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It’s a news story that has picked up steam in the past couple of years, especially as daily hours of “screen time” have reached near-double digits: all this reading, emailing, Tweeting, Facebook stalking, shopping and surfing is behind significant increases in cases of dry eye, visual fatigue, headaches and even ancillary issues such as strained necks and cramped wrists (back in the day, when keyboards on handheld devices prevailed, one might recall the widely-reported “Crackberry Thumb” syndrome).

All this screen time is reportedly taking a toll on our vision and on other necessary body functions, such as sleep, and “blue light” appears to be the culprit. Or is it?

A study published in the UK’s Eye journal in January, 2016 titled “Low-energy Light Bulbs, Computers, Tablets and the Blue Light Hazard,” concludes that blue light is not a health concern. The study’s lead author, John O’Hagan, head of the Laser and Optical Radiation Dosimetry Group of Public Health England in Chilton, U.K. asserted, “Even under extreme long-term viewing conditions, none of the low energy light bulbs, computers, tablets and mobile phones we assessed suggested cause for concern for public health,” said O’Hagan. (See related article, Page 71)

The “long-term viewing conditions,” however, refer to guidelines based on the “dataset of threshold data for short delay (up to 48 hours);” moreover, “there is paucity of threshold data for long term chronic exposure.” Thus, the studies’ assertions regarding what is safe “long-term” refer to a couple of days—not a couple of decades—of cumulative exposure to HEV blue light. However, someone without access to the full study (or a broader understanding of optics) who happened upon a TV news segment citing this research wouldn’t have reason to be concerned and might continue scrolling with abandon.





But what about four 60-minute computer sessions at work, topped off by five 15-minute smartphone scrolling spurts and two half-hour tablet sessions, daily, over the course of several years? Our collective habits have rapidly altered to reflect a society largely reliant on digital screens at work and also for pleasure (social media, reading entire books). This dependence has spanned age ranges, with adults incorporating digital experiences into their days in ever-increasing time spans, and children’s eyes being exposed from early toddlerhood to “interactive learning games” and other apps via their parents’ phones and tablets.

Due to the relative newness of digital devices, there aren’t any multi-year studies that conclusively establish a link between years-long exposure to high-energy blue light from these devices and the degeneration of the human retina; there simply isn’t enough available data yet. However, there are many scientific sources which strongly support this correlation, and many spectacle lens and sun lens manufacturers cite these studies as the basis for their marketing claims for blue light lenses.

VM spoke with executives from a number of manufacturers and asked them to explain the science behind their products. You’ll find their responses in separate sections throughout this article (look for the title, The Science Behind the Lens, starting on page 60) as well as their comments on the Eye study mentioned above.

Sara Bonizio is a New York-based freelance writer and a contributing editor to 20/20 magazine and Vision Monday.


THE SCIENCE BEHIND THE LENS: BluTech Lenses by BLUTECH

Greg Naes, president of BluTech and Chris Abbruzzese, vice president of marketing, noted that the company’s BluTech lens technology was developed based on “independent, high level peer-reviewed science” to address a “triple threat” of hazards throughout the blue light spectrum, which ranges from 400 to 500 nanometers. Within that range, they identified three bands that cause concern, and their potential effects: 400 to 420 nm (causes blur and glare); 400 to 440 nm (may contribute to Age-Related Macular Degeneration); and 459 to 484 nm (can suppress melatonin and cause sleeplessness).





