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

2. 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
FD updated 2

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

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

5. 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

6. 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

7. Methods
Retrospective, consecutive case series and chart review of 261 eyes with myopia >-10.00D preoperatively
Allegretto Wavelight laser 400
203 eyes trans epithelial PRK, 58 eyes LASIK
One year postoperative
UCVA
CDVA
Manifest refraction
Complications
Updated 7

8. 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 (LogMar)
0.038
0.70
Updated
----- Meeting Notes (20/04/15 21:48) -----
Both groups were perfectly comparable preoperatively. There was no difference ...
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. 8

9. 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 (LogMar)
0.15
0.11
0.02
CDVA (LogMar)
0.04
0.03
0.84
Updated
----- Meeting Notes (20/04/15 21:48) -----
Postoperatively, we saw that predictability was the same: there was no difference in sphere, SE and Cyl. Also BCVA was similar between both groups. Efficacy was however better in the PRK group: UCVA was significantly better in the PRK gorup.
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. 9

10. Results: UCVA at 1 Year Pos-Op
Updated
----- Meeting Notes (20/04/15 21:48) -----
This figure illustrates the cumulative proportion of eyes achieving a targeted Snellen UCVA. As you can see more patients in the PRK group achieved 20/20 and 20/25. 10

11. Results: Predictability Spherical Equivalent ±0.50D at 1 Year Pos-Op
Updated 11

12. Results: Gain/Loss CDVA at 1 Year
BSCVA Gain/Loss
PRK
LASIK
Gain 2 lines or more 3% 0%
Gain 1 line
23%
22%
No Change
59%
64%
Loss 1 line
14%
Loss 2 lines or more 1% N
203 58
Updated
----- Meeting Notes (20/04/15 21:48) -----
In terms of gain or loss of BSCVA, there was no difference between both groups. Around 60% in both groups had no change in BSCVA, 20% gained one line, and around 15% lost one line. 12

13. 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
3.4% (2/58) LASIK eyes
----- Meeting Notes (20/04/15 21:48) -----
There were few complications: only the temporary loss of vision … was stat. signif.
Early haze form occurred in …
Retreatment rates were as low as 4%. 13

14. 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 SmartfACE 14

15. 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

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