Index
Eye alignment problems are common, especially in children.
If you’ve ever tried to have a conversation with someone with an eye alignment or eye roll problem, you may remember which of their eyes you should fix your gaze on.
Eye alignment problems, such as diplopia and double vision , are usually caused by the inability of the eyes to work together. Equipment problems of the eyes can be caused by phias and tropias.
Your ophthalmologist may talk about eye problems like phias and tropias. These terms are used to describe deviations of the eye muscles.
Strabismus is a broad medical term that refers to various misalignments (deviations) of the eye, such as “crossed eyes.”
In order for the two eyes to be aligned correctly, they need to have similar vision and focus ability, and the muscles that move them need to work together.
Only then can a person have binocular vision and depth perception, which means that the images from each eye are fused (mixed) with the brain into a single image that appears three-dimensional. If one eye does not look in the same direction as the other, binocular vision cannot exist.
In a young child, the deviated eye may eventually lose its ability to see clearly. This is called amblyopia or “lazy eye.”
“Comitant” strabismus, the type usually seen in children, means that no matter which way the eyes are viewed, the amount of misalignment (deviation) is the same.
This is in contrast to incomitant strabismus, in which the amount of deviation constantly changes, depending on the direction in which you look.
Strabismus affects approximately two to four percent of all children (boys and girls alike) and tends to run in families.
What is a tropia?
“Tropia” is another word for strabismus (as in esotropia). “Foria” is a related condition in which misalignment is not apparent. It is just a trend, and it is usually kept in check so that the eyes appear normal and function normally.
Misalignment can be unmasked by covering either eye.) The phenias are named in the same way as the tropias: oesophoria (tendency for one eye), exophoria (outside), hyperphoria (top), and hypophoria (bottom).
Most phoria do not cause any symptoms. But if the phoria is large, it may take a lot of effort to keep the eyes aligned and working together to avoid seeing double, and this can cause eyestrain and headache.
Sometimes when the strabismus is intermittent, the eyes remain aligned and appear straight at times, but fall into strabismus at other times.
Tropia is more likely to occur late in the day, outside bright, or when you’re sick. As the years go by, intermittent strabismus tends to be more constant and less intermittent.
What Causes Strabismus?
Very often, there is no identifiable cause: the child is simply born with a misalignment or develops it early in infancy.
False or tropias can be caused by a variety of factors. One of the most common causes is having a large amount of farsightedness. When young children have a large amount of undiagnosed farsightedness, they struggle to look good.
To compensate, they focus harder. Because the focusing system and the converging system of the eye muscle are linked, something gives.
Their brains either decide to see clearly, but one eye turns around or they decide to see blurry and the eyes remain straight.
This is abnormal and they can develop esotropia. This circumstance describes what is called an accommodative esotropia.
But there are also many known causes, for example: an eye that is blind or has poor vision from birth (such as from a congenital cataract).
An eye that is extremely myopic or astigmatic, or the amount of spectacle correction required by the two eyes is very different.
One or more missing, damaged, or defective nerves in the eye muscles, causing the muscles controlled by the nerve to malfunction.
Damage to an area of the brain related to eye movement or eye muscle control; trauma injury that damages eye muscles or nerves; blindness from illness or injury.
Intentionally crossing the eyes is never a cause of strabismus; the eyes cannot “get stuck” in a crossed position.
Types and symptoms of strabismus
Eye doctors classify phorias and tropias by direction.
- Exotropia or exophoria : one eye turns outward.
- Exotropia or esophoria : one eye turns inward.
- Hypertropia or hyperphoria : one eye turns upward.
- Hypotropia or hypophoria : one eye turns downward.
Eye doctors also categorize them as right or left eye or alternate between eyes. They can also be labeled as intermittent or constant.
The most common type, in which one eye turns inward (crossed eyes), is esotropia. It is also called “convergent strabismus” because the eyes converge or turn toward each other.
