UV light exposure over time can cause permanent eye damage! For this reason, you must not compromise on the UV absorption properties of your sunglasses.
Sunglasses must block 99-100% of UVA and UVB radiation, and 75-90% of visible light.
Understand terminology and labels – “UV
absorption up to 400nm” is the same as 100% UV absorption;
“Meets ANSI UV Requirements” or “special
purpose” indicates the sunglasses block at least 99% of UV rays.
Sunglasses labeled “cosmetic” block about 70% of UV rays.
Be wary of labels that claim “Provides UV
Protection” without specifying exactly what percentage of UV rays
Some sunglasses are certified with the AOA Seal of Acceptance for UV
Absorbers and Blockers from the American Optometric Association, which
ensures that you are getting the recommended maximum 99-100% UV
radiation protection, and 75-90% of visible light protection.
the American National Standards Institute, has established minimum
standards for sunglasses to block 50% UVA and 70% UVB protection (ANSI
Z80.3). This is minimal; you want the 99-100% protection recommended
recognized standards for UV blockage
include ISO 8980-3, EN 1836 and AS/NZS 1067.
Darker doesn't necessarily
mean greater UV protection, but darkness
should be an important consideration for the activity for which the
sunglasses will be worn. E.g., you wouldn’t wear light shades
Both glass and plastic absorb
some UV radiation, but UV absorption
is greatly improved by the application of a chemical to the lens
Maximum UV protection is
ensured with wrap-around frames, which
protect both the front and sides of your eyes from UV/light
Sunglasses that do not
adequately filter out UV light can actually
cause more eye damage than wearing no sunglasses at all, because the
pupils dilate, letting in more harmful UV rays.
Do NOT buy toy sunglasses for
children that don’t have the
protection recommended above. Children are more prone to sun damage to
the eyes as their pupils are usually larger than adults and the lenses
of their eyes are clearer. Eye damage is cumulative, so start toddlers
off early in life with the best UV protection!
Even the best sunglasses cannot protect your eyes
from certain intense light sources. Arc welding, tanning lights,
snowfields or looking directly at the sun (especially during a solar
eclipse) can damage your eyes! Looking at any of these light sources
without adequate protection can cause a painful corneal condition
called photokeratitis or even a permanent loss of vision! Do NOT rely
upon sunglasses to protect your eyes under the above conditions. You
MUST wear appropriate eye protection for these types of specialized
activities or risk permanent damage to your eyes!
– the best, most popular, all-purpose color.
Virtually no color distortion; depth perception is unaffected. Offers
good protection against glare. Excellent absorption of UV and infrared
– Similar performance to gray. Filters some
‘blue light’, light at the violet-blue end of the
often found in fog, haze, or low light environments. Reduces glare.
Green offers the highest contrast of any tint. Very popular.
– good general purpose tint, but
increases color distortion. Depth perception is enhanced. Particularly
effective in absorbing harmful ‘blue light’, in
UV rays. Blue, or Blu Blockers are a patented version of sunglasses
that utilize this ‘blue light’ property inherent in
brown/amber tints. Most popular color for driving, but also favorable
for boating, skiing, and general use.
– depth perception is enhanced, but so
is color distortion. Reduces the amount of ‘blue
tending to make images bright and sharp. Good for snow activities. A
special coating must be applied to yellow lenses to absorb infrared
– offer the best contrast of objects
against a green or blue background, so they’re good for
or water skiing. Often selected as a stylistic preference and has a
softer, warmer feel over a long period of time.
– claimed by some to be good for playing
tennis, as blue lenses let in blue and green light and may allow you to
see a tennis ball better. Lets in more damaging ‘blue
light’, so some professionals advise against. Often a
– a uniform decrease in the tint of
a lens, generally from the top (darker tint) to the bottom (lighter
tint). Useful for driving because they don't dim your view of the
dashboard, but not as good on snow or at the beach.
– tinting is darker at the top and
bottom, but lighter in the middle. Preferred for sports where light
reflects up off the water or snow, such as sailing or skiing. Not
recommended for driving, because they make the dashboard appear dim.
The three most common lens materials in use today are crown glass,
CR-39 plastic, and polycarbonate plastic lenses. There are also other
manufacturer-developed materials, such as Oakley’s Plutonite
plastic. All sunglasses must meet impact standards set by the Federal
Food and Drug Administration. No lens is truly unbreakable, but plastic
lenses are less likely than glass lenses to shatter when struck by a
hard object, such as a stone. Most non-prescription sunglass lenses are
glass – soda-lime
glass used for lenses and
prisms; is ground and polished to exacting and consistent standards to
virtually eliminate distortion. Highly scratch resistant, but is
heavier and is more vulnerable to breakage on impact than its non-glass
counterparts. Superior optical quality.
plastic – made from a
hard resin with
excellent optical quality. Good impact resistance. Strong and
is a synthetic material, lighter and more
impact resistant than its glass and plastic counterparts, but with
slightly reduced optical quality. Although a tough material, it
scratches relatively easily, so look for them with scratch-resistant
coatings. Polycarbonate lenses are a must for your sunglasses if you
participate in potentially eye hazardous work or sports. Also an
excellent choice for active children.
such as Oakley’s Plutonite
are available as well.
protection is obtained primarily
by the application of
a chemical to the surface of the sunglasses.
– clear, hard films are applied
to plastic lenses to improve durability. Typical films are DLC
(diamond-like carbon) and polycrystalline diamond.
– a common problem with sunglasses
is back glare, or light hitting the back of the lens and reflecting
into the eyes. An anti-reflective coating is applied to the lenses to
reduce this glare.
