Robert P. Rutstein, OD Claudio Busettini, PhD Directions of eye movements Adduction: movement towards the nose Abduction: movement away from the nose (think abduction of a person: taken away) Elevation: movement upward Depression: movement downward Intorsion or incycloduction: torsional rotation towards the nose Extorsion or excycloduction : torsional rotation away from nose (think extorsion of money: taken away) not aligned with pivot point NOSE Superior rectus and inferior rectus have adduction as tertiary actions (View from above of the right eye) NOSE not aligned with pivot point Inferior oblique and superior oblique have abduction as tertiary actions (View from above of the right eye) THE DIRECTION OF ACTION DEPENDS ON WHERE WE ARE WITH RESPECT TO THE MUSCLE PLANE: KEY FACTOR TO CONSIDER WHEN WE TEST OUR PATIENTS LOOKING AWAY FROM PRIMARY POSITION Somatic motor function: innervation of FOUR of the 6 extra-ocular muscles: - Medial rectus - Superior rectus - Inferior rectus - Inferior oblique and of the levator palpabrae superioris (upper eyelid) Visceral motor function: -parasympathetic innervation of the constrictor pupillae (pupillary light reflex) - ciliary muscle (accommodation reflex) upper eyelid control incycloduction accommodation and pupil responses excycloduction ONLY FUNCTION: CONTROL OF THE SUPERIOR OBLIQUE MUSCLE ONLY FUNCTION: CONTROL OF THE LATERAL RECTUS MUSCLE 1. Cover test in different positions of gaze 2. Versions and ductions Eye movement recordings: - binocular viewing monocular viewing version/vergence testing different types of eye movements Deficits affecting both eyes (central issues) MRI and fMRI Electro-oculography (EOG) Limbus tracking (LEDs and FTRs) Videoculography Search coil Dumars et al. (2008) Magnetic resonance imaging of the endophenotype of a novel familial Möbius-like syndrome Quasi-coronal MRI of posterior right orbit (left column), mid-orbit (middle column), and anterior orbit (right column) for Case1 (top row), Case 2 (middle row), and Case 3 ( bottom row). As seen in the left column, the extraocular muscles are hypoplastic in the posterior orbit and motor nerves are barely detectable. There is relative sparing of the medial rectus (MR) muscles, which appear larger than the inferior (IR), lateral (LR), and SR muscles in the posterior orbit. Note larger rectus muscle cross sections in the mid-orbit (middle column) and anterior orbit (right column), although the levator muscle remains attenuated in the anterior orbit (right column). Note infraplacement of the lateral rectus (LR) relative to the medial rectus (MR) in Cases 1 and 2.