With exotropia (wall eyes), an eye results; Also called “divergent strabismus.” Less common are hypertropia (one eye turns upward) and hypotropia (one eye turns downward).
In some people, it is always the same eye that wanders. In others, the deviation changes from one eye to another; This is called alternation.
Alternating strabismus can be confusing for parents. Notice that one eye appears to turn, and just when it has concluded which it is, the other eye appears to be the culprit.
“Adult-onset strabismus” is any misalignment that occurs after normal binocular vision develops (usually by the age of 8 years).
Unlike childhood strabismus, the adult type generally creates symptoms, such as double vision (diplopia), which can be accompanied by nausea.
Psychosocial effects
People of all ages who have noticeable strabismus can experience psychosocial difficulties. Attention has also been drawn to the possible socioeconomic impact resulting from cases of detectable strabismus.
There is also a socioeconomic consideration in the context of decisions about the treatment of strabismus, including efforts to restore binocular vision and the possibility of recovery from stereopsis.
A study has shown that children with strabismus exhibit behaviors characterized by a higher degree of inhibition, anxiety, and emotional distress, which often lead to outright emotional disorders.
These disorders are often related to a negative perception of the child by peers.
This is due not only to an altered aesthetic appearance, but also to the inherent symbolic nature of the eye and gaze, and the vitally important role they play in an individual’s life as social components.
For some, these problems improved dramatically after strabismus surgery.
In particular, strabismus interferes with normal eye contact, often causing embarrassment, anger, and feelings of discomfort, affecting social communication in a fundamental way, with a possible negative effect on self-esteem.
Children with strabismus, particularly those with exotropia (an outward turn), may be more likely to develop a mental health disorder than children with normal vision.
Researchers have theorized that esotropia (an inward turn) was not associated with a greater propensity for mental illness due to the age range of the participants, as well as a shorter follow-up period; esotropic children were monitored at an average age of 15.8 years, compared with 20.3 years for the exotropic group.
A later study with participants from the same area monitored patients with congenital esotropia for a longer period of time.
The results indicated that esotropic patients were also more likely to develop some type of mental illness in early adulthood, similar to those with constant exotropia, intermittent exotropia, or convergence insufficiency.
Adult and child observers perceived a right heterotropia as more disturbing than a left heterotropia, and child observers perceived an esotropia as “worse” than an exotropia.
Successful surgical correction of strabismus, in both adult and child patients, has been shown to have a significantly positive effect on psychological well-being.
There is very little research on the coping strategies employed by adult strabismus.
One study classified coping methods into three subcategories: avoidance (refraining from participating in an activity), distraction (diverting attention from the condition), and adjustment (focusing on an activity differently).
The study authors suggested that people with strabismus may benefit from psychosocial support, such as interpersonal skills training.
No studies have evaluated whether psychosocial interventions have had any benefit in individuals undergoing strabismus surgery.
Strabismus can be seen in Down syndrome, Loeys-Dietz syndrome, cerebral palsy, and Edwards syndrome. The risk increases among those with a family history of the condition.
Pathophysiology
The extraocular muscles control the position of the eyes. Therefore, a problem with the muscles or the nerves that control them can cause paralytic strabismus. The extraocular muscles are controlled by cranial nerves III, IV, and VI.
A cranial nerve III disorder causes the associated eye to drift downward and outward and may or may not affect the size of the pupil.
The IV cranial nerve alteration, which may be congenital, causes the eye to move upward and perhaps slightly inward.
Sixth nerve palsy causes the eyes to drift inward and has many causes due to the relatively long path of the nerve.
Increased cranial pressure can compress the nerve as it runs between the clivus and the brainstem. Also, if the doctor is not careful, twisting the baby’s neck during forceps delivery can damage the sixth cranial nerve.
Evidence indicates that the cause of strabismus may be in the proportionate input to the visual cortex. This allows strabismus to occur without direct disruption of the cranial nerves or extraocular muscles.
