What is strabismus? There are several types of strabismus

Clinically, the separation of the visual axes of the eyes caused by abnormal eye position or movement is called strabismus, which is a common type. Eye diseases. Strabismus can be divided into two categories: axonal strabismus and non-apoptotic strabismus according to whether the patient has extraocular muscle dysfunction. ***Transformative strabismus, also known as ***homosexual strabismus, is a condition in which the extraocular muscles function normally and the eyeballs can move in all directions without obstruction, but the visual axes of the eyes are separated. According to the nature of the fixating eye, it can be divided into unilateral and binocular alternation; according to the time when strabismus occurs, it can be divided into intermittent, constant or periodic. Non-transformative strabismus, also known as paralytic strabismus, is a condition in which one or several extraocular muscles are paralyzed due to dysfunction of nerve conduction or the extraocular muscles themselves, resulting in separation of the visual axes of the eyes. Impairment of movement in one or more directions. After determining whether a patient with strabismus is atrophic or non-tropic strabismus, the atrophic strabismus can be divided into esotropia, exotropia and vertical strabismus according to the deflection direction of the eye position. Paralytic strabismus is named according to paralysis of nerves or dysfunction of extraocular muscles, such as oculomotor nerve palsy, superior oblique muscle paralysis, etc. Since there are many extraocular muscles that control eye movements, and there are multiple eye muscles involved in the coordinated movements of both eyes when looking at objects, the mechanism of strabismus is more complicated. To understand strabismus, we must first clarify the coordinated movement of binocular eye muscles and binocular single vision. formation mechanism.

Both human eyeballs have 6 extraocular muscles that govern eye movement. They are 4 rectus muscles and 2 oblique muscles. According to their attachment position on the eyeball, they are called medial rectus, lateral rectus, superior rectus, inferior rectus, superior oblique, and inferior oblique. Among them, the function of the internal and external rectus muscles is relatively simple, controlling the horizontal movement of the eyeball. Since the attachment points of the superior and inferior rectus muscles and the superior and inferior oblique muscles deviate from the vertical direction of the eyeball, their functions are more complex. In addition to cooperating to control the vertical movement of the eyeball, they also have the function of rotating the eyeball internally and externally, so that the eyeball can move in all directions in front of it. Ability to direct gaze. The positions and main directions of action of each eye muscle are shown in Figures 28 and 29.

Under normal circumstances, the movements of both eyes must be coordinated so that both eyes can focus on a single target at the same time. This function requires the coordinated movement of the extraocular muscles of both eyes to complete. The coordinated movement of extraocular muscles when looking at objects with both eyes is a complex muscle coordination movement. Take the horizontal movement of both eyes as an example: when looking to the right, the lateral rectus muscle of the right eye and the medial rectus muscle of the left eye contract, and at the same time, the right eye Relaxation of the medial rectus muscle and the external rectus muscle of the left eye causes the eyes to rotate to the right, and the angles of rotation should be kept equal. The superior and inferior rectus muscles and the superior and inferior oblique muscles also need to have a certain degree of tension to assist in eyeball rotation and maintain the horizontal state of the eyeballs. In this process, the pair of eye muscles (the lateral rectus muscle of the right eye and the medial rectus muscle of the left eye) that play a pulling role in the direction of eye movement are called partner muscles, while the pair of eye muscles that play a major antagonistic role with this pair of muscles (the right eye muscle) The medial rectus muscle and the left lateral rectus muscle) are called antagonist muscles. When the eyeball moves in the vertical direction, because there are multiple groups of extraocular muscles involved in the movement, there are not only partner muscles but also synergistic muscles to assist in the direction of movement. There are also direct antagonist muscles and indirect antagonistic muscles in the opposite direction, allowing synergistic movement. More complex. The partner muscles and antagonist muscles for eye movement in each direction are shown in Table 4. The coordinated movement of the extraocular muscles of both eyes follows two laws: one is that the contraction of an extraocular muscle must be accompanied by the relaxation of its direct antagonist muscle, otherwise the eyeball cannot move flexibly. This law is called Sherrington's law. The second is that the nerve impulses originating from the central nervous system to move the eyeballs must reach both eyes at the same time and in equal amounts, otherwise both eyes cannot focus on the same target. This law is called Hering's law. Because of these regularities of eye movement, the basis of human binocular vision is formed.

Binocular monovision refers to the process in which both eyes focus on a single target at the same time, so that the target is focused and imaged in the macula of both eyes, and transmitted to the visual center of the brain to overlap and become a complete and single object image with three-dimensional perception. This feature is unique to primates. During the process of biological evolution, human eyes moved forward to a position parallel to the front of the face, and most of the visual fields of the eyes overlapped, forming the basis of binocular single vision. After birth, due to interest in the surrounding environment, children often move their eyes and use gaze and re-gaze reflexes. This repeated and coordinated movement of the eyes causes the images at corresponding points on the retinas of both eyes to constantly merge into one object image in the visual center of the brain. Over time, a conditioned reflex is formed, resulting in the function of binocular single vision. Therefore, binocular monovision is gradually formed after birth. Binocular monovision function can be divided into three levels. First, both eyes can sense the same object at the same time; second, the object images sensed by both eyes can be fused into one image through the cerebral cortex; third, both eyes can see from different angles. After comprehensive analysis of the object image by the brain, a three-dimensional feeling can be obtained, and the front, rear and depth of the object can be determined, which is called stereo vision.

