Sunglasses ‘need to be changed every two years’ as light damages lenses, say scientists
Research showed two hours worth of sunlight everyday degrades the effectiveness of the lenses
TRENDY sunglasses should be replaced at least every two years as light damages the lenses, researchers warn.
The dark lenses can become lighter and lose their ability to protect against rays.
It could lead to damage to corneas and the eye’s internal structure.
The experts in Brazil called for a revision of standards and new tests on safe limits for ultraviolet filters.
Researcher Professor Liliane Ventura, of Sao Paulo University, said: “Ocular health is a serious concern worldwide.
“In some countries sunglasses standards are not quite appropriate for the ultraviolet conditions.
“The public should be more aware about ultraviolet protection as a whole.
“Sunglasses play an important role in providing safety, and their lenses should provide adequate UV filters.”
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The test exposes sunglasses to a sun simulator for 50 hours at 30cm from a 450 W lamp.
The lamp exposure is equivalent to two days in a natural environment on a summer's day, or four days in winter.