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Pathology II > LEC 8 - Eyes > Flashcards

LEC 8 - Eyes Flashcards

1
Q

What are the four possible entry into the cornea?

A

Destruction of corneal epithelium

Penetration of corneal stroma

Diffusion intro stroma via limbal blood vessels

Injurt to corneal endthelium

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2
Q

What are three examples that cause injury to the corneal endothelium?

A

Gluacoma

Lens luxation

Leukocyte mediated injury

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3
Q

What is the main method by which there is entry into the uvea?

A

Hematogenous

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4
Q

What are the three hematogenous routes that go into the uvea?

A

Toxins

Infectious agents

Neoplastic emboli

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5
Q

What are the methods of defense in the cornea?

A

Intact corneal epithelium

Leukocytes

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6
Q

What about the corneal epithelium protects the cornea?

A

Constant washing of corneal surfaces

Tears rich in antimicrobial substances

Surface mucus inhibits bacterial colonization

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7
Q

What are the three antimicrobial substances in tears?

A

IgA

Lysozyme

Lactoferrin

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8
Q

What are the three mechanisms by which the uvea are protected?

A

Scelra/Bony orbit

Blood ocular barrier

Anterior chamber immune deviation

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9
Q

What is the blood ocular barrier?

A

Tight junctions between:

Endothelial cells of iris + Retinal blood vessels

Epitheliaum of non-pigmented ciliary epithelium + RPE

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10
Q

What is ACAID?

A

Immune response by which infectious agents that enter into the anterior chamber induce a highly controlled immune response

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11
Q

What are the benefits of the ACAID response?

A

Minimal tissue damage

Very strong response

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12
Q

Why is the uveal tract no protected agains noxious agents in circulation?

A

It has free communicationwith peripheral blood

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13
Q

When an antigen enters the eye how are T cells activated? Why?

A

NO lymphoid tissue in eye

APC’s exit normal aqueous outflow and go to marginal zones in the spleen

T lymphocytes are then activated

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14
Q

What does the blood-eye barrier in the retina consist of?

A

Tight junctions between

RPE cells + Retinal vascular endothelium

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15
Q

What is different about the retina in regards to immune defense compared to the rest of the eye?

A

No real defense at all against infectious agents, radiation, or noxious chemicals through the vitreous

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16
Q

What are the two major pathological processes in which the cornea responds to injury?

A

Adaptive cutaneous metaplasia

– and –

Epithelial/Stromal Necrosis

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17
Q

When does adaptive cutaneous metaplasia normally occur with corneal injury?

A

Mild persistant irritation

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18
Q

What common eyelid disease causes adaptive cutaneous metaplasia in the cornea?

A

Entropion

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19
Q

What is entropion?

A

Inversion of the margin of the eyelid

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20
Q

What is adaptive cutaneous metaplasia a combination of? (5 processes)

A

Keratinization

Epithelial hyperplasia

Epithelial pigmentation

Subepithelial fibrosis

Vascularization

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21
Q

Define: Corneal ulceration

A

Full thickness epithelial loss

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22
Q

How does edema occur with ulcerations of the cornea?

A

Water is absorbed from tear film into the anterior stroma

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23
Q

What is the hallmark of corneal ulceration? How does it manifest?

A

Edema

Opacity

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24
Q

What is the diagnostic technique to diagnosis a corneal ulceration?

A

Fluorescein dye

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25
Q

What is the severe form of corneal ulceration, that occurs once bacteria is present?

A

Neutrophil-induced keratomalacia

aka Melting ulcer

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26
Q

What happens to the eye once there is a melting ulceration? Describe.

A

Desmatocele

Decemet’s membrane bulge anteriorly into defect created

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27
Q

Term: Inflammation of the cornea

A

Keratitis

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28
Q

What happens if the Decemet’s membrane ruptures?

A

Can lead to the loss of anterior chamber fluid

– and –

Iris prolapse

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29
Q

What bacteria can cause suppurative keratomalacia in a horse?

A

Pseusdomonas spp.

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30
Q

What is the process by which suppurative keratomalacia occurs in a horses eye?

A

Proteolytic destruction of the stroma

Caused by digestive enzymes that are released by the neutrophils in the inflammatory exudate

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31
Q

How does a wound in the eye heal if there is only epithlial damage?

A

epithelial sliding

– and –

Mititotic regeneration

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32
Q

If there is full thickness destruction in the cornea what do the epithelial cells first release? What do these cause?

