How Much Hazardous Blue Light Comes From Led Monitor
Every day, retinal specialists are asked about the risks from blue light emitted from electronic devices. (Retinal specialists treat conditions affecting the retina, a thin tissue at the back of the eye that is responsible for vision.) Many people ask whether blue light will increase their risk of age-related macular degeneration and blindness.
The short answer to this common question is no. The amount of blue light from electronic devices, including smartphones, tablets, LCD TVs, and laptop computers, is not harmful to the retina or any other part of the eye.
What is blue light?
Blue light is visible light with a wave length between 400 and 450 nanometers (nm). As the name suggests, this type of light is perceived as blue in color. However, blue light may be present even when light is perceived as white or another color.
Blue light is of concern because it has more energy per photon of light than other colors in the visible spectrum, i.e. green or red light. Blue light, at high enough doses, is therefore more likely to cause damage when absorbed by various cells in our body.
How do we perceive color?
Our perception of color relies primarily on four main light-sensitive cells: three cone photoreceptors and one rod photoreceptor. These cells reside within the retina.
During the daytime, the three cone photoreceptors actively sense light, and each has a peak sensitivity in either the blue, green, or red portions of the visible light spectrum. On the most basic level, our sense of color is determined by the balance of activity of these three cells. When the light is too dim to stimulate the cones, our sense of color is extinguished. We perceive the world in shades of gray because only one type of photoreceptor, the rod, is maintaining our visual function.
LED technology and blue light
Most incandescent light sources, like sunlight, have a broad spectrum of light. However, light emitting diodes (LEDs) produce relatively narrow peaks of light that are crafted by the manufacturer. This allows light from LEDs to be perceived as almost indistinguishable from white light, or daylight. (They can also be made to mimic traditional artificial light sources.)
White LEDs may actually emit more blue light than traditional light sources, even though the blue light might not be perceived by the user. This blue light is unlikely to pose a physical hazard to the retina. But it may stimulate the circadian clock (your internal biological clock) more than traditional light sources, keeping you awake, disrupting sleep, or having other effects on your circadian rhythm.
The screens of modern electronic devices rely on LED technology. Typical screens have individually controlled red, green, and blue LEDs tightly packed together in a full-color device. However, it is the bright white-light LEDs, which backlight the displays in smartphones, tablets, and laptop computers, that produce the greatest amount of blue light.
Risks from blue light
It all comes down to this: consumer electronics are not harmful to the retina because of the amount of light emitted. For example, recent iPhones have a maximum brightness of around 625 candelas per square meter (cd/m2). Brighter still, many retail stores have an ambient illumination twice as great. However, these sources pale in comparison to the sun, which yields an ambient illumination more than 10 times greater!
High-intensity blue light from any source is potentially hazardous to the eye. Industry sources of blue light are purposely filtered or shielded to protect users. However, it may be harmful to look directly at many high-power consumer LEDs simply because they are very bright. These include "military grade" flashlights and other handheld lights.
Furthermore, although an LED bulb and an incandescent lamp might both be rated at the same brightness, the light energy from the LED might come from a source the size of the head of a pin compared to the significantly larger surface of the incandescent source. Looking directly at the point of the LED is dangerous for the very same reason it is unwise to look directly at the sun in the sky.
Compared to the risk from aging, smoking, cardiovascular disease, high blood pressure, and being overweight, exposure to typical levels of blue light from consumer electronics is negligible in terms of increased risk of macular degeneration or blindness. Furthermore, the current evidence does not support the use of blue light-blocking lenses to protect the health of the retina, and advertisers have even been fined for misleading claims about these types of lenses.
The bottom line
Blue light from electronic devices is not going to increase the risk of macular degeneration or harm any other part of the eye. However, the use of these devices may disrupt sleep or disturb other aspects of your health or circadian rhythm. If you are one of the large number of people who fall into this category, talk to your doctor and take steps to limit your use of devices at night, when blue light is most likely to impact your biological clock.
Can potential blue light harm be mitigated by special coatings on glasses and contact lenses?
