title: Light exposure and macular pigment optical density.
abstract: OBJECTIVE
  Biochemical research has demonstrated that lutein and zeaxanthin, the two macular carotenoids, are bleachable pigments. Further, evidence suggests that exposure to UV light can degrade plasma carotenoid levels in vivo. The present study investigated the effects of exposure to normal levels of light on the levels of lutein and zeaxanthin in the retina.
  
  
  METHODS
  The optical density of macular pigment (MPOD) was measured in two male subjects under four different light-adaptation conditions for 20 days. Heterochromatic flicker photometry was used to measure MPOD at 0.5 degrees eccentricity.
  
  
  RESULTS
  The four conditions of light adaptation did not significantly affect MPOD. As in previous studies, however, a significant day-to-day difference was observed for both subjects.
  
  
  CONCLUSIONS
  The results suggest that lutein and zeaxanthin levels in the eye are unaffected by light and oxidation throughout the day. This justifies current research methods in which MPOD measures are made regardless of the time of day. However, significant between-day variance indicates that multiple MPOD measures may be necessary to evaluate lutein and zeaxanthin levels in the retina accurately.
authors.affiliation: Department of Psychology, University of New Hampshire, 10 Library Way, Durham, NH 03824-3567, USA.
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Wenzel
authors.forename: Kenneth
authors.initials: K
authors.lastname: Fuld
authors.forename: James M
authors.initials: JM
authors.lastname: Stringham
mesh_terms: D000221:Adaptation, Ocular; D000328:Adult; D006801:Humans; D008027:Light; D014975:Lutein / Q000378:metabolism; D008297:Male; D012160:Retina / Q000378:metabolism / Q000528:radiation effects*; D012168:Retinal Pigments / Q000378:metabolism*; D024341:Xanthophylls; D065146:Zeaxanthins; D019207:beta Carotene / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D012168:Retinal Pigments; D024341:Xanthophylls; D065146:Zeaxanthins; D019207:beta Carotene; D014975:Lutein