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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