Playing Outdoors Helps Children see further

A new analysis of recent eye health studies shows that more time spent outdoors is related to reduced rates of nearsightedness, also known as myopia, in children and adolescents.

Myopia is much more common today in the United States and many other countries than it was in the 1970s. In parts of Asia, more than 80 percent of the population is nearsighted.

The analysis suggests that more exposure to natural light and/or time spent looking at distant objects may be key factors.

The analysis was led by Dr. Justin Sherwin of the University of Cambridge.

The data included in the analysis was drawn from eight carefully selected studies on outdoor time and myopia in children and adolescents, representing 10,400 participants in total.

Dr. Sherwin’s team concluded that for each additional hour spent outdoors per week, the chance of myopia dropped by approximately two percent.

Nearsighted children spent on average 3.7 fewer hours per week outdoors than those who either had normal vision or were farsighted.

Though the reasons aren’t yet clear, the protective effect appears to result from simply being outdoors rather than performing a specific activity.

Two of the eight studies examined whether children who spent more time outdoors were also those who spent less time performing near work, such as playing computer games or studying, but no such relationship was found in either study.

The amount of time spent on near work is of interest to researchers as another potential cause for the recent uptick in nearsightedness.

“Increasing children’s outdoor time could be a simple and cost-effective measure with important benefits for their vision and general health” said Dr. Khawaja.

“If we want to make clear recommendations, however, we’ll need more precise data. Future, prospective studies will help us understand which factors, such as increased use of distance vision, reduced use of near vision, natural ultra violet light exposure or physical activity, are most important.”

Myopic Americans: Nearsightedness Rising in U.S.

Myopia appears to have become 66 percent more common in the U.S. between the early 1970s and early 2000s, according to a recent study in the Archives of Ophthalmology.

Vision tests in the 1970s found that about 25 percent of Americans were nearsighted at the time, while similar examinations three decades later found a 42 percent incidence of myopia.

The reason for the uptick in nearsightedness isn't well understood, but some research pegs "excessive amounts of near work, the kind of tasks that require peering at written words or small objects," as a key culprit, according to ScienceNews. But genetic factors are another potential cause. "It might be that somehow the population has changed and that there are more people floating around that have more genetic risk," says one of the study's authors.

Killer Asteroid Hunter suffering from Short-Sightedness

The first of the asteroid-hunting Pan-STARRS telescopes will be taken apart today in an effort to solve problems with image quality.

The 1.8-metre PS1 telescope is the first of a suite of instruments – the Panoramic Survey Telescope and Rapid Response System – designed to find asteroids and comets with orbits that could bring them close to Earth.

Sited atop a volcano on the Hawaiian island of Maui, PS1 is the prototype for a planned four telescopes that will image the whole sky visible from Hawaii three times each month.

To scan so much sky, PS1 boasts a 1.4-billion-pixel digital camera and specially designed software to process the terabytes of data collected by the telescope each night.

But since the camera was installed in 2007, the telescope team has been struggling to get PS1's image quality to its targeted level. "There have been problems that we just didn't anticipate," says Pan-STARRS principal investigator Nick Kaiser of the University of Hawaii at Manoa.

Big bananas

PS1's first problem was a misalignment of the optics. "When we switched the telescope on two years ago we had terrible-looking images. We could get sort-of round stars in the middle of the field, but they were big and fuzzy. But the stars at ends of the field looked like telephone handles or big bananas," Kaiser told New Scientist.

That problem was quickly fixed, but the images PS1 is taking are still 40 to 50 per cent fuzzier than they are supposed to be. "We're spending half our time doing mediocre science and half our time trying to improve it so we can do great science," says PS1's director, Ken Chambers, a colleague of Kaiser at Manoa.

The main culprit now seems to be a set of joints connected to the 18 rods that hold up the telescope's secondary mirror. These joints help connect the mirror to motors that adjust the mirror to counteract distortions of the telescope, which expands and contracts due to temperature changes and sags slightly as it scans across the sky.

The minute adjustments of the mirror are not occurring as they should be owing to a flaw in the original design, says Kaiser. So a crew will remove the secondary mirror to replace the joints and make other improvements to the support structure. The telescope is expected to be offline for several weeks, but if all goes well the procedure should go a long way toward improving the telescope's image quality.