According to an article on the BBC website, carotenoid supplements—particularly lutein and zeaxanthin—could play an important role in supporting eye health. Carotenoids are pigments that give plants some of their vibrant colors and help protect our retinas from the damaging blue light of the sun. Scientists have found evidence that supplementing with some carotenoids may help reduce glare, improve visual performance, sharpen colors, enhance contrast, and increase recovery times and processing speed. Dietary intake of lutein and zeaxanthin has also been associated with a reduced risk of macular degeneration. There is even evidence that these supplements can benefit healthy individuals: one study found that healthy drivers taking lutein daily experienced improved contrast and glare sensitivity, while another study found that taking lutein daily helped with contrast sensitivity. Dr. John Nolan, whom the BBC interviewed for the article and who researches nutrition and eye health, says that carotenoid supplements take about 6 to 12 months to start working.

Source: BBC