Fine needle aspirate or biopsy Can perform “blind” or with ultrasound/CT guidance Remember the anatomy Many very important structures! Approaches Transconjunctival adjacent to globe Through skin posterior to orbital ligament Oral Caudal to last molar tooth

The Orbit Flashcards by Palak Shah

Orbital Anatomy

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Orbital Exam

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the orbit (meekins)

Clinical Signs of Orbital Disease

• Exophthalmos
• Enophthalmos
• Strabismus
• Elevated third eyelid
• Pain on palpation of periorbital area
• Pain on opening mouth
• Exposure keratitis

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the orbit (meekins)

Exophthalmos

Normal sized globe displaced anteriorly/rostrally within the orbit
Due to increased orbital volume
Numerous causes
- Neoplasia, abscess/cellulitis, hemorrhage, vascular anomaly, mucocoele, cyst, myositis, etc.

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the orbit (meekins)

Important to differentiate exophthalmos from:

proptosis (an eye that is protruding outside the orbit, usually due to trauma)

exophthalmos (an eye that is pushed forward relative to its normal position, but is still in the orbit)

buphthalmos (an enlarged, glaucomatic globe)

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Enophthalmos

Normal sized globe displaced posteriorly/caudally within the orbit
Due to globe retraction, decreased orbital volume or pressure anterior to the equator of the globe
Numerous causes
- Pain, muscle wasting, loss of orbital fat, Horner’s syndrome, orbital fractures, dehydration, extraocular muscle fibrosis, adnexal neoplasia

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Important to differentiate enophthalmos from:

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Orbital Disease Diagnostic Tests

Minimum database
Imaging studies*
• Skull radiographs
• Dental radiographs
• Orbital/ocular ultrasound
• Computed tomography (CT)
• Magnetic resonance imaging (MRI)
Orbital sampling
• Fine needle aspirate and cytology
• Culture and sensitivity
• Biopsy and histopathology

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the orbit (meekins)

Skull Radiographs

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Ultrasound

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Computed Tomography (CT)

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Magnetic Resonance Imaging (MRI)

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Orbital Sampling

Fine needle aspirate or biopsy
Can perform “blind” or with ultrasound/CT guidance
Remember the anatomy
- Many very important structures!
Approaches
- Transconjunctival adjacent to globe
- Through skin posterior to orbital ligament
- Oral
  - Caudal to last molar tooth

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Orbital Abnormalities/Diseases

• Congenital abnormalities
• Orbital cellulitis/abscess
• Salivary mucocele or cyst
• Masticatory muscle myositis
• Orbital neoplasia
• Ocular proptosis

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Congenital Abnormalities

Microphthalmos
Divergent strabismus
- Exotropia
- Mainly brachycephalic dogs
- Usually no clinical significance
Convergent strabismus
- Esotropia
- Inherited in cats
  - Autosomal recessive
  - Primarily in Siamese

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the orbit (meekins)

Orbital Cellulitis/Abscess

what
signalment and history
clinical signs
exam

Inflammation of the orbital tissues +/- abscess
Signalment and history
• Young animal, acute onset, compatible history (“stick chewer”)
• Possibly hyporexic or decreased chewing/aversion to hard food
Clinical signs and findings
• Exophthalmos +/- lagophthalmos
• Elevated third eyelid
• Injected conjunctival and episcleral vessels
• Resistant to retropulsion +/- painful
• Pain on periorbital palpation, yelps when mouth opened!
• Febrile

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Orbital Abscess Treatment

Confirm abscess (imaging)
Establish drainage if accessible
- Incise oral mucosa caudal to last upper molar with #15 Bard-Parker blade
- Insert closed hemostat, advance slowly, then open
- Collect samples
  - Culture/sensitivity (aerobic & anaerobic) and cytology
- Leave open to drain
  - May not see a lot of drainage
Remove nidus, if present
- Ex. foreign body, tooth
Medical therapy
- Systemic antibiotics (often mixed aerobic & anaerobic)
  - Cephalosporins (cefpodoxime, Clavamox) & Enrofloxacin are good first choices
- Systemic NSAID for pain and inflammation
- Ocular lubrication
  - Can use broad spectrum antibiotic ointment (i.e. NeoPolyBac)
  - Temporary tarsorrhaphy?
- Soft food
Response to therapy is usually within 2-3 days
Prognosis is good

