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VetMed Year 4- Term 1 > w/c 5/5/14 Opthamology > Flashcards

w/c 5/5/14 Opthamology Flashcards

1
Q

What is nuclear sclerosis?

A

Normal aging process affecting the refractive index of the lens. Gives the nucelus of the lens a hazy look

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2
Q

How to differentiate nuclear sclerosis and cataracts

A

Distant direct opthamoscopy. The tapetal reflex would not be observed with cataracts but would be with nuclear sclerosis
LOOK THROUGH OPTHALMASCOPY. DON’T CONFUSE WITH INDIRECT OPTHALMOSCOPY= FUNDUS IMAGE

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3
Q

Lymphoid follicles on the bulbar side of the third eyelid are indicitive of…

A

Young animals, allergies. Accompanied by hyperaemia. Can also occur on the palprebral side.

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4
Q

Conjuncitval pattern of BV’s =

Sequale=

A

Dictomatous branching. Dilation of vessels and seperation of endothelial cells leads to Hyperaemia and Edema (chemosis)

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5
Q

Define chemosis

A

Oedema of the conjunctiva

Conjunctival pattern of BV= dilation of vessels and seperation of endothelial cells leading to hyperaemia and chemosis.

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6
Q

Episcleral pattern is indicitive of

A

No dichotomous branching, larger, meander. Signal intraocular disease (uveitis or glycoma)

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7
Q

What % of tear film is provided by lacrimal gland?

A

30% therefore do not excise cherry eye! Reposition…

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8
Q

4 layers of cornea

A

Epithelium
Stroma
Descemet’s membrane
Endothelium

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9
Q

Cornea epithelium (hydro____, has or had not got BV?)

A

The cornea epithelium is hydrophobic and does not have blood vessels. it does have non-myelinated nerves

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10
Q

Cornea stroma (hydro___) stays _________

A

Cornea stroma is hydrophillic. It stays relatively dehydrated through the action of epithelium and endothelium which actively pumps fluid back into AC

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11
Q

Corneal stroma overhydration is known as

A

Corneal oedema

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12
Q

Name a specific disease for loss of the corneal epithelium

A

Corneal ulcer

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13
Q

Name a specific disease for damage to the endothelium

A

Glacoma, uveitis, lens luxation, primary endothelial degen.

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14
Q

Name a speicif disease for vasculaisation (leakage)

A

Any irritating problem of the cornea (KCS, LPI, ulcers etc)

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15
Q

What structures define the anterior chamber?

A

Corneal endothelium, anterior iris and lens, Iridocorneal angle

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16
Q

Purpose of the aqueous humour that fills the anterior chamber?

A

Establises IOP, feeds posterior cornea and anterior lens.

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17
Q

Route of aqueous humour

A

Comes from cillary body, into POSTERIOR chamber, goes through pupil into AC and exits through the iridocorneal angle/ uvea

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18
Q

Which two diseases affect the anterior chamber?

A

Uveitis (inflamm of uvea) and Glaucoma

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19
Q

How does Uveitis affect IOP ( through its affect of the aqueous humour)

A

Inflamm of the uvea (uveitis) decreases IOP because it increases uveoscleral outflow.
Chronic uveitis can lead to keratic precipitates blocking the flow of aqueous humour and therefore RAISED OCCULAR PRESSURE

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20
Q

Uveitis can lead to

A
  1. Miosis= iris spasm
  2. Endothelial cell seperation leading to leakage of blood components
  3. Posterior synechia
  4. Development of PIFMs
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21
Q

What are posterior synechia

A

Adhesions of iris to the anterior lens. Commonly causes by uveitis

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22
Q

What are PIFMs? Apperance of them

A

Preiridal fibrovascular membranes. Commonly caused by uveitis. Grow over iris and in pale iris visible as rubeosis iridis. May lead to bleeding in eye= hyphema or closure of the ICA = secondary glaucoma

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23
Q

An undilating pupil can be an indication chronic uveitis and is caused by the formation of

A

Posterior synechia (adhesions between iris to anterior lens)

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24
Q

Why do keratitic precipitates, hypopion and hyphema occur in uveitis?

