What do we know about the macular pigment in AMD: the past, the present, and the future

Abstract

Carotenoids are lipophilic isoprenoid pigments with a common CH core chemical structure that are naturally synthesized by many plants, algae, bacteria, and fungi. Humans and animals cannot synthesize carotenoids de novo and must obtain them solely through dietary sources. Among the more than 750 carotenoids in nature, only lutein, zeaxanthin, meso-zeaxanthin, and their oxidative metabolites selectively accumulate in the foveal region of the retina where they are collectively referred to as the macular pigment (MP) of the macula lutea. MP serves an ocular protective role through its ability to filter phototoxic blue light radiation and also via its antioxidant activity. These properties have led to the hypothesis that carotenoids may protect against the development of age-related macular degeneration (AMD), the most common cause of blindness in the aged population >60 years old. Epidemiological studies have supported this by showing that patients with lower concentrations of serum carotenoids and macular pigment optical density (MPOD) measurements are at a higher risk of developing AMD. Conversely, nutritional supplementation and diets rich in lutein and zeaxanthin readily impact MP concentrations and reduce the risk of progression to advanced AMD, and the AREDS2 supplement formulation containing 10 mg of lutein and 2 mg of zeaxanthin is the standard-of-care recommendation for individuals at risk for visual loss from advanced AMD. This article reviews the rich history of research on the MP dating back to the 1700s and outlines their potential for further therapeutic improvements for AMD in the future.

Subretinal Drusenoid Deposits in the Elderly in a Population-Based Study (the Montrachet Study)

“…Carotenoid macular bioavailability is influenced by various factors, but studies showed that carotenoid incorporation in the macula is mainly based on lipoprotein transport mechanisms such as IRBP, requires a minimal diet intake of fat and that polyunsaturated fatty acid-rich diet improves absorption of carotenoids. [44][45][46] suggested a link between macular pigment delivery system through Müller glial cells and the formation of drusen. We may hypothesize that, despite the established benefit of L/Z supplementation to the foveal vision, there may be a price to be paid for the delivery of L/Z to the fovea, namely a higher lipid uptake in the RPE and the retina, which then must be discarded as drusen or SDD.…”

Lutein and Zeaxanthin Isomers Reduce Photoreceptor Degeneration in the Pde6brd10 Mouse Model of Retinitis Pigmentosa

“…The antioxidants used for the treatment in this study are L-Z, which can neutralize reactive oxygen species to counter oxidative damage in retinal cells in many eye disorders [23, 53–56]. In addition, our previous study showed that L-Z reduce ERS in light-induced retinopathy [34].…”

Raman spectroscopy analysis of molecular configuration forms of the macular xanthophylls

“…An anatomical structure in the retina of the human eye particularly rich in carotenoids is referred to as the macula lutea or the yellow spot, due to its intense colouration . Three polar carotenoids, called xanthophylls, have been identified in the macular pigment pool, namely, lutein (Lut), zeaxanthin (Zea) and meso ‐zeaxanthin ( m ‐Zea) (see Figure ) . Resonance Raman spectroscopy of macular xanthophylls can be effectively applied to examine their properties in the natural system or even for imaging the retina, owing to the relatively strong Raman scattering signal of polyene dyes .…”