Your Blue Light Questions Answered

September 22, 2020

Blue light is widely seen in current media yet many of the truthful facts remain unclear. Between proving medical claims, lens companies marketing their blue light products and other companies throwing out blue light scare tactics, there is a lot of information to sift through. I have personally done a lot of research on my own so I can educate my “engineer” customers. This article compiles a wide variety of information from several sources that can hopefully help you make sense of all of the information that’s floating around.

Eyecare providers MUST become informed of the true science of blue light, and not respond to marketing from lens companies who are providing coatings that do very little to address the problem. ALL eyecare providers should interview their patients, and recommend solutions that address their specific vision and sleep issues, whether the solution is a lens or clip-on, or avoiding the use of blue light-emitting devices at night (including the reading light itself)- we must all become experts in this topic.

-David Salk, Separating Blue Light Fact From Fiction

I read this CE a while back, Separating Science from Speculation, and it helped make sense of how and why blue light can cause eye fatigue – in terms that are easily explainable to a customer. It also explains exactly what digital eyestrain is and how blue light can affect the circadian rhythm.

How Visible Light Behaves in the Eye

In the refractively corrected eye, green light is in focus on the macula. Longer wavelength red light is mildly hyperopically defocused, by approximately +0.50D. Shorter wavelength blue light is significantly myopically defocused, by approximately -1.00D. This creates a violet-blue blur circle, or haze around the in focus green component of light. This phenomenon is known as chromatic aberration and significantly affects visual quality. Blue light diminishes visual quality in that its short, out of focus wavelengths reduce contrast. It is well known that brown sun lenses enhance contrast. This is due to the fact that brown tints limit blue light.

Digital Eye Strain

When viewing electronic devices, myopically defocused blue light results in what is now termed digital eye strain. The Vision Council defines digital eye strain as “the physical eye discomfort felt by many individuals after two or more hours in front of a digital screen”.

The symptoms of digital eye strain can be broken down into three causes: proximity of the light source (digital device) to the eye, intensity of light from the source, and frequency and duration of exposure. In considering ways to alleviate symptoms, keeping these causes in mind can guide treatment recommendations.

Circadian Rhythm

Circadian rhythm can be thought of as regulating our sleep – wake cycle. Historically, human exposure to blue light at night was relatively low. Daytime exposure to blue light, would trigger our internal clock to suppress melatonin secretion, keeping us alert and awake. As evening would fall, lack of blue light would allow for secretion of melatonin with subsequent onset of sleep. However with advancements in technology, our evening exposure to blue light is at levels never before experienced by mankind. Electronic screens on our smartphones, tablets, and computers, as well as LED and CFL light bulbs, all emit light 459-484 nm blue light affecting ipRGC function, which plays a major role in synchronizing circadian rhythms to the 24-hour light/dark cycle,

Even with all of this information put into Layman’s terms I still had questions that can all play into making a sale. I decided to ask my favorite optical nerd, because she phrases things in a way that makes sense without extra unnecessary information. If you haven’t yet been introduced to Carrie Wilson, ABOM, NCLE-AC, CPHQ, you need to be! I’ll give you the short version: you’ll learn from her and she writes books for opticians – visit her site Optigal. Here is what I asked Carrie about blue light:

For everyday use, if a consumer had only one pair of glasses, what would you recommend, and why?

Blue blocking AR is not clinically effective. To reduce blue light an appreciable amount, it must be a filter that filters out the appropriate nanometer range. This means the lens cannot be clear. Most lenses marketed as blue blocking AR actually has a yellowish tinge to the substrate that acts as a filter and the blue blocking AR is applied to the front to assist in reducing the amount of blue light that reaches the eye.This is because the tinge to the substrate is not strong enough to be effective on its own. Also, the AR is not really an AR but a modified mirror coat that reflects blue light off of the lens surface. This is why the lens has so much more reflections and more noticeably blue than other AR coatings. So with all of this in mind, if the patient needs a blue blocker for comfort or to aid in sleep health, I recommend a clear lens with regular AR and a clip with a blue filter to be worn when utilizing the computer and electronics at night. It is also beneficial for use in low light areas so that people are not as affected by the blue light headlights. This is what I did for my son.

For computer use, is one better: a blue light blocking anti-reflective coating or a blue light filter?

A filter is always better because it actually filters. Blue blocking anti-reflective coating isn’t actually an anti-reflective coating but a mirror coat that is designed to increase blue reflections off of the lens to prevent it from entering the eye. This causes additional opportunities for the patient that may be worse than the initial problem.

Is it advised to filter blue light from devices to children since their arms are shorter (more intense light transmittance) and their crystalline lenses filter less since they are clearer?

Blue light filters are more effective on children and on pseudoaphakics who have IOLs that do not filter blue light.

Material/coating/treatment white papers from manufacturers are hard to find. How do you suggest an optician obtain this info, and if they do, make sense of it at a level of knowing which product to recommend?

It is hard to get this because a lot of times the manufacturers say that it is proprietary. Not all blue light is bad. We need blue light to function properly, so manufacturers will only block certain parts of the blue light spectrum and most are under 450nm. As long as it is an actual filter, preferably with melanin based, it will be effective.

Different manufacturers give Opticians demo lenses with a laser for demonstrating the effectiveness to customers. I’ve found that one guys laser doesn’t work on the other guys lens because they are all selling different products that are marketed the same way. How do we as product sellers know how to differentiate what is best?

This is a gimmick. It’s an easy way to show how a lens blocks light at a certain nm so it is a great marketing idea but it has no scientific basis and you cannot use it as a comparison between lenses.