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“Scratching the Surface”

Corneal Debridement Workshop

Seema Nanda, ODUniversity of Houston College of Optometry

Texas Eye Institute

Texas Optometry Assoc. Meeting Austin, TX

24th February 2018 / 2-HR: 6-7:40 PM

Overview

• Ocular Conditions for Epithelial

Removal of Cornea

• In-office Techniques

Used for: – Epithelial Removal

– Corneal Debridement

• Demonstration &

Hands-on Workshop

Definition of Debridement

• DEBRIDEMENT <medical term>

– Debride: \di-ˈbrēd, dā-\ transitive verb

– Surgical removal of:

• Lacerated

• Devitalized or

• Contaminated

tissue

Ocular Conditions

• For Epithelial removal:

– PRK: Photo-Refractive Keratotomy

– CXL: Corneal Cross-Linking

• For Corneal Debridement:

– AKA: Super-K or Superficial Keratectomy • ABMD / EBMD / MDF: Map-Dot-Fingerprint or

Anterior or Epithelial Basement Membrane Dystrophy

• RCE: Recurrent Corneal Erosion

Methods for Epi Removal

• PRK & CXL :– Excimer Laser

– Amoils Brush

– Alcohol Well (ETOH)• Light shield

• Wexel Sponge

• ABMD / RCE: – Cellulose Sponge

Spears (Weck-Cell®)

– Knife / Blade• Tooke knife: hockey puck

• Beaver blade: disposable

PRK – Excimer Laser

Epithelial Removal

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PRK Candidates

• Corneal Thickness

• At risk Corneal Topography

• History of EBMD

• Occupational or Recreational

– Military, Police, Martial Arts

PRK Epithelial Removal

• Remove enough epithelial tissue

– Allows sufficient stromal exposure for Excimer laser

– Allows compensation for central cornea thickness

• For nomogram development, removal of epithelium. should be consistent in both technique and timing.

• Care must be taken to not remove too little or too much tissue.

Myopia 6 to 8 mm optical zone

Hyperopia 9mm optical zone

Mixed

Astigmatism

9mm optical Zone

PRK Procedure

• Epithelium Removal:– CHEMICAL Removal:

• Uses dilute alcohol 5 to 20%

– MECHANICAL Removal: • Brush or Scrape manually

with a mechanical brush or

surgical spatula

– TRANSEPITHELIAL Removal: • Ablate epi with excimer laser

followed by manual scrape

PRK Procedure

PRK Procedure

• Patient fixates

on target

• Tracker is engaged

• Ablation initiated– Paused as needed

– Minimize time to minimize

corneal dehydration

• MITOMYCIN-C – Used if applicable

PRK Procedure

• Bandage Contact Lenses (BCL’s)

– Bandage lens placed after PRK

– Remove speculum

– BCL used for patient comfort

– Float lens for removal

or use forceps

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Excimer Laser

Collagen Cross-Linking (CXL)

Collagen CXL: Procedure

• Epi-Off CXL:– Conventional methods of

epithelial removal:

• ETOH

• Femto-laser

• Mechanical device

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Collagen Cross-Linking (CXL)

Epithelial Removal

• Removal diameter

– Large enough to allow

maximum saturation

of Riboflavin

– Small enough as to

not prolong healing

• Technique:

– Epithelial-ON vs. Epithelial-OFF

• Studied to measure its effectiveness in the

overall outcome of the procedure 16

Epi Removal: Amoils Brush

• Battery operated rotary epithelial

scrubber with disposable brush head

– Available in 3 sizes:

• 8.0 mm

• 9.0 mm

• 9.5mm

– Quick and

efficient

epithelial removal allowing for

less corneal dehydration

Epi Removal: Amoils Brush

• Moisten the toothbrush bristles with water

(simulated BSS)

• Turn on the battery operated

toothbrush and gently touch

the surface of the cornea .

– Steady the eye with the fixation ring (if used)

– Use enough pressure to ensure

the epithelium will be removed.