Naes and Abbruzzese cited two research studies produced by the National Institute of Health (NIH). In one study, the researchers concluded, “Light sources that do not filter short blue visible light (400 to 440 nm) increase the risk for Age-Related Light Damage to the Retina. Additionally many drugs, supplements, nanoparticles and xenobiotics have the potential to induce the tissue to absorb light and create damage.”*

Researchers involved with the second NIH study concluded, “The circadian and neurobehavioral effects of light are primarily mediated by a retinal ganglion cell photoreceptor in the mammalian eye containing the photo pigment melanopsin. Nine action spectrum studies for these responses indicate peak sensitivities in the blue region of the visible spectrum ranging from 459 to 484 nm. Studies showed that 460-nm light is significantly stronger than 420-nm light for suppressing melatonin.”**

Abbruzzese said the BluTech lens monomer (which is not a tint or coating) was developed “to filter more of the damaging blue light known to be associated with blur, glare, macular damage and sleep cycle disruption—without distorting color perception” for the wearer. The company also conducted primary research in order to ascertain the real-world impact of their lenses, surveying 2,023 patients who wore BluTech lenses for three months or more. Here’s what they found:

• 98.2 percent of those surveyed noticed “significant sleep improvement.”
• 99.1 percent said their eyes were “more relaxed indoors.”
• 65.1 percent said they experienced “significant reduction in headaches/migraines.”
• 93.8 percent said “absolute yes to wear as everyday pair of glasses.”

To foster patient education on the topic, BluTech developed its “Beat the Blues” national campaign, which includes a “Blue Light Basics” video for eyecare practitioners with information on blue light, the science behind BluTech lenses, and how to successfully convey their vision and eye health benefits to patients.

RELATED RESEARCH
*Retinal photodamage by endogenous and xenobiotic agents. Photochem Photobiol. 2012 Nov-Dec;88(6):1320-45. doi: 10.1111/j.1751-1097.2012.01174.x. Epub 2012 July 9. US National Library of Medicine National Institutes of Health.

**Sensitivity of the human circadian system to short-wavelength (420-nm) light. J Biol Rhythms. 2008 Oct; 23(5):379-86. doi: 10.1177/0748730408323089. US National Library of Medicine National Institutes of Health.

THE SCIENCE BEHIND THE LENS: Smart Blue Filter, Crizal Prevencia by ESSILOR

There is no long-term study which conclusively proves a link between blue light exposure and macular degeneration,” observed Pete Hanlin, director, technical marketing for Essilor. “However, over the past 20 years, there have been numerous studies which suggest a correlation,” including a study which found “a correlation between Age-Related Macular Degeneration and blue light exposure for patients with diets low in antioxidants.”





Different shades of blue light interact with the eye in different ways. Joint research by the Paris Vision Institute and Essilor R&D defined “Harmful Blue-Violet Light” as being between 415-455 nanometers. “Porcine retinal cells immersed in various concentrations of A2E were exposed to very specific 10nm bands of light for 18 hours; six hours after exposure, cells exposed to the bands between 415 to 455 nm demonstrated significantly higher levels of apoptosis (non-necrotic cell death).”

Hanlin noted that not all blue light is harmful. For example, the eye’s non-visual ganglion cells are sensitive to blue-turquoise light around 480 nm, and these seem to regulate the production of melatonin, a hormone associated with the circadian rhythm. The eye’s pupil response is also centered around the 480 nm wavelength; therefore it needs to receive this light during the daytime. Thus, “products featuring Essilor’s Smart Blue Filter specifically reduce exposure to 415-455 nm (harmful blue-violet) light.”

Hanlin advises ECPs to communicate about harmful blue light along with the dangers of UV. “To keep your eyes healthy, I’m recommending lenses which reduce your exposure to UV and harmful blue light. UV light can cause cataracts to form in your eye, and harmful blue light potentially contributes to AMD. Over 9 million Americans have this condition, for which there is no cure.”

—Sara Bonizio

RELATED RESEARCH
Fletcher A.E. et. al. (2008) Sunlight exposure, antioxidants, and Age-Related Macular Degeneration. Arch. Ophthalmol. 126(10):1396-1403.

Picaud, S., Arnault, E., New discoveries and therapies in retinal phototoxicity, International Review of Ophthalmic Optics, N68, Spring 2013.



