Screening out the Blue
Why high energy visible light—also known as blue light—is posing a new threat to eye health, and how ECPs can protect their patients with specialty lenses and coatings
By Susan Tarrant
Within the past year, blue light has become a buzz word in optical. Special blue light filtering lenses and coatings for indoor lenses have begun popping up on our product landscape. Why? It certainly isn’t because blue light is new…or that researchers just discovered it’s bad for us.
It’s because we are exposed to it more than ever before. And, according to experts in the field, it’s going to take a toll on vision health if we don’t start protecting patients now.
WHAT AND WHERE
Consider the spectrum of light (see illustration). Visible light is the light between around the 380nm and 800nm wavelengths. Blue light (also known as high energy visible light or short wavelength visible light) is commonly considered to consist of the spectral wavelengths between just under 400nm to 500nm.
Visible Light Spectrum
The visible spectrum of light. The harmful HEV light lies at the lower end, between 400nm and 500nm
As was noted in a roundtable discussion and resulting white paper sponsored by Essilor, “short wavelength light plays a paradoxical role in health and vision.” On one hand, it plays an essential role in color vision. On the other hand, it is vital in triggering physiological responses such as circadian rhythm synchronization. Also, prolonged exposure to it can cause serious damage to the inner eye, including macular degeneration and, eventually, blindness.
The blue light that causes visual distortion is in the 400nm to 460nm range. The wavelengths most damaging to macula are at about 460nm. And the wavelengths causing circadian rhythm disruption are between 460nm to 490nm, with a peak at 484nm. Let’s break down each.
BLUE LIGHT AND VISION
Blue light has two main effects on vision: because the blue spectral range is a scattered light, it causes chromatic aberration; and it can kill photoreceptor cells, leading to macular degeneration.
■ Clarity. Though individual scientists may quote slightly differing numbers, it is generally accepted that the shorter the wavelength between 400nm and 500nm, the greater the degradation of vision. Products that filter any part of these wavelengths are going to provide crisper vision.
■ AMD. There is a growing body of evidence that exposure to blue light, over time, increases one’s risk to developing AMD. According to one study, “deep blue light has been described as 50 to 80 times more efficient (damaging) at causing photoreceptor death than green light.” While the cornea and lens will absorb the UV wavelengths (causing its own problems in those areas), visible light enters the eye and goes directly to the retina, with its shortest wavelengths—blue light—contributing to AMD.
|WHY YELLOW ISN’T GOOD ENOUGH|
It’s true that any kind of yellow tint will block blue light waves. Because blue light waves are the most scattered, blocking them can lead to crisper vision. So why not just put patients in a yellow tinted lens and be done with it? Because it can be dangerous.
For everyday vision, a simple yellow tint is NOT the answer. Here’s why:
COLOR DISTORTION. To simply block the entire blue light area of spectrum causes color distortion. That’s an acceptable trade-off for activity-specific eyewear such as for shooting and some outdoor sports where crispest vision is the ultimate goal. But otherwise, a simple yellow tint will cause color distortion and can result in problems like not seeing the correct colors in traffic lights, etc.
NIGHT VISION. During the day (photopic vision), all the photoreceptors in the eye contribute to a combined sensitivity to color that peaks in the yellow-green region of the spectrum around 555nm.
At night (scotopic vision) the eye’s peak sensitivity drifts from 555nm to closer to around 420nm. It’s called the Purkinje shift. The eye’s peak sensitivity is now right in the middle of the blue end of the spectrum. So wearing yellow tinted lenses at night would block the transmission of the very wavelengths that we see best.
The best solution is lenses or coatings that filter the blue light, not block it completely.
BLUE LIGHT AND SLEEP
Aside from affecting vision and eye health, our increased exposure to blue light through artificial sources is affecting our circadian rhythm. A plethora of studies have been published implicating the use of LED devices and the disruption of our bodies’ natural sleep/wake cycle.
Digital products we use every day emit blue light. Image courtesy of PFO Global
The basic science is this: our bodies secrete melatonin, our “sleep” hormone. Blue light suppresses the secretion of melatonin. Ideally, our day exposure to natural light (and the blue light therein) suppresses the melatonin, storing it for release later at night (when the natural/blue light isn’t present anymore) when we need to sleep.
It’s not a “new” issue. But our reliance on computers, smartphones, and iPads and subsequent exposure to blue light through LED screens pushes the issue to the forefront. Children and adults are sitting in front of their devices right up until bedtime, with blue light suppressing their production of melatonin.
“Then people wonder why they’re tossing and turning and can’t get to sleep,” says Gary Morgan, OD, of EyeTech Eye Associates, Peoria, AZ.
Screening and Greening
If blue light exists in natural light, why is this suddenly a big issue now? Because “greening” efforts have changed incandescent light bulbs to fluorescent and compact fluorescent lights (CFL), which emit much more blue light. The same is true for LED screens (which include most back-lit screens). It’s the latter source that is causing the most concern.
There may be only five or 10 percent transmittance of blue light coming off the screens, “it’s just that we are so close to them, and we are projecting it directly into the eye. It is virtually right there,” says Thomas Gosling, OD, of Optical Matters in Littleton, CO. Though CFL bulbs transmit a large amount of HEV, we don’t stare directly at the bulbs. Furthermore, children lack any ocular lens pigment, which comes with age and helps filter the dangerous light.
