Cognition & Senses 2: Cornea Flashcards
name RED & BLACK circles?
what’s BETWEEN them?
RED = LENS
BLACK = CORNEA
BETWEEN = ANTERIOR CHAMBER filled with AQUEOUS HUMOR
what is the FUNCTION of the cornea? (2)
- REFRACT LIGHT = capture IMAGE on the RETINA & send it to the BRAIN via OPTIC NERVE
- BARRIER to MICROORGANISMS
the CORNEA is MOSTLY MADE OF ____ ARRANGED ____
blood vessels?
how THICK is it?
REGULARLY ARRANGED COLLAGEN
MOSTLY AVASCULAR
it’s ~0.65 mm THICK
what NOURISHES the CORNEA?
nourishment = PRE-CORNEAL TEAR FILM & LIPIDS
what makes the cornea TRANSPARENT? (two)
- REGULARLY ARRANGED COLLAGEN with NO BLOOD VESSELS
- MOST DEHYDRATED STRUCTURE in body, so LIQUID FROM TEARS/AQUEOUS HUMOR PASSIVELY FLOWING IN will be PUMPED OUT BY Na/K pumps on the CORNEAL ENDOTHELIAL LAYER
what happens if the Na/K ENDOTHELIAL pump in the CORNEA is DYSFUNCTIONAL?
FLUID OVERLOAD & CORNEAL EDEMA
ID what LESION this is & WHY
CORNEAL EDEMA
why? = the PUPIL & IRIS ARE OBSCURED, so we cannot see anything else, meaning that SOMETHING HAS COMPROMISED THE CORNEAL ENDOTHELIUM or EPITHELIUM
ID LESION & WHY
KERATITIS
why? = this is a result of BLOOD VESSELS & INFLAMMATORY INFILTRATES
ID LESION & LOCATION
what does it tell you in the DOG?
CORNEAL PIGMENT in the ANTERIOR CHAMBER
in the DOG, tells you CHRONIC CORNEAL INFLAMAMTION
ID LESION
tends to be present in ___-STAGE _____ DZ
CORNEAL MINERALIZATION (from LIPID or Ca)
tends to be present in END-STAGE CUSHING’S DZ
CORNEAL ENDOTHELIAL DECOMPENSATION…
= definition
3 appearance traits for eye?
= the CORNEAL ENDOTHELIAL CELLS DO NOT WORK, causing the Na/K PUMP to NOT WORK, causing DIFFUSE CORNEAL EDEMA
appearance?
1. DIFFUSE CORNEAL EDEMA ‘BLUE’
2. COBBLESTONE APPERANCE
3. CORNEAL THICKENING
ID DZ (3 words)
how can you tell what caused this?
CORNEAL ENDOTHELIAL DECOMPENSATION
AGE-RELATED CORNEAL DZ if it’s BLUE EYES that are BILATERALLY SYMMETRICAL
CAUSES of CORNEAL ENDOTHELIAL DZ…
primary? (2)
–>which one is MOST COMMON?
–> which one occurs in MIDDLE-AGED animals?
secondary? (1)
–> & give 2 examples
primary?
1. most commonly AGE-RELATED DEGENERATION of ENDOTHELIUM
- CORNEAL ENDOTHELIAL DYSTROPHY based on BREED, occurs in MIDDLE-AGED animals
secondary? = INTRAOCULAR DZ –> ex = uveitis or glaucoma
ID DZ
BILATERAL UVEITIS
AGE-RELATED ENDOTHELIAL DEGENERATION…
= occurs when…
onset?
painful?
unilateral vs. bilateral? why?
= occurs when ENDOTHELIAL CELL DENSITY DECREASES with AGE
usually SLOWLY PROGRESSIVE
often DOESN’T BECOME PAINFUL UNTIL LATE STAGES
ALWAYS BILATERAL because CORNEAL ENDOTHELIAL CELLS ARE THE SAME AGE IN BOTH EYES
CORNEAL ENDOTHELIAL DYSTROPHY…
= what is it?
3 predisposed breeds?
unilateral vs. bilateral? severity?
diagnosis? (three)
= IMPAIRED, ABNORMAL DEVELOPMENT of the CORNEA
3 breeds?
1. BOSTON
2. CHIHUAHUA
3. DACHSHUND
if YOUNGER ONSET, then UNILATERAL and EVENTUALLY BILATERAL —> ASYMMETRICAL SEVERITY IS COMMON
diagnosis?
