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CVSOH BVSc4 > Ophth - anterior segment conditions > Flashcards

Ophth - anterior segment conditions Flashcards

1
Q

What is the uvea made up of?

A

The iris, ciliary body and choroid

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2
Q

What are the functions of the choroid?

A

Supplies nutrients to the retina
Site of blood aqueous barrier and blood retinal barrier (tight junctions which maintain the immune privileged site)

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3
Q

What does the choroid contain?

A

Tapetum lucidum

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4
Q

What are the different sections of the uvea called?

A

Anterior and posterior chambers

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5
Q

Where is aqueous humour produced?

A

Ciliary body

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6
Q

Where does the aqueous humour drain out of?

A

The iridocorneal angle - through the pectinate ligaments into the trabecular meshwork of the ciliary bodyq

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7
Q

Where does the aqueous humour fill?

A

The posterior chamber, then flows out of the pupil into the anterior chamber

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8
Q

What is uveitis?

A

Inflammation of the uvea
Breakdown of the blood aqueous barrier and the blood retinal barrier

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9
Q

What are the main clinical signs of uveitis?

A

Blepharospasm
Epiphora
Lacrimation
Hyperaemia
Corneal oedema

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10
Q

What are the pathognomic signs of uveitis (if you see these you can diagnose uveitis)?

A

Keratic precipitates
Aqueous flare
Fibrin
Hyphaemia
Hypopyon
Rubeosis iridis
Swollen iris
Aqueous flare

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11
Q

What is rubeosis iridis?

A

Hyperaemia of the iris - neovascularisation and vasodilation
The iris appears reddened
Difficult to see in animals with a dark brown iris

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12
Q

What is aqueous flare?

A

Protein or cells in the anterior chamber that have leaked through the blood aqueous barrier

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13
Q

What effect does aqueous flare cause?

A

Tyndall effect - scattering of light by particles in a fine suspension causing a sparkly misty effect

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14
Q

What does fibrin look like in uveitis?

A

Clots into wisps/threads in the anterior chamber

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15
Q

What are keratic precipitates?

A

Accumulations of WBCs which clump and attach themselves to the cornea causing oedema and cloudiness (endothelium cant pump water out)

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16
Q

What is hypopyon?

A

Purulent exudate which clumps and settles in the ventral anterior chamber

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17
Q

What is a secondary effect of hypopyon?

A

This purulent debris can block the drainage angle and cause secondary glaucoma

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18
Q

What is hyphaema?

A

Blood in the anterior chamber - vessels leak RBCs
Can be free floating or a clot

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19
Q

What can cause hyphaema?

A

Uveitis
New blood vessels being more friable
Trauma
Glaucoma
Coagulopathies
Tumour

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20
Q

What do iris lymphoid follicles look like?

A

Black marks around the periphery of the pupil

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21
Q

What are iris lymphoid follicles?

A

They develop in response to inflammation
Histologically they are B and T cells that have arrived due to antigenic stimulation

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22
Q

What are the clinical signs of chronic uveitis?

A

Synechia
Hyperpigmentation of the iris
Iris bombe
Glaucoma
Lens luxation
Phthisis bulbi

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23
Q

What are synechia?

A

Adhesions between the iris and adjacent tissues - can be in the anterior or posterior segments

24
Q

What are secondary effects of synechia?

A

Risk of blockage of the drainage angle and secondary glaucoma

25
Q

What is iris bombe?

A

When there are synechia attaching the iris to the lens the whole way round

26
Q

What causes lens luxation?

A

Inflammation of eye weakens and breaks down zonular attachments

27
Q

What is Phthisis bulbi?

A

Chronic low pressure in eye causing globe to shrink and eye to be non-functional

28
Q

What can cause uveitis?

A

Trauma
Anaemia
Hypertension
FeLV/FIV
Septicaemia
Endotoxaemia
Diabetes mellitus
Immune mediated

29
Q

What tests should you do in a uveitis case?

