Oct 14 2008
European research has revealed that blue light exposure from the sun combined with low plasma levels of antioxidants may contribute to certain forms of the eye disease age-related macular degeneration (AMD).
A study by scientists at the London School of Hygiene & Tropical Medicine has found that though wavelengths in the UV radiation range are largely absorbed by the cornea and lens, the retina is exposed to visible light, including blue light which may damage the retina and contribute to the development of AMD.
AMD occurs when the area of the retina (macula) responsible for sharp vision deteriorates and the researchers say the retina is vulnerable to the damaging effects of light.
Dr. Astrid E. Fletcher and colleagues say antioxidant enzymes - including vitamins C and E, the carotenoids (lutein and zeaxanthin) and zinc, may protect against the harmful effects of blue light on the retina.
For their study they measured the levels of these nutrients in the blood of 4,753 adults with an average age 73, who were part of the European Eye Study - the participants also were questioned about their lifetime sunlight exposure and had photographs taken of their retinas to detect AMD.
Of the 4,400 participants who were able to provide complete information, 2,117 did not have AMD, 101 had neovascular (advanced, involving the formation of new blood vessels) AMD and 2,182 had early-stage AMD.
Overall while there was no association between blue light exposure and neovascular or early AMD, blue light exposure was associated with neovascular AMD in the one-fourth of individuals with lowest antioxidant levels.
The researchers say the combination of blue light exposure and low levels of the antioxidants zeaxanthin, alpha-tocopherol (vitamin E) and vitamin C was particularly associated with a nearly four-fold odds ratio of neovascular AMD.
They recommend ensuring the intake of key antioxidants, which can be accomplished by consuming recommended dietary intake levels of vitamin C and zinc and increasing consumption of carotenoid-rich fruits and vegetables.
They also say individuals should take steps to reduce the exposure of the retina to blue light, such as wearing broad-brimmed hats and sunglasses when outdoors.
The researchers suggest that in the absence of cost-effective screening methods to identify people in the population with early AMD, that recommendations on ocular protection and diet should target the general population, especially middle-aged people.
The research appears in the current issue of Archives of Ophthalmology, one of the JAMA/Archives journals.
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