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Ophthalmology > Review questions > Flashcards

Review questions Flashcards

1
Q

Is the cornea vascular?

A

No devascularized

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2
Q

Esotropia

A

Cross-eyed

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3
Q

Presbyopia

A

far sightedness due to loss of elasticity-usually a result of nuclear sclerosis

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4
Q

What happens if CN5 and CN7 are not working properly?

A

no blinking leads to dry eye

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5
Q

What should you do in a case of facial nerve paralysis?

A

suture eye shut so eye doesn’t dry out

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6
Q

What color eyes have no pigment?

A

blue

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7
Q

Define: Heterochromasia

A

eyes of different colors

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8
Q

Define: Symblepharon

A

Adhesion and fibrosis of conjunctival ulcerations. Most common cause is neonatal conjunctivitis in kittens

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9
Q

What does a blue cornea mean?

A

edema

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10
Q

Why is the limbus a common site for rupture?

A

it is a transition area which makes it an area of weakness

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11
Q

How many cones do animals tend to have? how about humans?

A

Animals tend to have 2 types blue and yellow-green or purple-blue and green (dichromatic), Humans have Blue yellow-green and red cones (trichromatic)

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12
Q

What is the role of the limbus in corneal healing?

A

contains stem cells that aid healing

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13
Q

What structure takes up the majority of the eye?

A

vitreous

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14
Q

Define: Pannus

A

CMI attack on cornea and uveal antigens. Plasma cells infiltrate cornea

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15
Q

Define: Endothelial dystrophy

A

Caused by abnormal nutrition, cornea not metabolizing normally becomes sick

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16
Q

What are the 4 layers of the cornea?

A

Epithelium, stroma, descemet’s membrane, endothelium

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17
Q

What determines visual field?

A

locationof the eyes, size and shape of the pupil

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18
Q

What is the main nerve going to the cornea?

A

CN5

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19
Q

What will you find at the healing site of a corneal ulcer?

A

limbal stem cells

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20
Q

How do you diagnose corneal ulcers?

A

Flourescein stain. Won’t stain normal retina

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21
Q

What does red in the cornea mean?

A

vessels

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22
Q

Yellow cornea means:

A

accumulation of cells

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23
Q

Dark cornea means:

A

it is ruptured

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24
Q

Shiny cornea means:

A

it is thin

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25
Q

What happens to the blood vessels of atrophic retinas

A

They disappear retina reverts to avascular tissue

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26
Q

What layer is responsible for most of the corneal thickness?

A

Stoma-90% of thickness

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27
Q

What does white in the retina mean?

A

abscess or neutrophils

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28
Q

Define: Bullous Keratopathy

A

severe generalized corneal edema. Can triple corneal thickness

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29
Q

Where do electrical signals of the eye go to?

A

Visual cortex-80% of fibers

Midbrain-20% of fibers

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30
Q

What part of the eye receives the most blood flow?

A

Choroid 85%

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31
Q

What forms the diaphragm in front of the lens?

A

Iris

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32
Q

What do animals see when they look at a tv screen. Why?

A

Bars moving up and down. They have better vision detection

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33
Q

Why do predators have more cones?

A

to have better visual acuity finding prey

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34
Q

What determines visual acuity?

A

number of ganglion cells

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35
Q

Define: Limbus

A

Cornea, conjunctiva and sclera meet at the limbus

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36
Q

What part of the eyes are vascular?

A

choroid, ciliary muscle, iris

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37
Q

Corneal Epithelium

A

outermost layer of the cornea

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38
Q

Define: Deep Corneal Ulcers

A

Exposes the decemas membrane

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39
Q

Define: Descemetocele Ulcer

A

Happens once decemas membrane is exposed

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40
Q

Define: Iris Prolapse

A

Occurs once descemas membrane is broken through. Then the iris comes up to try to plug the hole

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41
Q

What causes edema?

