title: Lutein and zeaxanthin measured separately in the living human retina with fundus reflectometry.
abstract: OBJECTIVE
  To separately measure the optical densities of lutein (L) and zeaxanthin (Z) in the human retina in vivo. L and Z are the basic constituents of the macular pigment (MP).
  
  
  METHODS
  Spectral fundus reflectance was measured in 23 subjects (group 1) at 0 degrees , 1 degrees , 2 degrees , 4 degrees , and 8 degrees eccentricity with a modified macular pigment reflectometer. A model generated the optical densities of L (LOD) and Z (ZOD), using their slightly different absorption spectra. Three other subjects (group 2) took 20 mg/d zeaxanthin for 6 months; they were measured approximately monthly for 18 months.
  
  
  RESULTS
  Mean LOD for group 1 at the central fovea was 0.200 +/- 0.061 (range, 0.085-0.305), mean ZOD was 0.494 +/- 0.169 (range, 0.169-0.806), resulting in a mean Z fraction [ZOD/(LOD + ZOD)] of 0.71. ZOD dropped faster toward the periphery than LOD, measuring 0.044 and 0.010 (Z fraction 0.18) at 8 degrees , respectively. Zeaxanthin supplementation in group 2 caused a significant increase in ZOD, and no or minor changes in LOD. ZOD further increased over a 10-month period after supplementation in all subjects.
  
  
  CONCLUSIONS
  LOD and ZOD had different spatial profiles that, apart from scaling factors, showed similarity to in vitro literature data. Supplementation with Z caused LOD to decrease and ZOD to increase. These results strongly suggest that the optical densities of L and Z can be assessed in vivo by fundus reflectometry, opening new ways of investigating the putative protective roles of L and Z in retinal disease.
authors.affiliation: Department of Ophthalmology, University Medical Center Utrecht, Utrecht, The Netherlands. jkraats@umcutrecht.nl
authors.forename: Jan
authors.initials: J
authors.lastname: van de Kraats
authors.forename: Martijn J
authors.initials: MJ
authors.lastname: Kanis
authors.forename: Stijn W
authors.initials: SW
authors.lastname: Genders
authors.forename: Dirk
authors.initials: D
authors.lastname: van Norren
mesh_terms: D000328:Adult; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D014975:Lutein / Q000008:administration & dosage / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D012160:Retina / Q000737:chemistry*; D012168:Retinal Pigments / Q000032:analysis*; D013053:Spectrophotometry; D024341:Xanthophylls / Q000008:administration & dosage / Q000032:analysis*; D055815:Young Adult; D065146:Zeaxanthins
chemical_list: D012168:Retinal Pigments; D024341:Xanthophylls; D065146:Zeaxanthins; D014975:Lutein