PURPOSE: To define the magnitude of optical aberrations before and after LASIK. METHODS: A Custom Cornea® wavefront sensor (CCWS) was used to analyze 113 eyes prior to LASIK. 105 of these eyes then had LASIK surgery in two consecutive cohort groups with a nomogram change in between (71 eyes and 34 eyes respectively). Wavefront sensing was performed postoperatively at one week, one month, and three months. The total wavefront Root Mean Square (RMS) error and co-efficient amplitudes were determined. RESULTS: The dominant preoperative wavefront aberrations were spherical refractive error and astigmatism. The higher order aberrations were of lower magnitude with preoperative coma being dominant (0 - 0.0005μ RMS). Spherical equivalent had the next highest magnitude ranging from -0.0001μ to -0.0003μ RMS. Postoperative RMS error was found to be significantly higher for hyperopes than myopes (p<0.05). CONCLUSION: Wavefront sensing demonstrates an increase in higher order aberrations after LASIK with greater total RMS values seen in hyperopic versus myopic treatments. Change in refractive nomogram improves the RMS outcome, making wavefront sensing a potentially useful tool in nomogram development.