Tablets have become a part of our day to day life. The ease and convenience of a tablet just can't be beat. Where else can you take thousands of books with you or download the latest newspaper or magazine issue on the go!? But is there a cost to our eyes from using these devices?
There is no long term damage to your eyes from reading on a tablet. But tablets can cause short term eye trouble such as eye strain. These eye problems can be avoided by using tablets utilizing digital ink or e-ink such as ebook readers.
Some of these problems also be avoided by using good old-fashioned paper as well. But simply reading in general can cause you to have some problems with the eyes - known as eye strain. And there are multiple different ways this eye strain is caused.
Reading Overworks Our Focusing Muscles
When we look up close at a tablet, or your phone or a book, we have to change the focus inside our eye to see up close. When we are young, this happens automatically without us even realizing or thinking about it. We just can see up close.
Within our eye is a special muscle called the ciliary body. The ciliary body muscle is attached to the natural lens inside our eye. When we look up close, this muscle flexes to change the shape of our natural lens. The shape change of this lens allows us to see up close.
How the eye focuses up close, image by MikeRun, CC BY-SA 4.0, via Wikimedia Commons
If you are reading for an extended period of time, this muscle can get tired just from being overworked. When this muscle gets tired, frequently it will ache and cause you to have a headache. This muscle can also have a harder time flexing causing you to have more blurry vision. These are all symptoms of eye strain.
What's the solution then? Take a break from reading. This will give the ciliary body muscle time to relax.
Special note about presbyopia: eventually for everyone, the lens becomes less flexible and has a harder time focusing up close. This occurs during our 40s and 50s and requires us to use reading glasses or progressive glasses to see up close. Because our ability to focus up close diminishes, this can cause more eye strain since our ciliary body muscle has to work harder and things are more blurry without additional correction.
Reading Dries Our Eyes Out
The second issue with simply reading is that we don't blink our eyes as frequently as normal. Normally, we blink approximately 15-20 times a minute. This equates to a blink about every 3-4 seconds. But during tasks which require our attention such as reading, our blink rate can drop to about 4-6 times a minute. This equals a blink about every 10-15 seconds! Our blink rate can become almost 5 times slower!
On the surface of our eye is a tear film. Having a smooth and intact tear film prevents our eyes from drying out. Every blink of our eyelid allows us to replenish our tear film and make it smooth. Thus, if we aren't blinking as frequently, the tear film can dry up and our eyes can dry out.
Dry eye can cause your vision to become blurry. It can also cause your eyes to burn and ache as well.
This is especially important as we get older, as our eyes become more susceptible to dry eye; making preventing and treating it even more essential.
So what can be done? Using artificial tears during reading tasks can help prevent the eyes from drying out. If you do have any more long-term symptoms of dry eye, it is also helpful to use artificial tears more routinely or visit your eye doctor for more recommendations.
The Problem With Tablets
Reading from a tablet carries all of the eye strain issues that reading in general carries. But reading from a tablet also has additional ways our eyes can develop eye strain.
The light from a tablet can cause eye strain.
You may wonder how the light from a tablet can cause any issues. I mean, there are lights all around us. How can the light from a tablet be any different?
Is blue light the issue? Surprisingly no. Despite all of the attention blue light receives, blue light isn't harmful to the eyes. (Blue light is harmful if you are trying to get to bed, however).
Without light, we wouldn't be able to see anything. But our eyes also adjust to the ambient light in the surroundings. Too much extra emitted light from a device just can be visually exhausting over time. This is the reason why dark modes have become popular among computer programmers who work long hours in front of screens. Having the screen match up with the environment will just lead to less visual fatigue and eye strain.
Text can be harder to see on a tablet
In addition, sometimes tablets can be harder to read. The contrast between the letters on the screen isn't 100%. Black ink on white paper provides the best contrast for reading. But tablet screens, especially LCD screens can't produce very deep levels of black and this reduces the contrast between the letters. This reduced contrast can make things just a little more difficult to read and cause eye strain over time. This has improved gradually over the years with the invention of new screen technology, but LCD screens can't match physical paper.
What About E-Ink or Digital Ink Tablets?
There are two big reasons why digital ink screens such as those found on an Amazon's Kindle or Barnes & Noble's Nook can reduce eye strain: contrast and brightness. Digital ink screens can achieve a level of contrast on par with actual paper. This makes it easier for us to discern text and improves our ability to read.
Amazon Kindle; Image courtesy of Amazon.com
In addition, digital ink screens reflect light. This is different from other tablet screens which generate light. As a result, digital ink screens have brightness levels appropriate to your environment.
When outdoors in the sun, digital ink displays can also reflect less direct sunlight back towards you. This sunlight is instead diffused throughout the reader to help illuminate the screen. Traditional tablets with a glass coating, however, can reflect much more of the sun back towards your eyes causing glare and making the screen hard to see.
Because difficulty reading text because of contrast and an increased brightness both contribute to visual fatigue and eye strain, digital ink screens are better than traditional tablets to reduce eye strain when reading.
When using digital ink screens and eBook readers, it is still important to still take breaks from reading. Eye strain can still occur from prolonged focusing up close. Taking breaks ensures that the focusing muscle of the eye is given a chance to relax.
Summary
Tablets are great technologies that have improved our lives in many ways. But tablets can cause short-term eye strain and visual fatigue. As with other forms of reading, taking breaks can help. Switching to a tablet utilizing e-ink or digital ink, such as an ebook reader, can help improve the visual fatigue from tablets.
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