By Dr. Mercola
Nearsightedness is incredibly common, affecting an estimated 40
percent of Americans and up to 90 percentof young adults in Asian
countries.1 According to research published in 2009, rates of nearsightedness in the U.S. have risen by 66 percent since the early 1970s.2
A 2015 study estimated up to one-third of the world's population may
be nearsighted by the end of the decade — that's 2.5 billion people.3 The following year, a meta-analysis of 145 studies predicted nearly half of the world will be nearsighted by the year 2050.4
Just what might be causing this rapid mass-deterioration of vision?
One longstanding theory was that excessive reading at close distance
(particularly in poor lighting) could lead to nearsightedness by
altering growth and shape of the eyeball.
As computers and smartphones grew in popularity, squinting at computer screens has received a majority of the blame.
The "bookworm theory" first emerged centuries ago when German
astronomer Johannes Kepler claimed his studies caused his
nearsightedness. It seemed plausible enough, especially as rates of the
condition skyrocketed in regions like Shanghai, where teens spend about
14 hours a week on homework.5
However, once investigated further, the bookwork theory came up
short. When researchers looked at number of books read per week or hours
spent using a computer among children in Singapore, no significant link
to nearsightedness was actually found.6
According to the authors, "neither reading nor parental myopia
history were associated with values for anterior chamber depth, corneal
curvature, or lens thickness."
They went on to suggest that "corneal curvature and lens thickness
may be subject to unrelated postnatal growth control mechanisms."
Interestingly, a number of studies now suggest one of these control
mechanisms might be sun exposure.
What Causes Nearsightedness?
Nearsightedness (myopia), is a vision problem in which close objects
appear clear but distant objects are blurry. This condition is thought
to be caused by refractive errors in your eye. Refraction is the bending
of light as it passes through one object to another.
When light rays are refracted through your eye's cornea and lens,
they become focused on the retina, which then converts the light into
messages sent through the optic nerve to your brain, which then
interprets the messages into images.
Refractive errors occur when the shape of your eye prevents light
from focusing properly on your retina. This can occur by changes in the
shape of your eye, such as the length of your eyeball or shape of your
cornea, and/or changes in your lens due to aging. But what exactly is
responsible for these changes?
Two studies, the first published in 20077 and the second in 2008,8
found that rates of nearsightedness in children appeared to be closely
linked to the amount of time spent outdoors. The greater the number of
hours spent playing outside, the lower the risk of nearsightedness.
In other words, keeping kids indoors and/or instilling a fear of sun
exposure (for skin cancer reasons) may be at the heart of the world's
growing myopia problem. Remarkably, according to a British survey, 75
percent of children in the U.K. spend less time outdoors than prison
inmates!9
Sun Exposure Needed for Optimal Vision
Most recently, British researchers investigated the connection between the time spent outdoors and vision among the elderly.10,11,12 As reported by The New York Times:13
"Researchers … gave vision exams to more than 3,100 older
European men and women and interviewed them at length about their
education, careers and how often they remembered being outside during
various stages of their lives.
This biographical information was then cross-referenced with
historical data about sunlight, originally compiled for research on skin
cancer and other conditions.
Strong correlations were found between current eyesight and
volunteers' lifetime exposure to sunlight, above all UVB radiation …
Those who had gotten the most sun, particularly between the ages
of 14 and 19, were about 25 percent less likely to have developed myopia
by middle age. Exposure to sunlight up to the age of 30 also conferred a
protective benefit."
Importantly, this relationship remained even after controlling for
time spent reading, showing that gazing at screens or books is more or
less unrelated to myopia, while sun exposure appears to be a primary
factor. The question is how does light actually affect the structure of
the eye?
Since blood tests were drawn, they could conclude that the reduction in myopia was NOT related to vitamin D.
As noted by lead author Katie Williams, a clinical research fellow at
King's College London, "People with myopia have long eyeballs, so there
must be something in sunlight that affects how the eye grows,
especially in childhood."
On a side note, they did find a correlation between myopia and lutein
concentrations in the blood. Lutein, found in egg yolks and leafy
greens, is known for its protective influence on eyesight and the
prevention of age-related macular degeneration (AMD).
Here, those with the highest levels of lutein had a 43 percent lower risk of myopia compared to those with the lowest levels.
