The use of digital devices has increased significantly in the recent past, exacerbated by the high prevalence of smartphones that are checked many times per day and used for internet searches. These devices also make it easier for use at any time, any place, including right before going to bed. As such, concerns have been raised over the impact of digital devices on individuals’ eye health and sleep quality, usually focusing on the blue light emitted from most digital devices. Headlines in research and news articles are often in contrast to one another regarding the potential hazard of exposure to blue light from smartphones and computer screens. So, what is blue light and how do blue light glasses work? More importantly, do blue light blocking glasses actually work?
What is blue light?
The visible light spectrum refers to the light that is visible to the human eye. It is broken down into categories of light wavelengths in which a particular colour is observed by the human eye. Short wavelengths on the visible spectrum ranging from 400-500 nanometers (nm) are observed by the human eye to be the colour blue. Blue light exposure is usually experienced in the form of sun rays, LED fluorescent lights or digital devices. Each source has different amounts of blue light exposure with sun rays emitting higher amounts of blue light than the display screen of a mobile phone or computer.
Not all blue light is harmful for humans. In fact, blue light is necessary for important functions such as regulating our circadian rhythm which allows us to routinely fall asleep at night and be awake during the day. Blue light also supports the human eye to quickly adjust to a dark room. It can become hazardous when the human eye is overexposed to blue light, especially if the blue light is short-wave, ranging from 415nm to 450 nm, which is the most damaging blue light. For example, overexposure to sunlight over a lifetime can result in the development of cataracts, which impairs a person’s vision.
There are reported negative health effects associated with exposure to blue light from digital devices. For example, prolonged digital device use during the night can cause a disturbance in the hormone production involved in regulating circadian rhythm. This means that using digital devices for long periods of time throughout the night can interfere with an individual’s ability to fall asleep. Further, many studies using animal and cell models show that long-term exposure to blue light from digital devices causes damage to the retina which is where our vision forms; however, it is important to note that there have been few meaningful results on human retinal damage. For this reason, the American Academy of Ophthalmology (AAO) claims that the small amount of blue light emitting from devices will not likely cause serious eye damage. The AAO does state that prolonged digital device use, rather than blue light exposure, can result in a variety of symptoms of digital eye strain such as eye fatigue, dry eye, blurred eyesight, and headaches. These can be uncomfortable symptoms for many people but they are temporary, and in most cases, not severe. Still, many people are interested in blue light glasses.
How do blue light glasses work?
Blue light spectacle lenses (glasses) are one of three available products for blocking blue light associated with digital devices. In addition to glasses, both contact lenses and intra-ocular lenses (implants) are available forms for blue light-blocking. All three forms work through the mechanism of a dye which absorbs only blue and violet light. This means that the blue light does not get absorbed by the human eye since the glasses have already done so. Alternatively, some lenses will just reduce the amount of blue light reaching your eyes by absorbing only some of the blue light. The blue light lenses either contain or are coated with this particular dye, allowing the lenses to completely block or filter out blue light while the user is wearing them. These devices claim to reduce eye strain, improve sleep quality, and prevent eye degeneration if an individual wears blue light glasses while on their digital devices.
Do blue light-blocking glasses work?
A recent review of the current research on the efficacy of blue light-blocking glasses reported that there is a lack of high-quality evidence supporting the use of such glasses to alleviate eye strain, prevent sleep disturbances, and protect eye health. One study evaluating blue light glasses compared to clear lens glasses (i.e., no blue light-blocking capability) determined that participants did not notice a significant change in visual comfort or relief from eyestrain between wearing blue light glasses and the control. The study did report however, that there were improvements in the participants’ vision for computer and digital phone screens. In terms of sleep quality, research, including animal and human studies is inconclusive as to whether blue-light blocking glasses improve sleep quality after using digital devices throughout the night. Blue light-blocking glasses can be expensive and have received mixed reviews from scientists on their efficacy.
Alternatives to blue-light glasses
Alternative methods to prevent both digital eye strain and interference with circadian rhythm can inlcude cutting down on screen time at night to limit exposure to blue light before sleep. The American Academy of Ophthalmology suggests using the 20-20-20 rule in which an individual takes a break from their screen every 20 minutes to look at something 20 feet away for 20 seconds. This may help prevent and/or alleviate the symptoms of digital eye strain. Lastly, wearing proper sun protection (i.e., sunglasses) and limiting sun exposure can help reduce the risk of overexpose to ultra-violet and blue light rays from the sun which can damage the retina over time.
Written by Megan Cisecki
References:
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Lawrenson, J. G., Hull, C. C., & Downie, L. E. (2017). The effect of blue‐light blocking spectacle lenses on visual performance, macular health and the sleep‐wake cycle: A systematic review of the literature. Ophthalmic and Physiological Optics, 37(6), 644-654.
Leung, T. W., Li, R. W., & Kee, C. S. (2017). Blue-light filtering spectacle lenses: Optical and clinical performances. PloS One, 12(1), e0169114. https://doi.org/10.1371/journal.pone.0169114
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Image by Krzysztof Kamil from Pixabay
