Lecture 21 4/24/25 Flashcards
What is exophthalmia?
globe is positioned too far forward
What are the two types of exophthalmia?
-pathologic: secondary to some type of pathology
-breed related: due to shallow orbits
What is enophthalmia?
globe is positioned too far back
What is lagophthalmia?
inability to blink properly over the globe
What is proptosis?
eyelid margin is trapped behind the equator of the globe
What is buphthalmia?
globe is enlarged secondary to prolonged elevated intraocular pressure
What is microphthalmia?
born with an abnormally small globe that can be visual or non-visual
What is phthisis bulbi?
shrunken globe secondary to chronic intraocular pathology that is non-visual
Which structures contribute to the anatomy of the orbit?
-globe
-optic nerve
-extraocular muscles
-branches from cranial nerves 3, 4, 5, 6, and 7
-peripheral nerves
-fat
-vasculature
-connective tissue
-bone
-lacrimal and third eyelid gland
-zygomatic salivary gland
Which aspect of orbit anatomy plays a key role in orbital disease development and presentation?
the fact that there is just tissue (and no bone) between the floor of the orbit and the pterygopalatine fossa
How does the facial structure of different dog breeds affect the amount of retrobulbar space?
-dolichocephalic breeds: lots of space
-mesocephalic: medium
-brachycephalic: little
What are the characteristics of orbit vasculature?
-maxillary artery lives at the “floor” of the orbit
-several small arteries are present when transecting globe for enucleation
-want to avoid angularis oculi vein in enucleation and medial eyelid surgeries
What are the characteristics of exophthalmia?
-abnormal protrusion or bulging forward of eyeball
-principle clinical sign in dogs with orbital dz
-most easily seen by viewing animal from above
What are the potential etiologies of exophthalmia?
-any space-occupying retrobulbar lesion
-neoplasia
-cellulitis/abscess
-inflammatory
-cyst
-vascular anomaly
-old proptosis that did not fully reduce
-breed-related or conformational
How is exophthalmia differentiated from buphthalmia?
-buphthalmia will present with elevated IOP unless eye is being treated with glaucoma meds or is burnt out
-exophthalmia typically does not present with elevated IOP or will have a mild IOP elevation
What are the primary signs of orbital disease besides exophthalmia?
-third eyelid protrusion
-reduced retropulsion
What are the characteristics of reduced retropulsion?
-globe does not push back into orbit normally
-seen with exophthalmia
-buphthalmic dogs will have a firm globe that retropulses normally
-brachycephalics will have a variation on normal reduced retropulsion due to shallow orbits
What are the variable clinical signs of orbital dz?
-ocular deviation
-periocular pain
-pain on opening the mouth
-periocular swelling
-blindness or other neuropathies
-retinal lesions
-auscultable bruit
What can cause enophthalmia?
-pain
-atrophy of muscle or fat
-neurologic
-cachexia/aging
-dehydration
Which diagnostics are important in diagnosing orbital dz?
-exam; make sure to open mouth
-blood work
-imaging
-FNA or biopsy
-culture and sensitivity
What are the characteristics of infectious orbital dz/retrobulbar cellulitis?
*common in dogs and cats
*bacterial and fungal dz common
-cellulitis or abscess
-infection stemming from:
-hematogenous spread
-oral cavity
-periocular penetrating injury
-extension from surrounding tissue
What is the presentation of infectious orbital dz?
-acute onset
-exophthalmia and retrobulbar swelling
-eye looks “hotter”
-painful on palpation and/or with opening mouth
-inappetence
-possibly febrile
-possible inflammatory leukogram
What are the treatment steps for infectious orbital dz?
-oral antibiotics
-anti-inflammatories
-analgesics
-surgery
-topical lube for eye if exophthalmic
Which antibiotics are best for infectious orbital dz?
-clavamox
-possibly metronidazole
-NOT cefovecin/convenia
What are the sequelae of infectious orbital dz?
-enophthalmia due to loss of retrobulbar fat
-extension into calvarium
What are the characteristics of inflammatory orbital dz?
-inflammation of extraocular or pterygoid masticatory muscles
-presents with bilateral exophthalmia
-treated with immunosuppression
What are the potential etiologies of inflammatory orbital dz?
-extraocular muscle myositis: non-painful, immune-mediated disease targeting only the extraocular muscles
-masticatory muscle myositis: immune-mediated disease targeting the masseter, temporalis, and pterygoid masticatory muscles
How is inflammatory orbital dz diagnosed?
-clinical signs
-2M myofiber antibody serology: positive with MMM, negative with EOM
-biopsy: recommended for MMM, not for EOM
What is the typical presentation of retrobulbar neoplasia?
-older animals
-slowly progressive exophthalmia
-third eyelid protrusion
-not painful on opening mouth
-possible ocular deviation
-possible retinal indentation
-oral cavity exam normal
What are the characteristics of retrobulbar neoplasia etiology?
-typically malignant
-often mesenchymal; fibrosarcoma or undifferentiated sarcoma
-can be carcinoma, lymphoma, mast cell tumor, hemangiosarcoma, or meningioma
How is retrobulbar neoplasia diagnosed?
-clinical signs and history
-ultrasound
-advanced imaging
-skull rads possible; not helpful
-FNA
What are the characteristics of retrobulbar neoplasia diagnosis?
-by the time of diagnosis most cases are too advanced to successfully treat
-treatment that is pursued is palliative, not curative
-can do orbitotomy or exenteration followed by radiation
What are the general characteristics of proptosis?
-emergency that must be treated urgently
-want to check patient for other head and neck trauma
-do a neuro exam
-clip to check for wounds
-take caution when restraining brachycephalics; can cause iatrogenic proptosis
What is the presentation of proptosis?
-patient presents with history of trauma
-often brachycephalic
-history of trauma
-ruptured extraocular muscles and intense retrobulbar swelling that prevents reduction of eye without GA
-diagnosed with examination
What are the steps to proptosis treatment?
-clean thoroughly
-reduce and place temporary tarsorrhaphy
-leave temp. tarsorrhaphy for 2 to 3 weeks
-use topical antibiotics and lubricants through medial canthal opening
-use topical atropine for hyperemia or uveitis
-systemic antibiotics for 1 week
When is enucleation the best option for proptosis treatment?
-globe rupture
-intraocular hemorrhage
-avulsion of 3 or more muscles
-optic nerve avulsion
What are the indications for enucleation?
irreparably painful, blind, or both
What are the characteristics of the subconjunctival enucleation technique?
-globe is transected out first
-all glandular tissue is removed separately
-best visualization of all structures during dissection
-less hemorrhage
What are the characteristics of the transpalpebral enucleation technique?
-eyelids are sutured together first
-tissue is removed en bloc, all attached to one another
-required technique for corneal infections and neoplasia of eyelid and/or conjunctiva
-can have more tissue trauma and/or remove more tissue than necessary
What are the complications for either enucleation approach?
-hemorrhage
-cyst
-infection
What are the characteristics of exenteration?
-removal of globe and all surrounding tissue within orbit with transpalpebral approach
-necessary for retrobulbar/peribulbar tumors
