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NMSK > Eye > Flashcards

Eye Flashcards

1
Q

What is the scientific name for the third eyelid

A

Nicitaris gland

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2
Q

What is the function of the mebomian glands

A

To create lipids that form part of the tear film

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3
Q

What does the levator palbebrae superioris do

A

Keeps upper eyelid elevated

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4
Q

What does the orbicularis oculi do?

A

Muscle to close eyelid

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5
Q

What is the function of the lacrimal punta

A

Releases tears

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6
Q

What is the limbus of the eye

A

Zone between the iris and the sclera

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7
Q

What is the sclera of the eye

A

White of the eye that helps maintain shape of the eye

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8
Q

What is the lateral canthus of the eye

A

Corner of eye on lateral part of face

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9
Q

What is the medial canthus of the eye

A

Corner of eye in middle of the face

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10
Q

What is the fundus of the eye

A

Back part of the inside of the eye

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11
Q

What is the function of the tapetal fundus

A

Reflects light hack the retina so in low light conditions better vision

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12
Q

What is in the fundus

A

Retina
Fovea
Choroid
Optic disk
Blood vessels

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13
Q

What is the function of the choroid and where is it

A

Forms vascular layer of eye (dense supply of blood vessels)
between sclera and retina
Provides o2 and nutrients to retina

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14
Q

What is exophthalmos and what does the globe look like

A

Abnormal production of eye from orbit
Globe is a normal size but protruding

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15
Q

What is enophthalmos and what does the globe look like

A

Abnormal recession of the eye within the orbit
Normal size/ appearance of eye but sunken

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16
Q

What is hydrophthalmos and what does the globe look like

A

Enlargement of the globe and its producing, so globe looks abnormal

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17
Q

What is microphthalmos and what does the globe look like

A

Congenitally (at birth) abnormal small eye
Normal position of eye within the socket

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18
Q

What is the function of the orbit

A

It’s the cavity within the skull that encloses the eye
Protects the eye and separates eye from cranial cavity (brain)
Contains Foramina within walls to provide a pathway for blood vessels and nerves to reach eye

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19
Q

What is the orbit like within domestic species

A

Bone come with soft tissue floor

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20
Q

What is the orbit type for a herbivore

A

Closed/ complete

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21
Q

What is the orbit type for a carnivore

A

Open/ incomplete

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22
Q

What is the composition of the lateral wall in the orbit of the herbivore

A

Bone
Zygomatic and frontal bones are fused

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23
Q

What is the composition of the lateral wall in the orbit of the carnivore

A

Soft tissue
Lateral orbital ligament

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24
Q

What is the visual field like for herbivores and why

A

Wider monocular
Narrower degree of binocular (3D vision)
Eyes are on the side of the head
It’s easier to see predators coming

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25
Q

What is the visual field like for carnivores and why

A

Narrower monocular
Wider degree of binocular vision (3D)
Gives a greater depth perception to allow animal to be able to have greater accuracy before the jump to catch peey

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26
Q

Why do carnivores have an open/ incomplete

A

To be able to open jaw wider

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27
Q

What is brachycephakic breeds like

A

Shorter nose and flat faced
Shallow orbit and minimal protection

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28
Q

What are mesocephalic dogs like

A

Head of medium proportions
Medium depth orbit and medium protection

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29
Q

What are Dolicocephalic dogs like

A

Relatively long head
Deeper eye sockets and greater degree of protection offered

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30
Q

How many bones make up the orbit

A

5-7 depending on species

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31
Q

What makes up the medial limit of the bonds orbit and what is the function

A

Frontal bone
Separates orbit from nasal cavity

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32
Q

What bone is on the dorsal limit of the bony orbit

A

Frontal bone (frontal sinus)

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33
Q

What bones are on the rostral and lateral limits of the bony orbit

A

Zygomatic
Lacrimal
Maxillary bones

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34
Q

What bones make up the caudal limit of the bony orbit

A

Sphenoid bone

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35
Q

What is the function of the sphenoid bone

A

Optic canal and orbital fissure pass through here

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36
Q

What soft tissue is on the ventral floor of the orbit

A

Pterygold muscles

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37
Q

What is on the dorsolateral limit of the soft tissue or it

A

Temporal muscle
Orbital ligament

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38
Q

What is on the rostral and lateral limits of the orbit

A

Masseter muscle

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39
Q

What goes through the optic foramen

A

Optic nerve

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40
Q

What goes through the orbital fissure

A

Opthalmic nerve
Trochlear nerve
Abductees nerve
Oxulamotor nerve
Internal opthalmic artery

