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SA DX & TX II > Final Exam - Orbital Disease > Flashcards

Final Exam - Orbital Disease Flashcards

1
Q

what is the bony orbit?

A

part of the adnexa, conical bony structure that contains the eyeball & periorbital cone

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2
Q

what is buphthalmos?

A

literally means cows eye - refers to the abnormal enlargment of the eyeball

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3
Q

T/F: in buphthalmos, the size of the eyeball is abnormal, but the position is normal

A

TRUE

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4
Q

for our purpose, what is the one cause of buphthalmos for companion animals?

A

glaucoma

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5
Q

what is enophthalmos?

A

abnormal recession of the eye within the orbit

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6
Q

what is exophthalmos?

A

abnormal protrusion of the eye from the orbit with abnormal positioning & a normal globe size

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7
Q

what is horner’s syndrome?

A

sympathetic denervation to the eye & ocular adnexa with 4 classic clinical signs

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8
Q

what are the 4 classic signs of horner’s syndrome?

A

enophthalmos, ptosis, miosis, & protrusion of the 3rd eyelid

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9
Q

what is microphthalmos?

A

congenitally small & malformed globe

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10
Q

what is the oribital ligament?

A

ligamentous structure that forms the lateral boundary of the bony orbit in dogs & cats

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11
Q

what is the perioribital cone?

A

supportive cone-like structure that contains the eyeball, extraocular muscles, fat, vessels, nerves, & fascia that resides WITHIN THE ORBIT

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12
Q

what is phthisis bulbi?

A

acquired shrunken globe that is most often from severe or chronic inflammation

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13
Q

what is proptosis?

A

anterior displacement of the globe such that the eyelids are caught BEHIND THE EQUATOR OF THE GLOBE!!!

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14
Q

what is strabismus?

A

deviation of one or both eyes so that both eyes are not directed at the same object

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15
Q

T/F: the eyeball = eye = globe = all tissue within & including the cornea/sclera

A

TRUE

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16
Q

what is this anatomic structure?

A

periorbital cone

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17
Q

what sinuses are you worried about for a dog or cat with orbital disease?

A

frontal & maxillary sinuses - orbital disease can cause sinus disease & vice versa

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18
Q

why are you concerned about dental health in an animal with orbital disease?

A

dental disease often induces orbital or periorbital disease - especially the carnassial tooth (4th maxillary premolar)

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19
Q

how can the zygomatic salivary gland induce orbital disease?

A

inflammation of this tissue will lead to displacement of the globe

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20
Q

what muscles of mastication are involved with orbital inflammation?

A

masseter, temporalis, & pterygoid

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21
Q

how is the ramus of the mandible implicated in orbital disease?

A

movement compresses inflamed orbital soft tissues & can cause severe pain

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22
Q

why should you avoid using a mouth gag in cats?

A

risk of blindness! compresses carotid/maxillary arterial supply to the orbit

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23
Q

what is an alternative option that can be used instead of a mouth gag for a cat?

A

needle cap!

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24
Q

the optic canal houses what nerve?

A

CN II

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25
Q

the orbital fissure contains what nerves?

A

CN III, IV, V (ophthalmic), & VI

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26
Q

what are the significant foramina & fissures that may be affected in an animal with orbital disease?

A
  1. infraorbital foramen 2. optic canal 3. orbital fissure 4. rostral & caudal alar foramina 5. external acoustic meatus
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27
Q

between dogs & cats, which has a shorter orbital ligament? why?

A

both dogs & cats have an open orbit that is completed on the lateral boundary of the orbital rim by the orbital ligament - much shorter in cats given their orbit has more bony protection when compared to dogs

28
Q

how is the orbit & orbital ligament different in brachycephalic dogs? why is this important?

A

relative to skull size, the orbital ligament spans a greater portion of the orbital rim & the orbit is much shallower - brachycephalic animals will be more susceptible to ocular disease!!!

29
Q

what animals have a closed orbit? why os this important?

A

ruminants & horses - complete bony coverage at the orbital rim, so they have more protection from trauma relative to dogs & cats

30
Q

what is your most sensitive assessment for enophthalmos/exophthalmos?

A

dorsal view assessment!!!

31
Q

what is the purpose of retropulsion?

A

identifies mass effect within the orbital space

32
Q

what are your tests for examining orbital symmetry?

A

orbital palpation - for fractures, masses, pain dorsal view assessment - looking for enophthalmos & exophthalmos & retropulsion - looking for mass effect within the orbital space

33
Q

what are the 4 main disorders of globe position?

A
  1. exophthalmos 2. enophthalmos 3. strabismus 4. proptosis
34
Q

what are the 3 main disorders of globe size?

A
  1. buphthalmos 2. phthisis bulbi 3. microphthalmos
35
Q

what are the common clinical signs associated with exophthalmos?

A

3rd eyelid protrusion, facial swelling, soft palate bulging, pain when opening the mouth, & fever

36
Q

what is the most common mechanism of exophthalmos?

A

orbital volume imbalance

37
Q

what are some examples of causes of exophthalmos?

A

orbital neoplasia, orbital cellulitis/abscess, zygomatic salivary gland, mucocele, masticatory muscle myositis, extraocular myositis, & retrobulbar hemorrage

38
Q

what are the 2 most common conditions causing exophthalmos in dogs? what clinical signs are associated with each?

