intermittent exotropia
Introduction
Introduction to intermittent exotropia Intermittent exotropia (intermitentexotropia) is a kind of strabismus between the oblique slant and the common exotropia. It means that the visual axis is often separated, which occurs at the beginning of the distance. When looking far, the fusion spreads. Exceeding the convergence range of the fullness, that is, the external oblique is generated, and before the occurrence of the intermittent external squint, there is an external oblique. Common symptoms are photophobia. In outdoor sunlight, the eye is often closed. The reason is unknown. It is estimated that the patient looks at a distant target outdoors, no near-object stimulation, so that the two eyes gather, and the bright sunlight flashes the retina, which interferes with the fusion. Intermittent exotropia often occurs in children's early stage. It occurs only when it is far away. As the disease progresses, the number and time of intermittent exotropia increase. In the end, it can also occur exotropia, intermittent. The slanting period of exotropia often occurs when fatigue, illness, drowsiness or lack of concentration. Intermittent exotropia may have temporary diplopia in visually immature children, which is soon suppressed and has abnormal retinal correspondence. basic knowledge The proportion of illness: 0.003% Susceptible population: occurs in early childhood Mode of infection: non-infectious Complications: strabismus
Cause
Causes of intermittent exotropia
Incomplete development (45%):
Children, especially infants, have imperfect monocular function and cannot coordinate the extraocular muscles well. Any unstable factors can cause strabismus. The single vision function of human beings is gradually developed. The function is established like the visual function, which is repeatedly stimulated by the clear image of the outside world, gradually developing and maturing. Only 2 months after the birth of the baby, there is only a general fusion. The establishment of the precise fusion function will last until the age of 5, and the stereoscopic vision will be established at the latest, and it will be close to the adult when 6 to 7 years old. Therefore, it is the high incidence period of children's strabismus during the period when the single-eye function of the eyes is not perfect before the age of five.
Congenital anomalies (15%):
This strabismus is mostly caused by abnormal development of the position of the extraocular muscles, abnormal development of the extraocular muscles, incomplete differentiation of the mesoderm, poor separation of the eye muscles, abnormal musculoskeletal and fibrotic anatomical defects or nerve paralysis that innervates the muscles. To. There are also some cases of cerebral hemorrhage caused by the use of forceps in the production of the baby's head and face damage or excessive force in the mother's production to produce fetal punctiform hemorrhage, and the bleeding just causes extraocular muscle paralysis at the nucleus that dominates the eye movement. In addition, there are also genetic factors. The strabismus is not a member of the family, and this defect is often indirectly transmitted to the next generation of children. Generally, strabismus is called congenital strabismus within 6 months of birth. It does not have the basic conditions for establishing binocular vision, and it is the most harmful to the development of visual function.
Abnormal eyeball development (10%):
Because the child's eyeball is small, the eye axis is short, mostly for hyperopia, and because of the large refractive power of the cornea and crystal of the child, the contraction of the ciliary muscle is strong, that is, the adjustment force is strong. Such children need more adjustment force when they want to see the object, and the eyes also force to turn inward to produce excessive convergence, which is easy to cause esotropia. This type of oblique vision is called an adjustment internal oblique.
Insufficient eye movement control (10%):
If the set is too strong or the abduction is insufficient or both exist, the internal oblique is generated; on the contrary, if the abduction is too strong, the set is insufficient, or both exist at the same time, the external oblique is generated.
Prevention
Intermittent exotropia prevention
Although exotropia is intermittent, in order to treat and prevent the development of strabismus, it should be treated as soon as possible. In order to prevent the constant exotropia caused by monocular inhibition, surgical correction should be performed in time. In addition, pay attention to eye hygiene, prevent infection or improper use of the eye to cause oculomotor dysplasia.
Complication
Intermittent exotropia complications Complications
Intermittent exotropia can be combined with AV signs, and can also be accompanied by other vertical strabismus, such as discrete upper strabismus.
Symptom
Intermittent exotropia symptoms Common symptoms Rhomboid - Phenomenon inattention strabismus Double vision Photophobia eyelid drooping
Intermittent exotropia often occurs in children's early stage. It occurs only when it is far away. As the disease progresses, the number and time of intermittent exotropia increase. In the end, it can also occur exotropia, intermittent. The slanting period of exotropia often occurs when fatigue, illness, drowsiness or lack of concentration. Intermittent exotropia may have temporary diplopia in visually immature children, which is soon suppressed and has abnormal retinal correspondence.
Common symptoms are photophobia. In outdoor sunlight, the eye is often closed. The reason is unknown. It is estimated that the patient looks at a distant target outdoors, no near-object stimulation, so that the two eyes gather, and the bright sunlight flashes the retina, which interferes with the fusion. The patient changes from the oblique to the obvious, but it is not necessarily certain that the patient closes one eye to avoid double vision. It is possible that the bright light affects the fusion set amplitude of the intermittent exotropia patient and closes the eye.
Intermittent exotropia can be combined with AV signs, and can also be accompanied by other vertical strabismus, such as discrete upper strabismus.
Examine
Intermittent exotropia
All strabismus items should be inspected. The characteristics should be measured for the angle of diagnosis. For example, if you look at the far angle, it is best to let the patient gaze at a target of >6m away to fully check the number of external slopes and determine the type of exotropia. The timing and treatment of treatment are different. Correction of refractive error should be corrected during measurement to control its regulation. If intermittent exotropia occurs only when looking far, and the far angle is greater than the near oblique angle of at least 15, it should be done. Cover test, cover for 30 to 45 minutes at a glance, when removing the cover, the two eyes must remain separated, that is, when the cover is removed at one glance, the other eye must be blocked by the universal eye shield. When the cover is opened, the prism is used to replace the cover test and the measurement is quickly measured. Degree, and then look at the far slope, so that patients do not have the opportunity to fuse, compare the results with the slope before covering, Burian and Franceschetti observed a group of 237 surgical patients, only 10 were separate process type, thus It seems that most patients with exotropia look at a far angle larger than the near angle, which should be attributed to a similarly too strong type.
Measure the skewness of the up and down rotations to determine the presence or absence of the AV sign.
To measure the oblique angle when looking to the left and to the right side, is there any lateral incomitance problem? By definition, the lateral non-commonity refers to the patient with external obliqueness. The slope is 20% less than the first eye position deviation. Clinical practice has shown that patients with lateral non-commonity are prone to overcorrection and cause V.
Check the stereoscopic sharpness: the patient must measure the stereoscopic vision during the slanting period. If the stereoscopic vision is not normal, it indicates that the stereoscopic vision is caused by the intermittent oblique slanting. The stereoscopic vision continues to decrease within a few months, which is a powerful explanation for the surgical correction interval. Surgical indications for sexual exotropia.
Diagnosis
Intermittent exotropia diagnosis and differentiation
Differential diagnosis
Both external oblique and intermittent exotropia are strabismus caused by low internal fusion function, and their identification is difficult.
External shadow: Short-term pain, eye pain, unsustainable reading, unclear vision, diplopia, etc., must be closed for a while before continuing to read, but the symptoms appear soon. Clinically, a series of examinations are sometimes performed according to refractive error, glaucoma or neurasthenia, and corrective glasses are worn, but the symptoms have not been relieved.
