Orbital Disease and Surgery Flashcards
describe the orbit
a conical cavity containing the eye and its supporting structures
incomplete in carnivores, completed laterally by the orbital ligament = don’t mush on when trying to get IOP because could falsely elevate
complete in herbivores
floor is always open!! soft tissue and floor structure infections/disease can present as orbital disease
describe the orbital exam
- facial, orbital, and globe symmetry
-look from the top!
-beyond this, only if suspect disease or all else ruled out - orbital rim palpation
- retropulsion of the globes
-globe can normally be retropulsed into orbit
-space-occupying masses create resistant to retropulsion - ocular motility:
-vestibulo-ocular (doll’s eye) reflex: physiological nystagmus
-positions of gaze
-forced duction: numb eye and try to move with forceps - nasal airflow: nasal tumors are common causes of orbital disease
- oral examination:
-restricted movement
-painful: typically inflammatory disease
-nonpainful: non-inflammatory disease
-evaluate pterygopalatine fossa: soft spot connection to orbit, can be inflamed or painful - plain film skull radiographs:
-general anesthesia
-difficult to interpret but useful for boney changes (lysis/proliferation), sinus disease, nasal disease, radiodense foreign bodies, rarely ST masses and cysts - dental rads: to ID tooth root abscesses
- orbital ultrasounds to guide FNA or biopsy
- CT or MRI more helpful advanced imaging modality
- aspiration cytology/biopsy and culture/sensitivity
-ultrasound or CT guided is much less risky! but may provide definitive diagnosis despite risks to important orbital structures - exploratory orbitotomy
describe enopthalmos (clinical sign of orbital disease)
enophthalmos: globe recessed into orbit, dif ddx:
-loss of sympathetic tone
-space occupying lesion anterior to globe equator, pushes globe back
-decrease in orbital volume: fat atrophy from age, dehydration, post-inflam muscle atrophy or fibrosis
-pain
- differentiate from:
-microphthalmos: congenitally small globe
-phthisis bulbi: atrophied globe
-assess corneal diameter: equal of enophtlamos, decreased with microphthalmos or phthisis bulbi
describe exophthalmos (clinical sign of orbital disease)
- protrusion of globe due to space-occupying lesion within orbit
- often associated with:
-lagophthalmos (inability to blink)
-strabismus: deviation of globe
-exposure keratitis
-increased scleral showing
-+/- TIL elevation - differentiate from buphthalmos (enlarged globe)
-assess from above
-retropulsion: resistance to retropulsion with exophthalmos
-assess corneal diameter: equal with exophthamos, increased with buphthalmos
what are other clinical signs of orbital disease?
- third eyelid elevation
- strabismus
- epiphora (tearing); due to NLD system obstruction
- vascular congestion:
-conjunctiva
-episclera
-retina
what are 4 signs of congenital orbital disease?
- microphthalmos
- cyclopia/synophthalmos: single eye, fused at midline, common in lambs due to maternal ingestion of veratrum californicum of day 14 of gestation
- convergent strabismus of siamese cats/esotropia: autosomal recessive
- divergent strabismus and/or conformation exophthalmos: usually in brachycephalic dogs; incidental
describe horner’s, a sign of acquired orbital disease
- horner’s syndrome: lesion of sympathetic innervation to orbit; r/o uveitis, corneal ulcer
-dogs: ptosis, miosis, enophthalmos, TIL elevation
-horse: like dogs but also with ipsilateral sweating and vascular hyperemia of face
-cow: like dog but also with ipsilateral dry nasal planum
-ddx: idiopathic (dogs, spontaneously resolves), intracranial or thoracic neoplasia, trauma (HBC, head, neck, chest trauma, brachial plexus root avulsion), OMI, cleaning external ear canal, orbital disease, guttural pouch dz in horses
-diagnosis:
-phenylephrine testing: adrenergic agonist
–can localize lesion
–postganglionic lesion: improvement in clinical signs within 5-30 min
-denervation hypersensitivity improve within 2-14 days
-if improve at all = confirm horner’s; how long it takes helps you localize where
workup: based on localization
-otic exam
-thoracic rads
-MRI
treatment:
-idiopathic often resolves
-treat underlying causes
describe secondary enophthalmos
- enophtalmos due to loss of orbital contents or disease of adjacent structures
-weight loss
-muscle atrophy
treatment:
