Squint or Strabismus in Children
When the eyes are not looking towards the same direction, this is referred to as a squint. Children with this eye condition usually stop the use of the said eye. If this continues, it can result to visual loss or amblyopia, which could be permanent if left untreated. Usually, amblyopia is treated by covering the good eye with a patch so that the child can be forced to use the affected eye. The treatment can also successfully correct the squint's appearance. Such treatment usually requires surgery.
Squint is actually an eye condition where one of the eyes look straight while the other points up, inwards, outwards or down.
Understanding Eye Muscles
Movement of your eyes is actually under the control of six muscles, which are responsible for pulling your eyes in different directions. For instance, looking to the left will require the lateral rectus muscle pulling your left eye outwards as well as the medical rectus pulling your right eye inwards.
Development of a squint occurs when these six muscles failed to work and balance correctly resulting to the eyes not moving together.
Different Kinds of Squint
A squint can be described and classified according to:
- direction of squinting or turning eye:
- Eye turns inwards = esotropia.
- Eye turns outwards = exotropia.
- Eye turns upwards = hypertropia.
- Eye turns downwards = hypotropia.
- Squint is constant or always present, or intermittent
- If the affected eye only turns when both eyes are being used or open (manifest squint) or if the eye only turns when shut or covered (latent squint)
- If the angle or severity of the squint is observed to be the same in every direction or not:
- Concomitant squint: the angle or degree of the squint is the same in all direction all the time. In short, the two eyes are moving well and all the eye muscles are working properly but out of alignment by the same amount.
- Incomitant squint: the angle or degree of squint varies. For instance, looking to the left shows no observable squint but looking to the right shows a squint.
- Based on age when the condition occurred - most of the squints develop within the first three years after birth. In some cases, it may develop in adults and even older children. Usually, squints of adults and children develop due to different causes.
- Based on the cause.
- In children – cause of the squint is generally not known.
- In adults and some children – squint can be caused by damage to the eye, eye muscles, nerves or brain
Causes and Types of Childhood Squint
One out of 20 children is diagnosed with squint during the first three (3) years of their life. The usual causes are listed below:
Congenital Squints (Unknown Cause)
The child, upon birth, already suffers from squint. Or, the squint develops within the next six months. Cause for congenital squint is not usually known although the eye muscles were found to be unbalanced.
If the affected eye turns inwards, it is referred to as esotropia or infantile esotropia. This particular type is quite common and usually run in families which means a genetic component. There are also cases when children with this type of squint have no family history.
If the affected eye turns outwards, it is referred to as exotropia or congenital exotropia. A less common type of squint, affecting children at birth, results to the eye turning downward or upward.
Squint in Relation to Refractive Errors
When talking about refractive errors, they include:
- short sight or myopia
- long sight or hypermetropia
These are eye conditions that resulted from poor focusing of light rays through the eye lens. If a child suffering from refractive error tries to see clearly, one of the eyes might turn. The type of squint affects children aged two years and above, particularly those with long sight. This squint is characterized by the eye looking inward (esotropia).
In general, majority of children who are affected by this eye condition are usually healthy. In some cases, it could be a symptom of a brain or genetic condition. For instance, children suffering from cerebral palsy, hydrocephalus, Noonan syndrome or other medical condition develop a squint.
Problems Associated with a Squint
Amblyopia – also referred to as lazy eye; a condition wherein the child has poor vision due to the non-use of one of the eyes during early childhood. The resulting vision loss from Amblyopia is not correctible even with the wearing of glasses. But it can be treated as long as the treatment is administered before the child reaches seven (7) years old. If not, the condition will remain permanent.
In order to understand this condition, you should first understand vision development. Newly-born babies can actually see and as they grow, the vision develops continuously to the brain, within the brain and from the eye. Your brain will be responsible for interpreting the signals coming from the eye. Development continues until the child is 7 or 8 years old. After this period, the pathways and the parts of the brain that see will now be fully-formed and can no longer change.
In case the child is not able to normally-use both eyes, there will be a problem with his learned vision. This, of course, results to amblyopia or poor/impaired visual acuity. The condition develops together with other eye conditions. It can be said that amblyopia is the result of a developmental problem in the brain instead of the eyes.
Squint can be due to amblyopia. In most cases, the unaffected eye becomes the dominant eye used for focusing. The turning eye will not be used for focusing and signals coming from this eye will even be ignored. For this reason, the affected eye will fail to develop normal vision and amblyopia sets in.
How Squints Look
Most children with squint become self-conscious and usually suffer from low self –esteem. Thus, squint can be considered a cosmetic issue.
Impaired Binocular Vision
Normal eyes focus and look in the same direction. Signals coming from the two eyes are interpreted by the brain forming a 3-dimensional image. With a squint, there are two different focuses because the eyes are looking at different objects. Although you might think that this results to double vision, the brain of the children with squint will simply ignore the other signal. In effect, the child is only seeing with the good eye. Problems with depth perception naturally arise because of these as well as difficulties with seeing objects in 3-D.
Diagnosis and Assessment of Squint
Early diagnosis is the key to the proper treatment of this eye condition. Regular examinations should be done to determine any problems with the child's eyes. Usually, the eyes are examined during birth and after 6 weeks. Visions are also checked when the child enters pre-school.
In some cases, new born babies were found to have a squint but the condition disappears almost immediately. A squint that persists after three (3) months will become permanent unless treatment is administered at once. So, if you suspect that your child has developed a squint even after undergoing routine eye checks, consult your doctor as soon as possible.
Usually, the child with squint is referred to a specialist, the orthoptist. This eye expert is trained to both manage and assess squint and amblyopia in children. If needed, a referral to an ophthalmologist will be given by the orthoptist.
Treatments for Squint
To treat this eye condition, it will usually involve:
Treatment of amblyopia
Surgery for the correction of the squint and restoration of binocular vision
Wearing of glasses for correcting refractive errors
In order to treat amblyopia, restriction of the use of the unaffected eye will be recommended. The affected eye will then be forced to function. When done during early childhood, overall vision will improve to almost normal levels. In short, development catches up. To accomplish this, a technique called eye patching is usually employed.
How long an eye patch is used will vary from child to child. It usually depends on the child's age and severity of the amblyopia. The use of the eye patch is continued until normal vision is acquired or maximum results have been achieved. The duration of the treatment can be from a couple of weeks to several months. During this time, the affected eye is monitored to ensure that it is being used. Maintenance treatments are given until the child is eight years old, at which time the vision is fixed and mature.
In some cases, special glasses or eye drops are used for blurring the unaffected eye. This can be an alternative to wearing an eye patch. Vision therapy is another option. This involves the child playing games which are visually-demanding resulting to the maximum usage of the affected eye.
Refractive Error Treatment
Glasses are usually prescribed for a child with a squint caused by a refractive error. It will straighten the eye and improve vision.
Surgical operation is recommended fro straightening the eyes and restoring binocular vision. The kind of operation will depend on the severity and kind of squint.
Botulinum toxin is another treatment option since it can stop the muscles cells. At present, it is being used as primary treatment to certain squint types such as the one where the eye turns inwards.
Prognosis for Squint
For amblyopia: it is important that the condition is treated during childhood in order to improve vision quicker. Early treatment will also increase chances of a normal vision. If the treatment is administered when the child is old, vision can be improved but not fully-restored.
For improvement of appearance: surgery is usually done to straighten the eyes. In some cases, two operations are necessary to fully-straighten the eyes. There are also cases when the squint returns years after the successful surgery. If this happens, another operation will be done.
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