A study has found an association between children, aged three to nine, who spend additional time spent outdoors and a reduced incidence of myopia between ages 10 and 15. Additionally, it identified a trend for the association to increase toward the older end of the three to nine years range.
Myopia is a global problem with increasing prevalence reported across the world. This eye condition poses a significant financial and social burden for individuals who are faced with on-going cost of optical correction, lowered self-esteem, and reduced participation in recreational activities.
Time spent outdoors during childhood has been negatively associated with the incidence of myopia and consequently, additional time outdoors is being promoted as a public health intervention.
Researchers studied 2,833 children aged between two and 15 years who were participating in the Avon Longitudinal Study of Parents and Children (ALSPAC). Their aim was to investigate whether there were specific ages when the amount of time outdoors might directly impact the incident of myopia. Parents of the participating children were asked to report on the amount of time spent outdoors and the time spent reading at age intervals of two, three, four, five, seven and nine.
Additionally, the researchers measured the children’s mean spherical equivalent refraction with noncycloplegic autorefraction five times between the age of seven and 15 years. Other risk factors, including sex, the myopia status of parents and average time spent reading by the children, were also analysed.
The researchers reported that from three years of age onward, greater time outdoors was associated with a reduced risk of incident myopia. They stated, that the hazard ratio for myopia changed progressively from 0.90 (95 per cent CI 0.83-0.98, P = 0.012) at age three years, to 0.86 (95 per cent CI 0.78-0.93, P = 0.001) at age nine years, for each additional SD of time spent outdoors per day. Additionally, they noted that these associations were independent of two major risk factors for myopia: time reading and number of myopic parents.
The study was published in Investigative Ophthalmology & Visual Science 2017;58(2):1158-1166. doi: 10.1167/iovs.16-20894.