Index
It is a condition (found most often in children) where the eyes do not look towards the nose.
Strabismus is one of the most relevant health problems in the world, and infantile esotropia is perhaps the most visually significant and the least understood. An esotropia is the medical name for a convergent strabismus in which one eye turns towards the nose.
Convergent strabismus can appear all the time or only when the child is tired, ill, or focused on a near or distant object.
Generally, while one eye looks forward to focus on an object, the other eye is not aligned with the other and turns inward.
Convergent strabismus, or esotropia , is one of the most common forms of strabismus ( crossed eye ). It refers to the crossing of the eyes caused by the focusing efforts of the eyes when trying to see clearly.
The closer an object is to the eye, the greater the amount of accommodation that is required. A side effect of the accommodation effort can be excess convergence or crossing of the eyes.
Patients with convergent strabismus are usually hypermoto (hyperopia). This means that the eyes have to work harder to see clearly, especially when the object of the gaze is up close. This focus effort is called hosting.
Congenital convergent strabismus
Congenital means from birth and, using this strict definition, most babies are born with eyes that are not aligned at birth. Only 23% of babies are born with straight eyes.
In most cases, one eye, the other, or both actually drift inward during the neonatal period. Within the first three months, the eyes gradually align more consistently as the coordination of the two eyes develops as a team develops.
It is common for babies to appear as if they have esotropia or internal eye roll, because the bridge of the nose is not fully developed. This false or simulated appearance of an inward turn is known as an epicanthus.
As the baby grows, and the bridge narrows to show more of the whites of the eyes (sclera) on the inner side, the eyes will appear more normal.
True congenital convergent strabismus is an inward turn of a large number, and is present in very few children, but the baby will not grow out of this turn. True infantile esotropia usually appears between 2 and 4 months of age.
General pathology
Accommodative esotropia is the most common subtype of convergent strabismus, with onset after 1 year of age and is usually detected around 2-3 years of age. There is no predilection for esotropia in terms of age or gender.
Convergent esotropia or strabismus is a common pathology in early age, generally followed by unilateral functional amblyopia of the eye that deviates if an adapted treatment is not prescribed very early.
Amblyopia occurs when the subject has lost the use of one eye, now it is constantly deviating. Every child with strabismus should have an early comprehensive eye exam.
Which eye appears to be affected?
Either left or right, or alternating, where the strabismus can alternate from one eye to the other.
How the eye turns: if the turn is inward it is called convergent squint or esotropia, if the turn is outward it is called divergent squint or exotropia, if the turn is upward it is called hypertropia , if the turn is downward, it is called hypotropia.
This means that your child’s strabismus can be carefully categorized by the professionals involved and they can describe your child’s strabismus with a combination of these words, for example, an ‘intermittent convergent strabismus’.
Knowing the nature of your child’s strabismus and labeling it as accurately as possible can help you decide how to fix it.
History of convergent strabismus
The exact cause of convergent strabismus remains unknown. While some believe that esotropia is due to excessive tonic convergence, few agree with what explains such conditions.
It is worth believing that convergent strabismus is an innate and irreversible fusion defect. As such, it is a primary dysfunction in the normal development of binocular sensitivity.
This was countered by Chavasse, who stated that the neural components necessary for normal binocular vision are present in strabismic individuals at birth.
But the development of the fusion is eventually impeded by abnormalities of the optic entrance (eg, monocular cataracts) or by the muscular exit (eg, cranial nerve palsy).
The origins of convergent strabismus are equally undefined. A few authors have implicated virtually everything from and even the extraocular muscles to the visual cortex in causing convergent strabismus.
Although understanding the mechanisms behind convergent strabismus has come a long way, there is still a long way to go to discover and clearly understand such an elusive condition.
Understanding the eye muscles
Convergent esotropia or strabismus is an ocular misalignment in which one eye deviates inward, or nasally. The deviation can be constant or intermittent. The deviating eye can always be the same eye or it can alternate between the two eyes.
