Abstract
New technologies for accurately measuring corneal shape and full eye aberrations are now available. An algorithm that uses these technologies to predict the amount of ablation needed to produce a corneal surface that optimally focuses light is developed. It is found that knowledge of the aberrations is far more important than knowledge of corneal shape. Neglect of corneal shape information introduces an error of less than approximately 0.05 µm in the optimal ablation depth. Neglect of the aberrations is a different story. Small changes in the aberration structure, such as going from the optimal ablation to a spherical ablation, introduce ablation changes of greater than 10 µm. It is argued that there are many occasions when less ablation can lead to improved image quality.