David Evan Salk
April 30, 2019
Blue light from electronic devices, as well as higher efficiency indoor lighting and oncoming LED car headlights creates stress on our visual system, over accommodation up close, disrupts sleep cycles, and is generally not comfortable to look at. As of yet, we don't have a direct link from the use of electronic devices to macular health, BUT, given the other vision and sleep issues, it just makes good common sense to filter it. Fortunately, there are a number of products on the market that will help, including lenses with Melanin pigment which aggressively filter the target wavelengths, while providing a "Melanin Color Spectrum" -which appears very natural to the wearer. The screen apps are very ineffective at addressing the issue and distort color. Turning off devices an hour before bed is best, and using incandescent lighting to read is also a good idea. Children should be FORCED to wear eyewear that filters blue light, as there is a possible link to increased rates of myopia, from the over accommodation induced by blue light.
My mistake the guidelines were from the APA American Psychological Association. Here is a link http://www.apa.org/helpcenter/digital-guidelines
The AAP American Academy of Pediatrics has similar guidelines https://www.aap.org/en-us/about-the-aap/aap-press-room/Pages/American-Academy-of-Pediatrics-Announces-New-Recommendations-for-Childrens-Media-Use.aspx
I'm having trouble finding the AAO American Academy of Ophthalmology guidelines, but they are very similar.
Besides, Macular Degeneration is the leading cause of blindness in adults over 50. So why take a chance on the unknown.
Dr Ramsey, I would like to know your medical specialty? Having sold OCT retina scanners for the past 6 years, speaking with many retina specialist, who all seem to believe there will be a large increase in AMD in younger people by the year 2030. Do to the effects of Blue Light and that parents let very your developing eyes, with short arms hold devices for extended periods of time. As a matter of fact the recently published AOA guidelines on infants and these devices was no use before the age of 2 and less than 1 hour per day up to the age of 5.
All information on this article is theorical. Do you have any empiric prove to demostrate the harmless in the eyesight when people use electronic devices?
Arturo Roberts
April 29, 2019
Doesn't the term nanometers refer to wave length rather than frequency? Of course, there is a relationship between the two.
Yes, Arturo, nanometers is a measure of wavelength, not frequency. Hopefully the author will see these comments and correct that mistake.
Frequency in Hz is equal to the speed of light (c) in meters/sec divided by the wavelength in meters:
Frequency (Hz) = Speed of light (m/s) / Wavelength (m)
Anyone concerned about this issue (like the guys commenting) can block blue light from their computer, using a program called f.lux, or similar. This Harvard article is interesting because I have heard different. Even an article on HP's site is cautious about blue light. And they manufacture computers! It isn't even in their commercial interest to publish such articles. But thanks Harvard for providing balance. I'll continue to use f.lux as a precaution. Blue light is a relatively modern phenomena (in terms of sheer quantity). There are no long term studies. Certainly, as a minimum, block blue light before bed so as to not disrupt sleep.
Bernard Raab
April 29, 2019
Your article ends by stating that blue light has the effect of keeping you awake. Yet my Kindle device has a button which creates a "blue shade" on the screen, which is intended to promote sleep.
Which is correct?
What about these new headlights on cars and trucks that blind you
Jimmy Brown
April 22, 2019
How can anyone unequivocally say that blue light from screens has no harmful effect on the eye when there have been no long term studies on the issue? Just because a study shows that there were no harmful effects after one or two weeks doesn't mean there would be no harmful effects over years and years of exposure. Smoking one cigarette doesn't cause cancer.
Sponsor a child in need
April 20, 2019
SIR/MADAM can you please tell useing laptop will affect eyesite or not
So disrupting sleep would not have any deleterious effect on retinal "regeneration "?
Why do so many 20 year olds ( non-smokers) in the USA have drusen ( beginning macular degeneration) whereas 30 year olds not so much?
Pamela A. Mackey, JD, MLS, DRCC
April 9, 2019
(Reading Dr. Ramsey's article)
"The bottom line
Blue light from electronic devices is not going to increase the risk of macular degeneration or harm any other part of the eye. "
Thank you for this clarification and the other useful information and reminders for preserving our precious eyesight.
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Source: https://www.health.harvard.edu/blog/will-blue-light-from-electronic-devices-increase-my-risk-of-macular-degeneration-and-blindness-2019040816365#:~:text=The%20short%20answer%20to%20this,other%20part%20of%20the%20eye.
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