Squint

Introduction to strabismus Strabismus refers to the fact that both eyes cannot simultaneously focus on the target, which is an extraocular muscle disease. Can be divided into two types of common strabismus and paralytic strabismus. The former has an eye position biased to the temporal side, the eyeball has no movement disorder, and no recurrence is regarded as the main clinical feature; paralytic strabismus has limited eye movement, diplopia, and accompanied by systemic symptoms such as dizziness, nausea, and gait instability. The etiology of strabismus is complicated. Modern western medicine has no ideal method for the cause and surgical treatment. basic knowledge The proportion of sickness: 0.01--0.03% Susceptible people: more common in young children Mode of infection: non-infectious Complications: Amblyopia

Cause of strabismus

The etiology of strabismus is complicated. Modern western medicine has no ideal method for the cause and surgical treatment.

Pathogenesis:

Clinically, the separation of binocular visual acuity caused by abnormal eye position or movement is called strabismus, which is a relatively common type of ophthalmic disease. Strabismus can be divided into two categories: co-rotating strabismus and non-co-rotating strabismus according to whether the patient has extraocular muscle dysfunction. Co-rotating strabismus, also known as common strabismus, is normal for each extraocular muscle function, and the eyeball moves in all directions without barriers but the eyes are separated. According to the nature of the gaze, it can be divided into unilateral and binocular alternation; the time according to strabismus can be divided into intermittent, constant or periodic. Non-co-transitive strabismus, also known as paralytic strabismus, is one or several extraocular muscle paralysis caused by nerve conduction or extraocular muscle dysfunction, and the eyes are separated by visual axis. The eye is paralyzed by eye muscles. One or more movement obstacles. After confirming that the strabismus patients are co-rotating or non-co-rotating strabismus, the co-rotating strabismus can be divided into esotropia, exotropia and vertical strabismus according to the oblique direction of the eye position. Paralytic strabismus is named after the paralyzed nerve or dysfunctional extraocular muscles, such as oculomotor nerve palsy and superior oblique palsy. Because there are many extraocular muscles that control the eye movement, and there are multiple eye muscles involved in the coordinated movement of the eyes, the mechanism of strabismus is complicated. To understand strabismus, we must first clear the synergy of the eye muscles and the binocular single vision. Form a mechanism.

Each of the two human eyeballs has six extraocular muscles that dominate the eye movements. They are four rectus muscles and two oblique muscles. According to their attachment positions on the eyeball, they are called the medial rectus, lateral rectus, superior rectus, inferior rectus, and superior oblique and inferior oblique muscles. The role of the internal and external rectus muscles is relatively simple, and it plays a role in controlling the horizontal movement of the eyeball. The attachment points of the superior and inferior rectus muscles and the superior and inferior oblique muscles are more complicated due to the deviation from the vertical direction of the eyeball. In addition to the vertical movement of the eyeball in coordination, the function of rotating the movement inside and outside the eyeball is also performed, so that the eyeballs are in front of each other. Can be directed.

Under normal circumstances, the binocular movements must be coordinated so that both eyes can simultaneously focus on a single target. This function requires the coordinated movement of the extraocular muscles of both eyes to complete. The coordinated movement of the extraocular muscles during binocular vision is a complex muscle coordinated movement. Take the horizontal movement of both eyes as an example: when looking to the right, the right lateral rectus muscle and the left intraocular rectus muscle contract, while the right eye The inner rectus muscle and the left lateral rectus muscle relax and rotate the eyes to the right, and their rotation angles should be equal. The upper and lower rectus muscles and the superior and inferior oblique muscles also have a certain degree of tension to assist the eyeball to rotate and maintain the level of the eyeball. In this process, a pair of eye muscles (right rectus and left rectus) in the direction of eye movement are called the mating muscles, and a pair of eye muscles (right eye) that play a major role in opposing the muscles. The medial rectus and the left lateral rectus muscle are called antagonistic muscles. When the eyeball moves in the vertical direction, because there are multiple groups of extraocular muscles involved in exercise, there are not only the partner muscles, but also the synergistic muscles to assist the movement direction. In the opposite direction, there are also direct antagonist muscles and indirect antagonist muscles. More complicated.

