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Eye strain used to be something you experienced from trying to read without proper lighting. It was something our parents used to warn us about when we played too many video games or sat too close to the television. In today’s day, that could still be the case, but changes in screens, light technology, and the increased use of digital devices has us experiencing eye strain earlier and more frequently.
The digital era has us questioning the health effects of blue wavelengths of light, since we can’t seem to pry our eyes away from screens, including laptops, monitors, tablets and smartphones. For many of us, our work and livelihood depend on the use of these devices. So what is it doing to our eyes?
Today, most computer and television screens use liquid crystal displays (LCDs) or light-emitting diode (LED) displays. LCDs give off way more blue light than the old cathode ray tubes that were used in big bulky computer monitors and televisions – before they were turned “flat” by these newer technologies. Increased exposure to the short wavelengths of light that these displays emit has been reported as more hazardous to human eye health1, likely because excessive exposure can cause oxidative stress to the eyes.
Light exposure, and blue wavelengths in particular, is the main cause of cellular eye stress – specifically to the retinas which capture all the light that enters through the eyes. Usually, the effects of light damage presents later in life – as early as in our 40’s, but most commonly between the ages of 60 and 80 years. However, even without major eye damage, short-term exposure to these lights and the use of screens can cause symptoms of eye strain, which can be annoying and uncomfortable.
The terms “computer vision syndrome” or “digital eye strain” (since it’s not just computers that our eyes are glued to) are used to describe symptoms of screen use such as tearing, tired eyes, blurred vision, burning, redness, eye fatigue, and even double vision.2 But it’s not only blue wavelengths of light from LED and LCD screens that are a problem. We commonly switch between devices throughout the day, which means having to accommodate different sized screens, fonts, lighting and contrast settings. For the eyes, accommodation means changing the focus of the lens and in eye alignment in order to see a clear picture. We’re basically working our eyes harder than we ever have before.
Excessive light exposure to the retinas may pose issues for vision later down the road, but right now, as you’re using your digital devices, your eyes have to deal with screen glare and constant accommodation, made more challenging by the fact that screen use changes our blinking patterns. These extra pressures put on the eyes are causing the symptoms of digital eye strain in both children and adults, and even more so since the COVID-19 pandemic.
When schools shut down in-person learning due to COVID-19, kids nationwide moved to online learning, using laptops and tablets as their primary source of learning. The prevalence of eye strain in children was around 20% pre-COVID and now averages around 50-60%3 and is even higher in those with greater than two hours of daily continuous use, including teens that regularly use smartphones.4
In one study of adolescents aged 11 to 15, the average daily use of devices was about four hours per day, which was longer than pre-COVID-19 (as reported by their parents) by two hours per day.4 More so, about 37% of students were exposed to a digital screen for more than five hours a day compared to 1.8% before COVID-19. The most commonly reported symptoms were dry and/or itchy eyes, blurred vision, and headaches.
Factors that affected these symptoms the most were the use of smartphones, having digital screens less than 18 inches from the eyes, playing mobile games for more than one hour per day, and having a total daily use of all devices greater than five hours per day.4
Digital Eye Strain
There are different symptoms that come up from being on digital devices all day, and for different reasons. If you’re getting tension headaches from sore shoulder and neck muscles, it’s likely there’s an issue with your posture and position, not something specific to your eyes or vision. Blurred vision, on the other hand, is commonly experienced from computer use when the eye’s response to a visual stimulus changes and the eyes can’t accommodate and/or focus properly. A reduced rate of blinking and incomplete blinking, both which have been associated with digital screen use, can also cause blurred vision, in addition to dry eyes, red eyes, irritation, tearing, and sore eyes.
One study found that the average blink rate went from 18.4 blinks per minute when not using a digital device to only 3.6 blinks per minute during device use.2 Why does this happen? Often because we’re trying to adjust to poorer contrast, smaller font sizes in addition to having to mentally switch between tasks and devices rapidly. All of these cause us to both blink less, and to not blink completely.
