1: the orbit - pearce Flashcards Preview

IP 11 Ophthalmology > 1: the orbit - pearce > Flashcards

Flashcards in 1: the orbit - pearce Deck (120):
1

when referring to location w/in the eye, what is the appropriate way to say dorsal?
ventral?
lateral?
medial?

dorsal = superior
ventral = inferior
lateral = temporal
medial = nasal

2

how many tunics are in the eye?

3

3

what are the 3 tunics of the eye?

fibrous tunic
vascular tunic
neural tunic

4

what makes up the fibrous tunic?

cornea
sclera

5

what makes up the vascular tunic?

uveal tract => iris, ciliary body, choroid

6

what is the function of the zonules in the eye?

to attach the ciliary body to the lens

7

what and where is the choriod?

vascular layer loc behind the retina

8

what is the iris?

color portion of eye

9

what makes up the neural tunic?

retina

10

what is the retina? what does it look like?

thin and microscopic visibility

neural tissue - the most advanced and complex structure in the eye

11

what makes up the internal optical media?

aqueous humor
lens
vitreous humor

12

where is the aqueous humor loc? what does it contain?

loc in the front chamber of the eye, the anterior chamber - anterior to the iris

has aqueous humor

13

where is the posterior chamber loc? what does it contain?

loc btwn iris and lens

has aqueous humor

14

what is the posterior segment? what does it contain?

contains vitreous humor

15

what is primary goal of ophthalmology in terms of patient care? and if this is not achievable, what is the next goal?

vision

comfort

16

what are main components of ophthalmology?

- signalment
- hx: chronology, medications
- neurophthalmic exam
- MDB
- ophthalmic exam

17

what do you need to conduct an ophthalmic exam?

- bright, focal light source
- darn environment
- magnification

18

what are 2 methods to conduct a retinal exam?

- indirect ophthalmoscopy
- direct ophthalmoscope

19

how to assess vision in an animal?

- vision-directed behavior
- tracking
- menace response

20

def the orbit:

a conical cavity containing the eye and its supporting structures

includes bony orbit and soft tissue

21

what are the 2 type of bony orbits?

"closed" or "complete"
"open" or "incomplete"

22

which animals have an open orbit? closed orbit?

why?

herbivores have closed orbit - orbit completely encased in bone so the mobility of the mandible is limited - jaw cannot open as much

carnivores have open orbit - part of the orbit is not encased in bone - allows much greater mobility of the mandible so the jaw can be opened wider

23

what is the orbital lig?

present in carnivores, over the area of the orbit that is not encased in bone, to provide some protection to the orbit in that area, while still allowing a higher range of motion for the jaw

24

what is the orbital cone, what structures make it up and what structures define it?

essentially, it is the "stuff" around the eye

- CT
- extra ocular Mm
- Nn
- blood vessels
- fat
- smooth M
- endorbita/periorbita

defined by the endorbita and extra ocular Mm

25

what is the endorbita/periorbita?

- fibrous CT loc next to the bone of the orbital wall
- encircles extra ocular Mm
- boundra btwn intra-conal and extra-conal spaces

26

what is the function of the extra-ocular Mm?

to move the eye

27

what are the extra-ocular Mm and how does each move the eye?

superior oblique, inferior oblique - move eye rotationally
retractor bulbi - insertion M; retro pulses the eye / pulls the eye into socket
lateral, medial, ventral and dorsal rectus Mm - move eye side to side or up and down, respectively

28

what muscles are extra-conal?

temporalis M, pterygoid M, masseter M

29

what soft tissues are extra-conal?

muscles, blood vessels and Nn, fat and CT, glands, paranasal sinuses, nasal cavity, oral cavity, roots of teeth, Cr cavity / fossa

30

what glands are loc extra-conal?

lacrimal
zygomatic salivary

31

t/f

tooth root abscesses do not affect the eye.

why or why not?

false

tooth root abscesses can affect the eye - swelling in the oral cavity/gingiva can push out the globe and affect vision - it is loc near the eye and space is very small

32

what is exophthalmos?

globe loc too far rostral - is being pushed out of the orbit/socket

33

what is enophthalmos?

globe loc too far cd

34

what is proptosis?

equator of globe anterior to palpebral fissure

essentially, severe exopphthalmos where globe is coming out of the socket/orbit

35

what is the palpebral fissure?

the opening of the eyelids

36

what is the MDB for ophthalmology exam?

