The association between femtosecond laser flap parameters and ocular aberrations after uncomplicated custom myopic LASIK

Background: To investigate the association between femtosecond laser flap parameters, uncorrected distance visual acuity, and higher-order aberrations (HOA) after customized myopic LASIK. Methods: Retrospective review of the charts of patients who underwent uncomplicated wavefront-guided customized myopic LASIK with flap creation using the femtosecond laser. Patients were stratified by intended flap thickness, and the change in HOA from preoperative to 3 months postoperative was compared. Multivariate linear models were performed to assess the association between calculated flap thickness, intended flap diameter, HOA, and uncorrected visual acuity. Results: One hundred seventy-one eyes of 171 patients were included. There was no statistically significant difference in the induction of HOA between eyes with thin (90 μm) or thick (100 or 110 μm) intended flaps. In a multivariate model, the level of myopic correction was highly associated with the induction of total HOA, coma, and spherical aberration. There was no correlation between calculated flap thickness, uncorrected visual acuity, or HOAs. Intended flap diameter was not associated with coma or spherical aberration, but larger flap diameter was associated with better uncorrected visual acuity. Conclusions: Femtosecond laser flap thickness in the range of 90-110 μm was not associated with uncorrected visual acuity or the induction of HOA after uncomplicated customized myopic LASIK. The level of myopic correction was the largest determinant of the induction of HOA.