A

a failure in the corneal epithelium pump

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42
Q

Define: Sclera

A

Part of the outer fibrous tunic, supportive structure

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43
Q

Does the sclera have vascularization?

A

Yes

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44
Q

Is the Sclera hydrated or dehydrated?

A

hydrated

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45
Q

Define: Glare

A

condition in which blood vessels in iris start to leak when inflamed. Leak into anterior chamber and vitreous. Cloudiness in aqueous humor.

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46
Q

Visual Pathway

A

axons that form the optic nerve from the right eye go to the left side of the brain and vice versus

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47
Q

Reason dog orbit is incomplete?

A

Allows more jaw opening orbital ligament holds part of the eye. Important during enucleation

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48
Q

What kind of animals have complete orbits?

A

Herbivores

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49
Q

What kind of animals have incomplete orbits?

A

Carnivores

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50
Q

What is the inner tunic made of?

A

Retina

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51
Q

Corneal Epithelium Pump

A

An energy dependent pump whose purpose is to keep the cornea dehydrated

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52
Q

Define: Superficial corneal ulcers

A

affect epithelium only

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53
Q

Why would you want to keep the cornea dehydrated?

A

To keep it clear. Water does not allow it to be clear

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54
Q

What is the difference between the collagen patterns of the cornea and the sclera?

A

In the cornea collagen fibers are organized, in the sclera collagen fibers are disorganized

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55
Q

What two structures make up the middle tunic?

A

Iris and Uvea

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56
Q

Define: Retina

A

Part of the inner tunic. Converts photons to electrical energy. Starts the information processing

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57
Q

What is the purpose of the uvea?

A

acts as a shutter to control light entering the eye

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58
Q

What is the Uvea composed of?

A

Iris, ciliary body, choroid

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59
Q

What do zonules do?

A

They attach to ciliary bodies to help keep the lens in proper position. They are essentially little ligaments that are attached 360 degrees around the eye

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60
Q

Are ciliary bodies vascular?

A

Yes very vascular

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61
Q

Which enzyme is inhibited to treat glaucoma?

A

carbonic anhydrase

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62
Q

What enzyme is involved with the production of aqueous humor?

A

carbonic anhydrase

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63
Q

What produces aqueous humor?

A

cilliary process of the cilliary body

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64
Q

Define: Iris

A

Colored part of the eye

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65
Q

Define: Choroid

A

provides nutrients to the retina. High flow and low oxygen extraction

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66
Q

What kind of retinal vascular patterns do dogs and cats have?

A

Holangiotic

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67
Q

Define: Retinal detachment

A

Occurs between the pigmented layer and the photoreceptor layer

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68
Q

What is the most metabolically active tissue in the body?

A

Retina

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69
Q

Define: Fovea

A

avascular and pigmented

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70
Q

Where are the retinal capillaries most dense?

A

central retina

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71
Q

What are rods responsible for?

A

night vision and motion detection

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72
Q

What are cones responsible for?

A

Day and color vision, visual acuity. Most mammals are dichromatic

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73
Q

What are ganglion cells?

A

axons into the optic nerve

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74
Q

What kind of retinal vascular patterns do horses have?

A

Paurangiotic-very small blood vessesls that are hard to see.

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75
Q

Define: Lens

A

large structure behind the cornea for seeing up close and focusing light rays

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76
Q

How does the lens change shape?

A

through the constriction of ciliary muscles

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77
Q

What keeps lens clear?

A

dehydration

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78
Q

What happens when the lens experiences too much dehydration?

A

The lens can turn opaque

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79
Q

What can cause lens luxation?

A

If the zonules are weak/rupture the lens will shift. Terriers are at risk

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80
Q

Define: Glaucoma

A

Aqueous humor can’t leave through the angle, pressure builds up and angle collapses. Persistent pressure can lead to blindness and causes retinal and optic nerve disease

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81
Q

What muscles are involved in constricting the pupil?

