Squint suppression

Introduction Strabismus amblyopia is caused by strabismus caused by diplopia and confusion, which makes the patient feel uncomfortable. The visual center pivotally suppresses the visual impulse of the macula from the strabismus. The eye is called strabismic amblyopia because of the long-term inhibition of the macula.

Cause

(1) Causes of the disease

The etiology of common strabismus is not yet fully understood. The factors that form common strabismus are multifaceted. For a strabismus patient, it may also be the result of several factors. The causes of the disease are different. Although each has a certain theoretical basis, there is no theory that can explain all common strabismus problems.

1. Regulating theory: The regulating effect of the eye and the collective action of the eye are related to each other, and certain adjustments bring corresponding sets. Often due to the regulation - the set reflection is too strong, the role of the inner rectus muscles beyond the tendency of the lateral rectus muscle, and the formation of common esotropia. When the nearsighted eye is close to the target, it is used less or not, and the collective force is simultaneously weakened. Therefore, the tension of the inner rectus muscle is reduced, and a common exotropia is sometimes formed. In recent years, many facts have proved that AC/A (adjustment set/adjustment, that is, the number of triangular prism diopter caused by each diopter adjustment - the triangular prism/diopter) ratio is closely related to the eye position deflection.

2, binocular reflexology: binocular single vision is a conditional reflex, is to rely on the fusion function to complete, is acquired the day after tomorrow. If the visual acuity of the two eyes is different during the formation of this conditional reflex, the visual acuity of the eye is subject to obvious sensation or movement disorder (such as monocular high refractive error, monocular refractive interstitial, fundus or optic nerve lesions, etc.), which hinders binocular monocular vision. Function, it will produce a state of separation of the eye position, that is, strabismus.

3, anatomy: a certain extraocular muscle development or hypoplasia, abnormal extraocular muscle attachment points, eyelid development, abnormal fascia structure, etc., can lead to muscle imbalance and strabismus. For example, the internal oblique may be caused by excessive development of the medial rectus muscle or dysplasia of the lateral rectus muscle or both.

4, genetic theory: clinically common in the same family, many people suffer from common strabismus. The statistics in the literature are not the same. Some reports that up to 50% of patients have a familial tendency, and there are reports that only 10% of the upper and lower, these facts make people think that strabismus may be related to genetic factors.

(two) pathogenesis

Anatomical factor

Intuitive dysplasia of the extraocular muscles, abnormal position of the extraocular muscles, abnormal muscle sheath, abnormalities of the eyeball fascia and orbital dysplasia may cause imbalance of extraocular muscle strength, which in turn leads to abnormal eye position. Because this abnormality is very slight, the muscles undergo adjustment and compensatory changes over time, and gradually appear as common strabismus. When someone measured the extraocular muscle attachment position of a patient with common strabismus, it was found that the inner rectus muscle of the esotropia patient was closer to the limbus than the inner rectus muscle of the exotropia patient. The attachment position of the lateral rectus muscle is farther away from the limbus. The greater the internal inclination, the closer the attachment position of the medial rectus muscle is to the limbus. The position of the medial rectus muscle of the patient with exotropia is far from the limbus, and the greater the angle of the external oblique, the farther the position of the medial rectus is from the limbus. It indicates that the location of the inner and outer rectus muscles is closely related to the occurrence of internal and external strabismus. Scobee's study of horizontal muscle dysplasia found that 90% of strabismus occurring before the age of 6 may have anatomic abnormalities.

2. Adjustment factors

When the object is close to the object, the lens increases the curvature, thereby enhancing the refractive power of the eye. This function is a function of changing the refractive power of both eyes to see the close target. At the same time as the adjustment is made, the eyes are turned inward to ensure that the object is imaged in the fovea of the two eyes. This phenomenon is called convergence. There is a synergistic relationship between regulation and convergence. The larger the adjustment, the larger the convergence. However, in patients with ametropia, the normal balance between the adjustment and the convulsions is lost, and the more serious the refractive error, the more unbalanced the two. Patients with hyperopia (especially moderate hyperopia), those who have been working close-up for a long time, and those with early presbyopia, because of the need to strengthen the adjustment, correspondingly produce excessive convergence, excessive convulsions may lead to esotropia. People with myopia may have insufficient convergence due to unwanted or little need for adjustment, which may lead to exotropia. Parks found that 57% of the acquired internal slant had an imbalance between the regulation and the convergence, and 59% of the external oblique had an imbalance between the regulation and the convergence.

3. Fusion function is abnormal

The fusion function is the ability of the visual center to integrate the image of the two retinas into one object image, including the two parts of perceptual fusion and kinematic fusion. Perceptual fusion is to combine the object images on the corresponding points of the two retinas, and the kinematic fusion is to re-adjust the two object images of the same object on the non-corresponding points of the two eyes to the corresponding points, thereby making the two eyes It is possible to merge two objects like one. When the object image on the retina of both eyes is separated to the temporal side, it causes convergent motion; when the object image is separated to the nasal side, it causes a separate motion. Only when the image separation in a certain range can cause fusion, beyond this range, fusion cannot be produced, that is, fusion is limited. Usually, the convergence range is 25° to 35°, and the separation range is about 4°. The fusion function is the function of the advanced vision center. When human beings are born, they do not have this function. Only after birth, in the normal visual environment, after repeated application, it gradually develops, develops and consolidates.

