July 8, 2011By Steve Myers
- Lutein and Zeaxanthin, the main macular pigments, limit macular degeneration and are linked to reduced incidence of cataract.
- Anti-inflammatory omega-3s DHA and EPA positively impact glaucoma and dry eye, improving tear production and maintaining corneal epithelial integrity.
- Flavonoid-rich herbal products—black currants, bilberry, pine bark extract and curcumin, for example—address inflammatory and oxidative factors in eye health.
Blindness is scarier than heart disease, according to respondents of the “Eye on Eyesight" survey, which was conducted by Surge Research for the nonprofit Choice Magazine Listening. While nearly twice the number of respondents aged 50 to 64 years said they feared losing their eyesight more than than they feared heart disease, 79 percent of adults said losing their eyesight is the third biggest fear after their own death and the death of a loved one.
Forgoing the connection between death and heart disease, the importance of eyesight to quality of life is apparent. Sight endows us with not just aesthetic rewards, but it also provides us valuable information and tools for our interactions with the world and other beings.
The National Federation of the Blind (NFB) estimated 1.75 million people in the United States are legally blind—central visual acuity of 20/200 or less in the better eye with the best possible correction, or a visual field of 20 degrees or less. However, NFB further noted as many as 10 million Americans are blind or visually impaired—including some 5.5 million seniors—with 75,000 additional people joining the ranks of blind or visually impaired each year. Given just 1 percent of Americans are born blind, the majority of blindness occurs later in life due to deterioration caused by diseases such as age-related macular degeneration (AMD), glaucoma and diabetes.
To see is to process light. The cornea layer of the eye focuses light through the pupil, lens and vitreous fluid to the retina. An ultra-sensitive layer of photoreceptor cells, the retina absorbs the incoming light and converts it to nerve signals. The optic nerve attached at the back of the eye carries these signals to the brain for further processing and use of the information.
Among the neuronal photoreceptor cells in the retina are the rods and cones. Found more on the periphery of the retina, the rods number in the hundreds of millions and are adept at black and white vision in dimmer environments. There are far fewer cones, about 7 million, which dominate the central retina and handle colors and brighter environments. High-resolution central vision, however, is handled by the macula, a yellow-pigmented area near the center of the retina. Its yellow color comes from its content of the xanthophyll carotenoids lutein and zeaxanthin, and is responsible for the macula’s ability to filter blue and ultraviolet (UV) light.
Lutein and zeaxanthin are derived from the diet, found in abundance in dark, leafy greens such as spinach, kale and collards, and moderately plentiful in vegetables such as bell peppers, corn and broccoli. There is mounting evidence that increased consumption of lutein and zeaxanthin improves the macular pigment optical density (MPOD), indicating an important role in preserving vision and supporting retinal function.1 DSM researchers found the xanthophylls increased MPOD in different areas of the macula: lutein appears to be predominant in the fovea, while zeaxanthin covers a wider retinal area.2
Zeaxanthin has been shown to improve human color vision, visual acuity and vision in low-light conditions in healthy adults.3 Subjects took regular supplements of zeaxanthin, lutein, a combination of the two or placebo. Those who took lutein and zeaxanthin showed significant improvements in visual acuity and color vision.
These yellow carotenoids take a multifaceted approach to eye health, absorbing potentially harmful bands of spectral light, protecting against oxidative stress and damage, and helping to stymie inflammation.
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