Comparative evaluation of higher-order aberrations and corneal asphericity between wavefront-guided and aspheric LASIK for myopia.

Abstract

To compare visual outcome, higher-order aberrations, and corneal asphericity (Q value) between wavefront-guided and aspheric LASIK for myopia and myopic astigmatism. Forty patients were randomly selected to receive wavefront-guided LASIK (wavefront-guided group) or aspheric LASIK (aspheric group) (40 eyes of 20 patients in each group) using the Technolas 217z excimer laser platform (Bausch & Lomb, Rochester, NY). Flaps were created using the Zyoptix XP microkeratome (Bausch & Lomb). Preoperative and postoperative evaluation included uncorrected distance visual acuity (UDVA), corneal topography, wavefront aberrometry, and contrast sensitivity. Minimum follow-up period was 6 months. At 6 months postoperatively, the aspheric group had significantly better UDVA (logMAR 0.04 ± 0.04 [Snellen 20/16] [range: -0.079 to 0.000]) and lower mean residual spherical error (+0.10 ± 0.52 diopters [D] [range: -1.12 to 1.25 D]) than the wavefront-guided group (logMAR UDVA 0.00 ± 0.07 [range: -0.079 to 0.176]; MRSE -0.35 ± 0.47 D [range: -1.5 to 0.62 D]) (P = .003 and < .001, respectively). Mean change in higher-order aberration root mean square at 6 months postoperatively (6-mm pupil) was 0.16 ± 0.17 µm after aspheric LASIK and 0.27 ± 0.28 µm after wavefront-guided LASIK (P = .02). Aspheric LASIK induced minimal change in spherical aberrations postoperatively (0.03 ± 0.12 µm, P = .09), unlike wavefront-guided LASIK (0.23 ± 0.17 µm, P < .01). Change in Q value was significantly less in the aspheric group (0.53 ± 0.31) than the wavefront-guided group (0.91 ± 0.30) (P < .01). The aspheric group had significant improvement in contrast sensitivity at all spatial frequencies (P < .01), whereas the wavefront-guided group showed a slight decrease at higher spatial frequency (18 cycles per degree). Aspheric LASIK induced significantly less change in higher-order aberrations and maintained corneal asphericity better than wavefront-guided LASIK. The visual outcome and contrast sensitivity was better in the aspheric group at 6 months postoperatively.