The fusion reflex appears about 6 months after birth, and it is getting better and more accurate around 5 years old. Fusion is an important factor in maintaining normal eye position. If the fusion function is well developed and the fusion range is large, even if the eye position is slightly skewed, it can be controlled by the fusion function without showing strabismus. On the contrary, if the fusion function is not developed properly, the slight eye position is also skewed. Will show up. Infants and young children, the fusion function is very fragile, any adverse visual environment, such as refractive error, anisometropia, long-term cover of monocular, trauma, fever, fright and genetic fusion function defects, may lead to fusion function Disorder or loss causes strabismus. Congenital strabismus is often thought to be caused by a defect in fusion function.

4. Innervation factors

When a human is in deep sleep or coma, its eye position is close to the anatomical eye position, which is an external oblique state. When awake, as long as the object is looked at, the eye position is controlled by the nervous system. If you need to see the collection, you need to set up and adjust. Only when the nerve function is normal, the eyes can keep the binocular axes parallel and consistent in any gaze direction, forming a binocular single vision.

5. Sensory disorder

Due to some factors of congenital and acquired, such as corneal opacity, congenital cataract, vitreous opacity, macular dysplasia, anisometropia, etc., the retinal imaging is unclear, vision is low, and the eyes cannot establish fusion reflection to keep the eye parallel. , which leads to strabismus. At the time of birth or early postpartum, the visual acuity is low, because the functions of regulation, convergence and fusion have not yet developed, and the external oblique is caused. In childhood, the blindness of the adjustment, convergence and fusion function is prosperous. Oblique; adult blindness, due to the regulation of diminished dysfunction, mostly lead to external oblique.

6. Genetic factors

Common strabismus has a certain familial nature, and Tianjin Eye Hospital has a family history of 6.3%. Since the same family has similar features in the anatomy and physiology of the eye, strabismus caused by anatomical abnormalities may be transmitted to the offspring in a polygenetic manner. Weardenbury reported that when one of the twins had strabismus, the other had a strabismus rate of 81.2% and a double-oval twin of 8.9%. It is also common in clinically to have monozygotic twins with strabisal properties and refractive abnormalities. Many similarities.

7. Predisposing factors

Binocular vision is a series of conditioned reflex activities that are gradually established through the normal development of the eye's tissue structure on the basis of congenital unconditioned reflexes. These reflections will take about 5 years to consolidate. If the child is disturbed by factors such as fright, high fever, brain trauma, malnutrition, etc. during visual development, it may affect the establishment of these advanced conditioning reflexes and lead to strabismus.

an examination

Related inspection

Ophthalmologic examination, eye function examination, eye examination, CT examination, fundus examination, retinoscopy

No special laboratory inspection methods.

1. General eye examination

Includes examinations for far, near vision and corrected vision as well as examination of extraocular, refractive interstitial and fundus. In order to understand whether there is amblyopia, whether there is obvious refractive error, whether there are other eye diseases caused by strabismus, with or without pseudo strabismus.

(1) Vision examination: should check far and near vision and correct vision. Children's eye exams are influenced by many factors, such as the child's age, intelligence, comprehension, presentation, mental state, and environmental conditions. In particular, infants and young children can not cooperate well, and the examination of vision is quite difficult. At present, there is no simple, accurate and reliable inspection method, so it should be checked repeatedly with patience and meticulousness. The attitude is amiable, the method is flexible and diverse, try to get the children to cooperate. In order to avoid the fear of crying in infants and young children, the examination may not be in the diagnosis room, and the child may be placed in the waiting room. Let him play with toys at will, read the picture book, observe whether there is any abnormality in the performance of the object, or use the toy and the variable brightness of the light to make a gaze target to check to attract the interest of the child and strive for the cooperation of the child.

Inspection method: Usually children over the age of 3 can be examined with an E-shaped eye chart or other letter eye chart. Training should be carried out first, and the children should cooperate for a comprehensive analysis of the results of several examinations. It is not possible to use the following results. The following methods are often used for visual inspection of infants under 3 years of age.

1 eye and head following movement: observing the ability of the baby to fix and follow the target is the main method to judge the baby's visual function. If an appropriate optotype is used, it can be confirmed that most newborns have fixation ability. The most ideal optotype is the face, especially the face of the baby's mother. The baby is lifted upright during the examination, and the examiner slowly moves his face to see if the baby moves. The movement of the baby following the target is rough. Do not turn the baby while checking, as this can cause vestibular-eye reflexes and does not indicate visual function. A 3-month-old baby can have a red spherical optotype in the front of the eye. The size of the optotype is different. When the visual target is horizontally and vertically moved within the visual field, the infant's follow-up of the visual target is used to estimate the baby's visual acuity.

