A color guide to the cornea Flashcards
Vascularization - colour
red/pink
Vascularization - causes
Irritants
Chronic diseases - (Canine LPI/pannus and feline EK)
Deposits/Infiltrates - colour
white/yellow
Deposits/Infiltrates - causes
Cholesterol / Calcium
Scar
Abscess
Fluorescein
Oedema - colour
blue- many hues
oedema - causes
Superficial corneal level (ulcers and vascularization) Intraocular disease (uveitis, glaucoma, lens luxation)
pigment - colour
brown/black
pigment - causes
Irritants and chronic dz
scar
Sequestra
eyelid + hair abnormalities that cause vascularization via irritation
Entropion Ectropion Trichiasis Distichiasis Ectopic cilium
Chronic immune mediated diseases - infiltrative
Canine Lymphocytic Plasmacytic Infiltrate (LPI) aka corneal pannus, chronic superficial keratitis (CSK)
Feline Eosinophilic Keratitis (EK)
Chronic immune mediated diseases - non-infiltrative
Canine dry eye (Keratoconjunctivitis Sicca/KCS)
Canine Lymphocytic Plasmacytic Infiltrate (LPI)
Cellular infiltrate and vascularization, +/- pigment
Dorsolateral corneoconjunctiva usually affected first
Eosinophilic keratitis (EK)
Cats (rabbits and horses too)
primary, immune mediated, idiopathic
Cellular infiltrate and vascularization
Dorsolateral corneoconjunctival area usually affected first
Infiltrate is pink to white and in the form of plaques or “clumps”
Eosinophilic keratitis (EK) - make up of the infiltrate
Neutrophils
Plasma cells
Clusters of eosinophils
LPI of dogs and EK of cats - Treatment - dog
topical use of immunomodulators - ciclsporin
Dogs in temperate climates respond fairly well
Dogs in sunny places (or with snow around) do not
LPI of dogs and EK of cats - Treatment - cat
immunomodulators Topical steroid - dexamethasone phosphate maybe ciclosporin Some cats may find it irritating Some cats may not respond very well
LPI of dogs and EK of cats - Treatment - dose rates
start with high freq of application
taper off v.slowly
low maintenance dose
Canine dry eye (KCS – keratoconjunctivitis sicca) - Treatment
Topical ciclosporin bid or sid, long term (for life)
Preservative-free, viscous tears (preservatives are irritants)
Canine dry eye - acute form
Affects young and older dogs
Less mucus and less hyperemia than chronic cases
But often ulcerative
canine dry eye - chronic form leads to…
Scarring
Pigment changes
Vascularization
Lipid infiltrate - appearance
Reflective white crystals in superficial stroma
Lipid infiltrate - Primary form
dystrophy
Most common
No vascularization
In several breeds ie King Charles spaniels, Huskies, etc
Lipid infiltrate - Secondary form
degeneration, accompanied by vascularization
Associated with chronic corneal problems + hypothyroidism
Lipid infiltrate - treatment
might be removed if large (eg affecting vision) but non-painful
Lipid infiltrate - progression
Usually slowly progressive
Dietary control may slow down progression
Topical steroids and estrus can speed up progression
Calcium infiltrate - appearance
Chalky, non-reflective white crystals in superficial stroma
May adopt a reticulated pattern
Calcium infiltrate - Secondary
degeneration
Associated with chronic corneal problems
Accompanied by vascularization
Might need to be removed via keratectomy if painful
can spiculate
Calcium infiltrate - spiculation
Spicules break through epithelium
this causes pain
Corneal Scar
Associated with chronic keratitis, ulcerative keratitis and surgery
May be accompanied by residual vascularization and pigment
Corneal Scar - appearance
Whitish discoloration
Non reflective
Non crystalline
Dull
Corneal abscess
accumulation of WBCs
Enzymes can lead to rapid collagen melting
Not a pocket of fluid (cannot be drained)
oedema - causes
Loss of epithelium
Loss of endothelium
Vascularization (leakage)
oedema - pathogenesis - loss of epithelium
ulcer
oedema - pathogenesis - endothelial damage
Incr intraocular pressure (glaucoma)
infl (uveitis, accompanied by low pressure)
Primary endothelial degeneration (presumed inherited)
Contact (lens, surgery)
oedema - pathogenesis - vascularization
developing vessels leak
pigmentary keratitis of pugs
with medial canthal and lower eyelid entropion
overexposure of the cornea + conjunctiva
Occasionally associated with dry eye (KCS)
v.proliferative pigment response that starts medially
sight impairing to blinding by 2 years of age
Sequestra of cats – Idiopathic and spontaneous
But associated with chronic irritation
commonly in the central cornea (the most vulnerable part)
Medially with medial lower eyelid entropion
Sequestra of cats – Progressive lesion
Light tan discoloration of superficial stroma, intact epithelium
Darkening of lesion, loss of epithelium, vascularization, pain
Hardening and deepening of the lesion
