The Opaque Eye

Question 1

What does white/ yellow deposits in the eye suggest?

Answer 1

Lipid Calcium, Abscess/ Infiltrate, Scar/ Fibrosis

Question 2

What does Blue in they eye suggest?

Answer 2

Corneal Ulcer, Vascularisation (leaky vessels), Intraocular disease e.g. Uveitis, Glaucoma

Question 3

What does abnormal brown/ black pigment in the eye suggest? (5)

Answer 3

Mechanical irritation
Sequestrum (common in cats- piece of cornea died off and taken on a brown discoloration)
Pigmentary Keratitis
Melanoma
Foreign Body

Question 4

Clotted Aqueous humour and brown spots in the iris are a tell tale sign of what?

Answer 4

Perforation

Question 5

Why is the healthy cornea transparent?

Answer 5

no blood vessels, myelinated nerves or pigment

Question 6

What four diagnostic tests can we use to test for Corneal Disease?

Answer 6

1. Schirmer Tear Test
2. Fluorescein for ulceration
3. Seidel Test for perforations
4. Cytology- for bacteria

Question 7

What is healing process in the epithelium layer of the cornea?
How long does it take?

Answer 7

Enlargement and sliding of epithelial cells occurs in the first 1-2 hours
Then they undergo Mitosis to heal- this takes 1-2 weeks for completion

Question 8

If the Corneal stroma becomes damaged- how long does it take to fully heal and why?

Answer 8

Can take weeks to months to fully heal as it needs to form new collagen fibres and lamellae

Question 9

How long does it take the corneal endothelium to heal and why?

Answer 9

weeks- months > endothelial cells have a limited capacity for Mitosis so instead they enlarge in size, reduce in number and lose their hexagonal appearance

Question 10

Blood vessels and Vascularisation heal at a rate of …

Answer 10

0.5mm a day

Question 11

What is SCCED?

Answer 11

Spontaneous Chromic Corneal Epithelial Defect- on top of the stroma, the HAZ layer stops the epithelium from sticking down onto the stroma hence why it appears as if layers of the cornea are peeling

Question 12

What is Descemetocele?

Answer 12

surrounding corneal oedema around an ulcer

Question 13

Can we use Fluorescein to diagnose a Descemetocele?

Answer 13

Fluorescein stain is absorbed by the water-soluble corneal stroma but not the Descemet’s membrane, giving a descemetocele its characteristic “green donut” appearance

Question 14

What is a Melting/ Malacic Ulcer?

Answer 14

Enzymes from the hosts inflammatory cells break down the cornea so it ‘melts away’
Very very fast process- can happen in hours sometimes

Question 15

Which breeds are predisposed to Melting Ulcers?

Answer 15

Brachycephalic

Question 16

How is Immune mediated superficial punctate keratitis diagnosed?
What does a positive diagnosis look like?

Answer 16

Microscopy/ Ophthalmoscopy- appears as circular lesions/ little dots

Question 17

Which breeds are predisposed to Immune mediated superficial punctate keratitis?

Answer 17

Shetland Sheepdog and the long-haired Dachshund

Question 18

How do we treat Immune mediated superficial punctate keratitis?

Answer 18

With Steroids or Octocyclosporin

Question 19

What is Corneal crosslinking?

Answer 19

Uses UV light to strengthen the cornea in cases of corneal degradation

Question 20

What is Tarsorrhaphy?

Answer 20

surgery to join the eyelids together to allow them to heal- like a see through bandage on the lens

Question 21

What are some of the reasons that a non ulcerative eye disease isn’t healing? (4)

Answer 21

Mechanical irritation
Infection
Malacia (melting)
SCCED

Question 22

How is Eosinophilic Keratitis diagnosed?

Answer 22

Cytology- the only eye disease that shows the presence of eosinophils

Question 23

What species does Eosinophilic Keratitis affect?

Answer 23

Cats and Rabbits ONLY

Question 24

What is the centre of the lens made from?

