Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Y4 SA - Ophthalmology > Corneal ulcers > Flashcards

Corneal ulcers Flashcards

(48 cards)

Start Studying
1
Q

Ulcer definition

A

= discontinuity or break in a bodily membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Corneal ulcer definition

A

= break in continuity of corneal epithelium with exposure of underlying stroma
aka ulcerative keratitis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Structure of cornea

A
  • stratified epithelium and its basement membrane
  • collagenous stroma (~90% of the cornea thickness)
  • descemet’s membrane
  • endothelium
  • all about 0.5mm
  • nerve endings in epithelium and stroma
    – superficial lesions can be more painful than deep lesions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Corneal physiology

A

Corneal transparency is due to:
- smooth optical surface
- relatively dehydrated state
- very regular arrangement of collagen fibres
- low cell density
- no keratin, blood vessels or melanin

Relatively dehydrated state is due to:
- epithelium above which has tight junctions to prevent water from tear film entering
- endothelium below which has Na/K ATPase pump: pumps ions from stroma into aqueous humour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Corneal pathology - oedema, vascularisation & pigmentation

A

Oedema
- break of or dysfunction barrier layers (epithelium and endothelium)
-> increased water content
-> distorts collagen fibrils, creating opacity

Vascularisation
- superficial or deep in-growth of blood vessels
- promotes healing (but can increase scarring)

Pigmentation
- non-specific response to corneal insult
- takes a while to develop, therefore pigmentation is a sign of a chronic problem

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Corneal wound healing - epithelium

A

Corneal epithelium is self-renewing: continual cell turnover
- proliferation of basal epithelial cells at limbus (mitosis)
- movement of peripheral cells towards centre of cornea
- epithelial cells lost from corneal surface into tear film

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Healing of a superficial ulcer (epithelial defect only)

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Corneal wound healing: vascularisation

A
  1. conjunctival hyperaemia (± episcleral hyperaemia)
  2. endothelial budding (4-7d lag period) (i.e. if it doesn’t heal within the 1st few days it will get endothelial budding at the limbus)
  3. superficial corneal blood vessels (± deep corneal blood vessels)
  4. lesion resolves and blood vessels become hypoperfused
  5. corneal ‘ghost vessels’ (visible only with magnification)

Vessels grow at ~0.5-1mm/day

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Corneal healing - stroma

A

Stromal wound healing
- starts once re-epithelialisation is complete (i.e. once the epithelium is completely sealed over)
- fibroblasts migrate in and lay down new collagen
- requires vascularisation
- results in scar tissue: remodelling over time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Broad causes of corneal ulcers in dogs

A
  • trauma
  • tear film problem e.g. KCS
  • adnexal conditions i.e. involving eyelids, eyelashes and conformation
  • primary corneal dz e.g. SCCEDS
  • infection
  • neurological dz e.g. facial or trigeminal nerve paralysis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Causes of corneal ulcers - trauma

A
  • common
  • FB, abrasions, laceration, chemical injury (serious but uncommon)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Causes of corneal ulcers - tear film problems

A
  • quantitative lack of tears -> KCS, very common in dogs
  • qualitative tear film problem -> less common
  • NB ulcers secondary to dry eye often have a circular ‘punched out’ appearance and deteriorate rapidly
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Causes of corneal ulcers - eyelid problems

A
  • entropion (inturning of eye)
  • eyelid mass
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Causes of corneal ulcers - eyelash problems

A
  • distichia
  • ectopic cilium
  • NB distichia are more common than ectopic cilia, may see both together
  • distichia may or may not cause irritation and are less likely to cause ulceration
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Causes of corneal ulcers - brachycephalic conformation, examples

A
  • macropalpebral fissure resulting in lagophthalmos and exposed cornea
  • medial entropion causing chronic corneal trauma and ulceration
  • trichiasis resulting from pronounced nasal fold
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is SCCED?

A

= spontaneous chronic corneal epithelial defect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Causes of corneal ulceration - infection

A

Bacterial keratitis (& occasionally fungal) in dogs & cats
- usually secondary to trauma to allow colonisation

Feline herpes-virus 1
- virus replicates within corneal epithelial cells
- URT dz, conjuncitivitis, ulcerative and non-ulcerative keratitis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What parts of an ophthalmic examination are most relevant to the diagnosis of corneal ulceration?

