Most children with strabismus have vision problems and may have amblyopia and refractive errors (myopia, hyperopia, astigmatism). Strabismus and amblyopia can be causative of each other, and it may be that strabismus causes amblyopia or that amblyopia develops first and then strabismus; however, strabismus does not cause myopia, hyperopia, or astigmatism in children; these refractive problems just easily coexist with strabismus and make it worse. When strabismus is combined with amblyopia, in principle, we should try to cure the amblyopia first, or at least make the vision in both eyes more balanced, and then have strabismus surgery. If strabismus surgery is performed in the case of monocular amblyopia or binocular amblyopia, post-operative amblyopia treatment will also be performed, which may affect the post-operative eye position of the strabismus. If poorer results are found during amblyopia treatment, surgery may be done to correct the strabismus before treating the amblyopia, depending on the individual. Children with strabismus with amblyopia will be treated by masking the amblyopia first. The amblyopic eye is forced to see by covering the eye with better vision, so that the amblyopic eye is fully exercised. The method of masking is determined by the age and condition of the child, and is reviewed periodically to check whether the vision of both eyes has gradually recovered, and the doctor adjusts the duration of the masking according to the change in vision to avoid a loss of vision in the masked eye. For children with strabismus accompanied by refractive error, surgery can be considered after glasses are worn to correct the vision so that the child can see clearly; or the vision of both eyes is relatively balanced to exclude strabismus caused by refractive problems. In addition, since refractive adjustment problems may affect the degree of strabismus, it is necessary to re-measure the degree of strabismus after wearing nearsighted or farsighted glasses to provide a basis for surgery. Strabismus surgery does not solve the refractive problem, so the child will continue to wear glasses to correct the refractive problem after surgery.