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How to Test Blue Light Glasses?
We spend more and more time staring at our computer screens at work, only to go home and continue our obsession with electronic devices. Digital LED screens shower us with high-energy blue light. While we get most of our blue light from the sun, our eyes are not designed to handle it for so many hours and at such a close proximity when the sun goes down.
Studies show that overexposure to blue light may be linked to digital eye strain, increased risk of macular degeneration, and interruption of sleep patterns.
One of the best ways to give your eyes a well-deserved rest from blue light over-exposure is to buy glasses with blue light blocking lenses. Not all blue light blocking glasses are created equal and many are not as effective as they claim to be. If you have any concerns about whether they work or not, there are ways for you to test your specks.
Before we talk about different tests for your computer glasses, we should first talk about color perception, blue light, and blue light filters.
How Do We Perceive Color?
We look around and we see this amazing world full of colors that makes us smile, remember happy memories, and feel at peace. All of us have admired the photos of the turquoise blue colors of the Caribbean, reveled in the orange hues of a sunset, soaked in the vibrant magenta of a bougainvillea, gazed at the bursting yellow of a perfectly ripe mango, and melted with love looking at the blue-gray shade of our child’s eyes.
Would you be surprised if you found out that objects do not actually possess color? It is our brain that translates millions of cues our eyes send into those beautiful images that make our life beautiful. And it’s all because of light.
Light is just a type of electromagnetic radiation that emits waves, and each color has its own wavelength and energy. The visible spectrum for human eyes falls between red and violet light, and according to the scientific world, we can distinguish up to 10 million colors.
When light reaches an object, it absorbs some of the light and reflects the rest of it. That reflected light is what our eyes and brain process to give us a sense of color. The reflected light enters the eye through the cornea, which is the outermost part of the eye.
The cornea swivels the light towards the pupil, which controls the amount of light that reaches the lens (this is the reason your pupils dilate in the dark and become smaller with brightness). The lens then sends the light to the retina, the innermost layer of the eye that contains light-detecting cells.
The retina contains two different types of light-detecting cells – rods and cones. Rods react when you are in low or dim light, when the objects appear gray. The cones are activated when there is sufficient light, and when that light reaches your eye, depending on the wavelength, a specific type of cone (red, green, or blue) will react and send the signal to the visual cortex of the brain along the optic nerve, which processes the data and forms a mental picture of the image. Most of us have about 6 million cones and 110 million rods.
What is Blue Light?
The human eye can register wavelengths from 380 to 740 nanometers. Blue light rays are the ones with the shortest wavelength but with the most energy, which is why they are called high-energy visible (HEV) light rays. When we look at the sun, we don’t stare long enough for it to cause damage, as the sunlight hurts our eyes. But, we do spend seven to ten hours a day in front of our computer screens or scrolling on our smartphones at close range, which can also cause damage.
Blue light is not filtered, which means that it penetrates deep into our eyes all the way to the retina.
Recent studies have found that extended exposure to blue light has many adverse effects to our eyes and overall health:
- disruption of the circadian rhythm
- insomnia
- digital eye strain
- macular degeneration
- blindness
Blue light is not all good or bad. In daylight, it boosts our mood, makes us more alert, and gives us energy to complete all those spreadsheets and catch up with our PTA responsibilities. But come night-time, our circadian rhythm kicks in and we want to wind down, relax, and get ready to sleep.
Most of us admit we take our digital devices to bed with us to binge watch our favorite shows or to stay current on our social media feed. This is when blue light becomes our enemy, as it suppresses the production of melatonin, our sleep hormone, so we are restless and unable to fall asleep, which hampers our productivity the next day.
How Do We Test Blue Light Blocking Glasses?
Daytime blue light filters are specifically designed to eliminate the most harmful frequencies between 400 and 450 nanometers, which damage the light-sensitive cells on our retina if we are exposed to too much of it. They still however let some of the blue light come through while lessening our eye strain, as some blue light is needed to regulate our circadian rhythm, help us stay alert and focused, help us be more productive, and give us more energy during the day.
Some filters however are designed for night-time use, and they block blue light in frequencies up to 480 nm. With the production of melatonin uninterrupted, we can relax and get a good night of sleep.
Nowadays, you can buy a blue light filter screen for your computer or tablet, and newer smartphones are equipped with some form of blue light protection and night mode. If you’d like only to reduce the glare on the computer screen, then a free software like flux may be sufficient. But, if you are looking to filter blue light, you’ll need ophthalmic lenses with protective coating that is designed to reflect and filter high energy blue light.
In recent years, there have been many companies producing blue light blocking glasses. But, how do you figure out if they do what they claim to do?
Clear lens computer glasses should be worn during the day only, as they are not designed to block out blue light completely, but rather filter it and relieve the symptoms of overexposure to blue light while staring at a computer screen.
To be sure the glasses you choose truly filter out blue light, you should contact the retailer and ask for a transmittance spectrum report, which will show you the percent of light passing through the lens.
In order to be functional in filtering blue light, your blue light glasses should filter down at least 30% of blue light across the entire blue light range. Most reputable companies will make these reports available upon request, but in case you cannot obtain one, visit your eye doctor and ask them to test your glasses with their lab-grade spectrometers.
While you are waiting for the spectrum report, you can conduct a few tests at home, too.
One of them is to put your glasses on and observe the color that is reflected off the lenses. If the reflection is purple, that’s an indication that they are not filtering blue light effectively. If it’s blue, they are filtering at least some of it.
Another reliable way to test your blue light glasses at home is to use the RGB color circle test. Most of our computers and digital devices use a technology called Liquid Crystal Display (LCD). The screens are composed of many pixel panels and each pixel has a red, green, and blue component. There are many variations of these three colors which produce all the hues you see on a screen.
Put on your blue light glasses and check out this RGB color model.
The blue part of the image should appear darker or black, and the green section might darken as well. The darker the sections appear, the more blue light is being filtered. You shouldn’t be concerned if the green section changes only slightly – only blue light blocking glasses intended for nighttime will block some of the green light as well.
If a company tries to sell you a “laser testing pen,” be advised that this method doesn’t work for testing blue light. It is only intended to test violet to ultraviolet light, which will not serve any purpose in testing your computer glasses.
Summary
Blue light glasses are a good choice if you spend too much time in front of the screen. But, make sure you get the right pair that will actually do what they are supposed to do.
When you are ready to buy yourself a pair of stylish blue light glasses, do your research and ask the retailer to send you a transmittance spectrum report along with your specs.
If they are hesitant, you might want to look to spend your money elsewhere.
Sources:
https://www.livescience.com/32559-why-do-we-see-in-color.html
https://www.aao.org/eye-health/tips-prevention/how-humans-see-in-color