Hang the ball above the floor about 1 meter. Child lays staight underneath the ball with their head. Let the ball move sideways slowly. The child follows the movement with the eyes while the head lays still. Don’t practice longer then the eyes can handle. This is a good exercice for the eyes wich helps for eye movement needed by reading.
Also a good use of this ball is throw and catch, for eye hand coordination. Because of the cord the ball stays close.