A

ciliary muscles

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82
Q

Define: Pupil

A

Hole in the iris that regulates the amount of light getting inside

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83
Q

Define: Angle

A

Where the aqueous humor leaves the eye. Boundary between cornea and iris

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84
Q

What is a cataract?

A

Opacity of the lens or capsule, light is reflected back instead of passing through

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85
Q

Define: Nuclear Sclerosis

A

Age changing in the lens. Animals get it at about 6-7 years of age

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86
Q

Accommodation refers to:

A

the constricting/dilating of ciliary muscles depending on how close/far you need to see.

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87
Q

Define: Vitreous

A

Big space behind lens, in front of the retina

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88
Q

Define: Tapetum

A

Is used for seeing in the dark. Located in the choroid. Not present in all animals

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89
Q

Define: Tri-layered Tear film

A

Lipid-eyelids
aqueous- lacrimal gland and the third eyelid
Mucin-conjunctiva(extremely thin lymph-node)

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90
Q

Define: Tear function

A

Optically smooth surface, provide nutrients for the cornea, corneal immunity

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91
Q

What does the Nasal Lacrimal Duct do?

A

drains tears

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92
Q

Define: Epiphora

A

tears are draining down the face instead of the duct

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93
Q

Define: Decussation

A

Optic Nerve Fibers from right meet left, cross over chiasm

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94
Q

menace response

A

making a motion in front of the eye and having the animal blink

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95
Q

What is the purpose of the menace response?

A

testing vision, learned response

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96
Q

Cranial nerve II Optic purpose

A

for seeing the motion

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97
Q

Define: Deturgescence

A

dehydrate

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98
Q

Define: Horner’s syndrome

A

Loss of sympathetic innervation to the eye from otitis chest, neck disease. TE protrusion

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99
Q

Define: Haws syndrome

A

Nictitans protrusion, idiopathic, must rule out the presence of any underlying systemic/ocular disease

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100
Q

Define: Miosis

A

Means pupil is small

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101
Q

Reading PLRS

A

Visual with normal PLR: ok
Visual with absent PLR: efferent problem or pharmacological interference
Blind with normal PLR: something obstructing vision such as cataract
Blind with absent PLR: Problem with retina or optic nerve

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102
Q

Cranial nerve VII Facial

A

In order to blink in the reaction to it

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103
Q

Define: Pupillary Light Reflex (PLR)

A

Shine light at eye and pupil gets smaller (direct), evaluates the peripheral vision, tests retina and oculomotor nerves

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104
Q

Palpebral Reflex involves what nerves?

A

involves cranial nerve 5 and 7

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105
Q

Define: Electroretinography (ERG)

A

Used for evaluating electrical potential of retina in response to light stimulation

106
Q

Define: Mydriatic

A

Pupil is dilated, retinal disease or optic nerve disease is usually the cause. Glaucoma can also cause it

107
Q

What is the purpose of the third eyelid?

A

distributes tear film

108
Q

What is the third eyelid made up of?

A

Covered in conjunctive, made up of gland, ligament, cartilage.

109
Q

How does the third eyelid differ in cats and dogs.

A

Cats have voluntary control of it

110
Q

Blindness with dilated pupils

A

Lesion of retina, optic nerve, optic chiasm, or optic tracts before fibers exit to go to the oculomotor nerve. Peripheral blindness

111
Q

Blindness with normal pupils

A

Lesion of optic tract after fibers exit to go to the oculomotor nerve, optic radiation, or occipital cortex. Central blindess

112
Q

Define: Proptosis

A

Clinical condition due to trauma, strabismus is a clinical sign

113
Q

Define: Anterior uveitis

A

inflammation of the iris. Flare, leaky blood vessels due to inflammation , cloudiness in aqueous humor

114
Q

What makes up the uvea?

A

Iris, ciliary body, choroid.