2 disgusting reflex test: This test is used to judge whether there are amblyopia or binocular vision in infants and young children. During the examination, the child was seated on the mother's lap, and the cornea was illuminated with light, and the eyes were repeatedly covered alternately to observe the shaking of the head, the crying, and the change of the face. If the above situation occurs when covering one eye, it means that the visual acuity of the covering eye is good, the visual acuity of the uncovered eye is low, and the visual target is not visible.

3 squint eye gaze ability check: use the light to illuminate the cornea, if the eyes can stabilize the gaze, and the reflective point is in the center of the cornea, it means that both eyes are mostly centered, and the visual function is good. If you can't look at the light or target steadily, or even nystagmus, it means that the visual function is low.

4 optokinetic nystagmus (OKN): During the examination, a test drum (striped drum) with black and white vertical stripes is placed in front of the baby's eyes. At first, the baby's eyeball follows the movement and will be generated later. Rapid corrective reverse motion, this repeated alternating forward and reverse eye movements, forms a visual nystagmus. The stripe of the test drum is gradually narrowed, and the narrowest stripe of the optokinetic nystagmus is generated, that is, the baby's vision. The neonatal visual acuity measured by this method is 20/400, and the visual acuity of the infant in 5 months is 20/100. At present, some countries have adopted the visual tonometry method as a routine method for detecting children's vision.

5Preferential looking (PL): Since a baby's fixation is more interesting than a solid gray target stimulus, the baby looks at the two visual targets, one with black and white stripes. One is a uniform gray optotype, and the baby selectively looks at the black and white stripes. When the two optotypes appear at the same time in front of the baby, the examiner pays attention to observe the optotype that the baby is willing to watch, and replaces the stripe width until the baby is unwilling to continue observing. Up to now, the width of the stripe represents the PL vision of the baby. It can also be converted to a certain Snellen visual acuity value.

6 visual evoked potential (VEP): After the eye is stimulated by light or pattern, it can produce EEG changes in the visual cortex. After the treatment is traced, it is a visual evoked potential. VEP represents the transmission of information from the third neuron of the retina, ie, the ganglion cells. Different size of the optotype induces different potential responses. As the square shrinks and the narrowing of the grid, the VEP also changes gradually, continuously reducing the size of the optotype until VEP no longer changes, according to which can cause changes. The width of the square or grid is used to calculate the highest vision of the subject. The VEP check is superior to other children who do not speak. In the case of stable stimulation conditions, it is a more objective and accurate method of examination. But the equipment is expensive and difficult to master. The visual acuity of the baby was measured by VEP, and it was found that the progress was rapid in the first 8 weeks after birth, and the human visual acuity was 20/20 in 6-12 months.

7-point eyesight chart: This eye chart is to arrange 9 black dots of different sizes on a milky white disc for the child to identify. The eye chart is 25cm away from the eye until the child can't distinguish it. Used to check the near vision of young children.

8 Children's image chart: It is designed to be children's interest and easy to express with various patterns familiar to children.

9E word chart: The results of multiple examinations can be used to evaluate the visual function of children.

In short, the development of visual function in children will take some time to mature after birth. The visual acuity varies with age. In the same age group, vision is not the same. In general, the visual acuity gradually increases with age. It has been reported that 95% of visual acuity is 0.5 to 0.6 in 2.5 years old, 61.3% in 3 years old, and 73.6% in 4 years old, 80.4% in 5 years old, and 95.6% in 6 years old.

In China, authors used visual acuity to measure the visual acuity of 43 normal infants aged 4 to 28 weeks. The results were as follows: about 0.012 for 4-8 weeks, 0.025 for 9-12 weeks, and 0.033 for 13-16 weeks. ~20 weeks is about 0.05, and 21 to 24 weeks is about 0.1. Some people in foreign countries have measured the visual acuity of children aged 1 to 5 years. The results are: 20/200 for 1 year old, 20/40 for 2 years old, 20/30 for 3 years old, 20/25 for 4 years old, and 20/25 for 5 years old. /20.

(2) Examination of fundus and refractive interstitial: exclusion of fundus diseases and refractive interstitial opacity, such as secondary strabismus caused by poor vision caused by retinoblastoma, post-crystal fibroproliferative disease, Coats disease, etc. Clinically, many children have strabismus to the hospital for treatment. After detailed examination, it is found that there is a significant abnormal change in the posterior segment of the eye. For patients with such strabismus, the diagnosis should be confirmed first, and the primary disease should be treated. After the condition is stable, consider whether to perform strabismus surgery.

2. Examination of squint nature and squint direction: Commonly used for covering inspection. The occlusion examination method is a simple and convenient method, and the result is accurate and reliable. The nature and direction of the ocular deviation can be quickly determined, the characteristics of the ocular deviation when different gaze positions are determined, and the fixation state of the strabismus is determined. Whether there is abnormality in eye movement, determine the type and characteristics of double vision. If a prism is added, the accuracy of the strabismus can still be determined. The cover inspection has alternating eye covering and single eye covering, and the covering inspection.

