Macular pigment profile characteristics and stability over periods of up to 25 years

Abstract

This study compares the foveal and total retinal macular pigment (MP) amount in healthy subjects and examines the stability of MP spatial distribution profiles, measured almost annually for periods of up to 25 years.Measurements of MP spatial distribution profiles were made by 51 subjects using the psychophysical technique of minimum motion photometry, utilizing a moving bichromatic grating (test 460 nm, comparison 580 nm). Two foveal fields (0.9° and 2.2° diameter) and 11 annular segments (eccentricities from 0.8° to 7.5°) were used. The total amount of MP within the central 15 degrees was estimated by numerical integration and compared with foveal values. Four subjects with widely different MP profiles underwent almost annual testing for periods of 19–25 years. Eleven of the same subjects and 19 others underwent 2‐wavelength autofluorescence (AF) assessment of MP using a scanning laser ophthalmoscope (incident radiation 488 nm and 514 nm), allowing quantification of the peak relative optical density, distribution and total complement of MP over the central 21 degrees.Detailed examinations revealed widely different MP distribution profiles using motion photometry and/or 2‐wavelength fundus autofluorescence. There was a lack of correlation between peak MP optical density at the fovea and assessments of the total complement of MP within the central 15 or 21 degrees. Serial psychophysical assessments over periods of 19–25 years in 4 cases demonstrated a high degree of stability at all macular locations including the fovea; plots of peak MP optical density against time showed minimal positive and negative gradients (<0.0003).The total amount of macular pigment cannot be accurately estimated from foveal or central values. Widely different MP distribution profiles in healthy subjects demonstrate a high degree of long‐term stability, relevant to investigations that aim to monitor MP or fundus autofluorescence in disease or in studies that aim to modify MP through dietary supplementation.