115
Q

What comprises adnexa? (5)

A
  1. Supporting structures and tissues
  2. Orbit
  3. Eyelids
  4. Third eyelid
  5. Nasolacrimal system
116
Q

What nerves are involved with the corneal blind reflex?

A

A: (CN 5) - Trigeminal
E: (CN 7) - Facial and (CN 6) - Abducens

117
Q

What is the corneal blind reflex?

A

Stimulation of the cornea = closure of the lids and retraction of the globe

118
Q

What is the orbit?

A

The bony protection for the globe

119
Q

What are the two main branches of trigeminal that work with the eye?

A

Ophthalmic nerve, and maxillary nerve

120
Q

What is the innervation for the palpebral reflex?

A

Afferent arm: CN 5 - Trigeminal n.

Efferent arm: CN 7- Facial n.

121
Q

What is mydriasis? Sympathetic or parasympathetic?

A

Large pupil - sympathetic

122
Q

What is miosis? Sympathetic or parasympathetic?

A

Small pupil - parasympathetic

123
Q

What nerves are responsible for pupillary light reflex?

A

Afferent arm: retina - CN #2 Optic Nerve

Efferent arm: parasympatheticfibers along CN #3 oculomotor nerve

124
Q

What is anisocoria?

A

Unequal pupil size

125
Q

What is the primary purpose of the optic nerve?

A

Gathers electrical signals from the retina and carries them to the brain.

126
Q

What are the four layers of the cornea?

A

Epithelium, stroma, descemet’s membrane, endothelium

127
Q

What layers does a superficial ulcer go through?

A

Epithelium, but not into the stroma.

128
Q

What layers does a deep ulcer go through?

A

Through the epithelium and into the stroma.

129
Q

What layers does a descemetocele ulcer go through?

A

Goes through all layers except for the endothelium.

130
Q

How does the lens focus light?

A

By changing shape

131
Q

What is a direct response when concerning the pupillary light reflex test?

A

When shining a light into a pupil it constricts

132
Q

What is a consensual response when concerning the pupillary light reflex test?

A

When shining light into a pupil the opposite eye also constricts

133
Q

What is part of the afferent and efferent arms of the parasympathetic pathway?

A

A: 1. Photoreceptors 2. Optic n. 3. Optic Chiasm 4. Optic Tract 5. Pretectal nucleus
E: 1. Pre-ganglionic fibers 2. Oculomotor n. 3. Parasymp fibers along CN 3 4. Ciliary ganglion 5. Short ciliary nerve 6. Iris sphincter muscle

134
Q

What does visual with normal PLRs mean?

A

Animal is normal

135
Q

What does visual with absent PLRs mean?

A

Efferent / Motor problem

136
Q

What does Blind with normal PLRs mean?

A

Something oscuring vision (cataract ex.)

137
Q

What does blind with absent PLRs mean?

A

Retina or optic nerve issues

138
Q

What are the nerves involved with Lacrimation?

A

A: CN V: - Ophthalmic nerve
E: CN 7: - Facial nerve

139
Q

What is the Schirmer Tear Test?

A

(STT) Hook filter paper over the middle of the lower lid and it assesses tear production.

140
Q

What is innervated by sympathetic fibers?

A
  1. Upper eyelid
  2. Dilatory pupillae
  3. Third Eyelid
  4. Lower eyelid
141
Q

What is the primary purpose of the retina?

A

It has photoreceptors that when stimulated by light create electrical signals to send to the brain.

142
Q

What layers does an iris prolapse type ulcer go through?

A

All layers of the cornea.

143
Q

Which layer of the cornea is only one cell layer thick?

A

Endothelium

144
Q

What do you use to detect ulcers?

A

Fluorescein stain

145
Q

What does it mean if your cornea is white?

A

Abscess or necrosis - neutrophils are coming to the damage

146
Q

What is Horner’s syndrome?

A

Sympathetic nerve paralysis

147
Q

What are common causes of Horner’s syndrome?

