What is Strabismus?
It is a condition in which the eyes are not properly aligned with each other (they don't look towards an object together). Strabismus can be subtle or obvious, intermittent (occurring occasionally), or constant.One of the eyes may look in or out, or turn up or down.
Strabismus is present in about 4% of children,but may also occur later in life.Its prevalence in males and females is equal and sometimes may run in families. However, some patients don’t mention a history ofsuch a problem in their family.
Vision and brain
With a normal binocular vision, both eyes look at one point together. Visual section of the brain, mergesthe tworeceived images into one three-dimensional image.
When, because of strabismus, one eye is misaligned, two different pictures are sent to the brain. In a young child, the brain learns to ignore the image of the misaligned eye and onlyaccepts the direct image ofthe eye withbetter vision. This leads to the loss of depth perception and binocular vision.Strabismus that arises in an adult, usually since the brain has acquired the ability to accept the images from both eyes, is accompanied by double vision. In this case, the brain is unable to block the erratic image.Unfortunately in children the deviated eye is not used to focus, and the brain blocks the erratic image which very soon leads to a lazy eye or amblyopia.
Normal alignment of the eyes during childhood provides appropriate vision in this age group. Misalignment of the eyes instrabismus may result in "lazy eye" or amblyopia which is due to brain's ignoring input from affected eye. This is what happens in almost half of the children suffering from strabismus.
Amblyopia Treatment involves making the amblyopic (lazy) eye work harder to see. This is usually done by blocking the vision in the good eye with a patch. If not treated in a timely fashion, it may cause permanent vision problems. The earlier the treatment is started, the better.
Strabismus causes and symptoms:
Six different muscles attached to each eye work together and are in charge of eye movements.In each eye, two muscle move eye to the right or left. The other four muscles move the eye up and down or diagonally. These muscles should work "as a team" so that both eyes can focus on the same object.Strabismus occurs when the eye muscles don't work properly to control eye movement.
The role of the brain in controlling the eye muscles is very important. Thus, children with brain disorders such as cerebral palsy, mental retardation, hydrocephalus and brain tumor
s often have strabismus. Any factor that led to vision loss, such as refractive error, cataracts, eye injuries and… could be a factor for strabismus.
The primary symptom of strabismus is a misaligned eye. Young children may hold their heads to one side if they can use their eyes together in that position. Or, they may close or cover one eye when it deviates, especially in sunlight. Sometimes they complain from headache, sever tired eyesand loss of depth perception. Adults, on the other hand, complain about double vision (see a second image).
Every infant or child should be examined by a pediatric or ophthalmologist, so that the potential problems can be detected. This is much more important in cases where another member of the family suffers from strabismus or amblyopia.A newborn's eyes may be misaligned at first, and diagnosing strabismus is very difficult. In some cases, the eyes may simply seem to be misaligned because the child has a wide bridge of the nose that creates the appearance of crossed eyes.The appearance of strabismus in children will improve gradually as they get older, in contrast with real strabismus. An ophthalmologist can easily distinguish between false and real strabismus.
Strabismus Treatment aims to preserve vision, align the eyes and restore binocular vision. Depending on the cause of strabismus, the treatment may include prescribing glasses, cataract surgery, or straightening and realigning muscles in the eyes. After a complete eye examination including a detailed study of the inner parts, ophthalmologist will decide on a proper optical, medical or surgical treatment. In most cases, patching or covering the better-seeing eye will be necessary.
Esotropia is in fact the inward deviation of the eyes, and is the most common type of strabismus in infants. Young children with Esotropia never use both of their eyes at the same time.
In most cases to align the eyes, restore the binocular vision and prevent permanent vision loss, early surgery will be necessary. Esotropiasurgeryconsistsof weakening and strengthening the appropriate extra ocular muscles.Forexample,the stronger internal muscles of the eye maybe detached and then reattached further back in the eye. This weakens the elasticity of muscles and provides outward rotation of the eye. Sometimes to facilitate the outward movement of the eye, it is possible to shorten the external muscle and thus increase its elasticity.
Accommodative esotropia is the most common form of esotropia in hyperopic (far sighted) children aged 2 years or older .Young children are able to over converge in response to a demand to focus clearly, but it leads to inward deviation of the eyes. To correcting this far sightedness bifocalsglasses are prescribed for children.
Glasses reduce this focusing effort and can straighten the eye. In some cases, the use of a special type of bifocal glasses is necessary (as shown in the figure opposite). And sometimes eye drops and special lenses called prisms (Prism) can be used. Sometimes eye exercises also help to correct this condition in older children.
Exotropia (outward deviation)
Exotropia, or outward deviation of the eye, is another common type of strabismus. This occurs most often when the child focuses on a distant object. It is intermittent and especially show itself when the child is fatigued or stressed. Parents say that their child wrinkles and folds one of his eyelids in front of direct sunlight. Although goggles, eye muscle exercises or prism help to control the outwards rotation of the eye, in most cases, a kind of surgery will be necessary.
Never during any type of surgery, is the eyeball removed from its place. Strabismus surgery is in fact making a small incision in the tissue covering the eye, which allows the ophthalmologist to have access to the underlying muscle tissue. Depending on eye deviation the eye muscles are operated. Sometimes surgery is needed in both eyes.
Strabismus surgery in children is performed under general anaesthesia, but in adults it can be done by local anaesthesia.
Recovery is rapid. Most people can resume their normal activities within a few days. After surgery, sometimes wearing glasses or prisms may be necessary. Sometimes the modification is more or less than the specified amount, in which case a secondsurgery will be necessary.
It is recommended that the corrective surgery for strabismus should be performed as soon as possible, since the infant can regain its normal, binocular vision after its eyes are aligned. On the other hand, being crossed eyes can also have a negative effect on children's self-esteem.
As with any kind of surgery, eye muscle surgery is along with complications. These complications include infection, bleeding, and other rare complications that can lead to loss of vision. However, strabismus surgery is usually a safe and effective treatment, yet it will never replace glasses or amblyopia therapy.
• Child Growth in itself cannot treat strabismus.
• The most effective treatment for strabismus is when the baby is an early age.
• Straightening the eyes is possibleat any age.
• Non-surgical treatment of strabismus may include eye drops, eye exercises or glasses.
• If surgical treatment is needed, the younger the child is, the greater is the chance for binocular vision.