BLUE LIGHT PROTECTION
ANOTHER BLUE perspective
Why you should be talking to patients about sunwear that filters HEV as well as UV rays
BY DEBORAH KOTOB, ABOM, NCLE
So many of our patients put their eyes at risk simply because they lack awareness of the danger that high-energy ultra violet (UV) and high-energy blue-to-violet (often called HEV or blue light) rays pose to vision.
Thanks to countless consumer education campaigns by the medical fields, the danger that UV light poses to skin health is widely understood, and precautionary actions are (hopefully) commonplace when spending time in the sun. And, thanks to the ongoing consumer campaigns by The Vision Council and other entities, the public is (again, hopefully) beginning to understand the damage that can occur to their eyes and sight when they don’t protect their eyes from the sun’s UV light.
But what about the sun’s blue light? Is it bad too?
Unfortunately the answer is yes. It figures that something we love can be bad for us.
STATS to know
87%
of respondents to a recent
survey knew that SKIN is
damaged by the sun but, only
9%
knew that sun can damage the EYE
Going BEYOND UV
I believe our current industry standard for sun lenses of UV400 protection is no longer adequate; the eyes need protection from UV and HEV light up to roughly 470nm.
Depending on the study, the ‘blue light hazard’ is from the end of the UV range to 470nm. Some suggest as high as 500, but research by Rozanowska, Boulton, et al. indicates that damage from the violet and blue portions of the electromagnetic light spectrum occurs at the peak sensitivity threshold of the blue color cone photoreceptors, which is 463nm.
The photobiology study below shows blue light damage occurs up to 463nm.
Malgorzata Rozanowska, Bartosz Rozanowski, Michale Boulton
THE GOOD/THE BAD
Blue light is what helps us wake up in the morning, as it regulates our circadian rhythms. As sunlight returns in the morning, blue light activates the wake cycle in our circadian clock; as light wanes in the evening, melatonin production is increased to make us sleep. We need some blue light. Blue light can also boost attention span, reaction time, and our mood.
Yet research is pointing to the fact that too much exposure can contribute to the development of macular degeneration, cataracts, and other ocular disorders. Newer studies indicate that it can interfere with our circadian rhythms.
In addition to what we get from the sun, the harmful effects of blue light exposure from man-made sources such as LED lighting, tablets, smartphones, and computer screens is a new area of concern, and one that is now getting a lot of attention in the form of blue light-filtering lens materials and AR coatings.
The concern with these artificial sources of blue light is that the extended amount of time we spend staring at these screens, combined with our close proximity of our eyes to the screens, may be contributing incremental blue light damage to the eye. Of special concern are the very young, who are heavy digital users and whose crystalline lenses (which absorbs some UV and HEV) have not developed fully.
Additionally, using these devices within two to three hours before sleep can interfere with our normal sleep cycle and circadian rhythm, which negatively impacts our health by interfering with normal hormone production.
HAZARDS EXPLAINED
The ‘blue light hazard’ is the potential for the retina to suffer cumulative and irreversible photo-damage from the high-energy wavelengths that comprise the violet to blue portion of the visible spectrum of light in the electromagnetic spectrum.
These wavelengths have been implicated as a contributing factor in the development of major ocular disorders, primary among them is Age-Related Macular Degeneration (AMD).
Photo-damage can occur to the fundamental building blocks of life, DNA, which result in cellular dysfunction and ultimately cell death. Photo-damage to photoreceptor cells can be irreversible. We cannot grow new photoreceptor cells. Loss of photoreceptor cells cause gaps in the information that the brain is receiving resulting in spotty areas of vision loss all the way to total vision loss.
Photobiology research indicates that photoreceptor threshold damage occurs from rays up to 440nm and retinal pigment epithelium threshold damage occurs at roughly 440nm to 470nm.
James Gallas, Ph.D., a photo-physicist and physics professor at The University of Texas in San Antonio, researched the harmful effects of sunlight on the human eye which led to the development of a synthetic form of melanin. (The melanin pigment in our retina absorbs blue light and protects the retina.) As we age we lose up to 25% of our melanin protection. Photo-damage to the eye is cumulative an irreversible so as we are accumulating damage we are also losing protection as we age.
THE AMD LINK
Researchers have been studying the link between HEV light and AMD. But because it’s a relatively new area of study, observational population studies have produced inconsistent results partially due to the difficulty in assessing a person’s lifetime of exposure.
IN or ON?
There is ongoing debate over the use of blue light-blocking intraocular implants in cataract surgery. Yet experts agree that UV- and HEV-protective sun lenses should be worn as a protective measure against photo-damage to the eye.
However, retinal photo-damage in animal studies as well as in-vivo and in-vitro photobiology and molecular studies strongly implicate photo-damage as a contributing factor in the development of AMD. There is no question that exposure to high-energy light (both UV and HEV) can result in photo-damage to the biological tissue of the eye and even our DNA.
How this damage will manifest itself and whether this manifestation will be a chronic incurable disorder, such as AMD, is being researched and debated.
TO BLOCK OR NOT TO BLOCK?
Yellow and amber filters have been developed to cover the screens of tablets and laptops to reduce blue wavelength transmission. And several spectacle lens products and coatings have been developed that block certain ranges of blue light. This is all good but ineffectual if the eye is not protected from the onslaught of blue light exposure from sunlight.
Why? Luminance is the intensity of light reflected off objects in a scene and reaching the eye. Compare illuminance from bright sunlight at 120,000 lux to tablet illuminance levels of 5 lux to 50 lux as measured using a dimesimeter by the Lighting Research Center at Rensselaer Polytechnic Institute. Interestingly, it takes 13 hours in front of a computer screen to equal a mere 15 minutes of sunlight blue lux.
So while many ECPs are beginning to understand the need to protect their patients’ eyes from blue light emanating from digital devices, they also should be talking to patients about the protecting their eyes from HEV rays while outside in the sun. A protective sun lens is only worn when outside in bright light conditions and doesn’t affect the circadian rhythm.
Deborah Kotob, ABOM, NCLE, is an ECP education facilitator with Vision-Ease Lens Worldwide.
PATIENT Education
ECPs should be talking to patients about all risks of HEV exposure, just as they do regarding UV. According to Dr. Mark Borchert, a pediatric ophthalmologist and the director of The Vision Center at the Children’s Hospital of Los Angeles, parents need to consider the following points.
• Children absorb 70% more UV light in their retina than adults. With the added lifetime exposure to HEV light from smart phones and tablets the risk of added cumulative damage is incremental. When parents know the resulting damage is cumulative and irreversible, they then make informed decisions about protecting their child’s eye health.
• Our greatest exposure is from the sun; so recommending sunglasses with both UV and HEV should be a focus for protection.
• Research has indicated that the use of sunglasses and brimmed hats for protection from sunlight can result in an 18-fold reduction in ocular UVB exposure. Recommending these simple solutions, along with sun lens and spectacle lens solutions, will help our customers preserve their sight.
Light is essential yet it has the potential to damage biological tissues that absorb it, whether in the skin, the cornea, the lens, or the retina. Advising precautionary measures is good for the patient and good for the practice.