NV - Neuromuscular Disorders I: Orbital Causes - Week 1 Flashcards
What age group does thyroid eye disease most commonly affect?
21-60
List 6 common causes of orbital disease.
Thyroid eye disease Neoplasia Inflammation/infection Cystic Vascular Trauma
Does inflammation count as a space-occupying lesion? Explain.
Yes, as the tissue swells, there is loss of space for EM movement
Forward and backward eyes are known as what?
Forward - proptosis
Backward - sunken or enophthalmos
List three ways an abnormal eye position can be identified.
Aperture 9-11mm -smaller - enophthalmos -larger-proptosis Lids at the limbus -regulates scleral visibility at the top/bottom Birds-eye view
Is superior lid overhang onto the limbus normal? What about inferior? Explain.
Yes, 1-1.5mm overhang is normal
Less for the inferior limbus/lid - due to gravity
What is scleral show and what does it suggest?
When the superior and/or inferior limbus are not cleared by the lids and suggests proptosis
With a case of scleral show, what should you look for?
Symmetry between the eyes
Can scleral show be normal or is it always indicative of some abnormality? Explain (5).
Can be normal for the lower lid
-in upgaze
-in high myopes (>8.00DS)
-in people with high basal sympathetic tone
Will be symmetric in primary gaze (within 0.5mm) - look for difference in lid position
Explain the association between high myopes and scleral show.
High myopes can have normal scleral show due to high axial length
When should you suspect proptosis with scleral show (2)?
If it is present at the superior margin with primary gaze
If there is asymmetry between the eyes (>0.5mm)
What five things should you consider and look for if you suspect proptosis with scleral show?
Look for asymmetry in birds-eye position
Consider eyelid position (11-1 o’clock)
Presence of lid lag
Consider the distance of the lid edge to crease
Consider fellow travellers - pupils, EOM, CNs etc
Which gaze has greater eyelid asymmetry if lid lag is present? What sign is presnet?
Downgaze
An S shaped lid can be seen
Explain the birds-eye view.
Observe the patient’s eye position (not just eyelid position) from above and checking if they are level with each other
Use the plane parallel to the forehead
Explain the side-view.
Measure the position of the eye as corneal apex to zygomatic arch
How can proptosis be quantified? Explain how this works.
Exophthamometers
Two slidable prisms are placed at the zygomatic arches of the patient
The corneal apex is aligned with a marking on each prism
Measured in mm
If you suspect proptosis, name one differential to consider and a cause for it.
Lid retraction caused by dorsal mid-brain syndrome
How does lid retraction tend to appear (2) and which gaze is restricted?
Superior scleral show and stare
Upgaze limitation - they cant look up
How would lid retraction appear on birds-eye and side view?
Normal and <20mm side view
How does eye position appear with lid retraction?
Downcaste appearance
What dissociation may be present on downgaze with lid retraction?
Light-Near pupil dissociation
Are EOM and eyelid function normal on downgaze with lid retraction?
Yes
What should you do if you suspect dorsal mid-brain syndrome (management)?
Prompt neurological referral
List five causes of dorsal mid-brain syndrome.
Tumour Stroke Infection Trauma MS
What infection can cause dorsal mid-brain syndrome?
Syphilis
What two symptoms should require extra caution if you suspect lid retraction?
Blur and mild double vision
List 5 things to do when evaluating ocular misalignment.
Quantify region of binocular single vision (red lens with prism alignment or M700 BSV test)
Examine saccades/pursuits
Determine if restriction to movement in cases of trauma
Check oculo-cephalic reflex
Check fellow travellers
Do eyes tend to have proptosis or enophthalmos following orbital trauma? Explain why.
Enophthalmos due to blow-out fracture
Why does limited EOM movement tend to occur with orbital trauma (excluding inflammation)?
Entrapment (tethered)
Describe the ZSBV test. What is it important for?
Measures zone of single binocular vision - a spot of light is followed as it moves. Button is pressed once if it is single and twice if double vision or marked blur
Measurement important for litigation and surgery
List two workup tests for limited EOM movement due to entrapment.
Diplopic H pattern
Tether test
-IOP increases >4mm with gaze if tethered
List three common signs of thyroid eye disease (concerning the eyelids).
Upper lid retraction with/without lid lag
Proptosis
EOM issues (inflammation/diplopia)
What does lid lag expose on down gaze?
Lid crease
Why does the lid margin appear S shaped on downgaze with lid lag?
Due to regional involvement
Where would you expect to see inflammation with thyroid eye disease?
Marked hyperaemia at the outer canthus over muscle insertion is typical in TED
Aside from inflammation, what else can cause EOM restriction in thyroid eye disease?
Orbital congestion
What IOP readings can be indicative of thyroid eye disease?
Increased IOP in the upgaze by >4mmHg
What kind of strabismus can thyroid eye disease swelling cause?
Incomitant
Why is there less scleral show in infants with orbital mass?
Smaller aperture - more resistance
What does red eye with proptosis indicate?
Exposure
What should you consider if there is asymmetric proptosis (4)?
Orbital mass by retropulsion
- mass is palpable
- consider vision changes
- DFE for retinal folds
How does the eyes move on palpation if there is orbital mass?
Away from the mass
What must you not miss if you suspect proptosis?
Dorsal mid-brain syndrome
- upgaze palsy
- lids close
What is the management for proptosis?
Ocular decompression
Describe how ocular decompression is carried out.
Intentionally breaking the orbital sinus bones to allow tissue to expand into that space, relieving pressure on nerves
