Raman detection of human macular carotenoid pigments

Summary form only given. The authors have used resonance Raman scattering as a novel optical technique to measure the concentration of carotenoid pigments in the human retina. Using argon laser excitation they obtained two strong carotenoid resonance Raman signals from human retinal tissues at 1159 and 1525 wave numbers, respectively. The laser power levels are within the limits given by the ANSI standard for ocular exposure (2.7 J/cm/sup 2/), and the obtained signals are free of potentially interfering signals from other molecules in the retinal tissue. Of the approximately 10 carotenoid pigments found in normal human serum, the species lutein and zeaxanthin are concentrated in high amounts in the cells of the human macula, which is a /spl sim/5 mm diameter area of the retina in which the visual acuity is highest. These carotenoids give the macula a characteristic yellow coloration, and it is speculated that their absorption may function as filter to attenuate photochemical damage and/or image degradation under bright UV/blue light exposures. In addition, they are thought to act as free-radical scavenging antioxidants. Studies have shown that there may be a link between macular degenerative diseases, the leading cause of blindness in the elderly in the United States, and the presence or absence of the carotenoid molecules.