Schirmer tear test
Fluorescein stain
Tonometry

37

how to examine for orbital dz?

- look from above
- retropulsion
- neurophthalmic exam
- MDB
- ophthalmic exam - anterior segment and fundus
- oral exam

38

what is retropulsion? what is a normal retropulsion of the globe?

close patient eyes and push on eyeball - should be able to push it in a little bit

should NOT be resistance or pain - if there is, something is wrong

39

if the eye appears large and/or swollen, what are 2 differentials?

exophthalmos and bupthalmos

40

what is bupthalmos?

eye is too large

41

how to distinguish exophthalmos from bupthalmos?

look at alignment and diameter of cornea

exo: cornea is NOT aligned but has a normal diameter
bup: cornea is aligned but has a larger diameter than it should

42

what are c/s of orbital dz?

- inc or dec scleral show
- dec retropulsion
- elevation of Nictitans
- difficulty of discomfort opening mouth

43

why is the Nictaitans, or 3rd eyelid, important to evaluate in orbital dz?

functions as a sentinal for orbital dz

it should be down but will elevate in orbital dz

44

why might difficulty opening the mouth indicate orbital dz?

the motion of the ramus of the mandible will push on the orbit and cause pain or discomfort in the globe in some orbital dz processes

45

t/f

pain when opening the mouth is a positive prognostic indicator in terms of orbital dz

true

46

what are basic diagnostics carried out during orbital dz exam?

PE - look for systemic inflammation or systemic metastatic dz
CBC, chem
skull x rays
fine needle aspirates
specialty procedures

47

what specialty procedures might be performed in an orbital dz exam?

- orbital u/s
- angiography
- advanced imaging (CT/MRI)

48

what are 2 forms of enophthahlmos?
what is a good way to distinguish btwn the two forms?

congenital
acquired

get a good history

49

what is microphthalmos

globe that is too small - congenital or acquired

presents as enophthalmos

50

what are 2 causes of congenital enophthalmos?

- microphthalmos and anophthalmos

51

what is anophthalmos?

how common is this condition?

a form of congenital enophthalmos in which there is no eye

VERY RARE

52

what is microphthalmos?

when is it most common to occur?

- congenitally small globe

- multiple ocular defects common

- merle or white coat/color diluted animals primarily [double dapple breeding of 2 merles]

53

what is the prognosis of congenital enophthalmos?

vision: poor prognosis
comfort: fair to guarded

54

what are 2 forms of acquired enophthalmos?

- phthisis bulbi: acquired dec globe size

- normal globe size with loss of orbital tissue volume

55

under what circumstances might phthisis bulbi occur?

end stage glaucoma, trauma, uveitis

56

under what circumstances might loss of orbital tissue volume occur?

bilateral: dehydration, emaciation/weight loss

unilateral: muscle or tissue atrophy => myositis, surgery, radiation

57

what is acquired enophthalmos?

a condition which causes the retraction of the globe into the orbit, when the animal was born normal

58

what are some common concurrent conditions typically seen with exophthalmos?

- lagophthalmos: inability to completely open / close eyelids

- strabismus: deviation of visual axis

59

what are some c/s assoc w exophthalmos?

- conjunctival hyperemia or chemosis
- nictitans elevation
- pain upon retropulsion or opening mouth
- keratitis

60

if an exophthalmic dog is not painful when opening the mouth, what is a differential?

tumor

61

what is the cause of exophthalmos?

space occupation

mass effect [inside or outside of cone] pushing the globe in one direction or another

62

what might cause space occupation, leading the exophthalmos?

what is more common?

cells: hyperplasia, inflammatory, neoplasia

fluid: blood, serum/cystic, lipid

air


MC cells - fluid is more of a 'zebra'

63

possible etiologies of exophthalmos inflammatory dzz?

