Abstract
Introduction In cone-based color space, axes can be determined that selectively modulate different cone or cone-opponent systems. However, retinal inhomogeneities make it difficult to apply foveal-based determinations of these axes to large-field or peripheral stimuli. There are several methods for determining an individual or a local isoluminant plane that can partially solve this problem. What remains is the problem of locating specific axes (e.g. the S-cone isolating or tritan axis) within this plane as these are also affected by factors such as macular pigment distribution. There are various techniques for determining an individual's tritan line, including minimally distinct border and transient tritanopia that have traditionally been applied to foveal viewing. We present here a method for locally determining the tritan axis across the visual field using a modification of the minimally distinct border procedure. Methods Ten subjects (five female, mean age 26) with normal color vision viewed slowly rotating, circular, bipartite patches presented at five retinal eccentricities. These fields comprised two colors falling along an axis within an isoluminant plane in color space. Subjects rotated the color axes in color space until the border between the two chromaticities was minimally distinct. This was done for each of five retinal eccentricities, and repeated three times. Results Calculations of the location of the tritan axis with and without macular pigment accounted for most of the results from the minimally distinct border judgments. Interestingly, the magnitude of rotation required for a minimally distinct border was greater than predicted. Our modification of the minimally distinct border task seems to be a convenient and rapid method for determining an individual's tritan line (and consequently, macular pigment density) across the visual field.
Meeting abstract presented at VSS 2014