What is Blue Light?
Blue light has no special meaning, it means literally: blue light. The blue sky, blue clothes, and blue pictures are all visual stimuli when blue light enters your eyes. The nature of sunlight is seven colors, so the sunlight also contains blue light.
What's wrong with Blue Light?
The essence of light is actually electromagnetic radiation. Only a small part of this electromagnetic radiation can be perceived by our visual cells, so it is called visible light, and there are many invisible electromagnetic radiations called invisible light.
Since it is electromagnetic radiation, it must have energy. The shorter the wavelength of the radiation is, the greater the energy will be. Therefore, the types of radiation on the left side of the spectrum all sound very powerful. From left to right, they are: cosmic rays , Gamma rays, X-rays, ultraviolet rays, everyone knows that ultraviolet rays can hurt the eyes and skin, and then there is the blue-violet light in the visible light.
Therefore, blue-violet light is a kind of light with relatively high energy among visible light, so compared to other colors of light, blue-violet light is indeed more likely to cause damage to the eyes.
Some animal experiments and in vitro cell experiments have also been done in the laboratory, using strong blue light to irradiate the eyes of animals or cultured human visual cells, which also confirmed that blue light does damage the light-sensitive cells in the retina.
Coincidentally, in the LED light emitted by electronic screens, blue light accounts for a relatively large proportion. It seems that the culprit of electronic screens hurting eyes is blue light!
But we have to ask a very critical question: how much blue light can cause harm?
Since natural evolution allows human eyes to see blue light, it is certainly not specifically designed to harm us.
It is wrong to throw away the dose and talk about toxicity. In fact, even if the lowest energy red light is used to irradiate the eyes with high intensity, it will damage the visual cells, but it will take several times longer than blue light.
Therefore, exposure to a certain amount of blue light is certainly no problem for us humans.
How much exposure will there be a problem? The answer is not knowing. Because this kind of thing is impossible to experiment with living people, right?
We only know that in the laboratory, using the strong light of 1500xl illuminating the visual cells, the cells will decay and die in three hours.
But what is the illuminance of the mobile phone screen? Probably between 200-300xl.
Just... not an order of magnitude!
The academia nowadays is generally accepted that although the light emitted by the LED screen is mostly blue, the overall light intensity is very low, so short-term use will not cause visible damage to the visual cells.
As for how long it takes to look at an electronic screen before it will cause damage to the visual cells, there is still a lack of sufficient research data. Anyway, it’s okay to watch for one or two hours, and it’s also okay to watch for ten or eight hours at the extreme, because the damage of blue light to the retina does not distinguish between adults and children. Many adults have been blind because of their work, facing the computer all day long.
In fact, instead of worrying about children's eyesight being damaged by blue light, we should actually worry about ourselves who are watching electronic screens all day with our eyes open, when you feel tired, remember to rest your eyes more is the most important thing
Is it enough to prevent blue light?
Some people may think that, since blue light has the risk of damaging the eyes, avoid looking at the blue light, which will definitely protect the eyes.
The problem is that we humans need blue light. The bluish-green part of blue light can improve alertness, help memory, and cognitive functions, and improve mood. It is also indispensable for children's visual development. It regulates the circadian rhythm, produces dark vision, and affects refractive development, so it is definitely impossible to completely filter out blue light.
Moreover, the child’s myopia that our parents worry about most has nothing to do with blue light damage. If the eyes are compared to an old-fashioned camera, then blue light may damage only the part of the negative film, and myopia is the problem of the lens not focusing properly. This is basically two different things, so blue light does not prevent myopia.
Most people feel that all vision problems are caused by blue light, making people mistakenly believe that they can be solved by buying a product to prevent blue light, which creates a false sense of security. It is counterproductive to let children wear anti-blue glasses to watch electronic screens for a long time.
Why is my vision blurry when I look at the electronic screen for a long time?
People who often work with computers will have this experience. After watching the computer screen for a long time, they will indeed feel tired of their eyes, and even can't see anything for a while.
This is because there is more blue light in electronic screens, and when blue light encounters small particles in the air, it will easily scatter and cause the phenomenon of "glare". (The same principle applies when the sky is blue)
A high proportion of blue light will focus in front of the retina, which requires the eyes to self-adjust and "harder" to see clearly, so we will feel tired when looking at the computer for a long time, causing visual fatigue.
In addition, sometimes we have to complete more detailed visual tasks on the computer, always need to concentrate for a long time, staring eyes carefully, we will often forget to blink, resulting in the eyes lacking water and dryness, but also cause visual fatigue.
Therefore, there may be temporary loss of vision and visual fatigue caused by long-term use of electronic screens, but this feeling is different from the permanent damage to the fundus vision cells mentioned earlier. Pay attention to rest the eyes can recover, don’t worry too much about your eyes.
What is the use of anti-blue light products?
Anti-blue light glasses have existed for a long time, but they are not intended for ordinary people. They are mainly worn by patients who have just completed cataract surgery. There are also used by those who look at the screen for a long time and engage in fine vision activities, such as e-sports players and those who design on the computer. In order to avoid visual fatigue and make the work better, they may also need to wear it.
In other cases, even the ophthalmologist will not recommend you to wear it, and it will not prevent myopia even if you wear it.
If you really need to wear it because of intense eye use in front of the screen, you should also choose the appropriate type of glasses, and only shield the so-called "harmful blue light" with a wavelength between 380-450 nanometers, and don't block out the beneficial blue light above 450nm.
Finally, to summarize, the so-called blue light is just a light with a little more energy than other colors of light. Its effect on the eyes is similar to the principle of ultraviolet rays in the sun, that is, if it is too much and too strong, it will easily burn the cells of the fundus, ultraviolet light is actually much more powerful than blue light, but the eyes of adults can better cut off ultraviolet light (but children cannot, so children should pay attention to wearing sunglasses in the sun).
The proportion of blue light in electronic products is relatively more, which is more unnatural than sunlight, which makes our eyes uncomfortable. However, because the light intensity is very low, it will not cause eye damage in a short time. In fact, even if you read and write under a well-lit LED light, you still have this fatigue problem. If the eyes feel sore or blurred, it is just a reminder of excessive eye use, rest will recover. Don't worry too much.
In fact, the most important reason for children to watch electronic screens less is to prevent children from lacking real-world play and social time, but prefer and indulge in the stimulation in the virtual world, which affects the normal development of the brain. In other words, let the child watch the screen less is to prevent him from becoming stupid. This reason is much more important than protecting eyesight!