A

Hands-off examination
- signs of pain
- nature of any discharge
- eyelid conformation

Palpebral ± corneal reflex

STT
- unless risk of rupture
- ulcers will increase tears

Examine anterior segment with focal light source ± magnification
- look at ulcer itself and health of surrounding cornea
- careful examination of eyelids

Distant direct
- check for reflex uveitis
– when the iris goes into spasm secondary to the ulcer you can end up with a small pupil

Fluorescein staining
- orange dye that stains corneal stroma green
- no uptake by intact corneal epithelium or by Descemet’s membrane
- fluorescein strips preferable
– touch onto bulbar conjunctiva
– always flush: water, saline or false tears
- use blue light to highlight dye uptake

Corneal cytology & C&ST
- if suspect infected

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

CS of corneal ulceration

A

Pain - classic triad of ocular pain
- increased lacrimation (high STT)
- blepharospasm: closing eye
- photophobia: avoiding bright light

Conjunctival hyperaemia
- a ‘red eye’

Ocular discharge

Corneal oedema

Reflex uveitis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is a corneal facet?

Study These Flashcards
A
  • a stromal deficit that has epithelialised (fluorescein negative)
21
Q

Superficial cornea ulcer - what is it? signs?

Study These Flashcards
A
  • epithelial loss only
  • acute onset
  • painful (higher density of nerve endings in superficial layers of cornea)
  • sharp distinct borders
  • minimal corneal inflammatory response
  • ± reflex uveitis
22
Q

Stromal ulcer - what is it? signs?

Study These Flashcards
A
  • loss of epithelium and stroma
  • acute or chronic
  • fluorescein stains walls and floor of ulcer
  • superficial stromal or deep stromal
  • anterior uveitis common
  • loss of stroma will distort contours of cornea -> visible crater
23
Q

Descemetocoele - what is it? signs?

Study These Flashcards
A
  • acute or chronic
  • complete stromal loss -> defect down to Descemet’s membrane
  • walls of ulcer/crater usually obvious
  • Descemet’s membrane is 10-15µm, similar to cling film
  • if you see it bulging upwards it is likely the eye is not far from popping
24
Q

