Strabismus , also known as cross-eye , is a condition in which the eyes are not aligned with each other when viewing objects. Eyes that focus on the object can alternate. This condition can be present occasionally or continuously. If present during most of childhood, it can cause amblyopia or loss of depth perception. If onset occurs as an adult, it is likely to produce double vision.
Strabismus can occur due to muscle dysfunction, farsightedness, problems in the brain, trauma, or infection. Risk factors include premature birth, cerebral palsy, and a family history of the condition. Types include esotropia in which the eye is crossed; exotropia in which the eye deviates; and hypertropia where they are vertically aligned. They can also be classified by whether the problem is present in any direction a person is seen (commit) or varies by direction (unwarranted). Diagnosis can be done by observing the light that bounces from the person's eyes and finds that it is not centered on the pupil. Another condition that produces similar symptoms is cranial nerve disease.
Treatment depends on the type of strabismus and the underlying cause. This may include the use of glasses and possibly surgery. Some types of benefits from the initial operation. Strabismus occurs in about 2% of children. The term comes from the Greek strabismÃÆ'³s which means "squint". Other terms for conditions include "squint" and "eyeballs". "Wall-eye" has been used when the eyes are turned away from each other.
Video Strabismus
Signs and symptoms
When looking at someone with strabismus, the misalignment of the eye may be quite obvious. A patient with significant constant eye turns is very easy to notice. However, small or intermittent strabismus can be easily missed on ordinary observations. However, an eye care professional can perform various tests, such as closing tests, to fully determine strabismus.
Symptoms of strabismus include double vision and/or eye strain. To avoid double vision, the brain can adapt by ignoring one eye. In this case, there are often no visible symptoms other than the loss of small depth perception. This deficit may not be seen in someone who has been born or early childhood strabismus, as they may learn to assess the depth and distance using monocular cues. However, the constant unilateral strabismus that causes constant suppression is the risk of amblyopia in children. Small and intermittent angular strabismus is more likely to cause disturbing visual symptoms. In addition to headaches and eye strain, symptoms may include an inability to read comfortably, reading tiredness, and unstable or "restless" vision.
People of all ages who have visible strabismus may experience psychosocial difficulties. Attention has also been drawn to the potential socioeconomic impact resulting from the case of detectable strabismus. Socioeconomic considerations exist also in the context of decisions regarding the treatment of strabismus, including efforts to rebuild binocular vision and possible stereopsis recovery.
One study has shown that strabismic children generally exhibit behaviors characterized by higher levels of inhibition, anxiety, and emotional distress, often leading to direct emotional disturbance. This disorder is often associated with negative perceptions of children by peers. This is due not only to the changing aesthetic appearance, but also to the symbolic attributes attached to the eyes and views, and the crucial role that they play in the lives of individuals as a social component. For some, this problem increases dramatically after strabismus surgery. In particular, strabismus disrupts normal eye contact, often causing shame, anger, and awkward feeling, thus affecting basic social communication, with the possibility of a negative effect on self-esteem.
Children with strabismus, especially those with exotropia (outward changes), may be more likely to develop mental health disorders than normal-looking children. Researchers have theorized that esotropia was not found to be associated with a higher tendency for mental illness due to the age range of participants, as well as shorter follow-up periods; esotropic children were monitored with an average age of 15.8 years, compared with 20.3 years for the exotropic group. A subsequent study with participants from the same area monitored congenital esotropic patients for longer periods of time; The results showed that esotropic patients were also more likely to develop mental illness of some kind after reaching early adulthood, similar to those with constant exotropia, intermittent interotropia, or convergence insufficiency. Chances are 2.6 times that of control. There is no clear association with preterm births observed, and no evidence has been found that links the onset of mental illness to the psychosocial stressors often encountered by those with strabismus.
Investigations have highlighted the possible impact of strabismus on quality of life. Studies in which subjects are shown images of strabismic and non-strabismic people show a strong negative bias against those who are seen displaying the conditions, clearly indicating potential for future socioeconomic implications with regard to employability, as well as other psychosocial effects associated with the overall individual. happiness.
