Accommodation to stationary and moving targets

Purpose, To test the hypothesis that the contrast of spectral components of the retinal image specifies ocular focus and controls reflex accommodation, Methods, Eight subjects viewed a stationary target at 0, 2.5, and 5 D in a Badal optometer, with longitudinal chromatic aberration (LCA) normal and reversed and in monochromatic (550 nm) light, Accommodation was monitored continuously during 40-s trials, Subjects also viewed the grating target as it moved sinusoidally (1,5 to 2.5 D) at 0.2 Hz under the same three conditions. Results. Subjects accommodated relatively accurately at all distances in the normal condition; three subjects had difficulty accommodating in monochromatic light at 5 or 0 D, and seven subjects could not maintain focus with LCA reversed. The accommodative response differed significantly in the three chromatic conditions both for stationary and moving targets, Conclusions. Relative contrast of long-, middle-, and short-wavelength components of the retinal image specifies ocular focus and drives reflex accommodation.