(1) Alternate occlusion method: This method is a method for checking the presence or absence of occult and intermittent strabismus. When the patient is seated with the examiner during the examination, the two eyes are at the same height, and the patient is allowed to look at the light or small visual target at 33 cm or 5 m. An opaque hard plate with a width of 5 cm and a length of 10 to 15 cm was used as an eye-blocking plate, and the eyes were alternately covered, and the eyeball was rotated and rotated in the direction of removal. If the eyeball does not rotate, it means that both eyes can coordinate and gaze in the case of covering and not covering, and the eye position is not skewed. If the eyeball rotates, it means that the eye has deviated from the normal gaze position, and no longer looks at the target. When the cover is removed, the fusion function is restored, and the eye returns to the eye position. The eyeball rotates inward to be an oblique oblique, and the outward rotation is an implicit oblique, the downward rotation is an upper oblique oblique, and the upward rotation is a lower oblique oblique.

If it is not covered, both eyes are looking at the eye position. When the eye is covered, the eye position is skewed. When the cover is removed, the position cannot be restored, so that the patient can look at the close target, the fusion function of both eyes is restored, and the oblique eye is turned into a positive position, indicating that the interval is intermittent. Sexual strabismus. The basic principle of the method is to eliminate the fusion function by means of covering, so that the binocular vision becomes a single eye. During the examination, the eye mask must be quickly converted to prevent the eyes from being exposed at the same time. The covering time should be more than 2 s. Repeatedly and repeatedly destroying the fusion, and fully exposing the degree of deviation of the eye position.

(2) Monocular covering and de-covering inspection method: This method covers one eye and observes the rotation of the uncovered eye. When the covering is removed, the movement of both eyes is observed to judge the nature and direction of the strabismus.

1 In the case of binocular gaze, the eyeball does not rotate when covering any eye and removing the cover, indicating that after the fusion is destroyed, the macula gaze can be maintained, and the visual axes of both eyes are kept parallel and there is no strabismus.

2 No matter whether one eye is covered or not, the eyeball rotates in the uncovered eye, indicating that the naked eye has an eye position skew and fails to look at the target. After the gaze is covered, the naked eye is forced to change from the oblique position to the gaze position.

3 When the cover is removed, the eyes do not rotate. There may be two kinds of situations. One is the right eye and the other is the alternating strabismus. Both eyes have good vision and have gaze function. In patients with alternating strabismus, the eyes cannot At the same time, when gazing, when the eye is covered, the naked eye is gazing. When the cover is removed, the naked eye is still watching the eye position, and the original covered eye is still in the oblique position.

4 When the cover is removed, if both eyes rotate, it means that the naked eye is a constant squint eye, and the covered eye is a gaze eye, because when the eye is covered, the naked eye, that is, the constant squint eye, is forced to turn into a positive position and gaze. The target, at this time, is covered by the eye, that is, the eye is rotated and becomes a squint. However, when the cover is removed, since the eye is the eye, it immediately turns back to the positive position, and the other eye rotates, and the original oblique position is restored. Therefore, when the single eye is constantly deflected, both eyes appear to rotate when the eye is covered and uncovered.

5 When covering the cover, if the original naked eye does not move, and the cover eye rotates, it means that it is hidden, the covered eye is covered, the fusion is broken and the deflection occurs. When the cover is covered, the fusion is restored, and the covered eye turns into the eye position. .

6 Cover any eye, when the eye is covered, the eyeball rotates from top to bottom, accompanied by the rotation of the eyeball, indicating that the eyes are alternately inclined, so-called vertical eye position separation. In addition, the clinical use of the occlusion test can also distinguish the strabismus with cross-gaze is common strabismus or paralytic strabismus, to determine the nature of gaze, to diagnose intermittent strabismus. After a few hours of covering the gaze, if the abduction function is restored, it is the common internal oblique or pseudo-external paralysis of the cross-gaze. If the gaze is covered, the strabismus is still unable to turn to the right position, the corneal reflection point is not in the center of the cornea, or nystagmus occurs, indicating that the squint is a side center gaze. If the eye position is a positive position during close-up examination, after occlusion of one eye, the occultation of the covered eye will appear strabismus, and squinting after occlusion will indicate intermittent strabismus.

3. Eye movement check

Through the examination of eye movements, to understand the strength of muscle strength, whether there is obvious muscle paralysis or excessive muscle strength, and whether the movement of both eyes is consistent. When checking eye movements, check for monocular and binocular movements.

(1) Monocular exercise:

1 When the inner edge of the pupil reaches the connection point of the upper and lower punctum, the inner rotation is too strong, and the inability to reach is insufficient.

2 The outer edge of the cornea reaches the external ankle angle when the external rotation is exceeded. If the limit is exceeded, the external rotation is too strong, and those who cannot reach the outside are insufficient. It is important to note that the difference is true abduction paralysis or pseudo-external paralysis. In addition to the method of examining the abduction function after a few hours of covering the eye, the "doll head test" ( Help the child's head, so that his head is forced to suddenly turn to the opposite side, while observing whether the eye can be turned outwards, if it can be transferred to the external corner, it is a false abduction paralysis, if it can not be rotated, it is true The outreach paralysis.

3 When going up, the lower edge of the cornea reaches the inner and outer iliac line.

When the 4 is turned down, the upper edge of the cornea reaches the inner and outer iliac line.

(2) Binocular movement examination: Both eyes movement include both eyes and the two eyes. The normal movement of both eyes is coordinated under normal conditions. If there is ocular paralysis or sputum, the movement of the eyes can show different degrees of abnormality. This abnormality can be compared by comparing the amplitude of the endoscopic eye movement and the direction of the eye movement. Judging the degree of eyeball deflection when watching. When the eyes move in the same direction in one direction, the eye does not reach the proper position or the tremor-like motion (the physiological nystagmus that occurs when the eye is rotated to the extreme side under normal conditions should be excluded), indicating that the eye is in that direction. Rotating muscles are not functional. If the exercise exceeds the normal range, it means that the muscles in this direction are too strong. If the movement is in all directions, the eyeballs are equal, then they are common strabismus, otherwise they are non-common strabismus.

The coordination state of the binocular movement can also be checked by the covering method. The eye mask is used to cover one eye line of sight, and the other eye is gaze in all directions. The patient can only use one eye to look at the target, and the examiner can simultaneously observe the relative positions of the two eyes. For example, when the patient is looking to the upper right, the eye mask is placed on the right side of the patient. At this time, the patient can only focus on the target with the left eye, and then the eye mask is placed in the center of both eyes. At this time, the patient can only use the right eye. Looking at the target, if the patient has abnormalities in the extraocular muscles, this can be clearly manifested. In the two-eye co-movement, the two conjugated active muscles are called the same-directional mating muscles. There are 6 groups, namely the left intraocular rectus and the right lateral rectus muscle, the left external rectus and the right intraocular rectus, left. The right rectus muscle and the right lower eye oblique muscle, the left lower inferior rectus and the right superior oblique muscle, the right upper rectus and the left inferior oblique muscle, the right lower rectus and the left superior oblique muscle, the six pairs of the same direction The orientation of the same direction, that is, the position of the eyeball that is commonly used in clinical examination to compare and compare the muscle function of the partner, is called the diagnosis of the eye position.

The anisotropic motion includes three kinds of horizontal anisotropy, vertical anisotropy, and rotational anisotropic motion. The puppet muscle of the anisotropic movement performs the convergent movement of the rectus muscles in both eyes, the external rectus muscles of the two eyes move separately, the upper and lower rectus muscles of both eyes perform vertical movement, the upper oblique muscles of both eyes perform internal rotation, and the lower oblique muscles of both eyes perform External rotation. In daily activities, the most used anisotropic movements are horizontal anisotropic movements, and the most used convergent movements. Therefore, in the clinical examination of extraocular muscles, the examination of the function of the convergence is quite important.

Convergence is an indispensable function of anisotropic movement in binocular vision. It can be divided into two types: autonomous convergence and non-independent convergence. Non-independent convergent sputum is divided into tension convulsion, fusion convulsion, regulatory convergence and near-inductive convergence. Among them, regulatory convergence and fusion convergence are the main convergent components. Similar to the adjustment, the convergence must also maintain sufficient reserves for long-lasting work without fatigue. In order to work comfortably at close range, only 1/3 of the convections can be used frequently, and should be 1/3 of the middle of the entire range of converges. The remainder of the ends should be symmetrical. For example, at 33 cm, the patient can withstand the 4 bottom inward and 8 bottom outward prism, that is, the relative convergence is -4 ~ 8 , and the patient uses 0 ~ 4 convergence, it is comfortable.

There are three methods for measuring the convergence function:

1 Determination of the convergence near point distance method: use a small bulb as the target, so that the patient's eyes look at the bulb at the same time, the bulb should always be vertically from the front of the eye at the midpoint of the pupil line, that is, the base of the nose, and the bulb Move far and near, slowly move to the front of the patient until the maximum convergence power can not keep the eyes at the same time and look at the separation (the main light becomes two), the distance of the bulb from the base of the nose is the convergence Near point distance. Strictly speaking, the convergence near point distance should be calculated from the connection center of the two eyes, so the above distance should be added from the base of the nose to the apex of the cornea, and the distance from the apex of the cornea to the center of rotation of the eyeball. These two numbers are generally 2.5. Cm, the normal value of the near point of the convergence is 6 ~ 8cm, greater than 10cm for the lack of convergence, less than 5cm for the convergence is too strong.

Livingston Convergence Tester: This method is also a method for determining the near-point distance of the convergence, but the results are more accurate.

2 m angle measurement method: The rice angle (mA) is the distance (m) of the eyeball rotation center to the fixation point divided by the value of 1 m, that is, the rice angle (mA) = 1 / fixation distance. If the gaze distance is 1 m, the convergence value is 1 mA, and if it is 1/3 m, the convergence value is 3 mA. 1 mA is approximately equal to 3 (single eye), because 1 can shift the object image at 1 m away by 1 cm, and the normal pupil distance is 6 cm, then a 3 bottom outward prism is used in front of each eye, which produces a line of sight 6 cm, so both eyes The convergence value is 6 , and the binocular convergence value at 1/3 m is 18 .

