Page 57 - How It Works - Book Of Amazing Answers To Curious Questions, Volume 05-15

Technology

How do sunglasses

protect your eyes?

The sight-saving secrets of a summer style staple

eaching for our sunglasses on a bright, higher frequencies than the visible light our eyes combat glare from reflective horizontal surfaces
sunny day is second nature; we all know can perceive. They damage our eyes the same like water, sand and snow.
R that spending time in the Sun puts us at way they damage our skin, except that even in Light waves vibrate just like sound waves do.

risk of eye damage and no one enjoys the shade reflected rays pose a threat to our eyes. There’s a mish-mash of horizontal and vertical
a squinting-induced headache. Perhaps you take Sunglass lenses are made from glass, plastic components to these vibrations, but when light
them for granted, but there’s more to your or polycarbonate, with a special UV-absorbing waves strike a uniform horizontal surface
sunnies than shaded lenses. coating. A good pair blocks more than 99 per they are reflected with a strong, horizontal

Aside from lending mere mortals an air of fi lm cent of UV radiation from reaching your eyes. polarisation. The glare we experience is the jam
star mystique, sunglasses’ premier function is to Tints and mirror coatings relieve you from of light waves all vibrating in the exact same

block the Sun’s harmful ultraviolet (UV) rays. squinting by absorbing or refl ecting intense, plane. Sunglasses fitted with a polarisation

There are two types of UV rays: UVA (which dazzling light in the visible part of the spectrum film eliminate this kind of glare by only
cause skin cancer and premature ageing) and (the light we can actually see). The highest-grade enabling vertically polarised light to
UVB (responsible for sunburn). Both types have sunglasses also incorporate a polarising fi lm to pass through.
Safeguarding Anti-reflective Mirror coating Selecting the
The first line of defence;

your vision coating Lens (with UV an ultra-thin coat of
Sits closest to the eye
and reduces back-glare coating) refl ective molecules perfect pair
The ins and outs of how and internal refl ections Infused with organic deflects the light in

your sunglasses keep your off the lenses. dyes and metallic oxide bright conditions. UV damage is cumulative,
eyes from harm pigments, which absorb meaning it’s never too early – or
and reflect harmful light. too late – to start protecting your

eyes from the Sun. The most
important thing is to choose
Polarising film sunglasses that offer 100 per
Eliminates glare cent UVA and UVB protection,
from polarised light just as you would with sunscreen.
coming off The larger the frames you pick
horizontal surfaces out, and the more they hug your
like bodies of water face, the less stray light will reach
and road surfaces.
Scratch- your eyes from around the edges.
Most people mistakenly believe
resistant that the darkness of the lenses is
coating what protects their eyes. In fact,
A hard, durable some clear transparent lenses
polymer fi lm that can offer full UV protection, but
protects the surface those with a tint will cut out some
of the lenses.
portion of the light in the visible
part of the spectrum too.
Different tints offer various
advantages – for example,
ambers give sharp defi nition
while greens reduce glare and
increase contrast. Finally, if you
UVA rays intend to spend time on the
They damage the eye’s water, beach or ski slopes – invest
lens and can harm the a bit more and up your protection
sensitive retina at the level with polarising lenses.
back of the eyeball,
causing macular
degeneration and
permanent blindness.
UVB rays
These rays can destroy the outer cells of
the cornea – the eye’s protective surface
– causing pain and blurred vision.
Visible light Sunglasses with 100 per cent UVA and
The portion of the electromagnetic UVB protection are a must © Thinkstock
spectrum that we can see.

How It Works 57