Lutein is a carotenoid structure similar to pre-vitamin A (β-carotene) and involved in eye health. Lutein is an antioxidant to protect the macula from potentially damaging forms of ultraviolet light. Consequently, lutein is believed by many experts assist in prevention against age-related macular degeneration (the leading cause of blindness in older adults). Lutein also filters the high-energy, blue wavelengths of light from the visible. light spectrum by as much as 90%. Blue light, in both indoor lighting and sunlight, is believed to induce oxidative stress and possible free-radical damage in human organs exposed to light, such as the eyes ans skin. Blue light is not the same as the commonly known ultraviolet A and ultraviolet B wavelengths of the invisible spectrum.