Adult and child observers consider right heterotropia more disturbing than left heterotropia, and child observers regard esotropia as "worse" than exotropia. Successful surgical correction of strabismus - for both adult and adult patients - has been shown to have a significant positive effect on psychological well-being.
Very little research on coping strategies used by adult strabism. One study categorized coping methods into three subcategories: avoidance (refrain from participation of an activity), disturbance (divert attention from conditions), and adjustment (approaching an activity differently). The study authors suggest that individuals with strabismus may benefit from psychosocial support such as interpersonal skills training.
No study has evaluated whether psychosocial interventions have benefits in individuals undergoing strabismus surgery.
Maps Strabismus
Cause
Strabismus can be seen in Down syndrome, Loeys-Dietz syndrome, cerebral palsy, and Edwards syndrome. The risk increases among those who have a family history of the condition.
Pathophysiology
Extraocular muscles control the position of the eye. Thus, problems with muscles or nerves that control them can cause paralytic strabismus. The extraocular muscles are controlled by the III, IV, and VI cranial nerves. A cranial nerve damage III causes the associated eye to deviate downwards and may affect the size of the pupil. IV cranial nerve disorder, which can be congenital, causes the eye to drift and may be slightly inward. Sixth nerve palsy causes the eye to deviate inward and has many causes because of relatively long nerve pathways. Increased cranial pressure can compress the nerves as they travel between the clivus and the brainstem. Also, if the doctor is not careful, twisting the baby's neck during delivery delivery can damage the cranial nerve VI.
The evidence suggests the cause of strabismus may lie in the input given to the visual cortex. This allows strabismus to occur without direct interruption of any 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 signals coming from the eye through a process called visual development. Development can be disrupted by strabismus if the child is always fixed with one eye and rarely or never fixated with the other. To avoid double vision, the signal from the deviated eye is suppressed, and the constant emphasis on one eye causes a failure of visual development in that eye.
Also, amblyopia may cause strabismus. If the big difference in clarity occurs between images of the right and left eyes, the input may not be enough to reposition the eyes properly. Other causes of visual differences between the right and left eyes, such as asymmetric cataracts, bias errors, or other eye diseases, can also cause or worsen the strabismus.
Accommodative Esotropia is a form of strabismus caused by refractive errors in one or both eyes. Since it is almost triassic, when a patient does accommodation to focus on a close object, an increase in the signal sent by the cranial nerve III to the medial rectus muscle results, draws the eye inward; This is called Reflex Accommodation. If accommodation needs are more than the usual amount, such as with people with significant hyperopia, additional convergence can cause the eye to cross.
Diagnosis
During an eye exam, tests such as closing tests or Hirschberg tests are used in the diagnosis and measurement of strabismus and its effect on vision. Retinal birefringence scanning can be used for screening children for eye misaligment.
Some classifications are made when diagnosing strabismus.
Latency
Strabismus may manifest ( -tropia ) or latent ( -foria ). The real deviation, or heterotropia (which may be eso - , exo - , hyper - , hypo - , cyclotropia or a combination of these), present when the patient sees the target binoculars, without occlusion of both eyes. Patients can not align the gaze of each eye to achieve fusion. Latent deviation, or heterophoria ( eso - , exo - , hyper - , hypo - , cyclophoria or a combination of the two), only present after the binocular vision is disturbed, usually by closing one eye. This type of patient usually can maintain fusion despite the misalignment that occurs when the positioning system is relaxed. Intermittent strabismus is a combination of these two types, in which the patient can reach fusion, but occasionally or often intermittently to the point of real deviation.
Onset
Strabismus can also be classified by time of onset, either congenital, obtained, or secondary to other pathological processes. Many babies are born with their eyes slightly parallel, and this is usually drought at the age of six to 12 months. The acquired and secondary strabismus develops later. The onset of esotropia is accommodative, overconvergence of the eyes due to accommodation efforts, mostly in early childhood. Acquired non-accommodating strabismus and secondary strabismus are developed after normal binocular vision has been developed. In adults with previous normal alignment, the onset of strabismus usually results in double vision.