A

Head trauma, neck trauma, orbit or middle ear issues

148
Q

What eye muscles does Oculomotor nerve (CN 3) innervate?

A

Dorsal, Central, and Medial rectus muscles. Also inferior oblique muscle

149
Q

What eye muscles does Trochlear nerve (CN 4) innervate?

A

Superior oblique muscle

150
Q

What muscles does Abducens nerve (CN 6) innervate?

A

Lateral rectus muscle and retractor bulbi muscles

151
Q

What does it mean if your cornea is blue?

A

Edema - water inside, endothelium is sick

152
Q

What is lipid keratopathy?

A

Fat in the eyes. Often associated with a high cholesterol diet in reptiles.

153
Q

What are two things associated with ocular surface failure?

A

Corneal ulceration and subepithelial keratomycosis

154
Q

What does it mean if your cornea is red?

A

Vessels in the cornea

155
Q

What is Pannus?

A

CMI attack on corneal and uveal antigens - worse in young dogs or dogs living at altitude. MHC Class II expression

156
Q

What are the external and internal layers of the retina supplied by?

A

E: choroidal circulation
I: retinal circulation

157
Q

What are rods responsible for?

A

Night vision, motion detection

158
Q

What does it mean if your cornea is dark?

A

The cornea is thin

159
Q

What does it mean if your cornea is shiny? (in animals with tapetum)

A

The cornea is thin because you see the tapetum reflection really easy.

160
Q

What are the cones responsible for?

A

Day vision, color vision, visual acuity

161
Q

What is an Electroretinogram?

A

Recording the electrical activity of the retina after a bright light flash.

162
Q

What is visual evoked potentials?

A

Recording of the electrical activity of the occipital cortex after a bright light flash

163
Q

Dazzle Reflex Test? Which nerves are involved?

A

Bright light in front of the eye - Eyelids closure
Afferent Arm: CN#2 Optic Nerve
Efferent Arm CN #6 Facial Nerve

164
Q

What is the PLR (Pulliary light reflex test)? Which nerves are involved?

A

Bright light in front of eye - pupillary constriction
Afferent: CN #2 Optic Nerve
Efferent: CN #3 Oculomotor Nerve

165
Q

What is the menace response test? Which nerves are involved?

A

Hand movements in front of eye to see if they blind or retract globe.
Afferent arm: CN #2 Optic Nerve
Efferent arm: CN #7 Facial Nerve, and CN #6 Abducens Nerve

166
Q

What is the autonomic nervous system responsible for? (6)

A
  1. Pupil size
  2. Pupillary light response
  3. Lacrimation
  4. Eye postion
  5. Eyelid positon
  6. Third eyelid position
167
Q

What is visual placing reaction?

A

Hold the animal in the air, advance to table, they will extend both forelimbs

168
Q

Dorsal rectus action and innervation?

A

CN 3 - oculomotor and elevates globe

169
Q

Ventral rectus action and innervation?

A

CN 3 - Oculomotor and depresses the globe

170
Q

Medial rectus action and innervation?

A

CN 3 - oculomotor and turns globe nasally

171
Q

Lateral rectus action and innervation?

A

CN 6 - Abducens and turns globe laterally

172
Q

Retractor bulbi action and innervation?

A

CN 6 - Abducens and retracts globe

173
Q

Dorsal oblique action and innervation?

A

CN 4 - Trochlear and intorts globe (inward rotation)

174
Q

Ventral oblique action and innervation?

A

CN 3 - Occulomotor and extorts globe (outward rotation)

175
Q

What is strabismus?

A

Lack of parallelism of the visual axes of the eyes.

176
Q

What 3 nerve usually cause strabismus and how does it manifest?

A
  1. Paralysis of Occulomotor - eyes turned laterally. 2. Trochlear - eyes rotated externally, 3. Abducens - eyes turned medially
177
Q

What is nystagmus?

