The causes of esotropia, which is also known as esotropia in clinical practice, are categorized into congenital and acquired factors. Congenital factors are mainly genetic factors, but also some growth and developmental defects, and acquired factors include diseases or environmental factors, as follows: 1. Acquired factors: Diseases mainly include refractive errors, such as medium and high hyperopia, hydrocephalus, brain tumors, etc. Environmental factors are mainly caused by long-term use of electronic products, especially the long-term use of mobile phones and other electronic products by myopic patients. Environmental factors are mainly caused by long-term use of electronic products, especially myopic patients who use cell phones and other electronic products for a long time, which may lead to acute common internal strabismus.2. Congenital factors: some small children because of medium and high hyperopia are not corrected, which will lead to internal strabismus, myasthenia gravis, ophthalmic meridian paralysis, oculomotor paralysis, etc., which can also lead to internal strabismus. Some patients have weak eye fusion and incomplete infant development, which leads to inadequate eye fusion and may cause internal strabismus. There are also cases of preterm labor, low birth weight or older gestational age, and mothers who abused drugs and smoked during pregnancy, which may lead to endotropia.