Anatomy & Exam Flashcards
1
Q
What bone make up the canine orbit
A
1) Lacrimal
2) Zygomatic
3) Frontal
4) Sphenoid
5) Palatine
6) Maxillary
2
Q
What additional bone makes ip the porcine and primate orbit
A
ethmoid
3
Q
What additional bone makes up the equine orbit
A
temportal bone
4
Q
T/F: Dogs have bone all the way around their eyes
A
False- they have an open orbit. nothing holding it in place if the soft tissue structure breaks
5
Q
What passes through the optic canal
A
1) Optic Nerve (CN II)
2) Internal ophthalmic artery
6
Q
What passes through the orbital fissure
A
1) Oculomotor Nerve (CN III)
2) Trochlear (CN IV)
3) Ophthalmic branch of CN V
4) Abducens (CN VI)
if affected- cavernous sinus syndrome
7
Q
Refers to deficits in more than one of the cranial nerves III, IV, V, and VI, as they are in close association in this region (floor of of calvarium where they leave the orbital fissure
A
Cavernous sinus syndrome
8
Q
With Cavernous Sinus Syndrome, what cranial nerves can be damaged
A
1) Oculomotor Nerve (CN III)
2) Trochlear (CN IV)
3) Ophthalmic branch of CN V
4) Abducens (CN VI)
all leave the orbital fissure
9
Q
What opening in the skull is assoiated with cavernous sinus syndrome
A
orbital fissure
10
Q
What passes through the rostral alar foramen
A
Maxillary artery
Maxillary branch of CN V
11
Q
What muscles open the eyelids
A
1) Levator palpebrae superioris m. (skeletal)
2) Mullers muscle (smooth muscle under sympathetic control)
12
Q
A structural muscle that elevates the upper eyelid. It’s innervated by the sympathetic nervous system
A
Mullers muscle
13
Q
What muscle closes the eyelids
A
Orbicularis oculi muscle (skeletal muscle)
14
Q
A test that used to detect obstruction of the nasolacrimal ducts
A
Jones Test
15
Q
What drains tears into the nose
A
Nasolacrimal duct
16
Q
What is the function of meibomian glands
A
produce oily components of the lipid layer of the tear film, with these components being secreted along the margins of the eyelids. The lipid layer of the tear film facilitates smooth blinking and attenuates the evaporation of lacrimal fluid
17
Q
mucous membrane that lines the eyelids and the globe
produces mucoid portion of tear film
has lymphoid tissue
A
conjunctiva
18
Q
What produces the mucoid portion of the tear film
A
conjunctiva
19
Q
What produces 65-70% of liquid tears
A
Lacrimal gland
20
Q
where is the lacrimal gland located
A
above the eye
21
Q
a t-shaped piece of cartilage that produces 30-35% of liquid tears
A
third eyelids
22
Q
What is a common site for foreign bodies in the eye?
A
conjunctival fornix
23
Q
What extra-ocular muscle rotates the top of eye ventronasally
A
dorsal oblique
24
Q
What extra-ocular muscle rotates the bottom of the eye dorso-nasally
A
ventral oblique
25
What muscle pulls the eye backwards, not present in humans
Retractor bulbi
26
What are the three layers that make up the globe
1) Fibrous tunic (cornea and sclera)
2) Vascular tunic (iris, ciliary body, choroid)
3) Nervous tunic (retina and optic nerve)
27
What 2 structures are a part of the nervous tunic of the globe
1) Retina
2) Optic nerve
28
What 3 structures are a part of the vascular tunic of the globe
1) Iris
2) Ciliary body
3) Choroid
29
What 2 structures are a part of the fibrous tunic of the globe
1) Cornea
2) Sclera
30
Anterior uveitis means inflammation of the
iris and ciliary body
31
posterior uveitis means inflammation of the
choroid
32
T/F: Cornea and sclera are made of different materials
False - same collagen, differ on their arrangements
Sclera- opaque collagen
Cornea- fibers perfectly arranged allows light to pass through
33
What species have cartilaginous plates in their sclera
reptiles and fish
34
What species have bone in their sclera
birds
35
the point in the fibrous tunic where the cornea meets the sclera
limbus
36
Is fluorescein stain hydrophobic or hydrophilic
hydrophilic
37
What layer of the eye does Herpes attack
the epithelium of the cornea- replicates fast
38
Is the epithelium of the cornea hydrophilic or hydrophobic
hydrophobic
39
What kind of epithelium does the cornea have
columnar and becomes keratinized squamous cells
40
What part of the cornea absorbs the stain in corneal ulcers
Stroma (it is hydrophilic) and the fluorescein stain is hydrophilic
41
T/F: fluorescein stain stains the epithelium of the cornea
False
Fluorescein is a water-soluble dye; owing to its lipid insolubility, it does not penetrate intact corneal epithelium. Epithelial erosions or ulcers, which expose the hydrophilic stroma, allow penetration and retention of the dye.
