Being outdoors is good for your kids eyesight

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As a kid, my parents used to tell us that watching too much TV was bad for our eyesight. Given my three kids spend way more time in front of a screen that I did as a child, it got me thinking about whether this has any impact on their eyesight.

In the US, nearly 33% of adults use screen devices for over 9 hours a day. Nearly 25% of kids aged 2-18 use digital devices for more than 3 hours a day. Dr. Christopher Starr, an associate professor of ophthalmology at Weill Cornell Medical College in New York explains that staring at a screen for long periods of time does two things to our eyes:

  1. It causes eye fatigue. When looking at a screen your eye muscles have to focus on a near range object. Over a long period of time, this can cause eye muscle fatigue, just like holding a weight in the gym for a long time will cause muscle fatigue
  2. It causes eye dryness. When looking at a screen we tend to blink up to 50% less than normal. When you are not blinking enough, your tears evaporate more quickly. This can lead to dry spots on the cornea, causing redness, burning and blurred vision

While this does not cause any long term damage to the eye, Dr. Starr recommends we follow the 20-20-20 rule to prevent digital eye strain. Every 20 minutes, focus on an object 20 feet away (approx 6 metres), for at least 20 seconds. This gives your eye muscles an opportunity to relax. Alternatively, have a bottle of lubricating eye drops at hand and use them when you feel your eyes getting dry or irritated.

Dr. Starr goes on to explain that there has been a dramatic increase in the rate of near-sightedness (myopia) in the world, which means you can see ok up close, but need glasses or contact lenses to see far away. The presence of near-sightedness in people aged 12-54 has gone up 66% in the last 30 years. No one knows for sure why this is happening; it could be because of the extensive time we spend on screens, but more recent studies suggest it might be because we spend much more time indoors. There is evidence that you need natural light for your eyes to mature correctly.

Exposure to the sun’s rays is believed to stimulate production of the chemical dopamine, which stops the eyeball distorting the focus of light entering the eye. ‘It’s pretty clear that it is bright light stimulating dopamine release which prevents myopia’, Professor Ian Morgan, of the Australian National University said of the findings published in The Lancet medical journal. Yet the average primary school pupil in Singapore, where up to 90% of young adults are myopic, spends only about 30 minutes outdoors each day – compared with three hours for children in Australia where the myopia prevalence among children of European origin is about 10%. The figure in Britain is about 30% to 40% (maybe because the weather is worse so kids spend more time indoors), and in Africa ”virtually none”, Professor Morgan said.

The Brien Holden Vision Institute at UNSW estimates that myopia levels have risen in the past 15 years from 20% of Australian 17-year-olds to about 30% per cent. ‘Kids who become myopic combine intensive study with not a lot of time outdoors’, said Professor Morgan, who co-authored the landmark Sydney Myopia Study that established the link between exposure to sunshine and short-sightedness in Australian children.

In a bid to arrest the increase in myopia, UTS Orthoptics Professor Kathryn Rose is planning a two-year trial in 42 Sydney primary schools that act as feeders for high academic achieving secondary schools. Half of the 2,000 students recruited would spend an extra hour a day at school outdoors and another extra hour a day outside at home. ‘At academically selective and high-achieving schools, there are substantially higher rates of short-sightedness than in ordinary schools’, said Professor Rose, chief investigator of the Sydney Myopia study.

Myopia is particularly prevalent in Australian students from Asian migrant backgrounds, which culturally place a high value on education. 60% of 17-year-old students of East Asian background are short-sighted, compared with 18% of children of European ancestry, a follow-up study found.

‘We do have a problem group of children in Australia, they’re from Chinese and East Asian origin, who bring their intensive study habits with them’, Professor Morgan said. ‘The big target area is ethnic communities in which education has culturally been seen as the top priority of childhood’. Professor Rose said the problem was now spilling over into children of European background, as some learn from the study habits of migrant children to compete. ‘The rate of myopia is going up in European students’, Professor Rose said. ‘When people become quite competitive around education they adopt some of the [study] behaviours’.

Between 2005 and 2011, the proportion of Caucasian 12-year-olds with myopia increased from 4% to 9%, while the proportion of 12-year-olds of Asian ethnicity with myopia rose from 39% to 53%. However, Australia’s myopia problem pales in comparison to countries like Taiwan, South Korea, Hong Kong, Singapore and China, where up to 90% of students are short-sighted.

While experts agree that screen devices could be exacerbating eyesight problems by giving kids another reason to stay indoors, they say it is the lack of outdoor time rather than the screens themselves that is ruining children’s eyes.

Overseas studies have shown spending an extra 10 to 14 hours a week can reduce the number of new cases of myopia by 25% to 50%. ‘If you could get within the school system [students spending] two to three hours a day outside, you could bring the situation substantially under control’, Professor Morgan said.

So, given the evidence so far, I’m going to try and get my kids to spend more time outdoors, even if that means using their tablets while sitting outside. Every little bit helps!

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Sources

What too much screen time does to your eyes – http://www.cbsnews.com/news/screen-time-digital-eye-strain/
Lack of sun harms children’s eyesight – http://www.smh.com.au/world/science/lack-of-sun-harms-childrens-eyesight-20120504-1y4bw.html
How hothousing kids is ruining their eyesight – http://www.smh.com.au/national/how-hothousing-kids-is-ruining-their-eyesight-20150821-gj4i32.html

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