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Ophthalmology > Globe and Orbit > Flashcards

Globe and Orbit Flashcards

1
Q

a part of the adnexa, the conical boney structure that contains the eyeball and periorbital cone

A

Boney orbit

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2
Q

What does the boney orbit contain

A

1) Eyeball
2) Periorbital cone

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3
Q

supportive cone like structure that contains the eyeball, extraocular muscles, fat, vessels, and fascia that reside within the orbit

A

Periorbital cone

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4
Q

Where is the periorbital cone

A

within the orbit

structure that contains the eyeball, extraocular muscles, fat, vessels, and fascia

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5
Q

ligamentous structure that forms the lateral boundary of the boney orbit in cats and dogs

A

orbital ligament

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6
Q

abnormal protrusion of the eye from the orbit.
abnormal position but normal globe size

A

Exophthalmos

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7
Q

T/F: the globe is larger in exophthalmos, which is why it ptroudes

A

False- abnormal position but normal size

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8
Q

abnormal recession of the eye within the orbit
glboe is normal size

A

enophthalmos

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9
Q

abnormal enlargement of the eyeball
normal position
ex: only caused by glaucoma

A

Buphthalmos

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10
Q

congenitally small and malformed globe

A

micropthalmos

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11
Q

an acquired shrunken globe, most often from severe or chronic inflammation

A

Phthisis bulbi

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12
Q

anterior displacement of the globe such that the eyelids are caught behind the equator of the globe

A

Proptosis

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13
Q

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

A

strabismus

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14
Q

What is the purpose of the boney orbit

A

1) Bony fossa for protection
2) Provides foramen for vascular and neural access
3) Depth and position of orbit helps dictate visual field and depth perception

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15
Q

surgical procedure to remove all contents of periorbital cone

A

enucleation

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16
Q

what sinuses are close to the orbit

A

front and maxillary sinuses

orbital disease can cause sinus disease and vise versa

ex: sinusal diseases can impact the orbit
like tooth root abscess

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17
Q

dental disease often induces

A

orbital or periorbital disease
especially the carnassial tooth (4th maxillary premolar)

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18
Q

What tooth commonly induces orbital or periorbital disease

A

especially the carnassial tooth (4th maxillary premolar)

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19
Q

what salivary gland is close to the orbit where inflammation of this tissue will lead to displacement of the globe

A

Zygomatic salivary gland

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20
Q

What muscles are often associated/involved with orbital inflammation **

A

1) Masseter
2) Temporalis
3) Pterygoid

swelling or atrophy can influence the eye

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21
Q

How does the mandible influence orbital disease *

A

movement of the ramus of mandible compresses inflammed orbital soft tissues and can cause severe pain

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22
Q

What might be preventing a dog from eating

A

orbital disease - open the mouth and see if there is pain, this may be causing them not to eat

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23
Q

T/F: dogs have complete orbit

A

false- incomplete orbit

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24
Q

T/F: felines have complete orbit

A

false - incomplete orbit

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25
Q

T/F: horses have a complete orbit

A

true- for protection (head butting)

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26
Q

what is the advantage of incomplete orbit

A

allows greater movement of the ramus of the mandible for biting

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27
Q

what forms the lateral boundary of the orbital rim

A

orbital ligament

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28
Q

Do dogs or cats have a shorter orbital ligament

A

cats- gives their boney more protection relative to the dog

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29
Q

In brachycephalics, the orbital ligament ________

A

spans a greater portion of the orbital rim

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30
Q

What differences to the orbit do brachycephalics have

A

1) Orbital ligament spans a greater portion of the orbital rim in brachycephalic dogs
2) Orbit is much shallower, relative to dolichocephalic dogs

these structures make them susceptible to ocular disease

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31
Q

visual field is determined by

A

the position of the orbit within the skill

this is influences by your environmental niche and feeding habits

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32
Q

are brachycephalic or dolichocephalic dogs more susceptible to ocular disease

A

Brachycephalic breeds
1) Orbital ligament spans a greater portion of the orbital rim in brachycephalic dogs
2) Orbit is much shallower, relative to dolichocephalic dogs

