Lecture 21 4/24/25

Question 1

What is exophthalmia?

Answer 1

globe is positioned too far forward

Question 2

What are the two types of exophthalmia?

Answer 2

-pathologic: secondary to some type of pathology
-breed related: due to shallow orbits

Question 3

What is enophthalmia?

Answer 3

globe is positioned too far back

Question 4

What is lagophthalmia?

Answer 4

inability to blink properly over the globe

Question 5

What is proptosis?

Answer 5

eyelid margin is trapped behind the equator of the globe

Question 6

What is buphthalmia?

Answer 6

globe is enlarged secondary to prolonged elevated intraocular pressure

Question 7

What is microphthalmia?

Answer 7

born with an abnormally small globe that can be visual or non-visual

Question 8

What is phthisis bulbi?

Answer 8

shrunken globe secondary to chronic intraocular pathology that is non-visual

Question 9

Which structures contribute to the anatomy of the orbit?

Answer 9

-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

Question 10

Which aspect of orbit anatomy plays a key role in orbital disease development and presentation?

Answer 10

the fact that there is just tissue (and no bone) between the floor of the orbit and the pterygopalatine fossa

Question 11

How does the facial structure of different dog breeds affect the amount of retrobulbar space?

Answer 11

-dolichocephalic breeds: lots of space
-mesocephalic: medium
-brachycephalic: little

Question 12

What are the characteristics of orbit vasculature?

Answer 12

-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

Question 13

What are the characteristics of exophthalmia?

Answer 13

-abnormal protrusion or bulging forward of eyeball
-principle clinical sign in dogs with orbital dz
-most easily seen by viewing animal from above

Question 14

What are the potential etiologies of exophthalmia?

Answer 14

-any space-occupying retrobulbar lesion
-neoplasia
-cellulitis/abscess
-inflammatory
-cyst
-vascular anomaly
-old proptosis that did not fully reduce
-breed-related or conformational

Question 15

How is exophthalmia differentiated from buphthalmia?

Answer 15

-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

Question 16

What are the primary signs of orbital disease besides exophthalmia?

Answer 16

-third eyelid protrusion
-reduced retropulsion

Question 17

What are the characteristics of reduced retropulsion?

Answer 17

-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

Question 18

What are the variable clinical signs of orbital dz?

Answer 18

-ocular deviation
-periocular pain
-pain on opening the mouth
-periocular swelling
-blindness or other neuropathies
-retinal lesions
-auscultable bruit

Question 19

What can cause enophthalmia?

Answer 19

-pain
-atrophy of muscle or fat
-neurologic
-cachexia/aging
-dehydration

Question 20

Which diagnostics are important in diagnosing orbital dz?

Answer 20

-exam; make sure to open mouth
-blood work
-imaging
-FNA or biopsy
-culture and sensitivity

Question 21

What are the characteristics of infectious orbital dz/retrobulbar cellulitis?

Answer 21

*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

Question 22

What is the presentation of infectious orbital dz?

Answer 22

-acute onset
-exophthalmia and retrobulbar swelling
-eye looks “hotter”
-painful on palpation and/or with opening mouth
-inappetence
-possibly febrile
-possible inflammatory leukogram

Question 23

What are the treatment steps for infectious orbital dz?

Answer 23

-oral antibiotics
-anti-inflammatories
-analgesics
-surgery
-topical lube for eye if exophthalmic

Question 24

Which antibiotics are best for infectious orbital dz?

Answer 24

-clavamox
-possibly metronidazole
-NOT cefovecin/convenia

Question 25

What are the sequelae of infectious orbital dz?

Answer 25

-enophthalmia due to loss of retrobulbar fat -extension into calvarium

Question 26

What are the characteristics of inflammatory orbital dz?

Answer 26

-inflammation of extraocular or pterygoid masticatory muscles -presents with bilateral exophthalmia -treated with immunosuppression

Question 27

What are the potential etiologies of inflammatory orbital dz?

Answer 27

-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

Question 28

How is inflammatory orbital dz diagnosed?

Answer 28

-clinical signs -2M myofiber antibody serology: positive with MMM, negative with EOM -biopsy: recommended for MMM, not for EOM

Question 29

What is the typical presentation of retrobulbar neoplasia?

Answer 29

-older animals -slowly progressive exophthalmia -third eyelid protrusion -not painful on opening mouth -possible ocular deviation -possible retinal indentation -oral cavity exam normal

Question 30

What are the characteristics of retrobulbar neoplasia etiology?

Answer 30

-typically malignant -often mesenchymal; fibrosarcoma or undifferentiated sarcoma -can be carcinoma, lymphoma, mast cell tumor, hemangiosarcoma, or meningioma

Question 31

How is retrobulbar neoplasia diagnosed?

Answer 31

-clinical signs and history -ultrasound -advanced imaging -skull rads possible; not helpful -FNA

Question 32

What are the characteristics of retrobulbar neoplasia diagnosis?

Answer 32

-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

Question 33

What are the general characteristics of proptosis?

Answer 33

-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

Question 34

What is the presentation of proptosis?

Answer 34

-patient presents with history of trauma -often brachycephalic -ruptured extraocular muscles and intense retrobulbar swelling that prevents reduction of eye without GA -diagnosed with examination

Question 35

What are the steps to proptosis treatment?

Answer 35

-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

Question 36

When is enucleation the best option for proptosis treatment?

Answer 36

-globe rupture -intraocular hemorrhage -avulsion of 3 or more muscles -optic nerve avulsion

Question 37

What are the indications for enucleation?

Answer 37

irreparably painful, blind, or both

Question 38

What are the characteristics of the subconjunctival enucleation technique?

Answer 38

-globe is transected out first -all glandular tissue is removed separately -best visualization of all structures during dissection -less hemorrhage

Question 39

What are the characteristics of the transpalpebral enucleation technique?

Answer 39

-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

Question 40

What are the complications for either enucleation approach?

Answer 40

-hemorrhage -cyst -infection

Question 41

What are the characteristics of exenteration?

Answer 41

-removal of globe and all surrounding tissue within orbit with transpalpebral approach -necessary for retrobulbar/peribulbar tumors