A

Rhythmical oscillation of the eyeballs

178
Q

Innervation and action of levator palpebrae superioris muscle?

A

Oculomotor nerve (CN 3) : raises upper lid

179
Q

Innervation and action of Orbicularis oculi muscle?

A

Facial Nerve (CN 7) : Closes palpebral fissure

180
Q

Can animals see color?

A

Yes, but colors appear washed out.

181
Q

What is the purpose of the tapetum?

A

Doubles the probability of absorbency of light by the rods and cones.

182
Q

What does “visual field” i.e. size and shape of the pupil determine?

A

The angle of which the light can get into the eye, i.e. the angle of the visual field.

183
Q

What does vertical pupils offer for field of view?

A

Large binocular vision, small monocular vision, large blind spot

184
Q

What does horizontal pupils offer for field of view?

A

Small binocular vision, large monocular vision, small blind spot

185
Q

What are the layers of the retina? (10) Outer:

A

1: Retinal pigmented epithelium (RPE) next to choroid
2: Photoreceptor layer (rods and cones)
3. External limiting membrane
4: Outer nuclear layer
5: Outer plexiform layer
6: Inner nuclear layer
7: Inner plexiform layer
8: Ganglion cell layer - axons form the optic nerve
9: Nerve fiber layer
10: Internal limiting membrane - next to vitreous

186
Q

When something goes wrong at which point does it stop being optho and start being neuro?

A

After the chiasm.

187
Q

What are 4 common problems with vision?

A
  1. Opacity in cornea or lens
  2. Lack of retina Fc
  3. Optic nerve dysfunction
  4. Cortical problems
188
Q

What are three physical dysfunctions of the eye that can cause vision issues (blindness)

A

Retinal detachment, retinal tear, glaucoma

189
Q

Name four common vision tests

A

Obstacle course, cotton ball test, visual placing reaction, menace response test

190
Q

Innervation and action of Müller muscle?

A

Oculomotor nerve (CN 3) ; Raises upper lid

191
Q

What does round pupils offer for field of view?

A

Medium binocular vision, medium monocular vision, medium blind spot

192
Q

What is descemet’s membrane secreted by?

A

Endothelium

193
Q

Which nerves are the primary nerves for the cornea?

A

CN5 - trigeminal

194
Q

Are there nerves in decemet’s membrane?

A

NO

195
Q

What are 6 anatomic properties that contribute to transparency of the cornea

A

1: Lack of blood vessels
2: Lack of pigment
3: Non-keratinized anterior surface epithelium
4: Precise organization of the stromal febrile
5: Small size of the stromal fabrics
6: Relatively dehydrated compared to sclera

196
Q

What are 2 corneal functions?

A

1: Defection of light - 70% of the eye’s refractive or light bending power
2: Transparent to allow light rays to enter

197
Q

What does the epithelium act as a barrier to?

A

Precorneal tear film

198
Q

How thick is the stromal and is it cellular or acellular?

A

90% of the corneal thickness is stromal, and it is acellular

199
Q

What is the primary role of the endothelium?

A

To pump out fluids near the cornea to keep it dehydrated

200
Q

What is the outer coat of fibrous tunics made up of?

A

Cornea, limbus and sclera — conjunctiva merges with the epithelial layer of cornea

201
Q

What helps with ulcer healing?

A

Limbal stem cells

202
Q

What are two functions of the conjunctiva?

A

Externalized lymphatic tissues

Produces part of the tear film

203
Q

What are the three layers of conjunctiva?

A

Epithelial layer, sub-epithelial fibrous layer (Tendon’s), Episcleral space (potential space)

204
Q

Which layers of the cornea are most effected by bullous keratopathy?

A

Anterior stroma, and epithelium

205
Q

What is the limbus?

A

The transition zone between the cornea and sclera.

206
Q

What are the thinnest parts of the sclera in most species?

A

Equator and limbus

207
Q

What is the sclera? Is it vascular?

