Most people are aware of the social problems that come from staring at a smartphone for hours, but could the physical damage be even worse? That's the question being asked in China, where a woman has gone partially blind after spending an entire day playing a popular mobile game.

21-year-old Wu Xiaojing had been enjoying multiplayer title Honor of Kings, also known as King of Glory, for a number of hours without taking a break when she lost the vision in her right eye. After arriving at hospital, she was diagnosed with Retinal Artery Occlusion (RAO), a condition caused by an obstruction of the blood flow to the retina from the retinal artery.

Wu is one of the 163 million+ people in China who regularly play Honor of Kings. "If I don't work, I usually get up around 6am, have breakfast, then play until 4pm," she said, "I would eat something, take a nap, wake up and continue playing until 1 or 2am."

The finance worker spent the whole of October 1, a Chinese holiday, playing the game. She lost sight in her eye and went to hospital sometime after dinner.

Whether the gaming session was the cause of her RAO is still being debated. A specialist from the hospital that diagnosed the condition said her excessive gaming likely brought it on, but others believe it is the sign of an underlying condition, such as cardiovascular disease. Dr. David Allamby, an eye surgeon and the medical director of London's Focus Clinic, told the Daily Mail there's a slight possibility that staring at the phone for long periods gave Wu a migraine, which can in rare cases bring on RAO.

What isn't in doubt is that staring at a smartphone screen in bed at night can cause temporarily blindness. The issue arises when people are lying on their side and use just one eye to look at the screen. "You have one eye adapted to the light because it's looking at the phone and the other eye is adapted to the dark," explained Dr. Gordon Plant of Moorfield's Eye Hospital in London. When they stop looking at the phone, they're blind in one eye as "it's taking many minutes to catch up to the other eye that's adapted to the dark."

Back in July, Tencent announced it would be limiting the amount of time younger players could spend on Glory of Kings, which is dubbed 'internet heroin' by Chinese media. It certainly lives up to its addictive nature, judging from the fact Wu was still holding her smartphone when pictured lying in the hospital bed.