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Science

Um, apparently your smartphone can make you blind

We’ve all been warned about the dangers of smartphones: tech neck, sleep disorders, social issues etc. etc. But now there’s a fun new issue to worry about – transient smartphone blindness.

The New England Journal of Medicine presented two cases of smartphone users, both women, one in her twenties, the other in her forties, who had recurring issues with temporary blindness in one eye for months.

After running all the tests they could think of, doctors had no medical answers for the vision impairment, until they realised that symptoms only occurred after staring at a smartphone screen in bed in the dark.

“I simply asked them, ‘What exactly were you doing when this happened?’” wrote Dr Gordon Plant, of Moorfield’s Eye Hospital in London.

Both women generally used their phones with only one eye – the other was in the pillow – while lying on their sides in bed. The blindness only ever occurred in the eye they were using to look at the phone.

“So you have one eye adapted to the light because it’s looking at the phone and the other eye is adapted to the dark,” Dr Plant said.

It’s essentially the same as when you go from a super bright, sunny afternoon to a dark room and you can’t see anything for a few seconds.

When they opened both eyes, they were unable to see with the eye they’d been using to see the screen. The NEJM blames it on “differential bleaching of photopigment”, meaning the eye they’d been using had adapted to the light, while the other eye had adapted to the dark. So when both eyes were opened in the dark, the eye that had adapted to the light seemed to be blind, and it took several minutes for the eye to adjust.

Dr Plant considers transient smartphone blindness harmless in the long run, and – while there are a bunch of reasons not to use your phone in bed – if you must be on Twitter at 2am, he suggests you simply use both eyes when looking at your screens.

About the author

Hannah loves to travel but can’t read a map, so she has plenty of good stories to tell.

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