If the cornea and lens don’t change, but the eye becomes longer, a patient will become nearsighted since the image that previously focused on the retina will now come to focus in the same place, but now in front of the retina.
This is the most common cause of nearsightedness in younger patients. During periods of long bone growth, the eye will grow longer also. As with the cornea, a very small change in the length of the eye will result in a noticeable shift into nearsightedness. This is quite common in boys and girls, starting around age 10 and ending around age 16 for girls and 20 for boys (like we’ve been told, we males mature later than the ladies do and your eyes are no exception).
Until the patient is done growing, it is normal for the amount of nearsightedness to increase every six to twelve months. There have been several studies showing that Vision Shaping Treatment may slow down the development of nearsightedness, but the jury is still out to some degree on this cause and effect relationship.