Internuclear ophthalmoplegia (INO)

This patient exhibits a left INO characterized by adduction slowing without ocular limitation. The top picture (A) depicts the patient in a primary gaze position, while the bottom picture (B) depicts the point at which the right eye reaches a 20 degree target while saccading to the right. Note that the right eye reaches the target prior to the left eye, as demonstrated with the midpupillary markers shown. (Note that the left eye has not changed position off of the midpupillary marker.) At saccade end, both eyes achieve target fixation (as shown in the oculogram).