For a child or adult with fully developed vision, a visual acuity of 0.6, whether measured naked or with lenses, is considered abnormal. The criteria for determining whether vision is normal or not vary at different ages and developmental stages. For people with fully developed vision, a naked eye visual acuity of 1.0 and above is considered normal under normal circumstances, and a visual acuity of only 0.6 should be used as a precautionary measure for delayed vision development, amblyopia and refractive errors, etc. However, a visual acuity of 0.6 may be considered normal before the development of full visual acuity. For visual acuity of only 0.6 should be vigilant, especially for children and teenagers should be vigilant about visual developmental delay and amblyopia, etc. It is recommended to consult a doctor in time to improve the dilated pupil optometry and other auxiliary examinations, and under the guidance of the doctor for refractive error correction and amblyopia training in order to restore or improve the visual acuity.