LASIK, LASIK, EpiEpi––LASIKLASIKand PRK and PRK

Past present and futurePast present and future

Institute of Vision and OpticsInstitute of Vision and OpticsUniversity of Crete Medical SchoolUniversity of Crete Medical SchoolHeraklionHeraklion Crete GreeceCrete Greece

Ioannis G. Pallikaris MD, PhD

Photorefractive Keratectomy Photorefractive Keratectomy

�� PRK used sincePRK used since 19801980’’s s

�� Minimally invasive Minimally invasive procedure predictable, procedure predictable, safe up to safe up to --6.00D6.00D

�� Postoperative painPostoperative pain

�� Corneal hazeCorneal haze

�� Regression of effectRegression of effect

�� Delayed visual Delayed visual rehabilitation.rehabilitation.

Kerr-Muir MG, Trokel SL, Marshall J, Rothery S. Am J Ophthalmol. 1987 Mar 15;103(3 Pt 2):448-53

1990 1990 LasikLasik InventionInventionPallikaris IG, Papatzanaki ME, Stathi EZ,Frenschock O, Georgiadis A.

Lasers Surg Med. 1990;10(5):463-8.

LasikLasik AdvantagesAdvantages

� Effective procedure

� High predictability

� Fast, Painless Recovery

� Lack of Sub-Epithelial Haze

Are mainly due to the creation of a corneal hinged flap

Pallikaris IG et al..Lasers Surg Med 1990

Ideal flap thickness IIdeal flap thickness I

Until recently ideal flap has been 130µm or greater in order to guarantee

� easier intraoperativemanipulations

� better flap-to-bed fitting

� fewer striae

� fewer intraoperativecomplications

(buttonhole, free cuts, steps)

The deep lamellar cut will always The deep lamellar cut will always

carry the risk of future iatrogenic carry the risk of future iatrogenic

ectasiaectasia

Long term stability

Ideal flap thickness IIIdeal flap thickness IIShift towards thinner

flaps because of

� Post-Lasik corneal ectasiaPallikaris IG et al.JCRS 2001

� Need for higher attempted correctionsKymionis GD et al.Am J Ophthalmol 2004

� Trend for bigger ablation zones, supplementary topography, wavefrontguided treatments, flap-induced aberrationsPallikaris IG et al. JCRS 2002

Sub Bowman Sub Bowman LasikLasik

Sub-Bowman LASIK� Might be able to preserve the overall biomechanical

integrity of the cornea� Has better functional results than conventional flaps

(because a thinner flap can be better adjusted to the ablated residual corneal bed as a result of less stromaltissue in it’s composition)

� can induce fewer aberrations than a conventional thicker flap.

It can actually combine the advantages of lamellar (LASIK) and surface (Epi-LASIK) approaches.

Prospective study IProspective study I

� 26 patients (47 eyes) mean age 28.78 ±6.98 (range, 20 to 54 years) underwent Sub Bowman Lasik with the Schwind microkeratome 90-µm single use head

� All patiens underwent Sub Bowman Lasik Using the Allegretto Wave Excimer Laser (WaveLight Technologies, Erlagen Germany)

Flap thicknessFlap thickness� 79.88 ±6.94µm for all eyes (range, 70 to 93µm)

0

2

4

6

8

10

12

14

16

18

70-79 80-89 90-100

flap thickness (µm)

nu

mb

er o

f ey

es

ResultsResults II� Mean sph. equivalent. on the 1st postoperative day was -0.48 ±0.88 D

(range, -2.75 to 0.75 D)

� Mean sph. equivalent on the 3rd postoperative day was -0.28±0.49 D(range : -2 to 0.75 D)

-5,111702128

-0,481382979 -0,281914894

-6

-5

-4

-3

-2

-1

0

1 2 3

preop 1st postop day 3rd postop day

sph.e

quiv

ale

nt (D

)

ResultsResults IIII

� Mean UCVA on the 1st

postoperative day was0.80 ±0.21(range, 0.20 to 1.20)

