A color guide to the cornea Flashcards by Saul Levy

Vascularization - colour

red/pink

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Vascularization - causes

Irritants

Chronic diseases - (Canine LPI/pannus and feline EK)

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Deposits/Infiltrates - colour

white/yellow

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Deposits/Infiltrates - causes

Cholesterol / Calcium
Scar
Abscess
Fluorescein

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Oedema - colour

blue- many hues

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oedema - causes

Superficial corneal level (ulcers and vascularization) 
Intraocular disease (uveitis, glaucoma, lens luxation)

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pigment - colour

brown/black

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pigment - causes

Irritants and chronic dz
scar
Sequestra

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eyelid + hair abnormalities that cause vascularization via irritation

Entropion 
Ectropion 
Trichiasis 
Distichiasis 
Ectopic cilium

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Chronic immune mediated diseases - infiltrative

Canine Lymphocytic Plasmacytic Infiltrate (LPI) aka corneal pannus, chronic superficial keratitis (CSK)
Feline Eosinophilic Keratitis (EK)

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Chronic immune mediated diseases - non-infiltrative

Canine dry eye (Keratoconjunctivitis Sicca/KCS)

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Canine Lymphocytic Plasmacytic Infiltrate (LPI)

Cellular infiltrate and vascularization, +/- pigment

Dorsolateral corneoconjunctiva usually affected first

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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”

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Eosinophilic keratitis (EK) - make up of the infiltrate

Neutrophils
Plasma cells
Clusters of eosinophils

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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

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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