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Anthony G Robson, Jack D Moreland, Daniel Pauleikhoff, Erik J Van Kuijk; Macular Pigment Distribution Profiles: longitudinal stability over 13-17 years and eccentricity-dependent measurement errors.. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):1084.
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© ARVO (1962-2015); The Authors (2016-present)
To monitor the stability of macular pigment (MP) distribution profiles over periods of 13-17 years in 4 subjects and to assess eccentricity-dependent measurement errors from pooled data from 51 subjects.
MP distribution profiles were obtained using a motion photometer in 4 healthy subjects (A-D) monitored over periods in excess of 17 (N=2) and 13 (N=2) years. A square wave grating (460nm and 580nm) was moved at constant horizontal velocity (26 deg/sec and/or 37 deg/sec) within 2 circular fields (radius 0.45° and 1.1°) and 11 annular segments (maximum radius 7.5°). The radiance of the 580nm stimulus was adjusted to minimize the perceived motion. Optical density (OD) was computed at each location relative to the most eccentric area. The shape of the mean spatial distribution profiles for each of the 4 subjects (average of 53, 49, 14 and 12 profiles respectively) were characterised in detail. Data was obtained from an additional 47 heathy subjects and pooled MPOD standard deviations (SDs) for the 13 stimulus fields were compared with SDs computed from eccentricity-dependent fixation error statistics (Cherici et al., J Vis. 2012 Jun 22; 12 (6) pii: 31. doi: 10.1167/12.6.31).
Mean peak MPOD values obtained from 4 subjects tested regularly over 13-17 years were 0.87 (A), 0.76 (B), 0.45 (C) and 0.16 (D). Linear regression through serial data points (circular field; radius 1.1°) gave gradients of 0.0063 (A), 0.0008 (B), 0.0006 (C) and -0.0013 (D) per year. Largest gradients at 4 eccentricities at or between 0.82 and 2.31 degrees were 0.0037 (A), -0.0051 (B), 0.0036 (C) and -0.0039 (D) per year. Averaged data from 51 subjects revealed that measurement errors were greatest for the central and the most eccentric stimulus fields and were least between 2.3 and 4.3 degrees eccentricity. Pooled SDs for MPOD (51 subjects) correlated with SDs computed from fixation error statistics for the large foveal field and for eccentricities of between 0.82 and 2.8 degrees (r2=0.92) but correlation was poor for the small foveal field and for more eccentric stimuli.
Widely different MP distribution profiles in healthy subjects demonstrate a high degree of stability over periods of 13-17 years. Variable fixation contributes significantly to MP measurement errors over parafoveal locations.
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