Elliptical versus circular flap configuration in myopic eyes undergoing femtosecond laser in situ keratomileusis surgery: A contralateral eye study

Abstract

Purpose: To study whether a customized elliptical flap configuration offers any visual, refractive, or biomechanical advantage over the 'conventional' circular flaps in patients undergoing myopic laser in situ keratomileusis (LASIK). Methods: A prospective interventional contralateral eye study was undertaken enrolling 290 eyes of 145 myopic patients (≤-6.0D) undergoing LASIK, wherein the corneal flap was created in one eye using a customized elliptical flap configuration versus a conventional circular flap configuration in the other eye. Postoperatively, we compared the visual outcome, change in higher-order aberrations, corneal asphericity, and corneal biomechanics. Results: The visual outcomes, including higher-order aberrations, were comparable between the two groups. Changes in spherical aberration (mean: 0.234-0.331 versus 0.234-0.42; P = 0.644), corneal asphericity (-0.32-0.34 versus - 0.34-0.45; P = 0.42), corneal hysteresis (9.35-7.33 versus 9.4-6.71, P = 0.489), corneal resistance factor (9.71-7.40 versus 10.38-6.9, P = 0.181) were comparable between the elliptical and circular groups, respectively. Conclusion: We evaluated the usefulness of a customized elliptical flap configuration for performing LASIK surgery. Our data suggests that elliptical flaps may be associated with superior visual and biomechanical performance compared to circular flaps. This is certainly relevant in eyes with 'borderline' pre-LASIK profile to improve patient satisfaction and safety after surgery.