42
Is Descemets membrane hydrophilic or hydrophobic?
Descemet's membrane is hydrophobic. It's a thick, dense, relatively transparent, and cell-free matrix that separates the corneal stroma from the endothelium.
Does not take up fluorescein stain
43
What is the function of the corneal endothelium
transports water from the stroma into the anterior chamber
44
What makes the cornea clear
1) Regularity of the collagen fibers (compared to the sclera)
2) Very low cellularity
3) Lack of blood and lymph vessels
4) Relative dehydration
-stroma is hydrophilic (sponge)
-epithelium is hydrophobic barrier
-endothelium actively pumps fluid out of cornea
45
Why is it challenging to deliver drugs to the cornea
relative dehydration
-stroma is hydrophilic (sponge)
-epithelium is hydrophobic barrier
-endothelium actively pumps fluid out of cornea
46
What 3 structures make it so the cornea is relatively dehydrated
-stroma is hydrophilic (sponge)
-epithelium is hydrophobic barrier
-endothelium actively pumps fluid out of cornea
47
How many corneal layers do fish have
2
Scleral cornea
Dermal cornea
48
a scale that covers the eye of the snake
normally shed when the skin is shed
part of cornea
spectacle
49
What species is corneal vascularization normal in
big horn sheep and manatees
50
T/F: Descemetocele stains fluorescein
False- it is hydrophobic
51
How does superficial corneal pathology differ from deeper corneal pathology
Superficial: see branching vascularization
Deep: see dense vessels (hedge bush appearance) tells that you are concerned with a deeper issue like uveitis
52
What two features of the cornea bends light into the eye
1) Angle of incidence (curvature of cornea)
2) Density of the medium (tear film) bends the light
53
What does LASIK surgery do
uses a laser to change the curvature of the cornea
helps for near sighted patients because it is easier to decrease the curvature than it is to increase the curvature
54
a fluid filled space between the cornea and lens
Anterior chamber
55
what maintains the shape of the globe
aqueous humor in the anterior chamber
56
ultra filtrate that carries nutrients for the lens and cornea
maintains shape of globe
anterior chamber
57
the colorful part of the eye
the iris
58
what regulates the amount of light that enters the eye
controlled by iris sphicter and dilator muscles
size of the pupil
59
a ___________ pupil allows a more precise image to be focused on the retina
smaller
60
what creates aqeuous humor
ciliary body
61
dark, pigmented structures in a horse's eye that help reduce glare from bright light
corpora nigra
62
What are the different structures of the lens
1) Lens capsule (basement membrane)
2) Lens epithelium- makes cortex
3) Cortex
4) Nucleus
each layer is clear but as it gets more compact - it gets cloudy
63
a condition where there are multiple layers of lens packed together and the eye os cloudy
occurs in older animals
affects dim light vision
Lenticular sclerosis
64
what methods of accommodation do dogs and humans have
muscles in the ciliary body contract which pulls on the lens, causing the lens to stretch, which decreases the curvature of the lens
65
what methods of accommodation do birds have
ciliary muscles contract and push on lens, causing it to round up
66
What methods of accommodation do fish have
Retractor lentis moves the lens forward or backward to change focis
also have very round lens to make up for the loss of corneal refraction in aquatic environment
67
gel like structure between the lens and retina
made of glycoaminoglycans and some collagen, very few cells
can degenerate and become cloudy
Vitreous
68
how is the vitreous attached to the lens and retina
tiny ligaments, therefore vitreous can place traction on the retina and cause tears of detachments
69
what breeds are prone to vitreous degeneration
greyhounds and whippets
70
"Floaters"
when the vitreous degnerates and becomes cloudy
can lead to a retinal tear
71
Vitrous degeneration can lead to
retinal tear / detachments
72
neural tissue that is stimulated by photons
generates instaneous impulses that are modulated and sent to brain
brain then interprets this signal to determine color, contrast, brightness, movement, depth, and texture
Retina
73
millions of axons (of ganglion cells) extending from the retina to the brian
Retina
74
What are the two types of photoreceptors
1) Rods: assist with dim light vision, movement and contrast
2) Cones: color and detailed vision (Dogs have 2cones- Blue and Yellow-Green)
75
photoreceptors that assist with dim light vision, movement, and contrast
rods
76
photoreceptors that provide color and detailed vision
cones
77
How many types of cones do dogs have
2
1) Blue
2) Yellow-Green
this is similar to being red-green color blindness (Deuteranopia)
78
Deuteranopia
