Opaque eye Flashcards
What is red/pink cornea?
neovascularisation
What can cause neovascularisation of the cornea?
mechanical irritation: eyelid abnormalities, chemical burn
chronic dz: chronic superficial keratitis, eosinophilic keratitis, KCS, immune-mediated keratitis
corneal ulceration
scleritis/episcleritis
granulation tissue
neoplasia
What is white/yellow cornea?
deposit/infiltrate
What causes deposit/infiltrate of the cornea?
lipid
calcium
abscess/infiltrate
scar/fibrosis
fluorescein
What is blue cornea?
oedema
What causes oedema of the cornea?
corneal ulcer
vascularisation (leaky vessels)
intraocular disease: uveitis, glaucoma, lens luxation
What is brown/black cornea?
pigment
What causes pigment of the cornea?
mechanical irritation
sequestrum
pigmentary keratitis
melanoma
FB
corneal perforation with entrapped iris
Why is the healthy cornea transparent?
no blood vessels
no myelinated nerves
no pigment
relatively dehydrated
What are the layers of the cornea?
epithelium
stroma (thickest)
descemet’s membrane
endothelium
How does the epithelium of the cornea heal?
enlargement and sliding of epithelial cells
1-2h
mitosis of epithelial cells
completely healed in 1-2 weeks
How does the stroma of the cornea heal?
Epithelium will heal first: epithelial cell sliding and mitosis (1-2 weeks)
the epithelia will roll over the stromal defect
stroma will need weeks to months to generate new collagen fibers and lamellae
How does the endothelium of the cornea heal?
limited capacity for mitosis
enlarge in size, reduve in numbers and lose their hexogonal appearance
How is vascularisation indicative of corneal healing?
there is a lag phase
and then when healing starts vessels grow about 0.5mm per day
What is important to know about SCCED?
Spontaneous chronic corneal epithelial defect
only type of ulcer that should be debrided, causes a haz layer which stops epithelium from sticking over the stroma = needs to be removed
its always superficial
How does KCS cause corneal opacity?
KCS = dry eye
discharge stick to the cornea
What does a superficial ulcer look like?
similar to scedd w/o haz layer
hard to see with the naked eye
1-2weeks healing
What does a deep ulcer look like?
crater into the eye, in the stroma
What does a descemetocoele look like?
very deep ulcer
single layer left before eye is ruptured: EMERGENCY
oedema around ulcer
florescein + flush: stain doesn’t stain the bottom layer only walls of ulcer
What is a melting/malacic ulcer?
cornea starts degrading/melting away
What is the only type of ulcer you should use steroids on?
immune-mediated superficial punctate keratitis
common in daschund
What shoudl we always consider until proven otherwise with corneal ulcers in cats?
that its feline herpesvirus (dendritic or geographic)
What is a corneal perforation?
ulcer/other that goes through all the layers of the cornea
What are the 6 medical management tx of ulcerative keratitis and when are they used?
topical antibiotic (prophylactic), antiviral, antifungal
topical mydriatic/cycloplegic (vs uveitis/myotic pupil)
topical anti-collegenase (vs melting ulcer enzyme)
systemic analgesic (pain)
+/- topical immunomodulator
+/- topical anti-inflammatory (but risk of delayed corneal healing)
What are the non-medical management treatments for ulcerative keratitis?
corneal collagen crosslinking
surgical grafting
tarsorrhaphy (partially close eyelid)
3rd eyelid flap
contact lens
Why could a corneal ulcer be non-healing?
aka longer than 2 weeks on appropriate tx
mechanical irritation
infection
malacia/melting
SCCED
neoplasia
What is eosinophilic keratitis?
immune mediated
in rabbits and cats
plaque like white/pink cottage cheese in corners of the eye
only 1 eosinophil is diagnostic!
steroids indicated
What is chronic superficial keratitis?
pannus
grey-pink film over the eye that can become opaque with progression
immune mediated, steroids indicated
What is corneal sequestrum?