/ Mirror – a mirror
coating is applied to
the outside surface of the lenses to reflect light.
Mirroring today is commonly applied in a half-silvered, single gradient
fashion. This means that the mirroring is not only translucent, but
decreases in silvering from the top to bottom of the lens, reflecting
more light from above, while allowing light from below to enter. Often
a stylistic preference (looks tough, authoritative, intimidating, and
mysterious, like law enforcement). Popular for world poker and other
activities in reflecting overhead light and concealing your eyes. Best
for intense glare conditions like snow and water. Note the reflective
properties of mirrored sunglasses tend to cause your nose to sunburn
faster than with no mirroring, as it receives both direct and reflected
Another issue is the mirror coating is prone to scratching, reducing
aesthetics and performance.
sheeting – a property
of shedding water in
sheets, rather than beads or drops, for improved visibility in wet
conditions (rain, motorcycling, waterfalls, lakes, oceans, etc.).
Achieved through a combination of very smooth surface and application
of a special lens coating.
-- Light waves from a natural light source,
the sun, or from an artificial light source, such as an incandescent
light bulb, vibrate and radiate outward in all directions. When their
vibrations are aligned along the same polar plane, the light is said to
be polarized. When not aligned, they are said to be randomly polarized.
Polarization can occur either naturally or artificially. An
illustration of natural polarization is the reflected glare off the
surface of a lake. The glare you see is reflected because it does not
penetrate the ‘filter’ of the water. This glare
why it is difficult, if not impossible to see anything below the
surface, even when the water is very clear.
Glare produces eyestrain, discomfort, and results in squinting.
Sunglass tinting alone can not address the problem of glare. But
polarized filters selectively absorb the reflected glare while passing,
or transmitting useful light to your eyes. Polarization can be adjusted
so the light passed is at a comfortable and useful light level.
Polarization has been used in over one billion pair of sunglasses over
the last 50 years and its use remains widespread today. Unlike the
earliest versions, today’s versions also block out
light and can selectively attenuate harmful blue light.
Polarizing lenses are available in two main versions: neutral gray
which absorbs all colors approximately equally and blue absorbers which
preferentially absorb blue light. However blue absorbers should not
totally eliminate blue light because that would impede detection of
blue objects. Polarized lenses
are fabulous for many selected activities, but
not for all:
experts debate the appropriate use of
polarized lenses for snow-covered surfaces. While they can reduce the
intense glare from sunlight off of snow, for downhill skiers they may
not provide the ‘useful’ glare and contrast the eye
to distinguish smooth snow from ice patches or moguls.
LCDs (liquid crystal
displays), when viewed through polarized
lenses from a certain angle, can be invisible.
Distortions may be
experienced when looking through laminated
glass or polycarbonate through polarized lenses.
lenses are NOT recommended for aviation. The
flexing of an aircraft canopy can result in the rapid and frequent
appearance and disappearance of polarized fields. If looking through
the airplane canopy with polarized lenses, the effect is one of being
blinded to light from those areas, which could be legitimate reflection
from another aircraft! The same holds true of aircraft instrumentation,
many of which are equipped with polarized filters.
So…when SHOULD you
use polarized sunglasses?
there are horizontal surfaces producing unwanted glare.
activities to 'get polarized' include: driving; motorcycling; fishing;
waterskiing; in-line skating; biking; jogging; around lakes, oceans,
and sandy or desert areas; and many such others. And
when SHOULDN'T you use polarized sunglasses?
While participating in activities where the presence of horizontal
surfaces is minimal, or where their use will filter out
‘essential’ glare, as in aviation.
earlier, a polarized
may not be suitable for downhill skiing.
/ photochromatic –
developed by Corning
in the late 1960s and later popularized by Transitions® lenses, they have
special additives (silver chloride, silver halide) which are reactive
to UV rays in sunlight, causing the lenses to darken/lighten in
proportion to the intensity of the rays. Some also react to temperature
changes. Still commonly referred to generically as
lenses. Due, in part, to technology advances, their use is growing
Early versions of photochromic shades were made out of glass and were
relatively heavy, but today are available in various lightweight
materials such as polycarbonate. Modern photochromics are superior to
the older versions in uniformity of color, and improved properties,
e.g., darkening response in spaces where UV is filtered, such as behind
the windshield of an automobile.
A great everyday selection, as they can serve as both prescription and
sunglasses in one, and can be worn indoors and out. They automatically
protect against UV, but not all plastic photochromic lenses block 100%
UVA and UVB radiation. Also, if frequently in/out of the sun, they may
not change tint fast enough for the wearer’s liking. Most of
darkening takes about 30 seconds, while the lightening can take up to
Current photochromic lenses on the market, shown by manufacturer,
& PhotoBrown -- the
originals, still on
the market after 35 years.
& Dark-- lighter in
weight (up to 30%) and
thinner than traditional glass lenses. Claimed to transition from clear
to dark in 60 seconds. Available in gray and brown.
-- Corning's newest. Lens offerings are
mid-index gray and brown plastic. 60 second transition time.
-- similar to ColorMatic Extras. Can also be
-- unique from the others in that they are
photochromatic lenses. Available in
glass and plastic.
Extra -- also a mid-index
photochromic line of sunglasses. Can be tinted to adjust color or
darken the lenses.
-- unique, funky lenses that begin as one color
and change to a different color, e.g., yellow to orange, teal to green,
red to purple.
-- currently being test marketed, these are
only intended for outdoor use. Change from medium to dark green when
exposed to light.