View
218
Download
0
Category
Preview:
Citation preview
2/1/2018
1
“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
2/1/2018
2
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
2/1/2018
3
Excimer Laser
Collagen Cross-Linking (CXL)
Collagen CXL: Procedure
• Epi-Off CXL:– Conventional methods of
epithelial removal:
• ETOH
• Femto-laser
• Mechanical device
15
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.
2/1/2018
4
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
23
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
24
2/1/2018
5
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
25
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
2/1/2018
6
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
2/1/2018
7
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
2/1/2018
8
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.
Recommended