Just what is a blue light filter? The sun, indoor lights, your computer, phone, and other digital devices – all these expose you to different light rays. You probably already know that sunlight contains white light as well as the infamous invisible ultraviolet rays. However, what may surprise you is that the visible white light emitted by the sun isn’t a single entity. It’s composed of a range of different colours that contain different amounts of energy.
What is blue light?
Visible light contains red, orange, yellow, green and blue rays and their many shades. These are all determined by their wavelengths and the energy carried by the individual rays. Without delving too deep into complicated physics, there’s an inverse relationship between wavelength and energy in waves. As a result, red light on one end of the light spectrum has longer wavelengths and therefore, less energy. The blue light on the other end of the spectrum has shorter wavelengths and more energy.
In the entire electromagnetic spectrum, visible light falls between the wavelengths of 380 nm and 700 nm. Blue light or high-energy visible (HEV) light is essentially light ranging from 380 to 500 nm. That is roughly a third of all visible light. In More Detail
Just beyond the red end of the spectrum of visible light are the infrared rays. These are invisible waves that pass along heat. On the blue end of the spectrum, rays with the highest amount of energy are sometimes called blue-violet or violet light. Fittingly, the invisible electromagnetic rays just beyond them are called ultraviolet (UV) rays.
UV rays have higher energy than visible light and are therefore able to significantly affect the skin. That’s how you get a suntan. As a matter of fact, the bulbs in tanning booths emit controlled amounts of UV radiation for this exact reason.
All you should know about blue light
However, too much exposure to UV results in sunburns and can even lead to skin cancer. Like many things, UV rays in moderation can have benefits like the production of vitamin D.
Just like its close neighbour in the electromagnetic spectrum (UV light), blue light has both benefits and dangers. Here are some key points to note about blue light:
Blue light is all around you
The main source of blue light (and all light in general) is the sun. As a result, simply being outdoors during the daytime gets you the most exposure to blue light. In addition to the sun, there are also numerous manmade sources of blue light. These include fluorescent and LED artificial lighting, as well as the screens of all your digital devices.
The quantity of blue light emitted by these devices is a bare fraction of that emitted by the sun. Despite that, these devices have many people worried about the possible long-term effects of blue light. This is due to the mind-boggling amount of time spent using these devices coupled with the close proximity to the screens. Blue light is why the sky is blue
Why is the sky blue? It’s one of those common questions that surprisingly few people know the answer to, and that answer is blue light. HEV light, by virtue of having a short wavelength, flickers and scatters more easily compared to other visible light rays. So when light from the sun strikes air and water molecules present in the atmosphere, blue light scatters more. The scattered blue light is what makes the sky appear blue.
Your eyes aren’t good at blocking HEV light
The anterior structure of your eyes is very effective when it comes to blocking UV rays from reaching the retina. More specifically, the cornea and the lens in the eyes block more than 99% of UV rays from the sun. That’s even without wearing any kind of protective eyewear. Unfortunately, this isn’t the case when it comes to blue light. Virtually all of it passes through the cornea and lens to reach the retina.
Exposure to blue light puts you at risk of macular degeneration
The fact that blue light passes unhindered all the way to the retina is a cause of concern. Studies have shown that too much exposure to blue light can damage the sensitive photoreceptors in the retina. The end result is a similar picture to that of macular degeneration which can lead to permanent vision loss.
Even so, a lot of scepticism remains as it hasn’t been determined exactly how much blue light is ‘too much'. Many eye care specialists, nevertheless, remain concerned that hours of screen time could increase your risk of macular degeneration. HEV light plays a part in digital eye strain
As previously mentioned, blue light tends to scatter more easily than other wavelengths of visible light. When you’re looking at your laptop, your smartphone or other digital devices that emit blue light. This scattering makes it hard to focus, reducing contrast and clarity. The resulting straining contributes to
Protection from blue light may be more crucial after cataract surgery
As you age, changes in your eye’s natural lens help it block some HEV light. More importantly, it blocks the type of blue light most likely to damage the retina and leads to macular degeneration. If you’re about to undergo surgery to get rid of cataracts, you could lose this natural protection. It’s therefore prudent to find out what type of intraocular lens will replace your natural ones. Also, figure out how much protection against blue light your new intraocular lens will provide.
Blue light protection from your natural lens is lost after cataract surgery, so you’d benefit from blue light glasses. This is particularly true if you usually spend a lot of time in front of a screen.
Blue light can be beneficial
Some blue light exposure is beneficial, particularly during the day. It has been documented to boost alertness, memory, reaction times and mood. That’s why blue light is used as therapy for the treatment of seasonal affective disorder (SAD). It’s a type of depression that typically occurs during fall and winter when there’s less exposure to sunlight.
Blue light is also important for regulating the circadian rhythm or sleep cycle. Daytime exposure to blue light helps maintain a healthy circadian rhythm. However, too much blue light at night disrupts your sleep cycle, leading to insomnia and fatigue.
Blue light filters
If you use a laptop or smartphone, you can limit your blue light exposure by using a blue light filter. They are available for smartphones, tablets, laptops and desktop computers and work by selectively filtering out the blue light emitted. They also have the additional benefit of protecting the screen of your device from scratches or cracks.
Blue light blocking glasses are also very effective when it comes to reducing blue light exposure. They limit exposure from not only your digital devices but also other sources of blue light like artificial lighting. They are easily available and can be acquired even without a prescription. Alternatively, you can buy a specially prescribed pair to optimise your vision for the viewing distance of your device.