Lecture Two: The Orbit

Protect the globe

What is the function of the orbit?

Open

Do dogs and cats have an opened or closed orbit?

Closed

Do horses have an open or closed orbit?

Bone, masticatory muscles, medial Pterygoid muscle, zygomatic salivary gland

What is the composition of the orbit and supporting tissues?

Frontal, lacrimal, zygomatic

Which bones make up the orbit?

Supraorbital ligament

Carnivores have an open orbit. What is the supporting structure in this open area?

Fusion of zygomatic and frontal bones

What makes the orbit of herbivores closed?

Maxillary, ophthalmic, Supraorbital, ethmoidal

What are some vessels that run through the orbit?

CN III, IV, V, VI, maxillary, supraorbital

What are some nerves that run through the orbit?

Oral and nasal cavities, paranasal sinuses, tooth roots

What adjacent areas have an influence on the orbit?

Exophthalmos

Globe is positioned outward

Enopthalmos

Globe is positioned inward

Strabismus

Abnormal alignment of the eyes. Googly eyes

• Ophtho exam

• oral exam

• nasal discharge

• hemorrhage

When examining the globe, what are some exams/things you will check?

Rads, US, CT

What are some advanced imaging you would do to examine the orbit?

CBC, chem, FNA cytology, biopsy, C&S

What are some other diagnostics you would do if you suspect a problem with the orbit?

Cellulitis

Another word for orbital abscess

Acute onset, rapid, often young stick chewers

What is the typical signalement of cellulitis (orbital abscess)?

Sterile, bacteria, fungi

What are the causes of orbital abscesses/ cellulitis?

Foreign body, sinusitis, periodontitis, panophthalmitis

What are the sources of orbital abscesses/ cellulitis?

Unilateral exophthalmos, exposure keratitis, elevated third eyelid, pain upon opening mouth

What are the clinical signs of an orbital abscess?

Opening mouth

In orbital abscess cellulitis the patient is usually painful when _____________

Febrile, leukocytosis, draining tract, dental disease, or tooth root abscess on dental exam

What are the diagnostic findings of a patient with an orbital abscess cellulitis?

Systemic Ab, NSAIDS and pain medication, soft food +/- establishing drainage and temporary tarsorrhaphy

How do you treat orbital abscess cellulitis?

Older, slowly progressive

What is the common signalment for orbital neoplasia?

Primary (osteosarcoma, meningioma, fibrosarcoma)

Do dogs usually get primary or secondary orbital neoplasia?

Secondary (squamous cell carcinoma, melanoma, lymphoma)

Do cats usually get primary or secondary orbital neoplasia?

Osteosarcoma, meningioma, fibrosarcoma

What are the common orbital neoplasia's of dogs?

Squamous cell carcinoma, melanoma, lymphoma

What are the common orbital neoplasias of cats?

Malignant

Are orbital tumors usually benign or malignant?

Unilateral exophthalmos, endophthalmos, strabismus, exposure keratitis, +/- indentation of posterior globe on fundic exam

What are some common signs of orbital neoplasia?

No!!

Are orbital neoplasias usually painful?

yes

Do you still need to do an oral exam for an orbital neoplasia?

Afebrile, normal bloodwork unless metastatic

orbital neoplasia BW?

• Stage, Grade (systemic evaluation, sample the mass)

• Complete excision, exenteration, radiation alone, chemotherapy, or a combination.

orbital neoplasia tx?

Usually acute presentation.

Orbital hematoma, fracture, foreign body (usually unilateral), SQ emphysema, crepitus with sinus involvement

What are some common findings with orbital trauma?

Proptosis

Eyeball protrudes from normal position. Eyelids trapped behind the equator

Yes!!

Is proptosis an ophthalmic emergency?

Acute glaucoma, anterior lens luxation, corneal rupture, deep rupture, proptosis

What are some ophthalmic emergencies?

Check PLR

What should you do with a proptosis patient (may not help prognosis)?

Extraocular muscles affected, intraocular signs

What will determine the prognosis for a proptosis patient?

• Doliocephalic (long nose)

• cats

What animals have the worse proptosis prognosis usually?

• 3 or more extraocular muscles torn

• optic nerve transected

• globe ruptured

What would indicate enucleation in a proptosis patient?

Hamsters

What exotic patients are prone to getting proptosis?

Lubricate cornea, stabilize patient

What is the emergency treatment of proptosis?

Lateral canthotomy, temporary tarsorrhaphy

Besides enucleation, what other surgical procedures may be indicated in proptosis?

Topical Ab, topical cycloplegic, Systemic Ab, systemic steroids, e collar

How do you medically treat proptosis?

27%, 0%

Dogs with proptosis have about a _________ chance of getting vision back, whereas cats have another _________

Medial canthoplasty (dec eyelid opening, limit future prolapse, correct medial entropion, correct nasal fold irritation)

How can you prevent proptosis?