1. CLINICAL SIGNS
–> DIFFUSE CORNEA that’s BLUE & THICKENED
- SIGNALMENT (breed?)
- RULE OUT UNDERLYING DZ (UVEITIS & GLAUCOMA)
ID DZ
CORNEAL ENDOTHELIAL DYSTROPHY
BULLOUS KERATOPATHY…
= definition
what 3 things can happen to the patient’s eyes as a result?
= when CORNEAL EDEMA is CHRONIC, and eventually forms BLISTERS or BULLA on the SURFACE OF THE EYE (cornea)
3 things…
1. the BULLA/blisters can RUPTURE & cause CORNEAL ULCERS
2. OCULAR PAIN
3. VISION IMPAIRMENT
ID DZ
ADVANCED, CHRONIC CORNEAL EDEMA causing BULLOUS KERATOPATHY
TREATMENT for CORNEAL EDEMA…
depends on…
we usually ONLY TREAT when…
medical tx? (1) how often?
depends on UNDERLYING DZ
we usually only treat when the edema is…
1. MARKED
2. or there’s PROGRESSIVE BULLA
medical tx?
= put MURO 128 (salt solution) on CORNEAL EPITHELIUM to PULL FLUID OUT OF THE EYE to REDUCE BLISTERS
–> BID to TID
RHO-KINASE INHIBITORS…
used normally for WHAT in people?
what can they do in dogs?
why is this not CLINICALLY very useful?
used normally to treat GLAUCOMA in people
in DOGS, can REPAIR or ENCOURAGE CORNEAL EPITHELIAL CELLS to IMPROVE FUNCTION in response to CORNEAL EDEMA
not very useful because only causes TRANSIENT relief
SURGICAL tx for CORNEAL EDEMA? (2)
prognosis?
helps to control ____ but DOES NOT help….
SURGICAL tx?
1. THERMOKERATOPLASTY = makes BURNS in cornea and TRIES TO ELIMINATE ULCERS
- GUNDERSEN FLAP = with a blade, remove ANTERIOR STROMA and CREATE A THIN MEMBRANE OF CONJUNCTIVA via a GRAFT to PULL OVER CORNEA
prognosis = GUARDED
helps to control PAIN but DOES NOT HELP VISION as TRANSPARENCY IS LOST
KERATITIS…
= definition
2 sub-categories?
what is a HALLMARK of this DZ?
–> is this always seen?
= CORNEAL INFLAMMATION
2 subs?
1. ULCERATIVE
2. NON-ULCERATIVE
VASCULARIZATION is a HALLMARK OF CORNEAL INFLAMMATION
–> NOT always seen GROSSLY bc vessels can be DEEP
DURATION & LESION?
CHRONIC KERATITIS
DURATION & LESION?
ACUTE KERATITIS
CORNEAL ULCER…
aka?
= definition?
commonality?
aka ULCERATIVE KERATITIS
= LOSS of CORNEAL EPITHELIUM +/- STROMA
common in DOGS & CATS
ID LESION & potential DISEASE that caused it
LESION = CORNEAL ULCER (ulcerative keratitis)
DZ = FHV-1 can cause this SPONTANEOUSLY
how can you tell if a corneal ulcer is SUPERFICIAL or DEEP?
SUPERFICIAL = ulcer is SMOOTH
DEEP = ulcer is INDENTED
CAUSES of CORNEAL ULCERS…
- EXTERNAL TRAUMA
- TEAR FILM ABNORMALITIES
- NEURON DAMAGE to CORNEA (CN V, OPHTHALMIC BRANCH)
- INFECTION
- EYELID DZ
what NEURON INNERVATES the CORNEA?
CN V, OPHTHALMIC BRANCH of TRIGEMINAL NERVE
CLINICAL SIGNS of CORNEAL ULCERS… (list five)
- PAIN –> have EXPOSED CN V NERVE ENDINGS from REMOVED EPITHELIUM
- INFLAMMATION
- OCULAR DISCHARGE
- EDEMA
- STROMAL LOSS ‘DIVOT’
IRIDOCYCLOSPASM…
= definition
causes WHAT 2 things?
usually secondary to WHAT?
