testing of ocular motility – evaluation of the extraocular muscles

Testing of Ocular Motility – Evaluation of the

Extraocular Muscles Robert P. Rutstein, ODClaudio Busettini, PhD

Review of the EOMs - Anatomy

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)

Actions of EOMs from Primary Position: Horizontal Recti

Actions of EOMs from Primary Position: Vertical Recti

Superior rectus and inferior rectus have adduction as tertiary actions

(View from above of the right eye)

NOSE

not aligned with pivot point

Actions of EOMs from Primary Position: Obliques

Inferior oblique and superior oblique have abduction as tertiary actions

(View from above of the right eye)

NOSE

not aligned with pivot point

Actions of EOMs not from Primary Position

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

Field of Action

Innervation: oculomotor nerve(cranial nerve III)

Somatic motor function: innervation of FOUR of the 6 extra-ocular muscles:- Medial rectus- Superior rectus- Inferior rectus- Inferior obliqueand of the levator palpabrae superioris (upper eyelid)Visceral motor function:-parasympathetic innervation of the constrictor pupillae (pupillary light reflex)- ciliary muscle (accommodation reflex)

accommodation and pupil responses

excycloduction

incycloduction

upper eyelid control

Innervation: trochlear nerve(cranial nerve IV) ONLY FUNCTION: CONTROL OF

THE SUPERIOR OBLIQUE MUSCLE

Innervation: abducens nerve(cranial nerve VI) ONLY FUNCTION: CONTROL OF

THE LATERAL RECTUS MUSCLE

1. Cover test in different positions of gaze

2. Versions and ductions

Clinical Testing

Cover test

Versions/Ductions

Versions/Ductions

Oculomotor (III) nerve palsy

Trochlear (IV) nerve palsy

Abducens (VI) nerve palsy

2 yo with unusual eye movements

Eye movement recordings: - binocular viewing - monocular viewing - version/vergence - testing different types of eye movements

Deficits affecting both eyes (central issues)

MRI and fMRI

Laboratory Testing

Electro-oculography (EOG) Limbus tracking (LEDs and FTRs) Videoculography Search coil

Types of eye movement recordings

Electrooculography (EOG)

Videooculography

Search coil

Example ofoculomotordata

Example of damage to the trochlear nerve in a monkey

MRIDumars 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 arebarely 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 muscleremains 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.