This is part one in a four-part series guest-written by nationally recognized blue light expert, Gary Morgan, OD.
Kids today are being introduced to digital technology earlier than ever. From speech training to potty training, many boys and girls are learning to tap and swipe before they walk and talk. But while there are obvious benefits to getting our kids ahead of the learning curve on digital technology, there’ a less beneficial result of all that screen time.
According to a recent VSP® study, the average American child spends 50,000 hours (1/3 of their lives) on devices by the age of 17. So it’s not surprising to find that 55.6% of parents say their kid(s) experience at least one common symptom of digital eye strain.
But is it a case of age, anatomy, technology, or a combination of the three that’s contributing to the surge in digital eye strain among children?
In this four-part series, we’re going to examine three primary reasons why kids could be at greater risk of blue light exposure than adults, and how you as an eye care provider can help.
THE DAWN OF A NEW VISUAL WORLD
We are in year 10 of the evolution of our visual environment. The first iPhone® was released in 2007, and the first iPad® in 2010. In 2014, the final step of legislation to convert to energy-efficient light bulbs in the US was completed. These events have exposed us to more indoor blue light than at any point in human history. And there is perhaps no group taking in more blue light than children.
In addition to gaming and socializing, many of today’s children are turning to computers, tablets and smartphones for their daily school and homework activities. Pencils, erasers, and textbooks are rapidly being supplanted by a finger and a touchscreen.
THE EXPONENTIAL POWER OF PROXIMITY
Little kids are…well…little. So with their shorter arms, they’re naturally going to hold a smartphone or tablet closer to their eyes. Compounding this is font size. While adults (especially those who are presbyopic) may have larger fonts on their devices, children tend to use smaller fonts. A study of Chinese school children found that working distance decreased with smaller font size.
Common sense tells us that if we hold a light source closer to our eyes, it will be brighter than one held further away. However this increase in brightness (or intensity of blue light from electronic screens) is not linear. One might expect a child holding a smartphone at 8” is getting twice the blue intensity of an adult holding the same device at 16”. But this is not the case, as demonstrated by the inverse square law, which states:
Plugging in the math:
So a child is actually getting 4x the blue light intensity from a screen held at 8” vs. 16”
BRINGING 90% OF THE SUN’S INTENSITY UP TO OUR FACE
Let’s compare how this might relate to sun exposure, which is by far our strongest source of blue light. According to f.luxometer, an adult holding an iPhone 6 at 16” is experiencing light from the screen that is 13% as bright as daylight. A child holding the same phone set to the same screen brightness is experiencing light from the screen that is 55% as bright as daylight.
Now lets take this a step further. What if a child were to hold their phone at 2” from their eyes. The intensity of light from the screen compared to holding the screen at 16” is now 64 times, or 91% as bright as daylight. But why would a child hold a phone 2” away from their eyes you ask?
Take a look at this short video:
Pretty amazing right? Virtual reality (VR) as demonstrated in this video offers amazing potential for education and entertainment.
Augmented reality (AR) is similar, in that screens and devices (sometimes placed directly in front of the eyes) are used to superimpose a computer-generated image on a user’s view of the real world. The recent Pokemon Go game is an extremely successful example of augmented reality.
How will these new technologies affect young patients? While a scientifically proven answer to that question may not be available for some time, a proactive approach to reducing blue light exposure from these devices at close proximity is certainly more responsible than a wait-and-see approach.
In part 2 of our series on kids and blue light, we’ll be discussing pupil size and why it could be a gateway for blue-light-related issues in children.
1. VSP, “Should You Be Concerned About Blue Light Exposure? (Infographic), 2015, View Article
2. The Vision Council, “Eyes Overexposed: The Digital Device Dilemma, 2016
3. Wang Y, et al. Reading behavior of emmetropic schoolchildren in China. Vision Research 86 (2013) 43–51.
4. fluxomter for adult set at age 35, 16” away at 100% brightness resulting in 13% equivalence to sunlight. fluxometer for child set at age eight, at 8” at 100% brightness resulting in 55% equivalence to sunlight. www.fluxometer.com