There is growing concern among leading optometrists and researchers over the harmful effect of blue light from LED screens on the macula and its risk of damaging the macula.
According to a recent article published in Acta Ophthalmologica a select band of blue light spectrum between 415-455nm generated the greatest risk for RPE cells, which are critical to the long-term health of the macula1.
LED lights, increasingly used in residential and commercial environments, use blue light, as do the latest high definition televisions, smartphones and computers.
Blue light is found at the upper end of the visible spectrum of electromagnetic radiation, adjacent to ultraviolet radiation, which is accepted as dangerous to the eye and to the skin.
I think everyone is in danger but in particular children…
“The way to think of it is the shorter the wavelength of the radiation, for example, x-rays and gamma rays, the more dangerous,” explained optometrist Dr. Jim Kokkinakis. “Blue light is not as dangerous as the
shorter wavelengths but nevertheless
requires our respect.”
According to recent research from Essilor, blue light is absorbed by the yellow pigments of the crystalline lens, which gradually appear as age progresses, and in the retina by pigments, rhodopsin, lipofuscin and the macular pigments (lutein, zeaxathnin,
meso-zeaxanthin)2.
Conversely, A, B and some ultraviolet rays, are filtered out by the ozone layer, then the cornea and crystaline lens.
Children at Greatest Risk
Dr. Kokkinakis believes children especially, are at particular risk of macular damage from blue light because their eyes are not as efficient at filtering out the rays.
“I think everyone is in danger but in particular children, because most children are looking at LED digital devices all day, whether it be social media, or school work or computer gaming,” he said.
“Blue light penetrates the physiological lens of a child’s eye far more efficiently than an older person. The older person’s lens filters blue light more due to the aging process which tends to make the lens go yellow, which in turn does not allow as much blue light to penetrate.”
According to Essilor, the photochemical reaction that occurs as blue light is absorbed by the crystaline lens and retina, releases toxic free radicals that slow down the retinal metabolism and cause the non-renewal and death of photoreceptors2.
Circadian Rhythms
Blue light isn’t all bad. It regulates our individual circadian rhythm and can even make people more alert. However too much
of it – if for example a person works on a brightly lit computer screen or interacts with their iPhone or iPad late at night – can recalibrate the brain so it thinks it is daytime rather than night.
Dr. Paul Gifford, a research optometrist and part-time lecturer at Queensland University
of Technology said this is where most discussion on the dangers of blue light is currently focussed. It’s also an area driving the development of new technology.
“The bigger concern with these devices seems to be the affect on regulating sleep patterns, and on the back of this a number of internet based suppliers provide blue light neutralising screens that can be put over electronic display devices, which they recommend to use before bedtime.”
Additionally, he said major spectacle lens manufacturers have developed coatings designed to protect against the potentially harmful wavelengths of blue light.
Advising Patients
“Given that there are no other side effects, and the potential affect that HEV light may have on macular degeneration, I would say patients should be made aware of these lenses in the context that although there is no definitive research supporting their use, there is sufficient evidence to state that they could help protect against development / deterioration of macular degeneration, with the only potential side effect being on sleep patterns.
“So the patient can make a decision based on this information. In this regard it is a little like myopia control, in that we don’t have a definitive answer, but there is some evidence to support intervention, and I think it is our job to keep our patients informed.
“We don’t want our patients coming back to us in 10 years asking us why we didn’t offer advice on an available product, be it a lens coating that protects against macular degeneration, or an optical device that slows development of myopia, that the course of time reveals to be of significant benefit.
“If we do provide lenses with HEV absorbing coatings, we should document that they have been advised of the potential for disturbing sleep patterns and follow up with the patient to make sure that sleep patterns aren’t disturbed.
“This is in itself a potential minefield – people could claim that they would not have crashed the car, had that accident at work, etc, were it not for their glasses that messed up their sleep patterns and made them too tired to function!,” said Mr. Gifford.
Mr. Kokkinakis also believes there is enough evidence to advise patients that it is an issue.
“I will be prescribing a blue blocking reflection free coating for at least all digital device use. It took many years to accept that we need to block dangerous ultraviolet light when outdoors, I have a feeling that unless LED lighting changes dramatically by significantly reducing blue light emittance, we will be prescribing blue blocking lenses for indoor use and changing all our computer screens to ones that protect against blue light.”
Reference:
1. Bigot, K., Barrau, C., Gondouin, P., Villette, T., Sahel, J. and Picaud, S. (2013) Blue light toxic action spectrum on A2E-loaded RPE cells in sunlight normalized conditions. Acta Ophthalmologica, 91: 0. doi: 10.1111/j.1755-3768.2013.F002.
2. Girard, Brigitte. Photosensitivity and Blue light. Points de Vue. Essilor International, 86 Spring 2013.