� Mean UCVA on the 3rd

postoperative day was0.94 ±0.21(range, 0.30 to 1.20)

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1

1 2 3 preop 1st postop day 3rd postop day

UC

VA

Confocal images after ultra thin flapConfocal images after ultra thin flap

(fast (fast subepithelialsubepithelial nerve plexus recovery)nerve plexus recovery)

PREoperative POSToperative POSToperative(1month) (3months)

Absence of subepithelial nerves Nerve regeneration

ComplicationsComplications

� No intraoperative complications occurred

� Few interface particles were observed on slit lamp examination

� On the 1st postoperative day 2 eyes presented microstriae, 4 eyes presented DLK stage 1 and all were successfully treated.

Discussion Discussion

� Sub Bowman Lasik results in the creation of an ultra thin flap which allows the correction of many diopters of myopia without the fear of post-Lasik ectasia

� It can lead to rapid and painless visual rehabilitation that is apparent from the first postoperative day (in dissociation with surface ablations)

� The use of the Schwind 90µm single use headmicrokeratome provides a safe and accurate procedure without any intraoperative complications

Advanced Surface Ablations

•Postoperative pain•Late visual recovery

•Risk of Haze

Risk of corneal ectasiaUnpredictable

flap induced aberrations

Epithelial injury

Intrastromal incisionIn a deep plane

in the stroma

EVOLUTION OF PHOTOREFRACTIVE TREATMENTS FOR THE CORRECTION OF AMETROPIAS

PRKFDA approval:1995

LASIKFDA approval:1999

Reasons for selecting a surface Reasons for selecting a surface treatmenttreatment

� Flap induced aberrations

� Flap related complications

� Preoperative dry Eye

� Thin corneas for attempted correction

� Epithelial basement membrane dystrophies

Wavefront Aberration MapWavefront Aberration Map

Pre Flap Post Flap

Pallikaris et al.Induced optical aberrations following formation of a laser in situ keratomileusis flap.

JCRS 2002; 28(10): 1737-41.

EpiEpi--LASIK ILASIK I

�� Surface ablation (Surface ablation (epiepi--polispolis�� superficial)superficial)

�� Epithelium is separated as a sheet and replaced on the Epithelium is separated as a sheet and replaced on the ablated ablated stromastroma

�� Special device (Special device (EpikeratomeEpikeratome) ) --Automated procedureAutomated procedure

�� No use of alcoholNo use of alcohol

�� Dealing with drawbacks of PRK (postoperative discomfort, Dealing with drawbacks of PRK (postoperative discomfort, late visual recovery, haze) and avoiding risks of LASIKlate visual recovery, haze) and avoiding risks of LASIK

�� Suitable in Suitable in thin corneasthin corneas

EpikeratomeEpikeratome

Corneal stroma

Bowman’s layer

Intraocular Pressure

EpiEpi--LASIK IILASIK II

Centurion SES Epikeratome for epithelial separations

(Norwood Abbey, Australia)

EpiEpi--LASIK IIILASIK III

Histological Studies IHistological Studies I

Epithelium is separated underneath the basement membrane

Pallikaris IG, et al. Epi-LASIK: Comparative histological evaluation of mechanical and alcohol - assisted epithelial separation. JCRS 2003

1 day postop

EPI-LASIK: Postoperative course 1 hour post surgery

Epithelial flap borders

Epithelial flap borders

DAY 3

Reepithelizationday

ConfocalConfocal Images Images -- Ablation ZoneAblation Zone

Pre op 1 Month P op 3 Months Pop

6 Months P op 1 Year P op

Refractive results

�163 treated eyes (average follow-up:12 months)�Attempted correction up to –8 D�Separated epithelial sheets of 9.5 to 10 mm

�All eyes treated with the Wavelight Allegretto

Spherical Equivalent

-3,58

-0,3 -0,19 -0,21 -0,17

-6

-5

-4

-3

-2

-1

0

1

preop 1m 3m 6m 1y

Time

Mea

n S

Eq

Average Sph Eq

Scattergram of Attempted vs. Achieved Sph.Eq.

