Line of sight and alternative representations of aberrations of the eye.

Several methods for representing pupil plane aberrations based on wavefront height, slope, and curvature are discussed. The choice of reference axis and reference surface is shown to strongly affect the appearance of the representation. Special attention will be paid to the use of the line of sight (the line from the fixation point to the center of the pupil) as the reference axis. We show that the line of sight is ambiguous and does not determine the amount of prism in the wavefront.