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33
Q

Disorders of globe position

A

1) Exopthalmos
2) Strabismus
3) Enopthalmos

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34
Q

Disorders of globe size

A

1) Bupththalmos
2) Phthisis bulbi
3) Microphthalmos

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35
Q

What are the clinical signs of exophthalmos *

A

1) Third eye lid protrusion (pushing on it) **
2) facial swelling
3) Soft palate bulging
4) Pain opening mouth/anorexia
5) fever

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36
Q

What typically causes exophthalmos in older dogs

A

likely orbital neoplasia-
-often malignant
-slowly progressive
-often non-painful

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37
Q

What typically causes exophthalmos in younger dogs*

A

orbital cellulitis/abscess
-working dogs and stick chewers
-Acute onset
-often painful

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38
Q

What are the clinical signs of retrobulbar neoplasia

A

1) Exophthalmos (gradual onset)
2) Elevated 3rd eyelid
3) No pain on opening mouth
4) Globe deviation (strabismus) -> position may indicate location of mass

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39
Q

strabismus due to retrobulbar abscess is typically

A

dorso-lateral strabismus

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40
Q

where do retrobulbar masses typically occur

A

ventral and medial to the globe this pushes the eye out and lateral (dorsolateral strabismus)

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41
Q

What are common causes of exophthalmos

A

1) Orbital neoplasia (older dogs)- malignant, slowly progressive, often non-painful
2) Orbital cellulitis/asbcess (younger dogs)- acute onset and very painful
3) Masticatory muscle myositis
4) Extraocular myositis
5) Zygomatic salivary gland mucocele
6) Retrobulbar hemorrhage

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42
Q

Which is painful, which is non-painful
-Orbital neoplasia
-Orbital cellulitis/abcess

A

Orbital neoplasia: non-painful
Orbital cellulitis/abscess: painful

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43
Q

Exophthalmos is protrusion of the globe and often the _________ *

A

third eyelid

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44
Q

Masses in the orbital space will

A

change position of the glboe depending on the location

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45
Q

An older dog with exophthalmos and lateral strabismus likely has _______ *

A

A retrobulbar mass ventral and medial to the globe that pushes the eye out and laterally

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46
Q

How does masticatory muscle myositis cause exophthalmos

A

reduction of the orbital space causes the globe to be pushes out from the orbit
results in inflammatory extraocular myositis = bilateral googly eyes

then when atrophy set in, this will cause enopthalmos

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47
Q

Masticatory muscle myositis causing exophthalmos typically unilateral or bilateral

A

bilateral

48
Q

What are the clinical signs of Orbital cellulitis/abscess

A

-Rapid onset
-Elevated 3rd eyelid
-exopthalmos
-conjunctivities
-pain on opening mouth (cats)

typically younger dogs

49
Q

What typically causes periorbital inflammation / infection

A

-Retrobulbar abscess
-Salivary mucoceles
-immune mediated myositis
-tooth rooth abscess
-orbital cellulitis
-sinusitis

dx: CT/MRI or ultrasound

50
Q

How do you diagnose periorbital inflammation / infection

A

-ultrasound is best way (also CT or MRI)
-retrobulbar aspiration

51
Q

What breeds will have normal exophthalmos due to their short orbits

A

brachycephalic breeds

52
Q

Conformational Exophthalmos

A

exophthalmos that is “ normal” in brachycephalics due to their shallow orbits and straight face
bilateral
no protrusion of nictitans
typically have lateral strabismus

leads them more susceptible to disease

53
Q

buphthalmos

A

enlarged globe typically due to glaucoma
third eyelid is not protruding with the buphthalmic globe in general

