[Supervision].
Within the past year, the idea of supervision has been introduced and promoted in the media by the manufacturers of wavefront-guided excimer lasers for refractive surgery. The concept is related to the ability of obtaining supernormal visual acuity and contrast sensitivity by correction of higher order aberrations in the biological optics of the human eye. However, the ocular aberrations fluctuate continuously and dynamically over time with the functional state of several of the individual optical components, including: thickness of the tear film, size of the pupil, and the degree of lens accommodation. These temporal variations represent major obstacles for achieving aberration-free images. In addition, the central perception of ideal aberration-free images may be hindered by neuronal limitations in the retina and brain. So far, only a few patients have experienced an increase in best corrected visual acuity following wavefront-guided refractive surgery. Also in the first prospective clinical trials with myopic individuals, only modest differences in visual performance have been detected between wavefront-guided and conventional treatment. Thus, immediate expectations from the new technology should be tuned down; supervision is not waiting around the corner.