= when NERVE ENDINGS of CN V are AGITATED, causes SPASM of CILIARY BODY MUSCLE & IRIS MUSCLE
causes…
1. PUPIL TO GET SMALL
2. OVERALL PAIN
usually secondary to CORNEAL ULCER
ID LESION
CORNEAL ULCER
also can see CORNEAL EDEMA & INFLAMMATION
if we can SEE BLOOD VESSELS in the eye with a CORNEAL ULCER, what does this indicate?
indicates that the ulcer is LIKELY CHRONIC
DESCEMETOCELE..
= definition
what does this indicate?
= if a CORNEAL ULCER is DEEP ENOUGH, then HOLE IN THE CORNEA will be DEEP ENOUGH TO BASEMENT MEMBRANE or DESCEMET’S MEMBRANE
this indicates that you’re MINUTES AWAY FROM CORNEAL PERFORATION
ID LESION
what does this mean??
DESCEMETOCELE
this means THE CORNEA IS ABOUT TO PERFORATE!
once CORNEAL EPITHELIUM is DAMAGED, what disease is possible/how does it occur?
what does the cornea LOOK LIKE?
what are 2 common etiologic agents?
BACTERIAL INFECTION can occur when they COLONIZE ON STROMA prior to the EPITHELIUM HEALING
CORNEA can look SOFT & MELTED
2 common agents? = SKIN FLORA
1. STREP
2. STAPH
ID DZ
CORNEAL INFECTION
DIAGNOSIS of CORNEAL ULCER?
how does it work?
what DZ would NOT STAIN even though it’s a problem?
via POSITIVE FLUORESCIN DYE STAIN
the CORNEAL STROMA will TAKE UP THE DYE because the STROMA is HYDROPHILIC, while if EPITHELIUM was intact it’d be HYDROPHOBIC (not take up any stain)
a DESCEMETOCELE will NOT STAIN bc THE DESCEMET’S MEMBRANE IS ALSO HYDROPHOBIC
TREATMENT for CORNEAL ULCERS…
depends on what 3 things?
SUPERFICIAL ulcers (5)?
DEEP ulcer treatment depends on… (3)
depends on…
1. DEPTH of the ULCER
2. INFECTION presence or not
3. APPROPRIATE HEALING RESPONSE from the cornea
SUPERFICIAL ulcers?
1. give E-COLLAR
- generally heal RAPIDLY by EPITHELIALIZATION in 5-7 DAYS
- BROAD-SPECTRUM ANTIBIOTICS to PREVENT INFECTION TID
- TOPICAL ATROPINE for PAIN
- RECHECK in 1-WEEK
DEEP ulcers tx depends on..
1. treatment DEPENDS on HOW FAR AWAY THE NEWLY CREATED BLOOD VESSELS ARE from the ULCER (grows 1 mm/DAY)
- CORNEAL INTEGRITY is COMPROMISED or not
- INFECTION PRESENT
ATROPINE…
why is it an IRIDOCYCLOPLEGIC drug?
what will the PUPILS do?
how does it work?
IRIDOCYCLOPLEGIC = stops the SPASMING of the CILIARY BODY, which is associated with IRITOCYCLOSPASM
will cause the PUPILS TO DILATE
how does it work? = PREVENTS spasm of ciliary body muscle & pupil muscle and STOPS PAIN
how should we ADMINISTER CORTICOSTEROIDS or NSAIDs for CORNEAL ULCERS?
why? (2)
we should administer CORTICOSTEROIDS or NSAIDs ORALLY
why? because if we do TOPICAL…
1. it can DELAY CORNEAL HEALING
- and PREVENT COLLAGENASE ACTIVITY
INDOLENT CORNEAL ULCER…
= definition
etiology?
commonality?
2 signalments?
2 clinical signs in EYE? (1 is +/-)
= SUPERFICIAL CORNEAL ULCER which FAILS TO HEAL IN APPROPRIATE TIME
etiology? = usually due to UNDERLYING CORNEAL DEFECT with the BASEMENT MEMBRANE
commonality? = COMMON IN DOGS
2 signalments?
1. GERIATRIC DOGS
2. BOXER BREEDS
clinical signs in EYE?
