What you should know before buying sunglasses
Summer’s almost
here, so beware the brightest of sunlight! To protect your eyesight, the most
important recommendation you need to follow is to wear sunglasses that block
ultraviolet radiation whenever you go outside during daylight hours, according
to the National Eye Institute. This
is true for everyone, no matter what age, year round.
Ultraviolet radiation is the energy radiated by the sun that arrives on
Earth in wavelengths too short for us to see. Both UVA (waves that are 320 to
400 nanometers long) and UVB radiation (290 to 320 nanometers long) can be
harmful to your eyes. The fix, though, is simple. Check it out here!
You can find some of the most effective solutions to block harmful UV rays
during your outdoor times.
“The
recommendations are that eyeglasses should block UVA and UVB radiation,” said
Dr. Andrea Thau, president of the American Optometric Association.
When shopping for sunglasses, look for a tag or label that says 100% protection
against both UVA and UVB or 100% protection against UV 400.
The UV 400
designation simply means the lenses will block radiation equal to or shorter
than 400 nanometers, which covers both UVA and UVB rays, Thau said.
Thau and Dr. Justin
Bazan, a doctor of optometry and medical adviser to The Vision Council, a nonprofit trade
organization for optical industry manufacturers and suppliers, recommend
purchasing sunglasses from a reputable retailer.
These include
“eyecare provider offices, or brick-and-mortar and online department stores and
sunglass specialty shops — as they offer sunglasses that meet the necessary
standards for proper UV protection,” Bazan wrote in an email. He adds that
shoppers “should be wary when purchasing sunglasses from online auction sites,
street vendors and flea markets, as sunglasses available at these locations may
not meet the necessary standards for proper UV protection.”
That’s all good,
but does UV protection wear off over time?
It doesn’t, says
Dr. Jeff Pettey, assistant professor of ophthalmology at the Moran Center
University of Utah and a spokesman for the American Academy of Ophthalmology.
“The UV protection
is embedded,” Pettey said, explaining both the technology and the process have
changed over time, advancing far enough that “routinely, even on the cheapest
pair of glasses,” the protection is built in for life.
“In the testing
we’ve done, we’ve never had a pair of sunglasses that didn’t meet that UV
protection,” Pettey said.
He acknowledges
that in the early 1990s, tests on children’s sunglasses showed that not all
lived up to their UV protection claims, but more recently, “we just have not
seen that.”
Still, he suggests
buying from a reputable retailer just to be safe.
“There’s no
guarantee, because you can’t say for certain where your glasses are coming
from,” Pettey said, adding that there’s a test you yourself can perform at any
local optical shop that has a UV light meter.
“You can take your
glasses in and have them tested,” said Pettey. This is a handy test for when
you doubt your sunglasses have the UV protection claimed by a retail tag or if
they’re simply old and you want to make sure.
As far as a “hard
requirement,” UV protection is it, he said. Tint doesn’t matter, polarization
doesn’t matter, and although bigger is always better, “UV protection is the
essential piece.”
The inessentials,
though, may also play a role in eye health.
Beyond UV rays
Thau says there are
two parts to sunglass protection: One is non-visible radiation, and the second
has to do with visible light — how much brightness they block.
“When you’re in the
bright sun, like the beach, you do want something 75% or darker to block you
from visible light,” Thau said. Too much exposure to visible light “does bleach
your receptors, and some studies have indicated it can impair your night vision
and your color vision perception.”
Yet blocking
visible light has a downside if your sunglasses are not up to UV snuff,
suggests Dr. James H. Diaz, an environmental medicine specialist and
anesthesiologist.
“The darker the
sunglass lenses, the more the pupils will dilate and allow more UV light to
enter the eye,” Diaz wrote in an email. This is true of blue light, which
ranges in length from 400 to 440 nanometers.
“The longer the
retinas are exposed to unfiltered blue light, the greater the risk of macular
degeneration,” Diaz said. However, the National Eye Institute does not list
protection against blue light as necessary when purchasing sunglasses. In
fact, research has shown blue
light exposure is good for us, as it helps regulate our circadian rhythms and
so affects both mood and cognition.
“Orange and yellow
lenses provide the best protection from blue light, and blue and purple lenses
provide the least protection,” Diaz said.
