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IP 11 Ophthalmology > lab: MDB - pearce > Flashcards

lab: MDB - pearce Flashcards

1
Q

overall importance of ophthalmic exams?

A
  • dzz of ocular support unit affect the eye, the organ that you can look inside of on an exam
  • vessels and Nn are visible in the eye
  • the anterior chamber is a direct look at “an interstitial space”
  • eye shows corroborative evidence of sys dz
  • ocular path can help narrow the differential dx and help prioritize dx testing
  • vision is important to dogs and their owners
  • if you have a land shark, lids are safer than lips :)
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2
Q

general approach to exam of the eye:

A
  • front to back

- consider relationships btwn anatomy of the tunics / layers and dzz

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3
Q

what are the 3 tunics of the eye?

A
  • fibrous tunic
  • vascular tunic
  • neural tunic
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4
Q

what comprises the fibrous tunic?

A

cornea and sclera

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5
Q

what comprises the vascular tunic

A

the uveal tract

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6
Q

what comprises the uveal tract?

A

iris
ciliary body
choriod

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7
Q

what makes up the neural tunic?

A

retina

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8
Q

what makes up the internal optical media?

A

aqueous humor
lens
vitreous humor

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9
Q

what are the goals of ophthalmology treatment / patient care?

A

vision

comfort

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10
Q

overall diagnostic approach to the eye?

A
  • ID problems
  • minimum ophthalmic database
  • clin dx
  • ddx
  • diagnostic plan
  • Tx
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11
Q

what are the aspects of the minimum ophthalmic database?

A
  • neurophthalmic exam
  • schirmer tear test
  • tonometry
  • fluorescein stain
  • complete ophthalmic exam
  • additional diagnostics
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12
Q

important questions to ask during history regarding what signs made the owner think the dog had an eye problem?

A

how does dog see with:

  • lighting
  • different environments
  • onest/duration of issue
  • relatives w ocular problems?
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13
Q

in terms of comfort, what are some questions to ask during history?

A

progressive?
static?
improving?

redness?
swelling?
discharge?
squinting?

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14
Q

general questions to ask while taking the patient history?

A
  • how long has client noticed problem?
  • any dec in activity or appetite?
  • if animal is blind, how long has the blindness been present?
  • ask about medication - what meds, how often, when was last dose
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15
Q

t/f

the pupillary light reflex (PLR) is an important test of vision

A

false

NOT a vision test b/c it does NOT require cortical perception of vision

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16
Q

what Cranial Nerves (CrNn) does PLR require?

A

CrNn 2 (afferent) and 3 (efferent)

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17
Q

what region of the brain does the PLR utilize?

A

midbrain

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18
Q

t/f

with significant retinal dysfunction, the PLR will not be present

A

false

the PLR may be present with significant retinal dysfunction

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19
Q

t/f

PLR will be absent with cortical blindless

A

false

PLR is NOT a test of vision and will be present with cortical blindness - cortical perception of vision NOT required for PLR

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20
Q

during a PLR test, what is the response called that occurs in the eye with direct light simulation?

A

direct PLR

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21
Q

during a PLR test, what is the response called that occurs in the opposite eye - the eye that is NOT receiving light stimulation?

A

consensual PLR

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22
Q

what is the pathway of PLR?

A

direct light stimulation -> retina and optic nerve (CrN 2) -> optic chiasm -> pupillo-motor fibers -> PS fibers, oculomotor N (CrN3) -> indirect or consensual PLR

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23
Q

how is the PLR altered in an excited or stressed dog?

A

it is decreased

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24
Q

how does iris atrophy affect PLR?

A

decreased or absent PLR

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25
Q

does age affect PLR?

A

yes - b/c age affects sphincter or muscle so PLR may be dec

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26
Q

what is the dazzle reflex?

A

intense blink response that occurs with light stimulation

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27
Q

t/f

the dazzle refllex is a good test of vision

A

false

the dazzle reflex does NOT require the visual cortex

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28
Q

the dazzle reflex is a reflex of what region of the brain?

A

subcortical reflex

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29
Q

what does the dazzle reflex look like?

A

light stimulus causes an involuntary blink

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30
Q

what CrNn does the dazzle reflex test?

A

CrNn 2 and 7

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31
Q

t/f

the dazzle reflex is one of the first reflexes to go in an animal that is deteriorating.

A

false

the dazzle reflex is one of the last things to go

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32
Q

is the dazzle reflex present with significant retinal dysfunction?

A

yes, it may or may not be preset with significant retinal dysfunction

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33
Q

what is the pathway for the dazzle reflex?

A

light stimulation -> retina and optic N (CrN 2) -> mid brain (most likely) -> facial N (CrN 7)

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34
Q

what tests evaluate vision in animals?

