In aberrometry, optical system of an eye plays a twofold role - as an object of measurement and as a part of aberrometer.
It means that the aberrations to be measured are themselves the source of measurement errors. Simulation with ZEMAX
demonstrated error dependencies for all Zernike components having an axial asymmetry. To compensate for the induced
errors, the ray tracing procedure is proposed to be modified in a way to individually tilt the probing beam in each point
where it enters the eye and to make it to cross the visual axis on the retina. One iteration makes the error less by about
one order. Optical layout is proposed containing two sets of two-coordinate acousto-optic deflectors, the first one
changing the height of the beam and the second one directing the laser beam into the same point that was designated in
the initial measurement.