Unless you ’re the character to sport your Oakley , Gucci , or Ray - Ban sunglasses indoors , you know that shade are have in mind to protect your optic from the sun ’s harmfulultraviolet ( UV ) raysand reduce brilliance . ( Looking cool is merely a bonus . ) But if you ’re grabbing a pair you ’ve had for year , you might be marvel if their effectualness is reduced over meter . Do sunglasses ' ultraviolet radiation protection ever “ buy the farm ” ?
The answer is probably not . Here ’s why .
Most sunglasses have a clearlayerof UV coating that blocks the sun ’s rays . The finish can be over the lenses , or , in the case of more expensive sunglasses , inside them . Either room , there ’s no grounds continued sunshine exposure wears down the material .
" In general , ultraviolet protection does not degrade over sentence , " Mark Blecher , M.D. , attend MD atWills Eye Hospitalin Philadelphia , Pennsylvania , order Mental Floss . " The coatings on the Earth’s surface can scrub off , but it depends on the lineament . "
Wearers may want to check the effectivity of glasses either because they fear they ’ve been scratched or because they ’ve bought a cheaper pair and are diffident about the presence or quality of the ultraviolet light coating . Your local optic shop can perform a test , or you may do one easily at home . TakeaUV flashlightand shine it through the lens so the beam hits a newer $ 5 to $ 100 bill . If you could see the watermark on the posting , the lens are n’t obstruct the ultraviolet light light and it ’s time to throw out the glasses . If the watermark is n’t visible , you ’re good to go .
Whatever you do , do n’t opt for shades that only have tint to reduce glare and no UV coating . According to Blecher , that ’s bad than wearing no glasses . " If you ’re wearing sunglasses just to avoid glare , your pupil will distend and you ’ll get more UV exposure than if you were n’t bust any methamphetamine at all , " he says .
Without sunglasses , UV light candamagethecornea and conjunctiva , causing pterygium , or scar tissue . Over prison term , prolonged vulnerability can also accelerate cataract formation . And they ’re not stringently summertime appurtenance : If you ’re going to be out in the sun , you ’ll want to harbour your centre .
If you need a fresh couplet , ensure theyhavea 400 ultraviolet illumination label , which means the lenses block 99 percent of UV beam of light , and that they cover both UVA and UVB . ( The tint of the lenses does n’t matter when it comes to UV blocking . ) Polarized electron lens do n’t have anything to do with ultraviolet light rays , but mayreduceglare . And attempt to choose for bigger lenses , as they help cut ultraviolet radiation exposure around the optic . Tom Cruise and hisRay - Banshad the right approximation all along .
