Hello,
I must admit that I have not used EFT on any infant with lazy eye. However, I would recommend you try the following:
Even though my left/right eye does not want to keep up with my other eye, I am an awesome baby.
Even though my left/right eye is not ready to keep up in this world, I chose to let go of anything that I don't want to see.
Even though my vision is not yet clear, I deeply and completely love and accept myself and am ready for this wonderful life.
Then, as you tap the points either on yourself or on the child, say statements such as... tired eye, not ready, not willing to move forward, not clear, not keeping up, too much to see, not ready, too sleepy, too hard, not strong enough, can't keep up, etc.
I wish you well in helping your grand daughter. Please keep us posted on how this works.