Adaptive Defense Part 2: Blue Light Defense Mechanisms and How They Work

In Part I of the series, we introduced the situation concerning blue light and its relationship to eye strain. In Part 2, we’ll be exploring the different lenses and enhancements designed to reduce blue light exposure, how they work, where they provide the greatest benefit, and why you would choose each. And be sure to read all the way through to receive a dispensing checklist for blue light and digital eye strain.

Understanding the Blue Light Challenge

We are continually exposed to blue light, also known as high energy visible (HEV) light, on a daily basis, both outdoors from the sun and indoors from viewing digital device screens. This blue light comprises a range of short wavelengths (380-500 nanometers) representing the highest amount of energy in the visible light spectrum. Our eyes experience great difficulty focusing on blue light, causing them to perceive it as glare, which can lead to eye strain.  

Fortunately, whether emitted by natural or artificial sources, the uncomfortable effects of blue light exposure can be alleviated by specially designed lenses and enhancements. Virtually all traditional blue light products filter most strongly in the shortest part of the blue light range (415-455 nanometers). Based on optical principles, filtering these short blue light wavelengths can alleviate the visual symptoms associated with electronic device usage. [1]

The Importance of Transmittance Graphs

It’s especially important to understand the precise blue light reduction capabilities of a lens or enhancement. The most technologically advanced lens manufacturers conduct rigorous testing of their products to measure how they attenuate blue light at numerous ranges across the spectrum. They utilize blue light transmittance graphs to show the actual percentage of filtration by the lens at different nanometers (nm).
 
Some manufacturers use a fixed percentage of filtration/reduction for their products, such as “Brand X lenses filter 80% of blue light” with no reference to a specific range of blue light. SunSync® Light-Reactive Lenses do not provide a fixed percentage because we don’t feel this is the most scientifically accurate way to discuss blue light defense. Instead, we use transmittance graphs to provide a fully transparent look at how our products defend against blue light at all points in the spectrum. 
 
For example, the transmittance graph below shows the blue light reduction of SunSync Elite XT Light-Reactive Lenses in clear and dark states. ​To read the graph, simply select a wavelength along the bottom, then reference up vertically. As you can see, in the clear state, SunSync Elite XT filters out 95% of blue light at 410 nm and 90% at 420 nm.[2]

When considering a product for blue light defense, it’s in your and your patients’ best interest to request to see that product’s transmittance graph. If the manufacturer is reluctant to provide it, ask yourself, “Why?”

​When considering a product for blue light defense, it’s in your and your patients’ best interest to request to see that product’s transmittance graph. If the manufacturer is reluctant to provide it, ask yourself, “Why?”

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​Choose Your Flavor

Several technologies are commonly used by optical manufacturers to combat the effects of blue light exposure: those that absorb, those that reflect, and those that both absorb and reflect varying wavelengths of blue light. Following are lens products and enhancements that leverage one or a combination of these to provide blue light defense:

​​Light-Reactive Lenses: Filtration
Light-reactive lenses—also known as photochromics—are an example of lenses that rely on filtration (absorption) to combat blue light. The ultra-fast variety of these versatile lenses (like SunSync Elite and SunSync Elite XT) go from dark to clear and clear to dark in seconds,[3] providing exceptional blue light filtration in both states, thus making them an ideal, always-on solution for filtering blue light.

SunSync Elite and SunSync Elite XT feature exclusive adaptive defense, which intelligently adjusts the level of filtration to the needs of the environment.

​Why choose a light-reactive lens for blue light defense?

• Exceptional defense across the entire blue light spectrum between clear and dark states.
• Adaptive defense intelligently adjusts filtration to the needs of the environment, balancing visibility, comfort, and defense.
• Versatility in all aspects of daily visual needs on top of blue light defense.
• Available on most lens designs and materials.

SunSync Elite and SunSync Elite XT go from dark to clear and clear to dark in seconds,[3] providing exceptional blue light filtration in both states, thus making them an ideal, always-on solution for filtering blue light.

Dual Defense Anti-Reflective (AR) Coatings: Absorption + Reflection
Dual defense AR Coatings like TechShield® Blue include all the benefits of a premium AR plus targeted blue light defense.

​These coatings work by both absorption and selective reflection, and generally provide the greatest defense against blue light wavelengths associated with digital eye strain in the 400-430 nm range.

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Why choose a multifunctional AR coating for blue light defense?

• Deliver targeted defense against blue light wavelengths linked to digital eye strain.
• Feature a near-clear appearance that’s more appealing to patients.
• Combine the enhanced scratch resistance, smudge resistance, cleanability, and visual performance of a premium AR coating with defense against digital eye strain.
• Available on most lens designs and materials.

Single Defense AR Coatings: Reflection Only
Single defense blue-light reducing lens coatings offer AR benefits plus blue light defense. These coatings work by reflection only, tend to focus their defense in the 400-420 nm range, and historically feature a characteristic purple appearance.

If you're leaning towards a lens coating for blue light defense, a dual defense AR would be a stronger recommendation due to its hybrid defensive properties of reflectance and filtration..

​Why choose a single defense blue light coating for blue light defense?

• Offer defense in the shortest blue light wavelengths.

Infused/En Masse Lenses:  Defense at the Core
Another blue light defense option involves the use of substrate attenuation materials infused directly into the lens to absorb blue light. Infused—or en masse—lens materials have pigments added to the lens monomer (a type of molecule used in forming polymers) to absorb blue light.

Some of these lenses feature a yellow or orange appearance, which may be undesirable for some wearers. Infused lenses generally provide their maximum defense around the 450-475 nm range.

Why choose an infused lens for blue light defense?

• Strong blue light defense in the mid to higher end of the blue light spectrum (450-475 nm).
• Longstanding history of effective blue light filtration for patients who are comfortable with the yellow or orange appearance.

​​Remember, with all the aforementioned products, it’s extremely important to view their transmittance graphs to see how they perform across the blue light spectrum and how that performance benefits your patients.

​It’s in Your Hands

 As an eye care provider, you can help improve patients’ visual comfort indoors and out by dispensing lenses and/or enhancements that reduce blue light exposure and help to alleviate the effects of eye strain. Referring to the following checklist can help you determine the best solution for each patient’s unique needs: 

• Assess your patient’s digital lifestyle Calculate the number of hours they spend looking at screens each day.
• Understand your patient’s visual behavior Do certain blue light reducing lenses or enhancements have additional benefits that accommodate a patient’s daily visual needs?
• Determine your patient’s daily environment Identify the source of their blue light exposure. Are they indoors all day, do they move between indoors and outdoors, or do they spend extended periods outdoors?
• Weigh their priorities What’s most important to them? Are they most focused on personal appearance? Do they want the best defense possible? Do they want some of both?

 
In Part 3 of our series, you’ll discover why a product that wasn’t designed exclusively as a blue light product has emerged as the can’t miss solution for patients and opticians across the country. Read Part 3 now!
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[1] “The Evolving Science of Blue Light: Technical White Paper.” Gary Morgan, O.D. VSP Optics Group. © 2017 Vision Service Plan.
[2] Blue Light Basics-Benefits of a Photochromic Lens. UUniversity Course. VSP Global.
[3] t½F of SunSync Elite in polycarbonate is 51 seconds at 73.4°.