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epi LASEK: creating epithelial epi LASEK: creating epithelial flaps using variable alcohol flaps using variable alcohol concentrations and variable concentrations and variable
duration of exposureduration of exposure
epi LASEK: creating epithelial epi LASEK: creating epithelial flaps using variable alcohol flaps using variable alcohol concentrations and variable concentrations and variable
duration of exposureduration of exposurePravin K Vaddavalli, Subramaniam SV, Sangwan VS, Pravin K Vaddavalli, Subramaniam SV, Sangwan VS,
Parulkar G, Vemuganti GKParulkar G, Vemuganti GK
Cornea & Refractive surgery ServiceCornea & Refractive surgery ServicePathology ServicePathology Service
LV Prasad Eye InstituteLV Prasad Eye InstituteIndiaIndia
Pravin K Vaddavalli, Subramaniam SV, Sangwan VS, Pravin K Vaddavalli, Subramaniam SV, Sangwan VS, Parulkar G, Vemuganti GKParulkar G, Vemuganti GK
Cornea & Refractive surgery ServiceCornea & Refractive surgery Service
Pathology ServicePathology ServiceLV Prasad Eye InstituteLV Prasad Eye Institute
IndiaIndia
The authors have no financial interests to disclose
IntroductionIntroductionIntroductionIntroduction
Surgeon
acceptability
Moderate
skills
Reproducible Stable Accurate Safe Reversible
RK + ++ + - ? ? -
LASIK/PRK +++ ++ +++ ++ ++ ? -
Phakic IOL + + - ? + ? ?
Clear lens
extraction
- +++ +++ ? + ? -
INTACS - - ? + + ? +
• Refractive surgery still has many drawbacks, chief among which is
non reversibility
• Corneal implants like inlays and onlays can achieve this
IntroductionIntroductionIntroductionIntroduction
1 week
1 month
6 months
12 months
24 months
Progressive loss of clarity with corneal inlays
Corneal implantsBarraquer 1960
Dohlman 1967
Choyce 1970
Beekhuis 1986
IntroductionIntroductionIntroductionIntroduction
Synthetic Onlay
Epithelium
Stroma
Lens
Ideal position for a corneal
implant is just beneath the basement
membrane of the corneal
epithelium
To achieve this we need to
create a viable epithelial flap beneath which
to place the onlay
Materials and methodsMaterials and methodsMaterials and methodsMaterials and methods
• 3 groups3 groups
• Group A: LASEK – alcohol assistedGroup A: LASEK – alcohol assisted
• Group B: epi LASIK – epimicrokeratomeGroup B: epi LASIK – epimicrokeratome
• Group C: epi LASEK – combination of Group C: epi LASEK – combination of
alcohol exposure and epimicrokeratomealcohol exposure and epimicrokeratome
• 3 groups3 groups
• Group A: LASEK – alcohol assistedGroup A: LASEK – alcohol assisted
• Group B: epi LASIK – epimicrokeratomeGroup B: epi LASIK – epimicrokeratome
• Group C: epi LASEK – combination of Group C: epi LASEK – combination of
alcohol exposure and epimicrokeratomealcohol exposure and epimicrokeratome
PurposePurposePurposePurpose
To create a viable epithelial flap/pocket using a To create a viable epithelial flap/pocket using a
combination of alcohol and an combination of alcohol and an
epimicrokeratomeepimicrokeratome
To create a viable epithelial flap/pocket using a To create a viable epithelial flap/pocket using a
combination of alcohol and an combination of alcohol and an
epimicrokeratomeepimicrokeratome
Materials and methodsMaterials and methodsMaterials and methodsMaterials and methods
Group A: LASEKGroup A: LASEK
• 5 patients undergoing PRK5 patients undergoing PRK
• 20% isopropyl alcohol20% isopropyl alcohol
• 20 sec exposure time20 sec exposure time
• Epithelial flap sent for Epithelial flap sent for
histologyhistology
Group A: LASEKGroup A: LASEK
• 5 patients undergoing PRK5 patients undergoing PRK
• 20% isopropyl alcohol20% isopropyl alcohol
• 20 sec exposure time20 sec exposure time
• Epithelial flap sent for Epithelial flap sent for
histologyhistology
Alcohol Debridement of the Corneal Epithelium in PRK and LASEK: An Electron Microscopic Study AC Browning, S
Shah, HS Dua, SV Maharajan, T Gray, MA Bragheeth. Invest Ophthalmol Vis Sci. 2003;44:510–513
Group B: epi LASIKGroup B: epi LASIK
• 5 patients undergoing epi 5 patients undergoing epi
LASIKLASIK
• Moria epi K, Zyoptix XP epi or Moria epi K, Zyoptix XP epi or
Norwood epimicrokeratomeNorwood epimicrokeratome
• Epithelial flap sent for Epithelial flap sent for
histologyhistology
Group B: epi LASIKGroup B: epi LASIK
• 5 patients undergoing epi 5 patients undergoing epi
LASIKLASIK
• Moria epi K, Zyoptix XP epi or Moria epi K, Zyoptix XP epi or
Norwood epimicrokeratomeNorwood epimicrokeratome
• Epithelial flap sent for Epithelial flap sent for
histologyhistology
Material and methods: epi LASEK: Material and methods: epi LASEK: Group CGroup CMaterial and methods: epi LASEK: Material and methods: epi LASEK: Group CGroup C
• 5 eyes undergoing PRK5 eyes undergoing PRK
