Everyone has varying amounts of lutein. According to a recent report, it is not genetic factors, but the dietary consumption and absorption of lutein that determines the density of protective yellow macular pigment at the back of the eyes. Yellow lutein, by virtue of its location in front of the central photoreceptors, protects the rods, cones, and retinal pigment epithelial layer from oxidative damage caused by unfiltered sunlight. The density of brown melanin in the iris and retina is genetically-determined and may be a factor in protecting against macular disease. Melanin appears to be a secondary defense against oxidative damage caused by blue light.
Some experts believe that lutein acts like a pair of sunglasses.
It protects the macula from the oxidative effects of ultraviolet light. The more unfiltered sunlight that reaches your retina, the more lutein is used up defending your delicate retinal tissues. This is why wearing ultraviolet light protection is so important. It may help to preserve the lutein in your eye. It is important to remember that contact lenses and eyeglasses, unless specifically marked, do not filter out the potentially harmful ultraviolet rays of sunlight.