LASIK, Epi LASIK and PRK Past present and future

(1)

LASIK,

Epi

_Epi

–

_–

LASIK

_LASIK

and PRK

Past present and future

Institute of Vision and Optics

University of Crete Medical School

Heraklion

Heraklion Crete GreeceCrete Greece

(2)

Photorefractive Keratectomy

PRK used since

1980

’

s

Minimally invasive

procedure predictable,

safe up to

-

6.00D

Postoperative pain

Corneal haze

Regression of effect

Delayed visual

rehabilitation.

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

(3)

1990

Lasik

_Lasik

Invention

_Invention

Pallikaris IG, Papatzanaki ME, Stathi EZ,Frenschock O, Georgiadis A.

(4)

Lasik

Advantages

_Advantages

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

(5)

Ideal flap thickness I

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

easier intraoperative

manipulations

better flap-to-bed fitting fewer striae

fewer intraoperative

complications

(buttonhole, free cuts, steps)

(6)

The deep lamellar cut will always

carry the risk of future iatrogenic

ectasia

(7)

Ideal flap thickness II

Shift towards

thinner

flaps

because of

Post-Lasik corneal ectasia

Pallikaris IG et al.JCRS 2001

Need for higher attempted

corrections

Kymionis GD et al.Am J Ophthalmol 2004

Trend for bigger ablation

zones, supplementary topography, wavefront guided treatments, flap-induced aberrations

(8)

Sub Bowman

Lasik

_Lasik

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 stromal tissue 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.

(9)

Prospective 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,

(10)

Flap 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) n u m b e r o f e y e s

(11)

Results

I

_I

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

sp h .e q u iv a le n t (D )

(12)

Results

II

_II

Mean UCVA on the 1st

postoperative day was

0.80 ±0.21

(range, 0.20 to 1.20)

Mean UCVA on the 3rd

postoperative day was

0.94 ±0.21 (range, 0.30 to 1.20) 0,1₀ 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

U

C

V

(13)

Confocal images after ultra thin flap

(fast

subepithelial

nerve plexus recovery)

PREoperative POSToperative POSToperative (1month) (3months)

(14)

Complications

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.

(15)

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 head

microkeratome provides a safe and accurate procedure without any intraoperative complications

(16)

Advanced Surface Ablations

•Postoperative pain •Late visual recovery

•Risk of Haze

Risk of corneal ectasia Unpredictable

flap induced aberrations

Epithelial injury

Intrastromal incision In a deep plane

in the stroma

EVOLUTION OF PHOTOREFRACTIVE TREATMENTS FOR THE CORRECTION OF AMETROPIAS

PRK

FDA approval:1995

LASIK

FDA approval:1999

(17)

Reasons for selecting a surface

treatment

Flap induced aberrations

Flap related complications

Preoperative dry Eye

Thin corneas for attempted correction

Epithelial basement membrane

(18)

Wavefront 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.

(19)

Epi

-

_-

LASIK I

_{LASIK 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 LASIK

late visual recovery, haze) and avoiding risks of LASIK

(20)

Epikeratome

Corneal stroma

Bowman’s layer

(21)

Epi

-

_-

LASIK II

_{LASIK II}

Centurion SES Epikeratome for epithelial separations (Norwood Abbey, Australia)

(22)

Epi

(23)

Histological 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

(24)

1 day postop

EPI-LASIK: Postoperative course

1 hour post surgery

Epithelial flap borders

(25)

(26)

Reepithelization day

(27)

Confocal

Images

_Images

-

_-

Ablation Zone

_{Ablation Zone}

Pre op 1 Month P op 3 Months Pop

(28)

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

(29)

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 M e a n S E q Average Sph Eq

(30)

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) A tt e m p te d (D ) 1 month (N=142) 3 months (N=111) 6 months (N=79)

(31)

Uncorrected Visual Acuity post Epi-LASIK 81% 20% 95% 70% 99% 91% 97%97% _93% 86% 0% 20% 40% 60% 80% 100% 120% 20/40 or better 20/25 or better UCVA % e y e s Reep 1 month 3 months 6 months 1 year

