Children’s Nearsightedness: Linked to Nature Deficit?
BY Jennifer Wise
We don’t mourn the loss of what we don’t see.
In fourth grade I had no idea that the equations I copied from the board were incorrect, I only knew that for the first time my math papers were handed back with poor marks and my grades kept getting worse. Although I wrote neatly and rechecked my work the teacher scrawled “careless mistakes” on my papers. I’d decided I was a mathematical dunce by the time my parents realized I needed glasses.
It was a revelation the first time I put on those glasses. I could see individual leaves on trees! I could see the faces of people passing by! I thought what I’d seen before, blurry images that resolved close up, was what everyone saw.
Myopia has risen to epidemic levels. In the United States, young adults are much more likely to be nearsighted than people in their grandparent’s generation. In 1996, sixty percent of 23 to 34 year olds were nearsighted compared to twenty percent of those over 65. Some Asian countries are seeing an even more alarming increase, up to 80 percent of young adults.
All sorts of possible factors have been blamed for causing this: reading too long, sitting too close to the television, even going without sunglasses. Some of it’s true. For example, there are consequences for too much screen time, something the American Optometric Association (AOA) terms “Computer Vision Syndrome.” Common symptoms include headaches, blurred vision, dry eyes, and eyestrain. On aoa.org, they explain: “Viewing a computer screen often makes the eyes work harder. As a result, the unique characteristics and high visual demands of computer viewing make many individuals susceptible to the development of vision-related symptoms…. The level of discomfort appears to increase with the amount of computer use.”
But research points to a another possible cause that has resounding significance for the way we raise our children.
The startling cause uncovered by researchers in three separate studies in the U.S., Australia, and Singapore? It has to do with the amount of time a child spends outdoors.
Yes, genetics still play a part. Children born to nearsighted parents are more likely to need corrective lenses.
But researchers noticed an intriguing outlier. Children who devoted more hours per week to sports or outdoor play were less likely to develop myopia. Perhaps, it was speculated, they spent less time on close activities like reading. But further studies didn’t make that connection.
Perhaps, it was speculated, that sports and other activities made them more physically fit, somehow benefiting their eyes. But indoor sports were found to have no correlation with better eyesight, only those played outdoors. In fact, even completely inactive time outdoors was helpful in reducing the incidence of myopia.
Look at these numbers. A study of six to seven year olds (only of Chinese ethnicity to simplify comparisons) living in Singapore and Australia found marked differences based on outdoor exposure. Children in Singapore spent an average of three weekly hours outdoors, thirty percent developed myopia. Australian youngsters spent 14 hours outside each week, only three percent developed myopia.
No one is sure exactly what factors lead to better eyesight when children spend time outside. It may be related to the greater intensity of light or the natural spectrum of light. Perhaps it has something to do with nutrient absorption related to light, as in vitamin D metabolism.
Or it may relate to peripheral vision. Without the limitations of walls and windows our vision can range across open spaces. This corresponds to findings that urban children, whose vision is constrained by crowds and buildings, suffer a greater incidence of myopia than rural children.
Whatever the cause, today’s children spend more time indoors than their parent’s generation. Actually, about 90 percent of their young lives are spent shut away from the natural light and wider view of the outdoor world.
They can’t miss what they don’t see.
Eye Wish by Nell Boyce, New Scientist
Generation Specs: Stopping the Short-Sight Epidemic by Nora Schultz, New Scientist
Vitamin D Complex in Progressive Myopia by A. A. Knapp, The Journal of Nervous and Mental Disease
Myopia and the Urban Environment: Findings in a Sample of 12-Year-Old Australian School Children by Jenny M. Ip, Investigative Ophthalmology and Visual Science
Research & Resources Children & Nature Network, childrenandnature.org