The long-term objectives of this study are to determine whether the macular pigments play a role in the etiology of human retinopathies, particularly those involving the macula. In several studies, it has been proposed that the pigments serve to protect the macula from photochemical damage. On theoretical grounds, this is certainly feasible, and there exists circumstantial evidence which supports this hypothesis.
The specific aims of this work are to compare the amount and composition of the macular pigments in donor eyes with and without age-related macular degeneration (AMD). Whether long-term exposure to excessive light is a risk factor for AMD is still unresolved; some studies have noted correlation. AMD affects the macular photoreceptors, retinal pigment epithelium, and Bruch's membrane. The macular pigments screen these tissues from the more damaging blue wavelengths, absorbing 20 to 80% of the light incident on the retina, depending on the amount of pigmentation. A person with very little macular pigment might therefore be at greater risk of developing AMD. Some preliminary data from our lab indicate that this may be the case and an extended, carefully controlled study is warranted. The carotenoids of which the macular pigments are composed will be extracted from different retinal locations in individual normal and age- matched AMD-afflicted donor eyes. They will be quantitatively analyzed at the individual stereoisomer level, using reversed- and normal-phase HPLC so that the amount, constitution and distribution of the pigments may be compared. Detailed ophthalmologists' reports will be of utmost importance and will, to the extent available, be obtained for each donor. A person diagnosed simply with AMD might have anything from a new drusen to neovascularization. Any correlation between prevalence of AMD and amount of macular pigmentation would raise immediate concerns about diet, the source of carotenoids in humans, and carotenoid metabolism and reactions, particularly in the eye. It would also raise another issue: Is low macular pigmentation a contributing factor in AMD or a result of the condition? Useful information will be obtained by similarly analyzing the carotenoids obtained from the donors' blood plasma and comparing them with those in the retina. A correlation between the amount of carotenoids in the retina and plasma carotenoid concentration in both normal and AMD donors might lend further support to the protection hypothesis.
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