To sum up, due to the sophisticated perfection of the neuromuscular system in charge of eye movement, humans have the basic function of coordinated eye movement according to will. In the repeated gaze movements after birth, binocular monovision and stereoscopic vision are gradually formed. If this dysfunction of coordinating the movement of the eyes to gaze at the same target is dysfunctional, and the eyes cannot gaze at the same object at the same time, that is, the visual axes of the eyes are separated, it is called strabismus. Among them, those who are unable to form monovision in both eyes due to various reasons during the developmental stage, and whose visual axes are separated although the extraocular muscle motor function is intact, are atrophic strabismus. After the monovision function of both eyes is formed and stabilized, the monovision function that has been formed is destroyed due to neuromuscular innervation disorder, and the separation of the visual axes of both eyes accompanied by limited eye movement is a paralytic strabismus.

What are the treatments for strabismus

The causes and types of strabismus in children are different, and the treatments are also different.

(1) Different treatment methods are adopted according to the degree of strabismus: For asymptomatic phoria, no treatment is needed because children have strong fusion and convergence abilities. However, some children with phoria have short vision at close range. Symptoms of visual fatigue such as eye swelling, orbital soreness, headache, etc. can be treated appropriately. For esophoria, pupil dilation and optometry are required, and for hyperopia, appropriate glasses should be worn. For exophoria, vergence training can be done to strengthen the strength of the adductor muscles of the eyes to overcome exophoria. If the effect is not good, you can also wear prism glasses to improve your vision. For exophoria that is more than 10° (20Δ), surgical treatment may be considered.

Intermittent esotropia is mostly hyperopia. Once it is discovered, it should be dilated and refracted, and sufficient glasses for hyperopia should be worn to correct it. After wearing glasses, the intermittent esotropia can be completely corrected.

Children with intermittent exotropia should undergo strabismus and homotropia examinations to understand their binocular vision function, and undergo surgical treatment as soon as possible before the monovision function of both eyes is lost. If the single vision function of both eyes is lost, it is still possible to return to normal through surgical correction before the age of 7. If the degree of strabismus is very small, you can wear negative lenses and conduct convergence training, but this can only alleviate the symptoms and is not easy to cure.

For dominant strabismus, in addition to accommodative esotropia, early surgical treatment is often required.

(2) Different treatment methods are adopted according to different causes of strabismus: ***Congenital esotropia among homo strabismus has nothing to do with eye adjustment, but it has a great impact on the development of binocular single vision function. The best Treatment is surgical correction at the early stage of visual function development at the age of 2 years. Esotropia that occurs after 2 to 3 years of age is mostly related to excessive accommodation vergence caused by hyperopia. This kind of strabismus should be fully dilated and refracted. People with hyperopia should wear enough glasses and wear glasses for 3 to 6 months to correct or partially correct the strabismus. After correction, the remaining esotropia is surgically treated. If the esotropia does not change after wearing glasses, surgical treatment is the only option. If the strabismus is completely corrected, you can continue to wear glasses. If the degree of hyperopia is very high, you can also correct the strabismus through surgery and reduce the degree of glasses.

For patients with dominant exotropia, after excluding obvious refractive errors, the treatment principle is also early surgery. If you have poor vision, you need to fully dilate your pupils and undergo refraction. If the exotropia is caused by no adjustment, you should always wear appropriate myopia glasses. The exotropia may be corrected. If you have hyperopia combined with amblyopia, you should wear glasses according to the principle of using the lowest lens power to achieve the best corrected vision, and perform amblyopia training. If exotropia still exists, surgical treatment is required.

Children’s paralytic strabismus is mostly caused by congenital developmental abnormalities, birth trauma and illness within a few months of birth. The cause of the disease should be found first, and consultation should be conducted with otolaryngology, neurology, brain surgery, pediatrics, etc. to rule out diseases such as periorbital sinuses, cranial nerves, and intracranial tumors, accurately diagnose the primary disease, and prevent delays in treatment. In addition to treating the cause of paralytic strabismus, oral and intramuscular injections of vitamin B1, vitamin B12, inosine, coenzyme A, ATP, etc. can also be used to treat paralytic strabismus. Acupuncture and physical therapy can also be used to promote the recovery of paralyzed muscles. If the disease cannot recover after half a year of treatment, surgical treatment may be considered. However, most paralytic strabismus in children is congenital, and surgical treatment is still the main method, because congenital paralytic strabismus has little chance of forming amblyopia, and monovision function is often maintained due to compensatory head position; even if the monovision function of both eyes is incomplete or lost , as long as the operation time is early and the operation is performed appropriately, the eye position can be corrected, the compensated head position will soon disappear, and the single vision function of both eyes will be restored quickly, achieving the purpose of functional cure.

