Retrospective Analysis of the Post-Operative Changes in Higher-Order Aberrations: A Comparison of the WaveLight EX500 to the VISX S4 Laser in Refractive Surgery

Abstract

Introduction: In an attempt to maximize treatment outcomes, refractive surgery techniques are being directed toward customized ablations to correct not only lower-order aberrations but also higher-order aberrations specific to the individual eye. Measurement of the entirety of ocular aberrations is the most definitive means to establish the true effect of refractive surgery on image quality and visual performance. Whether or not there is a statistically significant difference in induced higher-order corneal aberrations between the VISX Star S4 (Abbott Medical Optics, Santa Ana, California) and the WaveLight EX500 (Alcon, Fort Worth, Texas) lasers was examined. Methods: A retrospective analysis was performed to investigate the difference in root-mean-square (RMS) value of the higher-order corneal aberrations postoperatively between two currently available laser platforms, the VISX Star S4 and the WaveLight EX500 lasers. The RMS is a compilation of higher-order corneal aberrations. Data from 240 total eyes of active duty military or Department of Defense beneficiaries who completed photorefractive keratectomy (PRK) or laser in situ keratomileusis (LASIK) refractive surgery at the Wilford Hall Ambulatory Surgical Center Joint Warfighter Refractive Surgery Center were examined. Using SPSS statistics software (IBM Corp., Armonk, New York), the mean changes in RMS values between the two lasers and refractive surgery procedures were determined. A Student t test was performed to compare the RMS of the higher-order aberrations of the subjects' corneas from the lasers being studied. A regression analysis was performed to adjust for preoperative spherical equivalent. The study and a waiver of informed consent have been approved by the Clinical Research Division of the 59th Medical Wing Institutional Review Board (Protocol Number: 20150093H). Results: The mean change in RMS value for PRK using the VISX laser was 0.00122, with a standard deviation of 0.02583. The mean change in RMS value for PRK using the WaveLight EX500 laser was 0.004323, with a standard deviation of 0.02916. The mean change in RMS value for LASIK using the VISX laser was 0.00841, with a standard deviation of 0.03011. The mean change in RMS value for LASIK using the WaveLight EX500 laser was 0.0174, with a standard deviation of 0.02417. When comparing the two lasers for PRK and LASIK procedures, the p values were 0.431 and 0.295, respectively. Conclusion: The results of this study suggest no statistically significant difference concerning induced higher-order aberrations between the two laser platforms for either LASIK or PRK. Overall, the VISX laser did have consistently lower induced higher-order aberrations postoperatively, but this did not reach statistical significance. It is likely the statistical significance of this study was hindered by the power, given the relatively small sample size. Additional limitations of the study include its design, being a retrospective analysis, and the generalizability of the study, as the Department of Defens...

Functional optical zone after wavefront-optimized versus wavefront-guided laser in situ keratomileusis

“…In our study, postoperative RMS for HOAs and spherical aberration Zernike coefficient (Z40) showed no significant differences between the two groups. This was also observed previously by Roe and Manche [ 23 ], He et al [ 17 ], Reed et al [ 32 ], and Mahmoud et al [ 30 ]. However, Moshirfar et al [ 4 ], Khalifa et al [ 21 ], and Ghoneim et al [ 31 ] found that the level of induced HOAs was significantly higher in the WFO group than in the WFG group, which could be attributed to their use of high-resolution aberrometer measurements to define WFG ablation profiles [ 4 , 21 , 31 ].…”

Corneal Epithelial Remodeling After Femtosecond Laser-Assisted in Situ Keratomileusis Combined with Intraoperative Accelerated Corneal Collagen Crosslinking for Myopia: A Retrospective Study

“…LASIK procedures using Wavelight FS200 (Alcon Laboratories, Fort Worth, TX, USA) femtosecond laser combined with VISX Star S4 (Abbott Medical Optics, Santa Ana, CA, USA) excimer laser platforms provide predictable, e cacious, and safe postoperative outcomes [9,10]. The VISX Star S4 excimer laser system's ablation software has a tendency toward central islands (CI) formation [11], and the effect of CI formation on visual rehabilitation, safety, and stability after LASIK Xtra (energy, 2.7 J/cm 2 ; irradiance, 30 mW/cm 2 ) has not been fully elucidated.…”