Persons who read from their smart phones in the dark while lying on their side in bed risk temporary blindness in one eye, British doctors have said.

This was after they detailed the experience of two women, ages 22 and 40, for months in a new report published in the June 23 issue of the New England Journal of Medicine.

The women had complained of recurring instances of "transient smartphone blindness", where they suddenly lose vision in the eye for up to 15 minutes after they were done reading from the smart phone and got up to do other things.

The women subsequently went through different medical examinations, including MRI scans and heart tests. However, the doctors could not find anything wrong with the women until they approached an eye specialist’s office, the report said.

“Both patients were asked to experiment and record their symptoms. They reported that the symptoms were always in the eye contra lateral to the side on which the patient was lying” the report added.

READ ALSO: Why eating cake at work is dangerous to your health

An ophthalmologist with Moorfields Eye Hospital in London, Dr. Gordon Plant explained that both women typically looked at their smart phones with only one eye while resting on their side in bed in the dark while their other eye was covered by the pillow, reports.

“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.“When eventually they put their phone down, it is difficult to see with the eye they were reading the phone with. He added that the eye would need some time to catch up with the other eye that is already adapted to the dark.“That’s because it’s taking many minutes to catch up to the other eye that’s adapted to the dark.”