SA Corneal Ulcers
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Transcript of SA Corneal Ulcers
Keeping the Windshield Clean!
Corneal Ulceration: Diagnosis
and Aggressive Treatment
University of Florida
Different ulcer types/depths
Making the diagnosis of a corneal ulcer is
critical for the welfare of the patient.
It is the difference between sight and
blindness, or a small scar and a large scar.
Assume ulcers will get worse!
Treat aggressively.
The dog cornea is 0.55 mm thick centrally and 0.65 mm thick peripherally.
The cat cornea is about 0.58 mm thick centrally and peripherally.
The superficial cornea is most sensitive.
The tear film gives a smooth optical surface.
Most of the stroma is collagen.
The endothelium contains a pump.
The corneal stroma is 90% of the corneal thickness. – parallel bundles of collagen fibrils
– keratocytes and GAGs.
Corneal sensitivity is reduced – brachycephalic dog and cat breeds
– diabetic dogs: 28% lower STT; 37% lower corneal sensation; 58% shorter TFBUT not related to degree of control or duration
Nerves
Corneal epithelium is a barrier against bacteria.
In simple traumatic corneal injuries in which a small
amount of epithelium is removed, healing is rapid.
If the ulcer becomes infected or the epithelium is
unable to attach to the stroma, healing is delayed,
and progression to a deep stromal ulcer may
occur.
WBCs can help too much!! NE and MMPs.
In infected ulcers, tear proteases digest
stromal collagen to cause a descemetocele,
and iris prolapse (within 24 hrs).
Proteases (MMP and NE) are produced by
keratocytes, tear film PMNs and microbes.
“Melting”
??
Corneal degeneration due to
proteases is referred to as
"melting".
Ulcers in which proteases are
active have a grayish-gelatinous
appearance
Distinguish melting from
corneal edema.
Topical corticosteroids increase
tear protease activity.
MMP-9 increased in dog ulcers Melting and necrosis
A corneal ulcer is a lesion
in which the corneal
epithelium and a variable
amount of corneal stroma
have been lost.
Cobalt blue filters aid
diagnosis.
Ulcers can be classified by depth:
– a. Superficial ulceration
Epithelial erosions/abrasions
Recurrent "Boxer Ulcers“
Early herpes ulcers in cats
– b. Deep stromal ulcers
Melting ulcers
Geographic herpes ulcers in cats
– c. Descemetoceles (about to rupture)
– d. Perforating ulcers (Iris prolapse)
Regardless of the initial cause, all ulcers are
associated with some iridocyclitis.
The uveitis may be severe with the potential
to progress to endophthalmitis.
Hypopyon
Ulcers can be classified by
Etiology
A. Mechanical disruption:
Trauma
Foreign bodies
Exposure (anesthesia, CN7 paralysis)
Entropion and trichiasis
Eyelash disease- distichiasis, ectopic cilia
“Boxer” ulcers and nonadherence
B. Infectious: Bacterial, Mycotic, Viral
C. KCS
D. Bullous Keratopathy - Cats
E. Neurotrophic – corneal insensitivity
F. Neuroparalytic - CN7
paralysis
Diagnosis of Corneal Ulceration
a. Clinical signs of ulceration:
1) Pain and blepharospasm
2) Tearing
3) Purulent ocular discharge
4) Miosis due to uveitis
5) Corneal edema/vascularization
b. Culture
c. Schirmer tear test
d. Cytology
e. Fluorescein stain
Descemetoceles do not stain
Initial therapy for an
ulcer depends on
whether:
– the ulcer is infected
– the ulcer is superficial or
deep
– the ulcer is melting
– UVEITIS IS FOUND
WITH EVERY ULCER!
The primary objective of current treatment
strategies for infectious keratitis is to sterilize the
ulcer as rapidly as possible with topically
administered antibiotics.
Kill everything !!
Ulcers can degenerate even if sterile!
Sterility does not guarantee healing!!
MEDICAL TREATMENT OF ULCERS Treat etiology: eg KCS, entropion, infection
Broad-spectrum topical antibiotics
– culture and sensitivity tests can guide selection.
