dissociative vertical skew
Introduction
Introduction to Separation Vertical Skew Dissociated vertical deflection (DVD), when the eyes are alternately covered, covers the oblique line of the eye. It is an abnormal vertical movement of the eye that contradicts the general rule of inner strabismus. It often combines occult nystagmus and amblyopia. Can coexist with any other type of strabismus. Separate vertical skew (DVD) is not uncommon in the clinic, usually affected by both eyes, but the degree can be inconsistent. basic knowledge Sickness ratio: 0.05% Susceptible people: no special people Mode of infection: non-infectious Complications: strabismus
Cause
Separation vertical skew cause
Causes:
There are few reports on the pathogenesis of this disease in domestic and foreign literatures. It has not been confirmed by EMG, EOG, ENG and other aspects. Because the oblique viewing angle of DVD is unstable, it often changes, so muscle tissue abnormalities can be ruled out. Because it is contrary to the laws of Sherrington and Hering, it can be negated as the abnormality of innervation, so the real cause of this disease is still unclear.
Pathogenesis:
In 1982, it was suggested that some neuromuscular fluid conduction was caused by the neuromuscular endplate of the superior oblique muscle. Some people thought that the root cause was caused by the separation of the central nervous system. Bielschowsky believed that the vertical deflection was caused by two verticals. Separated by alternating center or intermittent excitement, the gaze is neutralized by the nerve impulses of up and down, so the position is kept unchanged, instead of the upward shift of the eye, but the eye is moved below the midline. Rarely, the so-called vertical separation center in the clinic is largely a hypothesis. There are 4 cases of DVD patients reported in China. It is found that 2 cases of the external rectus muscles are below the starting point, from the back to the top. Traveling, and the attachment point is about 5.5mm from the limbus. Therefore, it is considered that the abnormality of the lateral rectus muscle may be a cause of the DVD. Others think that the upper rectus muscle is stronger or the inferior rectus muscle is weak, and the internal and external rectus muscles are at the same time. There may also be varying degrees of strength and weakness, so in addition to upward deflection, accompanied by internal oblique or exotropia, patients can also be combined with inferior rectus dysplasia and abnormal end position, which can only explain the eyeball Case, turn latent nystagmus and eye movement can not explain tremor-like, in short, the exact pathogenesis remains to be further explored.
Prevention
Separation vertical skew prevention
Reasonable use of the eye, attention to eye health, good eye safety protection, reduce and avoid the irritating and accidental damage to the eyes caused by adverse factors, can play a certain preventive effect. In addition, early detection, early diagnosis and early treatment are also the key to the prevention and treatment of this disease.
Complication
Separate vertical deflection complications Complications
Can be combined with horizontal strabismus, vertical muscle paralysis or excessive, head position abnormalities.
Symptom
Separation of vertical skew symptoms Common symptoms Attention deficits Diffusion Eye fatigue Paralysis Separation status... Separation roaming
1. Symptoms of patients with no obvious symptoms, because of the better vision of both eyes, have a certain binocular vision function, in order to maintain a good binocular single vision, often need to use the convergence to control the upper oblique of the non-dominant eye, thus appearing Can not last, eyelid pain and other symptoms of eye muscle fatigue, when examined with red glass tablets can lead to double vision, no matter what eyes look, the red image seen is always under the white image, such as the use of prisms to measure vertical strabismus degree.
2. Visual acuity is often good, but there are also visual acuity. The cause of vision loss is mostly caused by recessive nystagmus, followed by amblyopia or organic lesions or high refractive error, while DVD and amblyopia are mostly Look at bad or strabismus.
3. Eye position When the eyes are alternately covered, the covering eyes are inclined upwards, and the direction and degree of the upper oblique direction may be inconsistent, sometimes it is outwardly inclined, and sometimes it is inwardly inclined. Due to the difference of fixation eyes, the direction of deflection may also be After the cover is removed, the eye is rapidly down and the inner tremor is turned back to the eye position. The non-gaze is always in a high position. This is a prominent feature of the disease. When fatigue or attention is not concentrated, one eye can Spontaneously inclined, while covering both eyes, there is no upward slanting. Because the degree of separation of the eye points is different during the examination, the degree of the upper slant is often not constant, so when measuring the oblique angle, only a rough figure can be obtained. .