Descemetocoele - fluorescein staining pattern

Study These Flashcards
A
  • walls stain positive (exposed stroma)
  • descemet’s membrane doesn’t stain with fluorescein
  • floor/base of ulcer looks black or clear
  • beware of false positives -> always flush the fluorescein
25
Melting corneal ulcers - keratomalacia - signs
- beware of the animal with an acute closed painful eye with copious discharge: probs 'melting' - acute, painful - lots of gelatinous 'gloopy' discharge - ill-defined, rounded, soft edges: like melting butter/candle wax = infected ulcer - variable appearance: varying amounts of stromal involvement - marked corneal oedema - marked anterior uveitis (pain, mitosis, hypopyon, low IOP - can progress rapidly and perforate within hours: ophthalmic emergency
26
Melting ulcers - pathogenesis
Enzymes (proteinases and collagenases) break down or 'digest' corneal stroma 2 origins - cornea itself: epithelial cells, stromal fibroblasts, WBCs - bacterial infection e.g. pseudomonas sp, beta-haemolytic streptococcus sp Topical corticosteroids cause local immune suppression and potentiate collagenase activity
27
Treatment of corneal ulcers
Depends on ulcer depth, underlying cause and whether or not it is infected Factors to consider - how big/deep it is - where in the cornea it is - is the surrounding cornea healthy - is there any underlying cause - is it melting/infected E.g. 2 stromal ulcers with melanosis and vascularisation: chronic corneal dz -> look for underlying problem e.g. dry eye, conformation
28
Tx of simple superficial ulcer
Identify & tx underlying case Prevent/tx secondary infection - e.g. chloramphenicol drops QID - antibiotics used as a prophylaxis for infection - once the stroma is exposed it is prone to infection - chloramphenicol: not licensed but no topical antibiotic licensed for corneal ulcer Analgesia - e.g. systemic NSAID - topical LA for analgesia delays healing so do not use Tx any reflex uveitis (/small pupil) - single drop atropine usually enough Additional support? ± E-collar Arrange re-check and safety net - re-check in 3-5d, sooner if any concerns
29
Tx of superficial stromal ulcers
- similar principles to superficial epithelial ulcers - monitor closely: any stromal ulcer can become complex - take care esp in brachys - check every 1-2d initially
30
Treatment of complex corneal ulcers (& what are complex ulcers?)
What is a 'complex' ulcer? - deep stromal ulcer - descemetocoele - perforated ulcer - melting ulcer All require intensive tx ± surgery All make good referrals if an option
31
Diagnostics if suspect ulcer is infected/melting
Corneal cytology - gently scrape margin of ulcer (not base) - use blunt end of scalpel or cytobrush Corneal swab - bacterial C&ST - swab margin of ulcer (not base) Care with very deep lesions - procedure can cause corneal perforation
32
Tx principles for melting ulcers
Identify & tx underlying cause - treat as infected Tx secondary infection - ideally based on cytology/C&ST - topical FQ e.g. ofloxacin q2h - anticollagenase q2h - consider systemic antibiotics Analgesia - e.g. systemic NSAID ± Opioid - topical LA for analgesia delays healing so do not use Tx any reflex uveitis (/small pupil) - atropine to effect Anti-collagenases - apply every 1-2h for 24h then gradually reduce - serum: from same or another animal -- take e.g. 10ml blood into serum tubes, leave to clot for 30mins -- spin down and extract serum, place in plain tubes/dropper bottles -- keeps in fridge for 1w, freezer for 6m - N-acetylcysteine (Stromese), relatively new licensed product, synthetic alternative to serum Additional support? - may need sx ± E-collar Arrange re-check and safety net - monitor closely ± hospitalise - monitor every day to start with
33
Tx of deep ulcers
Intensive medical therapy following general principles Prompt grafting sx to prevent corneal perforation - provide immediate tectonic support - provide blood supply - may need referral: best performed with magnification and microinstrumentation If perforated or referral not an option, enucleation may be required
34
Graft options/techniques
- conjunctival pedicle graft - cornea-conjunctival transposition graft
35
What is a SCCED? signalment? signs?
= spontaneous chronic corneal epithelial defect - aka non-healing, indolent ulcer - 'boxer ulcer' - superficial ulcer that affects middle-aged dogs (>7y) - can affect any breed (esp Boxers and corgis) - usually unilateral (but can be bilateral, recurrent)
36
SCCED - characterisation
- epithelium loss only - no stromal involvement - characterised by lip of loose epithelium: epithelium grows across but cannot adhered to underlying stroma
37
SCCED vs simple superficial ulcer - fluorescein staining pattern
Simple superficial ulcer - fluorescein stops at edges SCCED - indistinct, irregular border which under-runs with fluorescein - variable inflammatory response: from no neovascularisation to granulation tissue ++
38
SCCED diagnosis
Diagnosis based on - signalment: older dogs - clinical appearance: superficial, non-adherent epithelium - ruling out other underlying causes e.g. ectopic cilium, FB, eyelid mass, KCS
39
SCCED tx
Need to disrupt the epithelial basement membrane/anterior stroma to allow epithelium-to-stroma attachment -> medical tx alone not enough Debridement alone - removes loose epithelium Debridement + keratotomy or keratectomy - procedures involving corneal stroma All in conjunction with medical tx - same principles as for superficial ulcers
40
SCCED tx - debridement
- apply topical anaesthetic eye drops - sterile cotton bud - gentle bud firm action to remove all loose epithelium - true extent of ulcer becomes apparent, don't worry - only the abnormal epithelium will rub off, but ulcer can become much larger - success rate: <50% heal with debridement and medical tx
41
SCCED tx - keratotomy
Keratotomy = to incise cornea Grid keratotomy - sedation often required - debride 1st - 25-27G needle, bevel up - needle parallel to corneal surface, drag (don't push) - cross-hatch of superficial lines 1mm apart from clear cornea to clear cornea (i.e. debrided area + 1-2mm into surrounding normal cornea) Success rate up to 85%
42
SCCED tx - diamond burr keratectomy
Keratectomy = to incise cornea Success rate 85-90%
43
SCCEDS: adjunctive medical tx
Similar to simple superficial ulcer Identify and tx underlying cause - debridement/keratotomy Prevent/tx secondary infection - e.g. chloramphenicol QID Analgesia - e.g. systemic NSAID Tx any reflex uveitis - 1-2 drops of atropine usually enough Additional support? - ± bandage contact lens ± E-collar Arrange re-check and safety net - check weekly, sooner if concerned
44
SCCED: keratectomy
- requires anaesthetic and magnification/expertise - advanced technique: cornea is <0.5mm thick - 100% success rate
45
SCCED tx summary
- O education important - debridement/keratotomy procedures can be repeated after 10-14d - offer referral if not healing after 1-2 procedures - NB debridement and keratotomy procedures are specific to superficial ulcers with non-adherent epithelium --> contraindicated in all other types of ulcers
46
Ulcers in cats - aetiopathogenesis
- similar to dogs with several differences - eyelid and eyelash disorders occur but are less common - dry eye uncommon
47
Ulcers in cats - common causes
- infection: feline herpesvirus infection (FHV-1) - trauma (cat fight injuries, FB) - corneal sequestrum
48
Non-healing ulcers in cats - tx
- gentle debridement with cotton bud and contact lens fine - keratotomy techniques for SCCEDs predispose to sequestrum formation -> never grid a cats cornea

Y4 SA - Ophthalmology (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions