Final answer:
Internuclear ophthalmoplegia (INO) is an ocular motility disorder often seen in patients with damage to the abducens nerve or the medial longitudinal fasciculus (MLF). It causes a deficit in conjugate lateral gaze and can result in double vision or diplopia. Testing involves tracking the movement of a stimulus without moving the eyes.
Step-by-step explanation:
Internuclear ophthalmoplegia (INO) is an ocular motility disorder often seen in patients with damage to the abducens nerve or the medial longitudinal fasciculus (MLF), which affects the movement of the eyes. INO is characterized by a deficit in conjugate lateral gaze, where the lateral rectus muscle of one eye does not contract while the other eye adducts, resulting in double vision or diplopia. This condition can be tested by having the patient track the movement of a stimulus without moving their eyes.