Strabismus is a phenomenon in which the visual axis of both eyes cannot look at the same target at the same time, and only one eye looks at the target while the other eye’s visual axis deviates to the side of the target. There are many kinds of strabismus, the most common one is the inward strabismus, which is medically called internal strabismus, commonly known as “opposite eye” and “crossed eyes”. The most common type of strabismus is inward strabismus, which is known as “crossed eyes” and “crossed eyes”, and outward strabismus, which is known as exotropia. Of course, strabismus does not only refer to cases where the relative position of the two eyes is obviously deformed, but also includes cases where the obliquity is so small that it is not easily detectable on the surface, but the visual function of both eyes is not normal, and also includes those cases where there is no oblique position at all but both eyes are not normal. Therefore, the concept of strabismus should be understood as an abnormality in both the relative position of the two eyes and the visual function of both eyes. Why is strabismus likely to occur in childhood? The main reasons are as follows: 1. Imperfect development: Children, especially infants and young children, have imperfectly developed binocular monocular function and cannot coordinate extraocular muscles well, so any unstable factors can contribute to the occurrence of strabismus. The monocular function of human is gradually developed later in life, and the establishment of this function is gradually developed and matured by repeatedly receiving the stimulation of external clear images, just like the visual function. The establishment of precise fusion function lasts until after 5 years of age, and the establishment of stereopsis is the latest, and can approach that of adults only at 6-7 years of age. Therefore, the period before the age of 5 when the monocular function of both eyes is not perfect is the high incidence of strabismus in children. 2. Congenital anomalies: This kind of strabismus is mostly caused by anatomical defects such as abnormal development of the position of the congenital extraocular muscles, abnormal development of the extraocular muscles themselves, incomplete mesodermal differentiation, poor separation of the ocular muscles, abnormal and fibrotic muscle sheaths, or paralysis of the nerves innervating the muscles. In some cases, the head and face of the baby are damaged by the use of forceps during delivery, or the mother exerts excessive force during delivery, resulting in punctate hemorrhage in the brain, and the hemorrhage happens to be in the nucleus of the nerve that governs eye movements, causing extraocular muscle paralysis. In addition, there is also a genetic component. Strabismus is not inherited in all members of the family, and the defect is often inherited indirectly to the next generation of children. Generally, strabismus occurs within 6 months of birth and is called congenital strabismus, which does not have the basic conditions for establishing binocular vision and is the most harmful to the development of visual function. 3, eye development characteristics make children susceptible to strabismus: because children’s eyes are small, the eye axis is short, and they are mostly hyperopic, and because children have a large corneal and crystal refractive force, the ciliary muscle contraction force is strong, that is, the adjustment force is strong. Such children need more adjustment force to see objects clearly, and at the same time, both eyes also turn inward with force to produce excessive convergence, which easily causes internal strabismus, and this kind of internal strabismus is called regulatory internal strabismus. 4. Insufficient control of the eye movement center: if the collection is too strong or the abduction is not enough or both exist at the same time, it produces an internal strabismus; on the contrary, if the abduction is too strong and the collection is not enough or both exist at the same time, it produces an exotropia.