Ophth - anterior segment conditions

Question 1

What is the uvea made up of?

Answer 1

The iris, ciliary body and choroid

Question 2

What are the functions of the choroid?

Answer 2

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

Question 3

What does the choroid contain?

Answer 3

Tapetum lucidum

Question 4

What are the different sections of the uvea called?

Answer 4

Anterior and posterior chambers

Question 5

Where is aqueous humour produced?

Answer 5

Ciliary body

Question 6

Where does the aqueous humour drain out of?

Answer 6

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

Question 7

Where does the aqueous humour fill?

Answer 7

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

Question 8

What is uveitis?

Answer 8

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

Question 9

What are the main clinical signs of uveitis?

Answer 9

Blepharospasm
Epiphora
Lacrimation
Hyperaemia
Corneal oedema

Question 10

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

Answer 10

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

Question 11

What is rubeosis iridis?

Answer 11

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

Question 12

What is aqueous flare?

Answer 12

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

Question 13

What effect does aqueous flare cause?

Answer 13

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

Question 14

What does fibrin look like in uveitis?

Answer 14

Clots into wisps/threads in the anterior chamber

Question 15

What are keratic precipitates?

Answer 15

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

Question 16

What is hypopyon?

Answer 16

Purulent exudate which clumps and settles in the ventral anterior chamber

Question 17

What is a secondary effect of hypopyon?

Answer 17

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

Question 18

What is hyphaema?

Answer 18

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

Question 19

What can cause hyphaema?

Answer 19

Uveitis
New blood vessels being more friable
Trauma
Glaucoma
Coagulopathies
Tumour

Question 20

What do iris lymphoid follicles look like?

Answer 20

Black marks around the periphery of the pupil

Question 21

What are iris lymphoid follicles?

Answer 21

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

Question 22

What are the clinical signs of chronic uveitis?

Answer 22

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

Question 23

What are synechia?

Answer 23

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

Question 24

What are secondary effects of synechia?

Answer 24

Risk of blockage of the drainage angle and secondary glaucoma

Question 25

What is iris bombe?

Answer 25

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

Question 26

What causes lens luxation?

Answer 26

Inflammation of eye weakens and breaks down zonular attachments

Question 27

What is Phthisis bulbi?

Answer 27

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

Question 28

What can cause uveitis?

Answer 28

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

Question 29

What tests should you do in a uveitis case?

Answer 29

Haem, biochem Urinalysis Thoracic radiography Abdominal ultrasound

Question 30

What is lens induced uveitis?

Answer 30

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

Question 31

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

Answer 31

Phacoclastic (blasts the antigens all at once)

Question 32

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

Answer 32

Phacolytic

Question 33

When does a phacolytic lens induced uveitis occur?

Answer 33

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

Question 34

How do you treat uveitis?

Answer 34

Remove primary cause Control inflammation Prevent complications Relieve pain - analgesia

Question 35

What can you give to relive pain from uveitis?

Answer 35

NSAIDs Atropine Opioids Topical steroids - pred, dexamethasone

Question 36

How does atropine reduce pain from uveitis?

Answer 36

Relief from painful ciliary muscle spasm Mydriasis - reduces synechiae

Question 37

What are the functions of the lens?

Answer 37

Focuses light onto the retina Accommodation - near and far

Question 38

What is lenticular nuclear sclerosis?

Answer 38

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

Question 39

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

Answer 39

Hyaloid artery This regresses once aqueous humour is being produced

Question 40

What makes the lens transparent?

Answer 40

Soluble protein No vessels Few organelles Fibres regularly arranged

Question 41

What shape do lens fibres make?

Answer 41

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

Question 42

What are the 4 main classifications of cateracts?

Answer 42

Incipient Immature Mature Hypermature

Question 43

What is incipient cateracts?

Answer 43

When less than 15% of the lens is affected

Question 44

What is immature cateracts?

Answer 44

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

Question 45

What is mature cateracts?

Answer 45

No tapetal reflex

Question 46

What is hypermature cateracts?

Answer 46

Shrinking

Question 47

What can cause cateracts?

Answer 47

Inherited Diabetes mellitus Senile/old age Trauma Lens luxation Uveitis

Question 48

What causes diabetic cateracts?

Answer 48

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

Question 49

How do you treat cateracts?

Answer 49

Phacoemulsification No medical treatment - topical NSAIDs

Question 50

What is lens luxation/subluxation?

Answer 50

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

Question 51

What are the clinical signs of lens luxation?

Answer 51

Aphakic crescent Vitreous prolapse Anterior or posterior Cataract

Question 52

What is an aphakic crescent?

Answer 52

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

Question 53

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

Answer 53

Crescent between the lens and the pupil

Question 54

What can cause lens luxation?

Answer 54

Inherited defect Trauma Uveitis Secondary to glaucoma

Question 55

What is vitreous prolapse?

Answer 55

Strings of jelly in the aqueous humour

Question 56

How can you treat lens luxation?

Answer 56

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

Question 57

What is couching?

Answer 57

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