lasik, epi–lasik and prk past present and future · 2010-09-20 · epi-lasik i susurface ablation...
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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
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