Children with myopia tend to experience a progressive deterioration of their vision until adulthood. The growing process characteristic of childhood affects many bodily organs, including the eyes. As a result, the eyes may change, making myopia worse. Once the eyes stop their growth, which may not happen until early adulthood, the severity of a person's myopia may begin to stabilize.
Myopia is often diagnosed in children between 6 and 12 years of age and may worsen during the teen years. Although little change may occur between ages 20 to 40, myopia may worsen with age, because the children have not developed a good habit of using eyes. Moreover, the children's eyes are under development, if he does not have a good habit of using eyes, the vision will be worsen.
In my opinion, it really depends. children's myopia not always worsen with age, The condition usually starts in childhood and oftentimes becomes worse as children, and their eyes, grow rapidly - especially during the teenage years. It often stabilizes by the time a child is in their twenties, but it is also possible for adults to develop myopia.