Is the human eye a perfect optic?

The aim of this work was to study the optical aberrations of higher order in a normal population and to answer the question on the optical quality of the human eye. Therefore, the optical aberrations of 130 eyes (90 individuals) have been measured by means of a wavefront measuring devices of Tscherning's-type. The pupil of each measured eye was dilated to at least 7 mm in diameter and wavefront sensing was performed with respect to the line of sight. The optical aberrations are expressed in terms of Zernike coefficients up to the 6th order, root-means-squared wavefront errors and critical pupil size. The main finding of this paper is that the `average eye' has only minimal wavefront errors indicating that the construction of the human eye, in principle, provides excellent optics exceeding the Marechal- criterion only by a factor of 2.1 (pupil diameter 5 mm). However, such minimal aberrations are achieved in only 6% of the individual eyes examined in this study. In conclusion, the `averaged human' eye has nearly a perfect optic, but the individual eye provides poor optical quality.