A

menace response
tracking behavior
maze test
placing reaction (cats)

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35
Q

what is the placing reaction in cats?

A

when initially removed from carrier and placed on table, their front paws should reach down for the table

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36
Q

what CrNn does the menace response evaluate?

A

CrNn 2 (afferent) and 7 (efferent)

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37
Q

t/f

the menace response is a learned response, therefore, is not present in young animals

A

true

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38
Q

around what age does a puppy develop a menace response?

A

14 wks old

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39
Q

how does the menace response differ btwn species that are precocious and species that are altricial?

A

menace response development occurs earlier in more precocious species

ex) horse - develops w/in 24 hours vs puppy - develops w/in 14 weeks

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40
Q

what are the vibrisa?

A

long hairs / eyelashes above the eyes

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41
Q

t/f

an important part of eliciting the menace response is to create air currents flowing past the animals eyes

A

false

do NOT create air currents - that interferes with the menace response b/c the animal responds to the air, and not the ‘menace’, or your hand

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42
Q

are both eyes evaluated together or is each eye evaluated separately during the menace response?

A

each eye is tested separately

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43
Q

what is the neural pathway of the menace response?

A

stimulus -> retina and optic N [CrN 2] -> thalamus -> occipital cortex -> frontal cortex -> cerebellum -> facial N [CrN 7) -> blink

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44
Q

how do tracking behavior tests work? what is a simple way, in a typical exam room, to evaluate his?

A

follow the animal’s ability to track an object / stimulus

drop a cotton ball and the animal’s eyes should follow it - however, some cats will not participate even if they are visual

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45
Q

how is maze testing carried out?

A

place objects randomly in front of the animal and see if they are able to navigate around them

may also dim light first to evaluate night vission

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46
Q

night vision issues often occur with what type of dzz?

A

retinal dzz

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47
Q

what should be evaluated during a maze test?

A

object avoidance

speed of navigation

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48
Q

what is the maze called when conducted in ambient light?

and in dim light?

A

ambient: photopic maze
dim: scotopic maze

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49
Q

what is the palpebral reflex?

A

the blink reflex elicited when the peri ocular area is touched

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50
Q

what CrNn does the palpebral reflex evaluate?

which is afferent and which is efferent?

A

afferent: CrN 5 [ophthalmic N]
efferent: CrN 7

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51
Q

what are the branches of CrN 5?

what region does each branch innervate?

A

maxillary Br: lateral canthus
ophthalmic Br: medial canthus
mandibular Br: base of ear

52
Q

what is the corneal reflex?

A

the blink response that is evaluated when the cornea is touched with a cotton wisp

53
Q

what CrNn are utilized during the corneal reflex?

which is afferent and which is efferent?

A

CrN 5 - afferent

CrN 7 - efferent

54
Q

what does the corneal reflex evaluate specifically?

A

corneal sensation

55
Q

what must NOT occur before the corneal reflex exam in order for the results to be diagnostic?

A

topical anesthetic [proparacaine] must NOT be given before the corneal reflex is evaluated

56
Q

what is the common name for the oculocephalic reflex?

A

doll’s eye reflex

57
Q

how is the oculocephalic reflex evaluated?

what is normal and abnormal?

A

move head up/down and right/left

normal: eyes should move from side to side or up/down as the head is manipulated
abnormal: no eye movement

58
Q

in what direction does the fast phase nystagmus occur?

A

in the direction of head movement

59
Q

what system/region if the brain is evaluated with the doll’s eye reflex test?

A

the vestibular system

60
Q

what CrNn are evaluated during the doll’s eye reflex test?

A

CrN 3 - oculomotor
CrN 8 - vestibulocochlear
CrN 6 - abducens

61
Q

when localizing neurophthalmic lesions, which 2 response tests evaluate for afferent function of CrN 2?

A

menace response and PLR

62
Q

when localizing neurophthalmic lesions, which 2 response tests evaluate for efferent function of CrN 7?

A

menace response and palpebral response

63
Q

what does the Schirmer tear test evaluate?

A

lacrimal lake
basal tear production
stimulated tear production

64
Q

what the normal measure from the Schirmer tear test?

A

over 15mm / 60s

65
Q

if btwn 10 and 15 mm / 60 seconds is measured from a Schirmer tear test, what condition is suspected?

what value confirms this condition?

A

KCS

less than 10 mm / 60 seconds

66
Q

what is the correct placement of the Schirmer tear test strips?

A

in the inferior fornix of the eye, central to lateral 1/3 of lower lid

must touch cornea in order to stimulate eye properly to produce tears

67
Q

if the Schirmer tear test strip falls out of the patient’s eye before the test is complete, how long must you wait until you run the test again?

why is this important?

A

wait 20 minutes

the lacrimal lake will have emptied and needs this time to refill

68
Q

what 2 tests must be conducted prior to topical anesthetic administration?