3 Prism method: use the prism to change the line of sight angle, record the maximum bottom-out prism that can be opposed at a specified distance without generating the degree of double vision, which is the convergence force of the distance.

4. Same-view machine inspection

The synoptophore, also known as the large amplyoscope, is a large-scale multi-function optoelectronic instrument widely used in clinical practice. It is not only used to check the strabismus of different gaze directions of patients with strabismus, binocular visual function status and subjective and objective oblique angle, Kappa angle, etc. It can also be used for training of binocular vision function, treatment of amblyopia and correction of abnormal retina. Wait. The same vision machine consists of four parts: the left and right two lens barrels, the middle connection part and the base.

Each barrel includes an eyepiece, a mirror, and a picture box. The barrel can perform various movements around the horizontal, vertical and sagittal axes. That is, the upper and lower rotations are performed around the horizontal axis of the eyeball, and the inner and outer rotations are performed around the vertical axis, and the inner and outer rotational movements are performed around the sagittal axis. Regardless of whether the eyes are gazing in any direction, the same machine can perform a quantitative measurement through its moving part to check the skewness of the eye position. The lens barrel of the same camera is bent at 90°, and a plane mirror is placed at the bend, at an angle of 45° to the line of sight, so that the light of the picture passes through the mirror and becomes parallel light to reach the eyepiece, so that the patient feels that the picture is infinite from the front. At the office. Place a 7D convex spherical mirror in front of the eyepiece to place the picture on the focus of the spherical lens. The two barrels are aligned with the left and right eyes, separating the fields of view of the two eyes, the right eye is looking at the picture of the right lens barrel, the left eye is looking at the picture of the left lens tube, and the object image is projected onto the retina of the two eyes through the convex lens, and then the path of view is passed. To the center of the processing and processing.

There is a dial on the base of the same camera, engraved with the circumference and the corresponding prism. The illumination part of the same camera has three functions: changing the brightness and brightness; generating a scintillation stimulus, changing the frequency as needed, and automatically turning on and off; performing post-image treatment with glare and Haiding brush for amblyopia. The accessories of the same camera mainly include various pictures and seahead brushes. The pictures of the same vision machine are: 1 simultaneous view picture, center picture, corresponding angle of view is 1°, yellow spot picture is 3°~5°, side yellow spot picture is 10°; 2 fusion picture piece, center control picture is about 3°, yellow spot control picture is about 5°, the side yellow spot control picture is about 10°; 3 stereoscopic picture piece is used for qualitative and quantitative; 4 special picture, cross picture, Kappa angle picture.

When checking with the same machine, first adjust the position of the lower jaw and the forehead, adjust all the dial hands to 0, adjust the interpupillary distance, so that the patient's eyes are close to the eyepiece of the lens barrel, and the head position is kept straight, especially Patients with compensated head positions should pay more attention to whether their head position is correct. If there is ametropia, wear corrective glasses or a lens with the corresponding diopter in front of the eyepiece. Be patient, serious, and repeated inspections for young children to be accurate.

(1) Determination of conscious bevel: Apply simultaneous perception of the picture, which is two pictures with completely different patterns, such as lions and cages, cars and houses. The size of the picture is divided into a 10° picture that is simultaneously perceived by the macular portion, a 3° picture that is simultaneously perceived by the macula, and a 1° picture that is simultaneously perceived by the fovea. It can be selected according to different uses, patient's age, vision and intelligence. The patient is pushed by hand to push the handle of the squint side lens barrel, and the two pictures are overlapped together, and the scale indicated by the lens arm is the patient's conscious angle. If the patient repeatedly pushes the lens barrel and cannot simultaneously hold the two pictures together, it means that there is no conscious angle, indicating that the retina corresponds to the lack of. If the two pictures gradually approach each other, they suddenly jump to the opposite side, indicating that there are inhibitory dark spots nearby.

(2) Determination of the oblique angle of the squint: When checking, the ocular side lens barrel is moved to 0, the squint eye side lens arm is moved to coincide with the squint eye line of sight, and the double barrel light source is alternately turned off to observe the binocular movement. In this case, adjust the position of the lens arm until the eyeball is no longer rotated when the lamp is turned off alternately. At this time, the degree indicated on the arm of the lens tube is his oblique angle of view.

5. Binocular vision function check

Through the binocular visual function test, to understand whether the binocular visual function exists and its level, thereby providing a treatment plan, estimating the therapeutic effect and judging the prognosis. According to its complexity, binocular vision functions are divided into three levels, namely simultaneous viewing, fusion and stereoscopic viewing. The inspection method is described as follows:

(1) Simultaneous perceptual examination: Simultaneous perception refers to the ability of both eyes to simultaneously perceive objects, and is the primary binocular vision. Common inspection methods include the same camera inspection, Worth four-lamp inspection and Bagolini linear inspection.

