The Opaque Eye (Cornea)

Question 1

What causes “blue eye”?

Answer 1

ADENOVIRUS

Inflammation affects endothelium

CORNEAL OEDEMA

Can be reversible in some cases

Question 2

When might a corneal ulcer NOT stain with fluorescein?

Answer 2

Descemetocoele

• No longer stroma present to take up dye

Question 3

Where should you apply fluorescein?

Answer 3

Sclera not cornea

Question 4

Describe the typical appearance of a superficial ulcer

Answer 4

Cornea relatively clear with small focal area of oedema by lesion

Lesion stains +ve fluorescein

Question 5

Describe the appearance of a deep stromal ulcer with descemetocele

Answer 5

Completely cloudy eye
Diffuse corneal oedema

Lesion doesn’t stain with fluorescein

Question 6

What causes dendritic ulcers in cats?

Answer 6

Herpes

Question 7

What is the Seidel test?

What is it used for?

Answer 7

Clear stream of aqueous is visible on the fluorescein covered cornea

For the detection of perforating corneal injuries with active aqueous leakage

Question 8

When should you do cytology?

Answer 8

If suspicious of a bacterial infection or want to do PCR

Question 9

Where on the cornea is healing better?

Why?

Answer 9

Periphery

Vessels arise from limbus so get there faster

Question 10

What part of the cornea does not regenerate?

Answer 10

Endothelium

Question 11

What are the key factors involved in corneal healing?

Answer 11

Vascularisation
Stroma - proliferation of keratinocytes
Endothelium (does not regenerate)

Question 12

What can cause ulcerative disease?

Answer 12

Scratch / FB
KCS 
Lid conformation e.g. if they don’t meet -dry
Mechanical irritation 
- trichiasis
-districhiasis
- ectopic cilia
Entropion/ectropion
Degenerative processes

Question 13

When do you tend to see degenerative processes which affect the cornea?

Answer 13

Mineralisation - calcium, lipid

Older dogs
Endocrine disease
High fat diet
Breed predisposition - Beagles and CKCS

Question 14

Which type or corneal degeneration is associated with pain?

Answer 14

Calcium mineralisation

Question 15

Describe a grade 1 ulcer

Answer 15

epithelial defect

Question 16

Describe a grade 2 ulcer

Answer 16

Persistent epithelial defect

SCCED

Question 17

Describe a grade 3 ulcer

Answer 17

Non-progressive anterior stromal ulcer

Question 18

Describe a grade 4 ulcer

Answer 18

Deep progressive stromal ulcer

Descemetocele

Question 19

Describe a grade 5 ulcer

Answer 19

Corneal perforation and iris prolapse

Question 20

What can cause a superficial ulcer?

Answer 20

Scratch
KCS
Mineralisation with CALCIUM
SCCED

Question 21

What is SCCED

Answer 21

Spontaneous chronic corneal epithelial defect

Superficial ulcer which takes more than a week to heal

Indicates defect in stroma so not healing properly

Question 22

What animal should you NEVER burr and debride?

Why

Answer 22

CATS

Most ulcers caused by FHV so burring etc will put virus further into the stroma

Question 23

What treatment is indicated for dogs with SCCED

Answer 23

Debridement
Burring
Contact lens placement

Question 24

What are some sequelae to progressive corneal ulceration?

Answer 24

Bacterial invasion -> hypopion
Degradation of corneal stroma
Secondary uveitis due to AXON REFLEX - substance P leads to PG release and uveitis

Question 25

What is a melting corneal ulcer?

Answer 25

Droops over the edge Looks yellow - collagenases Caused by increased activity of MMPs proteinases and collagenases

Question 26

What activates a melting corneal ulcer?

Answer 26

Bacteria - Pseudomonas, Staph and strep Fungi Nutrophils Cornea

Question 27

How would you treat a melting corneal ulcer?

Answer 27

Hourly treatment with anti collagenases and antibiotics

Question 28

How can you manage a corneal ulcer medically?

Answer 28

Antibiotics Mydriatic cyclipegic - atropine Anti-inflammatories

Question 29

How can you manage corneal ulcers surgically?

Answer 29

``` Conjunctival graft Corneo-conjunctival transposition Corneal grafting - from donor - biologic collaenous grafting material - amniotic membrane ```

Question 30

What can cause corneal opacity as a result of NON-ULCERATIVE disease?

Answer 30

Superficial or deep keratitis: ``` Eosinophilic CSK Corneal sequestrum Immune mediated keratitis Acute bullous Pigmentary Mineralisation Fibrosis ```

Question 31

What animals get eosinophilic keratitis? How is it diagnosed? How do you treat it?

Answer 31

Cats and horses Cytology White cottage cheese like lesions on the cornea Long term topical steroid use

Question 32

What is chronic superficial keratitis ?

Answer 32

Pannus GSDs Immune mediate keratitis Will lead to complete corneal pigmentation if left untreated Tx local immunosuppressants - optimmune

Question 33

What animals get corneal sequestrums ?

Answer 33

CATS ONLY

Question 34

What causes sequestrums?

Answer 34

Brachys Decreased corneal sensation Chronic irritation FHV Tear film abnormalities

Question 35

What cause would you consider if you saw BVs and pigmentation Bilaterally and affecting the same position of the eye?

Answer 35

Immune mediated

Question 36

What is the go to drug for immune mediated conditions / keratitis?

Answer 36

Optimmune

Question 37

What generally causes corneal oedema?

Answer 37

Breach of barrier of epithelium or endothelium Swelling causes misalignment of fibrils - CLOUDY CORNEA

Question 38

What conditions may result in corneal oedema?

Answer 38

Epithelial defect - ULCER Endothelial degeneration - UVEITIS - GLAUCOMA - CHRONIC LENS LUXATION

Question 39

How long does it take for a small epithelial defect to heal?

Answer 39

24h

Question 40

How long does it take to re-establish thickness of epithelium ?

Answer 40

1 week