An eye axis of around 24 millimeters is considered normal for adults, but for developing children and adolescents it may indicate true myopia. At birth, the length of the eye axis is about 16 millimeters, and the length of the eye axis will gradually increase during the developmental stage of children and adolescents. An eye axis of 24 millimeters or more during the developmental stage or earlier is abnormal, and it has a certain significance in the estimation of true myopia and myopia, and in this case, measures should be taken to prevent and control the occurrence and development of myopia. However, if the eye axis of an adult is around 24 millimeters, it belongs to the normal range. Since this data is based on statistics, it is also possible that individual differences may manifest themselves as abnormalities, such as myopia. Whether the eye axis length is normal or not and whether there is refractive error or not, it is recommended to go to a professional organization to improve the optometry and other auxiliary examinations to clarify, and to correct myopia or other conditions in a timely manner.