Treatment methods for amblyopia and strabismus in children

What are the treatments for amblyopia?

The treatment of amblyopia should be based on the principle of comprehensive treatment. While wearing corrective glasses, the good eye should be covered regularly, and the amblyopia should be treated with careful homework exercises of home training. Commonly used treatment methods are:

(1) Traditional covering therapy

It is divided into two types: complete covering method and alternating covering method. This is the best and most effective way to treat amblyopia. A specialist should determine an appropriate ratio based on the visual acuity of both eyes. Strictly cover the good eye and force the amblyopic eye to gaze. The more complete the covering, the faster the amblyopic eye's vision will improve.

Because the light in the healthy eye is an obstacle to improving the vision of the amblyopic eye, be sure to put the eye mask on as soon as you get up every morning until you go to bed at night. Do not take off the eye mask casually when going to school or other activities.

The complete covering method is to completely cover the healthy eye (the eye with normal vision), the more complete the better; the alternating covering method is suitable for when the vision of the amblyopic eye is close to normal, or when the vision of the amblyopic eye is similar or unequal, it can be used under regular covering. During the procedure, attention should be paid to preventing occlusive amblyopia, diplopia, strabismus, accommodation paralysis and other problems. Regular follow-up visits should be made to check the refractive status of both eyes.

(2) Suppression therapy

Use over-corrected or under-corrected lenses and daily atropine eye drops to suppress the dominant eye (suppression means using a certain lens placed in front of one eye or Use atropine eye drops to reduce the vision at a certain distance, making it change from clear to blurry). At the same time, the amblyopic eye wears corrective glasses to see far, or wears over-corrected glasses to facilitate seeing near, even if one uses the macular Gaze away from the distance, and use the macula of the other eye to gaze at the near distance, thereby promoting the function of the fovea of ??the amblyopic eye and improving the vision of the amblyopic eye.

This method is suitable for children with moderate amblyopia who are slightly older and do not want to undergo covering treatment.

The advantages are:

①Good appearance. ② Minimal damage to both eyes. ③Do not induce potential nystagmus. ④It is not easy to produce covered amblyopia.

⑤ During the treatment process, various combination therapies can be changed or utilized at any time.

Why is strabismus prone to occur in childhood?

Strabismus mainly occurs in childhood. According to statistics, about 5 out of every 100 children suffer from strabismus. Among the 300 million children in my country, about 15 million children suffer from strabismus. Even adults with strabismus mostly suffer from strabismus in childhood. The main reasons are:

(1) Imperfect development of visual function.

In children, especially infants, the visual center of the brain is not fully developed and cannot well coordinate and control the contraction and relaxation of the extraocular muscles, so their single vision function is incomplete and unstable. Any stimulation from certain external factors, such as fever, fright, trauma, etc., may weaken or lose the unstable single vision function of both eyes, inducing strabismus. The occurrence of strabismus also hinders the development of single vision function of both eyes, thereby promoting the development of strabismus and making strabismus more and more serious. The visual organs and visual functions of children before the age of 5 are not fully developed, which is the period of high incidence of strabismus.

(2) Congenital factors and birth trauma.

Congenital abnormal development of the extraocular muscles; congenital paralysis of the nerves that control the movement of the extraocular muscles; damage to the extraocular muscles and nerves of the extraocular muscles caused by maternal dystocia, all of which may lead to deviation of the eyeball position.

(3) Characteristics of children’s eyeballs.

Children have short eyeballs and have physiological hyperopia. Since children's need to see close objects gradually increases after they are 2 years old, and children's eyes have a strong ability to adjust, and their extraocular muscles contract very well, if they have the habit of looking at things too close since childhood, their eyes will always maintain a high degree of adjustment. , and it will inevitably be accompanied by excessive inward turning of both eyes, which is most likely to cause esotropia.

What measures does the treatment of strabismus include?

The purpose of strabismus treatment is mainly to restore the function of single vision in both eyes. If there is no hope of curing the visual function, plastic surgery can be performed to improve the appearance of the eyes from a purely cosmetic perspective. Commonly used strabismus treatment measures include the following:

(1) Non-surgical treatment.

①Correction of refractive errors: For strabismus caused by refractive errors such as myopia, hyperopia, and astigmatism, pupil dilation and refraction should be performed, and vision should be corrected with glasses. Many people with strabismus caused by refractive error will see a significant reduction in their strabismus after wearing glasses for a period of time. At this time, parents encourage their children to continue wearing glasses. Generally, the improvement in strabismus can be seen within about half a year. After wearing glasses, go for an optometry test every other year and adjust the prescription of your glasses in a timely manner.

②Treatment of amblyopia: A series of amblyopia treatments (such as conventional covering therapy, etc.) can be used to improve the vision of the amblyopic eye caused by strabismus, so that the two eyes can gaze alternately, thereby restoring the ability of single vision in both eyes. Function.

(2) Surgical treatment.

Children who still have strabismus after 1 to 2 years of the above non-surgical treatment should undergo eye surgery to correct the eye position on the basis of wearing glasses to prevent the occurrence and development of amblyopia, avoid head, face and Deformity of the spine.