A

White in color with varying pigment. Sclera is vascular

208
Q

What makes up conjunctival epithelium?

A

Epithelium from the cornea merges with it.

209
Q

What is the average thickness of a cornea?

A

0.6mm

210
Q

What is the cotton ball test?

A

Drop a cotton ball nearby and see if they turn to look at it.

211
Q

Where are other places 20% of the electrical signals go in the brain?

A

To the midbrain where pupillary light reflex happens

212
Q

What does decussation mean?

A

Cross over - right eye goes to left side of the brain, and left eye goes to the right side of the brain.

213
Q

How do electrical impulses leave the retina?

A

Ganglion cell fibers

214
Q

What does facial nerve do?

A

Motor to eyelids, and other facial muscles

215
Q

What is transduction?

A

In the photoreceptors when they turn light energy into electrical energy

216
Q

What is a reflex response?

A

Contains two responses if normal: afferent (sensory) and efferent (motor)

217
Q

What are the four parts of the neurologic system for the eyes?

A
  1. Visual sensory system (Optic Nerve CN #2))
  2. Autonomic nervous system (sympathetic and parasympathetic)
  3. Oculomotor system: Oculomotor nerve (CN #3), Trochlear Nerve (CN #4), Abducens Nerve (CN #6), and Facial Nerve (CN #7)
  4. Trigeminal somatic sensory system (CN #5)
218
Q

What are four functional evaluations that don’t necessarily assess vision but test for a faulty mechanism?

A

Pupillary light reflex (PLR), Dazzle reflex test, electroretinogram (ERG), Visual evoked potentials (VEG)

219
Q

What are the steps of 80% of the electrical pathway from the eyes? (5)

A
  1. Retinal ganglion axons become optic nerve
  2. +/- Decussation at the optic chiasm
  3. Optic Tracts
  4. Ganglion cell synapse in the dorsolateral or lateral geniculate nucleus
  5. Output to visual cortex
220
Q

Types of conjunctiva graft (6)

A
  1. Island
  2. Bulbar Pedicle
  3. Tarsoconjunctival Pedicle
  4. Bridge Bulbar
  5. Advancement
  6. Complete bulbar
221
Q

How much more blood flow is to the ocular region than to the brain?

A

10 times more to the combined retinal and choroidal regions than that of the brain.

222
Q

What is symblepharon?

A

Adhesion and fibrosis of conjunctiva ulcerations. Can be caused by infection, chemical injury or trauma. Most common cause is neonatal conjunctivitis in kittens

223
Q

What is another name for severe generalized corneal edema?

A

Bullous keratopathy - usually edema from trauma

224
Q

What is conjunctivitis?

A

Inflammation of the conjunctiva

225
Q

What are the external layers of retina supplied by?

A

Choroidal circulation

226
Q

What are the internal layers of the retina supplied by?

A

Retinal circulation

227
Q

What is the total ocular blood flow for the retina?

A

4%

228
Q

What is the total ocular blood flow for the choroid?

A

85%

229
Q

Is the region that the rods and cones are in vascular?

A

No, the rods and cones are in an avascular region.

230
Q

What is the path from the globe of the eye to the brain?

A
  1. Exit globe
  2. Exit orbit via optic foremen
  3. Meets opposite nerve at optic chiasm
  4. Continues past chiasm on optic tracts
  5. 20% go to pretectal region
  6. 80% go to the LGN
  7. These axons continue posteriorly to cerebral cortex
231
Q

What does a normal cat retina look like? (3)

A
  1. Circular optic disk lacks myelin
  2. 3 major vessels leave the disc at the EDGE
  3. Tapetum is usually yellow or green
232
Q

What is PRA?

A

Progressive retinal atrophy

233
Q

What does a normal dog retina look like? (4)

A
  1. Tapetum - shiny surface
  2. Optic disc - white region with vessels on it
  3. Retinal vessels - on most of the optic disc
  4. Nontapetum - dark region
234
Q

Is the fovea vascular?

