Ophtho2- Orbital Dz

protect the globe and it's associated structures

• Herbivores: closed orbit, laterally-oriented, wider binocular field, smaller total visual field
• Carnivores: open orbit- temporal orbital rim is comprised of orbital ligament, forward-oriented, smaller binocular field, wider total visual field, small blind spot to rear

globe, neurovascular bundle, fat, glands, extraocular muscles, fascia and periorbita

• b/w the periorbita and orbital wall
• provides cushion to protect the globe from shock and trauma

• lacrimal gland dorsally
• GNM ventromedially
• Harderian gland (cows, pigs, rabbits) at the base of the third eyelid
• zygomatic salivary gland fills the ventral floor of the orbit

zygomatic salivary gland

• retracts globe, only in animals (not birds)
• CN VI (abducens nerve)

• dorsal oblique- dorsomedial movement of globe; CN IV (trochlear nerve)
• ventral oblique- ventrolateral movement of globe; CN III (oculomotor nerve)

orbital apex; ventral oblique (arises from the medial orbital wall)

• [dorsal, ventral, medial, lateral] function antagonistically with opposing rectus muscles
• CN III (oculomotor nerve) for dorsal, ventral, and medial
• CN VI (abducens nerve) for lateral

• exophthalmos
• enophthalmos
• periocular swelling
• globe deviation
• elevation of the NM
• reduced retropulsion
• +/- pain on opening the mouth

• displaced rostrally within the orbit
• orbital neoplasia, orbital hemorrhage (trauma, coagulopathy), orbital cellulitis/ abscess, orbital mucocele (zygomatic salivary gland), myositis

buphthalmos (enlargement of the globe d/t chronic glaucoma); compare corneal diameters, retropulse both globes, skyline view for globe prominence beyond orbital rim, elevated third eyelid sometimes with exophthalmos and never with buphthalmos

• skull radiographs (least sensitive)
• CT scan (ideal for detecting bony changes)
• MRI (superior for soft tissue)
• ocular US (sensitive but not specific, neoplastic masses indent globe, inflammatory masses conform to globe)
• surgical exploratory (invasive)

• Acute- inflammatory
• Chronic- neoplasia

• Bilateral: systemic disease, myositis
• Unilateral: cellulitis, abscess, neoplasia

inflammatory causes; neoplasia

• microphthalmos: congenitally small globe
• phthisis bulbi: shrunken globe without vision associated with chronic intraocular disease

• dehydration
• cachexia
• atrophy of orbital fat (senile change, trauma)
• atrophy of retro-orbital muscles (myositis, denervation)
• secondary to ocular pain
• Horner's syndrome (b/c extraocular muscle cone is surrounded by muscle that has sympathetic innervation)

• Unilateral: neoplasia, post-traumatic orbital fat atrophy, ocular pain
• Bilateral: [systemic disease] dehydration, cachexia, muscle atrophy

• migrating FB- direct penetrating of orbit via soft palate
• hemtogenous spread from systemic infection
• extensions from adjacent periorbital inflammation or infection (tooth root abscess, sinusitis, zygomatic sialoadenitis)

• acute onset
• pain when you open the mouth
• unilateral elevation of the NM
• exophthalmos
• periocular swelling
• fever, leukocytosis
• +/- swelling behind last upper molar

• globe in close proximity with ramus of mandible
• opening the mouth changes the position of the ramus and compresses the orbital soft tissue structures

• broad-spectrum oral antibiotics
• NSAIDs or steroids
• lubricate cornea
• remove nidus of infection (tooth root abscess, etc)
• [not recommended] surgical drainage--> only if severe swelling behind molar

• aka masticatory muscle myositis, polymyositis
• acute swelling of the muscles of mastication

• exophthalmos
• swollen, firm muscles of mastication
• trismus (cannot open the mouth)
• +/- vision loss (d/t compression of the optic nerve by inflammed extraocular muscles)

• auto-antibodies to 2M muscle fibers (serum or muscle biopsy sample)
• muscle biopsy
• suggestive labwork: leukocytosis, eosinophilia, increased CK

• prednisone 0.5mg/kg PO BID for 2-4 weeks (tapered dose)
• may recur when therapy stopped

• acute, bilateral immune-mediated swelling, limited to the extraocular muscles
• no autoantibodies identified yet
• young golden retrievers

• signalement and presentation
• +/- MRI, ocular US
• treatment and prognosis is the same as eosinophilic myositis (immune suppression)

• unilateral
• non-painful exophthalmos
• enophthalmos in cats with orbital bony lysis
• slowly progressive
• non-responsive to antibiotics
• +/- vision loss
• posterior globe may be indented on imaging

• Dogs: usually primary ocular neoplasia, usually malignant
• Cats: usually secondary neoplasia, usually malignant
• Horses: usually secondary neoplasia (SCC most common), almost always malignant
• Cows: lymphoma, SCC most common

• osteosarcoma, rhabdomyosarcoma, meningioma, adenocarcinoma
• SCC
• lymphoma
• mast cell tumors

• surgery- exteneration
• chemotherapy
• radiation
• based on histopath diagnosis

• Grave- most are malignant!
• Except: SCC in cows and horses, exteneration may be curative is resection is complete and no metastatic disease

• common in brachycephalic dogs
• minimal trauma required for brachys
• severe trauma required for cats and other breeds of dogs
• make sure you address other injuries with trauma!

• acute exophthalmos with eyelid entrapment behind the globe
• severe chemosis
• subconjunctival hemorrhage
• blindness
• keratitis/ corneal ulcer
• hyphema

medial rectus muscle b/c it is the shortest muscle

• less than 2 extraocular muscles avulsed (look at position of globe to assess this)
• no lacerations or corneal disease
• peracute onset
• positive menace reflex
• pupil mid-sized or miotic
• consensual PLR present
• normal intra-ocular pressure

• mydriatic and non-responsive pupil
• absence of consensual PLR
• more than 2 extraocular muscles avulsed
• transection of the optic nerve
• corneal sclera laceration
• very low IOP
• hyphema

• to replace or not to replace? most end up blind so let owner's decide if they want to pay twice (will probably need to be removed later anyway)
• tarsorrhaphy
• +/- lateral canthotomy
• warm compresses
• systemic broad-spectrum antibiotics
• topical antibiotics
• anti-inflammatories
• e-collar
• soft food
• NO STEROIDS

• lateral or dorsolateral strabismus
• neutrophilic keratitis
• lagophthalmos
• KCS
• phthisis bulbi