I have managed to create a head and eyes for a character which I smooth bind by selecting both eyes and head and then apply smooth bind.

I have drawn circles to which the eyes are aim constraint with the circle. eyes_aimconstraint

It works great, the eyes follow the circle.

I draw another circle and orient constraint the head so that it can tilt forward and backwards. tilt_head_orientconstraint

Now when I tilt the head, the eyes go out of the socket and does not follow the head.

I decide to draw another 2 circle for the eyes just for positioning and point constraint the circles to the eyes and make it a child of the tilt_head_orientconstraint.

It almost works, but it still goes out of the head.

What is the correct approach to this? I have watched tutorials and all they teach is how to make the eyes follow the circle constraint.