Macular pigment (MP) such as lutein, zeaxanthin and meso-zeaxanthin are highly concentrated in the fovea. They protect the retina from damage of ambient blue light via antioxidant properties. In older eyes with normal healthy retina, macular pigment optical density (MPOD) is associated with better foveal light sensitivity. Slowed rod-mediated dark adaptation (RMDO) in ageing and macular degeneration (AMD) seems to be attributed to impaired transport between the choroid and the retinal pigment epithelium (RPE)-Bruch’s-subretinal space. This study sought to find an association between MPOD and RMDO in older population with normal maculas. Three hundred and six eyes from 306 participants were included, with mean age of 68.2 years. The study did not reveal any relationship between MPOD and RMDA (which averaged at 11.09 minutes in this group). This is explained by the relatively low levels of MP in rod outer segments compared to foveal centre, Henle fibre layer and outer plexiform layer. In fact, recent evidence show that the principal MP reservoir in the human retina are the Muller glia. Variations in MPOD topography are attributed to structural differences in foveal shape, in turn attributable to Muller cells that span the retina as a structural framework for all cells. Future studies are necessary to address the impact of macular pigment on vision.

Rod-mediated dark adaptation and macular pigment optical density in older adults with normal maculas.
Zarubina AV, Huisingh CE, Clark ME, et al.
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Kurt Spiteri Cornish

Sheffield Teaching Hospitals NHS Trust, London, UK.

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