Investigation of simulated lens yellowing, opacification and refractive error on Resonance Raman Spectroscopy.

Abstract

Abstract: : Purpose:To separately investigate the impact of simulated age–related lens yellowing, opacification and refractive error on macular carotenoid status using Resonance Raman Spectroscopy(RRS). Methods:Two healthy young subjects with clear media underwent Raman spectroscopy under the following conditions: Age–related lens yellowing was simulated using seven broad–band yellow filters with transmittance at 488nm ranging from 0.54–0.9; cataract was simulated using 5 white opacity filters the transmittance of which ranged from 0.86–0.42, each of which reduced peak Contrast Sensitivity by approx 0.1 log units over the previous filter. Refractive blur was achieved using soft contact lenses ranging from +1.00 to +6.00DS. Results:The Raman signal declined steadily to a value of 50% using the densest yellow filter. The white opacity filters produced an approximately linear reduction of 25% per filter. Refractive error resulted in a slight improvement in Raman count up to a value of +2.00DS followed by a decline thereafter. Conclusions:These results imply that lens opacification has an influence on the Raman signal and suggest that studies using this technology to estimate macular pigment levels in older populations should take into account the status of the lens.

Keywords: macular pigment • carotenoids/carotenoid binding proteins • clinical (human) or epidemiologic studies: systems/equipment/techniques