The movement of each eye is controlled by six muscles that are responsible for generating all the movements of the eyes in their bony sockets.
With the exception of the lower oblique, when considered together, these muscles take the shape of a cone that allows them to pull the eye in specific directions. The medial rectus muscle pushes the eye inward and the lateral rectus outward.
The upper rectus is responsible for the upward movements of the eye and in the opposite direction, the lower rectus muscle mostly pushes the eye downward.
To help stabilize eye movements, the upper and lower oblique muscles are responsible for the rotation of the eye and assist the rectus muscles in their movements.
How does the vision develop?
When you are born, your eyes and your brain have to learn to work together. As you get older, you use your eyes to collect information that is sent to the brain for processing, and this creates a connection between them.
This connection between the eyes and the brain is known as the visual pathway.
The visual pathway develops throughout childhood and up to seven or eight years of age. During this time, it is important that your eyes send clear and similar images to your brain.
Your eyes and brain use your visual experiences to improve your coordination and allow your visual path to develop as much as possible.
This allows a good level of vision to develop in each eye separately, as well as allowing the two eyes to work together as a pair to allow you to see in 3D.
After the age of about eight years, the visual pathways and the parts of the brain that “see” are fully formed and difficult to change. That is why it is important to treat children’s vision problems before this age.
How can it affect vision?
If your child develops a convergent strabismus, it means that each eye is looking inward and their eyes are sending different images to the brain.
Your brain finds it difficult to merge the two images into one clear image because the images are so different. This means that your eyes have stopped working together and that, usually, in an adult, they cause double vision.
However, since your child’s visual system is still developing, the brain can easily adapt to stop this double vision by ignoring the image coming from the eye with the squint.
They will use only your best / direct eye vision. The brain that “turns off” vision in the eye by squinting is called “suppression,” and this can cause vision in that eye to become poor because it is not being used.
Children can easily adapt to using one eye and it may not be obvious from the way they act that they have a vision and eye problem.
This can only be detected by having your child’s eye tested by an eye health professional.
Amblyopia
Amblyopia occurs when the visual pathway does not develop properly in one eye because that eye cannot send a clear image to the brain.
This causes blurred vision in that eye, even when a child wears the correct glasses. An eye that has amblyopia can be called an amblyopic eye or a “lazy” eye.
A child with a convergent strabismus may develop amblyopia in the eye that has the turn, because the vision in this eye is not being used by the brain.
Some children may have amblyopia, but they may not have convergent or divergent strabismus. This may be because one or both eyes are particularly nearsighted (nearsighted), farsighted (farsighted), and / or have high astigmatism.
Amblyopia can lead to a permanent reduction in how well this eye can see. There are different ways to treat an amblyopic eye, and treatment is most successful when vision is still developing before age seven or eight.
Unfortunately, amblyopia cannot be easily repaired later in life, so it is very important that strabismus and amblyopia are picked up early and treated.
Reduced binocular vision
A convergent squint means that the two eyes are not working together. This can reduce your child’s 3D or binocular vision.
Binocular and 3D vision allow you to have depth perception (also known as stereopsis). This helps you judge how far away things are.
Living with convergent strabismus
The baby with convergent strabismus is usually crossed with fixations, which means that he uses either eye to look in the opposite direction. The right eye is used to look to the left side, and the left eye is used to look to the right side.
By definition, they alternate with which eye they are looking at. It is more difficult to help this type of strabismus with non-surgical methods, such as vision therapy and / or glasses.
Sometimes a transparent tape applied to the inner third of each lens (occlusion) can reduce the tendency to turn inward. Prisms can help alignment if the twist is not too great.
Some children who develop strabismus, in whom coordination between the two eyes is poor, also have atypical patterns of gross motor development.
They usually skip the drag stage with bilateral movements, and go straight from crawling to standing.
