Ocular nutrition topics come up during primary eye care exams more often now as our population ages. By 2030, at least 18% of the U.S. population will be age 65 or older.1 By 2050, the estimated number of people with AMD (Age Related Macular Degeneration) is expected to more than double from 2.07 million to 5.44 million.2 One of the proven strategies to combat macular degeneration and provide longterm ocular health protection is through nutritional supplementation.3
In the past decade, the protective role of the Macular Pigment (MP) in filtering blue light and reducing oxidative damage has been extensively investigated. In the next few columns, I will review the research in macular carotenoid (MC) supplementation to improve MP Optical Density (MPOD),7,8 clinical measurement of MPOD and selection of carotenoid supplement,7,8 and the role of optometrists in incorporating proven ocular nutrition to benefit both AMD patients3 and high screen-time digital device users.15
What is Macular Pigment (MP)?
The central portion of the retina or macula is responsible for optimal spatial vision.4 Macular pigment (MP) is the term used to describe the yellow pigment concentrated at the macula. It is composed of the three isomeric xanthophyll carotenoids: meso-zeaxanthin (MZ), lutein (L), and zeaxanthin (Z).5,6 Macular pigment concentration peaks at the foveola. L is the dominant carotenoid in the peripheral macula, Z in the mid-peripheral macula, and MZ at the epicenter of the macula.5 -10
Figure 1. Original source: Britton G. Structure and properties of carotenoids in relation to function. FASEB J. 1995;9:1551–8. 7,11
What are Macular Carotenoids (MC)?
Carotenoids are organic pigments that are produced by plants and algae, as well as several bacteria and fungi. There are over 600 known carotenoids; they are split into two classes: xanthophylls (which contain oxygen and can cross the blood-ocular or blood-brain barrier12,13,14) and carotenes (which include beta-carotene and lycopene, are purely hydrocarbons and contain no oxygen, and cannot cross the blood-brain or ocular barrier until metabolized13,14). Lutein, zeaxanthin, and meso-zeaxanthin are the only three xanthophyll macular carotenoids11,12 and together they form powerful antioxidant and blue light filtering macular pigment (MP).11,16
MP’s vital role in visual and brain function and the optometrist’s role in ocular health protection will be discussed in future columns.
1. Pew Research Center. Baby Boomers Retire. Available at: http://www.pewresearch.org/daily-number/baby-boomers-retire (Last accessed August 20, 2017).
2. National Eye Institute. Projections for AMD (2010-2030-2050). Available at: https://nei.nih.gov/eyedata/amd (Last accessed August 20, 2017).
3. Karpecki P, Sherman J, Beatty S, Renzi-Hammond LM. Transforming Eye Health through Proven Ocular Nutrition Strategies. Review of Optometry. 2016 Feb; Supplement
4. Hirsch J, Curcio CA. The spatial resolution capacity of human foveal retina. Vis Res. 1989;29:1095–101.
5. Bone RA, Landrum JT, Friedes LM, et al. Distribution of lutein and zeaxanthin stereoisomers in the human retina. Exp Eye Res. 1997;64:211–8.
6. Landrum JT, Bone RA. Lutein, zeaxanthin, and the macular pigment. Arch Biochem Biophys. 2001;385:28–40.
7. Nolan JM, Power R, Stringham J, Dennison J, et al. Enrichment of Macular Pigment Enhances Contrast Sensitivity in Subjects Free of Retinal Disease: Central Retinal Enrichment Supplementation Trials (CREST) - Report 1. Invest. Ophthalmol. Vis. Sci. 2016, 57, 3429–3439.
8. Lima VC, Rosen RB, Farah M. Macular Pigment in Retinal Health and Disease. Int J Retina Vitreous. 2016 Aug 15;2:19. eCollection 2016.
9. Snodderly DM, Auran JD, Delori FC. The macular pigment. II. Spatial distribution in primate retinas. Invest Ophthalmol Vis Sci. 1984;25:674–85.
10. Trieschmann M, van Kuijk FJ, Alexander R, et al. Macular pigment in the human retina: histological evaluation of localization and distribution. Eye (Lond). 2008;22:132–7.
11. Britton G. Structure and properties of carotenoids in relation to function. FASEB J. 1995;9:1551–8.
12. Stahl W. Macular carotenoids: lutein and zeaxanthin. Dev Ophthalmol. 2005;38:70–88.
13. Roberts JE, Dennison J. The photobiology of lutein and zeaxanthin in the eye. J Ophthalmol. 2015;2015:1–8.
14. Shete V, Quadro L. Mammalian metabolism of β-carotene: gaps in knowledge. Nutrients. 2013;5:4849–68.
15. Stringham JM, Stringham NT, O’Brien KJ. Macular Carotenoid Supplementation Improves Visual Performance, Sleep Quality, and Adverse Physical Symptoms in Those with High Screen Time Exposure. Foods. 2017, 6, 47.
16. Nolan JM, Meagher K, Kashani S, Beatty S. What is meso-zeaxanthin, and where does it come from? Eye (Lond). 2013;27:899–905.
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