Chromatic contrast sensitivity: the role of absolute threshold and gain constant in differences between the fovea and the periphery

Abstract

A model of foveal achromatic and chromatic sensitivity [Vision Res. 36, 1597 (1996)] was extended to the peripheral visual field. Threshold-versus-illuminance functions were analyzed to determine effects of eccentricity on absolute thresholds and gain constants of chromatic and luminance mechanisms. The resulting peripheral model successfully predicted peripheral contrast sensitivity as a function of wavelength, for both white and 500-nm backgrounds. We conclude that the short-wavelength-sensitive cone opponent mechanism may mediate thresholds in Sloan's notch in the normal periphery and that interpretation of reduced chromatic sensitivity in the periphery requires an explicit model of how eccentricity affects both the gain constant and the absolute threshold.

Short wavelength automated perimetry and tamoxifen use

“…Foveal SWS cone mediated sensitivities On theroretical grounds, 21 the SWAP sensitivities in the visual field periphery were expected to depend on at least three factors involving SWS cone mediated sensitivity: (1) the rate of sensitivity decline with increasing eccentricity, (2) the baseline sensitivity level-that is, the sensitivity level at yellow background illuminances too dim to induce appreciable sensitivity loss, and (3) an adaptation factor-that is, the degree of desensitisation induced by the yellow background for SWAP. For modelling purposes, the first of these three factors was represented by the reduction of SWAP sensitivity from the second to the third ring.…”

“…21 These determinants were assessed by relating SWS cone mediated sensitivities from the fovea and central portions of the visual field to SWAP sensitivities in the periphery. A multilinear regression model of peripheral SWAP sensitivities is presented in the second part of the Results section.…”

Responses of Primate Retinal Ganglion Cells to Perimetric Stimuli

“…41,44 This is because P cells are much more responsive to chromatic modulation than to luminance; therefore, if P cells mediated detection for the white luminance increments, the sensitivity difference between opponent and non-opponent mechanisms would be much larger. 45 However, this is not the case.…”

Contrasting Blue-on-Yellow with White-on-White Visual Fields: Roles of Visual Adaptation for Healthy Peri- or Postmenopausal Women Younger Than 70 Years of Age

“…Presently, there is only limited information concerning these types of comparisons. 39 The extent to which the results in this study would apply to other healthy populations is unknown. It is possible, for example, that adaptation properties would depend on retinal locus in a way that would invalidate or compromise the use of foveally based models for any of the following populations: men, young women (for whom there is cyclic hormonal change), postmenopausal women using hormone replacement, or the elderly (for whom the hill of vision steepens 6 ).…”