The interaction between gross motor skills, particularly the balance systems (cerebellar and vestibular) and the binocular systems (motor control of the two eyes) is also evident in the large number of young children with cerebral palsy who have strabismus.
If the inward turn of the eye is constant and large, surgery may be indicated. However, keep in mind that both the parent and the surgeon must commit to multiple procedures to obtain a perfect alignment of the two eyes for the patient.
Furthermore, even multiple surgeries or “revisions” can end up providing cosmetic benefits only. That is, the two eyes may appear normal or “straight” to outside observers, but normal vision with two eyes has not been achieved.
The improvement can only be cosmetic, since the surgery does not necessarily allow the brain to use the information from both eyes simultaneously (binocular vision).
So eye teaming, eye tracking, stereoptic vision, and / or 3D depth perception are often poor after surgical treatment.
If surgery is performed, the best chance for visual success occurs when the surgeon works with a developmental optometrist who is comfortable prescribing glasses and Optometric Vision Therapy to encourage perfect alignment of the two eyes with fusion and proper eye gear.
Such a cooperative care model would be similar to the complementary relationship between an orthopedic surgeon and a physical therapist.
The chance of developing binocular vision with surgery alone decreases with age. Older children with convergent strabismus may need both surgery, if the shift is long, and vision therapy before and after surgery.
Smaller twists can best be treated with vision therapy alone Getting the two eyes to work together takes time and effort, but it’s worth it!
Why is convergent strabismus a concern in children?
If a child’s eyes cross at a young age, then vision will not develop normally. Vision can be permanently reduced in one eye if not “used” properly during childhood, and fine depth perception may never develop.
If the crossing of the eyes is diagnosed and treated in time, the development of vision can continue normally.
Crossing of the eyes is never normal (except for occasional crosses in the first three months of life), and any pediatric ophthalmologist should examine any child suspected of having crossed eyes.
Do all children with hyperopia have convergent strabismus?
No, in fact, most children are farsighted, but most of them do not have any esotropia. Most children are short sighted and therefore the accommodation effort they make to see clearly is not significant.
However, the more forward-thinking a person is, the greater the amount of effort they have to put in and the more likely they are to cross their eyes.
Therefore, while two people may have the same ocular prescription strength, one may have crossed eyes and the other may have perfectly straight eyes. Heredity plays a role in determining which children develop esotropia.
The types of convergent strabismus (esotropia)
Children’s Convergent Strabismus
This is an evolution, often constant, that occurs in the first 12 months of life.
It is associated with large angle deviation, latent nystagmus, cross-fixation fixation pattern, normal accommodative convergence to accommodation ratio, and age-appropriate refractive errors.
Accommodative Convergent Strabismus
If excessive inward turning of an eye is first observed around 2 years of age, it may be due to difficulty integrating the focusing system (accommodative) with the eye alignment system (binocular).
They often have a gradual onset and can evolve to constant after a period of intermittence.
Normally when we look across the room or beyond, our eyes are parallel or straight. However, when we look at things closely, two things happen.
We need to converge more (point both eyes inward at the same time) and need to bring in more focus or settle in to keep things clear.
Children have a great deal of power of focus and sometimes to set the record straight, inward turning or convergent strabismus results.
Fully accommodative convergent strabismus is associated with high hyperopia of +3.00 D or greater and inadequate fusion divergence amplitudes.
A subtype of accommodative convergent strabismus is the esotropia excess convergence type, which is associated with a greater deviation at near distance. Near deviation is reduced when housing is relaxed with + 3.00D lenses.
The mechanism is an abnormal relationship between accommodative convergence and accommodation (high accommodative convergence to accommodation relationship); the effort to adapt produces an abnormally high accommodative convergence response.
Partially accommodative convergent strabismus is a residual esotropia that is partially corrected but still persists despite full correction of the hypermetric refractive error.
If the inward turning only occurs up close, such as when playing with small objects, making eye contact, coloring, looking at picture books, etc., the child may only need glasses for close activities to reduce or eliminate convergent strabismus.