The joint movement of the extraocular muscles of both eyes follows two rules: one is that the contraction of an extraocular muscle must be accompanied by its direct anti-muscle relaxation, otherwise the eyeball cannot be flexibly rotated. This law is called Sherrington's law. The second is the nerve impulse that causes the eyeball to rotate from the central nervous system. It must reach both eyes at the same time and equal amount. Otherwise, the eyes cannot look at the same target. This law is called Hering's law. Due to these regularities of eye movements, the basis of human eyes' single vision is formed.

Binocular single vision refers to the process in which both eyes are simultaneously focused on a single target, so that the target is focused on the macular of both eyes, and transmitted to the brain visual center to form a complete and stereoscopic single object. This function is unique to primates. In the process of biological evolution, the human eyes move forward to the parallel position in front of the face, and the eyes of both eyes overlap mostly, which has the basis of binocular single vision. After birth, due to the interest in the surrounding environment, the eyeball is often turned, and the gaze and re-reflection are used. This repeated coordinated binocular movement causes the images on the corresponding points of the retina of the eyes to constantly merge into an object image in the center of the brain, forming a conditioned reflex for a long time, producing a binocular single vision function. Therefore, binocular single vision is gradually formed after birth. The binocular single vision function can be divided into 3 levels. First, the eyes can feel the same thing at the same time.

Strabismus prevention

According to clinical observations, the main eye disease that causes children to have strabismus when watching TV is monocular squint, that is, the gaze is fixed on one side. Because of the disparity in vision between the two eyes, it often uses eyesight with better vision and poor eyesight. The eyes are slanted.

Prevention points :

1. Prevention of strabismus should be taken from infants and young children, parents should pay attention to carefully observe the child's eye development and changes.

2. Infants and young children should strengthen nursing during fever, rash, and weaning, and often pay attention to the coordination function of both eyes to observe whether there is abnormality in the eye position.

3. Always pay attention to your child's eye hygiene or eye hygiene. If the lighting is appropriate, it should not be too strong or too weak. The printed picture should be clear. Don't lie down and read the book. Don't watch TV and play games and computers for a long time, don't look at 3D pictures.

4. For children with a family history of strabismus, although there is no strabismus in appearance, please check with an ophthalmologist at 2 years of age to see if there is hyperopia or astigmatism.

5. When children watch TV, besides paying attention to a certain distance, children should not be allowed to sit in the same position every time, especially the position of the TV. Should always exchange seats in the left, center, right, otherwise the child in order to watch TV, the eyeballs look in one direction, the head will habitually squat to one side. After a long time, the development and tension of the six eye muscles are different, losing the original balance of regulation, one side of the muscle is always in a state of tension, the other side is slack, it will cause strabismus.

Strabismus complications Complications amblyopia

Most patients with strabismus have amblyopia at the same time. Because the strabismus patient has long-term one eye gaze, the other eye will cause disuse of vision loss or stop development, and even after wearing appropriate glasses, vision will not reach normal.

In children, strabismus also affects the development of the whole body's bones, such as the compensatory head position of congenital paralysis strabismus, which causes neck muscle contracture and pathological curvature of the spine, and facial asymmetry.

Strabismus symptoms Common symptoms Internal oblique V sign XV- phenomenon oblique eye inhibition eye fatigue XA- phenomenon external oblique A sign vision often foggy blur

Children with mild internal and external strabismus will not cause eye discomfort. If the inclination is high, there will be eye discomfort. Vertical strabismus has obvious eye discomfort. Rotational strabismus causes obvious symptoms of eye and general discomfort. The symptoms of strabismus are also related to factors such as general health and mental state.

