Influence of macular pigment and melanin on incident early AMD in a white population.

BACKGROUND

The protective effect of macular pigment (MP) and melanin against age-related macular degeneration (AMD) is still controversial from cross-sectional studies. In an attempt to clarify this issue, we performed a population-based longitudinal study.

METHODS

MP optical density (MPOD) and melanin optical density (MOD) data were collected during the second follow-up phase of the Rotterdam Study in 1999 in a random subset of 435 participants. Data from 419 participants (98% white) was available for analysis. AMD diagnosis was based on standardized fundus photographs according to the International Classification System, and AMD cases were subdivided into five mutually exclusive stages. In the three follow-up phases, incident AMD (iAMD), defined as absence of any AMD at baseline and the presence of stage 2 or higher at follow-up, was determined. We used Cox regression analysis to study the effect of an assumedly stable MPOD and MOD on early iAMD.

RESULTS

During a mean follow-up of 9.82 years, 13 male and 17 female participants developed early iAMD and two male participants late iAMD. Because only two participants developed late iAMD, we had to restrict our analyses to early iAMD. Cox regression analysis adjusted for age and gender showed no significant effect of MPOD [hazard ratio (HR) 0.37; 95% confidence interval (CI) 0.04, 3.57] and MOD (HR 0.56; 95% CI 0.09, 3.60) on early iAMD. Additional adjustment for smoking did not change these associations.

CONCLUSIONS

This unique but quantitatively limited material leads to the conclusion that no major protective effect of MPOD or MOD was seen on early iAMD.