1. Imperfect development Children, especially infants, have imperfect development of 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 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, it is said that the period before the age of 5 when the monovision 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 anomalous development of the position of the congenital extraocular muscles, abnormal development of the extraocular muscles themselves, incomplete differentiation of the mesoderm, poor separation of the eye muscles, anatomical defects such as abnormal and fibrotic muscle sheaths or paralysis of the nerves that govern 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. Strabismus generally occurs within 6 months of birth and is called congenital strabismus, which does not have the basic conditions for establishing binocular vision and is most harmful to the development of visual function. 3. The developmental characteristics of the eye make children prone to strabismus. Because children have small eyes and short eye axes, they are mostly farsighted, and because children have large corneal and crystal refractive power and strong ciliary muscle contraction, i.e. strong adjustment power. 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, an internal strabismus is produced; on the contrary, if the abduction is too strong and the collection is not enough or both exist at the same time, an exotropia is produced.