Corneal Higher Order Aberrations After LASIK for High Myopia With a Fast Repetition Rate Excimer Laser, Optimized Ablation Profile, and Femtosecond Laser–assisted Flap

Abstract

To evaluate corneal higher order aberrations (HOAs) after LASIK for the correction of high myopia using a new generation of excimer laser (500-Hz repetition rate) and optimized ablation profiles. Retrospective consecutive study including 29 eyes from 17 patients (age range: 24 to 61 years) with high levels of myopia (spherical equivalent refraction ≥8.50 diopters). All cases underwent LASIK using the sixth-generation Amaris (SCHWIND eye-tech-solutions) excimer laser and flap creation with the IntraLase (Abbott Medical Optics) femtosecond laser. Postoperative changes in corneal HOAs and corneal asphericity were analyzed during 6-month follow-up. Significant improvement in uncorrected distance visual acuity and spherical equivalent was observed (P<.01). Corrected distance visual acuity did not change after surgery (P=.37). Significant increases in corneal root-mean-square (RMS) HOA, RMS spherical aberration (SA), and RMS coma were observed 6 months after surgery (P<.01). Corneal asphericity for the 4.5-mm (Q45) and 8-mm (Q8) corneal diameter also increased significantly during the postoperative period (P<.01). Significant correlations were found between postoperative RMS HOA and RMS SA and RMS coma (r(2)=0.375, P=0.000 and r(2)=0.596, P=.000, respectively). Linear regression analysis showed a significant relationship between postoperative Q45 and preoperative pachymetry and treatment optical zone (R(2)=0.24, P<.05). A correlation was also found between postoperative Q8 and preoperative sphere and treatment ablation zone (R(2)=0.459, P<.006). A significant induction of corneal HOAs still exists with the latest generation Schwind excimer laser. Linear regression analysis will help predict postoperative asphericity obtained when using LASIK for the correction of high myopia.