A

Due to endothelial cell seperation leading to leakage of blood components

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25
Q

Define epiphora

Cause of epiphora

A

Excessive tearing. 1) Trigeminal (CN V) irritation or 2) drainage problems (prolpased gland, eye lid abnormality, blockage of nasolacrimal system)

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26
Q

If eyelid mass affects less than ___% wedge resection. if more then consider referral

A

<25% = wedge resection then figure of 8 knot.

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27
Q

Treatment of Spastic entropion

A

When eye is closed tightly (blepharospasm) can lead to spastic entropion. Apply 1 drop of proxymetacaine (topical anaesthetic) if entropion persistas needs surgical correction if disappears investigate source of opthalmic pain

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28
Q

Difference between Strabismus and Nystagmus

A

Strabismus: Deviation in the position of the globe (congenital, neurologic or extraocular muscle abnormality)

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29
Q

Which nerves supply the extraocular muscles (and subsequent damage produces specific strabismus)

A

Strabismus = deviation of the globe. Most muscles innervated by oculomotor (CN III)
Abducens: Lateral rectus (ALR)
Trochlear: Superior Oblique (TSO)
Nystagmus= involuntary oscillatory movement of the eyes

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30
Q

Which breed of cats are predisposed to congenital strabismus?

A

Siamese cats.

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31
Q

What is a coloboma?

A

Congenital absence of tissue within the eye or adnexa. Normally lahteral part of eyelid in cat.
Can have eyelid coloboma

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32
Q

Define ankyloblepharon

A

Aklyoblepharon is normally in kittens/puppies up to 10-14 days old.

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33
Q

Pathogeneisis and treatment of Opthalmia neonatorum

A

Development of a purulent conjunctivitis prior to eyelid opening. Swelling of the fused lids.
Eyelids need to be surgically opened early to avoid corneal damange. Broad spec topical antiobiotics.

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34
Q

Inflammation of the eyelids is known as

A

Blephritis

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35
Q

Define symblepharon

A

Seqalae to conjunctivitis which conjunctival adhesions form. Common result of feline herpes virus-1.

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36
Q

Which virus is associated with corneal oedema in dogs?

A

Canine adenovirus is associated with corneal oedema, (so is anterior uvetitis) forms immune-complexes on corneal epithelium preventing pumps removing fluid

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37
Q

Breed predisposition for plasmoma

A

Plasmoma - inherited in GERMAN SHEPHERD DOGS.
Thickened irregular boarder. IM disease therefore ciclosporin.
Related condition to Chronic superficial keratitis/ pannus. but PLASMOMA only AFFECTS THIRD EYELID

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38
Q

Aeitiology and treatment of Episcleritis

A

Episcleritis is an immune-mediated disease of the episclera. Responds to corticosteroids e.g. Azothiaprine.

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39
Q

Left eye is known as…

A 
Oculus sinister (the left eye)
OD= right eye
OU = Both eyes.
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40
Q

Young golden retriever with bilateral, non painful exophalmos is likely to have

A

Extraocular polymyositis. Systemic corticosteriods +- Azothiaprine (immunosuppressive)

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41
Q

What is the probably cause of corneal oedema in a Daschund

A

Inherited endothelial dystrophy in boston terriers, chihauhuas, dauchunds, english springer spaniels

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42
Q

Aetiology of sequestrum

A

Major cause of black/brown corneal lesions in cats. Consists of necrotic corneal stroma and often surrounded by a ring of inflammatory cells. Can be unilat or bilat. Often associated with herpes

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43
Q

Sequestrum in cats often associated with what virus

A

Herpes virus.