A

the corneal reflex and the Schirmer tear test

69
Q

why must anesthetic be applied after the Schirmer tear test and never before?

A

the anesthetic agent drops will add moisture to the eye, altering the tear test evaluation
AND stimulated tear test could not be measured if the cornea is desensitized

70
Q

how is a fluorescent stain test carried out?

A

moisten strip with eyewash and apply 1 drop to the eye

71
Q

what does a fluorescent stain test evaluate?

A

evaluates for presence of epithelial defects

72
Q

if there is an area of fluorescent stain in the eye after the test, what does that mean?

A

positive test - indicates a corneal defect in the epithelium - the epithelium on the surface of the eye has a defect so that the dye entered the corneal stroma

73
Q

what tissue does the fluorecein stain adhere to?

due to what what property of the tissue and the stain?

A

the stain is hydrophilic, and so is the corneal stroma, so they adhere to each other

74
Q

what does a negative fluorescein stain test look like?

why?

A

no dye uptake in the eye tissue

the die is hydrophilic and the epithelium on the surface of the eye is hydrophobic - so they do not adhere to each other

75
Q

what if there is a donut like appearance of the uptake of fluorescein dye in the eye?

why does the stain appear this way?

A

there is a defect that goes through the epithelium, into the corneal stroma, and all the way down to the endothelium [Descemet’s membrane]

the stain adheres to the corneal stroma, located beneath the surface epithelium, but NOT to the endothelium, which is located under the corneal stroma - this is hydrophobic, like the epithelium so does not take dye

76
Q

how is tonometry utilized?

A

digital pressure reading on eyes

77
Q

when should intra ocular pressure be measured?

A

every red eye with an intact cornea and sclera

genetic reasons - glaucoma risk
part of minimum ophthalmic database
monitoring uveitis cases
monitoring ophthalmic surgery cases

78
Q

when should intra ocular pressure NOT be measured?

A

if the eye is perforated or if there is perforation potential in the eye

descemetoceles
deep stromal or melting ulcers

79
Q

why should IOP of uveitis patients be measured?

A

b/c inflammation in the eye over time can lead to glaucome

80
Q

what is normal intraocular pressure in the dog? cat? horse?

A

dog: 12-15 mmHg
cat: 12-27 mmHg
horse: 17-28 mmHg

81
Q

how to obtain an accurate IOP measurement?

A

animal must be calm

avoid pressure to globe and lids - hold the orbital rim - or results may be altered

82
Q

t/f

when measuring IOP, you are more likely to get abnormally high measurements, so if you take multiple measurements, use the lowest reading as most accurate

A

true

83
Q

there should be less than ___ mmHg of IOP difference between the 2 eyes?

A

5

84
Q

what are 3 methods of tonometry?

A

Schiotz [indentation]
Tonopen [applanation]
Tonovet [rebound]

85
Q

what are pros to using Schiotz tonometry?

A
  • inexpensive

- accurate w practice

86
Q

what are cons to using Schiotz tonometry?

A
  • inconvenient in some spp
  • req practice
  • req horizontal cornea
  • difficult to clean
  • need conversion chart
  • affected by corneal dz
87
Q

pros to using applanation and rebound tonometry?

A
  • digital
  • convenient for small corneas
  • simple to use
  • vertical cornea ok
  • easy to clean
  • reproducible
88
Q

cons to using applanation and rebound tonometry?

A
  • expensive

- may need some servicing [minimal]

89
Q

what are some easy mistakes to make to keep in mind and avoid, while taking IOP reading?

A

pressure on neck [none from you or the leash/collar]
head position [should be physiologic position]
squinting dog
pressure on globe from improper lid retraction

90
Q

what is the protocol for using aplanation tonometry?

A
  • topical anesthesia
  • force to flatten corneal surface, gentle touch
  • accurate w many corneal abnormalities
  • easy to artificially elevate IOP: brachycephalics esp
  • calibrate prior to use or daily
  • use readings w coefficient of variation of less than 10% - measure btwn 3-6 readings
  • do not make cover too tight or too loose
91
Q

protocol for rebound tonometry with the tonovet?

A
  • electromagnetically propelled probe –> bounces off cornea

- calibrated for each species by manufacturer (dog/cat, horse, mice)

92
Q

what additional diagonstics might be recommended beyond the MDB for optho exam?

A
  • corneal cytology [topical anestiesia, gently scrape margin of ulcer with a blade, spatula or brush]
  • corneal culture - bacT, fungal, swab margin of ulcer but do NOT touch eyelids
93
Q

what is the Jones test?

A

look for fluorescin at nares - to demonstrate an intact NL duct

94
Q

how to carry out a nasolacrimal flush?

