Intense discussion over the pros and cons of blue light has intensified over recent years and inspired the introduction of lenses to block out the negative impact of these higher energy rays. But how important is it to go recommend blue-light blocking lenses – is this a fad or a fixture that will slowly change the eye health of generations to come?
Blue light can be great for health, or it can have serious effects on the human eye – depending on whether its radiation is classed as good blue light or bad blue light.
It was the naturalist photographer, John Ott who uncovered the health effects of sunlight and artificial light. He advocated that sunlight is an essential nutrient to a healthy life and artificial light, produced by conventional bulbs and fluorescent tubes, is not healthy. He also showed that artificial light could be converted to full spectrum to simulate sunlight for indoor use.
Such was Ott’s expertise in this area that he was engaged by Walt Disney to film the time-lapse plant growth sequences for many nature films as well as the famous pumpkin-to-coach scene in the movie Cinderella.
..the production of melatonin/seratonin when light enters the eyes found that blue light can affect sleep patterns set by our body’s natural circadian rhythms
Ott went on to research the effects of natural sunlight on the learning and behavior of children, the increased generation of Vitamin D, and the production of melatonin/seratonin when light enters the eyes. He identified “Seasonal Affective Disorder” or SAD, a syndrome associated with light deprivation.1
Malatonin Production
Further research into the production of melatonin/seratonin when light enters the eyes found that blue light can affect sleep patterns set by our body’s natural circadian rhythms.
While light of any kind can suppress the secretion of melatonin, according to a study conducted by Harvard researchers, blue light does so more powerfully. In an experiment comparing the effects of 6.5 hours of exposure to blue light with exposure to green light of comparable brightness, the researchers discovered that blue light suppressed melatonin for about twice as long as the green light and shifted circadian rhythms by twice as much (3 hours vs. 1.5 hours).
Researchers at the University of Toronto compared melatonin levels in a group of people wearing blue-light-blocking goggles when exposed to bright indoor light with a group exposed to regular dim light and wearing no goggles.
They found melatonin levels were about the same in the two groups, further strengthening the theory that blue light is a potent suppressor of melatonin. The research “also suggests that shift workers and night owls could perhaps protect themselves if they wore eyewear that blocks blue light”.2
What about Eye Health?
The effects of light toxicity in relation to the eye are well known. UV has more of an impact on the cornea and the crystalline lens, while visible light and near infrared radiation has more of an impact on the retina.
UV light is generally defined as that part of the invisible spectrum that ranges from 380nanometer (nm) to 200nm. The wavelengths of blue light are near to UV in the 500 to 381nm range, and it is these higher energy rays that have nabbed the attention of many of the world’s biggest lens laboratories.
A four-year research programme conducted by Essilor in partnership with Paris Vision Institute, one of Europe’s largest eye health integrated research centres explored the effect of light on the retina.
In order to identify the part of the spectrum that is damaging to the human retina, the team developed a completely new protocol: an in vitro test on retinal cells with narrow screening light exposure to determine the harmfulness of rays depending on their wavelength. This test, which was a scientific first in ophthalmic optics, resulted in the discovery that wavelengths between 415 and 455 nm (spectral band centered at 435 nm +/- 20nm) are the most harmful for the target retinal cells.
From the day we are born, our eyes are subjected to these harmful blue-violet rays that make up the spectrum of natural light. Increasingly too, we subject our eyes to artificial blue light emitted from solid state lighting (SSL) and light emitting diodes (LEDs), which are rapidly replacing the old incandescent and compact fluorescent lamps.
The level of exposure is only going to increase. Leaders in the lighting industry predict that by 2020, 90 per cent of the world’s lighting sources will be based on SSLs and LEDs.3 And because LEDs are so compact, not only are they being used for domestic and commercial lighting. They’re becoming more common in children’s toys and even clothing… not to mention televisions, computers, tablets and smartphones.