Red-green colorblind (canine color vision)
79
The reflective layer of the choroid (beneath the retina)
tapetum
80
What species have a cellular vs fibrous tapetum
Cellular: dogs and cats
Fibrous: horses and ruminants
81
is the tapetum a part of the retina or choroid
Choroid (beneath the sensory retina)
82
normal variation in the coloration of the eyes of dogs and cats that results in a lack of pigment in the non-tapetal fundus. This allows the choroidal vessels to be visible against the white sclera
subalbinotic
83
a dense network of blood vessels that covers the majority of the retina's light-sensitive region
entire retina has blood supply
present in dog, cat, human, ruminants
Holangiotic
84
a small, round, yellowish spot in the center of the retina at the back of the eye that's responsible for central vision, color vision, and fine details
present in human
macula
85
a type of retina where the entire retina has a blood supply
holangiotic
86
what species have a holangiotic retina
dog
cat
humman
ruminant
87
a retina where there are blood vessels over the miridian of the retina
merangiotic (rabbits)
88
what species have a merangiotic retina
rabbits
89
a retina type where the vessels are small and extend only a short distance from the disc.
present in horse, elephant, and guinea pigs
paurangiotic
90
What species hae paurangiotic
horses
elephants
guinea pigs
91
end-on vessels that feed retina can be visualized in an equine fundus exam
Stars of Winslow
92
Why are the Stars of Winslow relevant clinically
if a horse has a retinal detachment, blood supply is lost and the retina dies within minutes
however, dogs and cats keep their blood supply so if you can reattach the retina then everything will be ok
93
a term used to describe the absence of blood vessels in the retina of certain animals, such as birds and reptiles
Anangiotic
94
What species have an anangiotic retina
birds
reptiles
95
What cranial nerves are you testing with an ocular exam
II: Optic
III: Oculomotor
IV:Trochlear
V: Trigeminal
VI: Abducens
VII: Facial Nerve
VIII: Vestibulocochlear
2-8 are being tested
96
afferent nerve for menance and pupillar light reflex is
Optic Nerve (CN II)
97
what is the efferent pupillary light reflex nerve
Oculomotor (CN III)
98
What does oculomotor nerve innervate
Dorsal, vental, medial rectus
Ventral Oblique
Levator palpebrae superioris
99
What nerve innervates dorsal oblique
trochlear nerve
100
the only muscle that is controlled by the same side of the brain
Dorsal oblique (innervated by trochlear nerve CN IV)
101
afferent for palpebral reflex
trigeminal nerve (V)
102
what happens when the pterygoid muscle becomes inflammed
it is on the floor of the orbit, eye becomes exophthalmic
103
what happens when the pterygoid muscle becomes atrophied (from denervation of CN V- masticatory muscle)
enophthalmos
it is on the floor of the orbit s
104
What muscles does abducens nerve innervate
lateral rectus
retractor bulbi
105
efferent nerve for the palpebral
facial nerve
106
what carries parasympathetic fibers to the lacrimal gland, travel with the ophthalmic branch of CN V
facial nerve (CN VII)
107
Sympathetic stimulation the eye causes
1) Pupil dilation
2) Mullers muscle holds the upper eyelid up
3) Maintains some ridigity to the extra ocular muscles
108
What is the path of the nerve conducting sympathetic enervation to the eye
down the spinal cord from the brainstem where it exits at T1, T2, T3 in the brachial plexus then up the vagus nerve, synapsing in the cranial cervical ganglion, past the inner ear to the eye
109
what is ptosis
a dropping of the upper eyelid
seen with loss of sympathetic innervation to Mullers muscle (ex: Horners)
110
What should you use for sedation in equine eye examination
a2 agonist- detomidine, xylazine
opioid- butorphanol
111
What should you do for nerve blocks in equine eye examination
Auriculopalpebral- motor of upper lid (most important)
Frontal Nerve- sensation of the upper lid and cornea
fast acting, short duration (lidocaine, carbocaine)
112
blocks sensation to cornea and upper lid in the horse
frontal nerve block
113
What are different tools used in an ophthalmology exam
-Transilluminator
-Loupes
-Slit Lamp Biomicroscope
Fundoscopy
-Direct Ophthalmoscopy
-Pan-optic
-Indirect ophthalmoscopy
114
How can you test cranial nerve II
Pupillary light response
dazzle
menace
tracking
maze test
115
How can you test cranial nerve III
Movements of dorsal, ventral, medial rectus, ventral oblique, lebator palpebrae superiorsus, efferent PLR
116
How do you test CN V
Sensory to skin
globe cornea
mostly afferent
muscle of mastication
117
How do you test CN VIII
nystagmus, head tilt
118
How can you tell the eye is painful
Rubbing, squinting, tearing, red eyes
119
characterized by a difference in pupil sizes.
