Purpose.To assess the changes in higher-order (third through sixth) ocular wavefront aberrations produced by Corneal Refractive Therapy (CRT; Paragon Vision Sciences, Mesa, AZ).Methods.Eighteen eyes of nine myopic subjects were fit with CRT contact lenses. Baseline subjective spherical refraction ranged from −2.25 to −6.00 D (mean ± SD, −3.33 ± 1.26 D), and baseline logarithm of the minimum angle of resolution (logMAR) best-corrected visual acuity was −0.13 ± 0.06 (20/15 Snellen equivalent). Whole-eye ocular wavefront aberrations were measured using a previously validated Shack-Hartmann aberrometer. Measurements were taken at baseline and 1 month after treatment initiation. Nine measurements per dilated subject were taken and averaged. Zernike coefficients were used to calculate the third-, fourth-, fifth-, and sixth-order root-mean-square values for each eye for both 3- and 6-mm pupil sizes, and aberrations were averaged and compared with prior baseline readings.Results.The mean (±SD) myopia reduction was 3.08 ± 0.93 D, resulting in a subjective refraction of −0.22 ± 0.38 D after 1 month of lens wear. Both logMAR uncorrected visual acuity (−0.07 ± 0.18; 20/15−Snellen equivalent) and best-corrected visual acuity (−0.14 ± 0.09) after CRT wear were not significantly different from baseline logMAR best-corrected visual acuity (paired two-tailed t-test; p = 0.41 and 0.65, respectively). Whole-eye aberrations showed a statistically significant increase in higher-order aberrations for both 3-mm (factor of 2.66; p = 0.01) and 6-mm pupils (factor of 2.50; p = 0.005). Each individual higher-order aberration also increased, ranging from a factor of 2.01 to 3.20 for 3-mm pupil sizes and 2.52 to 2.98 for 6-mm pupil sizes. Spherical-like aberrations (S4 and S6) increased by a factor of 1.79 for 3-mm pupil sizes and 2.42 for 6-mm pupil sizes. The Zernike coefficient most affected by CRT was spherical aberration (Z40), which increased from 0.084 ± 0.16 to 0.39 ± 0.16 &mgr;m (p = 0.0002) for 6-mm pupils.Conclusions.Use of current CRT lenses for the reduction of myopia increased higher-order wavefront aberrations and spherical aberration (Z40) in particular.