- orbital abscess
- orbital cellulitis
- myositis: masticatory, extra ocular

64

c/s of orbital cellulitis or abscess?

- unilateral usually
- Nictitans elevation
- pain opening mouth
- fever
- inappetance
- inflammatory leukogram

65

possible etiologies of cellulitis / abscess?

tooth abscess
sinus infection
hematogenous spread
penetrating injury

66

what Dx is necessary to distinguish btwn cellulitis and abscess?

if the client does not want do to this exam, what can be done next?

orbital u/s

- alternative: can give pain control and abx - cellulitis will improve w abx but abscess will not [abscess needs to be drained surgically]
- this is less desirable b/c patient is very painful so waiting it out means more discomfort for animal

67

what is the difference btwn cellulitis and abscess?

cellulitis: solid cells
abscess: pocket of puss

68

therapy for cellulitis /abscess?

systemic abx
drainage if abscess
soft food
corneal lubrication

69

what is presentation of acute masticatory muscle myositis?

- facial muscle inflammation
- bilateral exophthalmos
- nictitans elevation
- pain on jaw movement
- pyrexia

70

what muscles are inflamed in case of masticatory muscle myositis?

pterygoid
temporalis
masseter

71

are masticatory mm intra or extra conal? what is result when they are inflammed?

they are extra conal
they push the globe out when they are inflamed

72

what is presentation of chronic masticatory muscle myositis?

enophthalmos
atrophy / fibrosis of muscles

73

what test is diagnostic for masticatory muscle myositis?

2M aby serum test: positive is diagnostic

74

what changes might be observed on CBC/chem panel for masticatory muscle myositis?

- peripheral eosinophilia maybe
- elevated CK

75

masticatory muscle myositis treatment - acute and chronic cases?

acute: systemic immunosuppression until CK is normal and jaw is moveable

chronic: conservative management of eophthalmos

supportive care maybe b/c hard to eat when painful jaw

76

what is the presentation of extra ocular muscle myositis?

bilateral exophthalmos, bug eyed appearance with lots of scleral show

"deer in headlights" or stressed look

fixed gaze

No nictitans protrusion

77

is extra ocular M myositis painful?

NO

78

what dog breed is extra ocular muscle myositis common in?

golden retreivers

79

what is etiology if extra ocular muscle myotisit?

auto immune myositis

80

where are extra ocular muscles located?

within the cone

81

dx extra ocular muscle myositis?

clin presentation is big b/c very distinct appearance

options but not necessary usually:
imaging
biopsy

82

tx extra ocular muscle myositis?

immunosuppression

83

prognosis of extra ocular muscle myositis?

recurrences common

secondary problems if chronic cases, but NOT common: cases: enophthalmos, strabismus / fibrosis

84

what is the origin of primary orbital neoplasia?

secondary?

primary: the orbit

secondary: metastasis TO the orbit from elsewhere in body

85

t/f

orbital neoplasia is usually benign

false

usually malignant, 80-90% malignacy rate

86

what is the typical presentation for orbital neoplasia?

- gradual onset
- exophthalmos
- nictitans elevation
- lack of retropulsion
- absence of pain opening mouth

87

dx of orbital neoplasia?

- CBC, chem, U/a
- ocular u/s
- CT/MRI
- cytology: mass and associated lnn
- abdominal and thoracic x rays: metastasis check
- biopsy: CT or u/s guided or Sx

88

therapy for orbital neoplasia?

dep on tumor type:

sx
chemo
radiation

89

what is prognosis of orbital neoplasia?

guarded to poor
80-95% malignancy

90

what is traumatic proptosis?

the equator of the globe lies anterior to the palpebral fissure, due to pressure from trauma

can be slightly proptosed to extremely proptosed

91

common causes of traumatic proptosis?

- bite wounds: BDLD attach
- blunt trauma: HBC, kicked by horse
- heavy restraint in some brachycephalic dogs [iatrogenic]

92

in what type of dog is traumatic proptosis MC?

brachycephalic: the more brachycephalic a dog is, the less pressure that is required to cause this condition

RARE in cats and mesencephalic / dolicocephalic dogs

93

in case of proptosis, what is the first thing you should do?

stay calm

94

what can you tell the owner to do immediately to help their pet that has proptosis?

keep eye moist in transport - corn or olive oil, eye drops, KY jelly, artificial tears, etc

95

dx proptosis?

