Figure 3a: In a healthy person, both eyes will rotate in an opposite to direction to the rotation of the head. The rotational axis of the head and eyes are parallel to one another. The speed of the eye rotation is equivalent to that of the head rotation [after 68].
Figure 3b: In the case of unilateral vestibular failure, the eyes rotate more slowly than the speed which the head moves. The rotation axis of the head and eyes are different. Both result in a diffused and blurred retinal image. [after 68].