THE SCIENCE BEHIND THE LENS: Zeiss Duravision BlueProtect by Carl Zeiss Vision

David Sinnott, vice president of global product management for the Carl Zeiss Vision Care business group, stated “Zeiss does not believe there is an acute risk of retinal damage due to indoor illumination levels from any kind of standard light sources for daily use,” though he acknowledged that the Blue Light Hazard function used “to calculate standards such as the American Conference of Governmental Industrial Hygienist Threshold Limit Values and Biological Exposure Indices” was established more than 30 years ago, before evidence of cumulative retinal effects in humans caused by blue light had been reported.”





Sinnott did note evidence supporting clinicians’ concern about chronic exposure to outdoor levels of blue light illumination, citing the 1992 study conducted among 838 Chesapeake Bay watermen*, which found that “compared with age-matched controls, patients with advanced Age-Related Macular Degeneration… had significantly higher exposure to blue or visible light over the preceding 20 years.”

Regarding the oft-reported effects of higher-wavelength blue light on the human sleep cycle, Sinnott said, “Specialized retinal receptors control circadian rhythm by regulating secretion of the hormone melatonin into the bloodstream. The action spectrum for these receptors peaks at about 470 to 480 nanometers, but near-blue light up to about 520 nm contributes significantly.

“Inadequate exposure to this wavelength range during daytime hours may aggravate common health problems such as sleep disorders. For clear lenses, an AR coating that selectively reduces blue light transmission without causing unwanted visual disturbance or disruption of circadian rhythms—such as Zeiss DuraVision BlueProtect—seems a sensible choice.”

RELATED RESEARCH
*Taylor HR, West S, Munoz B, et al. The long-term effects of visible light on the eye. Archives of Ophthalmology. 1992; 110:99-104.



THE SCIENCE BEHIND THE LENS: Recharge and BluTech by HOYA VISION CARE

Asked how use of digital devices can affect sleep, Anne-Marie Lahr, OD, director of education, Hoya Vision Care, explained, “When there is an absence of blue light, our eyes sense it through the retinohypothalmic tract. Specialized cells stimulate the pineal gland to release melatonin, letting you know it’s time to sleep,” and referenced the American Medical Association policy stating “exposure to excessive blue light, including extended use of various electronic media, can disrupt sleep or exacerbate sleep disorders, especially in children and adolescents.”





Dr. Lahr noted, “when blue light reaches the retina, its high energy mixes with oxygen, creating a force that destroys photoreceptor and retinal pigment epithelium cells (RPE).” This is part of a “growing body of evidence that cumulative lifetime exposure to visible light, in particular blue wavelength light, increases the risk of Age-Related Macular Degeneration (AMD).”

Thomas Gosling, OD, cited a Kaiser Family Foundation study which found that 8 to 18 year-olds (“ages where children’s retinas are underdeveloped”) devoted an average of over 7.5 hours daily to entertainment media. On top of that, we’ve integrated other sources of blue light, such as LED light bulbs, into our living and work spaces.

Dr. Gosling said his patients’ lifestyle survey results frequently indicate increasing device usage habits, which he leverages to discuss the need to reduce blue light transmission to the eye to alleviate digital eye strain, to improve sleep and reduce potential long-term eye health risks. He also instructs his patients to turn down the contrast on their devices to halfway, reducing blue light emissions by up to 60 percent, and mentioned the new “Night Shift” setting on Apple’s iOs 9.3, which automatically shifts the display colors to the warmer end of the spectrum at sunset.

—Sara Bonizio

RELATED RESEARCH
H-135.932 Light Pollution: Adverse Health Effects of Nighttime Lighting, American Medical Association

Generation M2: Media in the Lives of 8- to 18-Year-Olds, Kaiser Family Foundation Study, January 2010



THE SCIENCE BEHIND THE LENS: Reticare Glasses and Tempered Glass Screen Protectors by RETICARE

According to Celia Sanchez-Ramos, PhD of Reticare, recent studies done by the Neuro-computation and Neuro-Robotics Group (NNG) of the Complutense University of Madrid (UCM) show that high energy light (HEV) (380-500 nm) emitted by devices powered by LEDs is substantially high.