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41
Q

What muscles does the oculomotor nerve innervate

A

Dorsal rectus
Medial rectus
Ventral rectus
Ventral oblique

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42
Q

What muscles does the abductens nerve innervate

A

Lateral rectus
Retractor bulbi

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43
Q

What does the trochlear nerve innervate

A

Dorsal oblique

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44
Q

What is the intraconal space

A

Within space defined by four rectus muscles and periorbital fascia sheath
Shaped like an ice cream cone

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45
Q

What structures are within the intraconal space

A

Optic nerve and nerves supplying muscles around eye
Vesssels
Smooth muscles
Fat
Orbital lacrimal gland

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46
Q

What provides blood to the eye

A

The ophthalmic artery, which is derived from the internal carotid artery

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47
Q

What is the venous drainage of the eye

A

Through vortex veins and orbital venous veins
Can go through ophthalmic vein
Eventually all drains into the external jugular vein

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48
Q

What is anisocoria

A

Unequal pupil size

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49
Q

What is miosis

A

Excessive constriction of pupil

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50
Q

What is mydriasis

A

Dilation of the pupil

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51
Q

What is strabismus

A

Abnormal alignment of the eye

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52
Q

What is nystagmus

A

Rapid involuntary eye movement

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53
Q

Why do animals often stop eating with eye pain

A

Because the ramus (jaw bone) moves towards the glove when the mouth is opened

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54
Q

What is the vitreous humour and its function

A

Clear gel that fills the space between the lens and the retina of the eyes
Shock absorber
Removes waste products
Maintains intraconal anatomy

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55
Q

What did the lens develop from

A

The surface ectoderm,
Then invaginates, which forms lens vesicle and optic cup

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56
Q

What supports the lens

A

The lens zonules

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57
Q

What does the lens sit in

A

Hyaloid fossa

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58
Q

What supports the iris anteriorly

A

Lens

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59
Q

Which side of the lens capsule is thicker and why

A

Front lens becomes thicker as anterior lens epithelium secretes lens capsule

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60
Q

What are lens fibres like

A

Have thick centres and tapered ends
Meet in a Y shaped pattern, they can’t meet in a single point as not enough space

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61
Q

How does the lens age/ grow

A

Concentric growth
New lens fibres form from anterior epithelium and lens equator and wrap around embryonic nucleus

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62
Q

How do older fibres compare to younger fibres

A

Denser and less transparent

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63
Q

How does the fetus lens get nutrition

A

Via the tunica vasculosa lentils
(Blood vessels like hyaloid artery)

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64
Q

Why does the adult lens have no blood supply or nerves

A

It would obstruct vision

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65
Q

How does adult lens get nutrition

A

Aqueous humour

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66
Q

What would cause a cataract to develop in eye

A

If any amount or type of protein to change in lens

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67
Q

What is the lens composed of

A

35% protein
65% water

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68
Q

What is the function of the lens

A

1/3 refractive power of eye
Accommodation (more in birds than herbivores_
Blocks UV light from retina

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69
Q

What is the vitreous humour made from

A

99% water
1% protein/ cells

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70
Q

What is persistent pupillary membranes

A

Failure of regression of anterior portion of the tunica vasculosa lentils

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71
Q

What is the oldest part of the lens

A

Nucleus

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72
Q

What is nuclear sclerosis

A

Eyes appear greyish blue as animal ages, older fibres are denser and less transparent than younger fibres of lens

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73
Q

How would you exam for a nuclear sclerosis

A

Distant direct ophthalmoscopy
Look at tapetal reflection

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74
Q

What is a cataract

A

Any opacity of lens or its capsule

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75
Q

What are the 5 main causes of cataracts

A

Trauma
Metabolic (diabetes)
Other introduce disease
Hereditary (inherited)
Senile (old age)

76
Q

What are the 4 types of classification for cataracts

A

Age
Aetiology (cause)
Position
Extent

77
Q

How does diabetes cause cataract

A

If not enough enzyme hexokinase (which converts glucose to glucose 6 phosphate) then glucose is converted to sorbitol
Sorbitol causes water to be absorbed into lens and lens fibres smell and then white

78
Q

What further implications can cataracts cause

A
  1. Vision problems
  2. Problems on ocular health like lens induced uveitis (when proteins break out of lens and eye reacts as not used to those
79
Q

What structure is attached to the lens equatot to hold it into position

A

Lens zonules

80
Q

What is lens subluxstiom

A

When the lens falls out of place, usually due to trauma, can be forwards or back

81
Q

What is the problem of an anterior lens lucation

A

Lens blocks the flow of the aqueous humour
Pressure inside eye increases rapidly to cause an acute secondary glaucoma

