The Orbit Flashcards
What does the extraconal space consist of?
Zygomatic salivary gland Base of the third eyelid Orbital fat Maxillary artery Palatine nerve Infraorbital nerve Maxillary branch of CN V Parasympathetic pterygopalatine nerve and ganglion
What does the intraconal space consist of?
4 rectus muscles
2 oblique muscles
Retractor bulbi extraocular muscles
Periorbital fascial sheath
What are the clinical signs of extraconal orbital disease?
Non axial exophthalmos (strabismus)
Protrusion of the third eyelid
Extraocular muscle motility abnormalities
What are the signs of intraconal orbital disease?
Axial exophthalmos (no strabismus)
Minimal protrusion of the third eyelid
Extraocular muscle motility abnormalities
What is CT good for imaging in the orbit?
Bony structures
Dental/ sinus/ nasal cavity
Nasolacrimal disease
Metallic foreign body
What is MRI useful for in imaging the orbit?
Soft tissues Extraocular muscles Orbital fat Zygomatic salivary gland Brain Cranial nerves
Treatment for exposure keratopathy?
Lubricants
Medial/ lateral canthoplasty
What is an orbital arteriovenous fistula?
What is the clinical sign?
Rare congenital abnormal communication between the orbital arteries and veins
Pulsatile exophthalmos
What is the clinical sign of an orbital varice?
What is the treatment?
Intermittent exophthalmos, often worsens during exercise and can become permanent.
Coil embolization or exenteration
What is craniomandibular osteopathy?
Bilateral irregular nonneoplastic osseous proliferative disease of the cranium
What breeds are affected by craniomandibular osteopathy? What age? Clinical signs? Diagnosis Treatment?
WHWT
Scottish terrier
Cairn terrier
(Airedale)
Pain opening mouth
Not wanting head touched
Mandibular swelling/asymmetry of bony orbits
CT
Young dogs
None
What is the difference between exophthalmos and proptosis?
Proptosis has eyelid entrapment posterior to the equator of the globe, exophthalmos doesn’t.
Which extraocular muscle is the shortest and therefore the first to avulse in proptosis?
Medial rectus muscle
What is a good prognostic indicator for proptosis?
PLR and menace
If the sinuses are involved in a facial fracture (‘open fracture’) what medication should be given to the patient?
Broad spectrum ABs
What is the maximum time you should leave a facial fracture (due to fibrosis)?
5-7days
Which imaging modality is best for looking for organic foreign bodies?
MRI
Where in the orbit would you find a zygomatic mucocoele (sialocoele) on u/s?
What is the best imaging to perform for these?
Centrally
MRI
What are the treatment options for a zygomatic mucocoele (sialocoele)?
Resected with the gland
Drainage of the pterygopalatine fossa
What can orbital cellulitis and abscessation lead do?
Meningoencephalitis
Where is the pterygopalatine fossa?
Behind the last maxillary molar
What is masticatory muscle myositis?
An immune mediated disorder affecting muscles innervated by the mandibular branch of CN V and containing type 2M myofibres
Which muscles are affected my MMM?
Temporal
Masseter
Ptyerygoid
What ocular signs are seen with MMM?
Acute?
Chronic
Acute; Exophthalmos, TEL protrusion
Chronic; Enophthalmos (due to fibrosis)
How is MMM diagnosed (2 ways)?
Serum antibodies to type 2M myofibrils
Biopsy of the temporalis muscle (muscle fibre degeneration + inflammation)
What is the treatment for MMM?
Immunosuppressive doses of preds until resolution of CS then slow tapering
+/- other immunosuppressants
Lubricants
Physio
What is extraocular polymyositis?
An immune mediated inflammatory myopathy affecting extraocular muscles in dogs.
What size of dogs are most commonly affected by MMM?
Large breed
What age/ sex is most commonly affected by extraocular polymyositis?
What breed?
Young entire females ~1yo
Golden retriever
What are the clinical signs of extraocular polymyositis?
How do you diagnose?
Bilateral symmetrical exophthalmos with NO TEL protrusion (360’ scleral show)
No pain, clinically well
Clinical signs
Thickening and hyperechoicity oh the EOMs
What is the treatment of extraocular polymyositis?
Immunosuppressive doses of preds/ other immunosuppressants
May need long term
What clinical signs does fibrosing extraocular muscle myosotis with restrictive strabismus cause?
What animals/ breed/ sex are affected?
Uni/bilateral ventral/ventromedial strabismus (esotropia)
Enophthalmos
Young dogs
Shar Pei
Irish Wolfhound
Akita
How do you diagnose fibrosing extraocular muscle myosotis?
How is it treated?
Biopsy- fibrosis and lymphocytic plasmacytic mononuclear cellular infiltration
Resecting the fibrotic muscle
What percentage of orbital tumours in dogs are malignant?
Cats?
Dogs- 75%
Cats- 88%
Are primary or secondary orbital tumours more common in dogs?
Cats?
Dogs- primary
Cats- secondary
What are the clinical signs of Feline restrictive orbital myofibroblastic sarcoma (FROMS)?
Age/ breed/ sex?
Insidious unilateral exophthalmos
Restriction of the globe and eyelid motility (lagophthalmos)
Thickening of the eyelids
Then other eye +/- orbital tissue affected
Middle to older age, no sex/ breed
How do you diagnose Feline restrictive orbital myofibroblastic sarcoma (FROMS)?
Treatment?
Biopsy (send off eye if remove)
No treatment - often PTS
What are dacryops?
What is the cause?
Cysts of lacrimal gland tissue
Trauma or developmental