Very few people are able to avoid the use of screen base technology. Whether at work, school, home or even out socially, screens are all around us. And they all emit blue light.
According to Christophe Martinsons, Head of Lighting and Electromagnetism at CSTB Grenoble France, although LEDs emit negligible UV and infrared radiation, they are linked to visible light and “more particularly the blue part of the spectrum”.
Mr. Martinsons stated that blue light could be harmful to the retina as a result of oxidative stress. He said in general the photochemical damage of the retina depends on the accumulated dose to which the person has been exposed, which can be the result of a high intensity short exposure but can also appear after low intensity exposure repeated over long periods.3
Essilor’s research identified that exposure to UV light can be a factor in the development of cataract and exposure to blue light can be a factor in early onset of age-related macular degeneration. This is not a new finding.
In studies that exposed rhesus monkeys to high intensity blue light at 441nm for duration of 1000 seconds, Dr. William Ham, who has been described as an expert on the effects of radiant energy on the retina,4 noted that two days after the exposure, lesions had formed in the monkeys’ retinal pigment epithelium. Dr. Ham concluded “long term, chronic exposure to short wavelength light is a strong contributing factor to age related macular degeneration.5
In 1983 he wrote: “Most authorities now believe that the near UV radiation absorbed throughout life by the lens is a contributing factor to ageing and senile cataract. Thus, by protecting the retina from near UV radiation, the lens may become cataractous. My own personal opinion is that both the retina and the lens should be protected throughout life from both blue light and near UV radiation. This would delay the onset of senescence in both the lens and retina (senile cataract and senile macular degeneration).”
In 1998, Nancy Quinn, a US based Registered Nurse and ‘expert’ in blue light stated, “there is mounting medical evidence that prolonged exposure to blue light may permanently damage the eyes, contribute to the formation of cataracts and to the destruction of cells in the center of the retina.”5
Eye care professionals in Australia have also expressed their concern over the harmful effects of blue light. Behavioural optometrist Helen Summers, is particularly concerned about the need to protect children’s eye health.
“In our schools, our children have increasing use of tablets, computers and other devices for educational use, social media, and gaming – and from an increasingly younger age. With the growing use of digital screens, not only is there an increasing visual demand, and asthenopia symptoms, but also increasing exposure to blue light,” Ms. Summers commented to mivision.
“It is a concern that our children are possibly more vulnerable to blue light exposure and their accumulative effects because their immature crystalline lenses are not able to block blue light,” said Ms. Summers.
According to Essilor, during childhood, the eye is very transparent and lets all visible light and some UV pass through to the retina. After the age of 45, the eye’s natural defence system is weakened. By 2050 there will be 3.7 billion people aged over 45.3
Ms. Summers said while there is a need to embrace technology, it is just as important to minimise the adverse effects of technology use.
“In our practice, we see an increasing number of students with symptoms of near stress and erratic school performance. We question every student on the type and hours spent on electronic devices per day, for educational and social use.
“We advise on visual hygiene, discuss effects of cortisol and circadian rhythms, give them lens support when required, and now can also offer protection from the effects of accumulation of blue with specific AR coatings,” added Ms. Summers.
Protective lenses
In recognition of the growing concern about the harmful effects of blue light, many of the international lens laboratories have already introduced blue light blocking lenses. In February 2013, Essilor launched what it claimed to be the “first preventive lenses” that offer selective protection against harmful blue light that can contribute to AMD and against UV rays which can contribute to cataracts.
The Crizal Prevencia lens can protect the eye from wavelengths that contribute to the degeneration of retinal cells while allowing beneficial blue light to pass through. All this while maintaining the transparency
of the lens.
According to Hoya’s Product Manager Jessy Fong, Hoya has worked hard to find a solution that can prevent the negative effects of over-exposure to blue light. Together with its scientific partners, Hoya has developed “BlueControl multi-coat”, an anti-reflection coating that Ms. Fong says will neutralise blue light emitted by digital screens, prevent eye fatigue, eye strain and sleeplessness.
