Monthly consistency of macular pigment optical density and serum concentrations of lutein and zeaxanthin

Purpose: This study was undertaken to assess serial month-to-month consistency of macular pigment (MP) optical density and serum concentrations of lutein (L) and zeaxanthin (Z). Four healthy subjects aged between 23 and 51 years volunteered to participate in this study. Methods: MP optical density (measured psychophysically using heterochromatic flicker photometry [HFP]), and serum concentrations of L and Z (quantified using high-performance liquid chromatography [HPLC]), were recorded every month for 24 consecutive months. Results: Mean MP optical density (±SD) was 0.361 (0.086) and 0.369 (0.074) for right and left eyes, respectively. There was no statistically significant seasonal variation in MP optical density for the group (two-way ANOVA: p > 0.05). Serum concentrations of L and Z demonstrated a statistically significant subject-season interaction effect (two-way ANOVA: p < 0.01). Serial serum concentrations of L and Z were positively correlated within all four subjects (r=0.370 to 0.786), and significantly so for three subjects (p < 0.05). There was no obvious relationship, synchronous or lagged, between serum concentrations of L (or Z) and MP optical density (r = -0.036 to 0.368). Conclusions: MP optical density was relatively stable for all subjects over the 24-month period. Fluctuations in serum concentrations of L and Z, in the absence of dietary modification or supplementation, are associated with stable MP optical density.