Lutein and Zeaxanthin measured separately in the living human retina with fundus reflectometry
Jan van de Kraats 1*,
Martijn J Kanis 2,
Stijn W Genders 2,
and
Dirk van Norren 2
1 Ophthalmology, UMC Utrecht, AZU E03.136, Utrecht, 3508 GA, Netherlands
2 Ophthalmology, UMC Utrecht, Utrecht, Netherlands
* To whom correspondence should be addressed. E-mail: jkraats{at}umcutrecht.nl.
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Abstract |
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PURPOSE. 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, 1, 2, 4, and 8 deg eccentricity with a modified Macular Pigment Reflectometer. A model generated the optical densities of L (LOD) and Z (ZOD), utilizing their slightly different absorption spectra. Three other subjects (group 2) took 20 mg/day zeaxanthin for 6 months; they were measured about 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 towards the periphery than LOD, measuring 0.044 and 0.010 (Z fraction 0.18) at 8 deg 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.
Key Words:
Macular pigment, zeaxanthin, lutein, reflectometer, retinal eccentricity, supplementation trial
