Before strabismus surgery, routine ophthalmic examinations are done, such as checking the cornea, lens, anterior segment of the eye, refractive examination, etc.; special examinations for strabismus are also done, such as eye movement examination, strabismus angle measurement, binocular visual function examination, stereopsis function for seeing far and near, etc. These examinations are all done. In addition, there is a general examination of the whole body for surgery, blood sampling, electrocardiogram and chest X-ray, etc.