The principal objective of the proposed studies is to elucidate the role of macular pigment in maintaining the functional integrity of the central retina. Specifically, our primary concern is with the purported protective effect of macular pigment and the extent to which the in situ density of this pigment influences the onset and progession of maculopathies in the human retina. The present proposal presents a series of experimental procedures by which to examine the hypothesized protective effect of the macular pigment (1) in normal age-related macular changes and (2) in maculopathies. Our pilot study that revealed an age-related reduction of macular pigment in human subjects will be expanded. The macular pigment decline in a normal population will be compared to the loss of foveal cone pigment density with age. The decline of cone pigment density across the fovea will be compared to macular pigment distribution. If macular pigment protects the cones, then the central fovea which has more macular pigment per retinal area should have less proportional decline with age compared to the parafovea. The influence of iris color on the amount of macular pigment present in an individual will be examined. In patients who are at risk of developing bull's eye macular lesions, the extent of possible protection provided by macular pigment with be examined. The amount and spatial distribution of macular pigment will be measured in patients at various stages of maculopathy and compared with age-similar normal subjects. In these patients, the amount and spatial distribution of the macular pigment will be compared with the foveal cone visual pigment. These dta will indicate whether the retention of foveal cone pigment in these patients is proportional to the density of macular pigment. An alternative explanation of the development of macular lesions that will be test is that mellanin under the macular pigment is spared, which may in turn contribute to the maintenance of the central fovea.