Specifically, HEV backlit displays emitting white LEDs is almost five times higher than the light reflected from a paper or low energy light emitted from screens of older devices cathode ray tube (CRT). Similarly, ambient light powered by LED has a spectral composition with very high percentage of HEV.

“It is necessary to promote new legislation that protects workers from visual impairment in the current scenario of light with high energy that began in 2007,” said Dr. Sanchez-Ramos, a faculty member of the University Complutense of Madrid. “To do this, we must consider the results obtained by NNG, and continue to study the results of research programmed by NNG regarding visual damage done both by ambient lighting and by light from electronic devices, thus, offering an updated report to the International Commission on Non-Ionizing Radiation Protection (ICNIRP) in order to develop a new regulation, according to the data acquired for the last 10 years.

“It is essential to determine new limits for exposure to blue light (HEV) considering the vast amount of hours of exposure; increasing life expectancy; and the type of tasks performed at work, where writing/reading of texts is a priority,” said Dr. Sanchez-Ramos. “The use of electronic devices at an early age during leisure time is overly abundant and to a certain extent abusive.”

RELATED RESEARCH
Behar-Cohen F, et al. Light-emitting diodes (LED) for domestic lighting: any risks for the eye? Prog Retin Eye Res. 2011. 30: p.239-257.

Chamorro E, et al. Effects of light-emitting diode radiations on human retinal pigment epithelial cells in vitro. PhotochemPhotobiol. 2013. 89: p.468-473.

Chamorro E, et al. Photoprotectiveeffects of blue light absorbing filter against led light exposure on human retinal pigment epithelial cells in vitro. J Carcinog Mutagen. 2013. S6: 008. doi:10.4172/2157-2518. S6-008.



THE SCIENCE BEHIND THE LENS: Sharper Image TechShield by VSP OPTICS GROUP

According to Alan Burt, senior product manager, VSP Optics Group, his company “recognizes the value of current scientific and medical information on blue light, and strongly encourages continuing education for eyecare professionals through the many reliable independent sources regarding the latest research on clinical implications from blue light exposure.”





As there are currently no blue light lens products approved [to treat] disease or health-related conditions, development of the Sharper Image TechShield line is based on a body of clinical evidence* that “blue light lenses and coatings enhance visual comfort by reducing eye strain and fatigue,” and Sharper Image TechShield’s messaging supports that intended use, Burt said. The connection of the shorter wavelength range of blue light (highest energy portion) to visual strain and fatigue “is based on a widely accepted understanding of the basic optics and physiology of how light behaves and is processed in the human eye.”

Burt also noted that VSP was the first major manufacturer to provide spectral transmittance graphs to illustrate for ECPs the primary benefit that TechShield provides: reduced transmission of the shortest wavelengths of the blue light spectrum, which are associated with visual strain and fatigue.

He said VSP “welcomes serious discussion of the current science about blue light exposure, and wholeheartedly supports efforts to ensure that the product marketing claims made by manufacturers within the optical industry align with only the highest level of current scientific facts and ethical standards.”

RELATED RESEARCH
*The body of clinical evidence referenced above consists of 30 studies in total. Two are listed below. Please visit the online version of this article on VisionMonday.com for the hyperlinked complete list.

Broendsted AE, Hansen MS, Lund-Andersen H, Sander B, Kessel L. Human lens transmission of blue light: a comparison of autofluorescence-based and direct spectral transmission determination. Ophthalmic Res 2011.

25. de Fez MD, Luque MJ, Viqueira V. Enhancement of contrast sensitivity and losses of chromatic discrimination with tinted lenses. Optom Vis Sci 2002.