The true relationship between screens, books and myopia | Society

Surely on occasion we have heard or read that the excessive use of screens is causing an increase in cases of myopia. And that this relationship is direct, that is, the screens are responsible for the fact that there are more and more myopic people in the world. Not surprisingly, there are studies that conclude that those children who spend more time in front of books or screens develop more myopia than those who spend a limited time.

Not only that. We have always assumed that myopia and the use of glasses is directly related to the execution of tasks that require special visual effort. Or with very studious people, or an avid book reader throughout his life.

As we have lately replaced many of these paper reading tasks with electronic screens, we have shifted responsibility from one culprit to another.

However, this long-assumed direct relationship has not been scientifically proven. Although it is taken for granted by the hypothesis of correlation / causality, one must be careful with these parallels, since correlation does not always imply causality.

This is well explained by Tyler Vigen, a Harvard attorney. In his web page Spurious Correlations (or Spurious Correlations), has maintained for years a statistical experiment with arbitrary data obtained from different sources and that, when overlapping them in graphs, generate the most crazy correlations. For example, from their data it can be deduced that between 2000 and 2009 there was a correlation between the increase in per capita cheese consumption and deaths from entangling with sheets. Absurd, right?

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What is certain is that the increase in cases of myopia is real and that it cannot be fully explained based on genetic factors. Therefore, you have to look among environmental factors.

Complicit but not guilty

Are screens – or rather their excessive use – the origin of the problem of myopia? The latest studies suggest that the screens are only accomplices of this reality, but not the direct culprits.

Myopia, which results in difficulty in focusing on distant objects, is due to the eyeball being too long in relation to the focusing power of the cornea and lens of the eye. This causes the light rays to be directed to a point anterior to the retina.

We are also myopic when the cornea, lens, or both are too curved for the length of our eyeball. And in some cases, all these factors concur simultaneously.

These anomalies are corrected with lenses that guide the light information to the back of our eye.

The process by which an eye develops myopia is not fully known, but what is known is that for our vision to develop correctly we need to promote and practice both near and distance vision.

In this sense, it seems logical to suspect that continuous exposure from an early age to screens at a time when the eye is still maturing may favor the development of vision of nearby objects, to the detriment of long-distance vision. However, there are insufficient data to conclude that this factor is behind the development of myopia.

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Eye fatigue

What nobody disputes is that the excessive use of screens causes “eye strain”, also known as “computer syndrome”, which translates into redness, stinging and itching of the eyes, dry eyes (or otherwise, constant tearing), pain upside down, etc. It is because when we look at a screen we blink less (unconsciously), we stare at a specific point for a long time or from an inappropriate angle, we expose ourselves to the excessive brightness of these devices, etc.

How do you fight? No filters that block blue light – which is unfairly responsible for this evil. The best recommendation to reduce the signs of eye fatigue is to blink frequently and take breaks following the 20/20/20 rule. That is, every 20 minutes take a 20-second break and look at (and try to focus on) an object 20 feet away (6 meters).

If it is looking through a window and with light, the better. Why with light? Because it is suspected that one of the possible culprits for the development of myopia is the lack of light.

The real problem is the lack of light

Indeed, it has been proven that what children with a lot of reading activity have in common, whether on paper or on a digital screen, is that they are less exposed to sunlight during the day. In fact, it has recently been shown that there are indeed a relationship between myopia and the absence of sunlight.

Apparently, solar radiation (especially high-energy radiation, such as blue and violet light) would stimulate the release of dopamine by the amacrine cells of the retina (another cell type different from photoreceptors). That would inhibit the growth of the eye, preventing the typical lengthening that leads to myopia.

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There is also experimental evidence that shows that in different animal species, including monkeys, exposure to high-energy violet light could protect against myopia.

In sum, everything indicates that neither books nor electronic devices are the direct culprits of the increase in myopia in the world. They have only become complicit in this phenomenon by keeping children out of the sunlight.

How do we solve it, then? Simply doing more outdoor activities.The Conversation

Conchi Lillo, Professor of the Faculty of Biology, researcher of visual pathologies, University of Salamanca

This article was originally published on The Conversation. Read the original.

The Conversation

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George Holan

George Holan is chief editor at Plainsmen Post and has articles published in many notable publications in the last decade.

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