Diseases of the Orbit

What is the function of the orbit?

Globe protection

What are the orbital contents?

Nerves and blood vessels

Extraocualr muscles and orbital fat

Third eyelid and gland

Lacrimal gland

Zygomatic salivary gland

Skull bones: open or closed

What structures are in close proximity to the orbit?

Tooth roots, oral and nasal cavities

What are the types of orbits?

Open or closed

What do changes in orbital volume affect?

Globe position

What are the steps of an orbital exam?

Visual inspection for symmetry

Palpation of orbital rim

Retropulsion of globes

Nasal air flow

Ability to open mouth

Oral exam caudal to last upper molar

What are signs of orbital disease?

Exophthalmos and Elevated third eyelid are most important

Also, enophthalmos, strabismus, pain on palpation, pain on opening mouth, exposure keratitis

What is exophthalmos?

Normal sized globe that is displaced anteriorly due to increased orbital volume

What are the causes of exophthalmos

Neoplasia, abscess/cellulitis are main causes

Also, hemorrhage, vascular anomaly, mucocele, cyst, myositis

What do you need to differentiate exophthalmos from?

Conformation exophthalmos (normal in pugs)

Buphthamos (globe will be enlarged)

Proptosis

What is buphthamos?

Enlargement of globe

How can you different buphthamos from exophthalmos?

Blindness in buphthamos

IOP is increased in buphthamos

What is enophthalmos?

Normal sized globe displaced posteriorly due to globe retraction, decreased orbital volume, or pressure anterior to equator of the globe

What are causes of enophthalmos?

Pain, Horners syndrome mainly

Also, muscle wasting, loss of orbital fat, orbital fracture, dehydration, extraocular muscle fibrosis, adnexal neoplasia

What do you need to differentiate enophthalmos from?

Phthisis bulbi

Microphthalmos

What is phthisis bulbi?

Post-inflammatory shrinkage of globe

What images are good for orbital disease diagnostics?

Dental radiographs

Orbital/ocular ultrasound

CT

MRI

What are some samples you can get from an orbital sampling?

FNA and cytology

Culture and susceptibility

Biopsy and histopathology

T/F skull radiographs require anesthesia?

True

What are skull radiographs useful for?

Bony lysis or proliferation

Sinus or nasal disease

Radio-dense foreign bodies

What can dental radiographs tell you?

Tooth root abscesses

T/F skull radiographs are very helpful for the orbit?

False

T/F you should use topical anesthetic to ultrasoudn?

True

Where do you place the ultrasound probe for the orbit?

On the cornea

What probe do you use for an ocular ultrasound?

10-13 MHz

What probe do you use for orbital ultrasound?

7.5 MHz probe or a doppler

What are ultrasounds useful for diganosis?

Cysts and abscesses

Vascular anomalies

Foreign bodies

T/F CT requires anesthesia?

True

What are CT useful for?

3D orbital imaging

Examination of bony details like an orbital fracture or bony lysis

T/F MRI requires anesthesia?

True

What are MRIs useful for?

3D orbital imaging

Detailed soft tissue study

What is a contraindication for an MRI?

Metallic foreign body

What are the two techniques for an orbital FNA?

Blind or with ultrasound/CT

What are the approaches to an orbital FNA?

Transconjunctival adjacent to globe

Through skin posterior to orbital ligament

Oral caudal to last molar tooth

What are some orbital abnormalities/diseases?

Orbital cellulitis/abscess

Orbital neoplasia

Ocular proptosis

Also, congenital problem, salivary mucocele or cyst, masticatory or EO muscle myositis

What is the signalment for orbital cellulitis/abscess?

Young animal with acute onset

What are the C/S of orbital cellulitis/abscess?

Fever, exophthalmos, pain, elevated third eyelid

What is orbital cellulitis/abscess?

Inflammation of the orbital tissues ± abscess

How do you confirm an orbital abscess?

Imaging

How do you treat abscess in the orbit?

Establish drainage

Remove nidus

Medical therapy with antibiotics, systemic NSAID, ocular lubrication, soft food

How can you drain the orbit?

1. Incise oral mucosa caudal to last upper molar w/ #15 bard-parker blade

2. Insert closed hemostat, advance slowly, then open

3. Collect samples

4. Leave open to drain (drain by gravity)

What antibiotics are good for orbital abscesses?

AmoxiClav (Clavamox)

Cefpodoxime (Simplicef)

Enrofloxain (Baytril)

When would you do a temporary tarsorrhaphy (suture eye closed)?

If abscess is very severe and eye might dry out and lubrication alone will not help

What are the origins of orbital neoplasia?

Primary from any orbital tissue

Invasion of adjacent structures

Metastasis from distant site

What is the signalment for orbital neoplasia?

Older patients with slowly progressive changes

What are the clinical findings of orbital neoplasia?

Not painful

Unilateral exophthalmos

Elevated third eyelid

Decreased retropulsion

How do you diagnose orbital neoplasia?

Complete physical

Thoracic radiographs (met check)

Ultrasound, CT/MRI

FNA

How do you treat an orbital neoplasia?

Orbitotomy and mass excision (eferral)

Exenteration and chemo

Euthanasia if advanced disease

What is the prognosis for orbital neoplasia?

Guarded to poor with survival time increasing with early diagnosis and surgical therapy

Worse in cats than dogs

What is ocular proptosis?

Globe moves anterior and eyelids become trapped behind equator

What causes an ocularr proptosis?

Trauma, important to assess non ocular injuries too

T/F ocular proptosis in an emergency?

True

How do you treat ocular proptosis?

Enucleate or surgically reposition

What are the 3 enucleation criteria for an ocular proptosis?

3 or more EOMs torn

Optic nerve transected

Globe ruptured

What medications can you use for ocular proptosis treatment?

oral antibiotic

Oral NSAID

If corneal ulcer add a topical antibiotic and atropine

What do you include with the ocular proptosis treatment?

Medications

E-Collar

Keep area clean

Rechecks to remove sutures in 2-3 weeks