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The Cornea: 0.5mm is all you get
David A. Wilkie DVM, MS, Diplomate ACVOProfessor Emeritus
The Ohio State [email protected]
0.5-0.6 mm
Cornea Epitheliumn 8-15 cell layers thick
7 day turnover
Diagnostic tests for corneal abnormalities
n Examinationn Finoffn Biomicroscopy
n Culturen Schirmer tear testn Fluorescein dyen Cytology
Diagnostic tests for corneal abnormalities
n Examinationn Finoff
Diagnostic tests for corneal abnormalities
n Examinationn Finoffn Biomicroscopy
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You have many choices in loupes
Loupes
You get what you pay for
Recommend:Zeiss - $$$KeelerHeine
Bad Choice
Good Choice
Diagnostic tests for corneal abnormalities
n Examinationn Finoffn Biomicroscopy
n Culture
Diagnostic tests for corneal abnormalities
n Examinationn Finoffn Biomicroscopy
n Culturen Cytology
www.microbrush.com
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Cytology and Culture
Diagnostic tests for corneal abnormalities
n Examinationn Finoffn Biomicroscopy
n Culturen Schirmer tear test
Diagnostic tests for corneal abnormalities
n Examinationn Finoffn Biomicroscopy
n Culturen Schirmer tear testn Fluorescein dye
Tear Break-up
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Tear Break-up - Human Abnormal Tear Break-up - Canine
Diagnostic tests for corneal abnormalities
n Examinationn Finoffn Biomicroscopy
n Culturen Schirmer tear testn Fluorescein dyen Cytologyn Biopsy and histopathology
Corneal SCC
Ulcerative Keratitisn Most ulcers are simple and heal in 24-72
hours, often DESPITE what the Veterinarian does
n When they fail to do so:n Did I miss the etiology?n Is it infected?n Have I done a culture/cytology?n What drugs are being used?n Is it time to discuss surgery?
Ulcerative Keratitisn Ascertain the etiology of the lesion.
WHY?
Ulcerative Keratitisn Ascertain the etiology of the lesion.n Examine the eye for:
n eyelid abnormality
Entropion
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Ulcerative Keratitisn Ascertain the etiology of the lesion.n Examine the eye for:
n eyelid abnormality
Trichiasis
Ulcerative Keratitisn Ascertain the etiology of the lesion.n Examine the eye for:
n eyelid abnormalityn abherent hair
Ectopic cilia
Ectopic cilia
Ulcerative Keratitisn Ascertain the etiology of the lesion.n Examine the eye for:
n eyelid abnormalityn abherent hairn foreign body
Corneal foreign bodypenetrating vsperforating
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Ulcerative Keratitisn Ascertain the etiology of the lesion.n Examine the eye for:
n eyelid abnormalityn abherent hairn foreign bodyn tear deficiencyn infectious causes
Ulcerative Keratitisn Complete history
n duration n previous therapy(especially corticosteroids)
Ulcer
ErosionSuperficial
Midstromal
Deep
Descemetocoele
Superficial Corneal Ulcer
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Superficial Corneal Ulcern Generally extremely painful n Heal within 72 hours when the cause has
been removedn If the ulcer has not resolved in 3 to 5 days:
n cause is still presentn ulcer is infectedn indolent ulcer is present
Indolent Ulcer
Failure of attachment
Indolent Ulcer n Hallmark features:
n Superficialn Nonpainful to mildly painfuln Loose or redundent epithelial bordersn Usually middle aged to older dogs n Chronic in naturen Predisposed breeds - boxers
Indolent Ulcer
Indolent Ulcer Debride
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Debride Grid Keratotomy
Debride
Grid Keratotomy
n Algerbrush diamond burr
3.5mm, medium grit tip
Diamond Burr Debridement
Courtesy Dr Enry Garcia, University of Coloradohttps://www.youtube.com/watch?v=W 2ndvDx_1SE
Algerbrush; Alger Equipment Company, Lago Vista, TX, USA
n Outcomen Debridement - 63% healed after single
proceduren 25% healed at 1st postop visit
n GK - 85% healed after single proceduren 75% healed at 1st postop visit
n SK – 100% healed after single proceduren 88% healed at 1st postop visit
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Indolent Ulcer
n Treatment:n Client education is essentialn Remove loose, redundant epitheliumn Gently break the basement membrane with
25g needle (Grid keratotomy)n Diamond burrn Topical tetracycline - 50% reduced time to
heal (oral doxy also works)n Recheck every 7-14 days
Indolent Ulcern Treatment:
n � Contact lens:n 15mm diameter, thin,
soft bandage lensn >8mm base curven Acrivet
n � Antibiotics
Adult cat - herpesn classic dendritic
ulcern no URT signs
Herpes felisn 70% of cats infected with herpes virus
will become carriersn recurrent conjunctivitis/keratitisn stress and immunosuppression will
predispose to recurrencen FeLVn FIVn Other
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Herpes felisn Diagnosis:
n History - previous stress?
