In recent years, in order to save energy and reduce pollution, the incandescent lamp is gradually being phased out, replaced with energy-saving fluorescent lamps and light emitting diode light source of the utility model. But the popularity of the new type of light source also brought new problems. And the same power compared to incandescent lamps, these new light source emission spectra, a much higher proportion of blue light component. Also, people watch TV now, more and more time using the computer and mobile phone, color screen emission spectrum of blue light component proportion than sunlight and incandescent lamps is much higher. A lot of people are worried about, this situation to the human eye is unfavorable.
LED light is not "natural"
The human eye is a product of long-term evolutionary process, it adapts to the surface of the earth sun. As we all know, the sun looks slightly orange yellow. We can put the sun approximately as glowing object temperature is about 5000 degrees Celsius, it emitted from the infrared to the ultraviolet wavelength of the electromagnetic wave is not the same, including the human eye can see the visible light at different wavelengths of light by different color, according to the light wavelength from long to short sequence, we feel the colors are: red, orange, yellow, green, green, blue, purple, blue and purple are short wavelength visible light when these different wavelengths. To our eyes at the same time, we feel is white. Newton is a famous experiment that a beam of sunlight through the prism three, white light can be divided into seven spectrum.
The solar spectrum (including ultraviolet and infrared) in different wavelength (color) of the light intensity ratio is different. Near the surface of the earth, yellow green light intensity at wavelengths near 550 nm, the color of the light of the human eye is most sensitive. In the solar spectrum, from the beginning of 550 nm wavelength green light the wavelength, gradually weakened to the red direction strength longer; from 550 nm to the short wavelength of the yellow green light blue and purple light direction, intensity gradually weakens. The sun light through the earth's atmosphere, atmospheric water vapor, carbon dioxide, ozone and high oxygen light will selectively absorb certain wavelengths of ultraviolet and infrared. There is a certain amount of solar spectrum, but the human eye is not sensitive to ultraviolet and infrared. Infrared radiation to the skin, can cause the sensation of heat, so it is also called the heat radiation of ultraviolet. Too strong or too long too long will burn the skin, it will damage the eyes.
When current through the tungsten filament incandescent lamp, due to elevated temperature and hot luminous body. Its spectral distribution approximation in the light of the sun, about 40 watt incandescent lamp filament temperature about 3000 to 4000 degrees Celsius, issued light also slightly orange yellow. If by increasing the current of the tungsten wire, spectral shortwave component also increases, light emitted by the white, but blue and violet components is relatively small.
Fluorescent lamp and light emitting diode (LED) light emitting principle and incandescent completely different, their emission spectra have more blue light. In particular, led in the wavelength of 450 nm has a strong blue light, although it is believed that it is an ideal energy-saving lamps. Freeview TV and computer and mobile phone screen also have a rich blue light. The light source to emit light in the short wavelength in the blue spectral region is relatively strong, and we are used to the solar spectrum has great difference, so there are people worry that this kind of blue light strong light source to human eyes adversely.
The harm of blue light to eyes
Research shows that the blue light in the daytime to improve people's attention, improve people's mood. However, night long time exposure to blue light will give the brain to reduce the secretion of melatonin (melatonin) signal. Melatonin is a kind of biological chemical substances produced in the pineal brain, this substance is the function of regulating human biological rhythm: daytime and sleep at night. The lack of melatonin circadian rhythm will upset people, can cause insomnia and other symptoms. Long time exposure to LED light blue light component strong, or long time watching TV screen or various screen is easy to cause insomnia. Some people believe that if a long time in the blue light component strong light environment, it may affect people's mental health. But there is no definite conclusion.
The so-called blue light, usually refers to the wavelength 500~400 nm of the electromagnetic wave is, the band of the electromagnetic wave entering into the eyes, is to feel blue. In fact, the blue light of different wavelengths, the effect is not the same. Study of the light of human visual cell damage, it is not possible to direct experimental tests, but with animal as the experimental object. There are also researchers cultured in vitro treated cells to do the experiment.
Has been the mice exposed to 404 nm blue 15 minutes, the intensity of the control light, so as not to cause thermal damage, in order to study mouse retinal visual molecular chemical changes. The results showed that blue light induced retinal long-term photochemical damage, inhibition of cell metabolism, and hinder the body to provide nutrition to photoreceptors, leading to retinal degeneration. In addition, there are a group of researchers in mice experiments also found, 403 nm blue light damage in rat eyes of the photoreceptor cells, and 550 nm yellow light which do not cause damage.
Someone had rhesus monkeys exposed to high intensity blue light (441 nm wavelength) 1000 seconds (16.7 minutes). Two days later found in monkey retina damage.
Light entering the eye, absorbed by the molecules in the visual cells, induced by photochemical reaction, causing vision. At the same time light is caused by visual cell damage, especially short wavelength blue light. Found experimentally, photon energy in the visible spectrum of short waves is larger than the long wavelength photon energy, easily absorbed by some biological molecules. Molecules to absorb photons in high energy of the excited state; excited state of biological macromolecules and other molecular interactions will cause the retinal photochemical damage in the retina, middle-class life of oxygen and free radicals and lead to cell function degeneration and apoptosis. These damages are not recoverable.
The cornea of the eye, lens and vitreous body will absorb a certain amount of blue light, can protect the retina is less affected by blue light damage. However, the lens absorbs blue light, will accelerate becomes cloudy. This, in turn, will accelerate the formation of senile cataracts.
In fact, when the eyes exposed to strong light, no matter how the wavelength, will cause some eye retinal damage. Especially the short exposure to light, will cause thermal damage directly. Even if the light is not very strong, as long as the exposure time is too long, will produce harmful in photochemical reaction net membrane cells, eventually causing retinal unrecoverable damage. This is the retinal photochemical damage. So in order to protect the eyes, we should try to avoid long time work under strong light, reduce the various screen time. The proper use of protective glasses and eye protection method. Such as the use of sunglasses in strong the sun, long time to watch the screen, can be worn with a yellow, blue light absorption more goggles.
Blue light damage to the human eye how? To answer this question and present experimental evidence is not very sufficient and different views, I am afraid to have quite a long time clinical and theoretical research in order to eventually solve. Because now the blue component than the rich new light source and fluorescent screen is used more and more widespread, the effect of blue light to the human eye also caused people to pay more attention to the.
