Using your smartphone in bed in the dark can cause a temporary loss of vision, eye experts are warning.
An article in The New England Journal of Medicine examines the case of 2 patients who attended a clinic at Moorfields Eye Hospital in London after experiencing recurring episodes of temporary blindness.
The first case involved a 22-year-old woman who had experienced impaired vision in her right eye at night for several months. The second case involved a 40-year-old woman who experienced 6 months of visual impairment in one eye for up to 15 minutes when she woke.
Smartphones in Bed
When both patients were seen by specialists in the hospital's neuro ophthalmic clinic, it was found that both women's symptoms developed minutes after they had viewed their smartphone screen while lying in bed in darkness.
Further investigation showed that both patients typically looked at their phones with only one eye while resting on their side and that their other eye was covered by a pillow.
The experts explain that while one eye got adapted to the dark, the other became used to the bright light from the phone's screen.
When the women used both eyes again, the one that had been staring at the screen was unable to cope with the darkness, leading to the sensation of a loss of vision.
Two of the authors replicated the situation themselves, looking at their smartphones in the dark with only one eye and found it took their eyes several minutes to recover.
The experts say that as smartphones are increasingly being manufactured with brighter screens and are used day and night, this phenomenon is likely to become more common.
Transient smartphone 'blindness', Dr G Plant et al, The New England Journal of Medicine
Moorfields Eye Hospital
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