Amblyopia. Treatment for amblyopia is mainly giving that eye its full correction for glasses and/or patching the better eye to stimulate the amblyopic eye. Surgery may also help to align the eyes and possibly allow for stereovision to better develop. There is no clear evidence that "vision therapy" helps in any way except to make the parents hopeful and poorer.
Unlikely. If amblyopia is not addressed by age 7-8 or so it is permanent and vision therapy is usually unsuccessful at restoring good vision.