(32)

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 2 Snellen lines % e y e s 1 month (N=142) 3 months (N=111) 6 months (N=79) 1 year (N=26)

(33)

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 marked

Haze grade % o f tr e a te d e y e s _{1 month} 3 months 6 months 1 year

(34)

Mean pain score on the first

postoperative day (N=163)

1,46 1,07 0,82 0,65 0,38 0,18 0 1 2 3 4 0 2 4 6 8 10 12 14 16 18 20 22 24 26 postoperative hours p a in s c o re mean pain Oral medication

Pain w/o medication

Burning feeling

Discomfort

The mean pain scores remained below the threshold of burning sensation

(35)

PRK Revised

No need for suction (RD, Glaucoma concern)

No risk of corneal

stromal

cut

(36)

Prophylactic PRK MMC

Catia

Catia GambatoGambato, MD, , MD, Ophthalmology Ophthalmology Volume 112, Number 2, February 2005Volume 112, Number 2, February 2005

Gaston O.

Gaston O. LacayoLacayoIII III CurrCurrOpinOpinOphthalmolOphthalmol16:25616:256——259. 259. ªª20052005

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

effective. >75um ablations.

Reduction of

myofibroblast

activity / haze

(compared to Corticosteroids)

Faster visual recovery (CSF) and

confocal

microscopic normalization

(37)

MMC application

(38)

MMC Therapeutic application

Laura T. Muller, MD, J Cataract Refract

Laura T. Muller, MD, J Cataract Refract SurgSurg2005; 31:2912005; 31:291––296296

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

Post complicated

Lasik

flap

(Minimum 3 weeks waiting time.)

PTK for corneal dystrophies

Haze / regression treatment post PRK

Combination with PTK

Reduce attempted correction (15

-

80% based on

PTK need)

(39)

Cellular effects of

mitomycin

-

C on human corneas

after photorefractive keratectomy

Human corneas: 0, 1min, 2min MMC

Delay in epithelial healing @ 2min

Delay in anterior KC repopulation @2 >1 min

No difference in endothelial, mid and posterior

kc

populations.

Conclusion: 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

(40)

Intaoperative

corneal cooling in PRK

_{corneal cooling in PRK}

Yoshihiro 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

BSS)

Prospective randomized treatment >8D myopia.

F/U 2 yrs

Effects in pain, haze, regression

Practically: We apply frozen CL immediately

post PRK for 1 min

(41)

Postop

(42)

Postop

(43)

Predictability

(44)

LASEK

Hassan

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

Jin Kook Kim, MD

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

Less stimulation of

kc

than PRK in rabbits (high

ablations)

Advantage

vs

PRK for small

–

medium

corrections ?

Not as good as LASIK for high corrections

(12.3% haze, regression)

(45)

Latest Research

(46)

Cytochrome

-

_-

c

_c

peroxidase

_peroxidase

effect

_effect

Sergio

Sergio ZacchariaZaccharia ScalinciScalinci, MD,, MD,

J CATARACT REFRACT SURG

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

3 times application after

PRK

vs

placebo

Significantly faster

reepithelialization

in

treated eyes

(47)

Cultured epithelial cells on PRK surface

Yasutaka

Yasutaka HayashidaHayashida, , Osaka, JapanOsaka, Japan

Investigative Ophthalmology & Visual Science, February 2006, Vol

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

Limbal

stem cells harvested

–

cultured

preop

Cultured cells applied on PRK surface

immediately

postop

These epithelial cells SURVIVE

Ideal corneal

stromal

profile with no haze @ 2

months in rabbits

(48)

Cultured epithelial cells on PRK surface

Yasutaka

Yasutaka HayashidaHayashida, , Osaka, JapanOsaka, Japan

Investigative Ophthalmology & Visual Science, February 2006, Vol

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

Immature epithelium Activated keratocytes

(49)

Thank you for your attention!

Institute of Vision and Optics

University of Crete Medical School

Heraklion