Lutein and zeaxanthin have been well researched as being essential nutrients in both helping to prevent the onset of macular degeneration as well as helping protect vision for those with macular degeneration. People with macular degeneration have been shown to have reduced macular pigment optical density (MPOD).
Meso-zeaxanthin is the third major carotenoid found in macular pigment (along with lutein and zeaxanthin).
A new study showed that supplementation of gelcaps containing mostly mesozeaxanthin (along with some lutein and zeaxanthin) resulted in increased blood serum levels of all three carotenoids during the 120 day study supplementation period, and was effective in increasing macular pigment optical density (MPOD).
Ref: Florida International University (Nutr Metab. 2007;4:12)
Another study substantiates the value of supplementing with mesozeaxanthin.
Nutrition & Metabolism 2007, 4:12
See more information on macular degeneration and mesozeaxanthin.