As for how sunlight affects eye development, animal research14
published in 2010 suggests bright light exposure helps protect your
eyes by stimulating the growth of key elements in the retina, and by
increasing the functioning of antioxidants in the eye.
An even earlier study, published in 2008,15
showed that infrared light — found in sunlight — activates cytochrome
oxidase, a photosenstive molecule located in your mitochondria.
Activating this molecule led to increased cellular activity in the
retina, and an increase in antioxidant properties.
Meanwhile, research has shown that cytochrome C oxidase deficiency is
a factor in age-related macular degeneration (AMD), which is a primary
cause of blindness.16
Outdoor Playtime May Significantly Reduce Your Child's Risk of Myopia
Another recent study,17
this one from Canada, found that spending just one more hour outdoors
each week may decrease a child's risk of myopia by 14 percent.
To reach this conclusion, the scientists conducted eye exams on 166
first through eighth grade students. In grade 1, 6 percent had myopia.
By age 13, that percentage skyrocketed to 29 percent.
The parents were then interviewed to ascertain the amount of time
each child typically spent outdoors each week. Again, this turned out to
be a major predictive factor for myopia.
Previous research by Ian Morgan of the Australian National University
suggests that exposure to light levels of at least 10,000 lux for three
hours a day may protect children from nearsightedness.18
This is the amount of light you would be exposed to on a bright
summer day. An indoor classroom, by comparison, would only provide about
500 lux.
Yet another study showed that by encouraging Taiwanese children at
one school to spend their daily 80-minute break outdoors, rates of
myopia dropped to 8 percent compared to 18 percent at another nearby
school.19
According to optometrist Donald Mutti, children who are genetically
predisposed to nearsightedness are 300 percent less likely to need
glasses if they spend at least 14 hours a week outdoors.20
In Singapore, public health campaigns have even been introduced
encouraging children to get outdoors to prevent nearsightedness. The
slogan? "Keep myopia away, go outdoors and play!"21
Indeed, it seems clear that the more time children spend outdoors,
the lower their risk of nearsightedness becomes, and the more we learn
about the influence of sunlight on human biology and health, the more
this connection makes sense.
Bright Light Is Important for Overall Health
When full-spectrum light (i.e. sunlight) enters your eyes, it not
only goes to your visual centers enabling you to see, it also goes to
your brain's hypothalamus where it impacts your entire body. For
starters, your hypothalamus controls body temperature, hunger and
thirst, water balance and blood pressure. It also controls your body's
master gland, the pituitary, which secretes many essential hormones,
including those that influence your mood.
Your "body clock" is also housed in tiny centers located in the
hypothalamus, controlling your body's circadian rhythm. This
light-sensitive rhythm is dependent on natural cycles of light and
darkness, to function optimally. Consequently, anything that disrupts
these rhythms, like inadequate sunlight exposure to your body (including
your eyes) or chronic exposure to unopposed blue light from artificial
lights, has a far-reaching impact on your body's ability to function.
Some experts even believe that "malillumination"
to light is what malnutrition is to food. The best way to get exposure
to healthy full-spectrum light is to do it the way nature intended, by
going outside, exposing your bare skin — and "bare" eyes — to the sun on
a regular basis.
Sunlight Is Also Important for the Prevention of Blindness
As explained by Dr. Alexander Wunsch, a world class expert on
photobiology, full-spectrum light such as sunlight is also a significant
factor in blindness and optimal health. More specifically, the
widespread use of energy efficient light-emitting diodes (LEDs)
may be setting the stage for an avalanche of AMD in coming decades. The
reason for this is because LED lighting has no near-infrared light,
emitting primarily blue light, and this has biological consequences that
impair your vision over time.
The heat generated by incandescent light bulbs (which is infrared
radiation) is actually highly beneficial to your health, and hence worth
the extra energy cost. In your eyes, the near-infrared light range
primes the cells in your retina for repair and regeneration from the
damage blue light causes in the retina. Meanwhile, LEDs, which have
virtually no infrared and an excess of blue light, generates reactive
oxygen species (ROS) instead.
You do need some blue light, especially in the morning for melatonin
production, but you need it to be balanced with the healing and
repairing red and near-infrared frequencies, like it is in natural
sunlight.