Yes, it’s common to actually not fully blink, meaning that the upper eyelid does not come down enough to cover the entire surface of the cornea (eyeball surface). Proper and complete blinking is required for eye health because it distributes tear film over the exposed surface of the eyeball, keeping them lubricated and protecting them from irritants.
3D Displays and Virtual Reality
What about other types of displays? What’s really interesting is the effect of watching 3D (three-dimensional) screens. This is one of the hardest types of screen-watching on our eyes for near-point accommodation and binocular vision. The constant adjustments for vision accommodation and convergence are reported to cause fatigue and other eye symptoms. In one study, compared to 2D screens, watching a 3D display for 30 minutes was shown to increase visual discomfort and reduce binocular convergence.5
Another study looked at the effects of playing a virtual reality (VR) game (Minecraft on an Oculus Rift VR device) for 30 minutes and found that playing in immersive mode led to significantly greater eye tearing, blurred vision, double vision, headache, dizziness and nausea, compared to the non-immersive mode.6
How can you decrease digital eye strain?
- Reduce reflections and glare. Use a matte screen cover for smartphones and tablets which will reduce reflections.
- Reposition your screen: When sitting upright at your desk or table, have your screen about 20 inches from the eyes. The height of the screen should be lower (about 15-20 degrees) from the level of the eyes.3
- Increase the text size on your screen.
- Decrease screen brightness so that it matches the light in the surrounding workspace and maintain a contrast setting around 60-70%.
- Increase your blink rate and focus on complete blinking. Be mindful and allow the eyelid to completely close over the eye so that the whole surface is allowed to be lubricated properly. Anti-reflection films and screen covers can also help increase blink rate.
- Give your eyes a break following the 20/20/20 rule: Every 20 minutes, focus on an object 20 feet away for 20 seconds. Set up a prompt or notification on your device if you need one.
- Try wearing computer glasses that block out at least 60% of blue wavelengths of light. One small study found that wearing high-blue-blocking lenses during a two-hour computer task decreased eye pain, discomfort and itchiness compared to using lenses that only cut out 24% of blue light or had no blue-blocking lenses at all.1
- Stay out of the direct flow of air conditioning vents and fans since this can accelerate eye drying. Lubricating eye drops can also help fight eye dryness.
Digital eye strain is worse in those who already have an eye condition or wear contact lenses (since they can be drying), so it’s important to keep up with regular eye exams. If you’ve been prescribed eyeglasses, wear them! Computer glasses are specifically designed to accommodate reading at a greater distance than you would normally read a book or paper, so these might also be helpful. And try opting for lenses with a blue-light filter which can help decrease the oxidative stress on your retinas.
1. Lin JB, Gerratt BW, Bassi CJ, Apte RS. (2017). Short-Wavelength Light-Blocking Eyeglasses Attenuate Symptoms of Eye Fatigue. Invest Ophthalmol Vis Sci. 58(1):442-447
2. Coles-Brennan C, Sulley A, Young G. (2019). Management of digital eye strain. Clin Exp Optom. 102(1):18-29
3. Kaur K, Gurnani B, Nayak S, et al. (2022). Digital Eye Strain- A Comprehensive Review. Ophthalmol Ther. doi: 10.1007/s40123-022-00540-9. Epub ahead of print. PMID: 35809192
4. Mohan A, Sen P, Shah C, et al. (2021). Prevalence and risk factor assessment of digital eye strain among children using online e-learning during the COVID-19 pandemic: Digital eye strain among kids (DESK study-1). Indian J Ophthalmol. 69(1):140-144
5. Wee SW, Moon NJ, Lee WK, Jeon S. (2012). Ophthalmological factors influencing visual asthenopia as a result of viewing 3D displays. Br J Ophthalmol. 96(11):1391-4
6. Yoon HJ, Kim J, Park SW, Heo H. (2020). Influence of virtual reality on visual parameters: immersive versus non-immersive mode. BMC Ophthalmol. 20(1):200.