Wavefront-guided Versus Standard Laser in situ Keratomileusis in Myopia Using a 213 nm Wavelength Solid-state Laser: Comparison of Higher-order Aberrations.

Purpose: To assess the accuracy, efficacy, stability and safety of laser in situ keratomileusis (LASIK) for myopia and compare the pre- and post-operative changes in higher-order aberrations after wavefront-guided (WF) and standard (STD) LASIK done using the Pulzar Z1, a 213-nm wavelength solid-state laser, and determine their effects on visual acuity and refractive outcomes. Methods: This a retrospective case series composed of 80 eyes (40 patients) that had LASIK in an out-patient refractive surgery center in Manila, Philippines. Outcome measured were pre and post-operative manifest refraction spherical equivalent (MRSE), uncorrected distance visual acuity (UDVA), best-corrected distance visual acuity (CDVA), keratometry, root-mean-square (RMS) values, flap and ablation related complications. Results: The mean UDVA improved from 20/400 pre-operatively to 20/25 post-operatively. Thirty six of the 40 eyes (90%) treated with STD LASIK and 39 of the 40 eyes (97.5%) treated with WF LASIK had UDVA of 20/30 or better at 1 year post-operatively. There was a significant decrease in spherical equivalent manifest refraction post-operatively in all patients. The average spherical equivalent at 1 year is -0.43D±0.64. After twelve months of follow-up, 85.5% (34 out of the 40 eyes) of those who underwent STD LASIK and 77.5% (31 out of 40 eyes) who underwent WF LASIK had postoperative manifest refractive spherical equivalent (MRSE) of -1.0 to +1.0D. The mean difference in the attempted versus achieved refraction was not significant between the 2 groups (p = 0.32). At 12 months post-operatively, seven eyes (17.5%) gained 1 line in the WF-guided LASIK, while the rest of the eyes either showed no change in CDVA or lost 1-2 Snellen lines. The total RMS generally increased postoperatively for WF LASIK while decreased for STD LASIK, but the mean RMS difference from the pre- and post-operative values between the 2 groups were not statistically significant. None of the eyes developed flap complications during the follow-up period. Conclusion: Refractive surgery using the Pulzar Z1 213-nm wavelength solid-state laser is an effective and safe procedure in the treatment of myopia. Wavefront-guided LASIK offers no advantage over STD LASIK in improving higher-order aberrations and in achieving better visual and refractive outcomes.

Clinical Outcomes of LASIK Using a 213 nm Solid-State Laser System: 6-month Follow-up

PURPOSE: To present prospective clinical results of laser-assisted in situ keratomileusis (LASIK) using a solid-state laser system for the correction of mild to moderate myopia with or without astigmatism. METHODS: Thirty-eight eyes underwent LASIK using a 213 nm solid-state laser (Pulzar Z1trade mark, CustomVistrade mark, Australia). Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), refractive errors, higher order aberrations (HOA) and contrast sensitivity were evaluated preoperatively and postoperatively. RESULTS: The preoperative and postoperative mean spherical and cylindrical refractive errors were -3.27+/-0.85D, +1.04+/-0.69D, -0.36+/-0.7D and +0.14+/-0.2D, respectively. UCVA over 20/25 was obtained in 27 eyes (93%). A result within 1.00D of the desired correction was achieved in 90% of the eyes. There were no decreases in BCVA within the study group. The preoperative and postoperative root-mean-square of HOA at 3 months were 0.196+/-0.092 microm and 0.326+/-0.107 microm respectively. The preoperative and postoperative contrast sensitivity values were similar. CONCLUSIONS: The clinical outcomes of LASIK using a solid-state laser system were comparable to the conventional refractive surgery in mild to moderate myopia. The 213 nm solid state laser may be an alternative option for refractive surgery.

Influence of Surface Fluid during Photorefractive Keratectomy Using a 213-nm Solid-State Laser

PURPOSE: To investigate the effect of surface fluid on the ablation rate and efficacy of 213-nm solid-state laser during photorefractive keratectomy (PRK). METHODS: Twelve rabbits (24 eyes) underwent myopic PRK for the correction of 10 diopters using 213-nm solid-state laser. Photoablation was performed with removal of corneal surface fluid using the Weckcel(R) sponge every 5 seconds in one eye and without removal of corneal surface fluid in the control eye. The mean central corneal thickness (CCT) was evaluated preoperatively, and at 1 week, 4 weeks postoperatively. RESULTS: The mean CCT of group 1 (with removal of corneal surface fluid) were 361.3+/-13.9 micrometer preoperatively and 321.4+/-18.5 micrometer at 4 weeks postoperatively. The mean CCT of group 2 (without removal of surface fluid) were 358.7+/-8.9 micrometer preoperatively and 338.4+/-12.0 micrometer at 4 weeks postoperatively. The mean ablation depths were 39.8+/-7.4 micrometer in group 1 and 20.3+/-5.8 micrometer in group 2 at 4 weeks postoperatively p<0.05). CONCLUSIONS: Induced corneal surface fluid during PRK may influence the ablation efficacy and accuracy of solid-state laser. This result should be considered in clinical trialswith 213-nm solid-state laser, especially in high myopes.