This explains why LEDs are so harmful for your eyes and overall
health. The same applies to electronic screens such as TVs, computers,
tablets and smartphones. They all emit primarily blue light, and the
excess ROS generation may have a great deal to do with the deterioration
of vision. The blue light is also deleterious for your circadian
rhythm. Electronic screens should be avoided at least a couple of hours
before bedtime to avoid suppressing melatonin production.
Interestingly, research22
shows that infrared light exposure may even reverse AMD. Even more
remarkable, infrared light over the thyroid area has been shown to
reverse hypothyroidism! It seems the more we learn about light, the more
crucial it appears to be for biological functioning and optimal health.
It's important to realize that light is actually a significant part of
the equation for biological energy production, specifically at the mitochondrial ATP level. Hence it affects your overall health, not just your eyes.
Importantly, full-spectrum light — light that includes the
near-infrared spectrum (750 to 1400 nm) — generates structured water in
your cells, which plays an important role in biological functioning,
including your cardiovascular function. To learn more about this, please
see my interview with Dr. Thomas Cowan. I also discuss this in my recent article, "Water Supports Health in Ways You May Never Have Suspected."
In summary, to protect your eyesight and overall health, be sure to
get bright sun exposure especially in the early part of the day and,
when indoors, use clear (not white-coated) incandescent light bulbs in
areas where you spend most of your time. Candles can also be used,
especially at night, and are even better and healthier than
incandescents.
I also believe it is imperative to use blue-blocking glasses
after sunset, unless the only light exposure you have is candles. Once
you have your glasses on, it doesn't matter what kind of light bulbs you
use.
Candles — Another Healthy Light Alternative
Candles are even a better light source than incandescent bulbs, as
there is no electricity involved and is the light our ancestors have
used for many millennia, so our bodies are already adapted to it. The
only problem is that you need to be careful about using just any old
candle, as most are toxic.
As you may or may not know, many candles available today are riddled
with toxins, especially paraffin candles. Did you know that paraffin is a
petroleum by-product created when crude oil is refined into gasoline?
Further, a number of known carcinogens and toxins are added to the
paraffin to increase burn stability, not including the potential for
lead added to wicks, and soot invading your lungs.
To complicate matters, a lot of candles, both paraffin and soy, are
corrupted with toxic dyes and fragrances; some soy candles are only
partially soy with many other additives and/or use GMO soy.
The candles I use are non-GMO soy, which is clean burning without
harmful fumes or soot, is grown in the U.S. and is both sustainable and
renewable. They're also completely free of dyes. The soy in these
candles is not tested on animals and is free of herbicides and
pesticides.
It's also kosher, 100 percent natural and biodegradable. The fragrances
are body safe, phthalate- and paraben-free, and contain no California
prop 65 ingredients. You can search online for healthy candles, but if
you like, you can use the ones I found at www.circleoflifefarms.com.
This is not an affiliate link and I earn no commissions on these
candles; I just thought you might benefit from the ones I now use in my
home.
How to Make Digital Screens Healthier
When it comes to computer screens, it is important to reduce the
correlated color temperature down to 2,700 K — even during the day, not
just at night. It's even better to set it below 2000K or even 1000K.
Many use f.lux to do this, but I have a great surprise for you as I have
found a FAR better alternative that was created by DanielGeorgiev, a 22-year-old Bulgarian programmer that Ben Greenfield introduced to me.
He was using F.lux but became frustrated with the controls. He
attempted to contact the F.lux programmers but they never got back to
him, so he created a massively superior alternative called Iris. It is
free, but you'll want to pay the $2 and reward him with the donation.
You can purchase the $2 Iris mini software here.
Iris is better because it has three levels of blue blocking below
f.lux: dim incandescent, candle and ember. I have been using ember
after sunset and measured the spectrum and it blocked nearly all light
below 550 nm, which is spectacular, as you can see in the image below
when I measured it on my monitor in the ember setting. When I measured
the f.lux at its lowest setting of incandescent it showed loads of blue
light coming through, as you can clearly see in the second image below.