82
Q

What are the 3 layers of the eyelid

A

Haired eyelid skin on the outer surface
Muscles containing meibomian glands
Palpebral conjunctiva

83
Q

What is the palpebral fissure

A

The opening between the eyelids

84
Q

What muscle controls eyelid closing and what innervates it

A

Orbicularis oculi
Facial nerve

85
Q

What muscles control eye,id opening and what innervates them

A

Levator palpebrae superioris (oculomotor nerve)
Muller muscle (sympathetic innervation)
Facial nerve innervates other muscles

86
Q

What nerves give sensation to the eyelid

A

Branches of opthamalic and maxillary nerve from trigeminal

87
Q

How many meibomian glands are there per eyelid

A

20-40

88
Q

What do the meibomian glands produce

A

Meibum (lipid part of tear film)

89
Q

What is the function of eyelids

A

Protects eye from gray mace
Distributes and drains tears (hydration and nutrition to ocular surface)
Removes debris from ocular surface

90
Q

What is the anatomy of the third eyelid like

A

Central shaped t cartilage
Conjunctiva covering bulbs and palpebral surface
Nicititajs gland at base

91
Q

What is the function of the nictitans gland

A

Produces tear film
Protects ocular surface
Distributes tear film
Contains immunologic secreting plasma cells

92
Q

What blood vessels in eye can you normally see

A

Conjunctival vessels

93
Q

What blood vessels in eye should you be concerned if you see

A

Episcleral vessels (as they as deeper and only usually seen during inflammation0

94
Q

What is the function of the conjunctiva

A

Protects ocular surface
Goblet cells produce mucin for tear film
Many lymphocytes present

95
Q

How does the tear drainage system work via the nasolacrimal system

A

Tears drain via upper and lower lacrimal puncta
Then into lacrimal canniculu and lacrimal sac
Then into nasolacrimal duct and out nose

96
Q

How should an examination of the eyelids work

A

Check for blepharospasm (ocular pain) and eyelid conformatiom
Check blinking
Look for masses, extra eyelids. Swellings
Tear staining to check for extra tears productiom

97
Q

What is entropian

A

Inward turning of parts or all of the eyelid

98
Q

What is extropian

A

Diversion or outward turning of the eyelid

99
Q

What is distichiasis

A

Extra eyelashes emerging from meibomian glands

100
Q

What is ectopic cilia

A

Cilia arising from near or inside meibomian gland, through conjunctival surface of the eye

101
Q

What is trichiasis

A

Hair located in the right place but facing wrong way towards ocular surfaces

102
Q

What are the three layers of the eye

A
  1. Fibrous outer layer (sclera and cornea)
  2. Vascularised Middle layer (uveal tract)
  3. Neuroectodermal inside layer (retina and optic nerve)
103
Q

How thick is the tear film

A

7-8um

104
Q

What are the four components of tear film

A

L- lipid- limits evaporation
A-aqueous- most of volume
M- mucin- aids spread and adherence of tear film
E- epithelium

105
Q

What produces the aqueous layer of the tear film that

A

Orbital gland- 70%
Nicitans gland- 30%

106
Q

What is the function of the tear film

A

Provides nutrients and oxygen to ocular surface
Provides smooth and transparent surface
Protects ocular surface from bacteria
Lubriavtes ocular surface

107
Q

What are the 3 layers of the sclera

A

Lamina fusca
Sclera stroma
Episclera

108
Q

What covers the anterior portion of the sclera

A

Bulbar conjunctiva

109
Q

What is the limbus and its function

A

Where cornea, sclera and bulbar conjunctiva merge
Source of stem cells

110
Q

What is Tenon’s capsule

A

Connective tissue sheath
Connects bulbar conjunctiva to underlying sclera

111
Q

What is the episclera

A

Dense highly vascularised layer
Blends with tenons capsule

112
Q

How thick is the cornea

A

0.5-0.8mm

113
Q

What are the 3 layers of the cornea

A

Epithelium
Stroma
Endothelium

114
Q

What is the structure/ function of the epithelium level

A

Stratified squamous epithelium
5-7 cell layers in dogs
12-15 cell layers in horses
Tight junctions between cells act as a permeability barrier, water can’t get into the stroma

115
Q

What is th4 stroma of the cornea like

A

90% of corneal thickness
Regular layers of collagen

116
Q

What is the corneal endothelium like

A

One cell thick layer
NA/K+ pump ions frok stroma into aqueous humour

117
Q

What keeps the cornea transparent

A

Smooth optical surface
Regular arrangement of collagen fibres
Ow cell density
No blood vessels/ nerves
Dehydrated

