CONTROL OF VISUAL ACCOMMODATION BY OPPONENT COLOR MECHANISMS

Title CONTROL OF VISUAL ACCOMMODATION BY OPPONENT COLOR MECHANISMS
Author, Co-Author Karan Aggarwala, Lawrence Stark, Kevin Jackson, Philip Kruger
Topic
Year
1995
Day
Saturday
Program Number
1:00 pm
Room
Grand Ballroom D
Affiliation
Abstract PURPOSE. Recent studies have confirmed the view that the longitudinal chromatic aberration (LCA) of the eye forms part of a substrate for the control of accommodation. These studies suggest that the effects of LCA and defocus are probably analyzed by color-opponent visual mechanisms, to produce a neural signal to drive accommodation. The purpose of the present study was to determine whether red-green (R-G) and blue-yellow (B-Y) opponent mechanisms contribute to the control of accommodation.

METHODS. A 4 cyc/deg white sinusoidal grating was spectrally filtered to produce either a desaturated yellow-black grating or a desaturated blue-black grating. The individual contrasts of the three phosphor components of the gratings were altered by a computer to simulate sinusoidal defocus either in the presence (chromatic) or in the absence of LCA (achromatic). The target was presented in open-loop so that the subject's accommodation did not influence target contrast. Three 40 sec trials were conducted for each of the 4 stimulus conditions, at a temporal frequency of 0.2 Hz. Spectral photometry in the peaks and the troughs of the chromatic gratings showed that CIE chromaticity coordinates moved along a red-green color direction for the yellow-black grating, and along a blue-green direction for the blue-black grating.

RESULTS. Subjects (color normals) accommodated in response to both chromatic simulations (R-G and B-Y), but did not respond to the achromatic simulations.

CONCLUSIONS. Both color-opponent mechanisms (red-green and blue yellow) analyze the effects of defocus in the presence of ocular longitudinal chromatic aberration, to produce a neural signal for the control of accommodation. The first author was supported by a post-doctoral fellowship from NEI (F32-EYO6403)
Affiliation of Co-Authors
Outline