El Strabismus is an eye problem in which one or both eyes deviate and do not align at the same point, causing an alteration of binocular vision.

This is a common condition that primarily affects children, although adults can also be affected. Among the options to treat strabismus we have visual therapy or, in more advanced cases surgery.


El Strabismus is an eye problem in which one or both eyes deviate and do not align at the same point, causing an alteration of binocular vision.

This is a common condition that primarily affects children, although adults can also be affected. Among the options to treat strabismus we have visual therapy or, in more advanced cases surgery.

What is strabismus?

Strabismus, sometimes written by mistake as estrabism or estravism, occurs when there is a deviation in the position of the eyes. When focusing, the patient's gaze is directed at different points instead of settling on the same point.

Usually one of the eyes is fixed while the other is deviated, but sometimes the fixed eye can also deviate. This condition can always occur or manifest intermittently, usually triggered by fatigue or stress.

The strabismus in the eyes usually appears at birth or during childhood, affecting up to 4% of the child population; however, it can also manifest in adults as a symptom of an underlying condition.

Strabismus, if it is corrected on time, May cause lazy eye or amblyopia. Lazy eye occurs when an eye loses vision due to poor coordination with the brain. When this happens, the brain uses the image of the eye that sees better, causing the other eye to become insufficiently stimulated. 

types of strabismus

The strabismus types are:

  • Convergent squint: it is the squint in which the eye affected deviates inward, that is, towards the nasal canthus.
  • Divergent squint: in this type of squint the eye drifts out. This strabismus is less frequent than convergent strabismus.
  • Secondary squint: occur by the visual decline of some structures of the eye, like the difference of graduation between both eyes.
  • Special squints: are caused by mechanical alterations or innervation problems.
  • paralytic strabismus: occurs when a músculo eye has paralysis or problems contracting.
  • alternating strabismus: In this type of strabismus the deviation can occur in one eye or the other indistinctly. The deviation alternates between one eye and the other. When one eye focuses, the other deviates.
  • monocular strabismus: an eye focus correctly no deviation while the other is deflected permanently.


It is recognized by the horizontal deviation of an eye deviated inward. This is the most common type of strabismus and usually manifests between 1 and 3 years of age, but it can appear in adulthood due to problems with the eye muscles.


La exotropia characterized by the horizontal deviation of an eye deviated outward. This strabismus affects women the most and often manifests at 8 years of age.

Causes of strabismus

Strabismus is caused by a muscle imbalance. There are six muscles attached to the outside of each eye that control the movements.

When both eyes are aligned and focusing on an object, the muscles of each eye must be balanced and working together in parallel. However, if the extraocular muscles do not work together and balanced, a misalignment that causes strabismus.

To know how a person with strabismus sees, first we must clarify one aspect: when the eyes are aligned on the same objective, we have binocular vision, and that is that our eyes are designed to focus images clearly on the retina and then send the generated signal to the brain. However, if one of the eyes strays, the brain receives two images instead of one and, in the case of children, decides to ignore the image of the deviant eye, taking as good that of the aligned eye. This can cause the child's vision to be reduced and a condition called lazy eye or amblyopia may appear.


If strabismus appears in adulthoodBecause the brain is used to binocular vision, it will not have the ability to choose the image of the fixed eye and therefore we will suffer from double vision or diplopia, in addition to perceiving images without depth.

Although it is known that the causes of strabismus have to do with the muscle imbalance of the eyes, the exact reason that generates this imbalance is not always known. There is hereditary factor in this condition, but in most cases of child strabismus The underlying cause is unknown, and since it appears at birth or shortly after birth, it is known as congenital strabismus.

Causes of strabismus in babies

Among the most common causes of strabismus in babies we find: 

  • El squint is a hereditary disease. People who have suffered from strabismus are more likely to transmit it genetically to his children.
  • Some brain problem It makes it difficult to control eye alignment. 
  • By the presence of farsightedness.
  • Central nervous system disorders


Causes of strabismus in children

It is important not to confuse strabismus in children with pseudostrabism. Pseudostrabism occurs when one or both eyes appear to be deviant, but in reality they are not. In this case it is not a strabismus type, since both eyes have the ability to focus on the same point at the same time. 

The main causes and pathologies associated with the appearance of childhood strabismus are:

  • Trauma cranial or cerebral.
  • neurological alterations.
  • Retinopathy of prematurity.
  • Rubella congenital.
  • Soft Drinks syndromes of genetic origin.
  • Being hyperopic, a frequent cause in children older than 2 years.


Causes of strabismus in adults

Although it is a more common pathology in children, may also appear in adulthood. Some of the causes of strabismus in adults are:

  • Diabetes.
  • Disease Graves.
  • Eye injuries.
  • Brain injuries.
  • Sight loss derived from an eye disease or injury.
  • Stroke.

In specific cases, strabismus It can appear in adults who have suffered this condition during childhood but that, being controlled or intermittent, has not manifested itself before.

Symptoms of strabismus

Several of the signs of this condition are visible to the naked eye, so that a third party can detect them. Others have to do with the way we perceive the objects and usually manifest themselves in cases of strabismus in adults.

Common symptoms are:

  • Deviation of one eye, lack of alignment in the eyes.
  • Uncoordinated Movements In the eyes.
  • Difficulty focusing near objects and carry out activities that involve this type of approach, such as reading.
  • In the case of adults, double vision.
  • Tiredness and visual heaviness.
  • Problems for perceive the depth of campo.
  • Loss of vision.

Fatigue, fatigue or stress can temporarily worsen strabismus, so it is common that at the end of the day or after periods of stress this condition can be perceived more clearly by a third party. Once the possible deviation of an eye is suspected, a precise examination by the ophthalmologist is necessary to determine the cause and start the treatment.


El ophthalmologist is the professional in charge of diagnosing strabismus. Therefore, if it is suspected that the child suffers from an ocular deviation, it is advisable to go to this specialist as soon as possible, especially if there is a family history. If there is no previous history, from the age of three the first examination can be performed to determine that the vision is adequate.

The ophthalmologist performs different tests of visual acuity, binocular vision study, retinal exam and a corneal light reflex test, among other options, to determine if the patient suffers from strabismus. Because in some cases it is necessary to dilate the pupil, We recommend coming accompanied by someone at the time of carrying out the evaluation.

strabismus treatment

Strabismus treatment

Strabismus treatment it depends directly on the cause that causes it. After conducting a thorough examination of the patient, including the evaluation of the internal structures of the eye, the ophthalmologist should recommend the most appropriate optical, medical or surgical treatment. Covering the dominant eye stimulates the use of the deviated eye and may be necessary to restore vision.

The type of treatment applied will depend also of the strabismus type to suffer The two most common types are:

Treatment without surgery

La visual therapy It is very effective in the treatment of strabismus without surgery, since it allows to strengthen and stimulate the extrinsic muscles through visual exercises.

Vision therapy is of great help to correct the convergence insufficiency if it is carried out in a period of at least 12 weeks. Ideally, therapy should be performed at the eye center and the patient reinforce the treatment by performing exercises at home.

Treatment of strabismus in children

The treatment of strabismus in children includes the following options:

  • Optical correction with glasses to treat a refractive defect associated with strabismus. The option of using glasses with prisms that help the patient to correct double vision can also be evaluated.
  • In some cases, strabismus can be corrected with a botulinum toxin injection. This toxin helps paralyze the muscles that are affecting visual alignment.
  • Visual therapy to stimulate the proper functioning of the extrinsic muscles.

How to treat endotropia?

It occurs when the eye deviates to the nose and is most common strabismus in children. In these cases the child will not learn to read using both eyes together so that the vision of the weakest eye can be affected.

Many times, early surgery is necessary to align the eyes and guarantee the obtaining of good binocular vision and prevent the loss of permanent vision of one of the eyes. The goal of surgery is to adjust the position and muscular tension of one or both eyes so that they align and recover the possibility of focusing the objects simultaneously.

Other endotropia frequent in children with more than two years is the one caused by the need for optical correction. These patients are hyperopic and have the ability to force focusing mechanisms to compensate for the farsightedness, allowing them to see well from afar and up close. Excessive overexertion what they must do to focus the images causes the eyes to drift towards the nose. The solution in these cases is the use of glasses, which reduces and balances the effort made with the eyes, thus disappearing or partially correcting the ocular deviation.

Occasionally they can be used drugs or special lenses called prisms to encourage proper focus and in other cases visual exercises are necessary to help children control their eyes.

How to cure exotropia?

Exotropia appears when the eye deviates out. It usually happens when the child is focusing objects of distant vision and is normally associated with the myopia.

Often this condition is intermittent, that is, it only appears at certain times and especially when the child is tired, fatigued or sick.

Although glasses or the prismatic therapy usually reduce the amount of deviation in some patients, surgery is usually necessary.

Strabismus surgery

La strabismus surgery it is a safe and effective treatment, but it does not replace glasses or amblyopia therapy and one or both eyes can be operated on at the same time.

How it is performed?

During surgery a small incision is made that allows access to the muscles to modify their opposition and with it the tensile forces exerted on the eyes, the selection of the muscle or muscles that must be operated depends on the direction to which the eye is diverted.

General anesthesia is required for children, while local anesthesia may be performed for adults. Recovery time is usually fast and normal activity can be restored within a few days.

Surgery results

Strabismus surgery offers excellent results. Thanks to this operation most patients are able to permanently correct the problem aesthetic causing visual deviation. 

On occasions where the eyes are more aligned but not perfect, we can propose a second strabismus intervention as an adjustment to refine the ocular alignment. Visual therapy exercises after strabismus surgery serve as reinforcement for better coordination between the eyes, vision and their interpretation in the brain. 

Some patients may need, after surgery, the use of prisms or corrective glasses.

Possible complications

Strabismus surgery contemplates the same complications as any surgical intervention, such as infection, bleeding and inflammation. There is also a risk that the ocular axis deviation will reappear over the years. 

Risks of not performing the surgery

Early surgery is recommended in important strabismus because children can develop vision normally., avoiding the appearance of lazy eye or other disorders that affect your vision in the medium term. When the child grows, the chances of achieving normal vision diminish.

In recent years, another type of surgery has been applied through the injection of botulinum toxin to relax the muscle and allow better motility. In all cases, the choice of surgical procedure will strictly depend on the evaluation of a professional.

Área Oftalmológica Avanzada, your clinic to correct strabismus

En Área Oftalmológica Avanzada we have the best human and technological team to carry out strabismus surgery successfully. In our medical center, patients with mutua can undergo strabismus surgery and have a full coverage of the procedure, as well as preoperative and postoperative visits

Those patients who do not have health insurance can opt for our 12-month plan for 100% financing of the intervention. The surgery has a cost of 1.990 euros, which means that the patient can opt for surgical treatment with the financing plan of 12 installments of 179 euros each. Do not hesitate, contact us and correct the strabismus with the best experts in Barcelona.

Article name
We explain what strabismus is, how it is diagnosed, the most recommended treatments and the most common types.
Name of the editor
Área Oftalmológica Avanzada
Editor's logo