Abstract
Purpose: :
To evaluate the influence of eccentric macular pigment (MP) on computations of relative optic density (OD) and total amount of MP using 2-wavelength fundus autofluorescence imaging.
Methods: :
Macular pigment optical density (MPOD) and the total complement of MP were measured in 38 healthy subjects using 2-wavelength fundus autofluorescence imaging (wavelengths 488nm and 514nm). Measurements were made relative to an eccentric reference location at 10.5 degrees eccentricity and were compared with measurements relative to 4.0, 6.0 and 8.0 degrees eccentricity.
Results: :
Peak MPOD relative to a reference location at 10.5 degrees ranged from 0.19 to 0.93. The mean MPOD dropped to 0.05 or less at between 3.1 and 8.0 degrees and to 0.02 or less between 5.6 and 9.4 degrees eccentricity. Eighteen subjects had MPOD values of 0.02 or more at 8 degrees eccentricity. Reducing the eccentricity of the reference location from 10.5 degrees to 4.0, 6.0 or 8.0 degrees reduced the relative peak MPOD by up to 27% (median 18%), 16% (median 10%) and 9% (median 4%) respectively; underestimation tended to be greater for subjects with low peak levels of MPOD. Comparison of the total complement of MP within the central 21.0 degrees with the amount in the central 8.0, 12.0 or 16.0 degrees led to underestimation of up to 68% (median 53%), 42% (median 27%) and 24% (median 8%) respectively.
Conclusions: :
Assessments of luteal pigment that employ a reference location at less than 10.5 degrees eccentricity may significantly underestimate the peak OD and total complement of MP.
Keywords: macular pigment • imaging/image analysis: clinical • carotenoids/carotenoid binding proteins