- thorough PE - do NOT miss pneumothorax or something severe and anesthetize dog
- neuro exam
- ophthalmic exam: orbital fractures, direct/consensual PLR, ocular motility, fluorescein stain, intra ocular exam

96

postitive prognostic indicators of proptosis

- pos consensual PLR
- voluntary movement of the globe [some extra ocular M attachment remains]

97

t/f

pupil size is a reliable indicator of positive prognosis of proptosis

false - pupil size is NOT a reliable indicator

a miotic pupil indicates intact
parasympathetic innervation

98

what are negative prognostic indicators of a proptosis?

- transected nerve
- chronic proptosis (over 48 hrs)
- hyphema
- corneo-sclera laceration
- rupture > 3 extra ocular muscles
- dolicocephalic or cat
- complete bony orbit

99

what muscles often tear during proptosis?

what might occur as a result?

medial

strabismus

100

t/f

if a proptosed globe of a cat is able to be put back in, the cat will likely have normal vision

false - cat will definitely not have normal vision return

101

what might cause hyphema when a proptosis has occurred?

scleral rupture
severe uveal trauma

102

what is the tx for proptosis?

- Sx: replace (pos prognostic indicators) or enucleate (negative prognostic indicators)

stabilize patient, keep cornea lubricated

103

t/f
if there are positive prognostic indicators to suggest a surgical replacement of the globe might resolve the proptosis successfully, it is a good idea to try it anyways - if it fails, you can always remove the globe later

true

104

during Sx replacement of proptosis what kinds of sutures are used?

when placing them, what orientation do you want the eyelids to fall into?

horizontal matterss sutures

want to exit at the lid margins so the lid margins DO NOT evert

pull the lid over the globe rather than pushing the globe down

105

what is the highest "ott" suture that should be used in optical surgery?

4-0

106

medical tx for proptosis?

- systemic abx
- systemic anti inflammatory: NSAID and steroid
- topical triple abx: ointment, QID
- e collar
- tarsorrhaphy 2-3 weeks

- lots of lubrication

107

what complications might arise during a proptosis replacement?

- lagophthalmmos
- KCS
- strabismus [very common b/c hard to reattach Mm]
- blindness
- phthisus bulbi -> uveitis

108

what is lagophthalmos?

inability to blink

109

what types of enucleation are there?

- subconjunctival
- transpalpebral

110

how does subconjunctival enucleation work?

benefit to this method?

- remove "through" the conjunctiva
- remember to remove the Nictitans and residual conjunctiva
- cleaner sample for histopath

111

how does transpalpebral enucleation work?

when should this be used over subconjunctival enucleation?

- remove "through" the eyelids

- infected eyes
- intraocular neoplasia

112

what is enucleation?

removal of the globe

113

what is exenteration?

removal of the entire orbital contents, muscle and contents - down to the bone

114

what is evisceration?

removal of the intra ocular contents - leaving the fibrous tunic [cornea and sclera] behind

115

what kind of block is used to perform enucleation?

retro bulbar block - local anesthetic

116

t/f

it is always necessary to ligate the optic N in animals

false - humans but not animals

117

t/f

the best method to remove the globe during enucleation is to twist and pull the globe straight out of the orbit

false

remove in physiologic manner - rotate the globe - but DO NOT twist and pull - you can avulse the optic chiasm and cause blindness in the other eye

118

although the risk exists in both species, is it more likely to cause contralateral blindness in an enucleation procedure in a dog or a cat? why?

cats - bc they have a very short distance btwn the globe and chiasm

119

what is an advantage of the retro bulbar block to perform enucleation?

it reduces hemorrhage b/c less epinephrine is present, due to the lidocaine
also, dec amt general anesthesia needed

120

t/f

there is a high risk of an animal bleeding out from the blood vessles in its eye if they are not properly ligated during enucleation procedures.

false

this is the case in humans but not in animals - just cut it