54
Q

What is a major clinical sign for an eye that looks enlarged that confirms it is Buphthalmos and not exophthalmos *****

A

Buphthalmos generally does not have protrusion of the third eye lid

also Buphthalmos will have increased intraocular pressure

55
Q

How do you tell Buphthalmos from Exopthalmos **

A

1) Increased intraocular pressure
2) No protrusion of the third eyelid
3) Look from above at corneal curvature to see if there is anterior displacement of a normal sized globe (exophthalmos)
4) Look from straight ahead (horse)
5) Retropulse globe -push eye into orbit through closed eyelid - exopthalmic globe will have limited retropulsion compared to normal eye
Painful if retrobulbar abscess or inflammation

56
Q

How does retropulsing the glboe differ in dogs with exopthalmos vs buphthalmos *

A

Exopthalmos: will not have limited retropulsion compared to the normal eye

Buphthalmos: feels firmer

57
Q

Might be happening if a dog has exopthalmos and their is pain upon retropulsion of the globe **

A

retrobulbar abscess or inflammation

58
Q

How do you diagnose exophthalmos *

A

1) Look from above or straight on- compare to normal eye
2) Retropulse globe- push eye into orbit through closed eyelid
3) Nictitans protrusion: generally present with true exophthalmos

59
Q

Diagnostic approach for exophthalmos

A

-Complete general and ophthalmic examination - observe for orbital globe symmetry and pain on opening mouth
-CBC/ CHEM
+/- chest rads for tumor metastasis for neoplasia
advanced imaging (CT/MRI)
Tissue sampling (fine needle aspiration-less specific and biopsy)

60
Q

If you see peri-orbital swelling how do you get a sample for further diagnostics

A

aspirate behind the molars
differentials:
tooth root abscess
zygomatic mucocele
cellulitis
foreign body
trauma

61
Q

What are the two treatment approaches to orbital neoplasia *

A

1) Globe sparing - most often palliative
-Radiation
-Surgical exploration
-Chemotherapy

2) Glove removal (also palliative)
Enucleation: removal of the eye
Exenteration: removal of the eye and all orbital contents

62
Q

What are three consequences of being exophthalmic

A

1) dry eye
2) corneal ulceration
3) retinal detachement

63
Q

removal of the globe and secretory components: eyelids, lacrimal glands, and 3rd eye lid

A

enucleation

64
Q

removal of the globe and all orbital contents (secretory components, periorbital fat, muscles)

A

exenteration

65
Q

what is enucleation, what else is removed, aside from the globe

A

secretory components: eyelids, lacrimal glands, 3rd eyelids

66
Q

What are the 2 treatment approaches for orbital cellulitis/abscess *

A

1) Medical (if eating)
NSAID or Steroids AND broadspectrum antbitoics (ie Clavamox)

2) Surgical exploration and/or drainage

67
Q

What are the 3 causes on enopthalmos

A

1) Orbital volume imbalances: ex: atrophy of muscles

2) Active globe retractions (skeletal muscle- retractor bulbi CN VI) -could be due to corneal pain

3) Passive globe retraction (smooth muscles of periorbital cone- sympathetic- Horners)

68
Q

What are main causes of orbital volume imbalances leading to enophthalmos

A

1) Dehydration
2) Emaciation or cachexia
3) Myopathies

69
Q

What might cause enophthalmos due to active globe retraction (Retractor bulbi)

A

ocular pain (ie corneal pain)

70
Q

What might cause enopthalmos due to passive retraction (periorbital cone muscles)

A

Horner’s syndrome- smooth muscles of periorbital cone is under sympathetic innervation

71
Q

enophthalmos from ocular pain is likely due to

A

corneal ulcers

72
Q

What are the clinical signs of corneal ulcers

A

1) Enophthalmos (retraction of the globe from pain)
2) Blepharospasm (Closing of eyelids)
3) Raised 3rd eyelid
4) Miosis -> reflex uveitis

