Final: Ophthalmology - Cornea, Uvea Flashcards
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?
Corneal edema
What is 360deg deep corneal neovascularization that is pathognomic for uveitis?
Ciliary flush/neovascularization
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?
- It is avascular
- Non-myelinated nerves
- Dehydrated (Epithelium= barrier to tear film, Endothelium= active pump and barrier to aqueous humor)
- 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.
Endothelial
T/F: Canine glaucoma and uveitis can cause generalized corneal edema.
True
What are the 2 patterns of corneal vascularization that cause a red corneal opacity?
Superficial vessels
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?
3 days
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?
PAIN
Signals corneal infection (also associated w/uveitis)
Is corneal fibrosis painful?
No
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?
A. Fibrosis/scarring
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)
Uveitis
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)
Boxers
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?
Trigeminal nerve
Reflex uveitis
What is the softening of the cornea due to collagenolysis from an infection?
Keratomalacia
“Melting Corneal Ulcer”
What bacteria is most commonly the trigger for collagenolysis?
Pseudomonas
What is a devitalized portion of corneal stoma called?
Sequestrum
What breed is most commonly affected by Pigmentary Keratitis?
Pug
Presence suggests superficial infection
What are the 4 brachycephalic risk factors for corneal ulcers?
Ocular prominence
Decreased corneal sensitivity
Adnexal abnormalities
Tear film abnormalities
Why should you never use any type of topical steroid in cases of ulcerative keratitis (2 reasons)?
Delayed healing
Enhanced corneal destruction
What is the most important part of your approach to corneal ulceration (if possible)?
Find the underlying cause (irritants, infection or trauma)
What is the treatment protocol for simple/uncomplicated corneal ulceration?
E-collar
Broad-spec topical ABs (NPB, NP-Gramicidin, Erythromycin, Terramycin)
Atropine (until pupil stays dilated)
What is the first step in treating an indolent ulcer? What purpose does this serve?
Debridement
(First w/cotton swab, followed by either 1. Anterior stromal puncture 2. Grid keratotomy or 3. Diamond burr debridement)
To reset the relationship between the epithelium and stroma
What are the 3 potential causes for complex/complicated ulcers?
FHV-1 (cats only)
Early bacterial infection
Early fungal infection
T/F: Diamond burr debridement (DBD) is the best choice to treat cats with corneal ulceration.
FALSE, never perform ASP, GK, or DBD on cats - often causes sequestrum
What are the 3 most common bacteria that cause corneal infection?
Staphylococcus (gr +, aerobic cocci)
Streptococcus (gr+, aerobic cocci)
Pseudomonas aeruginosa (gr -, facultative anaerobic rod)- causes melting
What is this?
Descemetocele
What are the 4 reasons why we see more descemetoceles relative to any other type of deep corneal ulcer?
- Loss of epithelium (trauma, FHV-1, eyelid abnormalities…)
- Breaches defense and susceptibility to infection
- Stoma is extremely sensitive to proteases from bacteria/fungi/neutrophils
- Progression of collagenolysis through the stroma is rapid (<24h)
Which 2 of these diagnostics are NOT indicated/necessary to diagnsose a deep/stomal ulcers?
STT
Fluoroscein
Topical anesthesia
Cytology
Aerobic culture
Tonometry
STT - less imporant in the affected eye, more important in the normal eye
Tonometry - avoid in fragile eyes
What are the 3 indications for parenteral antibiotics when a deep ulcer is present?
- The ulcer has become vascularized
- Cornea is close to perforation or has perforated
- Iatrogenic vascularization (e.g. Flap surgery)
What are the 3 options for anti-collagenase therapy?
- Autologenous (or equine) serum
- 1% EDTA solution
- 10% N-acetylcysteine
What are the 3 guidelines for referral or surgical repair of a deep ulcer?
- Ulcer has 50% or greater stomal depth
- Ulcer is failing aggressive medical therapy
- Descemetocele or perforation
What procedure has been done here and what purpose did it serve? What is a disadvantage of this surgery?
Conjunctival pedicle flap
To provide immediate tectonic strength, provide blood supply for parenteral AB tx, provides serum for anti-collagenolysis
Disadvantage: Can cover the visual axis (i.e. blindness)
What is going on here?
Pannus aka Chronic Superfcial Keratitis
Note raised granulation tissue and pigment
What features indicate simple vs complex superficial ulcers between the eye in 1 and the eye in 2?