A

IL-1 (cytokine) + PDGF (Growth Factor)

Cause: Necrosis + Apoptosis of Stromal Cells

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33
Q

If there is full thickness destruction in the corneal what do the epithelial cells at the margins of the ulcer release? What do these do?

A

EGF + KGF + HGF

Stimulated epithelial migration + Proliferation

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34
Q

What is the result of the KGF + HGF + EGF release in a corneal ulceration?

A

Flattening + Sliding of viable suprabasilar epithelium

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35
Q

Where do the neutrophils in corneal wound healing come from? What do they do?

A

Come from: Tear film + Limbus

Recruit blood vessels + Fibroblasts

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36
Q

Term: Hypopion

A

Accumulation of Neutrophils + Fibrin

Settles ventrally in the eye

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37
Q

Term: Anterioir Uveitis

A

Inflammation within Iris + Ciliary body

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38
Q

Term: Choroiditis

A

Inflammation only in choroid

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39
Q

Term: Hyalitis

A

Inflammation in vitreous

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40
Q

Term: Panuveitis

A

Inflammation throughout uveal tract

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41
Q

Term: Endopthalmatis

A

Inflammation involving uveal tract + adjacent ocular cavities

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42
Q

Term: Panopthalmatis

A

Inflammation spreads to scleara

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43
Q

What are the three major causes of uveitis?

A

Infectious agents

Immune-mediated reactions

Trauma

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44
Q

What does trauma to the uvea cause?

A

Transient endopthalmatis

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45
Q

What is the most common immune mediated reaction cause by in the Uvea?

A

Lymphoplasmacytic

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46
Q

What virus in a cat can cause hypopyon?

A

Feline infectious peritonitis

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47
Q

What are the eight types of delayed responses to injury in the uvea?

A

Synechiae

Iris bombe

Retinal detachment

Cataracts

Corneal endothelialitis

Preiridal fibrovascualr membrane

Hyphema

Phthisis bulbi

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48
Q

Term: Phthisis bulbi

A

Shrunken disorganized endstage globe

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49
Q

Term: Hyphema

A

hemorrhage within the anterior chamber

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50
Q

Term: Preiridal fibrovascular membrane

A

Layer of granulation tissue of the anterior surface of the eye

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51
Q

What can happen if preiridal fibrovascular membrane migrates across the anterior surface of the lens?

A

Pupillary block occurs

Secondary gluacoma occurs

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52
Q

What can happen if preiridal fibrovascular membrane migrates across the anterior surface of the filtration angle?

A

Anterior synechiae

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53
Q

Term: Corneal endothelialitis

A

Inflitration of neutrophils + lymphocytes into corneal endothelium

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54
Q

How does corneal endothelialitis manifest as?

A

Corneal edema

aka blue eye

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55
Q

What are some causes of corneal endothelialitis?

A

Cats = FIP

Dogs = Canine adenoviral hepatits

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56
Q

Term: Cataracts

A

Lens opacity due to drop in production of aqueous humor

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57
Q

What is an important job of the aqueous humor?

A

Provide nutrients to the lens

58
Q

What is cataracts a sequela to?

A

Uvetitis

59
Q

What is retinal detachment a sequlae to?

A

Uveitis

– and –

Endopthalmititis

60
Q

What are the two mechanisms that retinal detachment can occur?

A

Exudative

– and –

Tractional

61
Q

Describe exudative detachment of the retina

A

increased vascular permeability within the choroid

Leads to:

Effusion of fluid + cells into the subretinal space

62
Q

Describe tractional detachment of the retina?

A

Replacement of fibrinous exudate by fibrous tissue within vitreous

63
Q

Term: Iris bombe

A

Bowing of iris due to increased pressure within posterior chamber in the presence of circumferential synchiae

64
Q

Term: Synechiae

A

Adhesion between the inflammation between the inflammed sticky and either the lens or the cornea

65
Q

What is invovled in a anterior synechiae?

A

cornea

66
Q

What is involved in a posterior synechiae?

A

Lens

67
Q

What is the progression of the adhesions in Synechiae?

A

Fibrinous to fibrous

68
Q

What happens when synechiae becomes extensive?

A

Impairment of aqueous outflow from posterior to anterior chamber

= Pupillary block –> Secondary gluacoma

69
Q

Term: Hematogenous retinal detachment

A

Leakage of liquefied vitreous subretinal space

70
Q

Term: Anopthalmia

A

No detectable development of even primary optic vesicle

Noramlly bilatteral

71
Q

Term: Micropthalmia

A

Minature, disorganized globe in an orbit of normal size

72
Q

What are possible causes of micropthalmia?