Salivary Mucocele/Cyst

Usually due to trauma
- Saliva leaks from zygomatic salivary gland, causing inflammation and tissue fibrosis
  - Results in an encapsulated ‘cyst’
Signs of orbital disease
- Exophthalmos and TEL elevation
- Minimally or non-painful
Distinguished from abscess or neoplasia by imaging and sample collection
- Aspiration of yellow, tenacious fluid
Treatment
- Surgical excision or drainage
- Some reports of sclerosing agent injection

the orbit (meekins)

Masticatory Muscle Myositis

Immune-mediated inflammation targeting temporalis, masseter, and pterygoid muscles
- Type 2M myofibers
Breed predisposition:
- Golden and Labrador Retrievers
- German Shepherds
- Weimeraners
Clinical signs:
- Acute onset bilateral exophthalmos, painful and restrictive jaw movements, fever, lethargy, anorexia
Diagnosis: 2M antibody test, compatible clinical signs
Treatment: systemic immunosuppression

the orbit (meekins)

Orbital Neoplasia

origin
signalment and history
clinical findings

Origin
• Primary from any orbital tissue
• Invasion from adjacent structures
• Metastasize from distant site
Signalment and history
• Generally older patients
• Slowly progressive changes
Clinical findings
• Unilateral exophthalmos
• Elevated third eyelid
• Decreased retropulsion
• Scleral indentation on fundic exam
• Usually NOT PAINFUL

the orbit (meekins)

Orbital Neoplasia

diagnostics
treatment
prognosis

Diagnostics
- Complete physical exam
- Thoracic radiographs (met check)
- Orbital ultrasound
- CT/MRI for lesion localization and surgical planning
- FNA/biopsy of lesion
Treatment
- Orbitotomy and mass excision (Referral)
- Exenteration or radical orbitectomy
  - +/- Radiation therapy and/or chemotherapy
  - Enucleation or exenteration may also be performed as a palliative measure
- Euthanasia if advanced disease
Prognosis
- Guarded to poor
- Survival time increases with early diagnosis and surgical therapy
  - Less than 1 year in dogs, ~ 1 month in cats

the orbit (meekins)

Exophthalmos Clues

think inflammatory if…
think neoplasia if…
if bilateral?

Think inflammatory disease…
• If younger animal
• If painful
• If rapid onset
• If febrile
Think neoplasia…
• If older animal
• If slow onset
If bilateral…think myositis or multicentric neoplasia (lymphosarcoma)
But not all patients read the textbooks!!

the orbit (meekins)

Ocular Proptosis

what
caused by…

Globe moves anterior and eyelids become “trapped” behind equator
- True ophthalmic emergency!!!
Caused by trauma
- HBC, dog fight, kicked by horse
- Degree of trauma needed to cause proptosis varies
  - Most common in brachycephalic dogs
    - Shallow orbit and large palpebral fissure
    - Minimal trauma needed (even exam restraint can be a cause!)
  - Prognosis very poor in horses, cats, and dolicocephalic dogs
    - Severe trauma necessary

the orbit (meekins)

Ocular Proptosis

Keys to management

Ocular lubricant & E-collar
- KY Jelly, artificial tears, eyewash, Vaseline, cooking oil, etc.
Complete physical exam – assess for other injuries
Complete eye exam
Decide whether to enucleate or surgically reposition eye
- 3 enucleation criteria:
  - 3 or more EOMs torn
  - Optic nerve transsected
  - Globe (cornea and/or sclera) ruptured

# the orbit (meekins) **_Ocular Proptosis Treatment_** * **_surgical?_**

Globe replacement * General anesthesia * Prep * Keep eye lubricated! * Carefully clip eyelid hair * Cleanse area with dilute betadine solution * ~1:50 dilution: 5 ml 5% betadine in 250 ml saline * Not betadine scrub or chlorhexidine – toxic to cornea

# the orbit (meekins) **_Ocular Proptosis Treatment_** * **_non-surgical?_**

* Medications • Oral antibiotic • Oral NSAID • Topical antibiotic • Topical atropine • Pain meds as needed * E-collar * Keep area clean * Rechecks • Remove sutures in 2-3 weeks • Staged removal?