– Perform this for at least 30 seconds.

– Once complete, turn off the brush and

remove the fixation ring (if used).

• Use a surgical sponge to remove the epithelium and

to prepare the surface of the cornea.

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Amoils Brush Epi Removal: Alcohol (ETOH)

• Various options for alcohol dilution strength and time of exposure

– Softens epithelium making for easy removal

– Use of a well and sponge

• Can be used to avoid collateral damage to neighboring epithelial tissue by isolating the alcohol exposure

Alcohol Solution with Well Alcohol Solution with

Light Shield (Sponge)

Post-Epi Removal: CXL Procedure

• Riboflavin 0.1% Drops

– Average 30 minutes duration with a drop every

2 minutes until Riboflavin is present throughout

the cornea and in the anterior chamber

– If corneal thickness is

too thin for treatment,

additional hypotonic solution

may be used to temporarily

thicken the cornea

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Collagen CXL: Slit Lamp Exam

✓ Riboflavin must be present in the entire cornea

including the anterior chamber before the next phase

of the treatment can proceed – UV Light Exposure

✓ Looks orange throughout the cornea and A/C

✓ Once full saturation is confirmed by slit lamp

observation, central pachymetry is checked

to ensure greater than 400 microns

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Collagen CXL: UV Light

• UV Light + Riboflavin• Eye is exposed to UV Light which activates the Riboflavin

which improves Collagen Crosslinking

• Exposure of UV-A light is done for 30 minutes at 5mW

• Bandage Contact Lens– For comfort and removed similar to surface ablation (PRK)

with laser vision correction

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Anterior Basement

Membrane Dystrophy

Anterior/ Epithelial Basement

Membrane Dystrophy: ABMD • Most common corneal

dystrophy, affecting

about 2% of the population.

More common in the elderly.

• About 10% experience RCE

as a consequence of faulty

attachment complexes.

• Hemi-desmosomes of the

basal epithelial cells, the

underlying basement

membrane,

• The sub-adjacent anchoring

fibrils of Bowman's layer

attach poorly.

Anterior Basement Membrane

Dystrophy: ABMD / EBMD

• After an erosion, persistence

of devitalized epithelium and

fragments of basement

membrane may inhibit normal

re-epithelialization and

formation of secure

attachment complexes.

• Superficial debridement for

removal of abnormal

epithelium and basement

membrane thereby leaving

a smooth substrate of

Bowman's layer.

ABMD• The adjacent normal epithelium can resurface this area,

allowing formation of competent attachment complexes

and resulting in prompt cessation of erosive symptoms with

much reduced frequency of recurrences.

• Some pts. can have reduced

vision &/or RCE from the

extreme deposition of an

abnormal BM & collagenous

material btwn. the epithelium

and Bowman's layer.

• May lead to irregular

astigmatism & abnormal

tear breakup.

• Patients typically complain of monocular visual

distortion, diplopia, or “ghost images.”

ABMD: Superficial Keratectomy

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ABMD + Dry Eye Syndrome

• 65-year-old Russian female

• History of ABMD & with

secondary Dry Eye

Syndrome

• Oc Meds: Restasis bid OU,

Preservative Free Artificial

Tears qid OU

• Eyes hurt all the time, tired

of pain/dryness especially

when reading

• Wants to try alternative tx

for symptoms

• Start treatment with

Aminotic membrane

• Followed for 3 wks OS,

then 2 wks OD following

Superficial Keratectomy

• Can be performed on other

epithelial defects, post-

debridement

ABMD / EBMD

Typical Map-Dot-Fingerprint Dystrophy:loose epithelium was debrided then placed with A.M. lens to aid in its wound healing.

• Central epithelium is removed with

a dry cellulose sponge. Central

cornea with epithelium removed.

• Cellulose sponge is used to identify

a plane in the fibrous membrane.

Fibrous membrane is then peeled

as continuous cellophane-like

sheets with jeweler's forceps.

