Carotenoids are molecules ubiquitous in nature that prevent cellular damage from the sun. In this clip, Bruce Ames explains that two carotenoids in the eye, lutein and zeaxanthin, are able to mitigate the harmful effects of singlet oxygen produced by sunlight. Deficiency of these two carotenoids leads to macular degeneration. He shares that he is currently writing a paper arguing that lutein and zeaxanthin should be considered vitamins because they are critical for long-term health of the eye.