1. Majid Moshirfar, MD, FACS
The John A. Moran Eye Center
Prospective Comparison of Visual Outcomes After Wavefront-guided PRK Versus Wavefront-guided LASIK
Majid Moshirfar, MD, FACS
Mark Mifflin, MD
Joshua A Schliesser, BS
Joann C Chang, MD
Christopher J Kurz, MD

2. Financial Disclosure
This project was supported in part by an unrestricted educational grant from Allergan Inc., Irvine, CA., to the Department of Ophthalmology and Visual Sciences at the University of Utah, John A. Moran Eye Center, Salt Lake City, UT.

3. Purpose
To compare visual outcomes between wavefront-guided PRK and wavefront-guided LASIK at the John A. Moran Eye Center, University of Utah, Salt Lake City, Utah

4. Patients and Methods
This was a prospective study with 203 myopic eyes, with or without astigmatism, that was randomly treated with primary wavefront guided (WFG)-PRK or primary wavefront guided (WFG)-LASIK using the VISX S4 IR CustomVue™ platform.
101 eyes received WFG-PRK
61 eyes were available for analysis at 6 months
102 eyes received WFG-LASIK
57 eyes were available for analysis at 6 months

5. Patients and Methods Primary Outcomes: Secondary outcome measures:
uncorrected visual acuity (UCVA)
best spectacle-corrected visual acuity (BSCVA)
manifest refraction
Secondary outcome measures:
analysis of higher-order aberrations (HOA)
contrast sensitivity (CS)

6. Results: Efficacy
Logarithm of the minimum angle of resolution (log MAR) UCVA at 6 months
-0.03 (approx. 20/19) in the PRK group
-0.07 (approx. 20/24) in the LASIK group (P = 0.544)
Percentage of eyes achieving UCVA 20/20 or better
75% in both groups (p=0.923)
Percentage of eyes achieving UCVA 20/15 or better
30% in the PRK group
19% in the LASIK group (p=0.238)

7. Results: Safety 13% (8/61) WFG-PRK eyes lost one line of BSCVA
Attributed to 5 cases superficial punctate keratitis (SPK) and 3 cases of corneal haze
19% (11/57) WFG-LASIK eyes lost one line of BSCVA
Attributed to 7 cases of SPK, 4 cases of flap microstriae
2% (1/61) WFG-PRK eye lost 2 lines of BSCVA
Attributed to persistent central island
No eyes in both groups had BSCVA worse than 20/25

8. Results: Contrast Sensitivity at 6 months
The difference between preoperative and postoperative CS was not statistically significant at any cycle
Furthermore, the change in CS from baseline between the two groups was not statistically significant at 3, 6, 12, and 18 cycles (p = 0.547, p = 0.435, p = 0.642, p = 0.788, respectively)
Figure 1: The mean contrast sensitivity log values for patients at pre-op and 6 months post PRK.
Figure 2: The mean contrast sensitivity log values for patients at pre-op and 6 months post LASIK.

9. Results: Wavefront analysis and HOAs
Total HOAs in both groups significantly increased at 6 months
Induction was significantly lower in the WFG-PRK group (p= 0.005)
Figure 3: Absolute pre-to postoperative changes in HOA between the groups at six months

10. Results: Wavefront analysis and HOAs
Coma significantly increased only in the WFG-LASIK group, which is a known phenomenon¹
Trefoil had a significant decrease in the WFG-PRK group by a factor of 0.72 (Figure 3).
If there is any significance to this finding, it has yet to be described
¹Schallhorn SC, Farjo AA, Huang D, Boxer Wachler BS, Trattler WB, Tanzer DJ, Majmudar Pa, Sugar A, American Academy of Ophthalmology. Wavefront-guided LASIK for the correction of primary myopia and astigmatism. Ophthalmology. 2008;115:

11. Discussion It is important to mention limitations to this study
203 eyes were enrolled and 118 eyes (58%) were available for analysis at 6 months. Some patients have not reached the 6 month follow up date during data collection. Some patients were lost to follow up , which is the limitation of prospective studies.
A decrease sample size runs the risk of masking minor differences such as refractive outcomes and contrast sensitivities.

12. Discussion
Wavefront-guided PRK and wavefront-guided LASIK were found to have similar efficacy, safety, and contrast sensitivity
However, this study demonstrated that wavefront-guided PRK induced statistically less HOA than wavefront-guided LASIK at 6 months