A

Haem, biochem
Urinalysis
Thoracic radiography
Abdominal ultrasound

30
Q

What is lens induced uveitis?

A

Immune mediated
Lens is formed very early - in the first month of gestation
Therefore its lens proteins are hidden from the immune system
Any escape of lens protein is highly antigenic to the eye
This causes profound intraocular inflammation and uveitis

31
Q

What is the name for a sudden, acute lens induced uveitis?

A

Phacoclastic (blasts the antigens all at once)

32
Q

What is the name for a chronic, leaky lens induced uveitis?

A

Phacolytic

33
Q

When does a phacolytic lens induced uveitis occur?

A

When a cateract becomes hypermature over many years of development, the solid opaque lens protein can start to liquefy into smaller molecules that can then cross the intact lens capsule causing uveitis

34
Q

How do you treat uveitis?

A

Remove primary cause
Control inflammation
Prevent complications
Relieve pain - analgesia

35
Q

What can you give to relive pain from uveitis?

A

NSAIDs
Atropine
Opioids
Topical steroids - pred, dexamethasone

36
Q

How does atropine reduce pain from uveitis?

A

Relief from painful ciliary muscle spasm
Mydriasis - reduces synechiae

37
Q

What are the functions of the lens?

A

Focuses light onto the retina
Accommodation - near and far

38
Q

What is lenticular nuclear sclerosis?

A

Produce lens fibres very slowly throughout life
Therefore lens enlarges very slowly throughout life which causes cloudiness in the nucleus as it gets squashed by new layers

39
Q

What provides nutrition to the lens as it forms in the foetus?

A

Hyaloid artery
This regresses once aqueous humour is being produced

40
Q

What makes the lens transparent?

A

Soluble protein
No vessels
Few organelles
Fibres regularly arranged

41
Q

What shape do lens fibres make?

A

Fibres run from pole to pole and meet at suture lines at front and back of eye - inverted Y shape

42
Q

What are the 4 main classifications of cateracts?

A

Incipient
Immature
Mature
Hypermature

43
Q

What is incipient cateracts?

A

When less than 15% of the lens is affected

44
Q

What is immature cateracts?

A

When there is still a light reflex - can still see the tapetum

45
Q

What is mature cateracts?

A

No tapetal reflex

46
Q

What is hypermature cateracts?

A

Shrinking

47
Q

What can cause cateracts?

A

Inherited
Diabetes mellitus
Senile/old age
Trauma
Lens luxation
Uveitis

48
Q

What causes diabetic cateracts?

A

Sorbitol produced from hyperglycaemia being broken down in the aldose reductase pathway
Sorbitol draws water in through the capsule pushing apart the lens fibres

49
Q

How do you treat cateracts?

A

Phacoemulsification
No medical treatment - topical NSAIDs

50
Q

What is lens luxation/subluxation?

A

When the zonules breakdown and the lens loosens
If they are all broken then the lens is freely floating

51
Q

What are the clinical signs of lens luxation?

A

Aphakic crescent
Vitreous prolapse
Anterior or posterior
Cataract

52
Q

What is an aphakic crescent?

A

The lens is in front of the pupil so you can see a clear area in pupil around the lens - shouldnt be able to see the edges of the lens

53
Q

What is a sign that the lens is posterior to the pupil?

A

Crescent between the lens and the pupil

54
Q

What can cause lens luxation?

A

Inherited defect
Trauma
Uveitis
Secondary to glaucoma

55
Q

What is vitreous prolapse?

A

Strings of jelly in the aqueous humour

56
Q

How can you treat lens luxation?

A

Intracapsular lens extraction - remove whole lens
Phacoemulsification (if subluxation)
Couching - medical

57
Q

What is couching?

A

Treatment for lens luxation - lens massaged into posterior segment of eye then construct pupil

CVSOH BVSc4 (86 decks)

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