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