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44
Q

Define Lagophtalmos

A

Inability to close the eye completely.

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45
Q

Where do the first lesions of CSK appear?

A

CSK is Chronic superficial keratitis and is an immune mediated disease aka ‘Pannas’ aka lymphocy..plsmocytic..
It first appears in the VENTROLATERAL quadrant

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46
Q

Exposure to ___ is known to be a predisposing factor for CSK /Pannus/LPI

A

UV light.

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47
Q

What does the third eyelid normally have a roughened appearance?

A

Due to the lymphoid tissue

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48
Q

What are Habbs Striae

A

Stretch marks ‘breaks in Descemet’s membrane

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49
Q

Aqueous flare is pathopneumonic for

A

Uveitis

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50
Q

Treatment for Glucoma

A

Glucoma (40-60 mmHg = clinc signs of bupthalmia
Miotics (constrict pupil) e.g. Pilocarpine
Mannitol
Beta-blockers
Carbonic anhydrase inhibitors

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51
Q

Normal Schirmer tear test for dogs

A

> 15mm/min
TSS-1 = NO ANAESTHIC (dogs have less corneal nerves)
TSS-2 = WITH ANAESTHETIC

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52
Q

When would you use blue light?

A 
Blue light: Fluorescein
Green light (aka red free): Differentiate blood from pigment
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53
Q

Type of image with indirect opthalmoscopy

A

Used for wide field of view of fundus
Inverted virtual Left to Right image.
Don’t confuse with DDO (used for tapetal reflex/ cataracts vs nuc sclerosis)

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54
Q

Where do you place STT strip?

A

Use STT-1 (no anaesthetic) LATERALLY (doesn’t interfer with third eyelid)
BEFORE USE LIGHT EXAMINATION
>15mm/min = good but if ulcer could be pain?

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55
Q

Persistant Papillary Membranes

A

Remnants of normal prenatal vascular network.
Not uncommon in dogs
Presence of pigmented strands from one side of iris to the other
ARISE FROM THE IRIS COLLARETE
Can cause CORNEAL and LENS opacity

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56
Q

Close direct ophthalmology

A

<2cm from patient!
Look for optic disk. Make big picture.
All vessels lead to optic disk. Divide into 1/4s

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57
Q

Jones test

A

Use Fluorescein staining but do not wash.
Check nasolacrimal duct patency.
Should flow in <4minutes
Examine with BLUE light

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58
Q

Normal IOP range

A

12-22 (24)

Glucoma vs Uveitis

59
Q

Ectopic cilia

A

Associated with meibioum glands but not through openings (c.f. Distichiasis)
Bulbar surface of eye - nearly always central upper eyelid
Normally one hair, one location.
Normally <1.5 years.
Also affects horses

60
Q

Distichiasis

A

Hairs are normally multiple (upper and lower eyelids of one or both eyes)
Sprout through meibioum gland openings

61
Q

Eosinophillic keratitis- what species?

A

Mainly cats but also horses and rabbits.

Red/pink cellular infiltrate

62
Q

Canine Lymphocytic Plasmacytic Infiltrate commonly affects _____ area first

A

Dorsolateral conjuncitva affected first

Cellular infiltrate and vasculisation

63
Q

Diagnosis of Canine Lymphocytic Plasmacytic Infiltrate

A

Cytology.

Proxymetacaine (topical anaesthetic), decrease blink, increase dryness= cytobrush and diffquick

64
Q

Treatment of LPI

A

Dogs: Cyclosporin. Dogs in temperate climates respond well. Sunny climates do not
Cats (EK): Topical steroid (dexamethasone)
START WITH 4-6 x daily
Taper very very slowly!

65
Q

Treatment of KCS

A

Topical ciclosporin.

PERSERVATIVE FREE viscous tears

66
Q

Lipid infiltrate; how to differentiate primary and secondary form

A

DEGREE OF VASCULARISATION
Primary: (dystrophy) no vasculisation. King Charles Spaniels, Huskies
Secondary: Degeneration, HAS vasculisation. Associated with chronic corneal problems. Hypothyroidism?

