Blue light: risk to your eyesight or unnecessarily overestimated phenomenon?

The composition and effects of light on the body are a much more complex problem than it may seem. Go for a walk during a sunny afternoon, light tube, computer screen, mobile phone, or other digital devices - activities that lead to the exposure of your eyes to visible (and sometimes invisible) radiation that can have many effects on you and your health.

Most of the population is likely to know the distribution of sunlight into the visible and invisible part. Invisible ultraviolet radiation can cause get brown or even burn your skin, and infrared causes a pleasant feeling of warmth. However, many have no idea that visible light emitted by the sun involves several different rays of light that contain varying amounts of energy.

What does "blue light" mean?

Sunlight consists of rays of red, orange, yellow, green and blue and a variety of their nuances, depending on the energy and wavelength of the individual beams. Together, the whole spectrum of light rays creates what we call "white light" or sunshine.

There is no need to get into complex physical theory, but we must mention that there is an inverse relationship between the wavelength of the light rays and the amount of energy they contain. Light beams that have relatively long wavelengths hold less energy and vice versa.

The rays at the red end of the visible light spectrum have longer wavelengths and therefore less energy. In contrast, the beams at the blue end of the spectrum have more energy.

Invisible radiation with wavelengths longer than red light is called infrared radiation.

On the other hand, radiation with shorter wavelengths (and higher energy) than blue light is called ultra-violet (UV) and can cause an unpleasant get red of our skin after sunbathing. However, UV radiation has beneficial effects to a limited extent as it helps the body to produce vitamin D.

Figure 1 - Colour spectrum of visible light with wavelengths; Source: chm.davidson.edu

Visible light is generally considered to be a spectrum of radiation with wavelengths ranging from 380 nanometres at the blue end of the spectrum to about 700 nanometres at the red end.

The blue portion of the light is then usually defined as visible light with a maximum length of 500 nanometres - approximately one-third of all visible light with the highest energy.

Key characteristics of blue light

Like ultraviolet radiation, visible blue light has both advantages and disadvantages. What is the essential information you should know about the blue light?

1. Blue light is everywhere

Sunlight is the primary source of blue light. If you move outdoors during the day, you are exposed to it almost always. However, there are also many artificial blue light sources, including fluorescent tubes and LED lighting or smart TV.

We are exposed continuously to the blue light emitted by the display of computers, notebooks, smartphones and other digital devices that emit significant amounts of light.

The amounts of blue light emitted by these devices are only a fraction of the light emitted by the sun. However, the time people spend using these devices and the closeness of the screens to their faces is a concern for the eye doctor. We do not know precisely the long-term effects of blue light on human eyes.

2. Blue light = blue sky

Short-wave high-energy light rays at the blue end of the visible spectrum spread more quickly than other rays after colliding with water molecules in the atmosphere. Higher scattering of these rays thus makes the cloudless sky blue.

3. The eye is not very effective at blocking blue light

The cornea and pupils of the human eye are very useful in blocking UV radiation. Less than one per cent of this radiation is released to the light-sensitive retina on the back of the eyeball (however, even this amount of UV radiation can cause irreversible changes). However, keep in mind UV-blocking sunglasses protect the cornea and pupil, as well as other parts of the eye from damage. In extreme cases, damage caused by UV radiation can also lead to cataracts or snow blindness.

Unlike UV radiation, however, almost the entire blue spectrum of visible light passes through the cornea and pupil and reaches the retina.


Figure 2 - Cross section of the human eye; source: wikipedia.org

4. Exposure to blue light may increase the risk of macular degeneration

The fact that blue light penetrates the retina is very crucial. Laboratory studies show that significant exposure to blue light can damage light-sensitive cells found in the retina.

These consequences are like changes in macular degeneration - loss of central vision - which can lead to permanent loss of sight.

More research is needed to determine how much natural and artificial blue light is "too blue light" for the retina. Yet, many eye care providers are worried that the added exposure of blue light from computer and smartphone displays may increase the risk formation of macular degeneration in later life.

5. Blue light puts more anxiety on your eyes

Because blue light is more easily scattered, it is more difficult for the eye to focus. When you look at computer screens and other digital devices emitting significant amounts of blue light, this "blurred visual noise" reduces contrast and can contribute to excessive eye strain.

Lenses that block blue light significantly increase contrast, lenses with yellow tones can substantially enhance your comfort when looking at digital devices long-term.

6. Not all blue light implies harm

If blue light brings several adverse effects on the human body, why not just protect our eyes entirely from it?

It would not be the best idea. It is relatively well documented that specific exposure to blue light is essential for human health. Blue light increases alertness, promotes good memory, cognitive functions or improves mood.

That is why light therapy is used to treat the seasonal affective disorder (so-called winter depression) - a type of depression whose onset is associated with seasonal changes, with symptoms usually beginning to appear in autumn and continue during winter. The light sources used for this therapy emit a bright white light that contains a significant amount of blue light rays.

Blue light is also crucial for regulating the circadian cycle - the natural alternation of the state of alertness and sleep of the human body. Exposure to blue light during daylight hours helps to maintain this cycle. Conversely, exposure to blue light before sleep can disrupt the cycle and cause insomnia and fatigue during the following day.

How to protect yourself from blue light?

There are more possibilities, in the case of mobile devices you can use filters, whether software (applications) or hardware (tempered glass). Alternatively, you can use blue light blocking glasses. These glasses reduce the exposure of blue glass emitted by a computer or other digital device.

To immediately reduce the effects of blue light on your eyes, our product range includes three blue blocker glasses:

  • Rozelle
  • Rigi
  • Coverlite

Rozelle

Sports design goggles with Class 1 F polycarbonate visor according to EN 166. The Rozelle lens is protected against scratches and fogging. The glasses also safeguard against flying particles with low energy. The user will appreciate the practical adjustable arms. Goggles not only protect against UV radiation; colourless Blue blocker also filters 38% of blue radiation.

Rigi

No matter in which environment you work, Rigi safety goggles are the perfect blend of performance, safety and active style. It boasts a very lightweight construction (only 19g) with a low profile. The unique design adapts to a wide range of faces of men and women. The thin and flat ergonomic Flexofit side panels are then compatible with any hearing protector or helmet. The glasses are also able to block part of the blue spectrum radiation.

Coverlite

Coverlite glasses are the most comfortable goggles you can buy. Thanks to the unique construction, they are incredibly comfortable even when you wear them through your corrective glasses. At the same time, you can hardly feel them on your face as they are the lightest goggles over the goggles on the market.

The Coverlite Orange 550 provides 100% blue light protection with 380-550nm wavelengths and filters out 99.99% of the ultraviolet spectrum. Coverlite Orange 550 glasses are designed for special applications such as surface inspection, curing lamp work, vulcanization, dental and medical applications.

Coverlite IR 5 then blocks 99.99% UV (280-380nm), 97% infrared (780-1400nm) and 99% blue light (380-500nm). These glasses are designed for special welding applications.