However, if a child has significant future vision (farsightedness), an internal turning of the eye can occur when focusing to look further away, such as television.
If the amount of twist is greater near than far, your optometrist may prescribe a multifocal lens.
For children, this could be a traditional bifocal with a line, or a bifocal or progressive lens shape without a line. Your optometrist will review with you which is the best option for your child.
Convergent strabismus partially accommodative
In some cases, part of the inward turn is due to basic convergent strabismus and an additional amount due to the accommodation effect. Glasses can reduce the amount of eye rolling, but they are not fully compensated for.
Initially, the eye doctor may prescribe a prism to compensate for the amount of shift. Office-based vision therapy is often necessary. Surgery remains an option to treat the non-accommodative part of the esotropia.
Remember that surgery alone rarely allows the patient to learn to use both eyes together as a team, and generally leaves the patient with poor stereopsis.
Because vision is a learned process, some form of therapy is often helpful in learning new patterns of binocular vision or in restoring normal pathways that have been lost or underutilized.
Binocular vision occurs in the visual centers of the brain, not in the muscles of the eyes.
Non-accommodative convergent strabismus
This evolution begins after one year of age and is not associated with any accommodative factor.
Esotropic-type divergence insufficiency
This esotropia, more frequently associated with adult patients 30 years of age or older, is characterized by a greater esodeviation in distance than in the near.
The divergence amplitudes in fusion are reduced both at distance and at close fixation, and this esotropia is comitant in primary and lateral gazes.
Microtropia / Monofixation Syndrome
This is characterized by patients with a central scotoma in one eye along with peripheral fusion. These patients generally lack fine stereopsis and maintain a mild to moderate degree of amplitude of fusion.
Sensory convergent strabismus
Unilateral reduced visual acuity, due to various organic causes, presents a barrier to fusion. In children under the age of 4, the blind or visually impaired eye will generally become esotropic.
Older children or adults with sensory visual deprivation will generally develop a sensory exotropia.
Consecutive convergent strabismus
This occurs when a person who was previously exotropic becomes isotropic. Sometimes this is a result of surgical overcorrection for exotropia.
What Causes Convergent Strabismus?
Convergent strabismus usually arises not due to an abnormality in the eye muscle, but due to a weakness in the center of alignment in the brain. In other words, it is generally a control problem, not a muscle problem.
This is generally not associated with any neurological abnormalities. Sometimes there is a true muscle movement problem, and sometimes an eye injury or other general health conditions can also be the cause of the development of a convergent strabismus.
Strabismus, or convergent strabismus, can be inherited and frequently appears in the first months of life, which is known as congenital strabismus. However, they can also appear in older children for no apparent reason.
Convergent strabismus can also be linked to refractive errors when the shape of the eye does not bend light correctly, resulting in a blurry image, such as nearsightedness, astigmatism (where the shape of the eyeball is longer than normal), or farsightedness. (long sighting).
Children with refractive errors may find that their eyes roll inward due to the effort of focusing to see clearly, which can lead to convergent strabismus over time.
It is associated with poor development of stereopsis, movement processing, and eye movements. Amblyopia is a frequent consequence of infantile esotropia.
To date, its exact cause has yet to be identified, and an effective treatment strategy has yet to be formulated.
Some common causes of convergent strabismus can include:
Refractive errors (focus problems)
Refractive errors are very common conditions where there is a problem with the focusing power of the eye. They are usually corrected with glasses. The most common types of refractive error are:
Farsightedness : where the eye focuses better in the distance than when looking closely, and makes the eye work harder to see things clearer up close.
Nearsightedness : which makes your vision blurry at a distance and clearer when you look at things closer.
Astigmatism : which can cause blurred vision up close and in the distance. It is caused by the front of the eye not being quite spherical (round). Astigmatism is very common and most people have some degree of astigmatism.