“Our children have very large pupils, very pristine and clear lenses, and they have short arms. So they are holding these devices closer to their eyes,” says Gosling. “They’re the ones at great risk for retinal damage, and that’s where we need to be more aware.”
It’s not just the proximity of these devices to our eyes that is cause for concern, it is the sheer number of hours children and adults spend in front of them.
|FOR FURTHER STUDY|
There has been plenty of recent research done into the dangers of blue light. Some of it is manufacturer-sponsored and some of it independent peer-reviewed. Here are just a few of those studies (many of them used as sources for this article). Read them and make your own decision about which products you want to prescribe.
“The Macular Degeneration Epidemic: Beyond UV Protection,” by Gary Morgan, OD
“Blue Light Hazard: New Knowledge, New Approaches to Maintaining Ocular Health,” report of a roundtable in March 2013 sponsored by Essilor International
“Considerations in the Prescription and Use of Photoprotective Eyewear,” by Gary Heiting, OD, sponsored by Vision-Ease Lens
“Blue Light Has a Dark Side,” Harvard Health Letter, May 2012
“Age-related Maculopathy and the Impact of Blue Light Hazard,” ncbi.nlm.nih.gov/pubmed/16445433
“Visible Light and Risk of Age-related Macular Degeneration,” ncbi.nlm.nih.gov/pubmed/2095019
“Sunlight and the 10-year Incidence of Age-related Maculopathy: the Beaver Dam Eye Study,” ncbi.nlm.nih.gov/pubmed/15136324
“High Sensitivity of the Human Circadian Melatonin Rhythm to Resetting by Short Wavelength Light,” ncbi.nlm.nih.gov/pubmed/12970330
“I think it’s absolutely something we should be talking about more,” says Anne-Marie Lahr, OD. Lahr is currently director of education for Hoya Vision Care, and prior to that was assistant professor and course coordinator of Optical Principles and Ophthalmic Applications at Pennsylvania College of Optometry. “It’s detrimental to vision, people don’t know enough about it, and it really can lead to blindness.”
Picking Your Product
To protect patients, ECPs now have a few excellent choices:
■ Blue filtering lens. This has the filtering agent in the lens material itself, and is infused with ocular lens pigment and melanin to filter the light across the 400nm to 500nm spectrum without altering color perception.
■ Blue filtering coating. Several AR coatings are now available that combine the benefits of AR with an attenuation of harmful blue light rays, while still providing crisp vision and good color transmission.
Here are some other tips for springboarding blue light protection into business applications:
■ Plano Displays. Though not every kid needs corrective eyewear, almost every kid (and most adults) spends substantial time in front of digital screens. A display case with plano blue-light filtering lenses already mounted into frames can be a great revenue center, and capture patients who don’t need eyewear, or who wear contact lenses.
■ Word of mouth. When you talk to your patients about AMD and blue light, they’ll talk to their friends about it; and about you. People will start to seek you out, especially if they’ve got a family history of macular degeneration.
BluTech lenses: HEV filtering built into a 1.56 high-impact lens (clear and sun) via ocular lens pigment and melanin blutechlenses.com
All of the Unity PAL , single vision, and computer lens portfolio is available in BluTech lenses vspoptics.com
BluTech lenses available in Kodak Unique and Precise progressive lines, SV, and FT-28s signetarmorlite.com
ESSILOR OF AMERICA
Crizal Prevencia, a No- Glare coating filtering blue light waves crizal.com
HOYA VISION CARE
Recharge, and AR coating that also filters harmful blue light waves thehoyafreeformcompany.com
iBlu Coat, available on Resolution polycarbonate lenses, filters HEV light optimainc.us
See Blue Coat, blue light filtering coating available on all Nikon lenses nikonlenswear.us
Cocoons’ low vision fitover line blocks up to 100 percent of blue light liveeywear.com
Coppertone Lenses (sun) blocks the harmful HEV vision-ease.com
Nu-Polar lenses filter shortwave blue light, but retain color perception youngeroptics.com
Happy Lens (un)block short wave blue light, but let in more of the long wave light that regulates circadian rhythm Spyoptics.com
*Note: This list is not all-inclusive. Other indoor lenses, by virtue of their material or treatment, may offer a degree of blue light filtration. The same is true of sunwear. This list is meant to include products created to attenuate specific regions of the blue light waves.
Let your local news know that you are available as a resource for information about this topic, which is only growing in popularity. Businesses can be built on referrals.
■ Beyond Recommending. Don’t stop at simply recommending some lens options. Prescribe the product. It is not selling as much as it is serving your patients.
“Whether you give [patients] a filtering coating or a filtering lens, the opportunity is there to provide patients with a product that will protect their eyes,” says Lahr.
And that, in turn, is going to increase revenue.
John Rumpakis, OD, MBA, president and CEO of Practice Resource Management, Inc., says ODs need to understand what’s going in their patients’ lives as it pertains to vision, and not shy away from actually prescribing product.
“We don’t think preventatively enough in optometry,” says Rimpakis, adding that prescribing product as a proactive measure is a new way of thinking for many in the industry.
“This is a paradigm shift, but a necessary one. Profit should always be secondary,” he says. “It’s nothing more than a by-product of recommending the standard of care.” EB