By David SalkIn discussing blue light, it is critical to separate marketing narratives from hard science. Most major lens companies have over-simplified the discussion of blue light issues and relied upon sound bites with provocative terms designed to excite and alarm the consumer like “damaging,” “harmful” and “dangerous”! This strategy is misleading and undermines the value of real science that conclusively shows that blue light impacts our vision and our sleep cycle.
As consumers become aware of this misleading blue light narrative, they will mistrust an optical industry that is already under fire from many cheap online portals that promote the “why pay more” mentality. The consumer perception of the optical industry is influenced by messaging from journalists who question our industries’ fairness and honesty. Our industry’s credibility is further undermined as misinformed dispensers are caught on videotape, making blatantly incorrect claims regarding blue light. All of these factors damage consumer confidence.
There are many excellent reasons to “manage” blue light from indoor applications—lighting (LED), computers, tablets, smartphones, LED televisions, LED headlights, all output blue light (400 to 500 nm) in far greater amounts than our eyes can comfortably handle in terms of vision and sleep disorders.
Eyecare providers and lens manufacturers must become informed of the real science of blue light, rather than reiterating in marketing narratives from those who sell solutions (coatings) that do relatively little to address the problem. Eyecare providers should interview their patients and recommend solutions specific to their vision and blue light-related sleep issues. The solution may be as simple as avoiding blue light-emitting devices at night (including the reading light). Rely upon scientifically based sources of information.
We describe blue light at the wavelengths from 400 to 500 nm. However, within that range, different categories of blue light have different characteristics. Shorter wavelengths affect us differently than the longer visible wavelengths (above 450 nm). So, we should not lump all blue light together if we want to discuss the impacts and the solutions accurately. We also have to understand that blue light has a direct effect on our sleep/wake cycle. During the day, blue light (especially the longer blue wavelengths, helps keep us alert. At night, exposure to these same longer wavelengths can suppress melatonin production and disrupt our sleep cycles. Give importance to the time of day when thinking about and recommending solutions. Blue light, especially outdoors, contributes to our sense of well-being, but can also cause damage to retinal cells and increase the risk of macular degeneration. We must be aware of this issue, as people are living longer and longer, and the effects of exposure are cumulative, like the exposure of our skin to utraviolet.
Shorter wavelengths (below 430 nm) create visual stress, specifically fluorescence of the crystalline lens, accommodative lag and loss of contrast. Fluorescence is caused by excessive blue light from backlit electronic devices, LED lighting and oncoming blue-rich LED headlights when driving at night, which cannot be completely absorbed (melanin pigment plays an important role) before it reaches the lens. This causes glare, accommodative stress and loss of resolution. There is not yet evidence to support using terms such as “harmful,” “dangerous” or “damaging” when it comes to using electronic devices indoors, but consider that cumulative effects have yet to be determined and will take years of study. In the meantime, visual discomfort and visual stress are known issues. This is precisely why wearers of lenses that absorb these wavelengths could experience greater visual comfort and better vision.
“A one year follow-up reveals that compared to ordinary glasses, short-wavelength filtering lenses (blue/violet-light filters) increase the low and medium-frequency contrast sensitivity under bright conditions. Furthermore, they improved accommodation, effectively relieving asthenopia without severe adverse reactions, which suggests a potential clinical application.” (www.ncbi.nlm.nih.gov/pmc/articles/PMC5554846/)
The other important issue to address is the known impact of longer wavelengths of blue light (460 to 495 nm) on our sleep cycle. There’s no doubt that a healthy sleep cycle contributes to one’s overall health. It’s important to understand that it is exposure to blue light too close to bedtime that can lead to sleep disruption, which leads to health issues. Sleep deprivation is proven to lead to increased rates of obesity, blood pressure issues, diabetes and other chronic diseases—not from blue light, but the impact blue light has on our sleep cycle.
One solution is to cease using electronic devices within an hour before bedtime. Another is to use incandescent lighting (more yellow) to read before going to sleep. This will prevent the suppression of your body’s natural production of melatonin and the hormone that prepares your body for a healthy sleep cycle. Another solution is a lens filter that will aggressively absorb the longer wavelengths of blue light that adversely affect the pineal gland’s production of melatonin.
In this regard, I highly recommend reading Dr. Matthew Walker’s excellent book, Why We Sleep. Dr. Walker is a highly respected sleep scientist who has founded sleep study clinics at both Harvard and University of California at Berkeley (sleepdiplomat.com).
Regarding damage from blue light, the known culprit is the intense light from the sun. Wearing good sunglasses outdoors provides a high level of protection for the retina. Outdoor blue light is known to contribute to retinal cell oxidation and photochemical damage, and the link to an increased risk of developing age-related macular degeneration.
As you can see, blue light exposure is both beneficial and detrimental depending on the wavelength, the intensity, the source and the time of day. For this reason, there are no “one-size-fits-all solutions,” meaning that we must be able to change the filter throughout the day to address changing light conditions and the associated visual and circadian rhythm effects. This can only be accomplished with either multiple pairs of eyewear and sunglasses or multiple clip-on blue filters.
Full disclosure: I began a project a few years ago called BlueLogic. My company offers filters for blue light that can be worn as clip-ons over prescription glasses or as nonprescription glasses. The blue light filter lenses can be worn to manage blue light based on the time of day. This will hopefully serve as a starting point for an intelligent science-based discussion of blue light issues and solutions.
Sources provided upon request.