These two carotenoid pigments are predominantly found at the macula. They absorb blue light and are thought to reduce photochemical damage caused by short-wavelength light. They are also antioxidants and may reduce light-induced oxidative damage to the retina. The body obtains these pigments from the diet. Dietary supplementation (by eating dark green leafy vegetables, for example) has been reported to increase the levels of pigment in the macula. Several methods have been used to measure the levels of pigment in the macula – these include reflectometry, autofluorescence spectrometry, Ramon spectoscopy and heterochromatic flicker photometry. These pigments have been shown to decrease with age. In age-matched patients, levels of lutein and zeaxanthin are lower in patients with age-related macular degeneration (AMD) than in those without AMD. Levels of these pigment do not correlate with the severity or type of AMD, however.