A

Exogenous injury to the globe

Utero trauma + Ischemia injury + Infections

73
Q

Term: Cyclopia

A

Failure of division of very primative optic primordium into paired symmetirc optice stalks + vesicles

74
Q

Term: Synopthalmia

A

Cyclopia

with replication of intraocular structures

(ie. retina or lens)

75
Q

What can cause cyclopia in ewes?

A

Veratrum californicum

Day 15 gestation

76
Q

Term: Coloboma

A

Defect in closure of the optic fissure

Retina grows outwardly

77
Q

What is coloboma a hallmark of?

A

Collie eye abnomaly

78
Q

Describe the process of glaucoma.

A

Increase in intraocular fluid pressure

Detrimental to health of optic nerve + retina

79
Q

What are the end results of glaucoma?

A

Decrease in vision

Evenutally blindness

80
Q

What causes primary glaucoma?

A

Ocurring without any known aquired intraocular disease

Developmental errors

81
Q

What is one malformation that can cause primary glaucoma?

A

Goniodysgenesis

82
Q

Term: Goniodysgenesis

A

Imperfect developemnt of trabecular meshwork

83
Q

What are three examples of things that can cause secondary glaucoma?

A

pupillary block

trabecular occulsion

tumors

84
Q

How can a trabecular occulsion occur?

A

Infiltration of neoplastic cells

Peripheral iridiocorneal adhesions

mechanical compression of the base of the iris

85
Q

What are two tumors in dogs that can cause secondary gluacoma?

A

Anterior uveal melanocytoma

– and –

Metastatic lymphoma

86
Q

What are two tumors in cats that cause secondary glaucoma?

A

iris melanoma

– and –

Metastatic lymphoma

87
Q

What are the eight secondary changes with glaucoma?

A

Bupthalmos

Corneal edema

Corneal striae

Atrophy of iris + ciliary processes

Cataracts

Lens luxation

Retinal degeneration

Optic nerve changes

88
Q

Term: Buphthalmos

A

Stretching of the globe secondary to increased intraocular pressure

89
Q

Term: Corneal striae

A

breaks in the Descement’s membrane secondary to corneal scratching

90
Q

Why is there atrophy of the iris and cilliary process with glaucoma?

A

Due to chronic pressure induced ischemia

91
Q

What is the clinical sign that there has been atrophy of the iris?

A

Permanent dilation of the eye

92
Q

Define: Lens luxation

A

Due to stretching of the zonules secondary to ocular enlargement.

Pressure induced degenerative changes in zonules

93
Q

What is the most important secondary change with glaucoma? Why?

A

Retinal degeneration

This is where most glaucoma treatments are targeted

94
Q

What are the contribution factors in glaucoma that cause retinal degeneration?

A

Pressure induced ischemia changes

Interference with ganglion cell nutrition

Direct damage to ganglion cells by elevation local production of excitatory AA’s

95
Q

What causes the optic nerve changes in glaucoma?

A

Posterior displaced of lamina cribosa

– and –

Cupping of optic disc

96
Q

How is a dermoid formed?

A

Failure of the fetal ectoderm to undergo corneal metaplasia

97
Q

What causes superficial stromal sequestration?

A

Injury to corneal epithelium followed by increase in amount of superficial stromal apoptosis

98
Q

In dogs and horses, what is the result of superficial stromal apoptosis?

A

Inability of sliding corneal epithelium to properly adhere to underlying stroma, meaning full epithelial regeneration cannot occur

99
Q

In cats, what is the result of superficial stromal apoptosis?

A

Stromal devitalization is normally greater

Imbition of brown-colored pigemnt into dead stroma

100
Q

What is the pathognomonic feature of corneal sequestrum in a cat?

A

Brown-colored pigment

101
Q

What are the four common systemic mycoses that affect the eye?

A

Blastomycosis

Cryptococcosis

Histoplasmosis

Saprophytic fungi

102
Q

What species of blastomycse?

A

Dermatitidis

103
Q

What species of cryptococcus?

A

neoformans

104
Q

What species of histoplasma?

A

capsulatum

105
Q

What species of saprophytic fungi?

A

Aspergillus + Candida

106
Q

What does balstomyces cause?

A

Dogs

Severe diffues pyogranuloatous endopthalmitis

107
Q

What does cryptooccus neoformans cause in the eye?

A

Lesions mostly in the retina + choroid + optic nerve

Minimal granulomatous response

Cats + Dogs

108
Q

What does histoplasmosis capsulatum cause?

