The influence of chromatic aberration on the static accommodative response

Previous measurements of static accommodation have consistently shown steady state errors over most of the range; the response lags below the stimulus and, at low levels, the response leads the stimulus. A series of experiments is presented in which the longitudinal and, for the first time, transverse chromatic aberrations of the eye were varied and the resultant stimulus-response functions of accommodation were measured. The results show that the steady state error of accommodation is not influenced by manipulations of the magnitude or the direction of either longitudinal or transverse chromatic aberration. This indicates that a particular wavelength is not preferentially focussed on the retina as a function of stimulus level and supports the negative feedback theory of accommodation.