ABC Health

Screen time is bad for your eyes - but not as bad as you think

ABC Health logoABC Health 25/05/2019 6:50:00
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As a child, the warning to keep your distance from the television set was bizarre but chilling.

"You'll get square eyes," parents warned.

Of course, I knew my eyes would not be transformed into optical cubes, but the hysteria around TV proximity lingered.

Ogling the idiot box couldn't be good for you, we figured, although we trusted it more than the microwave.

Now that screens don't require two strong men to carefully place them in an entertainment unit, the threat seems more pervasive.

Laptops, tablets and smartphones are portable and often sit right up in our faces.

Many of us feel uneasy about what staring at a screen could be doing to us.

Short-sightedness on the rise

Scott Read, an associate professor of optometry and vision science at Queensland University of Technology, says myopia, also known as short-sightedness, has reached epidemic proportions.

In places like Singapore and Hong Kong, he says, the rate of myopia among young people is somewhere between 80 and 90 per cent.

While myopia is more common among people of East-Asian ethnicity, short-sightedness is a global problem.

The UN estimates that more than 50 per cent of the world's population will have myopia by 2050.

By contrast, in 2010, an estimated 27 per cent of the global population were short-sighted.

Step away from the screen (but not for the reason you think)

About a decade ago, I needed glasses only to take in every pore of the extreme close-ups at the movie theatre.

Now, I'm using the glasses I've been prescribed to see in the distance to view my computer screen.

I went back to my optometrist Hendrik Ferreira to find out what's going on.

During my last two years of uni, when I was also working pretty much full-time, my vision declined by one unit.

Half a unit over two years, Dr Ferreira says, would have been the expected rate of decline for someone with short-sightedness like me.

After four years of working full-time, my vision declined by another unit.

I assumed this was thanks to my sharp increase in screen time - despite being a regional journalist who was often out in the field, or more accurately, a paddock, I spent most of my day staring at a computer.

But Dr Read says it's likely there's a more indirect link between screen time and vision decline.

"There is not a lot of strong evidence showing a direct link between screen use and myopia," he says.

However, "using screens all the time is one reason that might stop children going outdoors".

Time in the sunshine appears crucial to developing good vision, with the World Health Organisation suggesting children spend more than two hours a day outside.

In 2015, Dr Read found that spending time outdoors can slow the progression of myopia in children.

Another study, where Chinese students were forced to spend their recess outside, drew a similar conclusion.

After one year, the students who had more time outside had significantly better vision than those who did not.

The idea is that a certain amount of bright ambient light - the kind you see outside - is required for optimal eye growth. But the research is always evolving.

It's not just screens

Much to my surprise, despite an increase in my screen time since my last visit - which may have been a wee bit overdue - my vision had actually improved.

"With short-sightedness, it deteriorates up to a point, stabilises and improves a little bit later in life again," Dr Ferreira tells me.

So maybe the screen isn't the devil I thought it was.

"There's some evidence that more 'near work' [focussing on things up close] can be associated with myopia development and progression," Dr Read says.

"But it's not necessarily just screens, it could be reading up close from a book."

Screens get more of a bad rap than the humble book.

That's partly to do with the blue light they emit, which has been increasingly demonised.

Is blue light damaging?

Evidence, mainly from animal studies, show exposure to high levels of blue light can damage retinal cells at the back of the eye.

So is blue light destroying our eyes?

"The amount of blue light that those devices emit is very, very small - much less than would cause retinal damage," Dr Read says.

"Even with very long-term viewing conditions, that amount of blue light is less than what you get from being outdoors in natural light."

For smartphone addicts, blue light could be more of a sleep disrupter than a retina burner.

Blue light helps the body know when it's daytime, so exposure to it after dark can throw off a person's sleep cycle.

A 2018 report recommended limiting screen use at night, because without enough shut-eye, the liquid in our eyes can evaporate, leading to dry eyes.

Do we need special filters?

Some optometrists offer filters on lenses to help combat the impacts of blue-light exposure. But Dr Read says it's difficult to assess how effective they are.

"There are some claims they may help reduce eye strain symptoms from computer work," he says.

"But in terms of high-quality research evidence, there isn't a lot of that at the moment."

Anecdotally, results are mixed, he says.

"Some people report benefits, other people don't notice much difference."

Look away - at least for a little while

So what can we do to protect our eyes from our screens?

Dr Ferreira says it's about taking a break.

"When we look at the screen, we tend to concentrate a lot more and blink less and the tears break up and form dry spots on the eyes," he says.

"That's when you start getting the tiredness and irritation.

"Look up every half hour at something about six metres away.

"Every hour, you need to get up, preferably go outside and look at the mountains and the clouds."

Of course, he admits this is unrealistic for some, and that even he is shocked by how long he can spend glued to a screen.

The good news is that screens probably aren't rotting our eyeballs and the tired, dry feeling our eyes tend to get when they've been staring too long will go away.

Just remember to log off every now and then, ok?

25. toukokuuta 2019 9:50:00 Categories: ABC Health Techly

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