A slanted eye is medically called “strabismus”, and a slant to the nose is called “internal strabismus”, while a slant to the ear is called “external strabismus”. Some children are born with good eyes, but when they reach the age of three or four, they suddenly become squinted. Some people say that this is the “strange wind”; some people say that is to see the strong sunlight, and so on, in fact, are not. People’s normal eyes can see both near and far, and can look left and right, up and down movement, and. The two eyes always move together. This is mainly the result of the traction of six muscles around each eye, collaborating with each other and working closely together. If the contraction force of a muscle is too strong or too weak to balance with its counter muscle; or if a muscle is paralyzed and loses its role, the traction force of the eye will also lose its balance, so that the eye will appear to be tilted to one side. The causes of strabismus are as follows (1) Imperfect development: Children, especially infants, have imperfectly developed binocular monocular function and cannot coordinate extraocular muscles well; 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 differentiation of the mesoderm, 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. Strabismus generally occurs within 6 months of birth and is called congenital strabismus. It 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 hyperopic, 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 adjustable 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.