1 Vision inspection method: As with the conscious oblique angle view, the application can simultaneously perceive the picture, the patient can simultaneously perceive the two pictures, and can overlap the two pictures together, that is, the simultaneous viewing function. If only one picture can be perceived and the other picture cannot be perceived, it is monocular suppression and has no simultaneous view function. Although both eyes can simultaneously sense the presence of two pictures, in any case, the two pictures cannot be overlapped together, and there is no simultaneous viewing function.

2Worth four-point light inspection method: This method is designed according to the principle of complementary red and green colors. The Worth four-point light is composed of a green light on each side, a red light on the top, a white light on the bottom, and a diamond arrangement on the 4th. The inspectors wear red and green complementary glasses, such as red lenses on the right eye and green lenses on the left eye. Because the red and green are complementary, the red-light lens can only see the red and white lights, and the green light is not visible. The green-light lens can only see the green and white lights, and the red light is not visible. Through this kind of inspection, the following can occur: A. Only see 2 red lights, for left eye suppression; B. Only 3 green lights, for right eye suppression; C. Red light, green light alternate but not simultaneously aware, For alternate suppression. In the above cases, there is no simultaneous viewing function; D. Seeing 5 lights at the same time, that is, 2 red lights and 3 green lights, indicating that there is a hidden or oblique, but no suppression, the red light is on the right, and the green light is on the left. Internal oblique, if the red light is on the left, the green light is on the right, the outer is oblique, there is an abnormal simultaneous view (double vision); E. If you can see 4 lights, the top is red, the two sides are green, the bottom is The red light (the right eye is the dominant eye) or the green light (the left eye is the dominant eye) is a positive eye and has a simultaneous viewing function.

Worth four-point lamp is simple in structure and convenient to check. It can quickly and accurately check the state of binocular gaze. It is feasible to measure far and close distance. The distance is 5m, the projection angle is 2°, and the central part is swallowed. The close-up inspection is 33cm. The projection angle is 6°, and the peripheral fusion function is checked. If there is ametropia, you should wear a mirror.

3Bagolini linear microscopy: This method is a simple and valuable method, especially for judging whether there is abnormal retinal correspondence, simultaneous vision, fusion function and rotational strabismus. The linear mirror is engraved with a number of extremely thin oblique parallel lines. The lines of the two eyes are perpendicular to each other. If the direction of the line on the right lens is 45°, the direction of the line on the left lens is 135°. When looking at the light, the light is regarded as a linear light perpendicular to the direction of the line on the lens, that is, the right eye is linear light in the 135° direction, and the left eye is linear light in the 45° direction. During the examination, the patient looks at the light at 33cm or 5m, and according to the results seen by the patient, understands the binocular visual function status:

A. Can see 2 linear lights, intact, vertical cross, point intersection at the point source, the fusion function is good, if the patient has oblique presence, it is abnormal retina corresponding;

B. If the linear light is defective, it indicates that the fovea has an inhibitory dark spot, and the larger the defect, the larger the inhibition range, but there is peripheral fusion;

C. Only one linear light is seen, indicating monocular inhibition, no simultaneous visual function, two linear light alternately appear, which is an alternate inhibition of both eyes, seen in alternating strabismus;

D. If the two linear lights intersect vertically, but the point source is not at the intersection, it is a strabismus double vision. The two spots are above the intersection and the external oblique double vision. The two spots are below the intersection. The inner oblique is the same side double vision, the two light points are on the upper left and the lower side of the intersection, and the left eye is squint double vision. The two light spots are on the upper side and the lower side of the intersection point, and the right eye is upper strabismus double vision. If the two linear lights do not cross vertically, it is a rotating double vision. When the upper and lower apex angles are acute, the internal rotation is double vision, the upper and lower apex angles are obtuse angles, and when the horizontal apex angle is acute, the external rotation is double vision.

4 Bar reading test: Place your finger or pen between the eye and the book while reading, keep the position of the head, fingers and books unchanged. If you have eyes, you can read it smoothly. If you find text on the book, If it is occluded and cannot be read smoothly, it means that it is monocular and has no fusion function. If the positions of the occluded characters alternately change, it is alternately gazing. The method is easy to check and does not require special equipment.

5 palm ring test: a 25 cm thick paper is rolled into a cylinder of 2 to 3 cm in diameter, placed in front of one eye (such as in front of the right eye), and the right eye looks at a target (five stars) through the paper tube, left The palm is flat, placed close to the center of the paper tube, the left eye is looking at the palm of the hand, and there are eyes with a double eye. You can see that there is a circle in the center of the palm, and there are five stars in the circle with the right eye. If it is a single eye, only the circle or palm can be seen.

(2) Fusion function check method: The fusion function is a higher level of visual function than simultaneous view, and plays a very important role in maintaining the positive position of both eyes. If the fusion function is strong, that is, the fusion range is large, it is very advantageous for the correction of strabismus and the restoration of binocular single vision. If the fusion range is extremely small, the strabismus correction is prone to fusion incompetence and diplopia. Extremely difficult to disappear. Therefore, if the patient is weak, surgery should be considered a contraindication. For the determination of the fusion function, the commonly used methods are the homophone method and the prism method.

