The wave-front aberration of the human eye was measured for eight subjects
using a spatially resolved refractometer (a psychophysical ray-tracing test
). The eyes were undilated and presented with accommodative stimuli varying
from 0 to -6 diopters. Monochromatic wave-front aberrations lend to increa
se with increasing levels of accommodation, although there are substantial
individual variations in the actual change in the wave-front aberration. Wh
ile spherical aberration always decreased with increasing accommodation, it
did not change from positive to negative for every observer. The direction
and amount of change in fourth order aberrations varied between observers.
Aberrations with orders higher than fourth are at a minimum near the resti
ng state of accommodation. The accommodation induced change in wavefront ab
erration was not strongly related to the total amount of aberration in the
eight eyes studied. (C) 1999 Elsevier Science Ltd. All rights reserved.