Final answer:
In RIGHT internuclear ophthalmoplegia, when a patient attempts to look left, the left eye will move normally, but the right eye will not move medially or will do so weakly, resulting in asymmetrical eye positioning and possibly diplopia.
Step-by-step explanation:
When you ask a patient with RIGHT internuclear ophthalmoplegia to 'look to the left,' their eyes will exhibit abnormal movement. The left eye will move normally and turn to the left, due to normal function of its lateral rectus muscle. However, the right eye will not move medially, or will do so very weakly, because the medial rectus muscle, which is responsible for adduction (movement towards the midline), is not receiving the proper innervation due to the lesion in the medial longitudinal fasciculus (MLF).
This results in a deficiency of conjugate horizontal gaze. The patient may experience diplopia, or double vision, because their eyes are not aligned on the same visual target. This condition affects horizontal eye movement control, and specifically, it involves the connection between the abducens nucleus on one side and the oculomotor nucleus on the opposite side that innervates the medial rectus muscle. Therefore, when the affected individual attempts to look to the left, the lack of coordination between these muscles leads to one eye turning leftward while the other fails to move in conjunction, creating asymmetrical eye positioning.