A Colour Guide to the Cornea Flashcards
What does redness or pinkness of the cornea suggest? What could possibly have caused this?
Vascularisation - possibly caused by irritants or chronic immune mediated disease.
What are some potential irritants of the cornea?
Entropion, Ectropion, Trichiasis, Distichiasis, Ectopic cilia (what do these all mean?)
What are the two types of chronic immune mediated disease that can lead to vascularisation of the cornea in dogs and cats? Can you think of any examples?
Infiltrative diseases - Lymphocytic plasmocytic infiltrate (LPI) aka. Pannus or Chronic superficial keratitis in dogs, or Eosinophilic keratitis in Cats
Non-infiltrative - Keratoconjuctivitis sicca (KCS) aka. Dry eye
What is Canine Lymphocytic Plasmocytic Infiltrate?
It is a primary immune mediated disease, where there is cellular infiltration, vascularisation and there may be pigmentation. Cytology can be done.
What is eosinophilic keratitis in Cats? What other species does it affect?
Primary immune mediated disease, where there is cellular infiltration and vascularisation. Get infiltration of neutrophils, plasma cells and clusters of eosinophils. Infiltrate is pink/white and forms plaques (may uptake stain) Also can affect horses and rabbits.
How are Canine Lymphocytic Plasmocytic Infiltrate and Eosinophilic keratitiis in Cats treated?
Topical immunomodulators. Dogs: Use ciclosporin (generally respond better in temperate climates). Cats: Topical steroid (dex) - some cats may find irritating or not work. Start high frequency (4-6x daily) then slowly taper.
How is a diagnosis of KCS confirmed?
History (recurring, persistent, occular surface problems), Clinical signs (conjunctivitis, surface dullness, mucous, ulcers), and low STT-1
What is KCS? How is KCS treated?
Aka. Dry eye. Usually primary immune mediated which affects both eyes assymetrically. Treated using topical ciclosporin (Optimmune and Viscous tears). Changes may not be reversible.
What 5 things do you look for improvements in when treating KCS?
- Mucous production, 2. Tear readings, 3. Comfort, 4. Redness, 5. Keratitis
What causes white or yellow discolouration of the cornea? Can you think of any examples?
Deposits and Infiltrates e.g. Cholesterol, Calcium, Corneal scarring and corneal abscesses.
How does lipid infiltration affect the cornea? What does it look like? What is the pathogenesis?
Causes reflective white crystals to form in the superficial stroma. Two forms - primary form is the most common, usually no vascularisation. Secondary form is associated with chronic corneal problems, usually with vascularisation. Usually slowly progressive.
How does calcium infiltration affect the cornea? What does it look like? What is the pathogenesis?
Chalky, non-reflective white crystals. Hard to distinguish from Lipid, may have reticulated pattern. Associated with chronic corneal problems and associated with vascularisation. May be painful.
How does corneal scarring affect the cornea? What does it look like? What is the pathogenesis?
Whiteish discolouration of the cornea, which is non-reflective, non-crystalline and dull. Associated with chronic keratitis, ulcerative keratitis, and surgery.
What is a corneal abscess? Why are they potentially very dangerous? Can they be drained?
Accumulation of WBC in the cornea. The enzymes can potentially lead to corneal melting. They cannot be drained!!!!
What does bluish discolouration of the cornea suggest? In what three ways can this occur (examples?)?
It suggest corneal oedema. 1. Loss of epithelium (e.g. Ulcer), 2. Endothelial damage (e.g. Increased IOP, inflammation), 3. Vascularisation (developing leaky vessels)
