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RUSVM SAM 2 > Orbit > Flashcards

Orbit Flashcards

1
Q

What do you call the supportive structure of the eye that contain the eyeball, extraocular muscles, fat, vessels, nerves, and fascia?

A

Periorbital cone

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2
Q

What sinuses surround the orbit?

A

Frontal and maxillary

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3
Q

Inflammation of what salivary gland can lead to displacement of the globe?

A

Zygomatic

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4
Q

What are the muscles of mastication?

A

Masseter
Temporalis
Pterygoid

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5
Q

What bony structure can compress inflamed orbital soft tissue causing severe pain?

A

Paramus of the mandible

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6
Q

Why do we avoid mouth gags in cats?

A

Risk of blindness

If mouth is opened to widely Ramus of manbidle compresses maxillary and carotid artery, reducing blood flow

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7
Q

What nerves exit the optic canal??

A

CN2 optic

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8
Q

Which nerves exit the orbital fissure?

A

CN III - oculomoror
CN IV - trochlear
CN V - ophthalmic branch of trigeminal
CN VI- abducens

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9
Q

What is cavernous sinus syndrome?

A

Venous sinus located near the orbital fissure that allows passage of ophthalmic nerves

Infection/inflammation/neoplasia/vascular disorders can disrupt nerve function leading to the following clinical signs..

External ophthalmoplegia 
Internal ophthalamoplegia  
Ptosis 
Reduced corneal and medial canthal sensation 
Reduced lateral canthal sensation
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10
Q

T/f: both cats and dogs have an orbital ligament that forms the boundary of the orbital rim

A

True

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11
Q

What features of the brachycephalic skull make them very susceptible to trauma related ocular diseases??

A

Relative to skull size, the orbital ligament spans a greater portion of the orbital rim in brachycephalic

Orbit is much shallower in brachycephalic

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12
Q

What species have closed orbital rims?

A

Cows, horses

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13
Q

What do you call abnormal protrusion of the eye from the orbit?

A

Exopthalamos

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14
Q

What are clinical signs associated with exopthalmos?

A 
Third eyelid protrusion 
Facial swelling 
Soft palate bulging 
Pain on opening mouth 
Fever
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15
Q

What are common causes of exopthalmos?

A

Orbital volume imbalance

Neoplasia *
Cellulitis/abscess *
Zygomatic salivary gland mucocele 
Masticatory muscle myositis 
Extraocular myositis 
Retrobulbar hemorrhage
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16
Q

What do you call an enlargement of the globe? What is the only cause of this>?

A

Buphthlamos

Glaucoma

17
Q

You have a dog with exophthalamos.. what will your diagnostic approach be?

A

Complete ophthalmic exam

  • test orbital symmetry
  • oral exam

CBC and Chem
Chest rads
Advanced imaging

Tissue sampling
-FNA or biopsy

18
Q

You discover your patient has as orbital neoplasia. What two treatment methods are there?

A

Globe sparing — palliative, radiation, surgical exploration, chemo

Globe removal

  • enucleation — removal of the eye
  • exenteration — removal of the eye and all orbital contents
19
Q

Your patient has orbital cellulitis/abscess. What two treatments are available ?

A

Medical
- NSAIDS and antibiotics

Surgical exploration/ drainage

20
Q

What do you call an abnormal recession of the eye within the orbit?

A

Enophthalamos

21
Q

Common clinical signs of enophthalamos?

A

Facial muscular loss
Third eyelid protrusion
Entropion

22
Q

What are three common mechanisms of enophthalamos ?

A

Orbital volume imbalance
Eg dehydration, emaciation, myopathies, space occupying lesion of anterior globe

Active globe retraction
Eg ocular pain — retractor bulbi muscle

Passive glob retraction
Eg horners syndrome — loss of sympathetic tone

23
Q

What do you call a congenitally small globe?

A

Microphthalamos

Seen in collies

24
Q

What do you call an aquired shrunken globe, usually from severe/chronic inflammation?

A

Phthisis bulbi

25
Q

What do you call a deviation of one or both eyes, so that both eyes are not directed at same object?

A

Strabismus

26
Q

Congenital causes of strabismus?

A

Congenital
- “normal” variation of brachycephalic

  • Siamese cats - convergent, abnormal visual processing
  • hydrocephalus— ventrolateral divergent, abnormal orbital volume
27
Q

Acquired causes of strabismus?

A

Mechanical or nervous dysfutnion of any rectus muscle
CN III - dorsal, ventral, medial rectus m and ventral oblique
CN IV - dorsal oblique
CN VI - retractor bulbi and lateral rectus

Imbalance in orbital volume

28
Q

What do you call an anterior displacement of the globe, such that the eyelids are caught behind the equator of the globe ?

What breed is this common in?

A

Proptosis

Brachycephalic breeds — involves minimal trauma

29
Q

T/F: brachycephalic have a better prognosis after proptosis than dolichocephalic dogs

A

True

30
Q

What features make a poor prognosis for proptosis?

A 
Cats 
Dolichocepalic 
> 3 extraocular muscles torn 
Ruptured eye 
Hyphens orbital fractures
31
Q

T/F: most dogs regain vision in the affected eye after proptosis

A

False

75-80% will be blind in the affected eye

32
Q

Triage for proptosis?

A

Lubricate corneal

  • triple antibiotic ointment or artificial tear ointment
  • e collar
  • minimize restraint
  • pain managment, sedation or anesthesia
33
Q

How is the eye put back into place after proptosis?

A

Horizontal mattress sutures in adjacent eyelids—> temporary toarsorrhaphy

Eye is pushed back into eye with dull end of scalpel blade,

Sutures tie lids together

+/-stents

  • IV tubing
  • red rubber catheters
  • rubber bands
34
Q

What maintenance therapy must you do following treatment of proptosis

A

Oral antibiotics for potential cellulitis/infection

If ulceration, give topical antibiotics and atropine

steroids or NSAID intra-op or post-op to reduce inflammation

Sutures stay in 3 weeks as cellulitis resolves

E collar!!

35
Q

What are complications from treatment of proptosis?

A

Corneal ulceration — misplaced suture

Loosening of suture

Strabismus — Torn musculature

KCS

Blindness

Recurrence
Need for enucleation

RUSVM SAM 2 (44 decks)

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