4. binocular visual function patients with this disease can have a certain degree of binocular vision function, some people with 135 cases of DVD combined with horizontal strabismus in the same machine, 64 patients (47.4%) with normal retina, 4 patients with abnormalities (3%) Corresponding to 67 cases (49.6%), but due to the change of the eye position of the DVD, the method of checking the retina corresponds to different methods, and the results are often inconsistent. Cui Guoyi uses the same vision machine, Bagolini linear mirror, Worth four-lamp and rear image 4 A method to check the binocular visual function of the DVD, and comprehensive analysis, that the results obtained close to the actual situation of the patient can be obtained. In the case of a DVD patient without horizontal strabismus, when the positive position is controlled, the normal omentum corresponds, and when the two eyes are merged and destroyed ( If the eye is fatigued, or if it is alternately lit up with the same camera, an upward tilt will appear as a single eye maneuver suppression. At this time, if it is checked by the same machine, it is a vertical anomaly, but with a Bagolini linear mirror or Post-image examination can be a normal correspondence, so it can be considered as a double retina.
5.DVD combined with recessive nystagmus often combined with occult nystagmus, according to the literature reported that about 73.6%, with nystagmus examination, when covering one eye, the occlusion of the occluded eye, the horizontal eyebeat Sexual tremor, fast-phase non-occlusion of the eye side, there are three clinical cases:
(1) Simple horizontal beating nystagmus.
(2) Dominant recessive nystagmus: When there is open gaze in both eyes, there is nystagmus. When one eye is covered, the amplitude of the non-occluded eye becomes larger.
(3) Rotating nystagmus: that is, the occluded eye appears to be fluttering outward and upward, and when the occlusion is removed, the tremor tremor is returned to the original eye position. This kind of rotatory nystagmus is more common in the companion. A DVD patient with exotropia.
6. Eye movement can be expressed in the following three situations:
(1) Eye movement when covering a single eye: When covering one eye, the covered eye slowly rotates outward and rotates upwards. At this time, there is a recessive eye shake. It can be seen that the nystagmus occurs on the fixation side, and the other is hidden. At a glance, the eye that has been turned up slowly rotates inward and turns down to become a fixation eye; when the upper eye starts to become a fixation eye, the other eye begins to move up and observes that the movement can be seen in the same way. The machine alternates the point-of-sight method or the cloud method (using a +20D convex lens).
(2) Bielschowsky phenomenon: a neutral filter with different densities is added in front of the eye to reduce the illumination of the light source. When the density of the filter before the eye is increased, the contralateral eye is lowered from the up position and even becomes a downward slope; If the brightness of the dark lens in the fixation eye is increased, the lower eye will turn up again. This phenomenon is called Bielschowsky phenomenon, and some patients have positive Bielschowsky sign, especially in the dark room.
(3) Abnormal movement when gazing at the side: When gazing at the side, one eye becomes inclined when turning inside, and becomes oblique when turning outward; or when it is turned inside, it becomes inclined, and when it is turned, it becomes oblique. Most of this phenomenon occurs in eyes with poor eyesight.
7. The combined horizontal strabismus DVD can coexist with any type of strabismus. It is clinically possible to combine the following strabismus:
(1) Congenital esotropia is more common. According to foreign literature, 70% to 90% of congenital esotropia is accompanied by DVD.
(2) Alternate exotropia, which is not easily found in the early stage with a DVD, but appears several months after surgery.
(3) Intermittent exotropia combined with accommodative esotropia.
(4) Esotropia coexists with exotropia.
The latter two are collectively referred to as antipodean strabismus, that is, in the same case, the eye position is sometimes oblique, sometimes oblique, or when the right eye is gazing, the left eye is oblique; when the left eye is gazing, the right eye is slanting The specific phenomenon.
(5) Helveston syndrome: a new type of ocular muscle syndrome first described by Helveston, namely the combination of DVD and type A exotropia and hypertonic upper oblique muscles. Two cases of twins were reported in China. Sub-Helveston syndrome may be associated with genetic mutations in identical twins.
The etiology of Helveston syndrome is still unclear. The relationship between exotropia A, DVD, and hyperosseous hyperactivity is also unclear. The enhancement of bilateral superior oblique muscle function may cause exotropia A, but with DVD. There is no clear relationship. Due to the degree of enhancement of the superior oblique muscle function, it is difficult to make a clear judgment when it is mildly enhanced. The DVD is often caused by the degree of symptoms of both eyes, or the potential type of one eye is manifested as monocular strabismus affecting the DVD. Diagnosis, thus preventing a definitive diagnosis of Helvston syndrome.
Helveston divides the superior superior oblique muscle function into 4 levels:
1 : The superior oblique muscle function has just been observed.
2: It can be clearly judged that there is an increase in the function of the superior oblique muscle.
3: The function of the superior oblique muscle is significantly enhanced.
4: In the upper oblique muscle function position, the lower jaw almost completely blocks the cornea.
Most of the intrinsic amblyopia, due to nystagmus, the effect of amblyopia treatment is poor, surgical treatment in the horizontal rectus surgery to correct exotropia, while in the vertical direction to correct the A sign, or the upper oblique muscles, up straight Muscle receding combined surgery.
