On the age dependency of the macular pigment optical density

Macular pigment may protect against age related macular degeneration (AMD), because of its capability to absorb blue light and scavenge free radicals. Since age is the major risk factor in AMD, a fundamental question to be answered is the possible age dependence of the macular pigment optical density (MPOD) in normal healthy subjects. In this study we used five methods to study a possible age effect: heterochromatic flickerphotometry, two setups for fundus reflectance spectroscopy, a Scanning Laser Ophthalmoscope (SLO) for obtaining reflectance, and the same SLO for autofluorescence maps. MPOD was determined from the reflected light by a full spectral analysis. We also used a new, directional analysis of the reflected light to estimate MPOD. The latter avoids the disturbing influence of stray-light. Digital subtraction at two wavelengths of log reflectance and digital subtraction of log autofluorescence obtained with the SLO provided MPOD maps. Together, all methods of measuring and of analysis provided seven MPOD estimates per subject. A total of 53 subjects, aged 19-76 years, completed all five measurements (and thus seven analyses). An additional 81 subjects, aged 18-70 years, were measured with one setup for fundus reflectance spectroscopy (and thus only two analyses). We could not find any association with age with all the objective techniques. Only MPOD values obtained with heterochromatic flickerphotometry showed a small, but significant decrease with age. This decrease was caused by an increase in the parafoveal data, suggesting that the central MPOD is unchanged with age. The bivariate correlation coefficients between all methods were significant (all p<0.001).