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Binocular vision 2 > Mechanical limitation - TED and orbital fractures > Flashcards

Mechanical limitation - TED and orbital fractures Flashcards

1
Q

what type of disease is thyroid eye disease and what is it due to

A
  • TED Idiopathic autoimmune disease (pathogenesis is still uncertain)
  • due to the dysfunction of the thyroid gland itself, using too much of the thyroid stimulating hormone
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2
Q

how does cigarette smoking increase the likelihood of TED

A

by the nicotine when the cigarette is not filtered and goes straight to the eye

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3
Q

what are the 2 identifiable phases of TED

A
  • Acute / subacute

- Cicatrical “inactive”

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4
Q

what happens in the acute/subacute phase of TED
what do the symptoms reflect
list the 3 parts of the eye affected by the inflammation
what management stage is this

A
  • Inflammatory stage

Symptoms reflecting intensity of inflammatory reaction

  • Ocular (eyelids, orbital tissues & globe)
  • Optic nerve
  • Extraocular muscles
    Does not occur in every case
  • Medical management stage
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5
Q

what causes the acute/subacute phase of TED to have inflammatory and how long does this tend to last for

A

from the hyper/hypo thyroidism
when the antigens are affecting all the muscles and all the structures of the orbit, this causes signs and symptoms to occur
then after 1-2 years it blows itself out

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6
Q

what happens in the Cicatrical “inactive” phase of TED

A
  • Fibrosis and secondary muscle contraction
  • Patient’s appearance improves
  • Reduction in sight-threatening optic neuropathy
  • “Burn – out”

some of the swelling resolves but the muscles become fibrotic so it makes it difficult to move the eyes

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7
Q

how long does a patient with TED have to wait to get treatment

A

have to wait years to get treatment = debilitating for patients

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8
Q

list the 8 ocular signs of TED

A
  • Upper eyelid retraction
    Sympathetic overactivity with overaction of Muller’s muscle
    Increased innervation to SR and elevator muscle
  • Lid lag on down gaze
  • Proptosis (exophthalmos)
    Axial and usually symmetrical, although can be asymmetric
    Not correlated with disease severity
- Mechanical restriction of ocular motility 
duction = version
Progressive strabismus (caused by fibrosis of muscle)
  • Compressive optic neuropathy
  • Chemosis (swelling of conjunctiva)
  • Conjunctival injection of rectus muscle insertions
  • Periorbital oedema
    Raised intraorbital pressure
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9
Q

what 2 things causes the upper eye lid retraction in TED

A
  • Sympathetic overactivity with overaction of Muller’s muscle
  • Increased innervation to SR and elevator muscle
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10
Q

how will you see that ductions = versions i.e. that TED is mechanical

A
  • in OM
  • if you cover one eye and it doesn’t move further with duction movement
  • it is the same with both eyes open/versions
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11
Q

what 6 signs will show you that thee is optic nerve involvement in TED
and what you should do if these are seen

A
  • Loss of VA
    Corneal exposure, refractive changes or compressive optic neuropathy
  • Loss of vision from ON compression
  • Subjective change in colour vision
  • No relative afferent pupil defect in symmetrical bilateral compressive optic neuropathy
  • Mild or no optic disc swelling
  • Visual field defect
  • urgent referral
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12
Q

when will a pupil defect only be seen in TED

A

only in unilateral cases

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13
Q

how fast can someone lose their vision in an extreme case of TED and what must be done if this is seen

A
  • px can go from 6/4 to HM in 24 hours of onset

- people who have visual loss have to have surgery done immediately

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14
Q

list the 3 main symptoms of TED

A
  • Discomfort
    Drying of corneal epithelium from proptosis, upper lid retraction, poor blink pattern or reduced Bell’s phenomenon
  • Diplopia
  • Loss of vision
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15
Q

what causes the discomfort in TED

A
  • Drying of corneal epithelium from proptosis
  • upper lid retraction
  • poor blink pattern or reduced Bell’s phenomenon

px complains that eyes are gritty due to incomplete blinking so need to give lots of lubricants

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16
Q

what causes the diplopia in TED

A

enlarged EOMs causing limitations of the eye in the orbit

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17
Q

what 3 things is involved in the pathology and natural history of TED

A
  • Enlargement of the bellies of the EOM in the early stage (causes ON to stretch)
    Tendon sheaths are not involved at their insertions
  • Inflammation in EOM causes fibrosis leading to limited ocular motility
  • Increased soft tissue volume causes proptosis

(as the orbit is a fixed size, there is nowhere for muscle to go but out, causing it to stretch and pull the ON and stetting muscles also causes in to squash the ON)