Strabismus can cause amblyopia because the brain ignores one eye. Amblyopia is the failure of one or both eyes to achieve normal visual acuity despite normal structural health.
During the first seven to eight years of life, the brain learns how to interpret the signals that come from the eye through a process called visual development.
Development can be interrupted by strabismus if the child always fixes with one eye and seldom or never fixes with the other. To avoid double vision, the signal from the deviated eye is suppressed and the constant suppression of one eye causes a failure in the visual development of that eye.
Also, amblyopia can cause strabismus. If there is a large difference in clarity between the left and right eye images, the input may be insufficient to correctly reposition the eyes.
Other causes of a visual difference between the right and left eyes, such as asymmetric cataracts, refractive error, or other eye diseases, can also cause or worsen strabismus.
Accommodative esotropia is a form of strabismus caused by a refractive error in one or both eyes.
Due to the near triad, when a patient adjusts to focus on a nearby object, there is an increase in the signal sent by cranial nerve III to the medial rectus muscles, drawing the eyes inward; This is called an accommodation reflex.
If the necessary accommodation is more than the usual amount, as in the case of people with significant farsightedness, the additional convergence can cause the eyes to cross.
Diagnosis
An optometrist can diagnose strabismus through a comprehensive eye exam. Strabismus tests, with special emphasis on how the eyes focus and move, may include:
Exam
You should examine the eyes as soon as you suspect that they may be crossing or wandering, no matter how small the misalignment. No child is too young to be seen and early attention can prevent later headaches.
The earlier treatment is started, the greater the chances that your child will achieve normal vision in each eye and good binocular depth perception. Correction after 6 or 7 years is more difficult and the result is less satisfactory.
Your ophthalmologist may want to measure the alignment of your eyes. During the coverage test portion of an eye exam, your ophthalmologist will alternately cover and uncover your eyes while looking at a target.
If your eye moves when discovered, you have a phoria. A phoria is a latent deviation, or misalignment, of the eyes that is only apparent sometimes.
Some people have a larger than normal phoria that they can compensate for most of the time. However, because the phoria is much larger than is considered normal, they cannot always compensate for it when they are fatigued.
As a result, your phoria can manifest itself and become a tropia. If there is a large amount of phoria, your eyes do not point to the target while you are at rest.
Keeping your eyes fixed on the target requires effort on your part, possibly causing eyestrain or headaches.
Administration and treatment
As with other binocular vision disorders, the primary goal is comfortable, single, clear, and normal binocular vision at all gaze distances and directions.
Strabismus is usually treated with a combination of glasses, vision therapy, and surgery, depending on the underlying reason for the misalignment.
While amblyopia (lazy eye), if minor and detected early, can often be corrected with the use of a dominant eye patch and / or vision therapy, the use of eye patches is unlikely change the angle of the strabismus.
Treatment objectives
For children, your doctor will try to achieve normal appearance, good vision in each eye (with or without glasses), binocular vision, and depth perception.
In adults, the goals are binocular vision (which eliminates double vision) and relief of any discomfort.
If an adult has a childhood strabismus that was never treated, it is too late to improve amblyopia or depth perception, so the goal may be simply cosmetic: to make the eyes appear correctly aligned, although sometimes the treatment is increased. the range of side vision.
Glasses
In accommodative esotropia, the eyes turn inward due to the effort of focusing the myopic eyes.
And the treatment of this type of strabismus necessarily involves a refractive correction, which is usually done through corrective lenses or contact lenses.
And in these surgical cases alignment is considered only if such correction does not resolve the eye roll.
In case of strong anisometropia, contact lenses may be preferable to glasses because they avoid the problem of visual disparities due to size differences (aniseikonia) that are otherwise caused by glasses in which the refractive power is very different for both eyes.
In some cases of strabic children with anisometropic amblyopia, balancing of the refractive error eyes has been performed through refractive surgery prior to performing strabismus surgery.
Early treatment of strabismus when the person is a baby can reduce the chance of developing amblyopia and deep perception problems.