A

No, the fovea is avascular

235
Q

How does the optic nerve exit the eye?

A

Through the scleral lamina cribosa

236
Q

Which part of the retina has the most dense retinal capillaries?

A

Central retina

237
Q

What is the optic nerve composed of?

A

Axons of the retinal ganglion cells, and astrocytes and oligodendrocytes that act as support tissue

238
Q

What does an ERG recording system do?

A

Measures the electrical responses of the outer retinal layers

239
Q

What is axoplasmic flow?

A

Transfer of energy and information - interruption can lead to loss of vision!

240
Q

Can the optic nerve be repaired in mammals or birds?

A

Nope

241
Q

What are clinical signs of PRA? (5)

A
  1. night blindness to total blindness
  2. Reduced to absent photoreceptor layer (PLR)
  3. Tapetal hyper-reflectivity
  4. Retinal vessel attenuation
  5. Optic nerve atrophy, +/- cataracts
242
Q

What are some causes for retinal detachment? (5)

A
  1. Trauma
  2. Vitreal traction bands - pulls it off
  3. Serous effusions - pushes it off
  4. Retinal / choroidal / orbital neoplasia
  5. Retinal degeneration
243
Q

What are the four retinal vascular patterns?

A
  1. Holangiotic
  2. Paurangiotic
  3. Merangiotic
  4. Anangiotic
244
Q

What is the human retinal circulation pattern?

A

Single vessels

245
Q

What is LPCA?

A

Long posterior ciliary artery

246
Q

What is SPCA?

A

Short posterior ciliary artery

247
Q

Does the choroid have high or low - flow and oxygen extraction?

A

High flow low oxygen extraction

248
Q

What are the cranial nerves in order?

A
  1. Olfactory
  2. Optic
  3. Oculomotor
  4. Trochlear
  5. Trigeminal
    6 Abducens
  6. Facial Nerve
  7. Vestibulocochlear nerve
  8. Glossopharengeal
  9. Vagus
  10. Accessory
  11. Hypoglossal
249
Q

Are fovea and peripheral retina vascular or avascular?

A

Avascular

250
Q

Do retinal vessels have high or low - flow and oxygen extraction

A

Low flow and high oxygen extraction

251
Q

What is the hyaloid artery?

A

An artery that extends from the optic disc through the vitreous humor to the lens, which should be regressed before birth.

252
Q

What is the canine retinal circulation pattern?

A

Multiple vessels that are multidirectional

253
Q

What are the neural systems involved in normal vision and ocular health? (4)

A
  1. Visual sensory system
  2. Autonomic nervous system
  3. Oculomotor system
  4. Trigeminal somatic sensory system
254
Q

What are the innervation types for the cranial nerves?

A
  1. Sensory
  2. Sensory
  3. Motor
  4. Motor
  5. Both
  6. Motor
  7. Both
  8. Sensory
  9. Both
  10. Both
  11. Motor
  12. Motor
255
Q

Which cranial nerves are associated with eyes? (7)

A
  1. Optic #2
  2. Oculomotor #3
  3. Trochlear #4
    4, Trigeminal l#5
  4. Abducens #6
  5. Facial #7
  6. Vestibulocochlear #8
256
Q

What does optic nerve do?

A

Sensory - carries visual info from retina to cortex

257
Q

What does oculomotor nerve do?

A

Motor to several extraocular muscles and levator palpebrae superiors muscle, parasympathetic hitchhikers

258
Q

What does Trochlear nerve do?

A

Motor to superior oblique muscle

259
Q

What does abducens nerve do?

A

Motor to lateral rectus muscles and retractor bulbi muscles.

260
Q

What does trigeminal nerve do?

A

Sensory from eyelids, cornea, and lacrimal gland

261
Q

What does vestibulocochlear nerve do?

A

Vestibular component of ocular movements.

Ophthalmology (7 decks)

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