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18
Q

what causes the strabismus in TED and what deviations in seen as a result

A
  • Typically IR fibrosis causes : hypo deviation
  • MR fibrosis leads to an eso deviation (as its too tight = restricting abduction)
  • Often see an eso and hypo deviation together = downwardly depressed and convergent
  • Can be either manifest of latent
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19
Q

which is the most affected EOM in TED and why is this

A

the IR
because when the muscles get restricted, they don’t all get restricted by the same amount
the inflammation is fluid based, going into the muscle bellie and we spend most of our time healing
so gravity alone dictates that the most defective

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20
Q

what happens if the TED affects each individual muscle symmetrically

A

there will be a symmetrical limitation = the eye is fixed in pp and is not very symptomatic

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21
Q

which 3 EOMs are affected in TED from most to least likely

A

IR
MR
SR

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22
Q

with the IR muscle being affected in TED:
where is the gaze defect and what does this result in
which gaze position is the defect maximum in
what will be the AHP and why

A
  • Upgaze defect = hypo deviation (most common defect of OM)
  • Maximum in elevation +/- small degree of excyclotorsion
  • Abnormal head posture – chin elevation for comfort (as the IR is constantly trying to relax but can’t allow the eye to come up)
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23
Q

with the MR muscle being affected in TED, where is the gaze defect and what does this result in

A

Abduction defect therefore eso deviation

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24
Q

with the SR muscle being affected in TED:
where is the gaze defect
which gaze position is the gaze defect maximum in

A
  • Depression defect

- Usually max in abduction and adduction

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25
Q

what is best to use for managing the squint in TED and why

A

fresnels are best to give instead of built in prisms as the squint in TED can change from day to day, or the size and direction of the squint can change on a monthly basis

you may also want to give some form of occlusion so they can manage their symptoms from day to day

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26
Q

when should you refer a px with TED and why is it important to refer at this time
what 4 reasons will you refer for

A

Suspected TED, early referral important because medical treatment most effective in active phase

Corneal exposure
Strabismus
Optic nerve compression
Poor cosmesis

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27
Q

list the 4 medical management options for a px with TED

A
  • Topical therapy (mild cases)
  • *High – dose steroids (moderate-severe cases)
  • *Orbital Radiotherapy treatment
  • Immunosuppressive therapy
28
Q

what is the conservative medical management option for TED
what are these in the form of
what are they useful for and why
what else may the patient need to do in addition to this

A

Topical therapy

  • artificial tears and decongestants
  • useful for conjunctival injection and chemosis
  • because patients often have very sore and red eyes
  • may need to tape eyes closed at night

this is because after 2 years the TED inflammation period that they have burns itself out, but does not resolve 100% e.g. proptosis, restriction of the eye movements etc is still there and topical medication is to prevent the symptoms of this getting worse

29
Q

other than the conventional topical therapy management, what are the 3 other medical managements of TED used in order, why are these used and what is each one used for

A

used for the preservation of sight as this is the priority reason for this medical management

  • Initially high-dose steroids
    reduce inflammation and thereby reduce the pressure on the optic nerve
  • Radiotherapy treatment
    Early stages of disease
  • Immunosuppressive therapy
    Improve congestive changes
30
Q

what reduces the effectiveness of all the medical managements of TED

A

effectiveness is reduced in all patients who smoke

so must ask patients to stop smoking if taking these drugs

31
Q

what are the 3 different surgical management options for a patient with TED
list them in order of what you will do first and then what after that

A

1st Decompression surgery
2nd Strabismus surgery
3rd Lid surgery
May not need all 3 surgeries e.g. is someone has symmetrical TED and no diplopia = won’t bother doing strabismus surgery

32
Q

when is the only time you can so surgical treatment for TED

A

6-12 months AFTER the active phase of thyroid burns itself out (and that can take up to 2 years to burn out)

33
Q

what problem is the 1st Decompression surgery done for in TED and why
and what 2 things does it improve and by how much for each

A
  • Proptosis
  • as it reduces but does not resolve 100% so best way is to remove bones from the orbit
  • this surgery is done within 24hrs because of ON compression and done to both eyes as this tends to go to other eye
  • Cosmetic improvement (90%)
  • ON compression (5-10%)
34
Q

what type of strabismus surgery is done in TED and to which muscles
why is this done (give 2 reasons)

A
  • Recession
  • MR / IR
  • Improve OM caused by mechanical restriction (i.e. to free up the muscles by moving the muscles back)
  • Correct cosmetic defect
35
Q

wha 2 types of lid surgery can be done for TED

A
  • Blepharoplasty - lift lid and scrape out congested fat

- Lid-lengthening surgery (quite rare)