73
Q

Why do you see miosis with corneal ulceration

A

from reflex uveitis

74
Q

a condition where the pupil of the eye is constricted or abnormally small

A

miosis

75
Q

the dilation of the pupil, usually having a non-physiological cause, or sometimes a physiological pupillary response

A

mydriasis

76
Q

What happens if the muscles of mastication are atrophied (ie. masticatory muscle myositis- inflammation or steroid use)

A

orbital volume imbalances -> causes enophthalmos

77
Q

What medication can lead to loss of surrounding musculature and enophthalmos

A

chronic steroid use
“pred head”

78
Q

What are possible complications of enophthalmos

A

1) Increased space for third eyelid
2) Third eyelids covers globe- vision impairment
3) Entropion - from lack of globes supporting

79
Q

What are common clinical signs of enophthalmos due to loss of musculature

A

1) facial muscular loss (unilateral or bilateral)
2) third eyelid protrusion
3) entropion

80
Q

What are the 4 clinical signs of Horner’s syndrome **

A

1) Ptosis
2) Enophthalmos
3) Third eyelid elevation 4) Miosis

81
Q

Ptosis

A

a condition that causes the upper eyelid to droop or fall, which can affect one or both eyes

82
Q

sympathetic denervation to the eye and ocular adnexa leads to

A

Horner’s Syndrome
1) Ptosis- dropping of upper eyelid
2) Enophthalmos - sunken back eye
3) Third eyelid elevation 4) Miosis- constricted

83
Q

How do you distinguish Horner’s from a painful eye?

A

Proparacaine - numbs the eye. if its reflex to corneal ulcer then it will resolve within 90 seconds

Horners: 1 drop of sympathomimetic (Phenylephrine) and then the 3rd eyelid will come up and eye will dilate

84
Q

With Horner’s Syndrome, upon dropping phenyelphrine in the eye, will you see results sooner in pre or post-ganglionic lesions?

A

Post-ganglionic lesions you will see retraction of 3rd eyelid and dilation sooner <20minutes

40-60 minutes: Preganglionic lesion

85
Q

With pre-ganglionic lesions of Horner’s Disease you will see
Retraction of third eye lid and dilation of the eye within

A

40-60 minutes

way longer than post ganglionic lesions

86
Q

With post-ganglionic lesions of Horner’s Disease you will see retraction of the 3rd eyelid and dilation of the eye within

A

<20minutes

way shorter than pre-ganglionic lesions

87
Q

In Horner’s Disease, dropping phenylephrine will result in

A

1) Dilation of the eye (mydriasis)
2) Retraction of third eyelid

Post-ganglionic lesion: <20min
Pre-ganglionic lesions: 40-60min

88
Q

a congenitally small and malformed globe

A

microphthalmos

89
Q

an acquired shrunken globe, most often from severe or chronic inflammation and causes lack of aqueous humor production
leading to decrease in size of the globe

often not visual

A

Phthisis bulbi

90
Q

What are the 2 disorders that lead to a smaller globe size

A

1) Microphthalmos- congenital and malformed
2) Phtisis bulbi- acquired shrinkage due to chornic inflammation and lack or aqueous humor production

91
Q

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

A

strabismis

92
Q

What are causes of congenital stabismus

A

1) Normal variation- brachycephalic dogs with divergent stabismus due to abnormal volume

2) Siamese cats- convergent strabismus (abnormal visual processing)

3) Hydrocephalus- ventrolateral divergent strabismus (abnormal orbital volume)

93
Q

What breed typically gets convergent strabismus

A

Siamese cats
leads to abnormal visual processing

94
Q

What kind of strabismus does hydrocephalus lead to

A

Ventrolateral divergent strabismus

due to abnormal orbital volume

95
Q

Siamese cats get _________ strabismus while Brachycephalic dogs get _______ strabismus

