It has been about a year since COVID-19 forced a significant change in lifestyle for everyone. Many people started working and learning from home, spending more time indoors and on computers and digital devices. Listening to patients over the past year suggests that this increase in screen time has a noticeable effect on eye comfort for many. What’s more, news stories and social media posts speculate about whether exposure to the lower wavelength (blue) component of the light emitted by these screens can affect your level of wakefulness or even cause damage to the eyes over the long term.
Computer Vision Syndrome is an established term describing how the eyes are impacted by digital device use. The syndrome can essentially be broken down into two parts: eye dryness and alignment/focusing problems. Looking at a computer screen causes us to blink less often, which leads to the break-up and evaporation of the tear layer on the surface of the eye. This causes symptoms of dryness, burning, and blurred vision. Our screens (especially phone screens) are also often very close to our eyes, requiring the eyes to turn inwards (converge), and focus (accommodate) for long periods of time. Convergence and accommodation require muscles in and around the eye to work, and over a full day of screen time these muscles can feel tired and sore. Anecdotally, blue light may seem a bit harsher to the vision, particularly in the evenings and in dimly lit settings. However, neither dryness nor eye muscle fatigue have been shown to have a direct link to blue light itself.
Some sources claim that blue light from screens can cause damage to the retina over long periods of exposure; however, studies to date have not produced evidence supporting this claim. Blue light is higher in energy than other visible wavelengths, and excessive exposure has been shown, in addition to UV light, to increase the risk of Age-Related Macular Degeneration. However, the amount of blue light emitted by our screens, even over an entire day, is miniscule in comparison to the amount of blue light we receive from the sun just from being outdoors.
Further research suggests that blue light from screens has an impact on sleep-wake cycles and circadian rhythm. IPRGCs (Intrinsically Photosensitive Retinal Ganglion Cells) are cells in the retina that detect low wavelength (blue) light and send that information to the area of the pineal gland of the brain, which controls our sleep cycles. The theory is that blue light from the daytime sun tells our brains to stay awake, and redder light during the evening signals the brain to start to prepare for sleep. Since our devices are providing constant blue light regardless of the time of day, this signals to the brain that it should still be awake and can result in difficulty falling asleep.
So what’s the verdict? The evidence that we have to date suggests that exposure to blue light emitted by screens is not a significant risk for long term damage to your eyes, nor does it factor into eye fatigue from prolonged screen time. More effective strategies for those who are concerned about light damage to the eyes would include wearing UV-blocking sunglasses when outdoors, and giving your eyes frequent breaks throughout the day during extended screen time can help prevent eye fatigue (a popular cue is the 20-20-20 rule: every 20 minutes, look at something at least 20 feet away for 20 seconds). Smoking cessation, good nutrition, and exercise are also well-established factors in protecting eye health. It may be worth considering how the blue component of light from screens impacts falling asleep, or whether it feels bright and harsh to look at. However, both issues are easily and freely solved with settings or apps that shift the colour of your display towards a redder hue in the evenings. In short, even though they will likely not harm your eyes, there is no known benefit to wearing blue-light-filter glasses for the purpose of preventing eye damage indoors. If extended screen time is uncomfortable for you, or if you have concerns about the effect of blue light on your eyes, make an appointment with your optometrist to have an assessment and develop preventative strategies.
Dr. Liam Teeple, OD BSc