A child’s visual acuity of 4.9 is normal depending on the age and stage of development. 4.9 is considered normal for children before the age of 6 when vision is not fully developed. Children’s eye structure and function are in development from birth to 6 years old. Before eye vision is fully developed, there are different reference values for naked eye vision according to different developmental stages at different ages. Generally speaking, the reference value for naked eye vision at 6 years of age and beyond is 5.0 and above, and it is abnormal if only 4.9 can be achieved. However, for the underdeveloped stage of vision before the age of 6, a visual acuity of 4.9 may be normal. It is recommended that vision screening should be conducted in hospitals at all ages after birth. Attention should be paid to conditions such as insufficient reserve for farsightedness and low visual acuity, and timely measures should be taken to intervene in order to prevent myopia and amblyopia from occurring.