In one embodiment, the invention provides a method of enhancing a subject's macular pigment optical density, the method comprising administering to the subject a pharmaceutically effective amount of one or more Xanthophyll carotenoids. Preferably, the Xanthophyll carotenoids are selected from the group consisting of lutein (L), zeaxanthin (Z), and meso-zeaxanthin (MZ), and enantiomers, metabolites, esters, pharmaceutically acceptable salts and derivatives thereof. In certain embodiments, the Xanthophyll carotenoids such as lutein (L), zeaxanthin (Z), and meso-zeaxanthin (MZ) are each in substantially pure enantiomeric form.
