Visual acuity is the most important criterion for reflecting good or bad visual function, and when a child has an eye problem, it is easier to draw parents’ attention if there is a change in appearance. Some eye diseases are not abnormal in appearance, painless, children do not understand, parents do not pay attention, and therefore often miss the best time for treatment, as parents need to often care about their children’s vision, in the absence of a vision chart, the following performance can help find the child’s vision: ① compared with children of the same age, the degree of distance and clarity of vision. ②For children who go to school, let them sit in the back row of the classroom and observe whether they can read the words on the blackboard. ③Whether you need to lean closer to read or watch TV to see clearly. ④Whether there is any change in eye position, whether the position of both eyes is symmetrical, whether there is strabismus, etc. Generally speaking, children should learn to use the vision chart to check their vision as early as possible. Infancy is an important stage of eye development, but infants cannot actively reflect their vision, and it is difficult for others to check vision for infants, so infant vision is often neglected. However, you can carefully observe whether the infant’s vision is normal from some eye-related actions. When an infant is born with only a sense of light, the pupil can be seen to narrow immediately when a flashlight is shone on the black eye, which is called the “response to light. The presence of the “light response” means that the infant has a sense of light. At full term, infants can see hands, bottles, toys, and other objects moving in front of them, but their eyes do not turn with the movement of their hands, and they can only blink when they see something, i.e., the “transient reflex”. At 3 months of age, the eyes can follow a slow-moving object and turn, i.e., the “follow movement”, when vision reaches about 0.02. The eyes can then gaze at the object for a short time, called the “fixation reflex”. At 6 months of age, visual acuity can reach more than 0.5, and from 3 to 6 years old, it can reach normal visual acuity of 1.0. Infancy is a critical period for visual development, so if you find that your infant or toddler has poor vision, you should go to the relevant hospital as soon as possible for examination and early treatment to prevent the formation of amblyopia.