Congenital esotropia, also known as infantile esotropia (IE), is a condition in which the eyes deviate inward at birth or within the first six months of life, with an incidence of 0.25%-0.50%. Its clinical features include a large angle of deviation with alternating gaze, the absence of binocular vision, and often accompanied by latent nystagmus, vertical disparity deviation, etc. Due to its early onset and constant nature, the damage to binocular vision function is more severe than that of other types of strabismus, and usually requires surgical correction of the eye position to improve the child\'s binocular vision function. However, the timing of IE surgical intervention has always been a topic of concern and controversy among doctors: some scholars believe that surgery should be performed in the early stage (within 4-6 months after birth) or the early stage (2 years before), as early surgery is beneficial to the recovery and establishment of binocular vision function in children; others argue that surgery should be performed in the late stage (2 years after birth), as if the child is too young, the preoperative examination results may not be accurate, the amount of surgery is difficult to determine, and the incidence of overcorrection and undercorrection is higher, and the improvement in visual function after surgery is not significant. Therefore, it can be seen that the earlier the surgery is performed, the higher the risk of secondary surgery; if it is too late, there is a risk of missing the opportunity to establish good stereoscopic vision. Therefore, finding the optimal surgical timing between 3 and 24 months after birth, based on the surgical alignment rate and the success rate of stereoscopic vision establishment, is an important clinical issue.

In recent years, Professor Ing M R has reported 16 cases of patients who underwent correction surgery within 6 months of birth, finding that visual quality of patients who underwent eye position correction surgery between 4-5 months after birth was not better than that of patients who underwent surgery at 6 months or older, suggesting that not all patients have the potential to establish normal binocular vision. The study reported that the occurrence of exaggerated inferior oblique muscle activity and separation of vertical deviation (DVD) after surgery can affect the recovery and establishment of binocular vision, suggesting that dysfunction of visual cortex motor processing can also affect binocular vision. Furthermore, some children with congenital esotropia were found to have hidden white matter softening lesions, suggesting that IE patients have hidden damage to brain structure. Therefore, various causes of brain structure abnormalities are important factors affecting the establishment of stereoscopic vision, and it is very necessary to use safe non-invasive imaging technology and genetic testing technology to further understand the characteristics of brain structure and function before and after surgery in IE patients, the timing of surgery, and the relationship with the establishment of binocular vision.

In recent years, increasing evidence has shown that the onset of congenital esotropia (etiology) is related to primary disorders of the visual cortex and motor processing centers in the brain of the patient: Some children with congenital esotropia were found to have hidden white matter softening lesions, cerebellar hypoplasia, or obvious decoupling trends in functional connectivity networks in brain regions, suggesting that abnormalities in brain structure and function (etiology) are closely related to eye position. More importantly, the preliminary functional MRI analysis conducted by the research team found that the longer the duration of congenital esotropia, the greater the negative impact on the child\'s brain structure and function network connection. After the strabismus in congenital esotropia patients was corrected by surgery, there was a widespread improvement in the functional network connection of the brain, suggesting that changes in visual experience can cause changes in human brain function and structure. Therefore, by analyzing the characteristics of brain structure and function before and after surgery in patients, it is possible to provide imaging evidence for the choice.