Orbital Diseases Flashcards
What is the normal canine and feline orbit like?
incomplete - orbital ligament completes it laterally and the floor is left open
- made up of bone, fat, muscle, nerves, blood vessels, and glands (salivary, lacrimal)
What other structures are close to the orbit in all domestic species?
- mouth
- nasal cavity
- ramus of mandible
- sinuses
all possible origins of disease
Orbit structures:
What does orbital position depend on?
visual fields
- horses = monocular, laterally placed orbits
- dogs, primates = binocular, more medial orbits
What is enophthalmos? What are 5 common causes?
sinking in of the globe
- ocular pain - retraction
- Horner’s syndrome - lack of sympathetic tone
- loss of orbital fat
- phthisis bulbi, microphthalmia
- end-stage extraocular muscle myositis or atrophy following severe cellulitis
What is exophthalmos? What are some causes?
protruding globe
- neoplasia
- abscess/cellulitis
- FB
- masticatory or extraocular muscle myositis
- salivary mucocele
- sialoadenitis
- trauma
- cysts
- vascular anomalies
What are the 3 origins of exophthalmos?
- intraconal - swelling within cone of muscles
- extraconal
- within the orbit, outside periorbita
How does intraconal exophthalmos present? What are the 2 major etiologies?
projection of the globe forward without elevation of the third eyelid
- extraocular muscle myositis - always bilateral, must be differentiated from more common abscesses
- optic nerve meningiomas
How does extraconal exophthalmos present? What are the 2 most common etiologies?
elevation of third eyelid and deviation of the globe (strabismus) depending on mass location —> most common!
- retrobulbar abscess/cellulitis
- orbital neoplasia
What are the 2 most common etiologies of orbital exophthalmos?
- masticatory muscle myositis
- zygomatic sialoadenitis/mucocele
(no bony wall = orbit issues)
What are 2 examples of nearby structures that can cause exophthalmos?
- tooth root infections (carnassials!)
- neoplasia migrated from nasal cavity, ear, mouth, or sinus (nasal adenocarcinoma)
Why is examining the orbit especially difficult? What needs to be assessed?
cannot see it - observe from above!
- eye/periorbita
- head and eye position
- eyelid closure
- third eye location
- symmetry
What is the most important aspect of examining the orbit? What else is also commonly done?
retropulse the globes
- perform vision tests, like a menace response, maze, and tracking
- perform tonometry*, Schirmer tear test, and fluorescein stain
- open mouth to assess pressure the ramus of the mandible is putting on the globe —> abscesses are much more painful!
What does orbital disease commonly look like? How can it be differentiated?
conjunctivitis
- third eyelid position
- retropulsion of the globe
How does orbital disease affect vision and intraocular pressure?
vision should be normal, there can rarely be some retinal detachment —-> meningioma can affect vision!
usually normal to slightly elevated
What does pain upon closure of the mouth indicate for orbital disease? What is commonly seen?
- abscess
- cellulitis
- FB
swollen/red behind last molar (may need anesthesia to observe)
Exophthalmos characteristics:
What medical treatments are recommended for orbital cellulitis?
- not commonly drained
- systemic broad-spectrum antibiotics for 2-3 weeks
- pain control with systemic NSAIDs
- IV fluids, supportive care until able to eat
- temporary tarsorrhaphy for a week to close eyelids and allow healing
In what species is proptosis most common? What is the most common cause?
brachycephalic breeds - better prognosis!
trauma - HBC, bite wounds, dog fights
What are 4 favorable prognostic factors associated with proptosis treatment?
- positive direct or consensual PLR
- brachycephalic
- short duration with vision intact (positive menace)
- normal posterior segment
can be replaced
What are 3 unfavorable prognostic factors associated with proptosis treatment?
- > 3 extraocular muscles avulsed - eye will be looking in the wrong direction and bruised
- hyphema
- corneal or scleral rupture
usually enucleated
Proptosis:
- bruised
- ulcers from exposure keratitis
- could be replaced, but unlikely to have vision
How is a salvageable proptosis treated? What followup treatments are needed?
reposition under general anesthesia ASAP, usually requiring a lateral canthotomy
- temporary tarsorrhaphy with stents, sutures remain for 1 week
- systemic antibiotics
- NSAIDs or steroids
What are 6 complications and long-term sequelae associated with proptosis?
- blindness - only 20% retain vision
- dry eye disease
- recurrent corneal ulcers
- sensory deficits of cornea
- lagophthalmos - poor blink
- strabismus - rupture of extraocular muscles, most likely medial rectus making them look laterally
