title: Apparent motion photometry: evaluation and reliability of a novel method for the measurement of macular pigment.
abstract: OBJECTIVE
  Macular pigment is thought to protect the macula against exposure to light and oxidative stress, both of which may play a role in the development of age-related macular degeneration. The aim was to clinically evaluate a novel cathode-ray-tube-based method for measurement of macular pigment optical density (MPOD) known as apparent motion photometry (AMP).
  
  
  METHODS
  The authors took repeat readings of MPOD centrally (0°) and at 3° eccentricity for 76 healthy subjects (mean (±SD) 26.5±13.2 years, range 18-74 years).
  
  
  RESULTS
  The overall mean MPOD for the cohort was 0.50±0.24 at 0°, and 0.28±0.20 at 3° eccentricity; these values were significantly different (t=-8.905, p<0.001). The coefficients of repeatability were 0.60 and 0.48 for the 0 and 3° measurements respectively.
  
  
  CONCLUSIONS
  The data suggest that when the same operator is taking repeated 0° AMP MPOD readings over time, only changes of more than 0.60 units can be classed as clinically significant. In other words, AMP is not suitable for monitoring changes in MPOD over time, as increases of this magnitude would not be expected, even in response to dietary modification or nutritional supplementation.
authors.affiliation: Ophthalmic Research Group, School of Life and Health Sciences, Aston University, Birmingham B4 7ET, UK. h.e.bartlett@aston.ac.uk
authors.forename: Hannah
authors.initials: H
authors.lastname: Bartlett
authors.forename: Frank
authors.initials: F
authors.lastname: Eperjesi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003720:Densitometry / Q000379:methods*; D005260:Female; D006801:Humans; D008266:Macula Lutea / Q000033:anatomy & histology*; D008297:Male; D008875:Middle Aged; D009068:Movement; D015203:Reproducibility of Results; D012168:Retinal Pigments; D055815:Young Adult
chemical_list: D012168:Retinal Pigments