How should colors be chosen to code information in order to optimize performance for individuals with low vision? Optimal choice is complicated by the heterogeneity of color vision losses occurring among individuals with acquired and congenital color vision defects. Two guidelines often suggested are to choose contrasting colors and to maximize luminance contrast, but each of these recommendations neglects that specifications of contrast and luminance often vary from the norms in a visually impaired eye. The approach taken here begins with general properties of color vision loss in low vision and from these derives principles to guide choices to colors that would optimize contrast in spite of such visual losses.

Most color vision losses that occur with visual impairment can be described in terms of a combination of the following general types of loss: 1) contrast sensitivity loss, 2) saturation discrimination loss, 3) wavelength discrimination loss and 4) luminosity loss at one or both extremes of the spectrum. Given these types of loss, a set of six qualitative recommendations is derived for choosing pairs of colors that if followed would minimize the likelihood of using color contrasts that are indiscriminable for individuals with low vision. The guidelines are designed to result in choices of color contrasts for which the residual luminance contrast will be maximized even when an individual has lost the ability to discriminate the chromatic component in the pair.

It is hoped that these recommendations will be of value to designers and architects who wish their products and environments to be accessible to individuals with low vision.