A child’s visual acuity of 4.9 is not necessarily myopia, but may also be due to other refractive errors such as hyperopia or astigmatism. 1. Myopia: normal human vision can generally reach 5.0 and above (China’s visual acuity table standards), if the child’s visual acuity of 4.9, suggesting that lower vision, may be caused by myopia, myopia refers to the light through the eye refractive system (lens, cornea, etc.) focal point falls in front of the retina. Nearsightedness is characterized by the inability to see far objects and the ability to see near objects. 2. Hyperopia: Generally speaking, preschool children are in the period of growth and development, there can be physiological hyperopia, if there is no pathological reasons, vision can gradually develop to normal vision with the growth of age. 3. Astigmatism: Children with visual acuity of 4.9 may also be caused by astigmatism or other refractive errors. Children with visual acuity of 4.9 should go to the ophthalmology department of the local hospital, complete the relevant examinations, make a clear diagnosis, and treat the symptoms as soon as possible.