A six-year-old child should have at least 4.9 naked eye vision, which is the normal naked eye vision. Therefore, if the child has a 4.8 visual acuity after the vision test, which is below the normal range, it means that the child may have certain eye diseases, such as refractive error, amblyopia or congenital cataract, or fundus disease. Therefore, further examinations, including optometry, fundus examination and intraocular pressure examination, are needed to understand the specific cause of this condition. If refractive error is the cause of vision loss, early prescription of glasses is needed to improve vision. If amblyopia is present, amblyopia treatment and training will be performed. If there is a congenital cataract or fundus disease, surgery may be required, which will depend on the results of the specific examination.