Visual acuity is the ability of the retina to distinguish images. Fetal vision is formed as early as the mother’s fourth week of pregnancy. At this time, the fetal eye is small and is covered by a layer of cortex. In the next four to five months, the eye meridians, blood vessels, crystalloids and retina begin to develop, and by the end of the sixth month, the fetal eye has developed considerably. After birth, the baby’s vision is gradually developed and perfected, gradually reaching the state of adult vision at the age of 6-7 years, and after the age of 8 years, the eye reflex is already solid and the development of vision is basically over. Newborns within 28 days of birth, eye development is not complete, the visual structure, optic nerve is not yet mature, vision is only 1/30 of the adult. 1 to 3 years old children’s vision development standards can reach about 0.1 to 0.6 between. During this period, the establishment of the baby’s stereo vision is nearly complete. 4 to 6 years old children’s vision has gradually matured, the clarity of vision increased, 6 years old basically reached the level of adults. Various eye physiological reflexes have been formed and tend to stabilize, at this time is not easy to lose vision. 6 to 7 years old into the adult visual state. At the age of 8 years old, the baby’s eye reflexes have been very solid, the basic end of vision development. It is not until about 12 years of age that the child’s vision development becomes completely stable and reaches its optimal state.