A visual acuity of 5.0 is generally considered normal vision, and most refractive error states are myopic because 4.8 < 5.0 is likely to be myopic if we look at the visual acuity criteria alone. One aspect to note is that the visual acuity standard, in addition to 5.0, is also age-related. Children generally develop their vision to 5.0 or above when they are 8-9 years old, and children under 8-9 years old have a gradual growth and development of vision that does not always reach 5.0 and is not necessarily considered abnormal. Each age group has a lower visual acuity limit, which should not be lower than this lower visual acuity limit, below this lower visual acuity limit is considered to be a delayed development of vision problems. If a three-year-old child's visual acuity is not lower than 4.7, a 4-5-year-old child's visual acuity is not lower than 4.8, and a six-year-old child's visual acuity is not lower than 4.9. If the lower limit of visual acuity for each age group is higher than the lower limit of visual acuity for that age group, it is considered normal, so whether 4.8 is considered myopia or not should be considered in conjunction with age.