Eye Pathology II Flashcards
What does a red corneal opacity mean?
Blood Vessels
What does a blue corneal opacity mean?
Oedema
What does a Crystalline White Corneal Opacity Mean?
lipids
What does a black corneal opacity mean?
Pigment
What is a ‘melting ulcer’ ?
rapid degredation and liquefaction of corneal tissue
either from
* bacterial/ fungal infection
* Inflammatory cells from tear film
Also Called Keratomalacia
What is Descemetocele?
Liquefaction of the corneum leads to the underlying Descemets membrane being pushed forward
What are the four clinical signs of Corneal Ulceration?
- Pain- either inflammatory mediators or Blepharospasm
- Conjunctival Hyperaemia- recruitment of leukocytes
- Corneal oedema- loss of epithelium (ingress of water)
- Corneal neovascularisation
blepharospasm= increased blinking rate
What are two examples of internal ocular disease
corneal oedema
- Glaucoma
- Uveitis
What is Blepharospasm?
Involuntary tight closing of the eyelids
What is lipid keratopathy?
Crystalline dense white deposit in the middle of the cornea
What are corneal dystrophies subclassified as?
- Epithelial
- Stromal
- Endothelial
In what dog species is central corneal lipidosis most common in?
Cavaliers, Boxers, Huskies
What is Central Corneal lipidosis?
Excessive accumulation of lipids in corneal fibroblasts
What are corneal deposits usually secondary to?
Metabolic Disease
hyperadrenocorticism, DM, hypothyroidism
What is Feline Corneal Sequestrum usually recognised as?
discrete orange-brown discolouration of the central cornea, affecting one or both eyes
black pigment is absorbed from the feline tear-film
In what two dog breeds is SCEED common in?
Boxers and Pembroke Corgis
In what dog breed is Pannus Keratitis Most Common in?
e.g chronic superficial keratitis
GSD
What does a pannus keratitis lesion mainly look like?
- Superficial Corneal vascularisation
- infiltration of granulation tissue, lymphocytes and plasma cells
- Pigmentation
What does Feline eosinophillic keratitis look like?
- Can be either Unilateral or Bilateral
- Eosinophils are in dense white plaques
- Neovascularisation
What is Glaucoma?
Forcing fluid into the cornea
What is Uveitis?
Inflammation of the endothelial cells
What is Ulceration?
When there is loss of the waterproof barrier
What happens if the endothelial pump in the corneal endothelium fails?
- No pumping fluid from the cornea into the anterior chamber to maintain the partially dehydrated state of the cornea
- Increased intraocular pressure
- Cell death/ inflammation
What four things may cause corneal oedema?
- Endothelial cell loss
- Internal ocular disease (glaucoma, uveitis)
- Ulceration- loss of waterproof barrier
- Limbal disease
What is the affect of stromal liquefaction that reaches descemets membrane?
results in forward bulging
stroma may be lost completely
What are the common causes of corneal ulcers?
- Developmental (irritation/ poor corneal health)
- Inflammation and infection (immune-mediated KCS)
- Dry eye
- Traumatic
What are the diagostic processes for corneal ulcers?
- Magnification/ illumination
- Fluorescein staining for a corneal ulcer
- Schirmer tear test to rule out KCS
What is the definition of a corneal dystrophy?
Defects in the structure and function of one or more corneal components not triggered by injury or systemic disease
What is SCCED characterised by?
Shallow central corneal erosion with a scant oedema and no vascularisation
What factors are implicated in pannus keratitis?
- Age
- Breed
- Gender
- Environmental factors (sunlight exposure)
What occurs in the latent phase of rebuilding epithelial cells over the stroma?
- Apoptosis of cells damaged by wound stimulus
- Fribronectin polymerases provide provisional anchoring to the wound bed
- reduction in adhesion of basal cells to the basement membrane
What occurs in the migration phase of rebuilding epithelial cells over the stroma?
- Leading edge cells flatten out over the wound area and develop filopedia
- migration of entire epithelial sheet over the wound bed
- no cell division at this stage
What occurs in the proliferation phase of rebuilding epithelial cells over the stroma?
- Cells at the periphery of the cornea undrgo mitotic divison whilst the wound bed is migrated over
- Transformation of the basal layers of stratified epithelium and eventually squamous cells
- basement membrane remodelling
What are the three examples of corneal dystrophy?
- Corneal lipid and crystalline deposits
- Corneal deposits secondary to corneal insult
- corneal depositis secondary to metabolic disease
What are two examples of corneal degeneration?
- Felien corneal sequestrum
- SCCED
What are the two examples of keratitis?
- Chronic/ Superficial keratitis
- Feline eosinophillic keratitis