67
Q

How to differentiate lipid deposits and calcium deposits?

A

Lipid deposits: Primary or secondary (vascularisation) but both ARE REFLECTIVE
Calcium deposits: NON-reflective crystals, reticulated pattern. Vascularisation.

68
Q

Pathogenesis of Corneal Abscess and likely progression

A

Accumulation of WBC. Enzymes can lead to rapid collagen melting.
Not a pocket of fluid (cannot be drained)

69
Q

Pathogenesis of Sequestra

A

Prodominately cats.
Normally affects medial cornea (most vulnerable part)
Spontaneous but commonly associated with chronic irritation

70
Q

Where is the limbus

A

Where the cornea meets the white of the eye.

71
Q

Where would you find the Lacrimal gland?

A

Produces 30% of aqueous portion of tear film.
Found in the third eyelid (along with T shaped cartilage)
Can become inflammed ‘Cherry eye’

72
Q

What makes up the a) Anterior uvea b) Posterior uvea

A

Anterior uvea: Iris/Cillary body

Posterior uvea: Choroid

73
Q

Pathogenesis of secondary glucoma resulting from anterior uveitis

A

Anterior uveitis: Can development of PIFMs (Preiridal fibrovascular membranes) which grow over iris and pale it = rubeosis iridis which can lead to hyphema but also block the ICA therefore rasing intraoccular pressure (normal is 12-22/24)

74
Q

Panuveitis

A

Inflammation of the anterior part AND POSTERIOR part of the uvea (posterior uvea= choroid)
Can lead to reinal detachment.
Retina overlies choroid (i.e. retina is most internal)

75
Q

Meibioium glands produce

A

Lipid

Reduces evaporation of tears

76
Q

Entropion in 20 day old puppy. Treatment?

A

Entropion is INVERTION of eyelid.

Tacking sutures after eyelid opening - too young to undergo surgery

77
Q

Treatment of entropion

A

Check if spastic entropion - apply 1 drop proxymetacaine. to check if spastic entropion (i.e. pain)
If entropion = surgery

78
Q

Cause of entropion

A

Brachycephalic breeds skull deformity.

Or cats: Eldery cats= skin laxity or loss of retrobulbar fat.

79
Q

Euryblepharon

A

(= macroblepharon
Enlargement of eyelid i.e. more of the sclera is visible than it should be
e.g. blood hounds

80
Q

How to look for hypopion

A

= Accumulation of WBC in anterior chamber can lead to blindness.
Push down lower eyelid (gently!) as POOLS at bottom

81
Q

Appearance of posterior synechia

A

Adhesion of iris to cornea.

Will appear as a distorted pupil (i.e. not round/ smooth )

82
Q

Pathogenesis of Lens Induced Uveitis

A

Treatment of cataracts in dogs is photoemulsification and implantation of news lens. leaking lens can lead to a secondary glucoma by blocking the ICA.
Regular monitoring and occasional use of steroids and

83
Q

3 infectious agents that are reported to affect uvea

A 
1/ Toxoplasmosis
2/ Leishmania
3/ Cryptococcus 
4/ FelV/FIV 
HYPERTENSION????
84
Q

How can uveitis cause cataracts

A

Cataracts can cause uveitis (phacolytic - intact capsule. phacoclastic- rupture of lens capsule)
Uveitis sequale can be cataracts due to poor nourishment of the lens and altered aqueous humour

85
Q

How does cataract colour differ between direct illumination and retroillumination

A

Direct illumination: (Distant direct opthal) = white

Retroillumination= dark

86
Q

Congenital cataracts are always

Heritability?