• Irregular epithelium, aberrant

basement membrane zone, and

dense sub-epithelial fibrous tissue

that has replaced Bowman's layer.

• Once removed, a smooth substrate

of intact Bowman's layer remains

after re-epithelialization with the

elimination of irregular astigmatism

ABMD: Superficial Keratectomy

.

Recurrent Corneal Erosion

• May occur secondary to corneal injury or

spontaneously. • In the latter case, some predisposing factor, such as

diabetes or a corneal dystrophy, may be the underlying

cause.

• Management of RCE syndrome is

usually aimed at regenerating or

repairing the epithelial basement

membrane to restore the adhesion

between the epithelium and the

anterior stroma.

• Painful RCE syndrome, results from abnormalities in

the epithelial basement membrane.

Recurrent Corneal Erosion

• 31-year-old male4th Grade teacherfrom Jersey– Picked up students’

exams and abradeshis cornea with a large,central paper cut

– Placed on BCL+antibiotics without any relief

• Recurred 5 more times in a 4 month period.

– Needed to debride damaged tissue

– Placed Amniotic Membrane

Epithelial Removal

• Sponge / Blade:

– Start at nasal edge of optical zone

– Use quick vertical strokes across the

visual axis

– Once the most of the

epithelium is removed,

– Swipe area to assure

no cells are left

– Surface should appear smooth

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Corneal Debridement:

Sponge Spear & BladeRecurrent Corneal Erosion

• Day of Debridement

• 3 days post-op

Recurrent Corneal Erosion

• Post Debridement - 7 days post-op

Emerging Therapeutic Options:

Amniotic Membrane

Active amniotic membrane is a biologic

therapy that can:

• Promote regenerative

healing

• Reduce inflammation

• Minimize scar formation

• Minimize pain

• Amniotic membrane is the

inner most lining of the

placenta (amnion) and shares

the same cell origin as the

fetus

• Contains cytokines and growth

factors

• Anti-Inflammatory

(protease inhibitors)

• Anti-Angiogenic

• Anti-Scarring

• Aids in rapid wound healing

and re-epithelialization

Amniotic Membrane

Findings:

• NO High Molecular

Weight Hyaluronic

Acid found in Dry

Membrane

• Cryo-Tek noted an

abundance of HMW

Hyaluronic Acid

• Important for

regenerative

properties.

Desai et al, ARVO, 2012

M Healon® CryoTek™ Dry

High MW HA

Low MW HA

Comparison of Dry vs. Cryopreserved

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Study Results: Absence of PTX3

in Dry Membrane

PTX3 is the activator for

Heavy Chain (HC)-

Hyaluronic Acid (HA)

complex.4

PTX3 is abundantly present

in cryopreserved AM

PTX3 was poorly detected

in dried AM.

This result suggests that

dehydration processing

damages the integrity of

HC-HA complex.

CryoTek™ Dry

Desai et al, ARVO, 2012

HC•HA

TSG-6

II

HC

bikunin

He et al, J Biol Chem, 284:20136-46, 2009Zhang et al, J Biol Chem, 287:12433-44, 2012

Formation of HC-HA Complex in

Amniotic Membrane

Formation of HC•HAFormation of HC•HA

Complex with PTX3

Adult: PTX3 Complex activates complement pathway by phagocytes, DCs, fibroblasts , etc.

PTX3 Complex: strongly inhibits inflammation and angiogenesis and

promotes regeneration.

Hands-On Workshop

Procedures for Epithelial Removal

Methods for Epi Removal

• Station 1:

– Amoils Brush

• Station 2:

– Alcohol Well

– Wexel Sponge

– Light shield

Methods for Epi Removal

• Station 3:

– CXL

• Riboflavin installation

• BCL application

• Station 4:

– Blade:

• Tooke knife: hockey puck

• Beaver blade: disposable

It’s Time to Cut…Loose…

• Break time 15min.

• Start with current Station #

• Each station will be 15min.

• Then go to next station –

you will have 5 min.

between stations

• An hour to complete all

four stations.