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The Cornea: 0.5mm is all you get

David A. Wilkie DVM, MS, Diplomate ACVOProfessor Emeritus

The Ohio State UniversityWilkie.1@osu.edu

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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Getting Old?

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