1. VISIBLE LIPS of COREAL EPITHELIUM from it SLOUGHING OFF (lighter stain)
2. +/- BLOOD VESSELS in CORNEA
how do CORNEAL ULCERS usually heal?
need VASCULARIZATION & COLLAGEN DEPOSITION done by COLLAGENASES, which are produced by CORNEAL EPITHELIAL CELLS & NEUTROPHILS
TREATMENT for INDOLENT CORNEAL ULCER (SUPERFICIAL)?
what is the TIME RANGE in which this should work?
what TOOL do we usually use?
prognosis?
if this DOES NOT WORK, then do what?
tx = CORNEAL DEBRIDEMENT to REMOVE LOOSE EPITHELIAL EDGES & promote EPITHELIALIZATION/VASCULARIZATION
this should work in 7-10 DAYS
tool? = DIAMOND BURR
prognosis = GENERALLY GOOD, MAJORITY HEAL
if this DOES NOT WORK, then a BANDAGE CONTACT LENS can help KEEP EPITHELIUM ADHERED TO EYE & PROMOTE HEALING, but can also cause scarring
if we suspect an INFECTED CORNEAL ULCER, what DIAGNOSTIC should we do?
what tx/frequency for SEVERE cases?
DIAGNOSTIC = C&S for ANTIBIOTIC PRESCRIPTION
tx = FLUOROQUINOLONES if UNSURE ABOUT SAFETY OF PERFORMING CULTURE, can give EVERY 2 HOURS FOR SEVERE CASES
MAIN MEDICAL TREATMENT for CORNEAL ULCERS?
–> what does it do?
if NOT IMPROVING/GETTING WORSE after 48 hours, what should we consider?
MAIN MED = ANTI-COLLAGENASE, has SERUM that has NATURAL ANTIPROTEASE/ANTICOLLAGENASES to PREVENT CORNEA MELTING from ulcer
if NOT IMPROVING or GETTING WORSE after 48 hours = SURGERY
SURGICAL REPAIR for CORNEAL ULCERS…
usually done using ___ ____
3 steps?
1 advantage?
1 disadvantage?
we DO NOT perform this surgery UNLESS we believe…
usually done using CONJUNCTIVAL GRAFTS
steps?
1. make LIP OF CORNEA
2. move it OFF SCLERA
3. flap up CONJUNCTIVAL GRAFT to MAKE A SEAL
advantage = BRING BLOOD SUPPLY DIRECTLY TO AREA to cause HEALING and THICKENING OF CORNEA
disadvantage = DECREASES TRANSPARENCY of CORNEA
we DO NOT perform this surgery UNLESS we believe that WE CAN PRESERVE THE ANIMAL’S VISION
PANNUS
aka? (3 words)
common in WHAT BREED?
what ENVIRONMENTAL FACTOR makes it WORSE?
pain?
what do we see on a FLUORESCIN STAIN?
aka CHRONIC SUPERFICIAL KERATITIS
common in GSD
exposure to UV LIGHT MAKES IT WORSE
usually starts as NON-PAINFUL
on FLUORESCIN STAIN, DOES NOT TAKE UP DYE
ID LESION (2 names)
note: this lesion DID NOT TAKE UP FLUORESCIN STAIN
LESION = CHRONIC SUPERFICIAL KERATITIS or PANNUS
ID LESION (2 names)
PANNUS or CHRONIC SUPERFICIAL KERATITIS
ID LEFT AND RIGHT BUBBLE
LEFT = PANNUS or CHRONIC SUPERFICIAL KERATITIS
RIGHT = PLASMOMA from ACCUMULATION OF PLASMA CELLS in CORNER OF EYE
3 STRONG SIGNS for PANNUS?
- VENTROLATERAL PROGRESSIVE signs
- BREED PREDILECTION (GSD)
- NO FLUORESCIN DYE TAKE-UP
TREATMENT for PANNUS? medication & duration?
frequency?
mostly TOPICAL CORTICOSTEROIDS like CALCINEURIN INHIBITORS for 4-6 WEEKS
frequency can be up to 4 times DAILY initially, then try to reduce to TWICE DAILY
PROGNOSIS for PANNUS?
if UNTREATED…
often MANAGED but NOT CURED, so OK
if UNTREATED, can lead to BLINDNESS
PIGMENTARY KERATITIS>..
= definition
2 predisposed breeds? due to ____ _____
treatment options? (3)
= when MELANIN is DEPOSITED INTO CORNEA as a NON-SPECIFIC RESPONSE to CHRONIC, NON-ULCERATIVE CORNEAL INFLAMMATION
2 predisposed breeds? due to POOR CONFORMATION
1. PUGS
2. PEKINGESE
treatment?
1. OCULAR LUBRICATION
2. CLOSE DOWN MEDIAL CANTHUS (to stop lagophthalmos)
3. TACROLIMUS
CORNEAL MINERALIZATION…
= definition
usually NON-____
DOGS vs. CATS?
