Everything You Need to Know About Blue Light Filters and Eye Health

Consider light as electromagnetic radiation with an enormous range in terms of frequency, energy, and wavelengths – from gamma (as tiny as 1 trillionth of a meter) to sub radio (as big as the universe since there’s no theoretical upper limit). Somewhere between the two extremes exists the very tiny fraction human eyes can detect, which is known as the visible spectrum, with wavelengths in the range of 400 nm to 700 nanometers (nm).

The visible spectrum includes the colors of the rainbow: Red, Orange, Yellow, Green, Blue, and Violet. It’s crucial to note that blue light rays have the smallest wavelengths (380 nm to 500 nm) out of all the colors in the visible spectrum because they have the highest energy photons.  Various technologies that light up the displays of the electronic devices use wavelengths in this range.

However, the biggest source of blue light is the sun, which is known to be crucial in many ways. As such, it’s fair to ask, how bad can blue light truly be? On an evolutionary scale, not long ago humans lived outdoors and were ruled by the sunrise and sunset. That’s why a blue-light-sensing protein called melanopsin exists in human eyes. The bright daylight activates melanopsin, thus synchronizing the internal clock to raise alertness, boost reaction times, and mood. However, melanopsin is less sensitive to lower energy light in the visual spectrum, which allows for the production of a sleep-inducing hormone called melatonin as the sun goes down.

The problem in today’s world is that 90% of our time is spent indoors under artificial light, thereby resulting in a deficit of direct sunlight during the day and overexposure to bright light in the evening. This combination has resulted in consequences to the natural circadian rhythm – or the master clock – of the human body. Unsettling the circadian rhythm paves the way for many of the prevalent diseases experienced in the 21st century, such as depression, anxiety, and obesity.

Additionally, although inconclusively, scientific studies also suggest a connection between blue light exposure and macular degeneration, which the leading cause of vision loss in the US! As the years go by, the natural protective layer starts to become more and more permeable to UV and HEV rays that easily penetrate to the retina due to their shorter wavelengths.   Recently, a Taiwanese woman developed a hole in her retina after years of using a smartphone outdoors. Dr. Hong, a doctor of Ophthalmology at Fooyin University in Kaohsiung, believes that the combination of the blue light emitted from the cellphone, and the ultraviolet light emitted by the sun led to this condition.

It seems as though blue light is both extremely beneficial and extremely dangerous. The best thing to do is to find ways to optimize the blue light intake during the day and regulate the exposure as the sun goes down. Thankfully, even NASA is invested in helping with this!

Most computer screens today use a type of panel with layers of liquid crystals between pairs of filters and electrodes; these are known “Liquid Crystal Displays” or LCDs for short. LCD panels require an external source of light to produce visible images. As such, LEDs are now the industry favorite for the task, after dethroning CCFLs due to size, efficiency, and cost.

The array of LEDs is often placed behind the panel or around the edges of the screen providing a bright light source. The most common type is referred to as white-light LEDs, and they combine the emission from a blue LED (around 450nm to 470 nm) with a yellow phosphor. This combination looks white when viewed directly and it’s the reason why so much blue light is being emitted from computer screens and other electronic devices.

To make matters worse, white-light LEDs are known to suffer from degradation over time, thereby causing an increase of blue emission. This degradation happens primarily through the bleaching of phosphors so that they no longer efficiently absorb blue light, thus leading to further eye strain.

Now armed with the knowledge of the different sources of blue light as well as the various health risks associated with it, if you want or need some computer time after sunset hours, you would be wise to invest in a blue light filter for your PC.

For starters, and depending on your operating system, you may have the option to turn on Night Light (Windows 10) or Night Shift (macOS). Nevertheless, a recent study on the lack of effectiveness of Apple’s Night Shift regarding melatonin production may be a strong enough reason to consider other options, such as computer screens with integrated blue light filters capable of reducing up to 87% of all blue light emissions and allowing for maximum user customization with different levels of protection and accurate RGB color balance.

This technology allows you to easily adjust the amount of blue light that is being emitted using a scale from 0 to 100 (where 0 represents the minimum level of blue light emission, meaning 87% of all blue light is being filtered out). You can set the filter to different levels depending on the viewing scenario. Most users prefer to max out the filter (0-25) when reading or using text-based applications, making it easy on the eyes.  For web browsing or work-related tasks, you might want to allow in some more blue light by setting the filter to 25-50. These daily activities should remain comfortable with this level of blue light reduction. When the main activity is related to high-definition multimedia, you can set the filter to 50-100. At 70 you receive better color balancing with sufficient blue light reduction without visible change in color.

As mentioned previously in this blog, NASA developed special LED modules for the ISS (International Space Station) in order to help keep astronauts healthy during their stay in outer space. The former NASA scientists who came up with this ingenious solution are now devoted to bringing the same technology to the general public. These modules shift the peak output according to the time of the day and use an emission spectrum that closely imitates that of the sun during the day, while eliminating the short wavelengths from blue and green light when in pre-sleep mode.

Other valid alternatives, if your primary purpose is to reduce digital eye strain, include the use of third-party software such as f.lux or Iris, as well as blue light blocking eyewear (please refer to a professional when choosing eyewear that filters or blocks blue light as these products may include magnification and specific optical centers). Although proper eyewear seems to be most effective against the harmful effects of blue light, there are at least three aspects to consider:

1. The Price: which is heavily dependent on the quality of the lenses.
2. The Fit: which needs to be tight or else blue light still reaches the eye.
3. Most blue light blocking glasses are difficult to use when overlaid against regular prescription glasses.

All in all, PC monitors with built-in blue light filters present the most convenient solution when compared to these options.