Final Exam - Cornea Flashcards
what is ciliary flush (neovascularization)?
360° degree deep corneal neovascularization that is pathognomonic for uveitis - these vessels arise in the cornea from an intraocular or deep origin
what is corneal edema?
only blue opacity!!! appears heterogenous or fluffy
what are the only 2 mechanisms that cause corneal edema?
epithelial disruption or endothelial disruption
if you see focal edema as a part of corneal edema, what conditions should you think of?
superficial ulcers, anterior lens luxations, & early corneal endothelial dystrophy
if you see diffuse edema as a part of corneal edema, what conditions should you consider?
think of glaucoma, stromal ulcers, uveitis, endothelial degeneration, or advanced endothelial dystrophy
if you see bullous keratopathy as a part of corneal edema, what conditions should you think of?
diffuse edema that is chronic & severe that can supersaturate the corneal stroma causing sub-epithelial blisters to develop (ulcers frequently occur spontaneously)
what is corneal fibrosis?
corneal scarring - results from stromal collagen contracture & appears as a dull/wispy white, may see ghost vessels from past keratitis, non-painful condition
what is corneal dystrophy/degeneration?
dystrophy most often involving corneal lipids & appears glittery/shiny appears glittery/shiny with degeneration most often involving calcium & appears gritty/chalky - calcific degeneration more often associated with ulceration & pain
what is a descemetocele?
stromal ulcer that reaches the depth of descemet’s membrane where corneal epithelium & stroma are lost
what is deep corneal vascularization?
vessel pattern that occurs in response to deep disease processes (deep/infected ulcers & uveitis) - these vessels are usually straight, can’t be seen crossing the limbus, & don’t extend as far across the cornea as superficial neovascularization
what is a facet?
loss of corneal stroma with intact overlying epithelium, non-staining depression in the cornea - occurs because epithelialization progresses more rapidly than a stromal healing
what is feline corneal sequestrum?
unknown cause of brown or black discoloration - condition results from chronic corneal irritation and/or ulceration
what is the most common cause of feline corneal ulceration?
feline herpesvirus
what is hypopyon?
sterile white blood cell inflammatory reaction within the eye that often settles within the ventral anterior chamber with gravity
what does it mean if hypopyon is present alongside a corneal ulcer?
indicates stromal involvement & infection - emergency!!!
what is keratitis?
inflammation of the cornea
what are keratic precipitates?
cellular adhesions to the endothelium that are pathognomic for uveitis that have a classic appearance that is easily recognized with tiny dots from the mid-portion of the cornea that become larger & denser in the ventral cornea
what is keratomalacia?
corneal melting/melting ulcer/collagenolysis - bacterial/fungal/white blood cell associated enzymatic dissolution of the corneal stroma leading to a creamy, softened appearance to the corneal stroma - medical emergency
what is the limbus?
360° junction between the cornea & sclera/conjunctiva which is the migratory starting point for wound healing & many corneal pathologies - deep to the limbus, the cornea is at its closest point to the uvea (iris) also the site of epithelial stem cells, new blood vessels, & pigment
what is reflex uveitis?
uveitis that is triggered by corneal ulceration specifically - infected ulcers trigger severe reflexive uveitis where as non-infected ulcers trigger mild reflexive uveitis - used to distinguish non-emergent from emergent!!
what does the superficial cornea refer to?
pre-corneal tear film & epithelium, so superficial ulcer indicates a loss of epithelium only (important distinction from stromal qualifier)
what is superficial corneal neovascularization?
vessel pattern seen in superficial disease processes - think of KCS, eyelid disorders, feline herpes, & superficial corneal ulcers - vessels are tree like in appearance & can often be seen crossing the limbus with active vessels fully perfused indicating active/poorly controlled inflammation
what does stromal refer to in regards to the cornea?
entire corneal stroma - loss of stroma and/or presence of white blood cell stromal infiltration is often painful & signals infection - medical emergency!!!
what is white blood cell corneal infiltrate?
white category of corneal opacity that is a sign of active inflammation (keratitis) that is often painful & signals infection with its presence indicating an emergency