-underlying cause
-secondary entropion, conjunctivitis
describe phthisis bulbi
- shrunken bulb
- secondary to chronic/severe inflammation, glaucoma
- damage to ciliary body decreases and eventually stops aqueous humor production
- differentiate from microphthalmos
describe orbital cellulitis/orbital abscess
- etiologies not often found
-can be foreign body
-or orbital extension from adjacent diseased tissue: tooth root abscess, sinus infection, sialoadenitis - clinical signs:
-typically acute onset
-third eyelid elevation
-exophthalmos: usually unilateral
-increases resistance to retropulsion
-+/- periorbital swelling
-HALLMARK: pain upon opening of mouth (screaming)
-swelling in the pterygopalatine fossa
-+/- fever and inflammatory leukogram - diagnostics:
-physical exam
-minimum database
-ultrasound
-CT/MRI
-FNA/biopsy
therapy:
-broad spectrum oral antibiotics with anaerobic coverage
-systemic NSAIDs
-symptomatic therapy for cornea (lubrication, antibiotics if ulcerated)
-remove nidus if present (tooth FB)
-+/- drainage via oral cavity: gen anesthesia, stab incision in pterygopalatine fossa (posterior to last molar), insert hemostats and open, DO NOT CLOSE; +/- obtain sample for bacterial C&S
describe extraocular polymyositis
- golden retreivers and younger dogs overrepresented
- immune mediated myositis of EOM
- clinical signs:
-bilateral exophthalmos (stressed look)
-may be painful when open mouth but nothing like abscess - diagnosis:
-US, CT, MRI (thickened EOM)
-definitive: muscle biopsy: lymphocytic - therapy: systemic immumosuppression
describe masticatory/eosinophilic myositis
- GSD and weimeraners overrep
- immune-mediated
- clinical signs:
-onset bilateral exophthalmos with TEL elevation (with recurrent attacks)
-swollen masticatory muscle with difficulty and pain upon opening the mouth
-+/- blindness if optic nerve involved
-enopthalmos with chronicity - diagnosis:
-elevated CK, eosinophilia, type 2M muscle fiber antibodies
-imaging
-definitive diagnosis via muscle (temporalis) biopsy - therapy: systemic immunosuppression
describe orbital neoplasia
clinical signs:
1. usually insidious onset, nonpainful unilateral exophthalmos
2. strabismus: deviation of globe axis
3. reduced motility of globe
4. +/- indentation of posterior eye wall
5. +/- blindness if optic nerve involved
usually middle-aged to older animals
etiologies:
1. primary: most common
-lacrimal gland/TEL gland adenoma/adenocarcinoma
-fibrosarcoma, optic nerve glioma, meningioma
2. secondary:
-metastatic, multicentric extension from the CNS or nasal cavity
-SCC, lymphoma, nasal carcinoma
-poor prognosis as most are malignant
diagnosis:
1. routine screening: bloodwork, thoracic rads, LN aspirates, abdominal ultrasound
2. orbital imaging: US, CT, MRI
-guided FNA or biopsy for dx and px
therapy:
1. surgical excision: orbitotomy or exteneration
2. adjunctive therapy: RT, chemo
describe proptosis
- exophthalmos with entrapment of the eyelids behind the globe equator
- caused by trauma: HBC. dog bite, kicked by horse, restraint in predisposed brachycephalics
- exam:
-keep globe lubricated while assessing and managing systemic condition!!
-palpate for gross orbital fractures
-PLRS: positive consensual in/to other eye is positive prognostic indicator
-fluorescein stain: concurrent ulcers are common!
hyphema indicates poorer prognosis - treatment:
-surgical replacement: if reasonable expectations for preservation of comfortable, cosmetic globe +/- vision
-enucleation: if dessicated (chronic), ruptured globe, or hanging by a thread (more than 3 EOMs avulsed, ON visible)
-if in doubt: replace, can alwas remove later - favorable prognostic factors:
-brachycephalic dogs: shallow orbits require less force to proptose
-vision
-acute/short duration
-less severe
-normal globe otherwise: vision, PLR to contralateral eye (consensual in contralateral eye) - negative prognostic factors:
-non-brachycephalic dogs: more force required, other injuries more likely
-cats, horses
- more than 3 EOM avulsed
- hyphema
- globe laceration/rupture
- facial fractures - sequelae:
-corneal ulceration
-blindness: 29% dogs regain, 100% cats blind
-strabismus: lateral most common (medial rectus tear)
-KCS
-lagophthalmos and exposure keratitis
describe orbital surgery
- surgical exploration: potentially diagnostic and therapeutic
- salvage procedures for blind painful eyes
