Photorefractive Keratectomy Might be TopographyGuided Photorefractive Better for

Photorefractive Keratectomy Might be Topography-Guided Photorefractive Better for Extreme Myopia Than LASIK Keratectomy for Keratoconus With ASCRS 2016 Simultaneous Collagen Crosslinking Using the New Orleans, Louisiana IVIS Laser David T. C. Lin MD, FRCS(C) 1 Simon P. Holland MB. FRCSC, FRCS, FRCOph, MRCP Simon P. Holland MB. FRCS(C), FRCS(Eng) 1 David T. C. Lin MD FRCSC Pacific Laser Eye Centre 2 Gregory Moloney MBBS, FRANZCO, FRCSC Department of Ophthalmology, The University of British Columbia 1 Umi K. Noh MB BCh BAO, Ms(Ophth) 1. Pacific Laser Eye Centre, Canada Financial Disclosure : 3 Karolien M. M. Termote MD, FEBOpht 2. U. of Sydney, Australia Dr. Lin and Dr. Holland have no financial interests or relationships to disclose. 3. U. Hospital Brussels, Belgium

Financial Disclosure Simon P. Holland MB. FRCSC, FRCS, MRCP - Alcon, Allergan, Clarion David T. C. Lin MD FRCSC - Schwind, PRN Karolien M. M. Termote MD, FEBOpht Umi K. Noh MB BCh BAO, Ms(Ophth) Gregory Moloney MBBS, FRANZCO, FRCSC - No Financial Interest

Laser Ablation: Which Level? § Surface: PRK (epi LASIK, LASEK) § Under a flap: LASIK (FS vs metal) § Intra-stromal: Lenticule removal (Visumax – Re. Lex and SMILE)

Trends for High Myopia § Myopia > -10. 00 D: trend to Phakic IOL, refractive lens exchange if older § Concerns: retinal detachment risk Source: ASCRS Survey of North American refractive surgeons 2014, Duffy

PRK vs LASIK for Myopia § LASIK gives a faster visual recovery than PRK § Effectiveness of two procedures is comparable § LASIK may be less likely than PRK to result in loss of BSCVA

LASIK vs. PRK vs. PIOL § PRK outcomes may be improving with recent advances e. g. Trans-epithelial ablation, § Less haze with standard use of mitomycin C § Less pain with NSAIDs, optimized laser setting § Long term results may be better than LASIK § Risks of ectasia with LASIK § Endothelial cell loss, cataract risk § with Phakic IOL

Methods § Retrospective, consecutive case series and chart review of 261 eyes with myopia >-10. 00 D preoperatively § Allegretto Wavelight laser 400 § 203 eyes trans epithelial PRK, 58 eyes LASIK § One year postoperative § UCVA § CDVA § Manifest refraction § Complications

Result: Pre-operative Data Pre Operative Values LASIK PRK p-value Spherical Equivalent -11. 26 -11. 53 0. 39 Sphere -10. 72 -10. 97 0. 26 Cylinder -1. 08 -1. 11 0. 98 BCVA (Log. Mar) 0. 038 0. 70 Mean values. Data were not normally distributed with the Kolmogorov-Smirnov test, therefore the non-parametric Mann. Whitney U test was used for P values.

Result: Pos-operative Data Pos Operative Values LASIK PRK p-value Spherical Equivalent -0. 30 -0. 26 0. 29 Sphere -0. 06 -0. 05 0. 43 Cylinder -0. 48 -0. 40 0. 24 UCVA (Log. Mar) 0. 15 0. 11 0. 02 CDVA (Log. Mar) 0. 04 0. 03 0. 84 Mean values. Data were not normally distributed with the Kolmogorov-Smirnov test, therefore the nonparametric Mann-Whitney U test was used for P values.

Results: UCVA at 1 Year Pos-Op

Results: Predictability Spherical Equivalent ± 0. 50 D at 1 Year Pos-Op

Results: Gain/Loss CDVA at 1 Year BSCVA Gain/Loss Gain 2 lines or more Gain 1 line No Change Loss 1 line Loss 2 lines or more N PRK 3% 23% 59% 14% 1% 203 LASIK 0% 22% 64% 14% 0% 58

Results: Complications § Temporary loss of vision due to punctate keratopathy (p<0. 05) § 3. 9% (8/203) PRK eyes § 22. 4% (13/58) LASIK eyes § Early haze formation with loss CDVA 2 lines § 3. 0% (6/203) PRK eyes § 0. 0% (0/58) LASIK eyes § Retreatment § 3. 9% (8/203) PRK eyes § 3. 4% (2/58) LASIK eyes

Conclusion §Efficacy and safety may be better with PRK than LASIK for the correction of extreme myopia §UCVA significantly better after PRK than LASIK p=. 02 in extreme myopia §Further improvements expected with improved beam profile of Amaris Schwind 1050 Smartf. ACE

PURPOSE: To compare myopic photorefractive keratectomy (PRK) and laser assisted in-situ keratomileusis (LASIK) using two different laser platforms at the 12 month postoperatively METHODS: The outcomes of 446 myopic transepithelial PRK (TEPRK) eyes performed with Schwind Amaris (SA) were compared to 1798 myopic LASIK eyes performed with Wavelight Allegretto (WA) at 12 month follow-up CONCLUSIONS: UDVA after myopic PRK with Schwind Amaris laser was significantly better than LASIK with Wavelight Allegretto for both moderate and high myopia at one year post-operatively with similar CDVA and safety. Surface ablation with trans epithelial PRK may be a better option than LASIK for moderate and extreme myopia avoiding issues such as post-LASIK ectasia. Submitted to ESCRS 2016

Conclusion: Myopia - LASIK or PRK? Recent and expected improvements in PRK techniques such as trans-epithelial PRK, refractive laser beam profiles, and perioperative management suggest that PRK may be better than LASIK for moderate and extreme myopia