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SW Wintch, D-Y Zhao, IV Ermakov, RW McClane, W Gellermann, PS Bernstein; Evaluation of Two Macular Carotenoid Measurement Methods: Resonance Raman Spectroscopy and Heterochromatic Flicker Photometry . Invest. Ophthalmol. Vis. Sci. 2002;43(13):2551.
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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; it involves argon laser light resonantly exciting the carotenoids in the macula 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 sites. The macular pigment levels of 22 healthy subjects age 20 to 61 were quantified using the above two methods over three consecutive sessions. Results:RRS and HFP correlate significantly (P<0.002), and both methods show a decline with age, although it is more obvious in RRS (R=0.575) relative to HFP (R=0.307). RRS intrasession and intersession measurements are more repeatable than those of HFP. Neither method correlates significantly with serum levels of lutein and zeaxanthin. Conclusion:RRS is a specific and sensitive method for measuring macular pigment levels that in our hands is more precise and repeatable than HFP. Our findings confirm earlier results that macular pigment levels decrease with age. 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 (see ARVO 2001 abstract number 674).
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