Farsightedness in children can cause a strabismus to occur when turning the eye (esotropia). Farsightedness in children is the most common cause of esotropia.
Children’s eyes have great focusing power, allowing them to make the things they look at look far and close.
If your child has long-term vision, his eyes will need to focus more to clear his vision, particularly for near vision. This approach is called ‘accommodation’.
When we settle in, our eyes naturally ‘converge’ or point inward, toward the nose. The more a child needs to accommodate, the more their eyes will converge as well.
This means that if a child is spotted and needs to adjust to see better, this can cause their eyes to turn too far towards each other and then they can develop a convergent strabismus (esotropia).
Having glasses to correct your long vision allows you to focus to relax and provide clearer vision. At the same time, the glasses can also straighten the eyes and eliminate convergent strabismus because their over convergence will also be relaxed.
Etiology
The etiology of convergent strabismus is unknown in most cases, but it can be inherited.
Sensory convergent strabismus occurs due to decreased acuity in one eye, due to various organic causes, leading to an inability to maintain the normal alignment of the eye. Strabismus is believed to occur due to a problem with the fusion system.
The symptoms
Symptoms are quite variable in terms of frequency and severity of strabismus. If a child removes the deviated eye, the patient may develop amblyopia or a more severe angle or frequency of strabismus. Adults with convergent strabismus may experience diplopia.
Not just a cosmetic problem
Certainly, the appearance of convergent strabismus can lead to self-esteem problems for a child, but also this condition can become more than an aesthetic problem if it is not treated. For example, the possible effects of a convergent strabismus include:
Loss of binocular vision. If left untreated, the child’s brain will often ignore visual images from the weaker eye, causing amblyopia or “lazy eye.”
Since the eyes are not aligned, amblyopia can damage a child’s deep perception (seeing in 3D) and result in poorer vision in that eye for the rest of the person’s life.
- Double vision.
- Blurry vision.
Risk factor’s
Neurologic disorders, hydrocephalus, prematurity, and a positive family history of strabismus increase the risk of having convergent strabismus.
What are the characteristics of convergent strabismus?
A great glimpse of converging angle.
Children often choose to use their left eye to look at objects to their right and their right eye to look at objects to their left.
This is known as cross fixation. For this reason, children often can’t seem to turn their eyes outward, even though they can.
Equal vision in both eyes.
Although children with infantile convergent strabismus do not use both eyes together before treatment, most are happy to switch from one eye to the other.
Because they tend to use both eyes equally (but not at the same time), they usually develop equal vision in both eyes.
Children with other types of convergent strabismus often prefer to use one eye more than the other and are at increased risk of developing amblyopia (a lazy eye).
Mild degree of long vision
Most children under the age of 1 are moderately long, but do not require glasses. However, some children with convergent strabismus may have longer than normal vision and will need glasses.
Wearing these long-sight glasses can sometimes reduce the size of the inward turn.
Drift up from the eyes
An upward movement of the eyes when the child looks to the opposite side is often seen in children with convergent strabismus. This is caused by an over-action of a muscle called the lower oblique muscle.
Occasionally, one eye may have a tendency to spontaneously lift upward. This is called dissociated vertical deviation (DVD). Dissociated vertical deviation is usually not present before the age of 2-3 years.
It is quite common for excess lower oblique action and dissociated vertical deviation to occur together.
Shaky eyes
The medical term for trembling eyes is nystagmus. Some children with convergent strabismus have a mild form of nystagmus, which only occurs when one of their eyes is covered or closed. This is called latent nystagmus.
Diagnosis
Physical exam
All patients with convergent strabismus would require a complete ophthalmologic examination, including visual acuity, binocular function and stereopsis, evaluation of motility, measurements of strabismus near, distance and cardinal gaze positions, measurement of fusion amplitudes, cycloplegic refraction.
Some cases may require a 4-prism diopter base test for microtropy, strabismus measurements after Marlowe’s prolonged occlusion test, strabismus measurements after +3.00 lenses near fixation, evaluation of ocular structures in segments anterior and posterior.
