title: Accommodation responses to stimuli in cone contrast space.
abstract: The aim was to identify the cone contributions and pathways for reflex accommodation. Twelve illumination conditions were used to test specified locations in cone-contrast space. Accommodation was monitored continuously in a Badal optometer while the grating stimulus (2.2 c/d sine-wave; 0.27 modulation) moved sinusoidally (0.195 Hz) towards and away from the eye from a mean position of 2.00 D (+/-1.00 D). Mean accommodation level and dynamic gain and phase at 0.195 Hz were calculated. Mean accommodation level varied significantly when the long- and middle-wavelength cone contrast ratio was altered in both the luminance and chromatic quadrants of cone-contrast space. This experiment indicates that L- and M-cones contribute to luminance and chromatic signals that produce the accommodation response, most likely through magno-cellular and parvo-cellular pathways, respectively. The L:M cone weighting to the luminance pathway that mediates accommodation is 1.63:1. The amplitude and direction of the response depends on changes in chromatic contrast and luminance contrast signals that result from longitudinal chromatic aberration and defocus of the image.
authors.affiliation: Schnurmacher Institute for Vision Research, State University of New York, State College of Optometry, 33 West 42nd Street, NY 10036-8003, USA. frucker@sunyopt.edu
authors.forename: Frances J
authors.initials: FJ
authors.lastname: Rucker
authors.forename: Philip B
authors.initials: PB
authors.lastname: Kruger
mesh_terms: D000065:Accommodation, Ocular / Q000502:physiology*; D003118:Color Perception / Q000502:physiology*; D015350:Contrast Sensitivity / Q000502:physiology*; D006801:Humans; D009907:Optometry / Q000379:methods; D010775:Photic Stimulation / Q000379:methods; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology