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What Are The Most Distinct Harms of Blue Light?


The perception and vision of objects by human eye are directly related to light. In an environment with no light, it is not in question for an eye to perceive or see objects. However, light has a much more complex structure than it is thought. Each light type does not have the same effect because of its complex structure. At this point, blue light is one of the most attractive types and there are some harms in case of long-time exposure. In this article, we will give you detailed information about the harms of blue light for you.


What is Blue Light?

The light emitted from the sun contains blue, green, yellow, orange and red rays in itself. The main reason for this color differences of the mentioned rays is the difference in their respective wavelength and energy. When all these spectrum of rays come together, it provides the formation of white light which is called sunlight.

There is an inverse relationship between wavelengths, which constituent sunlight, and their energy levels. The energy of red and orange rays with high wavelength values is low, while the energy of blue-ray with low wavelength level is high. This situation is one of the main points for harming effect of blue light.

Electromagnetic rays located just outside the red end of the light spectrum are called infrared. These rays cannot be seen with bare eyes even they have the ability to heat objects. Nowadays, infrared rays are used in different fields. Blue rays, which are located on the other end of the light spectrum and have low wavelength values, are called purple rays/light as well. Beyond blue light, there are UV (ultraviolet) rays that cannot be seen with bare eyes.


Benefits and Dangers of Ultraviolet (UV) Rays

Although they cannot be seen with bare eyes, UV rays have high energy. It is known for its power to cause changes in human skin, defined as “sunburn”. Solarium machines that people use today for tanning also work with this logic. These machines contain bulbs that emit UV rays.

UV rays are extremely beneficial for human body when absorbed in the right amount. Especially, it contributes significantly to vitamin D synthesis of body. Therefore, it also provides tanning.


Although ultraviolet rays provide vitamin D synthesis and tanning, exposure to these rays for a long time may cause serious skin burn and it even triggers skin cancer. In addition, UV rays may cause eye sunburn which is also known as snow blindness and photokeratitis.

The red end of the visible light spectrum is considered as having 700 nm (nanometers) wavelength and for the blue end, this value is 380 nm (nanometers). Wavelength of blue light is between 380 nm and 500 nm. Accordingly, approximately 35% of the visible light is blue light (high energy HEV). Blue light is divided into two as blue-purple light (380-450 nm) and blue-turquoise light (450-500 nm).


Things To Be Known About Blue Light

Blue light, which has high energy and short wavelength, has a number of benefits and harms for humans. Besides these harms and benefits of blue light, other things that should be known about blue light are as follows:


Blue Light Sources Are Everywhere

The biggest source of blue light is the sun. Apart from this, it is known that many technological devices used nowadays also emit blue light. Television, computer and telephone screens, fluorescent and LED lighting can be shown as blue light source examples.[1]

The amount of blue light that is emitted by other sources compared to the sun is extremely low. However, the fact that people spend a very long time in front of these sources nowadays causes the concern about the harms of blue light. These harms are directly related to human eye.


Eye Can Not Prevent Blue Light

Eye prevents UV rays from reaching retina, which is located behind eyeball and sensitive to light. It is not wrong to say that eye has a natural filter in this case. In spite of that, it is very defenseless to blue light. Blue light passes through lens and cornea and reaches retina and causes different effects according to the amount of light.


HEV Rays Provide the Sky Appears Blue

Discussions about why the sky is blue have always drawn attention. HEV rays (blue light) are the main reason behind the blue sky. When these high-energy and short-wavelength rays hit the water and air molecules, they are dispersed much more easily than other visible rays. This causes the sky to appear blue.


Blue Light May Cause Eye Fatigue

Blue light diffuses more easily than other visible light, which negatively affects people's focus. Digital eye fatigue may occur when viewing screens emitting blue light for a long time, due to adverse effects on focus. Among the harms of blue light, digital eye fatigue can cause more serious health problems over time.


Intense Blue Light Occurs Risk of Macular Degeneration

Intense exposure to blue light may cause light-sensitive cells in our retina to be damaged. This situation significantly increases the risk of macular degeneration, resulting in permanent vision loss. It can be stated that one of the most important harmful effects of blue light is the risk of macular degeneration.

At this point, although more research is needed on how much blue light creates considerable level of risk, eye problems experienced by those who use computers and phones nowadays give an important idea. Consequently, eye doctors have some concerns that those who look at screens that emit intense blue light may experience macular degeneration at a later age.


Level of Blue Light Precautions Should Be Increased After Cataract Surgery

It is known that lens in an adult's eye blocks almost all of UV rays and prevents them from reaching retina. In addition, with aging, the ability of human eye to block shorter wavelength and high-energy blue light increases. Eye lens does this.

In cataract surgery, changing this lens will probably be considered. Intraocular lens is placed instead of original eye lens and cloudy vision is removed. However, it should not be forgotten that after this procedure, there is a probability that the eye is likely to be more defenseless against blue light. Therefore, more attention should be paid to blue light after cataract surgery. Otherwise, the harm blue light causes will show itself in a much shorter time.


Not All Blue Lights Are Bad

When blue light is mentioned, definition as "light that is harmful to eye health" can be formed in your mind. Yes, blue light has some harms, but it should not be forgotten that it has benefits as well. Blue light is emitted by the sun and when it is taken in the right amount, it provides significant benefits for human health. According to a research, blue light improves mood, increases wakefulness, and helps cognitive functions and memory.

The benefits of blue light (HEV) give effective results in different treatments nowadays. Light therapy is used to treat seasonal affective disorders (SAD) that start in autumn and usually continue until winter. Blur light is among the given ones to the patient during this light therapy.

In addition to these, it is known that blue light received during daytime is important for circadian rhythm [2]. However, it should not be forgotten that exposure to blue light in the evening and at night may have negative effects on this issue.


Glasses That Prevent Blue Light

If you look at screens that emit blue light such as phones and computers for a long time during the day, you should take some precautions against harmful effects of blue light. One of the most important measures to protect your eyes from digital screens is the glasses to prevent blue light.

These glasses, which prevent blue light, can significantly prevent blue light emitted from these mentioned screens from reaching your eyes. These glasses, which are extremely easy to use, can also be worn over contact lenses.

If you have presbyopia and use bifocal or progressive lenses, you can get the advantages of clear and wide vision of a computer screen thanks to single focal computer glasses. However, it should not be forgotten that the mentioned glasses will only be used to see objects within arm's length.

It is also known that filters with blue light blocking properties are used by glass manufacturers for glass coating. Glasses that are coated in this way seriously prevent such harmful effects of blue light.

Damages of blue light can be prevented by the methods mentioned here. However, do not forget that in addition to these, you need to consult your eye doctor to find and apply the most accurate method.

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