Any disease that causes vision loss can also cause strabismus, but can also be caused by severe and/or traumatic injury to the affected eye. Sensory strabismus is strabismus due to loss of vision or disorder, leading to horizontal, vertical or torsional misalignment or to a combination of both, with eyes with worse eyesight drifting slightly over time. Most often, the result is a horizontal misalignment. The direction depends on the age of the patient where the damage occurs: patients whose vision is lost or disturbed at birth are more likely to develop esotropia, whereas patients with lost vision acquired or disorder develop most of the exotropia. In the extreme, total blindness in one eye generally leads to a blind eye that returns to an anatomical position of rest.
Although many possible causes of strabismus are known, including severe and/or traumatic injury to the affected eye, in many cases no specific cause can be identified. The latter usually occurs when strabismus is present from an early childhood.
The results of a US cohort study show that the incidence of adult onset strabismus increases with age, especially after the sixth decade of life, and the peak in the eighth decade of life, and that the lifetime risk of being diagnosed with adult onset strabismus is about 4%.
Laterality
Strabismus can be classified as unilateral if one eye consistently diverges, or alternately if one of the eyes can look distorted. Alternating strabismus can occur spontaneously, with or without subjective consciousness of the turn. Alternatives can also be triggered by various tests during an eye exam. Unilateral strabismus has been observed due to severe or traumatic injury to the affected eye.
Directions
Horizontal aberrations are classified into two varieties. Eso describes the deviation into or converges toward the midline. Exo describes outgoing or different misalignment. Vertical aberrations are also classified into two varieties. Hyper is a term for eyes whose gaze is directed higher than peer eyes when hypo refers to an eye with a lower directed gaze. Cyclo refers to torsional strabismus, which occurs when the eyes rotate around the anterior-posterior axis to be uneven and quite rare.
Naming
Directional prefixes are combined with -tropia and -foria to describe different types of strabismus. For example, constant left hypertrophy exists when the patient's left eye is always directed higher than the right. A patient with intermittent right esotropia has a right eye that sometimes drifts toward the patient's nose, but at other times is able to align with the left eye view. A patient with mild ecoforia can maintain fusion during normal circumstances, but when the system is compromised, the posture relaxes slightly differently.
Other considerations
Strabismus may be further classified as follows:
- Paretic strabismus is caused by the paralysis of one or more extraocular muscles.
- Nonparetic strabismus is not due to extraocular muscle paralysis.
- Commitant (or concurrent ) strabismus is an equally large deviation regardless of position of view.
- Non-prolonged (or haphazard) strabismus has varying magnitudes as the patient shifts his or her view up, down, or sideways.
Nonparetic strabismus is common at the same time. Most types of infant strabismus and childhood are commitent. Paretic strabismus may be either a commitment or a noncomitant. Incomitant strabismus is almost always caused by the limitations of ocular rotation caused by restriction of extraocular eye movement (ocular restriction) or due to extraocular muscle paresis. Incomitan strabismus can not be completely corrected by prism sunglasses, since the eye will require different degrees of prismatic correction depending on the direction of sight. Incomitant strabismus from eso- or exo-type is classified as "alphabetical pattern": they are denoted as A- or V- or more rarely? -, Y- or X-patterns depending on the extent of the convergence or divergence when the view moves up or down. The letters of this alphabet show an ocular motility pattern that has similarities to each letter: in A-pattern there is (relatively speaking) more convergence when the view is directed upwards and more of the difference when directed downwards, in V- the pattern is the opposite, in the pattern? -, Y, and X there is little or no strabismus in the middle position but relatively more deviations in one or both positions up and down, depending on the "shape" of the letter.
Incomitan strabismus types include: Duane syndrome, horizontal gaze view, and congenital extraocular muscular fibrosis.
When the eye misalignment is large and clear, strabismus is called a large angle, referring to the angle of deviation between the sight lines of the eye. Less severe eye rotation is called small angular strabismus. The level of strabismus may vary based on whether the patient sees distant or near targets.
Strabismus that arises after eye coating has been surgically corrected called strabismus successively .
Comparative diagnosis
Pseudostrabismus is the wrong appearance of strabismus. Usually occurs in infants and toddlers whose bridge of the nose is wide and flat, causing the appearance of esotropia due to a less visible sclera nasally. As we get older, the child's nose bridge narrows and the creases in the corner of the eye become less prominent.
