The longer children and adolescents spend outdoors the lower their risk is of developing myopia (nearsightedness), researchers from the University of Cambridge, England reported at the 115th Annual Meeting of the American Academy of Ophthalmology, Orlando, Florida. The study was led by Dr. Justin Sherwin and presented by Dr. Anthony Khawaja. Khawaja explained that nearsightedness is much more prevalent in America today than it was thirty or forty years ago. In some regions of Asia over four-firths of the population has myopia.

This latest analysis appears to show that the amount of time children and teenagers are exposed to natural light, as well as how long they spend looking at far-away objects impact on their quality of vision.

Dr. Justin Sherwin and team carried out a meta-analysis of eight studies that focused on myopia in children and adolescents and how long they spend outdoors. The studies involved a total of 10,400 individuals.

In myopia (nearsightedness) the image focuses in front of the retina

The team worked out that there was a 2% drop in myopia risk for every additional hour spent outdoors each week. They reported that the average nearsighted child spends 3.7 fewer hours outdoors each week compared to children with no vision problem or those who are farsighted. Farsightedness, also known as hyperopia, is the ability to see distant objects more clearly than close objects.

In hyperopia (farsightedness) the image focuses behind the retina

The scientists believe that the protective effect does not come from any particular activity, but rather due to the simple act of being outdoors. Two of the studies they analyzed attempted to determine whether those who spent more time outside also spent less time on near work, such as studying or playing games with a monitor in front of them – there was no evidence of such a link in either study. The researchers are currently looking into whether time spent on near work might eventually have an impact on a child’s vision.

Dr. Khawaja said:

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

The investigators also wondered whether nearsighted children might benefit from extra hours outdoors – would this stop their myopia from becoming more severe. Dr. Khawaja mentioned a Chinese study of 80 children aged 7 to 11, all of them with myopia. They were randomly selected into two groups of 40:

  • The intervention group – they were made to spend no more than 30 hours each week on near work and at least 14 hours outdoors
  • The control group – they had no intervention. They were not told to change or monitor their outdoor time or time spent doing near work.

They found that after 24 months those in the intervention group had less nearsightedness than those in the control group. This Chinese study was not one of the 8 Khawaja and team analyzed.

Written by Christian Nordqvist