title: Macular pigment measurement by heterochromatic flicker photometry in older subjects: the carotenoids and age-related eye disease study.
abstract: OBJECTIVE
  To develop a standardized protocol for measuring macular pigment optical density (MPOD) of experimentally naïve subjects by heterochromatic flicker photometry (HFP).
  
  
  METHODS
  MPOD in eyes of 54 women, age 50 and 79 years (mean, 66), was studied. The spatial profile of MPOD was measured in the right eye, and two spatial points were also measured in the left eye. Forty-eight of these inexperienced subjects completed the protocol on two separate visits. For a subset of the group, the MPOD at two different wavelengths was measured.
  
  
  RESULTS
  The test-retest correlation at 0.5 degrees eccentricity in the right eye was 0.9. On the second visit, more than 90% of the subjects were able to perform the HFP test with results that were consistent with the absorption spectrum of macular pigment. On the first visit, data from the inexperienced subjects deviated more from the expected relationships between the two wavelengths, presumably because they had less skill in performing the task. However, subjects with high or low macular pigment density were distinguished clearly.
  
  
  CONCLUSIONS
  Reliable and meaningful measurements of macular pigment density in older subjects can be made using HFP, with a standardized protocol in the limited time available in large epidemiologic studies. This protocol will be made freely available to other researchers on request.
authors.affiliation: Schepens Eye Research Institute, Boston, Massachusetts, USA. msnodderly@mcg.edu
authors.forename: D Max
authors.initials: DM
authors.lastname: Snodderly
authors.forename: Julie A
authors.initials: JA
authors.lastname: Mares
authors.forename: Billy R
authors.initials: BR
authors.lastname: Wooten
authors.forename: Lisa
authors.initials: L
authors.lastname: Oxton
authors.forename: Michael
authors.initials: M
authors.lastname: Gruber
authors.forename: Tara
authors.initials: T
authors.lastname: Ficek
mesh_terms: D000368:Aged; D002338:Carotenoids / Q000008:administration & dosage*; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D006801:Humans; D008266:Macula Lutea / Q000737:chemistry*; D008268:Macular Degeneration / Q000517:prevention & control*; D008875:Middle Aged; D010783:Photometry / Q000379:methods; D015203:Reproducibility of Results; D012168:Retinal Pigments / Q000032:analysis*
chemical_list: D012168:Retinal Pigments; D002338:Carotenoids