An eye axis length of 25 millimeters in a 12-year-old patient is a more serious condition and usually indicates that the child has developed myopia. The length of the eye axis in children and adolescents gradually lengthens with age, usually from about 16 millimeters at birth to about 24 millimeters in adulthood. Under normal circumstances, the length of the eye axis of a 12-year-old child is usually around 20 millimeters, and if a 12-year-old child’s eye axis reaches 25 millimeters, it is an abnormal condition. The length of the axial length of the eye is closely related to myopia, and an increase of about 1 millimeter in axial length leads to an increase in myopia of about 300 diopters. Therefore, if a 12-year-old child reaches 25 millimeters, it means that the child is currently myopic, and the child should undergo further optometry to see if high myopia has developed. It is recommended that children with myopia be seen promptly for evaluation of their condition and treatment as prescribed by their physician.