Time Spent Outside In Youth Can Affect Nearsightedness

Photo credit: bigstock.com

Photo credit: bigstock.com

Nearsightedness has been a growing problem for years for millions of people, but for a long time, no one was quite sure why. Until recently, many people considered bad vision something you were simply born with. Research appeared to indicate that the ever-increasing amount of time people spent focusing on objects in close proximity to their eyes was causing nearsightedness. Activities such a smartphone use, computer use, and even reading were deemed contributing factors to vision decline. However, new findings have shown that it may actually be the amount of time you spend indoors during your formative years that determines whether or not you’ll be needing glasses or contact lenses later in life.

 

The relationship between sun exposure and visual acuity

The rates of myopia, or nearsightedness, have skyrocketed all over the world over the last few decades, and no one is quite sure why. In the 1970s, approximately 25 percent of people in the United States were nearsighted; today it is as high as 42 percent. In East Asia, the problem is even more pronounced, with countries such as Japan, South Korea, and Singapore having some of the highest levels of myopia in the world. What’s going on? What has changed over the past few decades?

There is a great deal of evidence that myopia is an inherited trait. If this is the case, why is it that people with nearsightedness were not simply weeded out of the gene pool over time?

The truth is that while genetics is definitely a factor, environment and lifestyle can play a huge role in determining whether or not vision develops properly. It turns out that over the past few years, many people living in developed countries have developed a phobia of the sun. Consider how the average person lives today: waking up in a heated and air conditioned home, driving to and from work (which is also climate controlled), going shopping, etc. … all of these activities take place inside. The only sun exposure such a person might get is in the few seconds they’re walking from their car to their destination. Compare this to our ancestors: Even as recently as a few generations ago, people spent much more time outside.

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Photo credit: bigstock.com

Photo credit: bigstock.com

The Evidence

A study published in a 2008 issue of the Archives of Ophthalmology found that the amount of time spent outdoors during childhood does indeed influence the likelihood of developing myopia in children. In this study, researchers compared the levels of myopia in children ages 6 to 7 years old in Singapore versus children of the same age living in Sydney, Australia. The researchers found a 29 percent higher incidence of nearsightedness in the Singaporean children than the Australian children. When comparing the lifestyles of these two groups, the researchers came upon one glaring difference: The children living in Singapore spent, on average, only 3 hours a week outside, while the children in Sydney averaged 14 hours outside each week.

The effects of sunlight exposure (or lack thereof) during childhood and teenage years can last well into adulthood. In a study published in JAMA Ophthalmology, scientists interviewed over 3,000 people living in different European countries, including Greece, the United Kingdom, Italy, Norway, Spain, France, and Estonia. The study participants were an average of 65 years old, and included 371 people with myopia and 2,797 people without it.

Participants were asked a variety of questions about their medical history, diet, and most pertinently, how much time they spent outside on average, beginning from age 14 up to the present. They also underwent blood tests to see if there was any variation in their vitamin D levels.

The European study seems to confirm what the study on the Australian and Singaporean children found: The adults who had more sunlight exposure over the course of their lives—and in particular their early lives—had lower levels of nearsightedness. Interestingly, the amount of vitamin D in the body did not seem to correlate to myopia levels. Rather, it appears that sunlight helps children’s eyes maintain the proper distance between the retina and the lens. This is what helps keep vision in focus.

These studies show a definite association, but not a complete cause and effect relationship, between sunlight and vision. But they do strongly suggest that living a decidedly more natural lifestyle of getting a healthy amount sunlight each day during our youth can dramatically lower the risk of developing myopia later in life.

 

READ ALSO: How To Keep Your Eyes Healthy In A Digital World Infographic

 

This is just one more argument for why getting more sun is good for us. If you have kids, tell them to put down the video game controller and put them outside for a few hours a day after school. They may complain, but they’ll be thanking you years later when they don’t need contacts.

References:

www.ncbi.nlm.nih.gov

www.aoa.org