Wavefront sensors and scanning laser technology are enabling the correction of the aberrations of the eye. The effects of aberrations on visual performance are reviewed, and the theoretical limit of visual performance is predicted to understand the ultimate endpoint of these new technologies. A schematic eye model that incorporates diffraction, chromatic aberration, photopic response, the Stiles-Crawford effect, and pupil size is ray-traced to determine its limiting optical properties. These properties are compared to the detection requirements of the retina and brain to determine the theoretical limit of foveal vision. The theoretical limits on foveal vision are found to be between 20/12 and 20/5, depending on pupil diameter. It is concluded that emerging refractive surgery technologies may provide substantial increases in visual performance.