Clinical diagnosis
Children with convergent strabismus often alternate fixation between the eyes and may cross-fix, that is, look to the left with the right eye and to the right with the left eye.
The misalignment is enough for family members to see that there is a problem. Some children fixate almost completely with one eye and risk permanent loss of visual acuity (developmental amblyopia) in the other.
An ophthalmologist should examine the eyes for farsightedness.
Children’s Convergent Strabismus
A baby with convergent strabismus that is usually constant and presents within the first year of life. It is associated with large angle deviation, latent nystagmus, cross fixation, normal accommodation or convergence relationship, and age-appropriate refractive errors.
Accommodative Convergent Strabismus
It occurs in children older than 1 year of age. In general, this is associated with hyperopia, which reduces the angle and / or frequency of convergent strabismus when using hyperopic correction.
Convergent accommodative strabismus can also be associated with microtropia / monofixation syndrome.
Non-accommodative convergent strabismus
This subtype has an onset after 1 year of age, can be constant or intermittent, and is not affected by the level of accommodation.
Esotropic-type divergence insufficiency
This type of convergent strabismus is found in the population 30 years of age and older. These patients have reduced divergence amplitudes at fusion, convergent strabismus is worse at distance than near, and may have trouble driving or diplopia with distance fixation.
Microtropia / Monofixation Syndrome
This is characterized by patients with a central scotoma in one eye along with peripheral fusion, fusion amplitudes, and general stereopsis.
Differential diagnosis
Other conditions that may show convergent strabismus include Duane syndrome type 1 or 3, sixth sixth palsy, nystagmus block syndrome, Moebius syndrome, thyroid eye disease, myasthenia gravis, congenital fibrosis of the extraocular muscles, lateral rectus muscle slipped or rectus muscle.
Abducens palsy must be distinguished from congenital convergent strabismus, which also presents with a normal course but is comitant and is usually not seen before 6 to 8 weeks of age.
A horizontal gaze palsy (caused by an ipsilateral lesion of the abducens nucleus or the paramedian pontine reticular formation) requires the patient to turn the head to see in the affected direction of gaze.
This can simulate unilateral abducens palsy, in which the patient turns the head to avoid the development of diplopia. In abductee paralyzes, however, diplopia and head turning are eliminated by patches on the paretic eye.
The spasm of the near reflex (convergence spasm) can limit abduction and thus simulate bilateral abducens palsies.
Often caused by head trauma and less commonly seen with Arnold-Chiari malformations or other disorders, it is accentuated by close vision and can be identified on the basis of pupillary constriction that is part of the near reflex.
Lateral rectus weakness is occasionally seen with pediatric myasthenia gravis and thyroid eye disease. Orbital pseudotumor and orbital myositis can cause restriction of lateral rectus contraction.
Medial rectus restriction or contracture may mimic or result from cranial nerve VI palsy.
Unlike cyclic oculomotor palsy, cyclic esotropia, which can follow traumatic abducens palsy, is not due to true nerve paresis.
Affected children alternate between 12, 24, 36, or 48-hour periods of normal alignment and periods of similar duration during which esotropias develop. Despite intermittent strabismus, a wide range of eye movements is preserved.
Treatment options
Treatment for convergent strabismus may include a combination of lenses, patches, eye drops, eye exercises, and eye muscle surgery.
Children suspected of having convergent strabismus should be seen promptly by an eye specialist, as strabismus can generally be corrected when found early and treated.
Non surgical
Nonsurgical treatments include patching, correction of total hyperopia refractive error, and divergence orthopedic exercises for divergence insufficiency.
Fresnel prisms or prism lenses can be used to alleviate diplopia or asthenopia in certain patients. Sometimes sensory convergent strabismus can be relieved by treating the underlying cause (amblyopia, cataract, media clouding).
