Corneal ulcers Flashcards
(32 cards)
what is a corneal ulcer
break in continuity of corneal epithelium with exposure of underlying stroma
List 5 ways that the cornea maintains transparency
Smooth optical surface
Relatively dehydrated state
Very regular arrangement of collagen fibrils
Low cell density
No keratin, blood vessels or melanin
List 3 cornea pathologies
oedema
vascularisation
pigmentation
Describe corneal wound healing
corneal epithelium is self-renewing: continual cell turnover
Describe how the cornea heals a superficial ulcer
Epithelial loss -> cells slide rapidly across to cover defect (hours – days): cell proliferation, migration and adhesion
Takes a few days
Describe stromal wound healing
Starts once re-epithelialisation is complete
Fibroblasts migrate in & lay down new collagen
Requires vascularisation
Results in scar tissue: remodelling over time
List 6 causes of corneal ulcers in dogs
trauma
tear film problem
adnexal conditions
primary corneal disease
infection
neuro disease- facial or trigeminal nerve paralysis
what do corneal ulcers secondary to dry eye (KCS) look like
have a circular ‘punched out’ appearance and deteriorate rapidly
List the clinical signs of corneal ulceration
Ocular Pain
Conjunctival hyperaemia - a “red eye”
Ocular discharge
Corneal oedema
Reflex uveitis
describe the TRIAD of ocular pain
- Increased lacrimation (high STT)
- Blepharospasm - closing eye
- Photophobia - avoiding bright light
Describe a superficial corneal ulcer
epithelial loss on
acute onset
painful
sharp distinct border
Describe a stromal ulcer
Loss of epithelium and stroma
Acute or chronic
Fluorescein stains walls and floor of ulcer
anterior uveitis common
Describe how to tell the difference between a superficial and stromal ulcer
stromal- will see crater in cornea when look at eye from different angle
Describe a Descemetocoele
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
Describe a ‘melting’ corneal ulcer (keratomalacia)
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
Describe what melting corneal ulcers look like
ill-defined rounded soft edges
marked corneal oedema
marked anterior uveitis
Can progress rapidly and perforate within hours: ophthalmic emergency
Describe the pathogenesis of melting ulcers
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
List 5 questions that we should you ask ourselves when approaching treating a corneal ulcer
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?
Decsribe how to treat a superficial corneal ulcer
underlying cause
chloramphenicol drops QID
systemic NSAID
if any reflex uveitis- single drop of atropine
recheck 3-5 days
Describe how to treat superficial stromal corneal ulcers
underlying cause
chloramphenicol drops QID
systemic NSAID
if any reflex uveitis- single drop of atropine
recheck 3-5 days
what is a complex corneal ulcer
Deep stromal ulcer
Descemetocoele
Perforated ulcer
Melting ulcer
What diagnostics should we perform if think corneal ulcer is infected
corneal cytology
corneal swab
care with deep lesion- procedure can cause corneal perforation
Describe how to treat melting corneal ulcers
ideally base ABs off C and S
consider systemic ABs
anti-collagenase q2h
systemic NSAID +/- opiod
atropine to effect
may need surgery
monitor closely
Describe Anti-collagenases for melting ulcers
serum from same or other animals
OR
N-acetylcysteine - Stromease relatively new licensed product, synthetic alternative to serum
