Why do so many of us need glasses? More and more kids need glasses for long distance vision everyday. Is there a major genetic flaw influencing our vision at a rapid rate? Turns out our kids are indoors too much during a critical developmental stage in their vision.
Around 3rd grade, the eye grows just a little bit. Scientists are discovering that if the eye does not have adequate adrenaline flooding the eye during this growth period, it does not keep the correct shape for proper vision. Where does the adrenaline come from? It is produced by the eye when more than 10,000 lux worth of light inters the eye. Scientists are finding that 3 hours of outdoor light is sufficient to help prevent myopia in children.
Now you have another reason to send your kids outdoors to play!
Article from Treehugger:
In the U.S. and Europe, myopia for kids and young adults has doubled; in China it’s up 80 percent. Scientists think they’ve found out why, and it’s probably not what you think.
Sixty years ago, 10 to 20 percent of the Chinese population was nearsighted, now up to 90 percent of teenagers and young adults have trouble seeing distance. In other parts of the world the story is similar: Half of the young adults in the United States and Europe now have myopia, double the number of half a century ago. And some are predicting that by 2020, one-third of the world’s population could be diagnosed with the condition.
While glasses, contact lenses and surgery can help to correct nearsightedness, they don’t actually cure the defect – a slightly elongated eyeball, which means that the lens focuses light from far objects slightly in front of the retina, rather than directly on it, reports Elie Dolgin in the science journal Nature. And when it’s severe, there exists the risk of retinal detachment, cataracts, glaucoma and blindness.
The condition usually develops in school-age kids because this is when the eyes are growing; around 20 percent of young adults in East Asia now have severe myopia, and half of them are expected to develop irreversible vision loss.
What in the world is going on?
For years the thinking was that myopia was largely genetic, but research began to show that it wasn’t purely a matter of genes. And indeed, the current increase in myopia reflects a similar increase in children reading and studying more – in fact, is there a caricature of a “bookworm” that doesn’t include glasses? Add to this a newfound addiction to computer and smartphone screens and the answer seems obvious, right? Our kids are so focused on these close-at-hand objects, of course they’re losing their ability to see distance.
“On a biological level, it seemed plausible that sustained close work could alter growth of the eyeball as it tries to accommodate the incoming light and focus close-up images squarely on the retina,” notes Dolgin.
But surprisingly, it’s not the reading and computers and smartphones that are to blame. Now researchers believe that it’s the very act of spending too much time inside that is causing the problem. After a great deal of research and eliminating other factors, scientists now think that it boils down to exposure to light. Regardless of what kids are doing – whether sports, or playing, and even those who continue to do “close work” (like reading) outside – what seems to be key is the eye’s exposure to bright light.
Based on epidemiological studies, Ian Morgan, a myopia researcher at the Australian National University in Canberra, recommends that children spend three hours per day under light levels of at least 10,000 lux for protection against the condition. Ten thousand lux would be about the amount of light one would get from beneath a shady tree on a bright summer day (and wearing sunglasses). For comparison, a well-lit schoolroom or office is generally under 500 lux.
In Australia, where three hours of outdoor time is normal, only 30 percent of 17-year olds are nearsighted. In other parts of the world where myopia rates are higher – like the U.S. and Europe – many children don’t see more than an hour or two of outdoor time.