Lecture 16- Clinical examination of eye movement Flashcards
aim of eye exam
Need to isolate an action of each muscle to test them
basics of eye exam
- Ask pt to keep head still and follow finger
- In H shape
- Some muscles share
movements of eye (when in resting position)
action of lateral rectus
- Straight forward as performs one action on the eye
- Abduction- lateral
action of medius rectus
Straight forward as performs one action on the eye
- adduction (medial)
Elevation and depression (in midline) involves
two muscles
e.g. elevation (SR/ IO)
e.g. depress (SO/IR)
outline action of superior rectus
elevate
adduct
intort
outline action of inferior oblique
elevate
abduct
extort
outline action of inferior rectus
depress
adduct
extort
outline action of superior oblique
depress
abduct
intort
- Muscles responsible for elevation and depression differ depending on
starting position of eye
- Isolating elevation and depression action of SR/IO and IR/SO
*
Cannot be isolated when testing from midline starting position
how to isolate which muscle is affected
move starting posittion of eye
- If starting in an abducting (lateral) position (right eye)
- Then ask to move eye up and down- rectus muscles more dominant action
- Left eye will be testing the rectus muscles
- then test elevation and depression
Recti muscles are main …….. (SR) and ………. (IR) of the eye when the eyeball is starting in the ………… positition
Recti muscles are main elevator (SR) and depressor (IR) of the eye when the eyeball is starting in the lateral position
Oblique muscles are main …….. (IO) and ………. (SO) of the eye when the eyeball is starting in the ………… position
Oblique muscles are main elevator (IO) and depressor (SO) of the eye when the eyeball is starting in the medial position
Ocular misalignment
strabismus
strabismus is common in
children
strabismus in children
- (congenital or develop in infancy)
- Exact cause not known
- Cover eye/ different lenses
steabismus in adults
- acquired due to pathology or disease involving a number of different structures
- NMJ- e.g. myasthenia gravis)
- Nerve supplying the muscles (CNIII- oculomotor, IV trochlear, VI abducens)
strabismus and how cranial nevres can be affected
- Vasculopathic (microvascular ischaemia- diabetes, hypertension)
- Physical compression e.g. tumour or aneurysm (III)
- Raised intracranial pressure
CNIII - oculomotor innervates
- all extra ocular muscles (except LR and SO)
- muscles of the eyelid (LPS)
- sphincter pupillae muscle
how ill a CNIII - oculomotor nerve lesion present
Down and out bitches
Vasculopathic (microvascular) lesion of CNIII - oculomotornerve
e. g. caused by diabetes and hypertension
- down and out
- pupil will be spared
compressive lesion (raised ICP, tumour, posteiror communicating artery aneurysm) on CNIII - oculomotor nerve
- down and out
- pupil involved (ma be involved first before other components involved)
CN IV trochlear innervates
superior oblique muscle only
- intort
- depress
- abduct eye
how will CN IV trochlear nerve lesion present
- EXTORTED
- slighly elevated
- adducted
signs of trochlear nerve lesion
Head tilt- to compensate extortion
worsening diplopia (on downward gaze) especially looking down and medially e.g. walking down stairs or reading
- SO is main depressor of the eyeball when in adduction*
- SO weak- this action affected*
CN VI abducens nerve innervates
lateral rectus
CN VI abducens nerve lesion will present with
eye held in adduction–> horizontal diplopia
- unopposed pull of medial rectus muscle
- unable to abduct the eyes on affected side
