Normal vision develops rapidly during the first 2 years of life and
continues more slowly until about age 9. During that time, a child's eyes and
brain learn how to work together to see. Practice is the most important part of
this learning process. Constant use of both eyes gives a child's eyes and brain
the practice they need to develop normal eyesight.
If there is a problem with vision in one eye, it disrupts this
learning process, and the brain stops developing normal vision for that eye.
This can lead to amblyopia.