Retinoblastoma can also produce abnormal reflections of light from the eyes.
Management
Like other binocular vision disorders, the main purpose is comfortable, single, clear, normal binocular vision at all the distance and direction of sight.
Strabismus is usually treated with a combination of glasses, vision therapy, and surgery, depending on the underlying reason for the misalignment.
While amblyopia, if minor and detected early, can often be corrected by using a blindfold on dominant eyes and/or vision therapy, the use of an eye patch is unlikely to alter the angle of strabismus.
Glasses
In accomodative esotropic cases, the eye changes inward because of the effort to focus the distant eye, and this type of strabismus treatment necessarily involves refractive correction, usually done through corrective sunglasses or contact lenses, and in this case surgical alignment is only considered if the correction did not complete the bend of the eye.
In the case of strong anisometropia, contact lenses may be better than glasses because they avoid the problem of visual differences due to size differences (aniseikonia) which if not caused by glasses in which the bias strength is very different for both eyes. In some cases of strabismic children with anisometropic amblyopia, refractive refractive eye balance through refractive surgery has been performed before strabismus surgery is performed.
Early treatment of strabismus when the person is an infant may reduce the likelihood of developing amblyopia and depth perception problems. However, a review of randomized controlled trials concluded that the use of corrective goggles to prevent strabismus was not supported by existing studies. Most children eventually recover from amblyopia if they benefit from patches and corrective sunglasses. Amblyopia has long been considered permanent if not treated in a critical period, ie before the age of about seven years; However, recent findings provide an excuse to challenge this view and to align previous ideas from a critical period to account for stereopsis recovery in adults.
Eyes that remain uneven can still develop visual problems. Although not a cure for strabismus, prism lenses can also be used to provide temporary comfort and prevent double vision.
Surgery
Strabismus surgery does not eliminate a child's need to wear glasses. At present it is not known whether there is a difference to complete strabismus surgery before or after amblyopia therapy in children.
Strabismus surgery seeks to align the eye by shortening, lengthening, or altering the position of one or more extraocular eye muscles. This procedure can usually take about an hour, and takes about six to eight weeks for recovery. Adjustable sutures can be used to allow the improvement of eye alignment in the early postoperative period.
Double vision can rarely occur, especially immediately after surgery, and loss of vision is very rare. Glasses affect position by changing the person's reaction to focus. Prisms change the light of the road, and therefore the image, attack the eye, imitate the change in eye position.
Drugs
Drugs are used for strabismus under certain circumstances. In 1989, the US FDA approved Botulinum toxin therapy for strabismus in patients older than 12 years. Most commonly used in adults, this technique is also used to treat children, especially children affected by infantile esotropia. Toxins are injected into stronger muscles, causing temporary and partial paralysis. Treatment may need to be repeated three to four months later after paralysis disappears. Common side effects are double vision, eyelid drooping, excessive correction, and no effect. Side effects usually disappear within three to four months. Botulinum toxin therapy has been reported as successful as strabismus surgery for people with binocular vision and less successful than surgery for those with no binocular vision.
Prognosis
When the strabismus is congenital or develops in infancy, strabismus can cause amblyopia, in which the brain ignores the input of the deviant eye. Even with therapy for amblyopia, stereoblindness can occur. The appearance of strabismus can also be a cosmetic problem. One study reported 85% of adult strabismus patients "reported that they had problems with work, school, and sports because of their strabismus." The same study also reported 70% said strabismus "has a negative effect on their self-image." A second operation is sometimes needed to straighten the eyes.
References
Further reading
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Donahue, Sean P.; Buckley, Edward G.; Christiansen, Stephen P.; Cruz, Oscar A.; Dagi, Linda R. (August 2014). "The difficult problem: strabismus". Journal of the American Association for Pediatric Ophthalmology and Strabismus (JAAPOS) . 18 (4): e41. doi: 10.1016/j.jaapos.2014.07.132. Ã,
External links
- Media related to Strabismus in Wikimedia Commons
Source of the article : Wikipedia
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