You’ve probably heard that lutein and zeaxanthin are good for the eyes. These two major carotenoids found in the macula and retina are sometimes called xanthophylls or macular pigment. They function as antioxidants and also help protect tissues from phototoxic damage by filtering out some of the blue light.
The eye, and particularly the macula and retina, are almost constantly subjected to free radical generation and oxidative damage. Just as exposure to too much sunlight can damage the skin, so too can light damage the eyes. It is, thus, critical that you maintain your basic nutrients and especially antioxidants in the eye.
A study of macaque monkeys (with eyes similar to humans) showed that there was more zeaxanthin than lutein in the central fovea where vision is most clear. But, the concentration of zeaxanthin is reduced the further you get from the fovea and lutein dominates.
The macula has a yellow tint due to the presence of lutein, zeaxanthin and another xanthophyll called meso-zeaxanthin. It’s these pigments that help filter out or absorb some of the more damaging blue light to help protect the eye.
Age-related macular degeneration affects nearly 2 million Americans. More than 7 million Americans are at substantial risk for developing age-related macular degeneration. Some estimate that nearly 3 million people will be affected by 2020. Macular degeneration is the leading cause of central visual impairment that affects reading, driving, recognizing faces and performing close-up work among people aged 65 and above.
What Causes Age-Related Macular Degeneration?
The exact way age related macular degeneration develops is unknown. But, oxidative stress of the retina is thought to be a major contributor. The high concentration of oxygen and exposure to intense light seem to make the retina susceptible to oxidative damage.
Smoking is a well known way to deplete antioxidants. Smoking also increases blood viscosity and constricts blood vessels thus reducing the blood flow to the eyes. Every cigarette you smoke does damage to your eyes.
As the name (“age-related” macular degeneration) implies, age also plays its part. The aging of the retinal pigment epithelial layer and Bruch’s membrane (the layer below the epithelial layer) can allow the accumulation of debris and drusen. And, any existing abnormality typically worsens with age causing further damage and dysfunction of the retinal pigment epithelial layer.
Once the retinal pigment epithelial cells are damaged they secrete several growth factors including vascular endothelial growth factor (VEGF) which encourages the growth of new blood vessels (choroidal neovascularization) that cause problems in the “wet” form of age-related macular degeneration.