To assess safety, efficacy, predictability, stability, and change in aberratio ns after wavefront-guided LASIK for myopia and myopic astigmatism. Prospective, nonrandomized, self-controlled trial. Wavefront-guided LASIK was performed in 97 eyes in a 1-year trial. Treated eyes had a mean subjective manifest spheric al equivalent (SE) of -5.22±2.07 diopters (D), with a range of -0.25 to -9.0 0 D of myopia and 0 to -3.25 D of astigmatism. After a microkeratome cut, a wav efront-based excimer ablation (Zyoptix 3.1) was performed. The full treatment t o achieve emmetropia of an early nomogram provided by the system manufacturer wa s used in all procedures. Safety, efficacy, predictability, and stability were e valuated at 1, 3, and 12 months postoperatively. Wavefront changes of higher ord er aberrations (HOAs) at 1 year were determined for pupil sizes of 3.5 and 6 mm. At 1 year postoperatively, uncorrected visual acuity (VA) was 20/20 or better i n 83%of the eyes, and 20/40 or better in 98%. The mean subjective manifest SE at 1 year was -0.25±0.43 D; it was within 0.50 D in 77%and within 1.0 D in 95 %. No eye lost < 2 lines of best spectacle corrected VA (BSCVA) at 1 year post operatively; 40 eyes gained 1 line of BSCVA, and 5 eyes gained 2 lines. The tota l HOA root meansquare (RMS) increased on average by a factor of 1.23±0.57 with a 3.5-mm pupil; for the 6 mm pupil, the increase factor was 1.52±0.36. No chan ge or reduction in the total HOA RMS was observed in 45.5%of the eyes for a 3.5 -mm pupil and in 20.6%for a 6-mm pupil. There was a significant increase of p rimary spherical aberration (Z 4,0) by a factor of 4.11±10.17 for 3.5-mm pupil s and 4.31±6.76 for 6-mm pupils. Wavefront-guided LASIK using Zyoptix 3.1 is an effective and safe procedure for the treatment of myopia and myopic astigmati sm. Although in close to half of the eyes HOAs could be reduced, there was still undercorrection and induction of HOAs with the algorithm employed. To assess safety, efficacy, predictability, stability, and change in aberration ns after wavefront-guided LASIK for myopia and myopic astigmatism. Prospective, nonrandomized, self-controlled trial. Wavefront-guided LASIK was performed in 97 eyes in a 1-year trial Treated eyes had a mean subjective manifest spheric al equivalent (SE) of -5.22 ± 2.07 diopters (D) with a range of -0.25 to -9.0 0 D of myopia and 0 to -3.25 D of astigmatism. After a microkeratome cut The full treatment to achieve emmetropia of an early nomogram provided by the system manufacturer wa s used in all procedures. Safety, efficacy, predictability, and stability were evaluated at 1 , 3, and 12 months postoperatively. Wavefront changes of higher aberration (HOAs) at 1 year were determined for pupil sizes of 3.5 and 6 mm. At 1 year postoperatively, uncorrected visual acuity (VA) was 20/20 or better in 83% of the eyes, and 20/40 or better in 9 8%. The mean subjective manifest SE at 1 year was -0.25 ± 0.43 D; it was within 0.50 D in 77% and within 1.0 D in 95%. No eye lost <2 lines of best spectacle corrected VA (BSCVA) at 1 The tota l HOA root mean square (RMS) increased on average by a factor of 1.23 ± 0.57 with a 3.5-mm pupil; for the 6 mm pupil , the increase factor was 1.52 ± 0.36. No chan ge or reduction in the total HOA RMS was observed in 45.5% of the eyes for a 3.5-mm pupil and in 20.6% for a 6-mm pupil. There was a significant increase of P rimary spherical aberration (Z 4,0) by a factor of 4.11 ± 10.17 for 3.5-mm pupils and 4.31 ± 6.76 for 6-mm pupils. Wavefront-guided LASIK using Zyoptix 3.1 is an effective and safe procedure for the treatment of Although in close to half of the eyes HOAs could be reduced, there was still undercorrection and induction of HOAs with the algorithm employed.