common condition among children. It may also occur in adults.
What causes squint?
The exact cause of squint is not 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 sightedness) can 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.
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.
Why is it important to treat squint?
In the patient with squint, each eye is focusing on a different object
and is sending different signals 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 treatments available for squint?
The aims of treatment of squint in order of importance are:
- Preserve or restore vision
- Straighten the eyes
- Restore binocular vision
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.
Are glasses necessary?
Yes. Surgery can not replace the need for glasses. If the child has significant refractive error, glasses are a must.
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