BACKGROUND: Increased consumption of lutein and zeaxanthin has been shown to increase macular pigment optical density (MPOD) in some individuals. Most interventions either obtained infrequent measures of MPOD or measured MPOD at a single retinal locus. PURPOSE: The aim of this study was to measure acute changes in MPOD at four retinal loci during lutein intervention. METHODS: For 120 days, three subjects consumed 30 mg of lutein and 2.7 mg of zeaxanthin supplement per day. MPOD was measured with heterochromatic flicker photometry at 20', 30', 60' and 120' eccentricity three or four times per week. High-performance liquid chromatography was used to measure serum carotenoid concentrations in blood samples collected at baseline and at 30-day intervals. RESULTS: At the two most central loci, MPOD significantly increased in all three subjects with a mean change of approximately 0.09 log units at 20' eccentricity and 0.08 log units at 30' eccentricity. MPOD significantly increased in two subjects at 60' eccentricity, and in one subject at 120' eccentricity. The increases in MPOD appeared to be linear and continued after treatment was ended. In all three subjects, log sensitivity at the reference locus decreased linearly. Serum lutein and serum zeaxanthin increased from baseline, reaching peak concentrations after 30 days of supplementation. CONCLUSION: The changes in MPOD suggest that carotenoid deposition occurs linearly and may be biased towards the central retina. Further, carotenoid deposition may occur outside the central fovea in interventions with pharmacological doses of carotenoid, resulting in underestimations of psychophysical measures of MPOD.