A

Diffuse granulomatous + lymphocytic choroditis with little suppuration

109
Q

When causes lens induced uveitis?

A

Cataracts

110
Q

How do cataracts cause uveitis?

A

lens proteins begin disintegrate + leak through intact lens capsule

= Phacolytic uveitis

111
Q

What is seen in dogs with phacolytic uveitis?

A

Suppurative to pyogranulomatous reaction centered around the lens

112
Q

What animals are uveal neoplasms most common?

A

Dogs and Cats

113
Q

What are the primary tumors of the eye?

A

Melanocytic

– and –

Iridiocillary epithelail tumors

114
Q

What is the most common canine primary uveal tumor?

A

Canine aterior uveal melanocytoma

115
Q

What does anterior uveal melanocytoma arise from?

A

Melanocytes within the stroma of the iris + ciliary body

116
Q

What is the clinical presentation of feline diffuse iris melanoma?

A

Unilateral coalescing hyperpigmentation of iris

Slowly progressing to thickening + secondary glaucoma

117
Q

Where do irdiociliary tumors come from?

A

neuroectoderm of posterior iris or ciliary body

118
Q

What causes feline primary ocular sarcoma?

A

Spindle cell neoplasm

Arises from lens epithelium that espcased through ruptured capsules

119
Q

What is normally the end result of a completely dislocated lens?

A

Cataract

120
Q

Why does a cataract result from the complete dislocation of the lens?

A

inadequate access to aqueous humor

121
Q

What causes a primary lens luxation?

A

Occurs without any known trauma

Developmental error that causes abnormal or insufficent zonules

122
Q

What causes a secondar lens luxation?

A

Blunt trauma

Avulsion of zonules

– or –

Excess stretching of zonules

123
Q

What is thought to be the reason for diabetic cataracts?

A

Excessively high level of glucose within the aqueous humor

124
Q

What is the basic reason for equine keratomycosis for occurring?

A

Opportunistic contamination of corneal wounds by fungi

125
Q

What is the most common fungus to cause equine keratomycosis?

A

Aspergillus

126
Q

What are the the two different things that can occur with equine keratomycosis?

A

Infection of dead superficial stroma by large amount of hyphae with almost no inflammation

– or –

Deep stromal infection that evokes intense suppurative keratomalacia

127
Q

If keratomalacia occurs with equine keratomycosis what can it lead to?

A

Corneal perforation

– and –

Iris prolapse

128
Q

What is Equine recurrent uveitis?

A

Unpredictable episodes of severe uveitis

Increase in frequency

Immunologic reaction against intraocular leptopsiral antigens

129
Q

What is the cause of infectious bovine keratoconjunctivitis?

A

Moraxella bovis

130
Q

What is the vector for moraxella bovis?

A

Flies

– or –

Fomites

131
Q

Why does moraxella bovis cause infectious bovine keratoconjunctivitis?

A

Have capsular pili that are hemolytic

132
Q

How does infectious bovine keratoconjunctivitis present?

A

Shallow corneal ulcers

With severe conjunctival hyperemia

–> Circumferential superfical vascular growth

133
Q

What is the presentation of bovine malignant catarrhal fever-associated uveitis?

A

Peripheral midstromal corneal vascularization

– and –

Anterior Uveitis

134
Q

What breed of dog tends to get canine pannus keratitis?

A

German shephards

135
Q

Where does canine pannus keratitis begin? How does it spread?

A

Starts at lateral limbus

Moves to axial cornea

136
Q

What is uveodermatologic syndrome?

A

Facial dermal depigmentation

– and –

Severe bilateral uveitis

137
Q

What breeds are affected by uveodermatologic syndrome?

A

Akitas

Siberian Huskies

Samoyeds

138
Q

What is the histologic appearance of uveodermatologic syndrom?

A

Destructive granulomatous endophtalmitis

Abundant dispersal of melanin

Consequence of T-lymphocyte mediated destruction of melanin producing cells

139
Q

What virus causes feline herpetic keratitis?

A

Feline herpesvirus 1

140
Q

What occurs with feline herpetic keratiits?

A

Acute to chronic keratitis

Shallow intraepithelial branching tracts of nerocis

= Dendritic ulcers

141
Q

What is the physical characteristic of eosinophilic keratitis?

A

Granular, white proliferative lesion extending inward along corneal surface from medial to lateral limbus

142
Q

What is seen on histologic examimination of eosinophilic keratitis?

A

Nonulcerative superfical stromal infiltration of:

Eosinophils

Plasma cells

Mast cells

Macrophages

Pathology II (20 decks)

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