Effect of scanning patterns on the results of femtosecond laser lenticule extraction refractive surgery

PURPOSE: To report the clinical results of refractive lenticule extraction using a femtosecond laser and describe the effect of scanning patterns on the results. SETTING: Private laser center, Vadodara, India. DESIGN: Prospective clinical study. METHODS: The Visumax femtosecond laser system was used to perform lenticule extraction to treat refractive errors using 2 scanning trajectories. The laser was used to cut a refractive lenticule intrastromally to correct myopia or myopic astigmatism. The lenticule was then physically extracted from the stroma. In scanning pattern A, the laser scanned from the center out and the periphery in while the 2 surfaces of the lenticule were cut. In scan pattern B, the laser scanned from the periphery in and the center out. Outcome measures were corrected and uncorrected distance visual acuities and manifest refraction during a 6-month follow-up. Differences between the 2 scanning patterns were also analyzed. RESULTS: The study comprised 329 eyes of 173 patients. One week postoperatively, there were statistically significant differences in refractive outcomes (P=.03), safety (P<.01), and efficacy (P<.01), between the 2 scanning-pattern groups. At 6 months, there were no significant differences. CONCLUSIONS: Early visual recovery and refractive outcomes after femtosecond lenticule extraction were affected by the scanning trajectory of the laser. A trajectory that scanned from the periphery to the center and the center to the periphery to cut the 2 lenticule surfaces had a positive effect on visual recovery. Financial Disclosure: Neither author has a financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes. J Cataract Refract Surg 2011; 37:1636-1647 (C) 2011 ASCRS and ESCRS