Determination of human cone pigment density difference spectra in spatially resolved regions of the fovea.

A new method was developed to measure spectrally and spatially resolved cone pigment optical density difference in normal human subjects. Using digitized television images of human retinas scanned before and after bleaching the cone pigments with a bright light, unique high-resolution images of cone pigment density difference were produced. The spectral peak density difference within the fovea was found to be at 560 nm. These measurements demonstrate a decrease in cone pigment optical density difference with increased distance from the subject's central fixation point in the fovea. The cone pigment density difference was asymmetrically distributed in the fovea with higher amounts on the nasal side.