The macular pigment is a collective term for the carotenoids Lutein, Zeaxanthin and Meso-Zeaxanthin, located mainly at the macula prior to the photoreceptor layer. Its origin is purely dietary and can be found mainly in leafy vegetables. The macular pigment is believed to have two distinct roles: on  the one hand it serves as an optical filter absorbing the shorter part of the visible spectrum, i.e. blue light, that can cause photochemical damage to the retina; on the other hand it is a powerful anti-oxidant quenching harmful free radicals present at the retina.