Macular pigment difference spectrum from sensitivity measures of a single cone mechanism

We have obtained the difference spectrum for the macular pigment by comparing the spectral sensitivity of the "green-sensitive" or G cone mechanism in the foveal and parafoveal region. The method overcomes objections to previous attempts to obtain a difference spectrum from the spectral sensitivities by isolating a single receptor mechanism; it also provides a relatively easy approach for obtaining a reliable measure of the optical density of the macular pigment for individual subjects. Our results using this method suggest a higher optical density for the macular pigment than that obtained from data where more than one cone type influenced the difference spectrum.