Abstract
Purpose: :
To compare measurements of macular pigment optical density (MPOD) and distribution using motion photometry and 2-wavelength autofluorescence (AF) and to determine the relationship between the foveal and total retinal MPOD complements using both techniques.
Methods: :
Measurements of MPOD retinal profiles were made by 47 subjects using minimum motion photometry (test 460nm, comparison 580nm). Two foveal fields (0.9º and 2.2º diameter) and 11 annular segments (eccentricities from 0.8º to 7.5º) were used. Eleven of the same subjects underwent 2-wavelength AF assessment of MPOD using a scanning laser ophthalmoscope (incident radiation 488nm and 514nm), allowing quantification of MPOD over complete annuli of equal width and eccentricity to the areas tested psychophysically.
Results: :
Minimum motion estimates of MPOD correlated with 2-wavelength AF measurements (r2=0.9, p<0.005, slope = 0.99). A plot of the difference between motion and 2-wavelength AF estimates of MPOD against the average revealed minimal differences (bias = 0.02, standard deviation = 0.06) with almost all data falling within the 95% limits of agreement. Macular pigment profiles were used to compute the total MPOD complement by numerical integration. The total amount of computed MP depended greatly on the parafoveal distribution and shape of the profile irrespective of the measurement technique.
Conclusions: :
Psychophysical estimates of macular pigment optical density and distribution show close correspondence with 2-wavelength autofluorescence measurements. The computed total amount of macular pigment cannot be accurately estimated from foveal values.
Keywords: macular pigment • carotenoids/carotenoid binding proteins • color vision