Vision loss in one eye can be a sign that a person is having a small stroke, which is why one of the women was put on blood thinners and the other got a brain scan. It can also signal a compressed optic nerve.
But after further investigation, researchers writing Wednesday in The New England Journal of Medicine think the problem is much simpler. They're calling the affliction "transient smartphone 'blindness.' "
"They were looking at their smartphones and they just happened to have one eye covered because they were lying in bed," says Omar Mahroo, an ophthalmologist at Moorfields Eye Hospital in London and an author on the letter.
A 22-year-old woman in England thought she was going blind in one eye. She could always see fine out of her left eye. But on some nights, the right eye failed her. All she could see out of it were vague shapes in the room.
At first, it happened about two or three times a week. Then it started happening every night.
When she went to the doctor, her vision appeared normal. So did brain scans. But it was a disturbing trend.
Around the same time, another woman noticed the same thing. On some mornings, she'd lose vision in just one eye for up to 20 minutes. It was bothersome enough to land her in the emergency room.
- Read more: NPR.org