Abstract
Purpose: :
To identify the correlates of macular pigment optical density (MPOD) in Mid–South elderly subjects participating in ARMA, an investigation ancillary to the Health ABC Study.
Methods: :
MPOD could be estimated foveally with a heterochromatic flicker photometry–based method (0.5–deg eccentricity) in 183 (19% Black), 78.9 ± 3.2 yo healthy subjects (M=83; F=94), for a total of 341 estimates. Ocular and systemic variables were evaluated as possible correlates in univariate and multivariate analyses (α=0.01). Positive or negative correlations are identified as (+) or (–), respectively.
Results: :
MPOD was significantly correlated with: (–) Black race, percent of anterior cortical cataract, grade of nuclear opacity, ever–smoking, vasodilator use (VDU, a proxy for cardiovascular disease), retinol (ROH, borderline significant), and γ–tocopherol (TOC); (+) contrast sensitivity (CS), lutein supplement use (LSU), serum lutein and zeaxanthin (L&Z), α–carotene, lycopene, and α–TOC. In a multivariate analysis, race, LSU, serum L&Z, lycopene, ROH, γ–TOC remained significant independent correlates and explained 18.7% of MPOD variability (p <0.0001; n=335). In analyses stratified by gender, serum L&Z was a significant (+) MPOD correlate in females but not in males (both in uni– and multivariate analyses). Stratifying by race, in Blacks neither LSU nor any ocular variable correlated with MPOD, and a (+) correlation was seen with BMI and other body fat measures; in multivariate analyses, only gender, serum L&Z, vit. C use, BMI and abdominal circumference were correlated with MPOD and explained 47.3% of its variability (p <0.0001; n=58). Unlike Blacks, Whites showed a non–significant (–) correlation with BMI and body fat. At the multivariate level, a model inclusive of CS, LSU, serum L&Z, ROH and γ–TOC explained 20% of MPOD variability in Whites (p <0.0001; n=268), and one inclusive also of vit. C use, VDU and, for phakic eyes, of nuclear and cortical lens opacities explained 35.2% of it (p <0.0001; n=161).
Conclusions: :
Several biologically plausible systemic and ocular variables correlated significantly with MPOD in healthy elderly subjects, explaining a substantial proportion of MPOD variability. Race and gender affected profoundly these relationships.
Keywords: macular pigment • aging • clinical (human) or epidemiologic studies: biostatistics/epidemiology methodology