Protecting your eyes from the sun’s harmful rays is very
important if you are spending any time outdoors. Even days that
are hazy or dull require protection for our eyes. Here are a few
considerations.
Sunglasses come in a bewildering array of choices; never have
there been so many options to select from. With all the variety
you’ll want to know ahead of time what the differences are
between tinted, reflective, photochromic and polarizing lenses.
Of course the style of frame and size of lenses will be obvious
differences when shopping for sunglasses. It will also be
important to know exactly what purpose you’ll be using your
sunglasses.
Sunglasses allow for us to see easier in the bright light. Some
glasses protect against ultraviolet (UV) rays while reducing
glare and giving protection from physical damage that may be
caused to the eyes. Everyone is at risk for sun related eye
problems. People who spend long hours in the sun during work or
outdoor activity are at higher risk, than someone who is working
indoors all day long. Other people may be at higher risk of eye
damage if they are on certain medications such as; tetracycline,
birth control pills, diuretics and sulfa drugs.
Ultraviolet light can damage both the cornea and retina, so with
a good pair of sunglasses the UV can be eliminated from entering
the eye completely. Whatever sunglasses you select they should
provide the most possible UV protection possible. It’s good to
find a pair of glasses that block the sun from all angles, best
achieved with a large framed pair that wrap around the face.
Purchase sunglasses that block both the UVA and UVB rays, your
lenses should indicate this when buying them, if they don’t
specify what protection is offered it is best not to buy them.
On top of wearing sunglasses it is a good idea to wear a wide
brimmed hat.
Manufacturers use different colors of tints to produce specific
results for a variety of sunglasses needs. The color of the tint
will determine the parts of the light spectrum that will be
completely absorbed by the sunglasses. Yellow or gold tints
reduce there opposite color, which is blue while allowing other
lights to pass through. Blue lights tend to create a glare
otherwise known as blue haze. Gray tints are generally used as
an all- purpose tints reducing the overall brightness with the
least amount of color distortion. The gray lenses are a good
lens for general use and driving. Brownish and amber tints are
another example of good all-purpose glasses. They reduce glare,
absorbing blue and UV rays. Blue and violet have been shown to
contribute to cataract formation. Purple and rose tints are
great choices for water sports or golfing as they offer contrast
of objects against a blue or green background. Green tints are
another popular option as they absorb some blue light while
reducing glare.
To recognize a pair of reflective sunglasses they will be
the pair with the mirrored look. Reflective sunglasses use a
reflective coating called a half-silvered surface as it is
applied in a very sparse, thin layer. The reason the process is
called half-silvered is because the reflective molecules applied
over the glass is distributed evenly but only half the glass is
covered because of the speckled process. Thus the surface will
reflect only about half the light striking the surface, letting
the other half go through the glasses. Many styles of mirrored
glasses come in gradient forms that have additional protection
on the top part of the glasses with less protection at the
bottom of the lenses. Mirrored sunglasses are unfortunately
easily scratched so extra caution must be used to keep them
protected.
Both sunglasses and prescription eyeglasses that darken when
exposed to the sun are known as photochromic (or
photochromatic) sunglasses. The special lenses work by
using a chemical reaction with the UV radiation. The lenses have
millions of molecules of substances such as silver halide or
silver chloride. When the lenses are exposed to UV rays from the
sunlight, the molecules embedded in the lenses undergo a
chemical reaction causing them to absorb light thus darkening.
Without the UV light, the lenses go back to their original
state, it should be noted that the lenses would not darken in
the car as the windshield block out most of the ultraviolet
light. Most of the photochromic lenses do however have a bit of
tint included in them, so they will still work while driving.
It helps to know a bit about polarization to understand why
polarized sunglasses work. Polarization happens when
radiation, especially light through being transmitted,
scattered, refracted or reflected is restricted to vibrate in
only one particular direction, it can occur both naturally and
artificially. An example of natural polarization is when you
look at the ocean or a lake, the glare off the surface is a
result of the light that did not make it through the filter of
water, therefore you cannot see below the surface. What
polarized lenses does is allows the vertically polarized light
to enter from most horizontal surfaces such as highways and
water. A good test to see whether sunglasses are polarized or
not is to find a reflective surface and with the glasses in
front of the surface you want to view, slowly rotate the glasses
checking to see if the glare diminishes, if it does the glasses
are polarized. Photographers often use special polarized lenses
atop their ordinary lenses to avoid unnecessary glare from
surfaces.
There are a few extra features of sunglasses that will add to
the quality of your lenses. Scratch-resistant coating is
achieved by applying a thin durable film on the surface of the
lenses; this extends the life and safety of your glasses, as
it’s almost impossible to wear a pair of glasses with a scratch
on them while trying to see properly. Anti-reflective coating
reduces what is known as back-glare, a result of light hitting
the back of the sunglasses and bouncing into the eyes. Lastly
the most popular coating is the ultraviolet or UV coating. Some
of the most serious of eye problems can be linked to UV light,
both UVA and UVB. A good UV coating on your sunglasses will
eliminate UV radiation, it is important to check that your
glasses filter out one hundred percent of both UVA and UVB,
there should be a label on your sunglasses stating this
information.
Sunglasses come in a myriad of design, color choices and styles.
Popular designers offer glasses in prescription, men’s, women’s,
sports and junior varieties. A suggestion when purchasing
sunglasses is to try and select a pair that blocks the light
from all angles, preferably one that wraps all the way around
the face, this is if you want the ultimate eye protection. Of
course with all the choices available you’ll most importantly
select sunglasses that block both the UVA and UVB radiation in a
style that provides comfort and the right fit.
Whatever sunglasses you decide on wearing you will feel safer
knowing you are eliminating harmful rays from entering you’re
eyes. By properly taking care of you’re eyes you can hopefully
avoid problems such as cataracts, cancer of the eye or
photokeratitis (sunburn of the retina) and macular
degeneration, (which is the leading cause of blindness in
people over 65). Paying a little extra for a pair of sunglasses
with one hundred percent protection is a smart investment.