Better Understanding of Macular Pigment (MP) and Macular Pigment Optical Density (MPOD)
By Bridgitte Shen Lee, OD
In the last Blue Light Bulletin, I reviewed macular pigment (MP) which is composed of three carotenoids: Lutein (L), Zeaxanthin (Z), and Mesozeaxanthin (MZ).1,2 Function of MP and how it’s measured will be discussed here.
What is the Function of Macular Pigment?
The retina is the most metabolically active tissue in the human body, resulting in high oxygen requirement and high levels of oxidative stress. When oxidative stress exceeds the retina’s ability to cope, degradation products begin to accumulate as drusen, and cell apoptosis eventually occurs.3
A robust macular pigment filters out high energy visible blue light, protects macula from oxidative stress,4,5 and enhances vision.4
1. MP Decreases Oxidative Stress5
a. Quenches singlet oxygen and triplet state photosensitizers6,7,8
b. Inhibits peroxidation of membrane phospholipids9
c. Scavenges Reactive Oxygen Species (ROS)10
d. Reduces lipofuscin formation11,12
2. MP Enhances Vision
a. Filters Blue Light (380-500): reduces chromatic aberration, enhances visual acuity and Contrast Sensitivity (CS)13,14
b. Reduces Discomfort Glare: reduces photophobia13,14,15, improves Photo Stress Recovery (PSR) time16
Figure 1. Frozen section through the fovea of a rhesus monkey viewed in white light, blue light, and green light. The yellow macular pigment appears dark in the middle panel because it absorbs blue light, but it is not visible in green light.
What is MPOD?
Macular Pigment Optical Density is a measurement of the attenuation of blue light by macular pigment and is linearly related to the amount (concentration x path length x area) of lutein, zeaxanthin, and mesozeaxanthin in the macula.17
Several objective techniques have been used to measure MPOD indirectly and noninvasively. They are divided into two main methods.4
1. Psychophysical Method: HFP (heterochromatic flicker photometry)18
– HFP is based on the spectral absorption properties and retinal location of MP. It determines MPOD by presenting a light stimulus of two alternating wavelengths at the fovea and parafoveal area, one is short and maximally absorbed by MP, and another longer and not absorbed by MP19
2. Optical Methods: Autofluorescence Imaging (AFI),20 Fundus Reflectometry21
– The AFI method is based on the principle of autofluorescence of lipofuscin, which is located in the retinal pigment epithelium cells.20
– Fundus Reflectometry compares quantitative measurement of light reflected at the macula and light reflected from a peripheral area of the retina.21
Selection of proven macular pigment nutrition, and other relevance of MP such as a biomarker for Alzheimer’s and neuroprotection for glaucoma will be discussed in the next bulletin.
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2. Landrum JT, Bone RA. Lutein, zeaxanthin, and the macular pigment. Arch Biochem Biophys. 2001;385:28–40.
3. Roberts J, Dennison JE. The Photobiology of Lutein and Zeaxanthin in the Eye. J Ophthalmol. 2015;2015:687173. Epub 2015 Dec 20.
4. Lima VC, Rosen RB, Farah M. Macular Pigment in Retinal Health and Disease. Int J Retina Vitreous. 2016 Aug 15;2:19. eCollection 2016.
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6. Sujak A, Gabrielska J, Grudziński W, et al. Lutein and zeaxanthin as protectors of lipid membranes against oxidative damage: the structural aspects. Arch Biochem Biophys. 1999;371:301–7.
7. Junghans A, Sies H, Stahl W. Macular pigments lutein and zeaxanthin as blue light filters studied in liposomes. Arch Biochem Biophys. 2001;391:160–4.
8. Cantrell A, McGarvey DJ, Truscott TG, et al. Singlet oxygen quenching by dietary carotenoids in a model membrane environment. Arch Biochem Biophys. 2003;412:47–54.
9. Bhosale P, Bernstein PS. Synergistic effects of zeaxanthin and its binding protein in the prevention of lipid membrane oxidation. Biochim Biophys Acta. 2005;1740:116–21.
10. Li B, Ahmed F, Bernstein PS. Studies on the singlet oxygen scavenging mechanism of human macular pigment. Arch Biochem Biophys. 2010;504:56–60.
11. Lim BP, Nagao A, Terao J, et al. Antioxidant activity of xanthophylls on peroxyl radical-mediated phospholipid peroxidation. Biochim Biophys Acta. 1992;1126:178–84.
12. Nilsson SEG, Sundelin SP, Wihlmark U, Brunk UT. Aging of cultured retinal pigment epithelial cells: oxidative reactions, lipofuscin formation and blue light damage. Doc Ophthalmol. 2003;106:13–6.
13. Stringham JM, Fuld K, Wenzel AJ. Spatial properties of photophobia. Invest Ophthalmol Vis Sci. 2004;45:3838–48.
14. Wenzel AJ, Fuld K, Stringham JM, Curran Celentano J. Macular pigment optical density and photophobia light threshold. Vis Res. 2006;46:4615–22. doi:10.
15. Stringham JM, Hammond BR. The glare hypothesis of macular pigment function. Optom Vis Sci. 2007;84:859–64.
16. Stringham JM, Garcia PV, Smith PA, et al. Macular pigment and visual performance in glare: benefits for photostress recovery, disability glare, and visual discomfort. Invest Ophthalmol Vis Sci. 2011;52:7406–15.
17. Bernstein PS, Delori FC, Richer S, et al. The value of measurement of macular carotenoid pigment optical densities and distributions in age-related macular degeneration and other retinal disorders. Vis Res. 2010 Mar 31;50(7):716-28.
18. Wooten BR, Hammond BR, Land RI, Snodderly DM. A practical method for measuring macular pigment optical density. Invest Ophthalmol Vis Sci. 1999;40:2481–9.
19. Howells O, Eperjesi F, Bartlett H. Measuring macular pigment optical density in vivo: a review of techniques. Graefes Arch Clin Exp Ophthalmol. 2011;249:315–47.
20. Delori FC, Goger DG, Hammond BR, et al. Macular pigment density measured by autofluorescence spectrometry: comparison with reflectometry and heterochromatic flicker photometry. J Opt Soc Am A. 2001;18:1212–30.
21. Howells O, Eperjesi F, Bartlett H. Measuring macular pigment optical density in vivo: a review of techniques. Graefes Arch Clin Exp Ophthalmol. 2011;249:315–47.
Dr. Bridgitte Shen Lee earned an optometry degree from University of Houston College of Optometry in 1998. She is the CEO of Vision Optique and iTravelCE. She writes and lectures on the topics of Digital Eye Health, Dry Eye Disease, Anti-Aging Eye Care, Health Care Social Media, and Aesthetic Optometry.
Financial Disclosures: Johnson & Johnson Vision, Shire, Essilor, OCuSOFT, Guardion Health Sciences, Bausch & Lomb, Luxottica