A
  • 5-10 mL syringe w eyewash
  • 24 gauge IV catheter w stylette removed
  • insert catheter in upper puncta
  • flush caniliculi and down NL duct
95
Q

what is the Seidel test?

A
  • evaluate for perforatioin
  • concentrated fluorescein
  • look for pale rivulets in fluorescein stain -> aqueous egress through perforation site
96
Q

during the ophthalmic exam, what does OS mean?
OD?
OU?

A 
OS = left [sinister] eye 
OD = right eye 
OU = both eyes
97
Q

what is the proper restraint for an animal undergoing ophthalmic exam?

A
  • gentle restraint, esp brachycephalics

- pressure at the base of the skull and under the chin

98
Q

what tools to you need to conduct an ophthalmic exam?

A
  • bright focal light source
  • dark environment
  • patient at eye level
  • magnification
  • anterior segment –> slit lamp, head loupes/transilluminator, otoscope
99
Q

what is diffuse illumination?

A

wide beam, low light

100
Q

what is retroillumination?

what structure in animals’ eyes allows this?

A

illuminate from behind

tapetum lucidum

101
Q

what is a good reference when deciding if one eye in a patient looks normal?

A

the patient’s other eye

102
Q

what should you evaluate during the distance examination of the patient?

A
  • is the patient visually guided by behavior?
  • facial symmetry?
  • symmetry in size / shape of orbit and globe?
  • eyelid conformation
  • discharge?
  • opacity?
103
Q

upon close examination of patient, what should you initially observe?

A
  • retropulse the globe

- is the patient painful upon opening the mouth?

104
Q

under what condition should you NOT retropulse the globe?

A

if there is an ulcer

105
Q

when holding the light source at a distance from your patient, what should you observe?

A
  • tapetal reflexes: highlight anisocoria and opacities in media
106
Q

bring the light close to your patient during the exam to observe what?

A
  • direct, oblique and retro illumination

anterior lesion back-lit by light from the tapetum or iris

107
Q

what is a MAJOR concept when localizing a lesion?

A

object overlay - anterior structures cover posterior ones

108
Q

what is one method to determine depth of lesion in the eye?

describe the process

A

purkinje images

slit beam creates optical cross section of the eye: tear film/cornea, black space (AC), anterior lens capsule, lens (smokey), posterior lens capsule

109
Q

what is the tyndall effect? when is it seen in the eye?

A

haze due to effect of colloid suspension, when particulates are illuminated by light

seen in anterior chamber when flare cells are present, often due to uveitis

110
Q

what is the center axis of rotation of the eye?

A

the center of the lens

111
Q

lesions anterior to the center of the lens move in which direction relative to the front of the eye?

A

in the same direction

112
Q

lesions posterior to the center of the lens move in what direction as the front of the eye?

A

in the opposite direction

113
Q

what are 2 ways to conduce a retinal exam?

A

indirect ophthalmoscopy [light source and lens] and direct ophthalmoscope

114
Q

what is ophthalmoscopy or funduscopy?

A

to look at - examine - the eye

115
Q

what is essential for a complete funduscopic exam?

A

mydriasis [dilated pupil]

116
Q

what short acting, fast onset [10-15 mins] drug can be used to dilate the pupil?

A

tropicamide

117
Q

what long acting, slow onset drug can be used to dilate the pupil?

A

atropine

118
Q

how does direct ophthalmoscopy work?

A
  • upright image
  • high magnification
  • easy to use
  • equipment readily available
  • shorter working distance
  • narrow field of view -> hard to view entire fundus
119
Q

what does the setting of the direct ophthalmoscope dictate?

A

the location of the lesion in the eye you can view

positive means more anterior region of the eye
negative means deeper into the eye
zero is good view of the fundus

120
Q

what is 0 on the ophthalmoscope mean?

A

good view of the fundus

121
Q

what does +8 on the ophthalmoscope mean? +12? +20D?

A 
8 = posterior lens
12 = anterior lens
20 = cornea lens
122
Q

what does indirect ophthalmoscopy tell you?

A
  • inverted image
  • wider field of view
  • stereopsis
  • req practice to master
  • low magnification
  • can visualize more of a fundus at a time
123
Q

what is important to keep in mind while using indirect ophthalmoscopy?

A
  • make sure lens is parallel to corneal surface
  • metal lens rim towards cornea
  • animal should “read writing” on lens rim
  • think tube
124
Q

for indirect ophthalmoscopy, what does 30D lens mean compared to a 40D lens?

A

30D is higher magnification

40D is lower magnification

125
Q

how does PanOptic tool compare to indirect and direct ophthalmoscopy?

A
  • upright image
  • field of view is btwn direct and indirect views
  • ease of use as with a direct, but more of the fundus can be visualized at a time

IP 11 Ophthalmology (13 decks)

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