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Long-term exposure to ultraviolet radiation in sunlight is known to increase the risk of cataracts later in life. A new study suggests how that might happen.
Researchers at Case Western Reserve University, Cleveland, Ohio, and in Ahmedabad, India, found that UV rays can damage proteins in the eye’s lens by the process of glycation (bonding with a sugar molecule), causing them to clump together and scatter light rather than transmitting it to the retina. Glycation occurs in cataracts and in cells subjected to oxidative stress. In the case of cataracts, UV light apparently takes the place of oxygen, which isn’t present in lens cells, to set off damaging oxidative reactions.
When the researchers examined the effect of UVA radiation on amino acid derivatives called kynurenines in lens cells, they discovered that UVA rays initiated a reaction that led to protein glycation without oxygen being present. The relative impact of UVA and UVB radiation on cataracts isn’t clear, but UVA rays penetrate farther into the body and so may have a better chance of entering the lens.
By clarifying how UV radiation can contribute to cataract formation, the study reinforces the need to protect eyes from sunlight. This is especially true for children and adolescents whose developing lenses take in significantly more UV light than adults. About 25% of children’s lifetime UV exposure takes place before 18 years of age.
The Vision Council’s 2014 Sun Protection Survey found that less than half of parents (48%) make their children use eye protection when outdoors, where UV exposure can result from reflection off water, snow, dry sand or concrete, even grass. The Council website offers information and tools for protecting kids from UV exposure and suggestions for parents to consider before purchasing sunglasses for their children.
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