By Sushant Shrestha SushantaIf you want to avoid your child having vision issues later in life then let them go into the outdoors. It is a message from researchers looking into an expected increase in the worldwide rate of short-sightedness.The World Health Organization (WHO) has said short-sightedness, or myopia, already affected about 30 percent of the world's population. That figure is expected to rise to 50 percent by 2050 and this is because all the time children are spending indoors. Myopia develops when the eye becomes elongated. Light entering the eye focuses in front of the retina, and objects further away become harder to see."They are at much higher risk of having early onset glaucoma and cataract if they are a moderate myopic," Professor Kathryn Rose, said head of orthotics at the University of Technology Sydney.Professor Rose worked with the Sydney Myopia Study, which assessed the vision of 4,000 school children. At first it was thought that myopia must be due to children spending more time on computers, smart phones and iPads. Now many researchers agree that it is not the real cause but a related issue only. Increased myopia is most likely caused by children spending less time outside."There have now been two trials, one in Taiwan and one in China that have actually shown that they can reduce the incidence of myopia in those populations by increasing time outdoors for children."It is also proved that 10-15 hours a week outdoor is enough to prevent the development of myopia," Professor Rose said. It is found that the country with sufficient greenery have least chance to get suffer from myopia in upcoming days.