anisocoria
120
where will corneal vessels start
limbus
121
How should you examine the third eyelid
Retropulse the globe to evaluate
Prolapsed gland of third eyelid (cherry eye)
Scrolled cartilage (giant breeds)
Elevated in exophthalmos, Enophthalmos, Horner's, pain
122
What might cause protrusion of the third eyelid
exophthalmos
enophthalmos
horner's
pain
123
What should you evaluate on the irus
Texture, shape, color
-Atrophy
-Persistent Pupillary Membranes
-Neovascularization (Rubeosis irides)
-Synechia (anterior or posterior)
124
what is an alternative for Schirmer tear test
phenol red thread test
125
How do you differentiate cataracts from nuclear sclerosis
often need to dilate with tropicamide 1%
assess tapetal reflection with transilluminator
Nuclear sclerosis: hazy appearance to the center of the lens (can still see tapetal reflection)
Cataract: will completely block light
126
What are the different types of cataracts
1) Incipient (localized)
2) Immature (15-90%)
3) Mature (>90%)
4) Hypermature
127
allows fundus and lens to be evaluated
tropicamide 1%
128
When should you not dilate the eye with tropicamide 1%
-Increased intraocular pressure (glaucoma)
-questionable lens positon (luxation)
129
tapetum is part of the
choroid
130
where do you place the schirmer tear test strip
lateral 2/3rds of inferior eyelid
131
what is a normal schirmer tear test result
15mm wetting in 60 seconds
132
How do you perform a fluorescein stain?
do not touch dry strip to eye -moisten with saline first or mix with <1ml saline
1) Pattern of staining tells you ulcer location and depth
2) Can be used to check patency of nasolacrimal duct (Jones test)
3) Evaluate leaking aqueous (Seidels test)
133
Seidels test
fluorescein stain to evaluate the leaking aqueous
134
What are the different ways to test intraocular pressure
Schiotz: Indentation - Requires a patient patient
Tonopen: Applanation - Require Proparocaine
Tonovet: Rebound (NO proparocaine)
135
What happens after chronic chorioretinitis
retinal atrophy- results in hyper reflective
136
What is normal intraocular pressure
8-25mmHg
No more than 3-5mmHg discrepancy between eyes
not a diagnosis
technique is everything- any pressure on the neck or eyelids may alter the results
137
There should be no more than _______ intraocular presure discrepancy between eyes
3-5mmHg
138
IOP is elevated in ______ but decreased in ____________
elevated in glaucoma
decreased in uveitis and old age
139
evaluates the iridocorneal angle
gonioscopy
140
should be does for corneal ulceration
cytology +/- culture
141
can evaluate the globe and retrobulbar space
ultrasound
142
tests the electrical function of the retina
electroretinogram
143
What cranial nerve does touching the cornea do?
Trigeminal (afferent)
Abducens (efferent)
144
What cranial nerve does touching the palpebral do?
Trigeminal (afferent)
Palpebral (efferent)
144
Dogs with cranial nerve III damage, what way can the eye move
laterally (that is controlled by abducens VI)
145
Dogs with CN III damage, will the pupil be dilated or constricted
dilated (lack of parasympathetic input to the eye)
146
direct PLR
ipsilateral illumination
147
indirect PLR
contralateral illumination
148