A

Nuclear (in centre)

Congenital but RARELY INHERITED

87
Q

Pathogenesis of Diabetic cataracts

A 
Glucose in anterior chamber
Sorbitol 
Water
Something happens..
Look it up
88
Q

What type of cataracts form during progressive retinal atrophy

A

Secondary to retinal degeneration
• Retina when degenerates releases toxins (glutamate)
that lead to cataracts
PRA: Night blindness progresses to day blindness
Often starts middle aged
No treatment, not painful

89
Q

Senile cataracts tend to be

A

Wedge shaped. Generally affect the cortex

90
Q

Presentation of PRA

A

Hyperreflective tapetum due to thinning of retina
Thinning of retinal vessels
Late stage: Cataracts

91
Q

Most common neoplasia of optic nerve

A

Meningioma
Infectious diseases that affect optic nerve:
distemper, ehrilichia, cryptococcus

92
Q

Collie Eye Abnormalty

A

INHERITED
Combination of 2 diseases
Choroidal hypoplasia (genetic test avaliable)
Optic nerve head coloboma

93
Q

SARDS test

A

Sudden Aquired Retinal Degeneration Syndrome
Test: ERG (electroretingraphy)
plr may or may not be present

94
Q

High doses of which antibiotic can lead to retinal toxicity in cats?

A

Enrofloxacin

Can also cause neurological clinical signs

95
Q

Bupthalmia vs Exophtalmos

A

Bupthalmia: enlargement of eye due to increased IOP
Exophtalmos: anterior displacement of eye

96
Q

What other changes would you expect with Bupthalmia

A

Enlargement of eye due to increased IOP. (Norm is 12-22mmHg)
Increased IOP i.e. glucoma leads to secondary opthalmic changes such as episcleral congestion, corneal oedema, Habb’s striae (breaks in Descements membrane)

97
Q

Which ophthalmic condition are terriers especially predisposed to

A

Primary lens luxation which can lead to secondary glaucoma.

98
Q

Lantanoprost

A

Prostaglandin analogue that increases outflow of aqueous humour therefore decreases IOP.
Lantanoprost also causes miosis therefore can help in cases of lens luxation (miosis prevents moving anteriorly)
Doens’t work in cats, works in horse

99
Q

Retina has ___ layers

A

1 epithelial layer
9 neural layers (with rods, cones and ganglion cells)

total of 10 layers

ganglion axons make up optic nerve

100
Q

Two types of gluacoma, which is most common in dogs?

A

Open angle and Closed angle (rapid onset, most common in dogs)

101
Q

How do signs of glucoma differ between a) moderate->high IOP b) high to very high IOP

A

a) Moderate-> High: Mid dilated non-responsive pupils, episcleral congestion, negative menace
b) High to very high IOP: CORNEAL OEDEMA, Habbs straie (breaks in Descemet’s membrane)

102
Q

Aphakic Crescent =

A

A crescent shaped gap that forms between pupil and lens

Secondary to tears of the zonules and lens movement away from it.

103
Q

Three typical signs of retrobulbar disease

A

Globe displacement, TE protrusion and

change in facial symmetry

104
Q

What is an IOP curve

A

Careful serial measurement of IOP q3hr

over a 30hr period (approximately)

105
Q

Two causes of microphthalmia

A
  1. Usually small eye from birth (normally bilateral)
  2. Destruction of the cillary body (cyclodestruction)
    Sequalae to inflammation, Pthiasis Bulbi (severe uveitis)
106
Q

Infectious diseases that can cause secondary glucoma in cats (4)

A

Mostly associated with uveitis (normally decrease IOP but if chronic can lead to increase IOP and glaucoma)
FIV, FeLV, FIV and Toxoplasma.

107
Q

In which cat species is there thought to be a primary glaucoma condition?

A

Burmease.

Also secondary forms exist: FIV, FeLV, FIP, Toxoplasma.

