In discussing blue light, it is critical to separate the marketing narrative (otherwise known as B.S.) from hard science. Most of the major lens companies have over-simplified the discussion of blue light issues, and relied upon sound bites designed to excite consumers… ”damaging”, “harmful”, “dangerous”…
This strategy is misleading and undermines the value of the science that DOES show conclusively that blue light impacts our vision and our sleep cycles. Consumers who become aware of this “false narrative” will come to mistrust the optical industry, that is already under fire from many cheap online portals that promote the “why pay more” mentality…In fact, there are MANY excellent reasons to “manage” blue light, which has become pervasive in indoor applications – indoor lighting (LED), computers, tablets, smartphones, LED televisions, LED headlights, all output blue light (400-500 nm) in far greater amounts than our eyes can comfortably handle in terms of vision and sleep disorders.
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.
Toward that end, I have prepared a summary that will serve as a starting point for an intelligent, science-based discussion of blue light issues and solutions.
First of all -what is blue light?
We describe blue light as those wavelengths from 400-500 nm. However, within that range, there are different categories of blue light that 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 accurately discuss the impacts and the solutions. We also have to understand that blue light has a direct effect on our sleep/wake cycle. During the day, blue light (especially the visible longer wavelengths, helps keep us alert. At night, exposure to these SAME longer wavelengths can disrupt our sleep cycles. So, we must give importance to the time of day when thinking about and recommending solutions. Blue light, especially outdoors, can contribute to our sense of wellbeing, but also can cause damage to retinal cells, leading to 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 Ultraviolet.
The shorter wavelengths (below 430 nm) create stress on vision, specifically fluorescence of the crystalline lens, accommodation, and contrast. Fluorescence is caused by excessive blue light (electronic devices, LED lighting, oncoming headlights) which cannot be completely absorbed (melanin pigment plays an important role) before it reaches the lens. This causes glare, accommodative stress (causes us to hold things closer), and loss of contrast.
Click on image to enlarge
There is not yet evidence to support using terms such as “harmful”, “dangerous”, or “damaging” when it comes to using of electronic devices indoors, but there is reason to consider that there may be cumulative effects yet to be determined – and will take years of study. In the meantime – VISUAL DISCOMFORT & ACCOMMODATIVE STRESS are KNOWN issues. This is precisely why wearers of lenses that absorb these wavelengths experience greater visual comfort and better vision.
The other important issue to address is the KNOWN impact of longer wavelengths of blue light (460-495 nm) to our sleep cycle. There’s no doubt that a healthy sleep cycle contributes to one’s overall health, and the opposite has been PROVEN to be true in documented increased rates of obesity, blood pressure issues, diabetes, and other chronic diseases – NOT from BLUE LIGHT, but from the impact BLUE LIGHT has on our SLEEP CYCLE. There are different ways of addressing this – one solution is to not use electronic devices for an hour before bed, and use incandescent lighting (more yellow) to read before going to sleep. This will prevent the suppression of your body’s natural production of Melatonin, the hormone produced to prepare your body for a healthy sleep cycle. Another solution is to use a lens filter that will aggressively absorb the longer wavelengths of blue light that can 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 scientist who has founded sleep study clinics at both Harvard and the University of California @ Berkeley. www.sleepdiplomat.com.
As far as damage from blue light, the known culprit is the intense light from the sun, and wearing good sunglasses outdoors protects the retina. If very concerned with retinal health, wear a dark BROWN lens, which will block virtually 100% of blue light. Outdoor blue light is KNOWN to contribute to retinal cell oxidation and damage, and can lead to Age-Related Macular Degeneration.
About David Salk
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 non-prescription glasses. They are worn to manage blue light based on the time of day. We NEED the longer wavelengths of blue light to stay awake during the day, as we filter the glare causing shorter wavelengths. At night we need to reduce the glare, AND prepare ourselves for sleep, so a different filter is needed.
We even offer a lens for night driving that addresses the glare from oncoming LED lights, while allowing the longer wavelengths to pass through (to maintain alertness). It’s important that any solution for night driving that helps address glare does not adversely affect alertness.
For more information, here are some useful links where I hope you find the “blue-truth” useful:
Here’s a link to a podcast that elaborates these points, along with some links to articles (some are very detailed) that provide some “hard science”, rather than marketing lingo. PODCAST with Daniel Feldman and David Salk on Blue Light – https://www.opticaljournal.com/optical-business-news-podcast-blue-light-bull-sht/
Fluorescence of the crystalline lens – https://www.ncbi.nlm.nih.gov/pubmed/16178654
Comprehensive Study 2018 (this is a great read, but long) – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6020759/
The need for long term studies of blue light exposure (excellent) –
Effects on electronic devices on sleep –
Accommodative lag – https://www.sciencedirect.com/science/article/pii/S0042698904005887#bib44
“A 1-year follow-up reveal that compare with ordinary glasses, short-wavelength filtering lenses (blue/violet-light filters) increase the low- and medium-frequency contrast sensitivity under bright conditions and improved accommodation. They effectively relieved asthenopia without severe adverse reactions, suggesting potential for clinical application.”