Reduce tear protease activity:
EDTA, Serum, Acetylcysteine
– Serum contains an alpha-2 macroglobulin with
anticollagenase activity.
Treat Uveitis
– Topical atropine: cycloplegia/mydriasis
– Topical NSAIDs?????
No steroids with ulcers. They really do not help!!
Antibiotics commonly used in
ulcers:
– bacitracin, neomycin, polymyxin
– erythromycin
– Tobramycin
– Fusidic acid
– chloramphenicol: static
– gentamicin*
– ciprofloxacin***
– cefazolin (55 mg/ml)***
Antibiotics are Toxins
Effects of in vitro antibiotics on dog corneal epithelial cells:
chloramphenicol < tobramycin < neopolygram < gentamicin
< cefazolin < ciprofloxacin
(Hendrix AJVR 62:1664-1669, 2001)
Horses: Increasing resistance of Streptococcus to
gentamicin, and Pseudomonas to gentamicin and
tobramycin.
– Pseudomonas: 20% resistant to gentamicin and tobramycin in
92-98 and 55% resistant at present.
– Ciloxan is still good for Pseudomonas.
No pattern like this seen in dogs.
“Melting”: gray, mucoid,
gelatinous cornea
– autogenous serum: Serum
inhibition lasts 8 days!!
Alpha 2 macroglobulins
NE and MMP inhibition
– 0.17% ETDA (MMP)
– 5% acetylcysteine (MMP)
RB positive
– topical 0.025% doxycycline (MMP)
Combinations of antiproteases
Treatment reduces MMP by ~80%
after 4-7 days.
Antiproteases
Inhibition of MMP-2 & MMP-9 is most important
in dogs, cats and horses
The significance of the serine proteases is under
investigation
Serum
– α2-macroglobulin = protease inhibitor that entraps
both main classes of proteases
– α1-PI (serine protease inhibitor )
Combining antibiotic therapy with MMP
inhibitors can speed corneal healing as MMP play
an important role in corneal ulceration and
stromal liquefaction.
Every animal with a corneal ulcer
has anterior uveitis
Hypopyon
Fibrin
Topical NSAIDS for ophthalmic
use
– Flurbiprofen (Ocufen)
– Suprofen (Profenal)
– Diclofenac (Voltaren)
– Can be used to decrease signs of uveitis
in the presence of a corneal ulcer BUT
DON’T!
Superficial Ulcers with Minimal Corneal Tissue Loss
– Triple antibiotic or tobramycin QID
– 1% atropine SID or BID till pupil is dilated- May not send home.
– Serum QID
– recheck the next day to evaluate for “melting”
Eyes with ulcers should show reduced
fluorescein uptake and the eye be less
painful in 24-48 hours, unless……...
Melting ulcers should show an increase in
stromal rigidity in the first 24 hours. If not,
surgery is indicated as corneal rupture is
possible.
Healing of a corneal ulcer
will be observed as a 360°
clearing of the cornea,
beginning at the limbus.
If the cornea is healing,
the stimulus for the
uveitis should be reduced
– the pupil will stay dilated
easier
– The frequency of atropine
therapy can be reduced.
Ulcers with Melting or
Keratomalacia: Therapy
– Ulcers infected or sterile
– Very aggressive medical
and/or surgical therapy
– Tobramycin, gentamicin or
cefazolin q2h
– Natamycin if + for hyphae
q4h
– Atropine q4h till dilated
– Serum and EDTA q1h
– Systemic NSAIDS BID
– Keratectomy and CF
PMNs are stimulated by
epithelial cell cytokines to
release serine and matrix
metalloproteases to cause
“melting”.
– Topical Serum is very
beneficial for melting ulcers.
It inhibits serine proteases
and MMPs.
– Topical EDTA (0.17%) and
acetylcysteine (5%) inhibit
MMPs.
– Ilomostat
– Topical 0.1% doxycycline
Combined
antibiotic/protease
inhibitor therapy might
improve clinical results.