So, if you are serious about protecting your vision you will abandon
f.lux software and switch to Iris. I have been using it for about three
months now, and even though I have very good vision at the age of 62 and
don't require reading glasses, my visual acuity seems to have
dramatically increased. I believe this is because I am not exposing my
retina to the damaging effects of blue light after sunset. Iris Software: F.lux Software:
Diet Also Plays a Role in Nearsightedness and AMD
When it comes to protecting your vision, your diet also plays an
important role, as your eyes need certain nutrients in order to function
properly. Dark leafy greens are particularly important, as they're rich
in carotenoids like zeaxanthin and lutein. Zeaxanthin is an antioxidant
carotenoid found in your retina, but it cannot be made by your body, so
you must get it from your diet.
Other important nutrients include animal-based omega-3 fats, vitamins A, C and E, and zinc.23 AMD, as well as cataracts, are largely driven by free radical damage, and may in many cases be largely preventable through antioxidant-rich foods such as:
Bioflavonoids (found in tea, cherries, and citrus fruits)
Your diet can also influence your risk for nearsightedness. According
to Loren Cordain, an evolutionary biologist at the Colorado State
University in Fort Collins, elevated insulin levels affect the
development of your eyeball, making it abnormally long, thereby causing
near-sightedness.24
Cordain found that when hunter-gatherer societies change their
lifestyles and introduce grains and carbohydrates, they rapidly develop
(within a single generation) myopia rates that equal or exceed those in
western societies.
The reason for this is because high insulin levels from excess carbohydrates
can increase insulin resistance and disturb the delicate choreography
that normally coordinates eyeball lengthening and lens growth. And if
the eyeball grows too long, the lens can no longer flatten itself enough
to focus a sharp image on the retina.
This theory is also consistent with observations that you're more
likely to develop myopia if you are overweight or have adult-onset
diabetes, both of which involve elevated insulin levels. Following my nutrition plan
will help normalize your insulin level by reducing, or eliminating,
excess sugar and processed grains from your diet. To learn more about
which foods can help safeguard your vision, please see my previous
articles, "Eat Right to Protect Your Eyesight," and "The Best Foods for Healthy Eyes."
How the Bates Method May Improve Your Nearsightedness
If you're already nearsighted, all is not lost. According to Greg
Marsh, a certified natural vision coach, clear vision is achievable even
if you're already wearing strong corrective lenses. The method Greg
teaches was initially conceived by Dr. William H. Bates, over 100 years
ago.
A board-certified ophthalmologist at the top of his field, Dr. Bates
taught his method to many, and it was so effective that it ended up
being banned in New York after the optometrists lobbied the local
politicians. So how does the Bates Method work? Marsh explains:
"Basically, there are six muscles on the outside of your eye, and
they're moving it around ... Ideally, these muscles are easily
following visual interests ... The problem is — it could be for
emotional reasons, physical stress, or whatever — you start to strain.
Once you start to strain, your vision starts to go."
The action of straining essentially squeezes your eyeballs,
contorting them. This makes your vision blurry, as it alters where the
field of vision "lands" on your retina. Now you have three basic
choices:
Find out what's stressing you, making you strain. Let it go, relax,
and get your vision back. Bates developed ingenious tools for doing just
that
Get laser in-situ keratomileusis (LASIK), which permanently alters your focal length
Get corrective lenses. The problem with corrective lenses is that now you're creating permanent strain
The Bates Method isn't really an exercise; it's more of a mental
approach. It's also worth noting that the Bates Method is clearly NOT a
medical approach. You still need to see your regular eye doctor for
checkups. One of the most famous Bates Method techniques is palming.
Look around and notice the level of clarity of your vision at present.
Then, simply place the center of your palms over your eyes. Relax
your shoulders. You may want to lean forward onto a table or a stack of
pillows, to facilitate relaxation. Relax like this for at least two
minutes. Then remove your hands, open your eyes, and notice whether
anything looks clearer. Usually, it will.
The Bates Method is really quite simple, yet it requires patience and
a certain amount of finesse. Remember, the goal is not to "train" or
exercise your eyes to make them stronger. The goal is to relax them.
Greg's program provides thorough instructions that can help you get
there. Also, remember that your mindset is important.
Bates was also a proponent of sunning the eyes to help correct vision problems,25
and recent research suggests he was on the right track 100 years ago.
It just goes to show that, as humans, we cannot extract ourselves too
far from the natural world.
Indeed, we depend on the natural order of things to thrive, and that
includes being exposed to sunlight during the daytime, and avoiding
light exposure once the sun has set. Altering this natural order has
consequences for our health, including but certainly not limited to our
vision.
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