A

orbital neoplasia - often malignant, slowly progressive, & often non-painful & orbital cellulitis/abscess - seen in working dogs/stick chewers, acute onset, & often painful

39
Q

why do brachycephalic dogs have a normal exophthalmos?

A

they have it because of their shalow orbits

40
Q

how can lateral deviation of the globe present in orbital disease?

A

tumor involving the 3rd eyelid

41
Q

T/F: masses in the orbital space will change the position of the globe depending on their location

A

TRUE

42
Q

why are dogs with orbital cellulitis/abscesses so painful upon opening their mouth?

A

the soft tissues around the eye/masticatory muscles become inflamed, so movement of the ramus of the mandible becomes painful!!

43
Q

what are your 2 treatment options for exophthalmos due to orbital neoplasia?

A

glaobe sparing (palliative) - radiation, surgical exploration, & chemotherapy & globe removal (also palliative) - enucleation (removal of the eye) or exenteration (removal of the eye & all orbital contents)

44
Q

what are your 2 treatment options for exophthalmos due to orbital cellulitis/abscesses?

A

medical - anti-inflammatories (NSAID or steroids) & abx (broad spectrum) & surgical exploration and/or drainage

45
Q

why should you be careful when performing an enucleation in a cat?

A

optic chiasm can be affected by direct tension of the eye during enucleation can blind the normal eye!!!

46
Q

why should you be careful if establishing drainage for a dog with orbital cellulitis/abscess?

A

there are many vascular & nervous structures in this area & there is poor exposure

47
Q

what common clinical signs are seen in animals with enophthalmos?

A

facial muscle loss (uilateral or bilateral), 3rd eyelid protrusion, & entropion

48
Q

what are the 3 common mechanisms for enophthalmos?

A
  1. orbital volume imbalances 2. active globe retraction - skeletal muscle (retractor bulbi - CN VI) 3. passive globe retraction - involves smooth muscles of the periorbital cone, involving sympathetic system
49
Q

what are some common causes of enophthalmos due to orbital volume imbalances?

A

dehydration, emaciation/cachexia, myopathies, & space occupying lesions anterior to the globe

50
Q

how does ocular pain cause enophthalmos?

A

active retraction - active muscle tone!!!

51
Q

how does horner’s syndrome cause enophthalmos?

A

passive retraction due to loss of muscle tone!!!

52
Q

why does the 3rd eyelid protrude in an animal with horner’s syndrome?

A

loss of sympathetic tone!!!! passive protraction occurs

53
Q

what 2 conditions do you need to be careful to not confuse with enophthalmos?

A

don’t confuse with microphthalmia & phthisis bulbi - both are disorders of globe size

54
Q

what are congenital causes of strabismus?

A
  1. normal variation - brachycephalic dogs due to an abnormal orbital volume 2. siamese cats - convergent strabismus & abnormal visual processing 3. hydrocephalus - ventrolateral divergent strabismus due to abnormal orbital volume
55
Q

how does mechanical or nervous dysfunction cause acquired strabismus?

A

CN III - dorsal, ventral, medial rectus muscles, & ventral oblique (can cause a few different types of strabismus) CN IV - dorsal oblique & CN VI - retractor bulbi - can also be caused by imbalance of orbital volume

56
Q

T/F: in proptosis in brachycephalic dogs, minimial trauma is seen

A

TRUE

57
Q

what two things affect prognosis in an animal with a proptosed eye?

A

vision & globe retention

58
Q

how does vision affect prognosis of proptosed eyes?

A

> 75% are blinded due to optic nerve trauma - poor prognosis

59
Q

what factors of globe retention indicate a negative prognosis for a proptosed eye?

A

rupture of the eye, hyphema, orbital bone fracture, & poor owner compliance

60
Q

what is tarsorrhapy?

A

surgical procedure in which the eyelids are closed

61
Q

when is the tarsorrhapy removed for a proptosed eye?

A

only when orbital swelling has completely resolved (at least 2-3 weeks)

62
Q

how is a proptosed eye treated?

A

e-collar is placed & the eye is lubricated, proper pain management. sedation, & anesthesia is given with careful monitoring (vagal response can cause cardiac arrest or death) - place stay sutures & apply counter pressire to the eye with a clean, flat, blunt surface & then place a temporary partial tarsorrhapy at the meibomian glands & institute appropriate medical therapy

63
Q

what is the after care indicated for a proptosed eye?

A

e-collar!!!!! topical abx, topical atropine if uveitis/ulceration is present, oral abx, oral anti-inflammatories, & additional analgesia (tramadol)

64
Q

what type of strabismus is commonly seen as a complication after an eye has proptosed?

A

lateral strabismus - medial rectus muscle is the shortest & most easily torn muscle!

65
Q

why do we see corneal ulceration as a common complication following a proptosed eye correction?

A

corneal ulceration mostly from misplaced sutires

66
Q

what are some complications seen with proptosed eyes?

A

corneal ulceration, loosening of sutures, strabismus, KCS, blindness, repeated proptosis, & need for enucleation

SA DX & TX II (62 decks)

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