If an 8-year-old child has a visual acuity of 4.9, which is lower than the normal visual acuity level, it may be caused by myopia, astigmatism, and so on. Under normal circumstances, the standard visual acuity of 8-year-old children is 5.0. If an 8-year-old child has a visual acuity of 4.9, which is equivalent to a visual acuity of 0.8 on the decimal visual acuity chart, it is slightly lower than the normal standard visual acuity. The child’s vision loss may be caused by myopia, astigmatism and other diseases. It is also possible that the patient’s vision is not fully developed, so the vision is at a lower level. If the examination found that the vision of 8-year-old children 4.9, it is recommended that the children go to the ophthalmology department of regular hospitals, with professional ophthalmologists for refraction and funduscopic examination, to clarify the condition, and comply with the doctor’s instructions for treatment, to improve the vision. Children should also pay attention to eye protection, reasonable eye use, not long time playing electronic products, etc., to avoid excessive use of eyes caused by vision loss.