Screen time.
If you’re spending a lot of time in front of a laptop or a smartphone, you might be doing irreparable damage to your eyes.
In today’s video, we’re going to be talking about a type of light that can cause macular degeneration…
and give you some strategies for preventing that damage…
without giving up that valuable screen time.
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Age-related macular degeneration, also known as AMD or ARMD,
is the main cause of central vision loss for those over the age of 50.
It’s a progressive condition in which light-sensing cells in the eye’s retina called photoreceptors,
start to malfunction, and eventually can cease working altogether.
Often, people with AMD will notice that straight lines appear wavy,
and other symptoms can include blurred text,
often with dark or empty spaces that may block the center of vision.
AMD can make activities that require a high degree of visual acuity, like driving or reading,
to become increasingly more difficult.
While macular degeneration rarely results in complete blindness, it’s common enough that worldwide,
it’s been estimated that perhaps a million people are totally blind due to advanced AMD.
It’s the fourth most common cause of blindness, after cataracts, preterm birth, and glaucoma.
And it’s the leading cause of severe, irreversible loss of vision in people over the age of 60.
The odds of developing are related macular degeneration between the ages of 50 and 60 is only about four tenths of one percent.
But by the time the age of 80 is achieved, that chance goes up to 12%.
And continues rising from there.
While it’s not clear what triggers AMD,
hardening of the arteries that supply blood to the retina has been getting a lot of focus.
Over time, this can deprive the tissues of the eye of oxygen and other nutrients that are required to protect it.
There are several risk factors for AMD, with “Aging” leading the pack.
A family history of AMD can also be a risk factor,
or if you’re a smoker or have hypertension, atherosclerosis, high cholesterol, are obese or have a high fat intake.
But there’s another risk factor that’s huge, and that’s what we’re going to be talking about today.
And that’s exposure to either ultraviolet light, or to high-energy visible blue light.
This is the blue light that’s emitted by the LEDs in flatscreen TVs, smartphones, computer or laptop screens, notebooks and e-readers.
To understand how this occurs, we going to have to take a look at the science…
in this case, the biology of the eye.
The principle structures of the eye, for the purposes of this discussion, are the lens, the cornea, the iris and the retina.
When we focus directly on an object, the image of that object appears on a small area of the retina directly behind the lens, called the macula.
The macula is very dense in photoreceptors, and it’s where most of our high-acuity, color vision takes place.
AMD can take two different forms, called wet and dry.
The wet form affects about 15% of patients with AMD
and is caused by the growth of abnormal blood vessels under the retina.
This can lead to bleeding, hemorrhaging and scarring
and results in a rapid and more severe progression of the disease.
Fortunately, about 70% of patients with the wet form of AMD can be treated with laser photocoagulation
to help stabilize the vision and to limit the further growth of abnormal blood vessels.
The dry form affects about 85% of patients and is less progressive and not as severe as the wet form.
As we age, photoreceptors in the macula can become damaged or even die off,
although at first, there are probably no noticeable symptoms.
But as the disease progresses, symptoms appear and become noticeably worse over time.
And there is no treatment that can successfully reverse the dry form of this condition, or return vision that is already lost.
The photoreceptors of the retina can’t be replaced or regenerated.
Once they’re gone, that’s it. They’re gone.
But it appears that it can be prevented.
One of the biggest risk factors for AMD is exposure to high-energy blue light.
In fact, it might be the leading risk factor after age.
Again, we’re going to have to explore a little bit of science to understand why.
In the spectrum of light, as the wavelengths get shorter, they become more energetic.
Red light has the longest wavelengths and as you move up the spectrum towards blue, the wavelengths get shorter.
Light in the blue-turquioise to blue-violet range is called “high-energy visible” or HEV light.
UV light is even more energetic.
HEV light is also referred to as “blue” light.
Some blue light is good.
Research has shown that blue light boosts alertness, helps memory and cognitive function and elevates mood.
Light therapy containing significant amounts of HEV, or blue light is used to treat seasonal affective disorder.
Blue light is also important in regulating circadian rhythm.
Exposure to blue light during the days helps maintain a healthy rhythm,
but too much blue light at night ( for example, reading on a tablet or e-reader)
can disrupt this cycle, resulting in trouble sleeping.
And blue light is everywhere.
The primary source for blue light is the sun.
The short-wavelength, high-energy part of the light spectrum scatters more easily when it strikes air and water molecules…
which is why the sky appears blue.
But the sun’s not the only source. LEDs in digital displays all emit blue light.
It might only be a small fraction, compared to the sun,
but when the amount of time we spend in front of them, and the proximity to our eyes is taken into consideration,
it’s a cause for concern.
Because the human eye is not very good at filtering out blue light.