Thau noted color is
not crucial in protecting eye health. “Most popular colors are gray, green and
brown. They are the least distorting for color perception, with gray being the
most neutral,” she said.
People who have
color vision deficiencies generally find that they see much better with brown
lenses, while “green seems to give more contrast,” said Thau.
Whether you opt to
filter out blue light or not, a good pair of UV-blocking sunglasses can protect
both your short-term and long-term health.
Protect your thin skin
“Skin around the
eyelid is the thinnest in the body, so it is susceptible to skin cancers,” Thau
said. This thin skin is most likely to develop basal cell and squamous cell
cancers, so the recommendation is to wear the largest pair of sunglasses
possible to protect the eyelids and surrounding skin.
Meanwhile, Pettey
warns that cancers of the eye itself, including squamous cell carcinomas and
malignant melanomas, also can result from sun exposure.
“The same damage
that occurs to our skin occurs to the eye,” he said: specifically “eye burn,” a
form of short-term damage similar to a sunburn.
Thau says sun
exposure can also cause photokeratitis, an inflammation of the cornea, with
temporary symptoms of blurry vision, light sensitivity and a burning or gritty
sensation. Too much sunlight may also lead to a thickening and/or yellowing of
the conjunctiva, the membrane covering the eye. Though unsightly and annoying —
your eyes will feel too dry when this happens — this doesn’t cause blindness,
says Thau.
Other conditions
caused by too much unprotected time in the sun may have longer-term
consequences, according to Pettey. Pterygium, for
instance, is a growth of fleshy tissue that can cover part of the cornea and
hurt your vision. This is sometimes called “surfer’s eye.”
“Inside of the eye,
as far as function, increased UV light leads to increased progression of
cataracts and also likely increased progression of macular degeneration, both
of which are conditions that cause loss of sight,” Pettey said.
Thau says the
latter is the more serious of the two complications.
“Cataracts can be
removed surgically, but macular degeneration is yours for life,” she said. “It
literally causes damage to the photo receptors. It’s like damaging film in a
camera, and you cannot replace the film.”
One other long-term
danger of looking directly at the sun is solar retinopathy. Just like your
mother told you, don’t ever look directly at a solar eclipse, such as the
one coming August 21.
“If you were to
look at that level of radiation, even for a few seconds, without the brightness
of the light telling you to look away because it would be painful, you can
actually cause burns on the retina in the back,” Thau said. These burns cause
permanent damage to your sight, and regular sunglasses are not enough
protection for a solar eclipse.
Though the sun is
the main cause of UV radiation damage, artificial sources such as tanning beds,
lasers and welding machines also produce UV radiation that might damage vision.
One other
consideration at least for some is their location on the globe, Diaz said.
Polarized lenses
“We have more sunny
days in the South, especially in Florida, and the West, especially in
California, than in other areas of the US, and therefore, we see more
sun-related injuries,” said Diaz, who has researched this topic. Naturally, this is also
true for the sunniest spots around the globe.
“Another problem in
the coastal South and all coastal areas is the reflected magnification of UV
radiation off of surface waters,” Diaz said. UV-blocking sunglasses protect
against these reflections, but there is a risk of the same complications that
result from direct sunlight.
Beyond the standard
UV recommendations, does polarization matter?
“I like to fish,
and polarized lenses will reduce reflection and glare off surface waters and
allow one to see at a greater depth,” Diaz said.
Thau says this is
not mandatory, “it’s just an optional add-on benefit you can have.”
Though most of us
are concerned with eye health, the Vision Council reports that only 31% of
Americans always wear sunglasses when outside.
They’re not merely
a fashion statement, insists Thau, but if that gets you to wear them, go with
it. She herself owns five pairs and has been known to put them on even when
sitting in a bright room.
To be safest, Thau
recommends that an annual comprehensive eye examination with a credentialed
doctor to learn more about eye health and which sunglasses might be most
beneficial in any given circumstance.
“It’s also
important for children to start with some protection early, because it’s
cumulative damage over time,” Thau said. “My family does not walk out the door
without their sunglasses on, except at night.”
Want to send us a story? SMS to 25170 or WhatsApp 0743570000 or Submit on Citizen Digital or email wananchi@royalmedia.co.ke
Comments
No comments yet.
Leave a Comment