Sydney University researchers have suggested that children who spend more time outdoors are less likely to develop short-sightedness.
This finding may provide the basis of a public health initiative to prevent the development of myopia in young children and adolescents.
The NHMRC-funded Sydney Myopia Study was a large school-based study of over 4,000 Year 1 and 7 students from 55 schools located across the Sydney metropolitan area.
Each child had a comprehensive eye examination at an ophthalmic clinic. Accurate measurement of refractive errors (myopia, hyperopia and astigmatism) was conducted using an international standard regime of eye drops, similar to that adopted in recent WHO sponsored studies.
Dr Kathryn Rose of the Faculty of Health Sciences, University of Sydney, said: "Our results show that the protective effect of time spent outdoors persists even if a child is doing a lot of near work such as reading and studying.
"Television watching and using computers appears to have little effect on the development of refractive errors. Our recently published comparison of age-matched Chinese children from Sydney and Singapore showed the same trend.
"The results of this study are consistent with an American study which found that outdoor sport was protective, however our study shows that the crucial feature is being outdoors irrespective of the activity you are doing."
One of the chief investigators, Professor Paul Mitchell of the Centre for Vision Research and Westmead Millennium Institute, said: "Nearly 80% of all children invited to participate in the study enrolled to have their eyes tested, which is important to ensure that our findings apply to all children."
Prevention of myopia is important for future eye health, avoiding increased rates of cataract and glaucoma in adulthood and, in cases of high myopia, possible irreversible visual impairment. Promoting outdoor activity to parents and families, and including more outdoor pursuits in school curricula, could be an important public health measure to avoid the development of myopia.
This public health message would be particularly relevant in those countries where the rates of myopia in children are very high, such as in Singapore and Taiwan. This strategy would also be compatible with the public health message on the importance of physical activity in relation to childhood obesity.