When a three-year-old child’s vision or refraction is measured, there are two letters, S or C. Generally, S stands for the spherical lens obtained in the optometry, and C stands for the column lens in the optometry. The spherical lens is the degree of nearsightedness or farsightedness, and the C represents the degree of astigmatism. In general, physiological astigmatism does not exceed 50 degrees, and the degree of spherical lens for children around three years old should be around 150-200 degrees of farsightedness. If it is more than 200 degrees of farsightedness, it does not matter, as long as it does not affect vision, it can be observed. Generally the vision of a child around three years old should be around 0.5-0.6, but if a three-year-old child has myopia after an optometry, it may need to be taken seriously. Because the child has myopia at a relatively young age, as they grow older, the myopia will gradually increase, often forming a relatively high degree of myopia after adulthood. Therefore, you need to take certain ways to prevent and control, you can use a low concentration of atropine to prevent and control the myopia delayed deepening.