piece of cornea that has died off and taken brown discoloration
could be ulcerative around the edge or started off as an ulcer
What is an acute bullous keratopathy?
severe form of corneal oedema
rare indication for 3rd eyelid closure
What is pigmentary keratitis?
black or brown pigment is deposited on the cornea
caused by chronic inflammation or irritation
What is mineral deposition on the cornea?
calcium/lipid
have a sparkly look, white
part of degenerative process
What is endothelial degeneration?
corneal oedema from being compromised or from age/genetics
when it can no longer compensate
blue or cloudy
What are the types of corneal oedema?
endothelial degeneration
uveitis
lens luxation
glaucoma
What are the clinical signs of lens instability?
decreased transparency (corneal oedema)
phacodonesis
iridodonesis
aphakic crescent
What is phacodonesis?
wobbly lens
What is iridodonesis?
wobbly iris
What is aphakic crescent?
clear crescent shape in the pupil where lens has moved “out of the way”`
What are the diagnostic tests used for disease of the lens?
clinical appearance
tonometry (IOP may be high)
- lens luxation = emergency
What are the primary lens luxation causes?
genetic mutations (especially terrier breeds)
What are the secondary lens luxation causes?
chronic uveitis (zonular degradation)
glaucoma (stretched zonules)
cataract (secondary uveitis)
trauma (mech. rupture, uveitis)
intraocular neoplasm
What is the path of the aqueous humour flow?
ciliary body -> pupil -> iridocorneal angle (drainage angle)
in the anterior chamber
What is the blood aqueous barrier?
epithelial barrier in ciliary body and iris
separates the eye from systemic circulation
becomes “leaky” when inflammed
What are clinical signs of uveitis?
aqueous humor flare
hyphaema
hypopyon
What are diagnostic tests used for anterior chamber disease?
clinical signs
tonometry (usually decreased due to loss of function from infl.)
What is liquefaction?
disease of the vitreous
goes from gel to liquid
causes vitreal opacity
What is persistent hyaloid artery?
part of foetal vasculature that should regress after a few weeks of life
most cases not clinically relevant
is an opacity in the vitreous
What is PHTVL/PHPV?
vitreal opacity
persistent hyperplasia of vitreous
embryon vasculature that didn’t regress
no tx unless client wants cataract sx
What is vitreal degeneration?
in older ptx
vitreous humour shrinks causing condensed vitreous materal/ “floaters”
What should we know about vitreal haemorrhage?
generally self-resolves
turnover of vitreous is very slow and can take a few months to heal
What is vitritis?
cellular infiltration
inflammation from surrounding tissues
What is asteroid hyalosis?
cholesteol clumps in the vitreous that jiggle but keep position
caused by age
What is synchysis scintillans?
cholesterol crystals that have a snowball effect
degenerative condition
What are the clinical signs of acute glaucoma?
corneal oedema
episcleral congestion
conjunctival hyperaemia
epiphora
mydriasis
aqueous flare
abscent menace
What are the clinical signs of chronic glaucoma?
signs of acute glaucoma
optic nerve head cupping
Haab’s stria
buphtalmia
lens subluxation/luxation
What is a normal tonometry result?
10-25
if 25-30: mild stage, low pressure of day, false elevation, poor restraint
How do we know how to interpret tonometry results?
use alongside the clinical signs
What is congenital glaucoma?
aqueous humour can’t drain properly and young eyes stretch easily
once enlarged won’t go back and vision is likely lost
What is an open/closed angle during glaucoma?
open: fibers of pectinate in the iridocorneal angle are normal but tibecular meshwork is abnormal stopping the draining of the aqeuous humour
closed: loss of ligament fibers, aqueous humour has nowhere to go
What are causes of secondary glaucoma?
lens luxation (lens blocks drainage)
uveitis
What are the medical management options for glaucoma?
carbonic anhydrase inhibitors
(stops enzyme producing aqueous humour)
prostaglandin analogues (increases outflow)
adrenergic agents (when no cvs/syst. issues it helps potentiate CAI)
cholinergic agonists
osmotic agents
