The Opaque Eye (Cornea) Flashcards
What causes “blue eye”?
ADENOVIRUS
Inflammation affects endothelium
CORNEAL OEDEMA
Can be reversible in some cases
When might a corneal ulcer NOT stain with fluorescein?
Descemetocoele
- No longer stroma present to take up dye
Where should you apply fluorescein?
Sclera not cornea
Describe the typical appearance of a superficial ulcer
Cornea relatively clear with small focal area of oedema by lesion
Lesion stains +ve fluorescein
Describe the appearance of a deep stromal ulcer with descemetocele
Completely cloudy eye
Diffuse corneal oedema
Lesion doesn’t stain with fluorescein
What causes dendritic ulcers in cats?
Herpes
What is the Seidel test?
What is it used for?
Clear stream of aqueous is visible on the fluorescein covered cornea
For the detection of perforating corneal injuries with active aqueous leakage
When should you do cytology?
If suspicious of a bacterial infection or want to do PCR
Where on the cornea is healing better?
Why?
Periphery
Vessels arise from limbus so get there faster
What part of the cornea does not regenerate?
Endothelium
What are the key factors involved in corneal healing?
Vascularisation
Stroma - proliferation of keratinocytes
Endothelium (does not regenerate)
What can cause ulcerative disease?
Scratch / FB KCS Lid conformation e.g. if they don’t meet -dry Mechanical irritation - trichiasis -districhiasis - ectopic cilia Entropion/ectropion Degenerative processes
When do you tend to see degenerative processes which affect the cornea?
Mineralisation - calcium, lipid
Older dogs
Endocrine disease
High fat diet
Breed predisposition - Beagles and CKCS
Which type or corneal degeneration is associated with pain?
Calcium mineralisation
Describe a grade 1 ulcer
epithelial defect
Describe a grade 2 ulcer
Persistent epithelial defect
SCCED
Describe a grade 3 ulcer
Non-progressive anterior stromal ulcer
Describe a grade 4 ulcer
Deep progressive stromal ulcer
Descemetocele
Describe a grade 5 ulcer
Corneal perforation and iris prolapse
What can cause a superficial ulcer?
Scratch
KCS
Mineralisation with CALCIUM
SCCED
What is SCCED
Spontaneous chronic corneal epithelial defect
Superficial ulcer which takes more than a week to heal
Indicates defect in stroma so not healing properly
What animal should you NEVER burr and debride?
Why
CATS
Most ulcers caused by FHV so burring etc will put virus further into the stroma
What treatment is indicated for dogs with SCCED
Debridement
Burring
Contact lens placement
What are some sequelae to progressive corneal ulceration?
Bacterial invasion -> hypopion
Degradation of corneal stroma
Secondary uveitis due to AXON REFLEX - substance P leads to PG release and uveitis
What is a melting corneal ulcer?
Droops over the edge
Looks yellow - collagenases
Caused by increased activity of MMPs proteinases and collagenases
What activates a melting corneal ulcer?
Bacteria - Pseudomonas, Staph and strep
Fungi
Nutrophils
Cornea
How would you treat a melting corneal ulcer?
Hourly treatment with anti collagenases and antibiotics
How can you manage a corneal ulcer medically?
Antibiotics
Mydriatic cyclipegic - atropine
Anti-inflammatories
How can you manage corneal ulcers surgically?
Conjunctival graft Corneo-conjunctival transposition Corneal grafting - from donor - biologic collaenous grafting material - amniotic membrane
What can cause corneal opacity as a result of NON-ULCERATIVE disease?
Superficial or deep keratitis:
Eosinophilic CSK Corneal sequestrum Immune mediated keratitis Acute bullous Pigmentary Mineralisation Fibrosis
What animals get eosinophilic keratitis?
How is it diagnosed?
How do you treat it?
Cats and horses
Cytology
White cottage cheese like lesions on the cornea
Long term topical steroid use
What is chronic superficial keratitis ?
Pannus
GSDs
Immune mediate keratitis
Will lead to complete corneal pigmentation if left untreated
Tx local immunosuppressants - optimmune
What animals get corneal sequestrums ?
CATS ONLY
What causes sequestrums?
Brachys
Decreased corneal sensation
Chronic irritation
FHV
Tear film abnormalities
What cause would you consider if you saw BVs and pigmentation Bilaterally and affecting the same position of the eye?
Immune mediated
What is the go to drug for immune mediated conditions / keratitis?
Optimmune
What generally causes corneal oedema?
Breach of barrier of epithelium or endothelium
Swelling causes misalignment of fibrils
- CLOUDY CORNEA
What conditions may result in corneal oedema?
Epithelial defect - ULCER
Endothelial degeneration
- UVEITIS
- GLAUCOMA
- CHRONIC LENS LUXATION
How long does it take for a small epithelial defect to heal?
24h
How long does it take to re-establish thickness of epithelium ?
1 week
