Occasionally, internal obliquity can occur secondary to external oblique surgery. For example, in the case below, one year after external exotropia correction, there was a secondary internal obliquity, diplopia, and a compensated head position with mandibular inversion. The child expressed that he could only see as one when his jaw was inwardly retracted and was double-visioned in all other positions. Because diplopia had been affecting the child’s school life for a long time, the parents wanted to have it corrected, so we operated on this patient. We used supervised anesthesia combined with our own modified subfascial anesthesia. Although the patient was only 12 years old, he cooperated well with the surgery and did not experience any significant pain or discomfort during the operation. After surgery, the eye position was orthotropic in all directions, and the compensated head position disappeared completely. If there is no change in the secondary internal obliquity for 6 months after surgery, it can be corrected by reoperation. In addition, slightly older children can tolerate local joint supervised anesthesia, avoiding the risk of general anesthesia. Pre-operative eye position photo of the patient: Note: when looking down, the internal obliquity is aggravated, and when looking up the eye position is good, so the child’s lower jaw is tucked in and he sees with the upper field of vision. On the postoperative day, diplopia completely disappeared, all directions were orthotropic, and when looking downward, there was no more internal obliquity. In comparison with the preoperative and postoperative compensated head position, the preoperative jaw had to be inwardly retracted and both eyes were upturned to overcome double vision; on the postoperative day, the head position disappeared, and the child could see in all directions, such as directly in front, below, and as one. As we can see from this case, modern strabismus correction surgery is already in line with international standards, and does not require complicated preparation before surgery. There is also no need to cover the eye and other operations after surgery, and the eye can be opened freely and can leave the hospital the next day. There is no need to rest for a long time after the operation, usually patients only need to rest for one or two days, and some patients go to work or school the next day without any major hindrance. The postoperative medication only needs to be maintained for a week or so.