36
Q

how long does the TED run its course for

A

12-24 month period

37
Q

list the 7 poor prognostic factors of TED

A
  • Older age at onset (worse when older)
  • Rapid onset (severe cases worse when rapid)
  • Longer duration of active disease
  • Drop in VA during active phase
  • Male
  • Smoker
  • Diabetic (worse if theres other disorders)
38
Q

what does orbital injuries occur with

A

midface trauma

39
Q

what are the 2 possible aetiologies than can cause a orbital injury
what do both types result in

A
  • Blunt trauma e.g. fist, elbow, knee or as a result of being thrown against a hard surface e.g. road traffic accident
  • Caused by blunt trauma to orbits by objects of diameter
40
Q

which part of the orbit is easiest to fracture from a blunt trauma and why
which 2 are the hardest to fracture and why

A
  • a floor fracture
  • because its easiest and its weak and thin and it has a nerve running underneath
  • frontal bone is very difficult to fracture as its solid
  • ethmoid bone is hard to fracture as its cushioned by the sinus so it bounces back
41
Q

what 2 affects can trauma to the orbit cause

A
  • soft tissue injury

- bone injury - hydraulic pressure

42
Q

what does a soft tissue injury caused by a blunt trauma have no involvement of
what 2 things does it cause
what symptom may a patient initially experience and for how long
what may it be difficult to confirm with this

A
  • No involvement of orbital bones
  • Causes oedema and haemorrhage
  • May initial experience diplopia and restricted eye movements due to the swelling which settles over time
  • May be difficult to confirm any motility problems if severe swelling/bruising
43
Q

how can you tell if a patient has had a soft tissue injury or if they have TED from their presenting symptoms of double vision and reduced motility

A
  • you have to see the muscle from an x-ray and CT scan
  • watch their motility after 4-5 weeks to see if it has improved as thats when the swelling starts to reduce and it is more likely to be a fracture and less likely to be TED
44
Q

what is a bony injury from hydraulic pressure also called
what does it result from
what does it cause and where abouts

A
  • Called blow-out fracture
  • Resulting from increased hydraulic pressure within the orbit
  • Causes fractures of the orbital plates at their weakest points usually orbital floor with antecedent prolapse of orbital soft tissue (e.g. fat) and bone fragments gets stuck into the maxillary sinus
45
Q

which type of fracture is most common with a blow out fracture
what type of limitation is it and why
what 3 things can happen to the muscle
what else may these people suffer from from the blow out fracture
what a patient who has this unlikely to get again and who do you not see this problem with

A
  • Floor fracture most common type of fracture
  • This limitation is mechanical where the trapped tissue acts as a tether (remove portion of the muscle)
  • The muscles may be injured, transected or avulsed (take muscle from the bone)
  • They may also suffer from haemorrhage or peripheral nerve damage – weak inactive IR muscle
  • unlikely to get full motility again
  • not seen in children
46
Q

what difference does the paediatric group get from a blow out fracture
what age group does this occur in
why is this
what is this called and why

A
  • Often very little external signs of injury
    e. g. no conjunctival redness
  • Occurs
47
Q

which gaze directions does a child who has had a blow out fracture experience
and so which type of diplopia will they complain of and when won’t they complain of diplopia

A
  • limited in up and down gaze - as muscle is trapped
  • px complains in a change of vertical diplopia when they look up and switched when they look down
  • they won’t complain of diplopia in primary position/middle as they have BSV there
48
Q

what are the 3 main symptoms of a blow out fracture from most to least likely
when and why will they have each symptom

A
  • Diplopia (in adults and children)
    main symptom blow-out fracture, can occur soft tissue injury
    vertical diplopia
  • Pain
    on attempted eye movement in direction opposite site of fracture – trapped tissue
    or may have lack of pain = infra orbital anaesthesia
  • Reduced vision
    occasionally but eye not normally affected due to nature of injury e.g. can have scratch across cornea from time of injury
49
Q

list 7 signs of a blow out fracture

A
  • Limitation of ocular motility
  • Infraorbital anaesthesia
  • Enophthalmos - Sunken eye
  • Oedema and ecchymosis of the periorbital tissues – black eye
  • Epistaxis - nose bleed
  • Subcutaneous air
  • Dramatic eye closure
50
Q

list 4 things that can cause the limitation of ocular motility seen as a sign of a blow out fracture

A
  • oedema
  • entrapment of tissue
  • herniation of tissue
  • displacement of globe
51
Q

what is Infraorbital anaesthesia and what is it due to, seen as a sign of a blow out fracture

A
  • numbness of cheek and upper lid

- due to direct trauma to the maxillary branch of the trigeminal nerve which runs along the floor of the orbit

52
Q

what causes enophthalmos
what may happen to it over time
what does it indicate
seen as a sign of a blow out fracture

