Visual acuity of 5.0 and above is generally considered normal vision, and children aged 8-9 years can usually develop visual acuity up to 5.0 (1.0). However, in addition to visual acuity standards, there are age restrictions. The younger the child, the lower the visual acuity will mostly be, and not necessarily considered abnormal if it does not reach 1.0. A three-year-old child’s visual acuity is generally considered to be at least 0.5, which means that the lower limit of visual acuity is 0.5, and anything below 0.5 is considered abnormal. 4-5 year olds have a lower limit of visual acuity of 0.6, 6 year olds have a lower limit of visual acuity of 0.7, and 7 year olds and above have a lower limit of visual acuity of 0.8. Those who are above the lower limit of visual acuity and have symmetry in both eyes can be observed first and are not considered abnormal. If the visual acuity is below the lower limit of visual acuity and the lower limit of visual acuity for each age group is not reached, further examination at the hospital is needed to clarify whether the cause is refractive error or caused by other eye diseases.