THREE KEY FACTS

• Myopia means you can see things clearly that are near, but have trouble seeing objects that are farther away. In some cases, this can lead to serious eye problems later.
• Eyes turn inward while closely viewing a screen, causing a muscle behind the iris of the eye – the ciliary body – to contract, changing the shape of the lens.
• Myopia can’t be reversed or cured, and children can’t “outgrow” it.

As opposed to television, experts say the danger now comes from smartphones, tablets and computers, with almost every kid using a screen of some kind.

The question: Is it true that sitting too close to a television will damage your eyes?

The science: Baby boomers – actually anyone 60 or older – repeatedly heard this warning from their mothers growing up.

Turns out, Mum was on to something. Watching a screen up close for long periods of time will affect eyesight. But the danger now comes from smartphones, tablets and computers.

“Your mother was right, but the screen has changed,” said Marcela Estrada, an assistant professor of ophthalmology at the University of California at Davis. “And today, every kid has a screen.”

Children, especially those ages 7 to 15, have the highest risk for eye problems such as myopia or near-sightedness, but young and older adults may also face eye issues.

Since the introduction of large flat-screen TVs, the little cabinet TVs have become obsolete, and the risks from TV screens are not as great. Large-screen TVs make it harder to see everything on the full screen if you sit too close, so viewers tend to keep their distance, reducing potential harm.

But tablets, smartphones and computers are often less than an arm’s length away, which is too close to our eyes, experts said.

“Everybody in school and at home are now on their phones and tablets, and more time spent doing this ‘near work’ can increase the incidence of myopia,” said Masih Ahmed, an assistant professor of ophthalmology at the Baylor College of Medicine. “This is occurring mainly in kids because that’s when the eye is developing the most.”

Myopia means you can see things clearly that are near, but have trouble seeing objects that are farther away. In some cases, this can lead to serious eye problems later, experts said.

Eyes turn inward while closely viewing a screen, causing a muscle behind the iris of the eye – the ciliary body – to contract, changing the shape of the lens. This results in myopia.

Eyes turn inward while closely viewing a screen, causing a muscle behind the iris of the eye – the ciliary body – to contract, changing the shape of the lens. Photo / 123rf

“The eye lens gets fatter,” Estrada said. “When you consistently focus too close, the eye lens spends more time accommodating and changes its shape to focus the image on your retina. If you do this too much, then you will encourage your eye to grow too fast,” which promotes myopia.

“Your eyes stop growing between ages 18 and 25, so it’s especially important to pay attention to this issue in younger children,” said Daniel Cyr, a paediatric ophthalmologist at Stony Brook Medicine. “The younger they’re found to be myopic, the more likely it is they will become ‘highly’ myopic, which is an extreme form of near-sightedness – they can only see things that are right in front of their faces, within a foot – which puts them at greater risk for degenerative eye conditions such as vision loss, retinal detachment, cataracts and glaucoma.”

There also are genetic conditions such as Stickler syndrome and Marfan syndrome that cause “high myopia,” Estrada said. Also, having one parent with myopia increases the risk, especially if that parent has extreme myopia. And if both parents are myopic, the risk is higher and the “degree of myopia tends to be worse,” she said.

Myopia can’t be reversed or cured, and children can’t “outgrow” it, but it can be corrected with eyeglasses or contact lenses and, for adults, laser surgery, according to the National Eye Institute.

Young adults – those in their early 20s – can also have late myopic progression with excessive near work, Estrada said. And after reaching their 40s, adults can develop presbyopia – when the lens is less able to bend to focus on things. That age group will feel asthenopia or significantly more eyestrain or fatigue, and some will develop diplopia or double vision, from an inability to sustain near focus, she said.

What else you should know

There are a few steps parents can take to reduce the risk of their child developing myopia or it getting worse, experts said.

Limit home screen time for non-school work to one hour or less every day. “This may be tough for a teenager, but the important time is during the younger years when you still have some control over their use of these devices,” Cyr said.

Ask children to hold the screen at least an arm’s length away, Estrada said.

Put the tablet in a heavy case, “which makes it harder for a child to hold for long periods of time,” or set it on a stand on a desk, Estrada recommended.

Have them spend time outside. “Two hours a day outside is a good preventive,” against myopia, Estrada said. Growing evidence suggests that increasing a child’s time outdoors helps prevent the onset of myopia, although some research finds it unlikely to slow its progression in eyes that already are myopic. Experts aren’t sure why sunshine helps, “but there is something about being in the daylight,” Ahmed said. Perhaps “you are not in an enclosed visual space, and objects are at” more of a distance. Or, Estrada said, “it could just be that being outdoors relaxes the work of the eyes.”

Get at least one professional eye exam for every child, including babies, before they reach kindergarten age, Cyr said. “With infants, we have tools that take a picture of a child’s eye that measures refractive errors, meaning whether child’s eye needs correction,” he said. “Paediatricians have tools to screen them. If they fail, they should go to a paediatric ophthalmologist.”

The bottom line: viewing a screen up close can affect eyesight, especially in young children. Some older adults feel eye fatigue or develop double vision.

“The sweet spot where high near tasking probably won’t harm your eyes, other than dry eye symptoms, is between the ages of 25 to 45. Outside of that, don’t sit too close to the TV or screen,” Estrada said.

HEALTH CHANGES

• Consult a GP or other qualified healthcare provider before making any health changes suggested in this article. Always seek the advice of your GP or other qualified health provider with any questions you may have.
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