Abstract
Purpose::
To investigate the spatial distribution of the macular pigment (MP) and its relation with age and gender.
Methods::
The study population was 78 subjects with normal retinal status (49 women, 29 men) 50 to 82 years old. MP was measured with a modified SLO using the autofluorescence (AF) method (488/514 nm). Analysis yielded the MP optical density profile, the peak density MPDp (mean within a 0.2°-diameter circle centered on the fovea), the density MPDc (mean in a 1°-circle), and the full width at half maximum (FWHM). The shape of the profiles were objectively classified into 3 types by differential analysis: (1) profiles with a central "peak" and a monotonic decrease with increasing eccentricity, (2) profiles with a central minimum or "pit" and an annular maximum at eccentricities >0.1°, and (3) profiles with a central peak and a "ring" of higher density or a marked inflection on the slope of the profile.
Results::
Mean MPDc was 0.46±0.15 D.U. (range: 0.15 to 0.90 D.U.) and MPDp was 0.68±0.21 D.U. (range: 0.2 to 1.2 D.U.), with no significant gender difference. Incidence of profile shape was 60% for "peak", 26% for "ring", and 14% for central "pit". Significant gender differences were found in the incidence of the profile shapes (2x3 chi2; p=0.01). "Peak" types were found in 49% of women and 79% of men; "ring" types were found in 31% of women and 17% of men, and central "pits" were found in 20% of women and 4% of men. Women were more likely to show profiles that were not of the "peak" type (p=0.008). The width FWHM was 2.0±0.7° for those subjects that did not exhibit a central "pit"; there was a tendency for women to have a wider distribution (p=0.13).
Conclusions::
The spatial distribution of MP can substantially deviate from an exponential-like distribution. These deviations occur more frequently in women than in men, consistent with some (Elsner 1998; Delori 2006) but not all (Berendschot 2005) previous studies. These differences may be related to anatomical differences in the shape of the foveal depression, or to other factors. The relevance of these findings in the prognosis of ARM needs further studies.
Keywords: macular pigment • macula/fovea • age-related macular degeneration