L Patryas, J Cher, IYF Leung, K Neelam, M Makridaki, D Carden, TTJM Berendschot, RLP
van der Veen & IJ Murray
In: Macular Carotenoid Conference; Cambridge. 2013.
Purpose: Measuring macular pigment optical density (MPOD) with different methods appear
to produce differing results in the same individuals, especially when dissimilar principles
are employed. Ascertaining to what degree these methods correlate will enable the
scientific community to interpret past and future research studies in this field.
Here we describe two series of experiments which compare recent techniques used to
measure MPOD. Methods: First, we used a macular pigment reflectometer1 (MPR) with
capture angle 1, modified to measure at eccentricities of 0, 1, 2, 4, 6 and
8. These data were compared with those obtained from the Macular Pigment Screener2
(MPS) modified to assess MPOD at 0.5, 1, 2, 4, 5, 6 and 7. Nineteen healthy
individuals (mean age 26 8 years) were tested. In a second experiment, we compared
the right eyes of twenty-five healthy individuals (mean age 23 3 years) using MPS
and a Macular Densitometer2 (MD).Results: There was a strong correlation between the
MPR and the MPR techniques (r = 0.72, p = 0.001) with the absolute estimates obtained
by MPS being lower than by MPR. These differences could be explained by i) non-zero
values at 8 eccentricity and ii) assuming the subjects used a point 0.4 from the
centre of the stimulus to set flicker thresholds. The correlation between the MPS
and MD was high (r = 0.82, p < 0.0001), with the MPS again producing lower absolute
values. Repeatability was assessed with 10 individuals. Coefficients of repeatability
for MPD and MPS were 0.21 and 0.06, respectively. Conclusions: The MPS, the MPR and
the MD provide broadly similar results. It is inevitable that different absolute values
are obtained, The important factor is the predictability from one method to another.
It is essential that practitioners obtain normative data for any particular instrument
as it is well known that many factors influence the assessment of MPOD. The MPS has
the advantage of the centre-only facility, designed for clinical practice. This enables
rapid determination of MPOD and is ideal when differences between consecutive measurements
are required when monitoring the results of supplementing with retinal carotenoidsDisclosures:
The MPS is protected by a patent owned by Ian Murray and David Carden.References 1.
van de Kraats J, Berendschot TT, Valen S, & van Norren D (2006): Fast assessment of
the central macular pigment density with natural pupil using the macular pigment reflectometer.
J Biomed Opt 11(6):064031.2. van der Veen RL, Berendschot TT, Makridaki M, Hendrikse
F, Carden D & Murray IJ (2009): Correspondence between retinal reflectometry and a
flicker-based technique in the measurement of macular pigment spatial profiles. J
Biomed Opt.14(6):064046. 3. Wooten BR, Hammond BR, Land RI & Snodderly DM (1999):
A practical method for measuring macular pigment optical density. Invest Ophthalmol
Vis Sci 40:2481–2489.