Generally speaking, non-common strabismus can often be examined for a clear cause, while the cause of common strabismus is not yet known. The majority of what we commonly refer to as strabismus is common strabismus. The causes of common strabismus are multifaceted, and even the same patient may have several factors acting together. The most common causes of common strabismus are as follows: 1. Refractive error Patients with hyperopia can suffer from excessive adjustment due to hyperopia and thus convergence. In myopic patients, no or little accommodation is required, resulting in insufficient convergence, which may lead to exotropia. 2, perceptual disorders Due to some congenital and acquired reasons, such as corneal clouding, congenital cataract, vitreous clouding, abnormal macular development, excessive refractive aberration, etc., resulting in retinal imaging, low visual function, bilateral eyes can not establish fusion reflex to maintain eye balance, resulting in strabismus. 3. Genetic factors Since the same family has similar characteristics in eye anatomy and physiology, strabismus caused by anatomical abnormalities may be passed on to the offspring in a multi-gene inheritance.