However, a review of randomized controlled trials concluded that the use of corrective glasses to prevent strabismus is not supported by existing research.
Most children eventually recover from amblyopia if they have had the benefit of corrective patches and lenses.
Amblyopia has long been considered permanent if it is not treated in a critical period, that is, before the age of seven; however, recent discoveries give reasons to challenge this view and to adapt the earlier notion of a critical period to explain recovery from stereopsis in adults.
Eyes that remain misaligned can still develop visual problems. Although not a cure for strabismus, prism lenses can also be used to provide some temporary comfort and to prevent double vision.
Orthoptic exercises
In cases of mild or intermittent misalignment, orthoptic exercises are occasionally helpful, but only in very specific circumstances. If used improperly, orthoptics can be wasteful and can delay the start of proper treatment.
Patch
The ‘patch’ is the main treatment for infants and young children who have poor vision (amblyopia) associated with strabismus.
A patch is placed over the normal eye (preferred eye), to force the deviated eye (amblyopia) to use until vision improves and evens out. Generally, surgery is postponed until that happens.
In adults, an eye patch is a method of eliminating any double vision. Built-in prisms in the glasses is another.
Surgery
Strabismus surgery does not eliminate the need for a child to wear glasses. It is currently unknown whether there are differences in completing strabismus surgery before or after amblyopia therapy in children.
Strabismus surgery attempts to align the eyes by shortening, lengthening, or changing the position of one or more of the extraocular eye muscles.
Surgery is sometimes done in babies as young as a few months old when there is a good chance of getting binocular vision. Children require general anesthesia. Adults often prefer to have a venue.
During the first month or two after surgery, exercises can be designed to re-develop the ability to use both eyes together normally.
The procedure can usually be done in about an hour and requires six to eight weeks for recovery.
Adjustable sutures can be used to allow refinement of eye alignment in the early postoperative period.
Double vision can rarely result, especially immediately after surgery, and vision loss is very rare. Glasses affect position by changing a person’s reaction to focus.
Prisms change the way that light, and therefore images, hits the eye, simulating a change in the position of the eye.
Strabismus surgery is quite safe, although it does carry some risks, as does any surgery and anesthesia. If an operation is necessary for you, your doctor will explain the risks along with the potential benefits.
Many times, more than one operation is necessary to obtain a good alignment of the eye. Glasses may also be required after surgery to obtain the best possible visual result.
Medication
Medication is used for strabismus in certain circumstances. In 1989, the Food and Drug Administration (FDA) approved botulinum toxin therapy for strabismus in patients older than 12 years.
Most commonly used in adults, the technique is also used to treat children, particularly children affected by infantile esotropia.
The toxin is injected into the strongest muscle, causing temporary and partial paralysis. The treatment may need to be repeated three to four months later, once the paralysis subsides.
Common side effects are double vision, droopy eyelid, overcorrection, and no effect. Side effects usually resolve within three to four months as well.
Botulinum toxin therapy has been reported to be as successful as strabismus surgery for people with binocular vision and less successful than surgery for those without binocular vision.
The outcome of treatment depends on many factors, such as the type of strabismus, the age of onset, and the visual acuity of each eye. It often takes years of commitment and care.
Most patients can obtain comfort and a highly acceptable appearance with good eye alignment; some also obtain a completely normal function, with the coordinated use of both eyes (binocular fusion and depth perception).
Each patient’s potential for a good outcome is different. This fact must be well understood to avoid disappointment.
Forecast
When strabismus is congenital or develops in childhood, it can cause amblyopia, in which the brain ignores information from the deviating eye. Even with therapy for amblyopia, stereoscopic blindness can occur.
The appearance of strabismus can also be a cosmetic problem. One study reported that 85% of adult strabismus patients “reported having problems with work, school, and sports because of their strabismus.”
The same study also reported that 70% said that strabismus “had a negative effect on their self-image.” Sometimes a second operation is required to straighten the eyes.
