Corneal ulcers

Question 1

what is a corneal ulcer

Answer 1

break in continuity of corneal epithelium with exposure of underlying stroma

Question 2

List 5 ways that the cornea maintains transparency

Answer 2

Smooth optical surface
Relatively dehydrated state
Very regular arrangement of collagen fibrils
Low cell density
No keratin, blood vessels or melanin

Question 3

List 3 cornea pathologies

Answer 3

oedema
vascularisation
pigmentation

Question 4

Describe corneal wound healing

Answer 4

corneal epithelium is self-renewing: continual cell turnover

Question 5

Describe how the cornea heals a superficial ulcer

Answer 5

Epithelial loss -> cells slide rapidly across to cover defect (hours – days): cell proliferation, migration and adhesion
Takes a few days

Question 6

Describe stromal wound healing

Answer 6

Starts once re-epithelialisation is complete
Fibroblasts migrate in & lay down new collagen
Requires vascularisation
Results in scar tissue: remodelling over time

Question 7

List 6 causes of corneal ulcers in dogs

Answer 7

trauma
tear film problem
adnexal conditions
primary corneal disease
infection
neuro disease- facial or trigeminal nerve paralysis

Question 8

what do corneal ulcers secondary to dry eye (KCS) look like

Answer 8

have a circular ‘punched out’ appearance and deteriorate rapidly

Question 9

List the clinical signs of corneal ulceration

Answer 9

Ocular Pain
Conjunctival hyperaemia - a “red eye”
Ocular discharge
Corneal oedema
Reflex uveitis

Question 10

describe the TRIAD of ocular pain

Answer 10

1. Increased lacrimation (high STT)
2. Blepharospasm - closing eye
3. Photophobia - avoiding bright light

Question 11

Describe a superficial corneal ulcer

Answer 11

epithelial loss on
acute onset
painful
sharp distinct border

Question 12

Describe a stromal ulcer

Answer 12

Loss of epithelium and stroma
Acute or chronic
Fluorescein stains walls and floor of ulcer
anterior uveitis common

Question 13

Describe how to tell the difference between a superficial and stromal ulcer

Answer 13

stromal- will see crater in cornea when look at eye from different angle

Question 14

Describe a Descemetocoele

Answer 14

Complete stromal loss - defect down to Descemet’s membrane
Walls of ulcer/crater usually obvious
Don’t take up stain in the middle- look black - shows descements membrane does not take up stain

Question 15

Describe a ‘melting’ corneal ulcer (keratomalacia)

Answer 15

Beware the animal with an acute closed painful eye with copious discharge – probably “melting”
acute- painful
Lots of gelatinous “gloopy” discharge
Ill-defined, rounded, soft edges

Question 16

Describe what melting corneal ulcers look like

Answer 16

ill-defined rounded soft edges
marked corneal oedema
marked anterior uveitis
Can progress rapidly and perforate within hours: ophthalmic emergency

Question 17

Describe the pathogenesis of melting ulcers

Answer 17

Enzymes (proteinases and collagenases) break down or ‘digest’ corneal stroma
2 origins:from cornea itself OR bacterial infection

topical corticosteroids cause local immune suppression and potentiate collagenase activity

Question 18

List 5 questions that we should you ask ourselves when approaching treating a corneal ulcer

Answer 18

How big/deep is it?
Where in the cornea is it?
Does the surrounding cornea look healthy?
Is there an underlying cause?
Is it melting/infected?

Question 19

Decsribe how to treat a superficial corneal ulcer

Answer 19

underlying cause
chloramphenicol drops QID
systemic NSAID
if any reflex uveitis- single drop of atropine

recheck 3-5 days

Question 20

Describe how to treat superficial stromal corneal ulcers

Answer 20

underlying cause
chloramphenicol drops QID
systemic NSAID
if any reflex uveitis- single drop of atropine

recheck 3-5 days

Question 21

what is a complex corneal ulcer

Answer 21

Deep stromal ulcer
Descemetocoele
Perforated ulcer
Melting ulcer

Question 22

What diagnostics should we perform if think corneal ulcer is infected

Answer 22

corneal cytology
corneal swab
care with deep lesion- procedure can cause corneal perforation

Question 23

Describe how to treat melting corneal ulcers

Answer 23

ideally base ABs off C and S
consider systemic ABs
anti-collagenase q2h
systemic NSAID +/- opiod
atropine to effect
may need surgery
monitor closely

Question 24

Describe Anti-collagenases for melting ulcers

Answer 24

serum from same or other animals
OR
N-acetylcysteine - Stromease relatively new licensed product, synthetic alternative to serum

Question 25

Describe how to treat deep ulcers

Answer 25

Intensive medical therapy following general principles
Prompt grafting surgery to prevent corneal perforation
If perforated or referral not possible - enucleation may be required

Question 26

SCCED

Answer 26

spontaneous chronic corneal epithelial defect

Question 27

Describe what a SCCED is

Answer 27

Aka non-healing ulcer, indolent ulcer, ‘Boxer ulcer’
Superficial ulcer that affects middle-aged dogs (>7 years old)
can affect any breed
epithelial loss only - NO stromal involvement

Question 28

what occurs in a SCCED

Answer 28

Characterised by lip of loose epithelium – epithelium grows across but cannot adhere to underlying stroma

Question 29

Describe diagnosis of SCCED

Answer 29

• Signalment: older dogs
• Clinical appearance: superficial, non-adherent epithelium
• Ruling out other underlying causes e.g. ectopic cilium, foreign body, eyelid mass, KCS…

Question 30

Describe how to treat SCCEDs

Answer 30

Need to disrupt the epithelial basement membrane/anterior stroma to allow epithelium-to-stroma attachment – medical treatment alone not enough

Debridement alone OR debridement + keratotomy or Keratectomy

in conjunction with medical treatment

Question 31

Describe the adjunctive medical therapy used to treat SCCEDs

Answer 31

debridement/keratotomy
chloramphenicol
systemic NSAIDs
1-2 drops of atropine

Question 32

List 3 common causes of corneal ulcers in cats

Answer 32

Infection: feline herpesvirus infection (FHV-1)
Trauma (cat fight injuries, FB)
Corneal sequestrum