So we're inside were in fake leading we're not spending as much time outside in the context which are visual system of ball. Amanda Mylene assistant professor of anthropology and archaeology and of medical genetics at the university of Calgary. And all that sitting inside in dim light staring at screens has led to an epidemic of myopia - nearsightedness - among young people. The myopia epidemic is particularly strong in Asia and in urban Asian environments where is increasing to be upwards of ninety percent of teenagers are myopes. Mylene spoke February 20th at a press briefing at the annual meeting of the American Association for the advancement of science in Boston. So to be sure there's a genetic component my father had glasses I have classes but we're increasingly realizing that the environments in which we're spending our time are playing a major role in so accord study were some school age children were given 40 minutes or more time outside. Those children had a 23 to 50 percent less likely chance of developing myopia than students at schools were not given that same amount of outdoor exposure and it looks to be dosage dependent so the longer time you spend outside the less chance you have of developing myopia.