LASIK, Epi LASIK and PRK Past present and future

LASIK, Epi LASIK and PRK Past present and future Ioannis G. Pallikaris MD, PhD Institute of Vision and Optics University of Crete Medical School Heraklion Crete Greece

Photorefractive Keratectomy Kerr-Muir MG, Trokel SL, Marshall J, Rothery S. Am J Ophthalmol. 1987 Mar 15;103(3 Pt 2):448-53 PRK used since 1980 s Minimally invasive procedure predictable, safe up to -6.00D Postoperative pain Corneal haze Regression of effect Delayed visual rehabilitation.

1990 Lasik Invention Pallikaris IG, Papatzanaki ME, Stathi EZ,Frenschock O, Georgiadis A. Lasers Surg Med. 1990;10(5):463-8.

Lasik Advantages Effective procedure High predictability Fast, Painless Recovery Lack of Sub-Epithelial Haze Pallikaris IG et al..lasers Surg Med 1990 Are mainly due to the creation of a corneal hinged flap

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)

The deep lamellar cut will always carry the risk of future iatrogenic ectasia Long term stability

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, flapinduced aberrations Pallikaris IG et al. JCRS 2002

Sub Bowman 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.

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, Erlagen Germany)

Flap thickness 79.88 ±6.94µm for all eyes (range, 70 to 93µm) number of eyes 18 16 14 12 10 8 6 4 2 0 70-79 80-89 90-100 flap thickness (µm)

Results I Mean sph. equivalent. on the 1 st postoperative day was -0.48 ±0.88 D (range, -2.75 to 0.75 D) Mean sph. equivalent on the 3 rd postoperative day was -0.28±0.49 D (range : -2 to 0.75 D) sph.equivalent (D) 0-1 -2-3 -4-5 -6 1 2-0,481382979-0,281914894 3-5,111702128 preop 1st postop day 3rd postop day

Results II Mean UCVA on the 1 st postoperative day was 0.80 ±0.21 (range, 0.20 to 1.20) 1 0,9 0,8 0,7 Mean UCVA on the 3 rd postoperative day was 0.94 ±0.21 UCVA 0,6 0,5 0,4 0,3 0,2 0,1 (range, 0.30 to 1.20) 0 1 2 3 preop 1st postop day 3rd postop day

Confocal images after ultra thin flap (fast subepithelial nerve plexus recovery) PREoperative POSToperative POSToperative (1month) (3months) Absence of subepithelial nerves Nerve regeneration

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.

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

EVOLUTION OF PHOTOREFRACTIVE TREATMENTS FOR THE CORRECTION OF AMETROPIAS PRK FDA approval:1995 Epithelial injury Postoperative pain Late visual recovery Risk of Haze Risk of corneal ectasia Unpredictable flap induced aberrations Intrastromal incision In a deep plane in the stroma LASIK FDA approval:1999 Advanced Surface Ablations

Reasons for selecting a surface treatment Flap induced aberrations Flap related complications Preoperative dry Eye Thin corneas for attempted correction Epithelial basement membrane dystrophies

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.

Epi-LASIK I Surface ablation (epi( epi-polispolis superficial) Epithelium is separated as a sheet and replaced on the ablated stroma Special device (Epikeratome( Epikeratome) -Automated procedure No use of alcohol Dealing with drawbacks of PRK (postoperative discomfort, late visual recovery, haze) and avoiding risks of LASIK Suitable in thin corneas

Epikeratome Corneal stroma Bowman s layer Intraocular Pressure

Epi-LASIK II Centurion SES Epikeratome for epithelial separations (Norwood Abbey, Australia)

Epi-LASIK III

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

EPI-LASIK: Postoperative course 1 hour post surgery 1 day postop Epithelial flap borders Epithelial flap borders

DAY 3

Reepithelization day

Confocal Images - Ablation 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 1 0-0,3-0,19-0,21-0,17 preop 1m 3m 6m 1y -1 Mean SEq -2-3 -3,58 Average Sph Eq -4-5 -6 Time

Scattergram of Attempted vs. Achieved Sph.Eq. 9 8 7 Attempted(D) 6 5 4 3 1 month (N=142) 3 months (N=111) 6 months (N=79) 2 1 0 0 1 2 3 4 5 6 7 8 9 Achieved(D)

Uncorrected Visual Acuity post Epi-LASIK 120% 100% 80% 95% 99% 97% 97% 81% 91% 93% 86% 70% Reep % eyes 60% 1 month 3 months 6 months 1 year 40% 20% 20% 0% 20/40 or better 20/25 or better UCVA

BCVA Line gain/loss 70% 60% 58% 50% 48% 48% 46% % eyes 40% 30% 42% 40% 37% 1 month (N=142) 3 months (N=111) 6 months (N=79) 1 year (N=26) 20% 20% 17% 10% 0% 12% 10% 10% 4% 5% 2% 0% 0% 0% 0% 1% -2-1 0 1 2 Snellen lines

Incidence of corneal haze after myopic Epi-LASIK 100% 90% 89% 82% 80% 70% 67% % of treated eyes 60% 50% 40% 49% 39% 1 month 3 months 6 months 1 year 30% 27% 20% 10% 0% 16% 11% 12% 5% 1% 0% 0% 1% 1% 0% 0% 0% 0% 0% clear trace mild moderate marked Haze grade

Mean pain score on the first postoperative day (N=163) 4 Oral medication pain score 3 2 1 0 Pain w/o medication Burning feeling Discomfort 1,46 1,07 0,82 0,65 0,38 0 2 4 6 8 10 12 14 16 18 20 22 24 26 postoperative hours The mean pain scores remained below the threshold of burning sensation 0,18 mean pain

PRK Revised No need for suction (RD, Glaucoma concern) No risk of corneal stromal cut No keratome needed

Prophylactic PRK MMC Catia Gambato,, MD, Ophthalmology Volume 112, Number 2, February 2005 Gaston O. Lacayo III Curr Opin Ophthalmol 16:256 259. 259. ª 2005 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 Safety up to 9 yrs max experience

MMC application

MMC Therapeutic application Laura T. Muller, MD, J Cataract Refract Surg 2005; 31:291 296 296 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)

Cellular effects of mitomycin-c 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

Intaoperative corneal cooling in PRK Yoshihiro Kitazawa, MD, J Cataract Refract Surg 1999; 25:1349 1355 1355 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

Postop pain score

Postop haze

Predictability

LASEK Hassan Hashemi,, MD J Refract Surg 2004;20:217-222 222 Jin Kook Kim, MDJ J Cataract Refract Surg 2004; 30:1405 1411 1411 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)

Latest Research

Cytochrome-c peroxidase effect 3 times application after PRK vs placebo Significantly faster reepithelialization in treated eyes Sergio Zaccharia Scalinci,, MD, J CATARACT REFRACT SURG - VOL 31, OCTOBER 2005

Cultured epithelial cells on PRK surface Yasutaka Hayashida, Osaka, Japan Investigative Ophthalmology & Visual Science, February 2006, Vol.. 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

Cultured epithelial cells on PRK surface Yasutaka Hayashida, Osaka, Japan Investigative Ophthalmology & Visual Science, February 2006, Vol.. 47, No. 2 Immature epithelium Activated keratocytes Normal epithelium and stroma

Thank you for your attention! Institute of Vision and Optics University of Crete Medical School Heraklion Crete Greece