Rodenstock’s range of lenses with specialty tints have been available for many years. There are the ‘medical filters’ and the ‘sun contrast’ range of tints that are designed to filter out specific wavelengths of light. In terms of blue/violet light filtering, the L400 tint offers a very light brown tint with the specific wavelengths of approx 456nm reduced to approximately 82 per cent transmission. He said these lenses are recommended for the correction of Aphakia and during photo chemotherapy.
“The great thing with the L400 tint is that it is available on all products in 1.5 and 1.6 index and comes with the most cosmetically appealing Solitaire Protect Plus multicoat,” said Mr. Hentschel.
Although Carl Zeiss doesn’t currently have an AR coating designed to minimise the exposure of blue light transmittance, the company is working on it.
“Our vision scientists are investigating how blue light may impact visual performance and ocular health in order to determine the most viable lens options for enhancing patient care,” said Andrew Lin, who is a Product Manager at Carl Zeiss.
In the meantime, he said the Zeiss PhotoFusion brown photochromic lenses with AR coating is suitable for patients at risk of over exposure to blue light.
“PhotoFusion brown lenses with an AR coating provide blue light transmittance indoors comparable to recently introduced lenses with “blue-blocking” AR coatings. However, PhotoFusion lenses provide substantially greater protection outdoors, where protection from harmful blue light is more critical,” he said.
CR Surfacing, Australia’s longest running independent lens laboratory has launched into 2014 with the introduction of its own UV blocking lens which filters blue light. There’s no doubt there will be more to follow.
Further Blue Light Protection |
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Increasingly evidence is suggesting that eye care professionals should recommend lenses with a blue light filter to patients who are highly exposed to the blue light rays from artificial and natural light sources. Additionally, there are other practical and lifestyle oriented steps that can be taken to protect your patient’s vision over the long term:
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Low Blue Light Screen Technology |
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While lens manufacturers are working on ways to filter blue light as it hits the eyes, already there are commercial moves to stop electronic blue light at the source. BenQ, a leading manufacturer of monitors for television and computers, is one of the first to develop a range of computer monitors with low blue light features. Most monitors – particularly those in mobile devices – are LED (light emitting diode). The alternative, older technology is CCFL (cold cathode fluorescent lamp), which is far less power efficient. A blue-light briefing paper from BenQ indicates its research has noted a “significant difference in blue light emission” between LED and CCFL. Rather than using a coating to reduce blue light, BenQ says its proprietary colour adjustment technology delivers reduced blue light while maintaining good colour reproduction. BenQ says it began phasing in eye care technology for all new computer monitors in August last year. “The benefit of low blue light technology is to reduce the blue light hazard for prolonged usage of computer display. Blue light is a part of nature and required for displaying colour correctly. Hence, reducing blue light will invariably affect colour accuracy to some extent, but the impact will be minimal to non-colour “BenQ’s low blue light-enabled monitors have been preset with four viewing modes which adjust light levels and contrast to suit reading, multimedia use, office work and surfing the internet.” BenQ said low blue light technology would benefit all monitor users, however it points out that the technology is incompatible with 3D. “Nowadays people use electronic devices all day long. According to medical studies, prolonged use of monitors without low blue light technology will result in macular degeneration. Hence, we encourage everyone to choose a low blue light technology-enabled monitor to reduce the risk.” |
References
1. www.cancercontrolsociety.com/bio2000/ott.html
2. www.health.harvard.edu/newsletters/Harvard_Health_Letter/2012/May/blue-light-has-a-dark-side/
3. Points de vue, International Review of Ophthalmic Optics, Essilor Issue 68
4. http://ead.lib.virginia.edu/vivaxtf/view?docId=vcu-tm/vircuh00039.xml
5. www.cclvi/org/contributions/effects1.htm
