Eye care is a serious issue and often irreversible.
A whole range of visible and invisible light comes from the sun. Some of the longest wavelengths of radiation are called radio waves, while some of the shortest are gamma and x rays. The shorter the wavelength, the higher the energy and the greater chance that these will damage our skin and eyes!
In between gamma and radio waves are Ultraviolet (UV) Light, Visible Light, and Infrared Light (IR). We cannot see Infrared, but we can feel it as radiant heat that will burn us. Of the other portion, UVA and UVB are also invisible and they can burn us too!
It is estimated that 50% of the sun’s energy reaching the earth is IR radiation, 5% is UV radiation and the remaining 45% is visible light.
Fortunately, the very harmful UVC light below the 290 nano metre wavelength are absorbed in our upper atmosphere by our ozone layer. But UVA and UVB radiation in the 290 to 400 NM pass through. The possible erosion of the ozone layer is a concern as a 2% loss of ozone will mean significant increase in skin and eye disease without protection.
Harmful Rays
UVA and UVB do reach the earths surface and UVB is a major cause of skin and eye cancers. UVA is the closest to visible light and causes cataracts and pterygium.
At the other end of the spectrum is Infrared radiation and the eye has no built ion filters to absorb IR radiation. They produce increased retinal temperature making the cornea more sensitive to UV damage.
Cloud Cover Myth
Cloud cover block a lot of visible light and IR radiation but does nothing to stop UVA and AVB reaching the earth’s surface!
Be very wary of using cheap dark glasses that do not have the UV/IR absorption or blocker filters. These glasses will just dilate your pupils and make you even more susceptible to damage!
Quality Lens Construction
All quality polarised sunglasses do come with filters that block these harmful rays. This is important as your eyes are 10 times more sensitive to UV rays than your skin and 5-10% of all skin cancers occurs around the eyes!
Now there are many reasons to wear polarized sunglasses with full UV/IR protection as these will also remove glare and allow your eyes to relax, the result is less squinting, and you’ll see more fish!
You will find that most sunglasses are tagged with a small transmittance curve on their label which shows the light over the whole spectrum that they filter out.
Manufacturers use a few different manufacturing methods to achieve this protection either by using coatings or separate layers. Regardless they all should have been tested and certified to meet Australian Standards.
