Strabismus is commonly known as “squint”, and there are mainly internal and external strabismus. Internal strabismus is commonly known as “crossed eyes” or “opposite eyes”, while external strabismus is commonly known as “oblique white eyes”. The prevalence of strabismus in the population is about 2%, mostly in infants and preschoolers, which can seriously hinder the child’s visual development and produce irreversible damage. The importance of stereopsis The human eye should not only have good vision, but also have accurate binocular vision, i.e. stereopsis, which is the fusion of the visual centers of the cerebral cortex after each eye sees an object at the same time, so that it can accurately determine the object’s “distance, depth, height” of the advanced visual function, which is the biological evolution. This is a perfect result of biological evolution. Except for primates (including humans), most animals do not have stereo vision because their two eyes are on both sides of the head, the field of vision does not overlap, and both eyes cannot see an object at the same time, i.e., they cannot “see with both eyes”, so there is no stereo vision. In humans, the two eyes are located in front of each other, and the visual fields of the two eyes mostly overlap, so they can look at an object at the same time and thus produce stereopsis. Stereopsis is extremely important to perform daily activities. Without stereopsis, one cannot engage in jobs that require fine vision, such as machining, instrumentation, art, construction, etc., nor can one drive a vehicle or skillfully engage in sports activities such as tennis, volleyball, basketball, baseball, golf, etc. As for occupations like aviation, sailing, aerospace, etc., they are even more incompetent. Second, the harmful effects of strabismus 1, strabismus on the eyes. The skewed eye automatically gives up its use, causing the entire visual nerve pathway from the eye to the brain to stay in its original state. When the child has passed the sensitive period of visual development from 3 to 6 years old, the visual nervous system is already “fixed”, and even if the strabismus is cured at that time, it is difficult to improve the visual acuity. Stereopsis requires the simultaneous participation of both eyes. If one eye vision is very poor, it can not be used with the other “good eye”, stereo vision is impossible to establish. 2, strabismus will also affect the child’s physical and mental health. Children with strabismus may suffer greater psychological pressure, low self-esteem, introverted personality, and poor socialization. In the future, they will encounter resistance when choosing employment and spouse. The purpose of strabismus treatment is to establish binocular vision, i.e., stereopsis, in addition to the cosmetic effect. If we wait until the child is older to operate to treat strabismus, not only the visual acuity of the strabismus cannot be improved, but also the stereopsis function cannot be expected. Therefore, as soon as you find out that your child has strabismus, you should take him/her to the hospital for examination and treatment without any delay. For the sake of your child’s eyes and future, parents must remember – strabismus should be treated before it’s too late! May your child be smart and healthy and have bright eyes!