The normal value of the eye axis in a 3-year-old child is about 23 millimeters, with a growth rate of about 0.1 to 0.2 millimeters per year and a reserve of about 200 to 250 degrees of hyperopia. The growth rate of the eye axis and the length of the existing eye axis are important for the prediction of the degree of myopia progression in the future, and for the calculation of the number of existing refractive errors. the normal value of the eye axis of a 3-year-old child is about 23 millimeters, and the growth rate of the eye axis is about 0.1-0.2 millimeters per year, so that the length of the eye axis can reach 24 millimeters in adulthood. If the length and growth rate of the axial length of the eye is abnormal around the age of 3, parents need to be alerted. If the length of the axial length of the eye exceeds the normal range, the child may develop myopia. It is recommended that children with abnormal axial lengths should be seen promptly for evaluation and treatment as prescribed by the doctor.