108
Q

Relevance of primary over secondary glaucoma with respect to longer term prognosis

A

Primary: Second eye WILL be affected. Guarenteed.
Secondary: Might be less of a worry; MONITOR

109
Q

Can you breed from animals with glaucoma?

A

Burmease: Primary Glucoma is inherited!
Primary: NO as dysgenesis of ICA is inherited
Secondary: CAN BREED (EXCEPT LENS LUXATION=Terriers!)

110
Q

Treatment of Glaucoma, 3 types

A
  1. Beta-blockers e.g. timolol, reduce production of aqueous
  2. Carbonic Anhydrase Inhibitors
  3. Prostaglandin analogue (Lantanoprost)- Increases uveoscleral outflow.
111
Q

How does Timolol work?

A

Tx for Glaucoma.

Timolol is a beta blocker that works but reducing production of aqueous humour.

112
Q

How does Dorzolamide work?

A

Tx for Glaucoma.
Dorzolamide is a Carbonic Anhydrase inhibitor which works but reducing the production of aqueous humour
i.e. similar to the beta blocker Timolol
Works well with beta blocker.

113
Q

Carbonic Anhydrase is the treatment of choice for ___ and ___

A

cats and horses.
e.g. Dorzolamide
Works by reducing the production of aqueous humour

114
Q

Latanoprost side effects

A

Prostaglandin analogue that works by increasing outflow.
Doesn’t work in cats, works in horses.
MEDIATOR OF INFLAMMATION!! Can cause uveitis
Strongest (c.f. beta blockers, carbonic anhydrase inhibitors)

115
Q

Phacodonesis

A

tremulousness or vibration of the lens with eye movement
Often due to lens subluxation.
Breaks in zonular fibres.
Phaco= lens
c.f: Iridodonesis : Vibration of iris with movement

116
Q

What clinical signs can be an early sign of subluxation

A

Phacodonesis (lens vibration)
Iridodonesis (iris vibration)
Anterior presentation of viterous

117
Q

Sequalae of posterior luxation

A

Cataract formation
Lens induced uveitis
Lens adhesion to retina

118
Q

Sequalae to anterior luxation

A

Pupil block glaucoma

Also damages cornea leading to corneal oedema.

119
Q

Endolaser cyclophotocoagulation

A

Cyclo= referring to cillary body
Want to remove part of it to decrease aqueous humour production.
leave 30% intact to avoid phtsis bulbi

120
Q

Difference between Basal cells and Wing cells of cornea

A

Basal cells: Transient amplyfying cells, capable of mitosis. Stemp cells at limbus
Wing cells: No longer mitotic 2 to 4 layers
Final most exterior layer is the squamous non-keratinised epithelium

121
Q

Wound healing of Cornea process

A

First sliding post abrasion (doesn’t reach basal lamina)
THEN basal cell mitosis, movement upwards. Takes 1 week/cycle.
THEN Centripetal movement -from limbus to centre; affects every layer.
WOUND HEALING DEPENDS ON EXISTANCE OF BASAL LAMINA

122
Q

Significance of Centripetal movement in corneal wound healing

A 
First sliding (doesn't affect basal lamina) then upwards movement from basal cells mitosis. THEN Centripetal movement from limbus to centre. 
Clin Signif: Pigment proliferation associated with irritation  can migrate centrally over pupil.
123
Q

How can vascularisation be an indicator of chronicity

A

Lag time of 2 to 4 days to bud.

Then 1mm/day approx

124
Q

During corneal wound healing what is the first GAG to form

A

Change of concentration of GAGs.

First GAG to form is HA. Then HA decreases as other glycoproteins increase in concentration

125
Q

Shape of the endothelium / wound healing

A

Exagonal in a chicken wire pattern.
Intracellular Na+K+ATPase pumps to keep corneal stroma relatively dehydrated
Endothelial cells: very sensitive cells with poor ability to regenerate.

