test 2: lecture 22 orbit Flashcards
The bony cavity that encloses the eyeball with its associated muscles,
blood vessels and nerves.
orbit
compare orbit between dog and horse
dog has incomplete orbital rim
horse have complete bony rim
what nerves come from optic foramen
optic nerve (CN2)
what nerves come from orbital fissure
occulomotor (3)
trochlear (4)
ophthamlic (5)
abducens (6)
what are the 7 extraocular muscles and what do they control
orbital ligament
The orbital ligament completes the dorsolateral portion of the orbit in the dog and cat and covers the —
lacrimal gland
what is red and pink?
medial pterygoid muscle
nasal cavity
what is orange and blue
zygomatic salivary gland
frontal sinus
endorbita (periorbita)
“cone” around the muscles and glands of the eye, blood vessels and optic nerve
4 major clinical signs of orbital disease
Exophthalmos- eye buldging
Globe deviation
Lack of retropulsion - can’t get globe to move
Fundus lesion of globe indentation (retrobulbar mass)
protrusion of the globe out of the orbit caused by an increase in orbital content).
exophthalmos
(buldging eye)
most frequent types of orbital disease
tumor
trauma
abscesses
inflammation/cellulitis
two uncommon causes of orbital disease
zygomatic cyst and mucocele
myositis
— are rare causes of orbital disease
vascular abnormalities (AV fistula, varices)
diagnostic approach to determine orbital disease
history
examine both eyes at a distance
palpate periorbital area
perform complete eye exam
examine oral cavity
extra testing can be FNA, imaging (CT/MRI, ultrasound, xray)
orbital fracture due to trauma is most frequent in —
horses
dorsal orbital rim and zygomatic arch
trauma to orbit in dogs is most common by
penetrating foreign body
through eye or through soft palate
Proptosis following blunt trauma is frequent in what type of dogs
brachycephalic
hit by car or dog fight
what to do in ophthalmic emergency due to trauma
Keep cornea lubricated!
Reposition eye as soon as patient is stabilized
Lateral canthotomy
Partial or complete tarsorrhaphy (stents)
Leave room medially for topical drugs.
stabilize and then wait and see
clinical signs of orbital abscess or inflammation
Orbital signs (Exophthalmos * Globe deviation * Lack of retropulsion* Fundus lesion of globe indentation)
Acute
Unilateral
Pyrexia (fever)
Submandibular adenomegaly
Pain on palpation
Pain on jaw manipulation
how to diagnose orbital abscess or inflammation
CBC
Imaging – ultrasound, CT, MRI
Skull radiographs not that useful
FNA (or drainage) + cytology + Anaerobic, aerobic, fungal culture
what can cause orbital abscess or inflammation
Foreign body
Wound
2ary to sinusitis (maxillary, frontal)
2ary to tooth root abscess
2ary to infection of zygomatic or lacrimal gl.
how to treat orbital abscess or inflammation
Systemic antibiotics for 14-21 days
Use AB directed against anaerobes (eg. amoxycilin + clavulanic acid)
Topical antibiotic/lubrication if cornea exposure and lagophthalmos
Systemic NSAIDs (NO STEROIDS)
Systemic opioids
clinical signs of orbital tumor
Slow progression in older animals Unilateral
Initially no pain
Exophthalmos (frequent) Enophthalmos (if tumor located rostral to globe)
Variable deviation of the globe
Limited to no retropulsion
Globe indentation (fundus)
Vision often retained (except if optic nerve or meningioma involvement)
Most orbital tumors are —
primary and malignant
how to treat orbital tumor
Orbitotomy: open orbit and take out tumor (if benign and visual).
Exenteration: clean everything out- leaving only bone (if malignant) ± chemotherapy ± radiotherapy.
clinical signs of zygomatic mucocele/cyst
Orbital swelling
Exophthalmos
3rd eyelid protrusion
Protrusion oral mucosa behind last molar
Painless
how to diagnose zygomatic mucocele/cyst
Imaging : U/S, CT, MRI
FNA: Honeylike liquid
how to treat zygomatic mucocle/cyst
Surgical excision by one of these 3 approaches:
* transconjunctival
* oral,
* lateral orbitotomy
extraocular polymyositis
inflammation of the 7 muscles that control movement of the eye
clinical signs of extraocular polymyositis
inflammation of muscles that move the eyeball
immune-mediated?
acute
bilateral
fever
anorexia
opening mouth is painful/limited
at later stage muscle fibrosis causes mild enophthalmos (eye shrunken in) and strabismus(eye in wrong direction)
what types of dogs get extraocular pilymyositis
golden retriever
what kind of dogs get eosinophilic myositis of the masticatory muscules
german shepherd, wimaraner
(golden retriever and lab)
clinical signs of eosinophilic myositis of the masticatory muscules
Inflammation involves temporal, pterygoid, masseter muscles.
immune-mediated?
acute
bilateral
fever
anorexia
jaw opening painful and limited
at later stage muscle fibrosis causes muscle atrophy and enophthalmos(eye shrunken in)
how to treat myositis
Immunosuppresive doses of corticosteroids systemically for 3-4 weeks
or
Azathioprine 1-2 mg/kg for 10-14 days then tapered off
used to treat extraocular polymyositis and eosinophilic myositis of the masticatory muscles
how to diagnose extraocular polymyositis vs eosinophilic myositis of the masticatory muscles
extraocular polymyositis: CT/MRI
eosinophilic myositis of the masticatory muscles: muscle biopsy, elevated CPK
remove the globe
enucleation
remove globe and soft tissue
exenteration
surgery to open orbit
orbitotomy
