The normal range of vision for a 3 year old is around 0.6. Children can also have their vision checked after school. When the vision is significantly lower than 0.5, or when the difference in vision between the two eyes is more than two lines, it is necessary to have a dilated eye exam, especially a slow dilated eye exam with atropine. The number of days of pupil dilatation is usually 3 days, depending on the combination of high astigmatism or combined internal strabismus. If you have a high degree of hyperopia or astigmatism, you may have a combination of amblyopia, which requires not only glasses but also amblyopia treatment and training. If you are nearsighted after the eye exam, you can correct your vision with nearsighted glasses, and you need to follow up and have another eye exam every six months.