Ulceration often continues
due to the continued
presence of tear proteases
in spite of ulcer
sterilization with effective
antibiotic treatment.
SURGICAL TREATMENT OF ULCERS
Conjunctival flap autografts are
used for the clinical management
of:
– deep and large corneal ulcers
– stromal abscesses
– descemetoceles
– perforated corneal ulcers with
and without iris prolapse.
Tarsorrhaphies and TE flaps
Deep Ulcers, Descemetoceles
and IP
Types of conjunctival flaps (CF)
CF surgery requires
general anesthesia.
Pedicle flaps allow
monitoring of the anterior
chamber
– Leave in place for 4-6 wks.
– Most CFs require a
temporary tarsorrhaphy.
Conjunctival
flap/Tarsorrhaphy
DESCEMETOCELES
– 14 microns!!
Look at the flash??
??
Amnion Membrane Transplants
“Dixie” Stacy
2
Iris Prolapse
a) Emergency
b) Systemic antibiotics
c) General anesthesia and
surgical repair of cornea
d) Topical antibiotic solutions,
not ointments. Topical
atropine
e) Reposition or amputate
protruding iris; suture cornea
(7-0 suture); reform AC with
LRS
f) CF if needed
CORNEAL LACERATIONS
Management depends on depth of laceration.
Superficial lacerations (stain with FL). Treat as simple ulcer - topical antibiotics and atropine
Deep, non-perforating lacerations. Topical antibiotics, serum and atropine
– Less than 1/2 thickness: CF or treat as ulcer
– More than 1/2 thickness: suture cornea
Herpes keratitis
Cats
Dendritic ulcers of the
cornea and conjunctiva
Topical acyclovir or
idoxuridine QID
Oral lysine 500 mg BID
– Viralys Vet
Oral interferon: 300 U/day
Geographic herpes ulcer
REFRACTORY SUPERFICIAL
CORNEAL EROSIONS
"Indolent Ulcer” or
"Boxer Ulcer"
Middle to old age, increased
incidence in females
Breed predilection: Boxer,
Corgi, Pekes, Lhasa Apso
Clinical Signs:
Superficial corneal erosion with epithelial "lips" (Epithelium rolled up and back at edges)
Chronic blepharospasm, epiphora, and photophobia
Lesions usually unilateral
Fluorescein diffuses under epithelium
The cause is a defect in the hemidesmosomes
of the basal corneal epithelial cells.
The basal corneal epithelium may not be
producing normal basement membrane. A
hyaline membrane forms on the ulcer.
Other Rule-outs for
Nonhealing ulcers
KCS
ectopic cilia
foreign bodies
entropion
infection
Ectopic Cilia
Treatment of “boxer ulcers”
Remove abnormal epithelium by debridement with topical anesthesia and cotton-tipped applicator
may need numerous debridements
“the lip”
Grid Keratotomy for superficial ulcers only! 20 gauge needle.
Not for cats!!
“Scratchers”
MULTIPLE PUNCTATE KERATOTOMY
“Pokers”
20 g bent needle
scars
Needle guard
or bend the tip
Medical treatment of “boxer ulcers”
Topical antibiotic solutions.
– Do not use gentamicin or ciprofloxacin!!
– No steroids!!
Topical 1% atropine as needed
Topical hyperosmotics (5% NaCl)
Use Elizabethan collars to help prevent self trauma
Adequan (100 mg/ml) for topical use: – 50 mg/ml in PVA artificial tears (Tears Naturale)
Growth factors in serum may be beneficial in persistent erosions. EGF??
Hylashield (Hylan) topically
Soft contacts and collagen shields
Chemical cautery (Lugol’s iodide, TCA, phenol)
Superficial keratectomy
Tarsorrhaphies and TE Flaps
Corneal Foreign Bodies
Day 7
Day 1
FB
Penetrating Keratoplasty (PK)
Deep corneal ulcers
Descemetoceles
Endothelial dystrophy
PK in a dog for endothelial dystrophy