Virtually all HEV light passes through the cornea and reaches the retina,
where blue light can cause damage to the light-sensitive cells.
When HEV wavelengths hit the retina, they set off a chemical chain reaction that can damage photoreceptors,
diminishing photoreceptor function and even causing cell death.
A number of studies have demonstrated that chronic exposure to HEV light
increases the risk of age-related macular degeneration,
and there are concerns that the additional exposure to blue light caused by digital devices poses an increased risk of AMD.
Now, the human eye is an amazing structure, and it’s evolved defenses to protect itself from blue light.
Pigments are great at filtering light,
by absorbing everything except a narrow band of the primary spectrum, which is reflected back.
For example, orange or yellow pigments reflect orange or yellow light,
while absorbing light in the complementary blue to violet spectrum.
The macula has a built-in shield called “macular pigment”
to filter out the blue light and protect the photoreceptors.
This pigment resides in a layer called the “retinal pigment epithelium,” or RPE.
The RPE contains the pigments melanin, lutein and zeaxanthin.
Melanin absorbs UV light, and lutein and zeaxanthin absorb blue light.
These pigments help catch and disperse the high energy of UV and HEV light,
significantly reducing the amount that hits the photoreceptors.
Lutein and zeaxanthin also have radical-scavenging and anti-inflammatory properties that further reduce damage.
Lutein and zeaxanthin are examples of a type of pigment called a carotenoid.
Carotenoids are yellow, orange and red organic pigments that are produced by plants and algae.
These are the pigments that give the characteristic color to pumpkins, carrots, tomatoes, flamingos and autumn leaves.
They’re only found in plants and are not produced in the human body.
They can only be obtained in the diet or by supplementation.
Modern western diets are so lacking in carotenoids
that the levels of lutein and zeaxanthin in most people’s retinas
are far below what’s considered necessary to protect vision.
The carotenoid levels in the retina can be estimated by measuring the macular pigment optical density (MPOD).
The higher the density, the higher the levels of lutein and zeaxanthin…
and the more blue light that is blocked or absorbed.
Low MPOD is a significant but modifiable risk factor for age-related macular degeneration.
Measuring MPOD is a simple, non-invasive exam that is done at the optometrist’s office.
The score ranges from 0 to 1, with average scores in the US being about 0.35.
Most eye health experts agree that a score of 0.5 or above is ideal and most protective against blue light induced visual injury.
Blue light can also cause eye strain.
Because blue light scatters more easily than other visible light, it’s not as easily focused.
When looking at a computer screen, this unfocused visual “noise” reduces contrast and can contribute to digital eye strain.
Symptoms can include eye pain, dry eyes, headache and blurred vision.
Once called computer vision syndrome,
it was recently estimated that 65% of people in the US have symptoms of digital eye strain,
and this number is on the rise.
And if you’re one of these users with digital eye strain, you’re at risk for age-related macular degeneration.
Fortunately, something can be done about it, and starting sooner, rather than later, will produce a better outcome.
First off, filter out as much high-energy light as possible.
Filters that contain synthetic melanin prevent high energy light from reaching your eyes
and are available for smartphones, tablets and computer screens.
Computer glasses designed to block blue light are available in prescription, reader and plain glass versions.
Research has shown that lenses that block light blue light increase contrast significantly and may increase comfort.
Another strategy would be to supplement.
A study was done of patients with AMD, who supplemented with a 3mg, daily tablet of melanin, zinc and selenium, called MZS.
The study showed that of the 110 eyes tested,
a clear majority had dramatically reduced pathologic macular changes.
The patients themselves reported better vision with improvements to flare, dryness, clarity and comfort.
Another study tested supplementing with lutein and zeaxanthin.
It found that those individuals who had the highest intake of dietary lutein and zeaxanthin had a 41% lower risk of developing age-related macular degeneration.
Supplementing with these two nutrients directly leads to a higher macular pigment optical density score.
One study found that taking 10mg daily of lutein and 2 mg of zeaxanthin over a period of 12 months
saw an increase in the MPOD score, from below the recommended level,
up to a healthy average range of over 0.65.
So, while the risk of developing age-related macular degeneration may be relatively low,
once the condition has progressed to the point that it can be noticed, it may already be too late.
At that point, the best that can be hoped for is to slow or halt the progression of the disease.
Why not nip it in the bud by preventing it?
Filter out as much blue light as possible with digital display filters and computer glasses designed to block blue light.
And supplement with melanin, lutein and zeaxanthin to round out a preventative strategy.
If you’re experiencing symptoms of AMD, I’d love to hear from you.
Leave me a comment and tell me what you’re doing about it.
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Thanks for watching, and I’ll catch you next week.