Herpes felisn Treatment:
n Antiviral agents topicallynIdoxuridine - Stoxil, HerplexnTrifluorothymidine - Viropticnq2-4 hr
n Cidofovir 0.5%nQ12 hr
Herpes felisn Treatment
n Antivirals - Systemicn Famciclovir
n Variable doses listedn 65 mg/cat divided dailyn New data suggests 40 mg/kg POn 90 mg/kg PO TID
Herpes felisn Treatment:
n L-lysine, 250-500 mg/day PO
Midstromal Corneal Ulcern Managed medicallyn Associated anterior uveitisn Cytologyn Culture/Sensitivity
Midstromal Corneal Ulcern Treatment:
n Topical antibioticsnBroad spectrum, every 2-6 hoursnNeomycin-bacitracin-polymyxinnGentamicin -poor choicenCiprofloxacinnLevofloxacinnGatifloxacin
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Midstromal Corneal Ulcern Treatment:
n 1% Atropinenas needed to dilate the pupil, but
not more than 4x/day
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Midstromal Corneal Ulcern Treatment:
n Surgery if progressiven Desmetocoelen Melting/collagenase ulcern Acute eruptive keratopathy
n feline
Deep/Desmetocele Corneal Ulcer
n Fluorescein negative centrally
Melting Corneal Ulcern Enzymatic
breakdown of the cornea
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Melting Corneal Ulcer n Surgery often indicatedn Debridement of the melting portion
Melting Corneal Ulcer n Treatment:
n As for deep ulcers, but more aggressive
n Antibiotics are administered every 1-2 hoursn Ofloxacinn Levofloxacinn Gatifloxacin
n Anticollagensen Serumn Tetracycline - topical, systemic
n +/- Surgery
Corneal Cross-linking
Riboflavin-photosensitizer
UV-A
Corneal cross-linking
Specialized instruments
Corneal Surgery
Superficial Keratectomyn Thickness of the normal canine cornea is 0.4-
0.7mmn #64 Beaver blade/Desmarres corneal
dissector
Superficial Keratectomy
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Superficial Keratectomy
Lamellar dissection
Superficial Keratectomy
0.12mm Colibri
Avoid tension in this direction
Superficial Keratectomy
http://youtu.be/vB0P3lJmvXU
Graft? Yes or No Feline Sequestrum Keratectomy
https://www.youtube.com/watch?v=JjHx6-TR8d0
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While on the subject of brown corneas..
Vitreous echo-hemorrhage
Posterior scleral rupture
Normal
Preop 5 days
15 days 60 days300 days
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Canine Corneal SCCSCC pre surgery
SCC post surgery plus 5-FU
SCC beta radiation
Conjunctival Pedicle Graft
Dissect dorso-lateral conjunctiva
Conjunctival Pedicle Graft
Keratectomy prepares site
Conjunctival Pedicle Graft
Epithelial to epithelial apposition
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Conjunctival Pedicle Graft
http://youtu.be/qC2Amv5RW-k
Conjunctival Pedicle Graft
http://youtu.be/IRzC3lHRdps
Equine conjunctival pedicle graft -trimming Equine conjunctival pedicle graft -trimming
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Corneal Perforation
Iris prolapse
Corneal-Conjunctival Graft
Corneal-Conjunctival Graft
http://youtu.be/NvwnZhGpK6M
Feline corneo-conjunctivalgraft
1 yr post-op
24 hr post-op
Canine corneo-conjunctival graft Corneal endothelial dystrophy
Treatment-hyperosmotics-conj graft-fresh transplant
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Pre-op
Post-op
Keratectomy with BioSiSt® Graft
Keratectomy with BioSiSt® Graft
Keratectomy with BioSiSt® Graft
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Deep lamellar endothelial keratoplasty Deep Lamellar Keratectomy
Deep Lamellar Keratectomy Deep Lamellar Keratectomy
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Corneal Transplant
Corneal transplant
Corneal transplant
Corneal transplant Corneal transplant
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Corneal transplant
Penetrating Keratoplasty
Penetrating Keratoplasty Penetrating Keratoplasty
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Penetrating Keratoplasty Penetrating Keratoplasty
Pre-op
2yr Post-op
Corneal Trauman Sharp Trauma Blunt Trauma
Cat ClawNon Perforating
Cat ClawPerforating
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MagnificationEpinephrineViscoelastic8-0 to 9-0 sutureMicrosurgical instruments
http://youtu.be/ex8EZVaP2aI
Pre-op
1yr post-op Cat ClawPerforating with Lens capsule tear
Cat ClawPerforating with Iris prolapse
Phacoanaphylaxis
Blunt trauma
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Blunt vs Sharp
So what do you think?Prognosis?
Normal