Optometry is the first step in the treatment of strabismus and amblyopia. Whether strabismus or amblyopia, both may be related to refractive error. The first step in the treatment of strabismus and amblyopia is to apply ciliary muscle paralysis for optometry and to wear glasses if there is farsightedness, myopia or astigmatism. Research has found that when the farsighted eye looks at near objects, it needs to use more adjustment than normal people, which will produce more convergence, making the eye appear to be overly inwardly rotated, and it is also easy to develop internal strabismus. When myopic eyes look at near objects, they do not need to adjust like normal people, but both eyes must converge at the same time, which causes eye fatigue because the relationship between adjustment and convergence is not coordinated. In order to avoid visual fatigue, the patient will give up the collection and convergence by himself, and then the exotropia will occur. As long as timely and accurate optometry, the strabismus caused by refractive error can mostly be restored to its proper position.