# the orbit (meekins) **_Ocular Proptosis Treatment_** * **_when in doubt…_** * **_prognosis_**

* When in doubt, replace the globe • You can always take it out, but you can never put it back! * Prognosis • Good in general if brachycephalic and minor trauma • Guarded for vision with intraocular hemorrhage • Pupil size is not an indicator of prognosis • But if direct or consensual PLR present, prognosis is good • Vision prognosis varies (~20% have some vision) • Better prognosis for saving globe • Many owners value globe for cosmesis

Ocular Proptosis Complications • Complications/sequelae

* Blindness * Strabismus * Primarily _lateral_ strabismus * Lagophthalmos (inability to blink completely) * Exposure keratitis * Decreased corneal sensation * Keratoconjunctivitis sicca (dry eye disease) * Glaucoma or phthisis bulbi (if severe intraocular damage)

# the orbit (meekins) **_Ocular Proptosis Treatment_** * **_Keys to remember_**

* Assess and treat the whole animal * Keep eye moist! * Rapid globe replacement if possible * When in doubt, replace the globe!

# the orbit (meekins) **_Orbital Surgery_** * **_Enucleation (what)_**

* Surgical removal of globe, third eyelid & gland * +/- silicone orbital prosthesis

# the orbit (meekins) **_Orbital Surgery_** **_• Evisceration (what)_**

* Removal of intraocular contents and placement of a silicone prosthesis in corneo-scleral shell * Contraindicated in cases of neoplasia/infection

# the orbit (meekins) **_Orbital Surgery_** **_• Exenteration (what)_**

* Removal of globe and all orbital contents * Generally performed for orbital neoplasia

# the orbit (meekins) **_Transconjunctival Enucleation_**

# the orbit (meekins) **_Transpalpebral Enucleation_**

* **Indications: surface ocular infection or neoplasia** * Suture eyelids closed * Incise skin around lids and dissect down to sclera, then work posterior

Enucleation • Post-operative care

* Cold compress (ice pack) applied to surgery site * B-TID for 10-15 minutes if tolerated * Some bleeding from incision and ipsilateral nostril is expected * Systemic nonsteroidal anti-inflammatory drug and/or other analgesic medication * Elizabethan collar if needed (usually not in cats) * Suture removal in 2 weeks

Enucleation Post-op Complications

* Bleeding from incision * Expected for a few days after surgery * Keep dog in confined, easily cleaned space * Infection * Cyst formation * Uncommon but due to poor surgical technique * Incomplete removal of secretory tissue * Surgery is performed to remove remaining secretory tissue * Contralateral blindness * Excessive traction placed on optic nerve during surgery * Damage to optic chiasm * More common in cats (due to neuro-anatomy) * Blindness is usually irreversible * Avoid with gentle surgical practices!!!

# the orbit (meekins) **_Evisceration_** * **_technique_** * **_indication_**

Evisceration Post-operative Care

* Topical and oral antibiotic * Systemic NSAID +/- analgesics * E-collar * Can still develop ocular surface disease that requires future treatment! * Corneal ulcers * Keratoconjunctivitis sicca

# the orbit (meekins) **_Exenteration_** * **_indications_**

* Remove globe and all orbital soft tissues • VS. enucleation (fat/muscle left behind in orbit) • Transpalpebral approach • Routine skin closure * Used in cases of extensive neoplasia * Submit tissues for histopathology

**_Summary_** * *_• Clinical signs of orbital disease:_** * *_• Orbital inflammation?_** * *_• Orbital neoplasia?_** * *_• Ocular proptosis?_** * *_• Enucleation?_** * *_• Evisceration?_** * *_• Exenteration?_**

* Clinical signs of orbital disease: * **Exophthalmos** * **Third eyelid elevation** * Orbital inflammation **(abscess/cellulitis) occurs in young dogs, is acute & painful, and results in fever, leukocytosis** * Orbital neoplasia **occurs in older dogs, is non-painful and slowly progressive** * Ocular proptosis **is a true ophthalmic emergency** * **When in doubt, always attempt replacement with tarsorrhaphy** * Enucleation **involves complete removal of globe and adnexa** * Evisceration **is a cosmetic alternative to enucleation** * Exenteration **is necessary in cases of advanced orbital neoplasia**