A

Siamese: convergent strabismus

Brachycephalics: divergent strabismus

96
Q

Brachycephalic breeds have a “normal variation” that leads to _________ strabismus from ___________

A

divergent strabismus from abnormal orbital volume

97
Q

What are acquired causes of strabismus

A

1) Mechanical or nervous dysfunction of any rectus muscle
CN III: dorsal, ventral, medial rectus muscles and ventral oblique
CN IV: Dorsal oblique
CN VI: Retractor bulbi and lateral lectus

2) Imbalances of orbital volume -> third eyelid neoplasia

98
Q

What strabismus would you see from dysfunction of CN VI

A

Medial strabismus

CN VI works to innervate retractor bulbi and lateral rectus so dysfunction would cause the eye to move medially

99
Q

What strabismus would you see from medial rectus damage follow proptosis

A

Lateral strabismus

100
Q

Why is acquired lateral strabismus the most common

A

1) Masses tend to grow ventromedial which causes a dorsolateral strabismus

2) Medial rectus is the shortest muscles which damage to it commonly causes a lateral strabismus

101
Q

anterior displacement of the globe such that the eyelids are caught behind the equator of the globe *

A

Proptosis

102
Q

Proptosis is very common in

A

brachycephalic breeds
-often involves minimal trauma

103
Q

At what distinction do you consider an anterior displaced eye “Proptosis” *

A

if the globe is pushes such that the eyelids are caught behind the equator of the globe
-Proptosis would want to fix

104
Q

What are two considerations when considering proptosis prognosis *

A

1) Vision?
Poor prognosis as >75% are blinded (optic nerve trauma)
2) Globe retention?- variable prognosis
indicators:
-Rupture of eye
-Hyphema
-Orbital bone fractures
-Owner compliance

105
Q

In dogs with proptosis, what is the prognosis of gaining vision

A

75% are blinded (optic nerve trauma)

106
Q

Dogs have ______ extraocular muscles torn with proptosis have better prognosis of globe retentions

A

<3 extraocular muscles torn

107
Q

With proptosis, what tells you there is a better prognosis of globe retention

A

1) Brachycephalics
2) <3 extra-ocular muscles torn
3) Positive direct and consensual PLRs

108
Q

With proptosis, what tell you there is a poor prognosis

A

1) Cats
2) Dolichocephalic dogs
3) >3 extraocular muscles torn
4) Ruptured eye
5) Hyphema
6) Orbital fractures

109
Q

How do you treat proptosis

A

1) E-collar and lubricate eye
2) Pain management, sedation, or anesthesia- vagal response can cause cardiac arrest/death
3) Clip and clean eyelids
4) Place stay sturues
5) Apply counter pressure to the eye with a clean, flat, blunt surface
6) Place temporary partial tarsoorhaphy - at the meibomian glands
7) Insititute appropiate medical therapy
8) Do not remove tarsohaphy until orbital swelling is completely resolves (at least 2-3 weeks)

110
Q

a surgical procedure in which the eyelids are closed
can be temporary or permanent, partial or complete

A

Tarsorrhaphy

111
Q

What should you do for proptosis after-care

A

-Ecollar- hard plastic
-Topical antibiotic
-+/- topical atropine- if uveitis or ulceration is present
-oral antibiotic
-oral NSAID or steroid
-additional analgesia
-manage complication if arise

112
Q

What are complications of Proptosis tx

A

1) Corneal ulceration - from misplaced sutures
2) Loosening sutures
3) Strabimus- medial rectus is shortest and most easily torn leading to lateral strabismus
4) Keratoconjunctivitis sicca
5) Blindness
6) Repeated proptosis
7) Need for enucleation

113
Q

What is the shortest rectus muscle and most prone to being torn

A

Medial rectus

-commonly to get lateral strabismus from this

114
Q

you should never apply contact solution to the eye

A

True

115
Q

what is the purpose of the mucin components of tear film

A

bind serous layer to the cornea

Ophthalmology (7 decks)

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