Eyeglasses
The initial treatment for accommodative esotropia usually involves the prescription of glasses or contact lenses to correct the patient’s error (farsightedness). By letting the glasses do the work, the eyes can relax their focus or accommodation effort.
In some cases, by reducing the focus effort on the eyes, wearing glasses is sometimes enough to straighten the child’s eyes and correct strabismus.
In turn, this will reduce the toe-in or crossover stimulus and the eyes will straighten as they relax. Glasses or contacts used to treat convergent strabismus must be worn full time.
What happens after a child starts wearing glasses?
Even after a child has worn glasses to treat accommodative esotropia, it is normal for the eyes to continue to cross without the glasses. In fact, the crossover may be even more noticeable than it was before the child started wearing glasses.
The important thing is whether the eyes are straight and controlled with the glasses on. If the eyes are not straight with the glasses on, then two-eyed vision will not develop normally.
Your pediatric ophthalmologist is the best person to judge this and will give you feedback at follow-up exams.
These follow-up exams are important not only to monitor the crossing of the eyes, but also to detect associated problems, such as amblyopia (decreased vision in one or both eyes, which is common in this type of strabismus).
Why do some children with convergent strabismus require bifocals?
In some cases, children will have particularly excessive amounts of eye crossing (convergent strabismus / esotropia) nearby, such as during reading.
This can occur even when the correct glasses are worn to correct their farsightedness (farsightedness) and they can have perfectly straight eyes when looking at distant objects.
Convergent strabismus with amblyopia (lazy eye)
If amblyopia is present, therapy that includes eye patches is often required for the developed ‘lazy’ eye to develop the ability to see and the preferred eye. If surgery is chosen as a treatment option, it is better to make the eye lazy.
Therapy before surgery. These children can benefit from making the lower reading area of the glasses “extra strong” in the form of a bifocal lens.
Accommodative convergent strabismus with corrective glasses
When the eyes are aligned by corrective lenses, sometimes the eyes spontaneously begin to work together.
Other times, they need help. Remember, the habit of suppressing or turning off one eye or the other probably developed over several years.
The eyes must be trained to rework together and the suppression must be removed to restore normal eye formation, depth perception, and stereopsis.
The ophthalmologist may need to patch an eye that has been removed or dull and / or employ vision therapy.
Intermittent twists usually do not require long-term treatment. Vision therapy may be necessary to improve muscle coordination and eventually eliminate the bifocal.
Patients with accommodative convergent strabismus should never have eye muscle surgery to eliminate the need for glasses. If they do, they will have significant focus problems when they grow up.
In the future, these patients could be excellent candidates for refractive surgery (hypermetropic LASIX) or contact lenses. This should be coordinated with the developmental optometrist and LASIK surgeon.
Eye muscle surgery
Eye muscle surgery is often the recommended treatment option if glasses, patches, and / or eye drops cannot repair a child’s strabismus.
Surgery for convergent strabismus involves tightening the weaker muscles in the eyes and loosening the weaker ones, using special dissolvable stitches to hold the eye muscles in place.
Surgery is performed on the extraocular muscles in an attempt to give unique binocular vision, to alleviate diplopia, or to restore the eyes to their regular state of alignment.
The prognosis for surgical success is better if the patient has intermittent rather than constant convergent strabismus, alternating esotropia, and if amblyopia is treated.
In certain cases, the amblyopia may not be completely corrected due to strabismus and surgery may be needed before complete correction of the amblyopia.
The optimal time for surgical intervention is as early as possible before any degeneration of the lateral geniculate nucleus. Studies have shown that surgeries from six months of age can be effective.
Most children will be able to go home the same day as the surgery.
What role does surgery play in convergent strabismus?
Surgery is indicated only if the glasses do not straighten the eyes while they are in place. In this case, eye muscle surgery (strabismus surgery) may be recommended to help improve eye alignment.
This surgery is usually performed in childhood to help promote the development of binocular vision.