126
Q

Medical treatment for corneal ulcer

A 
Protection from self harm=COLLAR
Antibiotic cover= protection
Atropine for comfort= mydriasis 
Ciclosporin will NOT intefer with healing 
NO STEROIDS/NSAIDS
127
Q

Tarsorrhaphy

A

Horizonal mattress suture through eyelids .
Use stents to protect eyelid.
Alternatively Nicititating membrane flap but not recommended over a bandage lens/ tarsorrhaphy.

128
Q

Medical Tx for Corneal Melting

A

Serum eyedrops - antiproteases

Frequent application every 30 minutes

129
Q

How long until need to re-examine corneal ulcer

A

3-4 days

Healing is AIDED by vascular growth.

130
Q

Desmatocele

A

Right before perforation occurs. Partial bulging of Decemet’s membrane. Does not uptake fluorescein (surrounding edematous stroma does)
CLEAR CENTRE as no stroma.
SURGICAL EMERGENCY

131
Q

Pathogenesis of KCS causing perforation of cornea

A

Diseased cornea. Irritant still present, increased thick mucoid discharge leads to a change in the bacterial flora, inflamm cells on surface leading to Collagenolysis.

132
Q

How does SURGICAL treatment of KCS vary depending on where lesion is

A

a) Central lesions: CLCT: Corneolimboconjunctival transposition
Clears over time
b) Peripheral lesions: Conjunctival pedicle graft . Slightly faster.
Conjunctival pedicle doesn’t clear much over time but as peropheral doesn’t matter.

133
Q

Medical treatment of KCS

A

Ciclosporin.
Does not interefere with corneal healing.
Viscous free tears.
Topical antibiotic e.g. Chloramphenicol (broad spec, good penetration)

134
Q

Spontaneous chronic corneal epithelial deficits:

A 
CATS/DOGS
Under running of fluroe
scein dye= Pulsed saline test. 
Loose epithelial edges 
Tx: Keratectomy (cats beware SEQUESTRUM!)
No superficial grid scraping in cats
135
Q

Corneal thickness

A

0.5mm

136
Q

FHV-1 lives in..

A

Trigeminal ganglion and corneal tissue.
Usually infected in kitten-hood.
Associated with symblepharon in kittens.
Corneal ulcerative disease can be severe.
Recrudencent disease during periods of stress.
Tx: Interferon (decreased cytopathic effects) and L-Lysine (reduced replication)

137
Q

Feline Acute Bullous Keratopathy

A

Acute development of corneal oedema.
Risk of melting/ perforation is very high.
REFER

138
Q

Tx for Facial n. paralysis

A

Loss of blink.
Treat underlying cause (FHV-1, Otitis media, ear canal neoplasia etc) = myrinectomy to investigate.
treat with Tarsorrhaphy for 2-3 months (horizonal mattress suture)

139
Q

Most common type of neoplasia of the iris. How does it differ in cats and dogs

A

Melanocytic neoplasia.
Dogs: normally localised/ diffuse. BENIGN. Melanocytoma Cats: normally diffuse melanoma (very slowly malignant)
Swinging light test; still SOME constriction.

140
Q

What is the result of a lesion affecting the

left optic tract?

A

Loss of vision on right .

141
Q

Marcus Gunn sign

How can you differentiate this from unilateral glaucoma?

A

Prechiasmal (i.e. before optic chiasm, closer to eye), unilateral afferent lesion (ipsilaterally affected if prechiasmal!)
Can differentiate from unilateral glaucoma as with glaucoma affected eye will not dilate even with indirect PLR (due to increased IOP damaging iris)

142
Q

Menace response for prechiasmal lesion OS

A

If PRECHIASMAL lesion would not have a menace response is UNILATERAL eye.
I.e. lesion OS, no menace OS

143
Q

PLR for prechiasmal lesion

A

No direct PLR response.
Indirect affected to unaffected= no response
Will have PLR indirect from unaffected to affected.

VetMed Year 4- Term 1 (12 decks)

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