0

1

2

3

4

5

6

7

8

9

0 1 2 3 4 5 6 7 8 9

Achieved(D)

Att

empt

ed(D

)

1 month (N=142)

3 months (N=111)

6 months (N=79)

Uncorrected Visual Acuity post Epi-LASIK

81%

20%

95%

70%

99%91%

97% 93%97%86%

0%

20%

40%

60%

80%

100%

120%

20/40 or better 20/25 or better

UCVA

% e

yes

Reep

1 month

3 months

6 months

1 year

BCVA Line gain/loss

4%

20%

58%

17%

1%0%

5%

48%

37%

10%

0%2%

40%

48%

10%

0% 0%

42%

46%

12%

0%

10%

20%

30%

40%

50%

60%

70%

-2 -1 0 1 2Snellen lines

% e

yes

1 month (N=142)

3 months (N=111)

6 months (N=79)

1 year (N=26)

Incidence of corneal haze after myopic Epi-LASIK

49%

39%

12%

0% 0%

67%

27%

5%1% 0%

82%

16%

1% 1% 0%

89%

11%

0% 0% 0%0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

clear trace mild moderate markedHaze grade

% o

f tr

eate

d e

yes 1 month

3 months

6 months

1 year

Mean pain score on the first postoperative day (N=163)

1,46

1,07

0,820,65

0,380,18

0

1

2

3

4

0 2 4 6 8 10 12 14 16 18 20 22 24 26

postoperative hours

pai

n s

core

mean pain

Oral medication

Pain w/o medication

Burning feeling

Discomfort

The mean pain scores remained below the threshold of burning sensation

PRK RevisedPRK Revised

�� No need for suction (RD, Glaucoma concern)No need for suction (RD, Glaucoma concern)

�� No risk of corneal No risk of corneal stromalstromal cutcut

�� No No keratomekeratome neededneeded

Prophylactic PRK MMCProphylactic PRK MMCCatiaCatia GambatoGambato, MD, , MD, Ophthalmology Ophthalmology Volume 112, Number 2, February 2005Volume 112, Number 2, February 2005

Gaston O. Gaston O. LacayoLacayo III III CurrCurr OpinOpin OphthalmolOphthalmol 16:25616:256——259. 259. ªª 20052005

�� 0.02% for 2 min standard. 12sec may be as 0.02% for 2 min standard. 12sec may be as

effective. >75um ablations.effective. >75um ablations.

�� Reduction of Reduction of myofibroblastmyofibroblast activity / haze activity / haze

(compared to Corticosteroids)(compared to Corticosteroids)

�� Faster visual recovery (CSF) and Faster visual recovery (CSF) and confocalconfocal

microscopic normalizationmicroscopic normalization

�� Safety up to 9 yrs max experience Safety up to 9 yrs max experience

MMC applicationMMC application

MMC Therapeutic applicationMMC Therapeutic applicationLaura T. Muller, MD, J Cataract Refract Laura T. Muller, MD, J Cataract Refract SurgSurg 2005; 31:2912005; 31:291––296296

Alexandre S. Marcon, M.D.Cornea 21(8): 828–830, 2002.

�� Post complicated Post complicated LasikLasik flapflap

(Minimum 3 weeks waiting time.)(Minimum 3 weeks waiting time.)

�� PTK for corneal dystrophiesPTK for corneal dystrophies

�� Haze / regression treatment post PRKHaze / regression treatment post PRK

�� Combination with PTK Combination with PTK

�� Reduce attempted correction (15Reduce attempted correction (15--80% based on 80% based on

PTK need)PTK need)

Cellular effects of Cellular effects of mitomycinmitomycin--C on human corneas C on human corneas

after photorefractive keratectomyafter photorefractive keratectomy

�� Human corneas: 0, 1min, 2min MMCHuman corneas: 0, 1min, 2min MMC

�� Delay in epithelial healing @ 2minDelay in epithelial healing @ 2min

�� Delay in anterior KC repopulation @2 >1 minDelay in anterior KC repopulation @2 >1 min

�� No difference in endothelial, mid and posterior No difference in endothelial, mid and posterior kckc populations.populations.