The incidence of combined horizontal strabismus varies from report to report. The comprehensive domestic and foreign literatures show that there is no significant difference in exotropia.
A typical DVD should have the characteristics that the covered eye is inclined at each diagnostic eye position when it is covered alternately, with recessive or dominant nystagmus, but it is easy to miss the diagnosis under the following conditions.
1. Patients who do not have a simple DVD with horizontal strabismus and those with a small upward tilt have a nervous or over-concentrated gaze during the examination, and the upper oblique is not easily exposed.
2. Combined alternating exotropia or internal oblique often occurs within a few days or months after horizontal strabismus correction.
3. When combined with reverse strabismus, only pay attention to the specific phenomenon of treating reverse strabismus, and ignore the DVD.
4. When the vertical muscle paralysis is combined or too strong, the DVD phenomenon can be masked.
Therefore, in the clinical examination should be done with the same machine, the lights of the left and right eyes alternately extinguished, then the side of the eye on the side of the light-off side can be seen to turn outwards, while the side is turned up, and both eyes are trembled at the same time, and the side of the eye is brightly lit, such as another When the side light is on, the eye rotates inward and downward, and the same machine can be used as a reverse fixation test (RFT) to find a DVD patient that cannot be detected by the filter lens. Check with the objective oblique angle of view, only the eye that is inspected to the side of the light-off side, at this time, the eye on the side of the light-up side can appear up-slope, adjust the height of the picture on the side of the light-emitting side, and then let the side of the light look at the picture until the picture is turned on. Light up the side of the eye does not move, the same method to check another eye, in addition to the same machine inspection, there is Bielschowsky test, cloud test, bottom-down prism placed in front of the squinting and alternate cover method can be found to varying degrees DVD.
Examine
Separate vertical deflection check
No special laboratory tests are required.
1. Vision examination For the visual acuity examination of DVD, due to its combined occult nystagmus, another nystagmus occurs when the eye is covered. The gaze can not be fixed, which will affect the visual acuity test results. Therefore, the following methods should be taken when examining the visual acuity of the disease. :
(1) Cloud method: that is, the 4D ~ 8D lens is placed in front of the non-gaze eye so that its visual acuity is lower than that of the examination eye, so as to avoid inducing hidden nystagmus.
(2) Indirect occlusion method: that is, the "L" type board is inspected before the non-inspection eye.
Through the above method, it can be identified that the loss of vision is caused by recessive nystagmus or original amblyopia.
2. Eye position examination The common methods for clinical examination of DVD eye position are as follows:
(1) Richard method: the bottom-down triangular prism is placed in front of the squint, and then alternately covered, and the degree of the upward inclination is measured.
(2) Krimsky method: that is, looking at the triangular prism in front of the eye, gradually increasing the degree until the oblique point of the squinting cornea is located at the center of the pupil. This prismatic degree is the degree of deviation of the eye position. This method is only applicable to those with poor fixation of the oblique eye. .
(3) Same-view machine inspection method: the picture is merged with a small degree, and the test is performed by alternating the light-off method. The extinguishing time is relatively long, and it is easy to observe the up-and-out rotation of the side eye.
(4) Convex lens method: a 10D ~ 20D convex lens is placed in front of the eye to be separated, so that the eye position can be separated, and the up and outside rotation of the eye can be observed. This method can be used as a method for discriminating between DVD and upper oblique. One (Figure 1).
Diagnosis
Diagnostic differentiation of separation vertical deviation
The DVD should be differentiated from the following extraocular muscle abnormalities:
1. The upper oblique tilt is generally a single eye. When the line is alternately covered, the eye position is inclined when the upper oblique eye is covered; when the upper oblique eye is used as the eye, when the other eye is covered, the lower eye is inclined, for example, the right eye is hidden. Oblique, when the right eye is covered, the eye turns up, such as the right eye fixation, the left eye when the left eye is covered, and the concealed nystagmus is not accompanied, and the eyes are upturned when the DVD is alternately covered, and often accompanied by hidden Erotic nystagmus,
2. When the inferior oblique muscle function is too strong, when the eye is gazing to the side, when the external eye is used as the gaze eye, the inner turning eye is inclined upward due to the excessive oblique muscle, and when the eye is turned into the eye, the outer eye is inclined downward. While the DVD patient is looking straight ahead or sideways, the inner turning eye always appears as an upslope.
3. The superior oblique muscle function is more than secondary to direct antagonism of the inferior oblique muscle paralysis and contralateral lower rectus paralysis. It can be combined with internal oblique or external oblique, and the external oblique is more, showing the vertical deviation of the first eye position. Small, the eye is slightly inclined when the eye is fixed, and the eye is slightly inclined when the eye is fixed, and the DVD is always tilted regardless of any eye fixation (Table 1).
