Warning: Looking at Your Phones in the Dark Can Cause ‘Smartphone Blindness’

Looking at your smartphone in the dark may cause temporary blindness, doctors said.

Doctors discovered this condition when two women in the UK reported mysterious vision problems that happened only during the night or early in the morning.

According to medical experts, this vision problem occurs when people look at the bright screens of their smartphones in a dark room.

In a report published in the New England Journal of Medicine, doctors detailed the cases of two women aged 22 and 40, who experienced "transient smartphone blindness" for months.

The 22-year-old woman said she had trouble seeing from her right eye at night lying in bed, and that this happened multiple times a week for one year. She could only see an object's outline with her right eye. Her left eye vision was normal, and both eyes were able to see normally the following day, Live Science reported.

In the case of the 40-year-old woman, she reported that she could not see from one eye after waking early in the morning, before sunrise. This occurred on and off for six months and lasted for about 15 minutes.

In both cases, doctors found that the vision problems happened only after the women reportedly viewed their smartphones for some time while lying in bed.

Dr. Gordon Plant of Moorfield's Eye Hospital in London explained that both women look at their smartphones with only one eye while lying on their side in bed in the dark. The other eye was usually covered with a pillow.

"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," he said in a report published in NZHerald.com.

The women were asked to try looking at their smartphones with both eyes, and then with each eye individually. The women reported that they did not experience the blindness when looking at their phones with both eyes, and when looking at the phone using one eye, the blindness happened in the eye that had been viewing the smartphone.

Temporary blindness is ultimately harmless and easily avoidable if people will look at their smartphones using both eyes, Plant said.

According to the report, cases of "smartphone blindness" are likely to increase as smartphones are now being used around the clock and smartphone screens are increasing in brightness.