Answer 24

Proteins (nucleus)

Question 25

What tells us the lens is unstable? (4)

Answer 25

Decreased transparency
Phacodenesis (wobbly lens)
Iridodonesis (wobbly iris)
Aphakic Crescent (clear crescent shape in the pupil where the lens has moved out the way)

Question 26

How do we diagnose problems in the lens?

Answer 26

Usually done via clinical appearance
Also Tonometry may be used to look at high IOP

Question 27

What is a primary cause of Lens Luxation?

Answer 27

Genetic mutation found in terrier breeds

Question 28

What is a secondary cause of Lens Luxation? (5)

Answer 28

Chronic Uveitis (due to zonular degradation)
Glaucoma (stretches the zonules)
Cataract
Trauma
Intraocular Neoplasm

Question 29

What is a Ciliary Zonule and how does this relate to Lens luxation?

Answer 29

The suspensory ligament that connects the lens of the eye to the ciliary body- any damage to this leads to lens luxation

Question 30

In what order does Aqueous fluid flow?

Answer 30

Ciliary Body > Pupil > Iridocorneal Angle (aka drainage angle)

Question 31

What is the blood aqueous barrier and how does this suffer during disease?

Answer 31

the barrier in the ciliary body and iris which separates the eye from systemic circulation- can become leaky when inflamed leading to components of the bloodstream entering that shouldn’t be there- e.g. aqueous humour flare, hyphaema, hypopyon

Question 32

How do we diagnose disease in the anterior chamber of the eye?

Answer 32

Clinical Signs
Tonometry (decreased IOP)

Question 33

What are Vitreal Opacities?

Answer 33

Floating objects inside the vitreous body

Question 34

Apart from Liquefaction, what are the other causes of Vitreal opacities? (7)

Answer 34

Persistant Hyaloid Artery
PHPV
Vitreal Degeneration
Haemorrhage
Vitritis
Asteroid Hyalosis
Synchysis Scintillans

Question 35

What is a persistent hyaloid artery and how does this affect the vitrous?

Answer 35

runs from the disc to the lens- causes local changes of eye background leading to retinal detachment

Question 36

What is PHPV?
(aka PHTVL)

Answer 36

Peristant Hyperplastic Primary Vitreous- developmental anomaly of the eye due to failure of the embryological, primary vitreous and hyaloid vasculature to regress
Causes persistent cataracts & is unusually untreatable

Question 37

Vitritis is _______ and commonly occurs alongside _________?

Answer 37

Inflammation of the Vitreous
Alongside Uveitis

Question 38

What is Asteroid Hyalosis, and what does it appear as?

Answer 38

Another form of Vitral degeneration
Appears as ‘stars’ in the eye that jiggle when the eye moves and then fall back into place

Question 39

How does Synchysis Scintillans differ from Asteroid Hyalosis?

Answer 39

Like asteroid hyalosis but the vitrous is more liquefied so the ‘stars’ do not fall back into place

Question 40

What are some common signs of Acute Glaucoma? (5)

Answer 40

Corneal oedema due to high pressures pushing fluid in
Episcleral Congestion
Epiphora (excessive tears)
Mydriasis (dilated pupil)
Absent menace response due to loss of vision

Question 41

What are some signs of Chronic Glaucoma? (4)

Answer 41

Similar signs to acute as well as…
Haab’s stria (breaks in Descemet’s membrane)
Buphthalmia (enlarged eye)
Lens subluxation (stretching of the globe) leading to Lens Luxation
Optic nerve head cupping (collapses due to high pressures)

Question 42

What is Gonioscopy?

Answer 42

Eye test that checks for signs of glaucoma- Uses a slit lamp to evaluate eye drainage angle- if the drainage angle is blocked or closed it could be due to glaucoma

Question 43

What is the first line of defence to manage Glaucoma?

Answer 43

Carbonic Anhydrase Inhibitors- ability to reduce the secretion of aqueous humour, thereby lowering the intraocular pressure

Question 44

What else can we use to treat Glaucoma apart form carbonic anhydrase inhibitors?

Answer 44

Prostaglandin Analogues- increasing the uveoscleral outflow to reduce IOP