Generally, surgery for convergent strabismus does not eliminate the need for glasses, but rather corrects the number of crosses that are “left over” when the glasses are on. The eyes will likely continue to cross when the glasses are off.
Eye exercises
Unfortunately, there is only one relatively rare form of strabismus that can be treated with eye exercises.
Eye patch
Patching one eye for a few hours each day does not fix strabismus, but it is often used to treat poor vision that can arise from strabismus.
While most children get used to wearing the patch, as it becomes part of their daily routine, this treatment option can be difficult for younger children.
More especially, it can be difficult to get a baby or young child to agree to wear an eye patch and keep it on.
Eye drops
In the event that a child refuses to wear an eye patch, eye drops might be a more suitable treatment option.
Eye drops (called atropine drops) are given into the straight eye to blur the vision in that eye, making the weaker eye work harder.
This method of treatment works in the same way as the patch: it makes the weaker eye do all the work to strengthen vision. Like the patch drops do not straighten the eyes.
What are the goals of treatment?
To realign the eyes and in doing so try to restore some kind of stereopsis (3D vision). Ensure that the child develops equal vision in both eyes.
epidemiology
Strabismus is one of the most prevalent eye problems among children, affecting 5 out of 100 US citizens, or approximately 12 million people in a population of 245 million. Convergent strabismus accounts for 28-54% of all esotropias.
A population-based study from 1965 to 1994 reports that the prevalence at birth of convergent strabismus is 25 per 10,000 or 1 in 403 live births.
It is believed to affect approximately 1% of healthy term newborns and a much higher percentage of newborns with perinatal complications due to prematurity or hypoxic / ischemic encephalopathy.
In an attempt to determine whether convergent strabismus is present at birth or develops later in childhood, Nixon et al looked at 1,219 alert babies in a normal newborn at a city hospital and noted that only 40 babies (3.2 %) had convergent strabismus.
Intermittent convergent strabismus in 17 patients, with 14 patients varying between esotropia and exotropia, and 9 patients with variable convergent strabismus.
Furthermore, no infant showed characteristic features of infantile esotropia. As such, convergent strabismus is not believed to be connatal, but rather develops in the first weeks or months after birth.
Greenberg et al reported an age- and age-adjusted annual incidence of convergent strabismus of 111 per 100,000 patients younger than 19 years.
This rate corresponds to a cumulative prevalence of approximately 2% of all children under 6 years of age, with a significant decrease in older ages.
The incidence of convergent strabismus from this population-based study is comparable to prevalence rates among Western populations.
Convergent strabismus is most common during the first decade of life, with the accommodative and acquired non-adaptive forms occurring more frequently.
Morbidity and mortality
Convergent strabismus is believed to be associated with an increased prevalence of coexisting neurological, ocular, and craniofacial abnormalities.
To a lesser degree, convergent strabismus has also been associated with a high prevalence of systemic disorders, including prematurity, neurology, and genetic disorders.
There have been published reports of coexisting brain lesions (eg, periventricular leukomalacia, enlargement of the lateral ventricles with hypoplasia of the corpus callosum, delayed myelination in the anterior horn adjacent to the lateral ventricles).
Years
By definition, convergent strabismus is seen in babies before 6 months of age.
Looking to the future
Each case of strabismus is unique and treatment options should be discussed with your ophthalmologist as soon as possible.
Early diagnosis and treatment are the best chances for a child to keep his eyes straight and develop good vision and insight.
Also from a social point of view, having eyes aligned is important for a child’s self-esteem and confidence.
Regular eye exams are the best way to detect strabismus. So if you are concerned that your child has developed a squint, make an appointment with one of our expertly trained ophthalmologists to have it checked out.
Can children overcome convergent strabismus?
Yes, children can overcome convergent strabismus. This usually occurs during elementary school and the teenage years when a child loses future vision. It is difficult to predict from an early age whether or not a given child will outgrow their need for glasses.