- Simple/uncomplicated: No evidence that ulcer is indolent, has an underlying irritant, or is infected
- Complicated: Early bacterial infection; early episcleral injection, severe edema, deep vessels
Given that neither of these ulcers have healed within the expected time frame, what features indicate which variation of complex ulcer is present in eye 1 and eye 2?
- Superficial vessels, stain seen under epithelial edge, loose epithelium with folding = Indolent (Debridement indicated)
- Moderate episcleral injection, turbid anterior chamber (flare), diffuse corneal edema, marked miosis, stain seen under epithelial edge = Early bacterial infection (Do not do ASP, GK, or DBD)
What are the most common clinical signs associated with uveitis?
Aqueous flare
Keratic precipitates
Ciliary flush
Fibrin development
Hypopyon
Hyphema
(Hypotony (decr IOP) = acute uveitis)
What is a diagnostic plan for uveitis?
MDB: history, exam, CBC/chem, UA, rads, 4Dx (or if cat FIV/FeLV and Toxo), fungal titer
(If hyphema present: BP, PTL count, coag panel)
What is the treatment plan for uveitis?
Topical corticosteroids (unless has ulcers)
Topical NSAIDs (unless has ulcers)
Systemic corticosteroids (if vision loss imminent due to inflammation of nerve)
Mydriatics (Atropine)
What are the 3 components of the uvea?
Iris
Ciliary body
Choroid
(Uvea= Greek for grape)
What defines uveitis?
Breakdown/inflammation of the blood-occular barrier
Inflammation of the iris and ciliary body is termed _____ uveitis or ________. Inflammation of the choroid is termed ______uveitis, which usually occurs with retinal inflammation and is thus termed ________. Inflammation of the whole uvea is termed ______.
Anterior
Iridocyclitis
Posterior
Chorioretinitis
Panuveitis
What is the pathopnomic sign of anterior uveitis in which proteins and cells are suspended in the anterior chamber? What does its presence signal?
Aqueous flare
Active inflammation
What is the pathognomic sign for uveitis referring to 360deg deep corneal neovascularization? The vessels arise from the ciliary body and deep episcleral vessels.
Ciliary flush
What pathognomic sign of uveitis is often responsible for synechia?
Fibrin
What is the settling down of WBCs dependenly in the anteior chamber called?
Hypopyon
What causes the iris to bulge forward like a donut? What is this called?
360deg posterior synechia
Iris bombe
What is hyphema and what does it indicate?
Blood settling in the anterior chamber
Indicative of large breakdown in the blood ocular barrier
(can be caused by uveitis, hypertension and coagulopathies)
What does atropine induce which is useful in alleviating pain from uveitis due to ciliary body spasm?
Paralysis of the ciliary body
What is the vascular layer of the eye?
Uvea
What are the 2 components of the blood ocular barrier?
- Blood-aqueous barrier
- Blood-retinal barrier
Inflammation during uveitis is driven by prostaglandins. What else are prostaglandins responsible for (name 3 things)?
Miosis
Decreased IOP
Iris hyperpigmentation
What is the Tyndall Effect?
Proteins and cells which leak into the anterior chamber (aqueous flare) causing light to scatter through a turbid environment
What is normal IOP?
10-20 mmHg
What are some common sequelae to chronic uveitis?
Cataracts
Secondary lens luxation- cats
Secondary glaucoma
Retinal detachment
Phthisis bulbi
What is the most common cause of blindness from uveitits?
Secondary glaucoma
What are the 2 categories of the causes of canine uveitis?
Exogenous (e.g. trauma, reflex uveitis)
Endogenous (e.g. lens-induced, infection, neoplasia, metabolic, auto-immune)
What is the most common primary canine uveal neoplasm? What is the most common DDx for this mass?
Melanocytoma
Uveal cyst (= free floating, use retroillumination or see if it floats to ddx)
What causes “Roman nose” and granulomatous chorioretinitis?
Cryptococcosis
What is the most common feline uveal tumor? What are the 4 criterion that can assist in diagnosis?
Diffuse Iris Melanoma
- Rapid progression (weeks-months)
- Texture is ‘velvety’
- Dyscoria due to invasion of the musclature
- Pigmented cells floating in anterior chamber
* Only histopath (enucleation) can confirm diagnosis*
What drugs do all cases of uveitis need?
Anti-inflammatories
