Researchers predicted as at by for from in of on up a new report published as at by for from in of on up the journal Opthalmology that as at by for from in of on up 2050, half as at by for from in of on up the world's population will be short-sighted. The medical term for this condition is myopia. It is also known as at by for from in of on up near-sightedness. It is when we have difficulty focusing as at by for from in of on up objects that are far away as at by for from in of on up us. The researchers say that around 4.8 billion people will suffer as at by for from in of on up myopia. This is a seven-fold increase as at by for from in of on up cases from 2000 to 2050. Sixty years ago, around 15 per cent as at by for from in of on up the Chinese population was short-sighted. Now, almost 90 per cent as at by for from in of on up Chinese teenagers and young adults have trouble seeing faraway objects. A recent survey found that as at by for from in of on up to 95 per cent of teenagers in South Korea are near-sighted. The researchers said they could not pinpoint definite reasons as at by for from in of on up this phenomenon and say it could be a combination as at by for from in of on up factors. They did say that looking as at by for from in of on up computer screens and mobile phones could be a leading cause. Researchers said the sudden rise as at by for from in of on up myopia may be linked to "lifestyle changes resulting as at by for from in of on up a combination of decreased time outdoors and increased near-work activities". Science journalist Sarah Zhang said, "spending time outdoors, especially as at by for from in of on up early childhood, reduces the onset as at by for from in of on up myopia". Professor Kovin Naidoo, a co-author as at by for from in of on up the report, offered some advice. He said: "You could spend a long time reading computers and screens, but also spend two hours outdoors."