How Much Blue Light Are Those Lenses Really Reducing?

2/27/2019

How to know how much blue light a lens filters

You’ve likely seen (or will see) different companies claiming their lenses or enhancements reduce a specific or fixed percentage of blue light. And you’ve probably noticed that SunSync Light-Reactive Lenses do not do that.

When you hear or read that a lens product filters 90% of blue light it may sound good, but it is in fact, misleading.

The Problem with Promoting A Fixed Blue Light Reduction Percentage

Blue light is made up of a range of light from 400 – 500 nanometers (nm). Blue-light-reducing lens products do not provide one, consistent percentage of reduction across the entire spectrum. So, promoting a single percentage of blue light reduction is not the most effective way of explaining product attributes and could be considered misleading.

Blue-light-reducing products do not provide one, consistent percentage of reduction across the entire spectrum.”

Generally, these products provide the greatest amount of reduction near the 400nm mark and taper off as you progress toward 500nm. So, when you’re told that a product reduces a specific percent of blue light, what you’re not being told is that percentage is either averaged out over the entire blue light range, or that it represents the reduction (usually the greatest amount) at an unspecified wavelength.

Different blue light ranges within the spectrum are associated with different effects. For, example, blue light in the range of 400-430nm has been linked to digital eye strain.

So, if a manufacturer does not specify the amount of reduction by wavelength, they’re failing to communicate the product’s true properties and benefits. If a company tells you their product reduces 75% of blue light, your first question should be, “At what wavelength?” If a patient is complaining of digital eye strain symptoms, you’d want to recommend a lens product that provides superior reduction within that 400-430nm range.

That’s the benefit of using transmittance graphs.

If a company tells you their product reduces 75% of blue light, your first question should be, “At what wavelength?"

What Does A Blue Light Transmittance Graph Tell You?

A transmittance graph allows you to see a product’s exact amount of blue light transmittance and reduction at every point in the blue light spectrum. In other words, transmittance = transparency.

Below is the transmittance graph for a gray SunSync Drive XT lens. The white line shows you the amount of transmittance in the clear state and the gray line represents the transmittance in the dark state.

How to Read a Blue Light Transmittance Graph

To determine the amount of blue light reduction, select a wavelength along the bottom, then reference up vertically. Referring to the graph above at 400nm, SunSync Drive XT in the activated, dark state allows about 5% of blue light to be transmitted through the lens. That means it’s filtering out 95% of blue light.

As previously mentioned, the 400-430nm range is most commonly linked with digital eye strain. From reviewing the transmittance graph, you can accurately assess that SunSync Drive XT provides good defense against digital eye strain.

From the transmittance graph, you can accurately assess that SunSync Drive XT provides good defense against digital eye strain.”

Are Manufacturers Required to Display Blue Light Transmittance Graphs?

No. It’s up to the manufacturer. We share transmittance graphs for SunSync Light-Reactive Lenses because we feel it’s the most accurate and transparent way to explain what our products are doing. So, each SunSync Light-Reactive Lens is tested by an independent third-party company who provides transmittance graphs before they’re made available to the public.

We share transmittance graphs for SunSync Light-Reactive Lenses because we feel it’s the most accurate and transparent way to explain what our products are doing."

Use Transmittance Graphs to Help You Make the Most Informed Decision

Your patients come to you seeking the best products to alleviate their symptoms. With all the product claims out there, determining the best lens or enhancement choice can be complicated. Insisting on seeing a transmittance graph for the blue light products you recommend is one way you can simplify that process while providing yourself peace of mind that your patients are getting the exact benefit promised in the product claims.

Key Takeaways:

Always insist on blue light transmittance graphs for the lens products you dispense.
Blue-light-reducing products don’t deliver one, consistent amount of transmittance across the spectrum, so they can’t provide a fixed percentage of reduction.
If the lens manufacturer won’t supply you with a transmittance graph, question why.
When you review transmittance graphs, identify where on the blue light spectrum the lens’ major advantage resides.

See the transmittance graphs for each product in the SunSync Light-Reactive Lenses portfolio here.

9 Comments

Jim H Day Jr link

4/17/2019 07:07:05 am

Blue light protection is a consumer fraud, wavelength, including uv light and infrared, is never the problem, the intensity is always the cause of damage. The intensity of direct sunlight is orders of magnitude stronger. 10 trillion times!
A common device will not activate a sensor lens fr at zero distance, much less a 40cm working distance.
Protect your eyes with sun glasses and uv blocks.
No need to worry about screens, ever.

Jake link

4/30/2019 04:59:35 pm

Amen! Where's the conversation about myopia control? Spending our early years 3 feet or less from a screen is probably causing more issues for myopia progression than blue light damage.

Ed A

5/8/2019 01:44:13 pm

Blue light protection is most definitely NOT a consumer fraud. HEV has already been proven to disrupt our circadian rhythm.
The night time hours we now spend on our devices that emit HEV tell the brain its not time for bed. This un-natural stimulus is linked to sleep problems that can cause even more health problems over a period of time. Not to mention that we are under 3 feet away from the screens subjecting ourselves to low intensity HEV for most of the day. Remember, you can get a sunburn even on a cloudy day. I find your statement to be a bit misleading. Is HEV the end of the world? No. But its worth protecting yourself from.

