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Thopoles
There are two reasons to wear sunglasses. The first reason is if you do not like the bright sun shining in your eyes, as the dark surface of the fashion sunglasses helps to block out brilliant light and make the world appear darker. The second is the sun's ultraviolet rays can be damaging in the long run, causing all sorts of issues with your eyes including loss of vision and eye cancer. Good sun shades protect against this , as their lenses clear out the majority of the damaging UV rays.
So how do shades work? The darkening effect is an extremely simple one: taking a look at the world thru tinted lenses makes it seem darker to you - even though the effect is truly just an optical illusion, it can often help you if exposure to bright daylight tends to offer you a headache or cause you to squint.
The UV-filtering effect nevertheless , is more complicated. UV-filtering lenses are lined with special chemicals that allow light to move through them, but reflect away UV. UV rays are basically high-frequency light waves, which means that the chemical structure must be built to reflect higher frequency light while allowing thru lower frequency light. This is difficult science, and the materials needed to do it are pricey.
The most complicated sun shades of all are prescription shades. These are sun shades that not only protect from light and UV, but also work like ordinary glasses to fix your visual acuity. For this to work, it specifies that ordinary vision-correction glasses are taken, tinted and covered with UV-reflecting chemicals - a complicated three-step process.
But all the ingredients work together flawlessly, to provide sunglasses that are wearable by folks who require their vision corrected all of the time. It is even possible to buy clear coloured lenses that fit overboard of your standard glasses, effectively a do-it-yourself way of making prescription shades.
So how do shades work? The darkening effect is an extremely simple one: taking a look at the world thru tinted lenses makes it seem darker to you - even though the effect is truly just an optical illusion, it can often help you if exposure to bright daylight tends to offer you a headache or cause you to squint.
The UV-filtering effect nevertheless , is more complicated. UV-filtering lenses are lined with special chemicals that allow light to move through them, but reflect away UV. UV rays are basically high-frequency light waves, which means that the chemical structure must be built to reflect higher frequency light while allowing thru lower frequency light. This is difficult science, and the materials needed to do it are pricey.
The most complicated sun shades of all are prescription shades. These are sun shades that not only protect from light and UV, but also work like ordinary glasses to fix your visual acuity. For this to work, it specifies that ordinary vision-correction glasses are taken, tinted and covered with UV-reflecting chemicals - a complicated three-step process.
But all the ingredients work together flawlessly, to provide sunglasses that are wearable by folks who require their vision corrected all of the time. It is even possible to buy clear coloured lenses that fit overboard of your standard glasses, effectively a do-it-yourself way of making prescription shades.
About the Author:
Kay Bornham has been fanatic about sunglasses for at least 10 years, and has written many articles about shades, especially carrera sunglasses and bvlgari shades.
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