Abstract
Abstract: :
Purpose: The LUXEA study is a prospective, single–centered, randomized, placebo–controlled, one year pilot supplementation trial to investigate changes in macular pigment optical density (MPOD) following repeated dosing of zeaxanthin (OPTISHARPTM), lutein or their combination in healthy volunteers. Methods: Peak MPOD was measured relative to 5º eccentricity either by reflectance and autofluorescence using a Scanning Laser Ophthalmoscope or by heterochromatic flicker photometry (HCFP). Luminances at flicker null matches derived by HCFP for central and eccentric (5º) locations were independently evaluated. Of 126 subjects initially screened, 92 fulfilled the entry criteria and were randomized to four treatment groups: Lutein (L, n=23), Zeaxanthin (Z, n=23), Combination (C=L+Z, n=23) and Placebo (P, n=23). MPOD [(left+right eye)/2] was measured every month, plotted against visit number and the area under this curve (AUC) was calculated. To account for different lengths of follow–up, the AUC was normalized by dividing by the number of available measurements. In addition, the Generalized Estimating Equations (GEE) method was used to analyze correlated response variables. This method uses information from both eyes and corrects for unequal numbers of observations per subject, caused by missing values and/or by different lengths of follow–up. Results: Compared to the P group, supplementation with L lead to a statistically significant (p=0.035) overall MPOD increase of 13% as measured with HCFP. The respective values for reflectance and autofluorescence were 3% and 9%. A borderline significant increase (p=0.066) of 12% was seen for the C group. The situation for the Z group was different. The luminances of central and eccentric flicker matches derived from HCFP in this group rose both in parallel by approximately 8% during 6–12 months. This parallel increase was observed only in the Z group and may have obscured the detection of MPOD increases by any method. Consequently, if the pre–supplementation eccentric luminance had been used to calculate MPOD from the actual central luminances at subsequent visits, an increase of about 11% would have been computed. Conclusions: Supplementation with daily amounts of 10 or 20 mg L per day over periods of 6 to 12 months results in statistically significant but small increases of MPOD. The MPOD response to supplementation with Z is different, and may be explained by a more wide–spread retinal deposition of this carotenoid.
Keywords: macular pigment • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled • carotenoids/carotenoid binding proteins