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S.W. Wintch, D. Zhao, I.V. Ermakov, R.W. McClane, W. Gellermann, P.S. Bernstein; A Double Blind, Placebo Controlled, Lutein Supplementation Study Evaluating Two Macular Carotenoid Measurement Methods: Resonance Raman Spectroscopy and Heterochromatic Flicker Photometry . Invest. Ophthalmol. Vis. Sci. 2003;44(13):1744.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Two xanthophyll carotenoid pigments, lutein and zeaxanthin, are concentrated in the human macula where they may play a protective role against age-related macular degeneration (AMD), the leading cause of blindness in the elderly. Several noninvasive optical techniques have been proposed to quantify these macular pigments, but they have substantial methodological differences. This study compares two such methods: resonance Raman spectroscopy (RRS) and heterochromatic flicker photometry (HFP). Methods: RRS is an objective optical method in which argon laser light resonantly excites the macular carotenoids which then backscatter light to be collected and analyzed by a Raman spectrograph. HFP is a subjective psychophysical technique involving intensity matching of blue and green light at foveal and parafoveal areas. The macular pigment levels of 20 healthy subjects age 19 to 61 were quantified using the above two methods over a five-month period. Nine subjects were supplemented with 20 mg of lutein/day; eleven subjects took placeboes. Results: RRS and HFP correlated significantly throughout the test period (Corr.Coeff = 0.362, p = 0.0218). RRS showed significant rises in macular pigment after lutein supplementation (p = 0.046); HFP showed no such rise (p = 0.241). The placebo group remained unchanged during the test period (p-values for HFP, RRS and serum lutein levels: 0.689, 0.518, 0.828 respectively). RRS intrasession and intersession measurements were more repeatable than those of HFP. Neither method correlated significantly with serum levels of lutein. Conclusions: RRS is a specific and sensitive method for measuring macular pigment levels that in our hands is more precise and repeatable than HFP. As an objective method, RRS is reliable even in individuals with significant macular pathology, and we have previously shown with RRS that macular carotenoid levels are significantly lower in AMD eyes relative to age-matched controls (Ophthalmology 2002;109:1780-1787). The ability to raise ocular lutein levels in healthy eyes encourages further study into whether similar rises would occur in AMD eyes.
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