The normal visual acuity of a 4-year-old is usually around 0.7-0.8. In general, a 4-year-old child needs to be taken seriously if his or her vision is significantly below 0.5, or if the difference in vision between the two eyes is more than two lines. A hospital visit is usually required for an optometric examination, a slow dilated pupil examination with atropine if necessary, and a manual check-optometric examination. This will determine whether the child’s refraction is due to myopia, high hyperopia or astigmatism, and will allow for the fitting of glasses based on the prescription. If there is also amblyopia, not only glasses but also amblyopia treatment and training will be required to improve the vision.