The following symptoms often occur in strabismus :

1. After a long time, there are often headaches, eye aches, and photophobia. This is caused by the continued use of the neuromuscular reserve to cause eye muscle fatigue.

2. When reading, there are illegible or overlapping, overlapping, serial, sometimes intermittent diplopia, intermittent strabismus, if you use a single eye to see it is clear, labor-saving, and even binocular vision disorder.

3. The stereoscopic feeling is poor, and the position and distance of the space object cannot be accurately determined. Concealed strabismus can also have neurological symptoms such as nausea, vomiting, insomnia, conjunctiva and blepharospasm.

Strabismus examination

The eyes of a strabismus patient cannot simultaneously focus on the target. The following is a routine inspection of strabismus:

(1) Inspection of binocular visual function: 1 The third-level situation in which the same visual machine is used in the country to check the binocular vision function. 2 Quantitative measurement of stereoscopic function, stereoscopic visual acuity is determined by stereoscopic quantitative picture of the same machine or a random point stereogram of Yan's.

(2) Refractive examination: Atropine paralyzed ciliary muscle optometry, one is to understand whether there is amblyopia, and the other is to understand the relationship between strabismus and refraction.

(3) Determination of eye position and oblique angle: Determine which type of strabismus. The size of the oblique viewing angle must be checked for surgical design.

(4) Eye movement examination: to judge the function of the extraocular muscles.

(5) Is there a compensatory head position: Different head postures can help diagnose which extraocular muscle paralysis.

(6) Determining the examination of the paralysis muscle: the red lens test or the Hes screen method.

(7) Pulling test: 1 Estimate postoperative diplopia and patient tolerance after preoperative traction. 2 is pulled by the test: you can know whether there is mechanical contraction of the extraocular muscles or muscle spasm. 3 active contraction test: understand the function of the muscles.

(8) Inspection of hidden obliqueity: Quantitative measurement is performed by using a hidden inclinometer. Detection of collection points: Helps diagnose muscle fatigue.

(9) AC/A Regulatory Set/Adjustment Ratio: Helps determine the relationship between strabismus and adjustment and set.

Strabismus diagnosis

Diagnostic criteria

1. Ask about your medical history. Ask the patient's age, the exact time of onset, the cause or cause of the disease, the development of strabismus, what kind of treatment, and whether there is a family history.

2. Eye appearance check. Pay attention to the direction and extent of the patient's eye position deflection, whether the cleft is equal, whether the face is symmetrical, and whether there is a compensatory head position.

3. Vision examination and refractive examination. Detailed examination of the patient's far and near vision and corrected vision. For high myopia and astigmatism, as well as adolescent patients, it is necessary to perform a refractive examination after dilatation.

4. Cover test. Do not cover the eye position when the patient is looking at a target 33 cm and 5 meters away.

There are two ways to cover: one is the one-eye covering method in which one eye is covered, which is also called the alternating covering method or the continuous covering method; the other is to cover one eye first and then remove the covering cover. Whether the two eyes can simultaneously look at a target and the eyeball reset speed at the same time, this method can be called masking and non-masking. The occlusion test can be used to characterize strabismus simply and accurately.

5. Check the movement of the eyeball. Six major directions of motion were observed to determine if there was any abnormality in the function of each eye muscle.

6. Oblique viewing angle. The oblique viewing angle is divided into a main oblique angle (first oblique viewing angle) and a secondary oblique angle (second oblique viewing angle). When the eye is fixed, the angle of the oblique eye is called the main oblique angle; when the oblique eye is fixed, the angle of the healthy eye is called the auxiliary oblique angle. Measuring the main and auxiliary oblique angles can assist in the diagnosis of strabismus. The commonly used methods for measuring oblique angles in clinical practice include: corneal reflective spot position measurement, homophone inspection method, and triangular prism matching eye mask method.

7. In addition, there are also squint meters to measure the oblique angle method, the Markov rod plus prism inspection method, the perimeter meter measurement method, and the like.

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