118
Q

What is th4 function of the cornea

A

Refract and transmits the light
Protection (chemical barrier )
Tensile strength

119
Q

How can you examine tear film

A

Corneal reflection
Schimear test

120
Q

How can you examine the cornea

A

Darkened room
Look for irregularities, opacificarion, vascularisation, pigmentation
Can use fluroscean stainign

121
Q

How does fluroscein staining work

A

Orange dye that turns green in alkaline tears
Ahears to hydrophilic tissues such as exposed stroma
Can diagnose corneal ulcers

122
Q

What is the fancy name for dry eye

A

Keratoconjunctivitis

123
Q

How can you diagnose keratoconjunctivitis

A

STT less than 15mm/min
Corneal ulceration/ vascularisation

124
Q

What is an ulcer

A

A discontinuation or break in the membrane

125
Q

What is a corneal ulcer

A

break in continuity of corneal epithelium with exposure of underlying stroma

126
Q

What can cause corneal ulcers

A

Trauma
Eyelid abnormalities
Eyelash lesions
Degenerations
Infections

127
Q

What are the three types of ulcers

A

Superficial ulcer
Stroma ulcer
Descenmetaote

128
Q

What are desmetaceole ulcers

A

Ulcers that go down to descements membrane
Flurocien stain isn’t taken up at DM

129
Q

How is the cornea regenerated

A

Basal epithelial cells at limbus

130
Q

How is an epithelial wound healed

A

Cell proliferation, migration and adhesion
Faster if basement membrane remains intac

131
Q

How is stroma wound healed

A

Starts once re-epithelialisation is complete
Fibroblasts migrate in & lay down new collagen
Requires vascularisation
Results in scar tissue: remodelling over time

132
Q

What could a blue cornea be a sign of

A

Oedema

133
Q

What could a red cornea be a sign of

A

Vascularisation

134
Q

What could a black cornea be a sign of

A

Pigment

135
Q

What could a white cornea be a sign of

A

Scarring, lipid, calcium,

136
Q

What are the 3 components of the uveal tract from front to back

A

Iris
Cilary body
Ciliary body

137
Q

What is the cilary zone of the iris

A

The peripheral part of the iris

138
Q

What is the pupillary zone

A

The centre part of the iris

139
Q

What is the transition part of iris (between the ciliary and pupillary zone)

A

Collarette zone

140
Q

What is the blood supply to the iris like

A

Incomplete artieriole circle
Anterior and posterior cilary arteries
Blood vessels come in at 3 and 9 o clock

141
Q

What is the anatomy of the iris like

A

Stroma:
Made of fibrous collagen bundles
Pigmented and non pigmented sections
Blood vessels
Iris sphincter muscle (iris constrictir)

Front: MOT epithelium, (stroma border layer)
Back: epithelium level

142
Q

What are the masses seen on the eye of horses/ ruminants called

A

Corpora migrant (horses)
Granula indica (ruminants)

143
Q

What is the function of the iris

A

Controls the amount of light that enters the eye
When Irma part of blood ocular layer

144
Q

What is the cilary body comprised of

A

Smooth muscle
Connective tissue
Blood vessels
Nerves
Double epithelium layer

145
Q

What are pars plicata?

A

Folded part of cilary processes

146
Q

What is the para plana

A

Flat part of ciliary body

147
Q

What are zonular fibres

A

Supports the lens and keeps it in the middle of the pupil
Originates within the tips and valleys of ciliary processes

148
Q

What is the function of the ciliary body

A

Production and drainage of aqueous humour
Anchors lens zonules and provides accommodation by changing shape of the lens
Blood aqueous layer

149
Q

What processes allow aqueous humour to be produced

A

Diffusion
Ultrafiltration
Active secretion

150
Q

What is the function of aqueous humour

A

Supplies nutrients and remove waste from avascular parts of eye (cornea, trabecular network, lens, anterior vitreous)

151
Q

What is the aqueous humour made from

A

98% water
Protein, lactate, glucose, amino acids

152
Q

What is the function of the choroid

A

Blood supply for retina
Blood- ocular barrier
Includes the tactum

153
Q

What ensures the blood ocular barrier

A

Tight junctions between epithelium cells
All blood vessels are non fenestrated

154
Q

What are the mechanisms to allow ocular immune privilege

A

Blood-ocular barriers: limiting access to eye
Absence of lymphatic pathways: limiting access to lymphatic tissues
Aqueous humour composition: ascorbic acid and other anti-oxidants
Immunomodulatory ligands on intraocular cells (esp pigmented epithelial cells)
Indigenous, tolerance-promoting antigen-presenting cells

