Whether a visual acuity of 4.9 is myopia is determined by the results of the optometry. If an adult has a visual acuity of 4.9, he or she may be myopic, while a young child before the age of 8 is not considered myopic if his or her visual acuity is 4.9. An adult should have a bare eye vision of 5.0 or higher. If the vision is 4.9, it is lower than normal and is considered mild myopia. Children’s vision is above 4.5 before the age of 8, which is the normal range due to their underdeveloped vision. 4.9 vision is equivalent to what is normally called 0.8 vision, while 5.0 vision is also 1.0 vision, which is standard vision. If an adult has less than standard vision, a refractive eye exam is needed to determine whether the adult has myopia or another condition that is causing the vision loss. In the case of children before the age of 8, if the eyesight is 4.9, do not worry too much and observe. If the eyesight is still 4.9 after the age of 8, it may be myopia, which requires dilated eye examinations and vision correction after a clear diagnosis.