Is blue light a “bad guy”? Don’t cut it unnecessarily.
2021.05.01
Blue light reducing glasses, blue light reducing contact lenses, and blue light reducing film
that can be attached to computer monitors.
Various products with the purpose of cutting blue light are on sale.
Therefore, many people may think that blue light is bad for the body and bad for the eyes.
However, recently, six groups such as the Japanese Ophthalmological Society and the
Japan Myopia Society jointly said, “There is no reason to recommend blue light-reducing eye
glasses to children. Rather, blue light-reduction eyeglasses may adversely affect growth.”
They have published a written opinion.
Is blue light bad for your eyes or is it necessary?
What is blue light in the first place?
Blue light is the blue area of the light spectrum that we can see (= visible light).
With a wavelength of 380 to 495 nanometers, it has the shortest wavelength and strong
energy of all visible light.
Not only the light emitted from the monitor of a personal computer or smartphone, but also
the natural sunlight contains blue light.
Is blue light bad for your eyes?
When people say that “blue light is the most energetic light in the visible light spectrum,” it
may sound like it’s bad for your eyes. In particular, you may think that the blue light emitted
from digital devices is bad.
In fact, products with a blue light-reducing function are touted as “protecting eyes from blue
light,” “reducing eye strain,” and “preventing damage to the eyeballs.”
However, according to the “Careful Opinion on Wearing Blue Light-Cut Eyeglasses for
Children” jointly announced by six organizations including the Japanese Ophthalmological
Society, the blue light emitted from the LCD screen of digital terminals is more than natural
light on cloudy days or through windows. It is said to be a level that does not damage the
retina.
In addition, the latest randomized controlled trials, which investigated whether wearing blue
light-reduction eyeglasses reduced eye strain, showed no effect.
In fact, there is currently no scientific evidence that blue light is bad for the eyes.
Harmful effects of “blue light reduction”
Rather, it seems that there are disadvantages to cutting the blue light.
Especially for children, sunlight is necessary for physical and mental development.
It is known that children are at increased risk of developing myopia if they are not exposed to
sufficient sunlight, and in the opinion, “wearing blue light-cut glasses may be more harmful
than the exposure to blue light itself.” “I can’t deny it,” he said, emphasizing that “there is no
reason to recommend that children wear blue light-reducing eyeglasses.”
Blue light reduction is not recommended during the day
However, the only adverse health effect of blue light is the relationship with the body clock.
We are said to set the body clock by light. And it is the blue component in the light that
distinguishes day and night to us.
The sun’s rays are brightest in the daytime, and only red light reaches the surface of the
earth at sunset.
Therefore, exposure to strong light or blue light from a digital device until late at night is
contrary to the natural rhythm, and can upset the internal rhythm and cause sleep disorders.
Therefore, it is recommended that you refrain from using digital devices for a few hours
before going to bed, or use them in dark mode or night mode.
On the other hand, during the day, there is not sufficient reason to reduce blue light.
For those who tend to get tired from working on a computer for a long time, it is more
important to take a conscious break than to reduce the blue light. The American Academy of
Ophthalmology advises that the best way to relieve eye strain is to “take frequent breaks and
take your eyes off the screen.”
◎ Reference
Japanese Ophthalmological Society, Japanese Ophthalmologists Association, Japan Myopia
Society, Japanese Association for Strabismus Vision, Japanese Association of Pediatric
Ophthalmology, Japanese Association of Certified Orthologists “Careful Opinion on Wearing
Blue Light Cut Eyeglasses for Children”
https://www.gankaikai.or.jp/info/20210414_bluelight.pdf