Orbit

Question 1

boney orbit

Answer 1

part of the adnexa

conical boney structure that contains the eyeball and periorbital cone

Question 2

which sinuses can cause orbital disease and vice versa

Answer 2

frontal and maxillary

Question 3

T/F dental disease often induces orbital or periorbital disease

Answer 3

True

especially the carnassial tooth (PM4)

Question 4

inflammation of the _________ will lead to displacement of the globe

Answer 4

zygomatic salivary gland

Question 5

which muscles are often associated/involved with orbital inflammation

Answer 5

muscles of mastication

masseter, temporalis, pterygoid

Question 7

why should mouth gags not be used in cats

Answer 7

distrupt carotid/maxillary arterial supply to the orbit

can result in temporary or perminant blindness

Question 8

cats and dogs have open/closed orbits

Answer 8

open

• orbital ligament forms the lateral boundry of orbital rim*
• note: relatively much shorter in cats giving them more boney protection*

Question 9

differences in orbit between brachycephalic and dolicephalic breeds

Answer 9

brachycephalic - orbital ligament spans a greater portion of the orbital limb and the orbit is much shallower

Question 10

which species have closed orbits

Answer 10

ruminants and horses

Question 11

disorders of globe position

Answer 11

exophthalmos

endophthalmos

strabismus

Question 12

disorders of globe size

Answer 12

buphthalmos

phthisis bulbi

microphthmalmos

Question 13

clinical signs commonly associated with exopthalmos

Answer 13

third eyelid protrusion

facial swelling

soft palate bulging

pain opening mouth

fever

Question 14

common causes of exopthalmos

Answer 14

orbital volume imbalance

neoplasia

cellulitis/abscess

Question 15

T/F brachycephalic breeds will have “normal” exophthalmos

Answer 15

True

this is due to their shallow orbits

Question 16

strabismus

Answer 16

deviation of one or both eyes so that both eyes are not directed at the same object

Question 17

buphthalmos

Answer 17

enlargement of the globe due to glaucoma

Question 18

A labrador presents with exophthalmos OD with pain elicited by movement of the manidble. Tonometry reveals and IOP of 15mmHg. What is your number 1 differential

Answer 18

cellulitis/abscess

orbital neoplasms are typically non-painful, gluacoma is present with IOP >25mmHg

Question 19

diagnostic approach to exophthalmos

Answer 19

complete general and ophthalmic exam

CBC, CHEM

+/- chest rads

advanced imaging (CT, MRI)

tissue sampling (FNA, Biopsy)

Question 20

2 treatment approches to orbital neoplasia

Answer 20

globe sparing - radiation, chemotherapy, surgical exploration

globe removal - enucleation, exenteration (removal of eye and all orbital contents)

Question 21

2 treatment approaches to orbital cellulitis/abscess

Answer 21

medical - NSAIDs/steroids and Antibiotics (Clavamox-broad spectrum)

surgical exploration and/or drainage

Question 22

enophthalmos

Answer 22

abnormal recession or eye within the orbit

Question 23

common clinical signs of enophthalmos

Answer 23

facial muscular loss (unilateral or bilateral)

3rd eyelid protrusion

entropion (eyelid folds inward)

Question 24

common mechanisms od enopthalmos

Answer 24

orbital volume imbalances

active globe retraction - skeletal muscle (retractor bulbi)

passive glboe retraction - smooth muscles of periorbital cone

Question 25

common causes of enopthalmos

Answer 25

dehydration

emaciation/cachexia

myopathies

spece occupying lesions anterior to globe

ocular pain

horner’s syndrome

Question 26

horner’s syndrome

Answer 26

sympathetic dennervation to the eye and ocular adnexa

Question 27

2 disorders of globe size that can be confused with enophthalmos

Answer 27

micropthalmos - congenitally small and malformed globe

phthisis bulbi - aquired shrunken globe (often from severe/chronic inflammation)

Question 28

causes of strabismus

Answer 28

congenital - “normal variation,” siamese cats, hydrocephalus

aquired - mechanical or nervous dysfunction of rectus muscles, imbalance of orbital volume

Question 29

proptosis

Answer 29

anterior displacement of globe such that the eyelids are caught behind the equator of the globe (can’t blink)

Question 30

prognositic indicators for proptosis

Answer 30

vision - poor (75% blinded)

globe retention - variable (poor - rupture, hyphema, orbital bone fractures, poor owner compliance)