MOST COMMON presentation?–> how does it look?
–> etiology?
–> pain/tx?
= LIPID or CALCIUM DEPOSITION in CORNEA
usually NON-ULCERATIVE
DOGS > CATS
most COMMON = CORNEAL DYSTROPHY
–> milky WHITE, BILATERAL
–> CONGENITAL
–> NO PAIN/TX
ID LESION
CORNEAL MINERALIZATION
TRUE/FALSE
CORNEAL DYSTROPHY causes an IRREVERSIBLE CHANGE to the cornea
TRUE
CORNEAL LIPIDOSIS..
appearance? (two)
2 causes?
usually NON-___
reversible?
appearance?
1. WHITE, CRYSTALLINE LOOK
2. can be DIFFUSE or UNILATERAL
causes?
1. TOPICAL CORTICOSTEROIDS
2. SYSTEMIC DZ
usually NON-PAINFUL
THIS IS REVERSIBLE
CORNEAL DEGENERATION…
= definition
potential signalment?
appearance?
tx? (3)
= result of CHRONIC CORNEAL DISEASE/ULCER, so even if it’s FINISHED HEALING it DEPOSITS CALCIUM
can potentially also be the result of GERIATRIC DOGS
appearance = HAPHAZARD, WHITE CRYSTALLINE CHANGE
tx?
1. TOPICAL LUBRICATION
2. TREAT CORNEAL ULCERS IF THEY OCCUR
3. use DIAMOND BURR to BREAK DOWN MINERALIZATION
if you see BLOOD VESSELS/INFLAMMATION with CORNEAL MINERALIZATION what medication SHOULD WE NOT USE/WHY?
we SHOULD NOT USE ANTI-INFLAMMATORIES because CALCIUM or LIPID will be MORE LIKELY TO SLOUGH OUT OF CORNEA
how does FELINE HERPESVIRUS cause CORNEAL ___?
how LONG does it take for these to heal?
ULCERS
the virus will LYSE CORNEAL EPITHELIAL CELLS & cause SUPERFICIAL CORNEAL ULCERS
these ulcers can take MONTHS to heal
ID LESION & potential DZ
LESION = SUPERFICIAL CORNEAL ULCER
DZ = FHV-1
TRUE/FALSE
we can treat INDOLENT CORNEAL ULCER in the SAME WAY in a DOG and a CAT
FALSE, CATS need to have FHV-1 TREATED PRIMARILY, and CANNOT USE OTHER METHODS
2 CLINICAL SIGNS of FHV-1 in the CORNEA
- DENDRITIC ULCERS in the CORNEA (breaks in epithelium)
- GEOGRAPHIC/NON-HEALING ulcer
ID LESION & DZ
DENDRITIC CORNEAL ULCER
likely FHV-1
STROMAL DZ..
= definition
often caused by WHAT?
treatment?
–> MOSTLY?
& 2 more!
PROGNOSIS focuses on ____ rather than ____
= NON-ULCERATIVE KERATITIS that causes SCARRING, PAIN & IMMUNE-SUPPRESSION
often caused by OCULAR FHV-1
treatment?
–> MOSTLY supportive care!
1. TETRACYCLINE ANTIBIOTICS
2. ARTIFICIAL TEARS
PROGNOSIS focuses on MANAGEMENT rather than CURE
ID DZ
what should we expect on CYTOLOGY that’s DIAGNOSTIC?
painful?
treatment? & duration? (2)
EOSINOPHILIC KERATITIS
on CYTOLOGY, expect to see EOSINOPHILS, and EVEN ONE IS DIAGNOSTIC!
USUALLY NOT PAINFUL
treatment?
1. TOPICAL ANTIVIRALS usually LIFELONG
2. CORTICOSTEROIDS shorter term
CORNEAL SEQUESTRUM…
= how does this occur IATROGENICALLY?
give a breed PREDISPOSITION? (3 & overall)
IATROGENIC = if you DIAMOND BURR or DEBRIDE A CAT TOO VIOLENTLY with a NON-HEALING CORNEAL ULCER, causing a REGION OF NECROSIS
breeds?
1. BRITISH SHORTHAIRS
2. BURMESE
3. PERSIANS
–> overall, CATS WITH LAGOPHTHALMOS causing CHRONIC INFLAMMATION & NON-HEALING ULCERS
ID LESION
CORNEAL SEQUESTRUM