Paul Holman link

9/27/2019 10:27:16 am

I sure appreciated the article and the comments. I've heard both sides of the coin on those who believe in Bluelight protection and those whom feel it is a unnecessary. I agree UV protection is the most critical but as also ED A stated HEV has been proven to disrupt our circadian rhythms and although we are not talking about the same "danger" as UV protection we can help reduce strain with BlueLight protection. If I had a patient on the fence over UV or bluelight hands down UV would be my recommendation but often I can offer both and it helps in addition to UV protection. I do want to tread carefully in what spectrum the bluelight protection is offering. Also my photochromic patients great news you already have bluelight protection no need to add unnecessary coatings!! I often tell my patients bluelight protection is about getting a level of extra protection in their lenses it's not about layering up unneeded options.

Paul J., SunSync Light-Rective Lenses

9/27/2019 12:31:15 pm

Hi Paul,

Thanks for your comment and for offering some insight into how you approach and discuss blue light and UV defense with your patients. Very enlightening!

Have a great day,

Paul J.
SunSync Light-Reactive Lenses

Edward H Axmacher

9/27/2019 02:44:25 pm

Thanks for the reply. I would like to point out that if you wish to provide HEV protection for your patients, photochromic aren't the way to do it. They only lock around 20%. Would you feel comfortable telling a patient a lens that only blocks 20% of the UV light is IF Blocking or protective? I sure wouldn't. The HEH blocking lens materials block upwards of 90% of HEV.

9/27/2019 03:03:18 pm

@Edward-Appreciate your input on this topic as I've learned it's always something I can learn more on for the benefit of my patients!! I agree with you 20% vs. 90% is a big difference and when I get the patient invested in blueblocking I tend to recommend Blutech lenses for best/maximum support. However if blueblocking is not the direction my patient wishes to go I'm glad to provide "some" protection in photochromic lenses. But I appreciate the importance to educate our patients on the difference in coverage of bluelight protection. Just shows us no one blanket works for everyone.

Alan B.

10/3/2019 01:24:33 pm

We’re loving the engagement and respectful exchange of opinions, but feel there are several critical considerations missing from this discussion.

1) It is vital to understand the amount of attenuation at a specific wavelength or range of wavelengths to understand the potential benefit the lens provides. Does the HEV (HEH?) blocking lens you mention block upwards of 90% of blue light at 400nm only, or across the entire blue light spectrum from 400nm to 500nm? This is a vital consideration to understand both the inherent benefit and the potential detriment of the filter.

For example, a lens that attenuates 90% blue light across the full range from 400nm – 500nm will have such a pronounced orange appearance, many patients will not be willing to adopt it for cosmetic reasons. It will also alter color perception, diminishing the wearer’s ability to distinguish, say, colors in traffic lights. Furthermore, it can adversely impact neuro-endocrine response and circadian signaling by blocking the transmittance of light from 459nm-484nm, and impede the ability of intrinsically photosensitive retinal ganglion cells to trigger suprachiasmatic nucleus response and pineal gland secretion of melatonin.

Since almost all blue-light-attenuating lens products filter on a curve, it’s vital to assess the range of attenuation, rather than using a single fixed percentage. This understanding of the percentage of light being attenuated, and the wavelength at which attenuation occurs, is exactly why we publish spectral transmittance graphs for all SunSync Light-Reactive Lenses in both clear and dark states.

Reviewing a spectral graph that shows the amount and location of attenuation is a more scientifically appropriate method to understand the amount of reduction a lens is actually providing.

2) While we would agree that intensity of blue light being emitted from screens means they present a far lesser (perhaps negligible) hazard in terms of potential to create retinal photo-toxicity, particularly compared to sunlight, prolonged exposure to blue light from screens does present the potential to induce a form of stress on the visual system that has been widely described as Digital Eye Strain.

It is factually correct to state that (a) in a plano or corrected eye, blue light wavelengths are myopically defocused by up to -1.00 and (b) only 2% of macular cone photoreceptors are “blue”, with the fovea being completely devoid of “blue” cone photoreceptors. With this understanding, we can conclude that blue light wavelengths are not well focused or processed in the human visual system, hence the reason that prolonged exposure to screens (and blue light) can lead to Digital Eye Strain.

3) The blue light attenuation provided by a light-reactive (photochromic) lens is dynamic, whereas an HEV blocking lens is static. A photochromic lens will provide attenuation in the clear state when exposed to blue light from artificial sources, and when exposed to higher intensity environmental blue light sources, the level of attenuation dynamically increases as a result of the photochromic reaction and resulting darkening of the lens. This does not happen with an HEH blocking lens.

We respect the fact that there are many different blue-light-reflecting, filtering, or blocking products on the market, all of which have some type of benefit in terms of blue light attenuation. However, we feel that a light-reactive lens, particularly an ultra-fast, light-reactive lens, provides more benefits with less downside than a static HEV blocking lens, based on an understanding of the science of blue light.

Thank you,

Alan B.
SunSync Light-Reactive Lenses

Paul Holman

10/4/2019 09:15:42 am

Thanks Alan for the great input very enlightening and I like the part of seeing light-reactive lenses vs. static HEV lenses. This is a wonderful view on Bluelight protection. Awesome Topic and I feel every time I see another message added I learn more and more about Bluelight protection and how to better present this topic to my patients.

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