A
  • indicative of herniation of fat and orbital contents into maxillary sinus as the muscle causes the eye to move backwards
  • may increase with time, difficult to treat
  • indicates fat atrophy
53
Q

what 2 things is seen due to Oedema and ecchymosis of the periorbital tissue
seen as a sign of a blow out fracture

A
  • eye closure

- subconjunctival haemorrhage

54
Q

where does the Epistaxis - nose bleed occur, seen as a sign of a blow out fracture
and what should you advise the px not to do and why

A
  • on the affected side
  • should not sneeze or blow their nose
  • as this makes it worse as the air in the sinus ends up in the orbit
  • this means the eye will move and will be very painful as the air sits there
  • and can cause secondary damage to the fracture such as further damage to the optic nerve
55
Q

where is subcutaneous air found
what is it indicative of
what can be done to confirm the presence of this
seen as a sign of a orbital blow out fracture

A
  • accumulation of air in connective tissue spaces
  • indicative of floor or medial wall fracturecrepitus
  • noise produced by palpation around the orbit due to the presence of air bubbles
56
Q

when may a dramatic eye closure occur
what is advised with these patients
how serious is this
seen as a sign of a orbital blow out fracture

A
  • may occur if nose blown shortly after injury
  • advised not to blow nose or sneeze if possible
  • it is self limiting with resolution within 48hrs
57
Q

what are the 2 radiological investigations that can be done with a blow out fracture and give reasons as to why each one is done

A
  • X-ray
    may show fracture of floor will show any fracture of orbital rim
    if fracture is quite far back = can’t see on x-ray so CT scan is better for this
  • CT scan
    vital to determine site and size of floor fracture. Will also show any fat, blood in the maxillary sinus
58
Q

what 3 clinical investigations will you carry out on someone whose had a orbital blow out fracture and what you will see in each investigation to confirm that it is due to this

A
  • Observation of signs
    enophthalmos, abnormal ocular posture and facial asymmetry
  • Cover test
    often BSV in primary position hypo or hyperphoria
  • Ocular Movements
    diplopia (reversal vertical diplopia reverses in vertical gaze from up to down gaze)
    globe retraction may be seen on up gaze
    note any pain
59
Q

what should you base the observation of the restricted eye on and what should you not base it on, with someone who has had a blow out fracture

A
  • base it on the corneal reflections

- do not base it on the position of the eye in relation to the lid

60
Q

what is the field of BSV like for a px who has had a blow out fracture and hence what is the best treatment/management options for them
what in the field of BSV suggests this is a mechanical aetiology

A
  • they only have a tiny about of single vision and a slight movement causes diplopia and gets further apart the further the eye movement goes
  • occlusion or fresnel is best treatment
  • a squashed upper and lower field suggests it is mechanical
61
Q

when is repair indicated of a white-eye blow out fracture

how many % of observed cases of a blow out fracture requires no active intervention

A
  • Early repair of white-eye blow out # indicated – 2/3 days post injury
  • Up to 50% of observed cases require no active intervention
62
Q

when will you do surgical repair for a fracture and under what 4 conditions/signs will you decide to do surgery

A
  • Within 2 weeks of injury

Must have:

  • +ve force duction test (tissue is trapped)
  • CT evidence of tissue entrapment
  • enophthalmos of >3mm
  • orbital floor defects of greater than 50%
63
Q

what is the reason for doing surgery to repair a orbital fracture and how is it done

A

done to:

  • hold eye in place so it doesn’t fall into sinus
  • dont want infection of sinus coming up into orbit
  • use a vortex which are permeable
  • this allows the blood vessels to grow through
  • it acts as a sling and holds the eye in the right place

or
- can use an artificial bone which also had holes in it to allow the normal tissue structure to grow

64
Q

when will a strabismus surgery be necessary to do
which muscles will usually be operated
what is it difficult to do with this surgery
what must you be aware of when considering this surgery

for a px who has had a blow out fracture

A
  • May be necessary at a later date if diplopia does not resolve or patient is referred late
  • Usually operate on overacting muscles of the unaffected eye
  • Very difficult/impossible to improve eye movement in affected eye – poor results
  • Be aware of occupation + hobbies e.g. painter / snooker etc where they want single vision
65
Q

why is the over acting muscles of the unaffected eye recessed in someone who has had a orbital blow out fracture as opposed to the affected eye muscles being resected

A

there is no point in resecting because do not know how much of that muscle is still functioning and actually damaged
all you know is that something is not working as well as it should be

66
Q

when is surgery more effective to do with someone who has had a blow out fracture
and what may a px have to do if their diplopia persists

A
  • when done before fibrosis and scarring of tissue into the fracture site develop
  • may need to change employment, stop driving and give up or alter sporting activities if diplopia persists

Binocular vision 2 (20 decks)

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