155
Q

How many layers does the choroid have

A

5

156
Q

How would you examine the anterior uvea

A

Dark room
PLR
Intraocular pressure

157
Q

What are the clinical signs of uveitis

A

White blood cell migration
Increased blood supply
Increased permeability of vessels
Pain
Red eye
Miosis
Low intraocular pressure

158
Q

What are secondary consequences of uveitis

A

Synechia (iris is sticky and things get attached to it)

Secondary glaucoma
Cataract
Retinal detachment, retinal degeneration, optic nerve atrophy
Vision loss

159
Q

What could cause uveitis

A

Trauma
Infection
Immune mediated
Metabolic
Neoplasia
Idiopathic

160
Q

What are some causes causes of secondsey glaucoma

A

Lens luxurious
Uveitis
Eoplasia

161
Q

What are some signs of a glaucoma

A

Red eye
Pain
In ordeal oedema
Fixed dilated pupil
Vision loss

162
Q

What is a normal IOP in animals

A

Dogs- 10-25mmHg
Rabbits- 15-20mmHg

Difference in more than 8 is abnormal

163
Q

What are the three different devices to measure IOP

A

Schnitz tonimotry
Rebound tonometry

App,a nation tonometry

164
Q

Where is the retina located

A

Neural layer
Outside the vitreous humour
Inside the choroid then sclera

165
Q

How many layers do the retina have

A

10

166
Q

What is the simplified version of the retina with the two layers

A

Neurosensoru layer
Retinal pigment epithelium,

167
Q

What are the 4 main aspects of the neurosensory layer

A

Optic nerve fibres
Ganglion cells
Bipolar cells
Photoreceptors

168
Q

What is the structure of the retinal pigmented epithelium like

A

Outmost single layer of cells in retina
Lies in front of the tapetum
Has pigmented and non pigmented areas

169
Q

Where are the photosensory receptors

A

In the RPE

170
Q

What is the function of the RPE

A

Recycling “used” photopigments
Phagocytosing and renewing photoreceptor outer segments
Storing vitamin A
Melanin pigments (non-tapetal i.e. pigmented areas only) absorb stray light and scavenge free radicals
Forming part of blood-retinal barrier
Phagocytic role in retinal inflammation

171
Q

Where are the rods and cones

A

In the outer nuclear layer of the neurosensory layer

172
Q

What are rods and cones

A

Specialised cells that transduce light energy into electrical signals
Cones- colour and visual acuity
Rods- night vision

173
Q

How does phototransduction work

A

Light energy causes opsin to change shape and then binds to transducin, causes hyper polarisation and releases neurotransmitter
Travels to ganglion cells along nerve axons to optic nerve

174
Q

What is the function of the retina

A

Absorbs light rays and converts light energy into electrical energy which travels as nerve impulse up optic nerve to visual cortex

175
Q

What are the three regions of the optic nerve

A

Intraocular portion
Can be directly observed in vivo
Retrobulbar portion (in orbit)
Intracranial portion

176
Q

Is optic nerve myelinated or not

A

Dog- yes
Cat- no

177
Q

What is the fundus

A

the portion of the posterior segment of the eye that is viewed with the ophthalmoscope

178
Q

What is the blood supply to the retina like

A

High metabolic rate: dual blood supply
Inner retina: retinal blood vessels
Outer retina: choroidal blood vessels

179
Q

What is Holangiotic

A

retinal blood vessels supply whole retina e.g. dog, cat, cow, sheep, goat

180
Q

What is Paurangiotic

A

retinal blood vessels supply a small focal area of retina e.g. horse

181
Q

Why can tapetum be seen

A

Retina is translucent

182
Q

What is tapetum and is]to function

A

Part of choroid behind retina
Shiny reflective layer
Reflects light rays to retina gets rays twice

183
Q

What can vary in the fundus colour and why

A

Colours in choroid +/- tapetum and RPE vary according to coat and iris color

184
Q

If the retina has thinned, would you expect the tapetum to appear more or less reflective on ophthalmoscopy?

A

Less

185
Q

Where is the retima stromglu attached

A

Around the optic disc
Ora ciliaris retinae (peripheral retina

186
Q

Where does detachment of the retina occur

A

between neurosensory retina and RPE

187
Q

What are the main 6 causes of retina detachment

A

Systemic hypertension, e.g. geriatric cats
Congenital, e.g. collie eye anomaly (inherited retinal disease)
Trauma
Inflammation
Neoplasia
Complication of lens luxation or chronic cataract

NMSK (47 decks)

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