Intermittent exotropia is the most common type of strabismus in clinical practice. Many parents do not know when to observe and follow up and when to operate. Let me briefly say a few words about this issue. Simply put, our two eyes can judge the stereopsis of an object when we look at it at the same time. If one eye is skewed, stereopsis will disappear over time and our visual function will be impaired. Once stereopsis is compromised, surgery is needed to correct the eye position to the right position and then a series of functional training to bring back the lost binocular vision. The results of binocular vision are obtained through a simultaneous vision machine examination, but only children 4 years of age and older can understand and cooperate with this examination. For children under the age of 4, we can estimate whether their binocular vision is impaired by observing how long their eyes are in a skewed position throughout the day, and if they are in a skewed position for most of the day, it is estimated that their binocular vision is impaired and surgery can be considered at that time.