�� Conclusion: optimal MMC application 1 minConclusion: optimal MMC application 1 min

J CATARACT REFRACT SURG - VOL 32, OCTOBER 2006

Madhavan S. Rajan, MRCOphth, FRCS, David P.S. O’Brart, MD, FRCS, FRCOphth,Anne Patmore, John Marshall, PhD

IntaoperativeIntaoperative corneal cooling in PRKcorneal cooling in PRKYoshihiro Kitazawa, MD, Yoshihiro Kitazawa, MD, J Cataract Refract J Cataract Refract SurgSurg 1999; 25:13491999; 25:1349––13551355

�� Pre, intra post operative corneal cooling (8deg Pre, intra post operative corneal cooling (8deg

BSS)BSS)

�� Prospective randomized treatment >8D myopia. Prospective randomized treatment >8D myopia.

F/U 2 yrsF/U 2 yrs

�� Effects in pain, haze, regression Effects in pain, haze, regression

�� Practically: We apply frozen CL immediately Practically: We apply frozen CL immediately

post PRK for 1 minpost PRK for 1 min

PostopPostop pain scorepain score

PostopPostop hazehaze

PredictabilityPredictability

LASEKLASEKHassanHassan HashemiHashemi, MD , MD J Refract J Refract SurgSurg 2004;20:2172004;20:217--222222

Jin Kook Kim, MDJin Kook Kim, MDJ Cataract Refract J Cataract Refract SurgSurg 2004; 30:14052004; 30:1405––14111411

�� Less stimulation of Less stimulation of kckc than PRK in rabbits (high than PRK in rabbits (high

ablations) ablations)

�� Advantage Advantage vsvs PRK for small PRK for small –– medium medium

corrections ?corrections ?

�� Not as good as LASIK for high corrections Not as good as LASIK for high corrections

(12.3% haze, regression)(12.3% haze, regression)

Latest ResearchLatest Research

CytochromeCytochrome--cc peroxidaseperoxidase effecteffectSergio Sergio ZacchariaZaccharia ScalinciScalinci, MD,, MD,

J CATARACT REFRACT SURG J CATARACT REFRACT SURG -- VOL 31, OCTOBER 2005VOL 31, OCTOBER 2005

�� 3 times application after 3 times application after

PRK PRK vsvs placeboplacebo

�� Significantly faster Significantly faster

reepithelializationreepithelialization in in

treated eyestreated eyes

Cultured epithelial cells on PRK surfaceCultured epithelial cells on PRK surfaceYasutaka Yasutaka HayashidaHayashida, , Osaka, JapanOsaka, Japan

Investigative Ophthalmology & Visual Science, February 2006, VolInvestigative Ophthalmology & Visual Science, February 2006, Vol. 47, No. 2. 47, No. 2

�� LimbalLimbal stem cells harvested stem cells harvested –– cultured cultured preoppreop

�� Cultured cells applied on PRK surface Cultured cells applied on PRK surface

immediately immediately postoppostop

�� These epithelial cells SURVIVE These epithelial cells SURVIVE

�� Ideal corneal Ideal corneal stromalstromal profile with no haze @ 2 profile with no haze @ 2

months in rabbitsmonths in rabbits

Cultured epithelial cells on PRK surfaceCultured epithelial cells on PRK surfaceYasutaka Yasutaka HayashidaHayashida, , Osaka, JapanOsaka, Japan

Investigative Ophthalmology & Visual Science, February 2006, VolInvestigative Ophthalmology & Visual Science, February 2006, Vol. 47, No. 2. 47, No. 2

Immature epithelium

Activated keratocytes

Normal epithelium and stroma

Thank you for your attention!Thank you for your attention!

Institute of Vision and OpticsInstitute of Vision and OpticsUniversity of Crete Medical SchoolUniversity of Crete Medical SchoolHeraklionHeraklion Crete GreeceCrete Greece