What occurs because epithelialization occurs more rapidly than stromal healing resulting in a non-staining depression in the cornea?
Facet formation: Loss of corneal stoma with intact overlying epithelium
What causes blue opacity of the cornea?
What is 360deg deep corneal neovascularization that is pathognomic for uveitis?
What is one cause of white corneal opactiy and is a sign of active inflammation, which is often painful and signifies an ocular emergency?
WBC corneal infiltration
What is the brown or black discoloration resulting from chronic corneal irritation and/or ulceration, commonly caused by corneal ulceration from feline herpes virus?
Feline Corneal Sequestrum
What are the 4 factors that allow the cornea to stay clear?
1. It is avascular
2. Non-myelinated nerves
3. Dehydrated (Epithelium= barrier to tear film, Endothelium= active pump and barrier to aqueous humor)
4. Ordered cell arrangement
How long does epithelial healing take, even with complete loss? How long does stromal healing, resulting in fibrosis, take? How long does it take for a descemtocele to heal?
Epi: 7 days or less
Stoma: Days to weeks
Descemetocele: Weeks to Months
What is causing the focal edema seen here (inside the dotted circle)?
Anterior lens luxation
Generalized corneal edema can occur from a reduction in ________ cell numbers. This can occur due to canine adenoviral hepatitis or be an aging change.
T/F: Canine glaucoma and uveitis can cause generalized corneal edema.
What are the 2 patterns of corneal vascularization that cause a red corneal opacity?
Deep vessels (ciliary flush/Crown of Thorns)
How long does it take from the insult for vessels to start growing (i.e. for neovascularization to occur)? How quickly do they progress and toward what do they grow?
1mm per day
Toward the stimulus
What does a chronic stimulant irritating the cornea cause? (It is common with indolent ulcers)
Granulation tissue formation (dense, raised collection of superficial vessels)
T/F: When neovacularization of the cornea occurs, the superficial vessels progress more slowly than the deep ones. Deep corneal vesssels also cross the limbus while superficial vessels do not.
False, deep neovascularization progresses slower and deep vessels do not cross the limbus
What are the 3 variations of white corneal opacities? What do they look like?
WBC infiltration- yellow or green hue
Fibrosis - gray or wispy features
Crystalline or chalky white - mineral or lipid, dystrophy or degeneration
What characterized WBC infiltration of the cornea? What does it indicate?
Signals corneal infection (also associated w/uveitis)
Is corneal fibrosis painful?
It is caused by disordered collagen scattering light
What is causing these white opacities?
a. Calcium (left), Lipid (right)
b. Fibrosis (left), Calcium (right)
c. Lipid (left), Fibrosis (right)
d. Lipid (left), Calcium (right)
d. Lipid (left), Calcium (right)
Caused by dystophy or degeneration
What are the 2 broad causes for brown or black corneal opacities?
Pigment (melanin) in the epithlial or endothelial layer
Feline corneal sequestrum
This is a dog who is undergoing treatment for KCS. What are the arrows A, B, and C indicating?
B. Superficial vessels
V. Epithelial pigment
What is the only cause for tan or greasy punctate? What disease process is this pathognomic for?
Keratic precipitates (cellular and fibrinous adhesions to the endothelial surface)
A superficial corneal ulcer describes a loss of the corneal ________ without any loss of corneal ________. A simple or uncomplicated corneal ulcer heals in ____ days while a complex or complicated corneal ulcer heals in ____ days.
A superficial corneal ulcer describes a loss of the corneal EPITHELIUM without any loss of corneal STROMA. A simple or uncomplicated corneal ulcer heals in <7 days while a complex or complicated corneal ulcer heals in >7 days.
What is the canine-specific form of complex corneal ulceration in which the epithelium fails to adhere to the stroma? What breeds get this?
Indolent Ulcer / Spontaneous Chronic Corneal Epithelium Defect (SCCED)
What nerve, in addition to certain cytokines, causes direct stimulation of the ciliary body inducing spasm, pain, and disruption of the blood ocular barrier? What is this condition called?
What is the softening of the cornea due to collagenolysis from an infection?
"Melting Corneal Ulcer"
What bacteria is most commonly the trigger for collagenolysis?
What is a devitalized portion of corneal stoma called?
What breed is most commonly affected by Pigmentary Keratitis?
Presence suggests superficial infection
What are the 4 brachycephalic risk factors for corneal ulcers?
Decreased corneal sensitivity
Tear film abnormalities
Why should you never use any type of topical steroid in cases of ulcerative keratitis (2 reasons)?
Enhanced corneal destruction