• Pre treated with 20% or 10% isopropyl alcoholPre treated with 20% or 10% isopropyl alcohol
• Treatment time 10 sec vs 5 secTreatment time 10 sec vs 5 sec
• Flap creation with Moria. Zyoptix XP or Norwood Flap creation with Moria. Zyoptix XP or Norwood
epimicrokeratomeepimicrokeratome
• Epithelial flap sent for histologyEpithelial flap sent for histology
• 5 eyes undergoing PRK5 eyes undergoing PRK
• Pre treated with 20% or 10% isopropyl alcoholPre treated with 20% or 10% isopropyl alcohol
• Treatment time 10 sec vs 5 secTreatment time 10 sec vs 5 sec
• Flap creation with Moria. Zyoptix XP or Norwood Flap creation with Moria. Zyoptix XP or Norwood
epimicrokeratomeepimicrokeratome
• Epithelial flap sent for histologyEpithelial flap sent for histology
Periodic Acid Schiff 100 X showing irregular basement membrane and disrupted basal
epithelial cells
Results: Group A: LASEKResults: Group A: LASEKResults: Group A: LASEKResults: Group A: LASEK
Literature also shows compromised epithelial
cell viability *
* Tanioka H, Hieda O, Kawasaki S, Nakai Y, Kinoshita S. Assessment of epithelial integrity and cell viability
in epithelial flaps prepared with the epi-LASIK procedure. J Cataract Refract Surg. 2007 Jul;33(7):1195-200.
Intact Basal epithelial cell layer
Disrupted Basal epithelial cell layer
Moria epi microkeratome – Periodic Acid Schiff 100 X
Results: epi LASIK: group BResults: epi LASIK: group BResults: epi LASIK: group BResults: epi LASIK: group B
Basal epithelial cell layer – loose desquamating cells with vacuoles
Norwood microkeratome – Periodic Acid Schiff 100 X
Moria epimicrokeratome with 20% isopropyl alcohol for 5 sec, PAS stain
Mostly regular cut
Moria epimicrokeratome with 20% isopropyl alcohol for 5 sec, PAS stain
Basal cells not disrupted in most
sections
Scalloping of basal epithelial cell layer, ? artifactual
Moria epimicrokeratome with 20% isopropyl alcohol for 5 sec, PAS stainNorwood epimicrokeratome with 10% isopropyl alcohol for 10 sec, PAS
Regular basal cell layer with basement
membrane
Norwood epimicrokeratome with 10% isopropyl alcohol for 10 sec, HE
Basement membrane
intact
Moria epimicrokeratome with 10% isopropyl alcohol for 5 sec, PAS
Intact basement membrane
Results: Group C: epi LASEKResults: Group C: epi LASEKResults: Group C: epi LASEKResults: Group C: epi LASEK
Transmission Electron Microscopy 1000 X showing intact regular basement membrane
ResultsResultsResultsResults
• LASEK resulted in disruption of epithelial basal cellsLASEK resulted in disruption of epithelial basal cells
• Epi LASIK resulted in cleavage through basal cellsEpi LASIK resulted in cleavage through basal cells
• Epi LASEK resulted in most native morphology of Epi LASEK resulted in most native morphology of
basal cellsbasal cells
• 10% isopropyl alcohol for 5 sec pre treatment 10% isopropyl alcohol for 5 sec pre treatment
results in most regular epithelial flap results in most regular epithelial flap
• LASEK resulted in disruption of epithelial basal cellsLASEK resulted in disruption of epithelial basal cells
• Epi LASIK resulted in cleavage through basal cellsEpi LASIK resulted in cleavage through basal cells
• Epi LASEK resulted in most native morphology of Epi LASEK resulted in most native morphology of
basal cellsbasal cells
• 10% isopropyl alcohol for 5 sec pre treatment 10% isopropyl alcohol for 5 sec pre treatment
results in most regular epithelial flap results in most regular epithelial flap
ConclusionsConclusionsConclusionsConclusions
• epi LASEK may be the best way to retain epithelial epi LASEK may be the best way to retain epithelial
viabilityviability
• First step to create viable epithelial flap for the First step to create viable epithelial flap for the
placement of a corneal onlayplacement of a corneal onlay
• Has applications in advanced surface ablationHas applications in advanced surface ablation
• Can result in reduced post op pain, reduced hazeCan result in reduced post op pain, reduced haze
• Need to establish viability of epithelial cells by cell cultureNeed to establish viability of epithelial cells by cell culture
• epi LASEK may be the best way to retain epithelial epi LASEK may be the best way to retain epithelial
viabilityviability
• First step to create viable epithelial flap for the First step to create viable epithelial flap for the
placement of a corneal onlayplacement of a corneal onlay
• Has applications in advanced surface ablationHas applications in advanced surface ablation
• Can result in reduced post op pain, reduced hazeCan result in reduced post op pain, reduced haze
• Need to establish viability of epithelial cells by cell cultureNeed to establish viability of epithelial cells by cell culture
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