1 Same vision inspection method: use the fusion picture to check. This kind of picture is two pictures that are similar but not identical, and the different parts are control points. The fusion picture is divided into three parts: the peripheral part, the macula and the fovea. Large pictures are easy to merge. When inspecting, insert the pictures into the lens barrels on both sides of the same camera, and let the patient push the arm until the patterns on both sides are completely recombined into a complete pattern. The angle is the fusion point, then The self-convergence point is outward (indicated by a negative sign) and inward (indicated by a positive sign) to push the barrel until it can no longer be fused, which is the fusion range. The normal horizontal fusion range is -4° to 30°, and the vertical fusion range is 1° to 2°.

2 Prism measurement method: When the patient is inspected, the patient will look at the light at 33cm or 5m, and check the fusion ability at the far and close distances respectively. Adding a prism to the outside in front of one eye, gradually increasing the degree of the prism, and the prism power when the light is double-shadowed is its convergence force. Then add the inward-facing prism to the front of the eye, and the prism power when the light is double-shadowed is the split fusion force. The vertical fusion force is also measured by adding a prism up or down to the front of the eye.

(3) Stereoscopic inspection: Stereoscopic vision is the highest level of binocular vision. It is the visual function of the size of the space object, the front and back distance, the convex and concave, and the near and far. Stereoscopic vision is divided into peripheral stereoscopic view and central stereoscopic view. The formation of stereoscopic vision is due to the presence of binocular parallax, especially the presence of horizontal parallax between binocular retinal images. The minimum parallax that the human eye can discern is called stereoscopic sharpness, and the stereoscopic sharpness can be expressed by the parallax angle (generally the second arc). The stereoscopic sharpness of a normal person is 5 to 10. However, the normal stereoscopic sharpness that can be detected clinically is equal to or less than 60". The commonly used inspection methods for stereoscopic vision are as follows:

1 Howard-Dolman deep sensation check: The deep sensation meter is equipped with two vertical rods, the two rods are horizontally spaced 64mm apart, one rod is fixed, one rod can be pulled by the rope, moving back and forth, and the depth sensation is placed at 6m. Let the patient observe the position of the two poles through the peephole, and pull the rope to level the two poles. The examiner observes whether the patient has actually leveled the two poles, records the number of millimeters of the two poles, and measures three times, taking the average value, according to the difference of millimeters. Number, calculate the parallax angle. The calculation formula is: a=bd/S2 (a is the parallax angle, b is the pupil distance, the normal is 60 mm, d is the number of millimeters of the difference between the two rods, the normal should be less than 30 mm, S is the inspection distance, generally 6000 mm), The result calculated by this formula is radians. Since 1 radians is equal to 57.2958°, if it is converted into seconds, it should be 206265 (ie 57.2958×60×60), and the resulting parallax angle a=60×30×206 265/60002=10.3133, normally should be less than 10.3, ie two shots The average difference distance should be less than 30 mm.

2 Same-view machine inspection method: The stereoscopic picture is used for inspection. The stereoscopic picture is a pair of very similar pictures, such as a bucket picture. The outer circles of the two pictures are exactly the same, but the positions of the two inner circles are slightly different. The inner circle of one picture is offset to the right, and the inner circle on one picture is shifted to the left, and the distance of the skew is equal. The two pictures are placed in the lens barrels on both sides of the same camera. When the outer circles are overlapped, the inner circle is perceived by the non-corresponding points of the eyes, and merges into a bucket with a three-dimensional feeling. Stereoscopic quantitative examination can be performed if a random point stereo picture is used.

3Titmus stereoscopic inspection chart: used to check close-up stereo vision. The inspection distance is 40cm, and the examinee wears polarized glasses, so that the eyes of the two eyes are slightly separated, and the pattern on the inspection chart is observed. The fly pattern is used for qualitative examination, and the others are used for quantitative examination. If there is a stereoscopic view, the flies will obviously float on the reference surface, and those without stereopsis will not feel this. When measuring the stereoscopic sharpness, the patient looks at each group of circle patterns, each group has 4 circles, and one circle is different from the rest. It is easy to recognize the stereoscopic viewers, and the parallax angles of the original design according to the pattern of each group number are different, that is, The threshold value can be measured, and the parallax of pattern No. 1 is 800. The larger the number, the smaller the parallax angle. The parallax of patterns 7, 8, and 9 are 60, 50 and 40, respectively, and can recognize 1 to 6 When the pattern is displayed, it indicates that there is a peripheral stereoscopic view, and when the pattern No. 7 to No. 9 can be recognized, it indicates that there is a central stereoscopic view.

4 Random point stereogram: This figure was developed by China's Yan Shaoming and Zheng Yuying, and is also designed according to the principle of parallax. Matching the two shapes and sizes exactly the same as the random point distribution is cleverly concealed in the same two textures, except that one figure is slightly staggered in the horizontal direction compared to the other, causing a slight binocular parallax between the two figures.

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Differential diagnosis

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(2)

(esotropia)

(exotropia)

(hypersropia)

(hypotropia)

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